Crop genomic related with heavy metal toxicity
菜豆多聚泛肽基因在重金属胁迫下的表达_英文_
菜豆多聚泛肽基因在重金属胁迫下的表达_英文_ () 植物学报 1999 , 41 10:1052,1057Acta B ota nica Si nicaΞ菜豆多聚泛肽基因在重金属胁迫下的表达柴团耀张玉秀( )中国科学技术大学研究生院生物部北京 100039( ) 摘要差别筛选 HgCl胁迫的菜豆 Phaseolus vulgaris L . 幼苗叶片 cDNA 库 , 分离出两个重金属胁迫相应基因 2 ( ) PvS R5 和 PvS R51 Phaseolus vulgaris stress- related gene片段。
cDNA 和氨基酸序列分析表明 PvS R5 和 PvS R51 分别编码一种多聚泛肽。
Northern blot 分析表明多聚泛肽是组成性表达蛋白 ,主要在根中表达 ,叶片和茎中表达较少 ; Hg 、Cd 、Cu 和 Zn 等重金属、高温和水杨酸能强烈地刺激其在叶片中的表达 ,而受伤几乎没有影响。
推测多聚泛肽在抵抗重金属胁迫和提高植物的抗逆性方面有重要作用。
关键词重金属 ,多聚泛肽 ,菜豆Expression Analysis of Polyubiquitin Genes from BeanΞ in Response to Heavy MetalsCHAI Tuan- Yao ZHANG Yu- Xiu( )Department of Biology , Graduate School of University of Science and Technology of China , The Chinese Academy of Sciences , Beijing 100039( Abstract Using differential screening of a leaf cDNA library prepared from a bean cultivar Phaseolus vul2) garis L . cv. Saxaexposed to HgCl, the authors have isolated and characterized two heavy metal- regulated 2( ) cDNA fragments , designated as PvS R5 and PvS R51 Phaseolus vulgaris stress- related gene. The sequencesof the cDNA inserts and homological analysis showed that both PvS R5 and PvS R51 encode a polyubiquitin re2spectively. The polyubiquitin genes were constitutively expressed in roots but weakly expressed in stems andleaves. Northern blot analysis revealed a low level of transcripts of polyubiquitin in unstressed bean leaves , butthe gene expression was strongly stimulated by heavy metals , elevated temperature and salicylic acid , whereaswounding had almost no effect . These suggested that polyubiquitin might play important roles in resistance toheavy metals and various environmental stresses.Key words Heavy metals ,Polyubiquitin , Phaseolus vulgarisUbiquitin is a 76 amino acid protein highly con2 mal protein , the ubiquitin- dependent pathway controls the served in all eukaryotes. The ubiquitins are encoded by levels of many key cell regulators , i . e . phytochrome andcyclin. So it plays major roles in various biological pro2 two different gene families , polyubiquitin genes and ubiq2 1 ,2 ) ( uitinextension protein genes UbEP . Polyubiquitin cesses, including DNArepair , transcription , signaltransduction , the cell cycle control , apoptosis and stress genes contain several direct repeats of the ubiquitin codingunit . UbEP genes contain a single ubiquitin coding unit responses. The expression of polyubiquitin genes can be 3 ,4 fused in frame to the coding region for a small protein as2 enhanced by HgClin maize and tobacco , we report 2sociated with ribosomes. Ubiquitin monomer in the cyto2 here the identification and characterization of polyubiqui2 plasm can be covalently attached to other proteins via a tin cDNA from bean and gene expression in response toheavy metals. Furthermore , the mechanism of plant resis2 multistep enzymatic process. The linkage occurs at specif2tance to heavy metals is discussed. ic lysine residues of the acceptor protein with formation ofan isopeptide bond between the carboxyl group of the C- 1 Materials and Methods εterminal glycine of ubiquitin and- NHgroup s of the ly2 2 sine side- chains of the target protein. The conjugation of 111Plant materials and stress conditions ubiquitin to protein may alter their stability or serve as a ( ) Bean Phaseolus vulgaris L . cv. Saxaseeds were recognition signal for proteolysis by the 26 S proteo2 surface- sterilized with a 2 . 5 % calcium hypochloride solu2 1 some .In addition to removing the denatured or abnor2 tion for 10 min , rinsed several times with distilled water() Ξ Supported by the“863”Grant for Youth and the NationalNatural Science Foundation of China No . 39870078. Received : 1999- 01- 14 Revised : 1999- 05- 16and then imbibed in sterile water for 16 h. Germination signal with the control probe . The two clones were sub2 ?after which the young plants were trans2 occurred at 22 ( ) cloned into pBluescript KS + plasmid vector and se2 ferred onto a liquid culture medium containing KNO2 3 quenced by the dideoxy method.( ) mmol/ L , Ca NO2 . 5 mmol/ L , MgSO1 mmol/ L , 3 2 4 113Northern blot analysisKHPO1 mmol/ L and Fe 2 . 8 mg/ L , Mn 0 . 55 mg/ L , 2 4 RNA samples were prepared and analyzed according 6 Zn 0 . 65 mg/ L , Cu 0 . 06 mg/L , B 0 . 32 mg/ L , Mo 0 . to standard protocols, by electrophoresis on 1 . 2 % a2 02 mg/ L . Plants were grown in a growth chamber with a garose-formaldehyde gels , transferring onto Hybond N photoperiod of 16 h at 22 ? during the day and 18 ? membranes , and hybridizing for 24 hin the presence of 6 during the night and a photosynthetic photon flux density ( ×SSC 1 ×SSC : NaCl 0 . 15 mol/ L , CHNaO0 . 15 6 537 32 - 2 - 1 ) μmol/ L- 50 % formamide at 42 ? to P- cDNA probes. When the two primary leaves of 150 mol m? s? .Hybridization was followed by three washes for 15 min were well expanded , plants were stressed by adding one ofeach at 42 ?in 2 ×SSC. Finally , the membrane was ex2the following metals : HgCl, CdCl, CuSOor ZnSOat a 2 2 4 4μposed to X- ray film for autoradiography at - 80 ?.final concentration of 100mol/ L . For other experiments() plants were grown in plots in soilunder the same light- 2 Results dark and temperature conditions. Various types of abiotic PvSR51 encode a polyubiquitin re2 2 . 1 PvSR5 and stress were applied asfollows : leaves were sprayed with a spectively ( ) 0 . 2 % W/ VHgClor CdCl, or 10 mmol/ L salicylic 2 2 analysis showed that PvS R5 clone con2 Sequence ( ) acid SA solution. For heat- shock treatment , plants ( ) tained a 790 bp insert Fig. 1A. Northern blot revealed were placed at42 ? for 4 h , while wounding was per2 7 that PvS R5 mRNA has a size of 1 200 nucleotides, in2 formed by dusting the leaves with celite and gentle rub2 dicating that the cDNA was not full- length. PvS R5 cDNA bing. Leaf tissue was harvested at various time points after contains more than two repeats of ubiquitin coding unit stress treatment . and lacks the 5′end coding sequence , leucine which is 2 bean cD NA li12 Construction and screening of a 1unique non- ubquitin residue at the end of the last ubiqui2 brary tin repeat . Total RNA extraction was done using the phenol/ PvS R51 cDNA is also partial fragment that lacks the 5 chloroform/ isoamylalcohol technique. Polyadenylated 5′coding region.It encodes more than four ubiquitin re2mRNAs were obtained by chromatographing total RNA peats , the terminal repeat contains another additional ( ) twice on oligo- dTcellulose as described by Sambrook ( )amino acid , phenylalanine Fig. 1B. Repeats of 228 nu2 6 et al . Double- stranded cDNA was synthesized from cleotides encoding ubiquitin monomers were aligned below polyadenylated RNA isolated from bean plantsharvested 6 the first complete one taken as an arbitrary reference . Ho2 h after spraying with mercuric choloride solution using the mologies were found to range between 80 % to 90 %. Pharmacia Biotech kit . The cDNA library was constructed There are no homologies in the3′untranslated region be2 λin the bacteriophagegt 10 cloning vector . tween PvS R5 and PvS R51 genes. Therefore , PvS R51 en2 The cDNA clones were placed at a density of about codes a polyubiquitin that isdifferent from PvS R5 . ( ) 1 000 plaques/ dish diameter 9 cm. Duplicate sets of 2 . 2 Expression of PvSR5 gene in various tissues of nitrocellulose filters containing recombinant phage plaques young bean plants 32 were screened with [ P - labelled cDNA probes , pre2 PvS R5 gene is highly expressed in root but weakly pared of using polyadenylated RNAs extracted from mer2 ( ) expressed in stems and leaf tissue Fig. 2. The same curic chloride- treated or untreated bean leaves. Differen2 ( pattern was observed on PvS R51 gene results not tial screening permitted the isolation of clones that were ) shown, demonstrating that polyubiquitin genes are con2 only expressed in mercury- treated plants or that were ex2 stitutively expressed in different tissues. pressed at higher levels in stressed plants than in control PvS R5 gene expres2 Effect of heavy metals on 2 . 3 plants. Both types of clones were considered to be heavy- sion in primary leaves( metal stress- related. 32 positive clones Phaseolus vul2 Theexpression of polyubiquitin gene was studied in ) garis stress- related gene , PvS R were isolated by screen2 response to several metal stresses. More than one hy2 ing of the cDNA library , in which PvS R5 and PvS R51 bridization signals are observed in Fig. 3 , as PvS R5 clones gave a strong hybridization signal with the cDNA probe contains partialubiquitin coding sequence that is probe obtained from mercury- treated plants and a weak植物学报 1054 41 卷() ()Fig. 1 Nucleotide sequence and deduced amino acid sequence of PvS R5 cDNA Aand PvS R51 cDNA B A. The initiation amino acid of the ubiquitin repeats is boxed , asterisk indicates the stop codon. GenBank access number for PvS R5 is U77940. B. The stop codon is indicated by an asterisk and the putative polyadenylation signal is underlined.Nucleotide sequences of the ubiq2 uitin repeats are aligned. Identical nucleotides are indicated by dots. Amino acid sequences are given in the one- letter code below the last u2 biquitin repeat . GenBank access number for PvS R51 is U77939.levels in the leaves , but with a different kinetics of induc2tion from that obtained with sprayed leaves. When mer2curic chloride was absorbed by the roots , PvS R5 mRNAstarted to accumulate at 9 h after the onset of treatment ,( ) reached a maximum at 48 h and then declined Fig. 3C.The transcript level continued to increase from 9 h afterthe onset of treatment until a maximum was reached 48 h( ) later when cadmium was absorbed by the roots Fig. 3D. Root- absorbed copper also stimulated the PvS R5 expres2 Fig. 2 PvS R5 gene expression in various tissues of Phaseolus vul2 garis seedlings sion , the transcripts reached a maximum after 24 h , ( μ) Total RNAs 10 g/ laneextracted from the various tissues of 12( ) whereas zinc had alittle effect Fig. 3 E , F. day-old plants were separated on formaldehyde- agarose gels , trans2 2 . 4 PvSR5 gene regulation by otherf orms of a biotic ferred onto membranes and hybridized with PvS R5 cDNA. R. Root ;S. Stem ; L . Primary leaves. stress Spraying with SA resulted in a large increase in tran2 highly homologous to the other ubiquitin gene . As shown script levels , reached a maximum at 3 h and then de2 in Fig.3A and 3B , the amounts of PvS R5 transcripts in2 ) ( ) (clined Fig. 4A. High temperature 42 ?also stimu2 creased rapidly , reached a maximum at3 h and then de2 ( ) lated strongly PvS R5 gene expression Fig. 4B, PvSR5 creased gradually when the leaves were sprayed with mer2 ( mRNA reached a maximum at 1 h during the stress 4 curic chloride or cadmium chloride solution. When the ) h, and then decreased after plants were returned to nor2 mercuric chloride or cadmium chloride was added to the mal temperature condition. Wounding had almost no effect liquid culture medium instead of being sprayed onto the ( ) PvS R5 gene expression Fig. 4C. on plants , PvS R5 mRNA also accumulated above the basalFig. 3 Northern blots analysis showing the levels of PvS R5 mRNA in bean leaves treated with various metals () () The time course of accumulation of PvS R5 transcripts after the seedlings were treated byvaporization of HgClAand CdClB, or by root- 2 2 ( ) () ( ) ( ) absorption of HgClC, CdClD, CuSOE, and ZnSOF. 2 2 4 4encode a polyubiquitin respectively. Both PvS R5 and 3 Discussion PvS R51 cDNA are incomplete at their 5′end probablySequence analysis showed that PvS R5 and PvS R51 because of inverted repeats in coding regions of ubiquitin genes contained more than two repeats of the ubiquitin mRNAs forming snap back loop structures which are self- 4 coding unit . The additional amino acid residues of both primed during cDNA synthesis. PvS R5 mRNA prefer2 genes encoded are different , PvS R5 terminates at entially accumulated in the root of bean seedling indicat2 leucine , whereas the phenylalanine is found at the C- ter2 ing that polyubiquitin gene has tissue- specific expression. minal of PvS R5 , suggesting that PvS R5 and PvS R51植物学报 1056 41 卷stimulate the expression of PvS R5 , but Cu and Zn had a( ) little effect Fig. 3, demonstrating that Hg and Cd ions are more toxic than Cu and Zn to living cell .PvS R5 gene responds not only to heavy metals , butalso to other stresses such as elevated temperature , 13 12 and virus infection, indicating that the ubiqui2 UVtin pathway has important roles in eliminating the damagedproteins induced by various stresses and maintaining thecell structure and function. Transgenic rice experimentsshowed that polyubiquitin gene expression was limited tothe region exposed to heat stress and/ or wounding , oraround the necrotic lesion induced by pathogen infection , 14 but rather not regulated systemically. This implied thatpolyubiquitins have key roles in the processes of the localdefence reaction. SA is a natural signal in the inductionof defense responses , which accumulates upon ozone or 15 Fig. 4 Northern blot analysis showing the time course of PvS R5 UV treatment , as well as pathogen attack. Exogenous accumulation in bean leaves under various abiotic stresses SA can positively regulate the gene expression of PvS R5 , The arrow on panel B indicates the transfer of the stressed plants to leading to the conclusion that SA might be involved in the normal growth conditions and the time points behind the arrows the duration of recovery. A. Salicylic acid ; B. Heat stress ; C. pathway of polyubiquitin mRNA synthesis in response to Wounding. 16 stresses. Chen et al . proposed that systemically ac2quired resistance signaling is mediated by an accumulation PvS R5 transcripts was detected in un2 A low level ofof HO, because SA specifically binds to catalase and ( ) stressed bean leaves Fig. 3, but the gene expression was 22 2 + 2 + inhibits its activity , leading to an elevation of HOlevel . ( 22 strongly stimulated by heavy metals Hg, Cdand 2 + Furthermore , HOinduces expression of defense- related 22 ) Cu. The datum is consistent with the responses of genes. A rapid and transient release of active oxygen polyubiquitin genes to mercuric stress in maize and tobac2 9 3 ,4 () species AOScan be induced by heavy metals, UV , , suggesting that polyubiquitin may playan impor2 co 16 17 pathogen infection, SA and heat stress. These re2tant role in resistance to heavy metals. Heavy metal ions sults suggest that PvS R5 gene expression was possibly in2 can bind to protein sulfhydryl group s , leading to deficien2volved in the regulation of AOS in response to stresses , cy of essential ions and destruction of the enzyme struc2 8 ,9 and there may be a common signal transduction pathway ture . Other toxicity mode is oxidative damage by free 9 ,10for various stresses in the regulation of PvS R5 gene ex2 radicals generated by metal redox cycling . Eventual2 pression. ly , the two processes result in accumulating huge amount of denatured and damaged proteins by metals in the cell .References In eukaryotes , an important selective proteolysis pathway for the elimination of abnormal proteins that are generated Belknap W R , Garbarino J E. The role of ubiquitin in plant 1 senescence and stress responses. Trends Plant Sci , 1996 , 1 : under normal or stress conditions is ATP- dependent and 2 331,335 mediated by ubiquitin system. The ubiquitin monomers generated by UbEP genes act as a molecular“chaperone” Tanaka K. Proteasones : Structure and biology. J Biochem , 21998 , 123 : 195,204in facilitating ribosome assembly. In contrast , the polyu2 Didierjean L , Frendo P , Nasser W , Geneviève G , Marivet J , 3 biquitin genes would provide monomers for general utiliza2 Burkard G. Heavy metal- responsive genes in maize : Identifi2 1 ,2 tion inubiquitin- mediated processes in cell. In cation and comparison of theirexpression upon various forms of yeast , the expressions ofpolyubiquitin and ubiquitin- con2 abiotic stress. Planta , 1996 , 199 : 1,8jugating enzyme genes are activated in response to cadmi2 4 Genschik P , Parmentier Y , Durr A , Marbach J , Criqui M C.um exposure and the mutants deficient in specific ubiqui2 Ubiquitin genes are differentially expressed in protoplast- de2rived cultures of Nicotiana sylvestris and in response to varioustin- conjugating enzymes are hypersensitive to cadmium , stresses. Plant Mol Biol , 1992 , 20 : 897,910 proposed that cadmium resistance is meditated partially by 11 Ragueh F , Lescure N , Roby D , Marco Y. Gene expression in 5 ubiquitin pathway. PvS R5 mRNA levels are increased Nicotiana tabacum in response to compatible and incompatible upon treatment with metals , implying that enormous ubiq2 isolates of Pseudomonas solanacearum . Physiol Mol Plant uitin monomers are required for degrading the abnormal Pathol , 1989 , 35 : 23,33 proteins produced by metals. Hg and Cd can strongly 6 Sambrook J , Fritsch E F , Maniatis T. Molecular Cloning : A() ()Laboratory Manual . 2nd ed. New York : Cold Spring Harbor 生物物理学报,1998 , 14 : 767,771 in Chinese() ( ) 13 Zhang Y- X张玉秀, Chai T- Y柴团耀. Effects of alfalfa Laboratory Press , 1989.) ( ) ( 7 柴团耀 , Zhang Y- X 张玉秀 , Burkard G. Chai T- Y mosaic virus infection on the expression of stress- responsiveHeavy metal- responsive genes in bean : cloning of cDNAs and ()genes in bean. Acta Hort Sin 园艺学报,1998 , 25 : 399,(()gene expression analysis. Acta Phytophysiol Sin 植物生理学 401 in Chinese ) ()14 Takimoto I , Christensen A H , Quail P H , Uchimiya H , Toki 报, 1998 , 24 : 399,404 in ChineseS. Non- systemic expression of a stress- responsive maize polyu2 8 Van Assche F , Clijsters H. Effects of metal on enzyme activity in plants. Plant Cell Environ , 1990 , 13 : 195,206 () biquitin gene Ubi-1in transgenic rice plants. Plant Mol Bi2 ( ) ( ) Zhang Y- X 张玉秀 , Chai T- Y 柴团耀 , Burkard G. ol , 1994 , 26 : 1007,1012 9 (Heavymetal tolerance mechanisms in plants. Acta B ot Sin 植 Ec Key- Kaltenbach H , Kiefer E , Grosskopf E , Ernst D , San2 15 ) ()物学报, 1999 , 41 : 453,457 in Chinese dermann H. Differential transcript induction of parsley patho2 González A , Steffen K L , Lynch J P. Light and excess man2genesis- related proteins and of a small heat shockprotein by o2 10 ganese implications for oxidative stress in common bean. Plant zone and heat shock. Plant Mol Biol , 1997 , 33 : 343,350 Physiol , 1998 , 118 : 493,50816 Chen Z , Silva H , Klessig D F. Active oxygen species in the J ungmann J , Reins H A , Schobert C , J entsch S. Resistance to 11 induction of plant systemic acquired resistance by salicylic cadmium mediated by ubiquitin- dependent proteolysis. N a2 acid. Science , 1993 , 262 : 1883,1886 ture , 1993 , 361 : 369,371 17Dat J F , Lopez- Delgado H , Foyer C H , Scott I M. Parallel () () (Chai T- Y柴团耀, Zhang Y- X张玉秀, Zhang Z- D 张正 changes in HOand catalaseduring thermotolerance induced 12 22 ) 东. Effects of elevated ultraviolet radiation on the stress- re2 by salicylic acid or heat acclimation in mustard seedlings. sponsive gene expression of bean seedling. Acta Biophys Sin Plant Physiol , 1998 , 116 : 1351,1357。
利用作物生长模型和时序信号甄别水稻镉胁迫
第37卷第4期农业工程学报 V ol.37 No.42021年2月Transactions of the Chinese Society of Agricultural Engineering Feb. 2021 249 利用作物生长模型和时序信号甄别水稻镉胁迫孔丽，刘美玲※，刘湘南，邹信裕（中国地质大学（北京）信息工程学院，北京 100083）摘要：在自然农田生态系统中，农作物的生长通常受到各类环境胁迫（如重金属胁迫、病虫害、水分、营养）的影响，如何区分重金属胁迫与其他胁迫有待进一步研究。
该研究选取了湖南省株洲为试验区，收集2017—2019年的Sentinel-2卫星影像数据，结合野外实测数据，开展水稻重金属镉（Cd）胁迫识别研究。
首先，利用作物生长模型World Food Studies （WOFOST）同化时序遥感数据获取每年的叶面积指数（Leaf Area Index，LAI）时间序列曲线；然后运用集合经验模态分解（Ensemble Empirical Mode Decomposition，EEMD）方法对LAI时间序列进行多尺度分解，得到不同的时序信号分量（Intrinsic Mode Function，IMF）；最后使用动态时间规整（Dynamic Time Warping，DTW）方法计算受胁迫水稻分解后的时间序列与健康水稻分解后的时间序列之间的DTW距离，即归一化胁迫指数。
结果表明：归一化胁迫指数是水稻重金属胁迫敏感的参数，与土壤重金属含量的相关系数为0.851，水稻受到的胁迫程度越高，归一化胁迫指数值越大，反之越低；在试验区中，水稻重度重金属胁迫的分布面积比例相对较低，且主要集中在西部、东北部以及偏东南地区。
融合集合经验模态分解和动态时间规整方法能有效地甄别并定量分析水稻重金属胁迫状况，从而为作物重金属污染胁迫监测提供重要参考。
关键词：遥感；模型；重金属；镉胁迫；时序信号分解；WOFOSTdoi：10.11975/j.issn.1002-6819.2021.04.030中图分类号：S127 文献标志码：A 文章编号：1002-6819(2021)-04-0249-08孔丽，刘美玲，刘湘南，等. 利用作物生长模型和时序信号甄别水稻镉胁迫[J]. 农业工程学报，2021，37(4)：249-256.doi：10.11975/j.issn.1002-6819.2021.04.030 Kong Li, Liu Meiling, Liu Xiangnan, et al. Identifying heavy metal (Cd) stress in rice using time-series signals and crop growth model[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(4): 249-256. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2021.04.030 0 引 言随着经济的不断发展，工业化不断推进，土壤重金属污染成为当今世界面临的重大生态环境问题之一[1]。
印度芥菜_BrassicajunceaL__重金属耐性机理研究进展
中国生态农业学报 2011年1月 第19卷 第1期Chinese Journal of Eco-Agriculture, Jan. 2011, 19(1): 226−234* 国家高技术研究发展计划(863计划)项目(2007AA021404, 2006AA10Z407)和转基因生物新品种培育科技重大专项(2009ZX08009-130B) 资助** 通讯作者: 柴团耀(1960~), 男, 教授, 博士, 主要研究方向为植物抗逆分子生物学。
E-mail: tychai@ 孙涛(1979~), 男, 博士研究生, 研究方向为植物基因表达调控。
E-mail: suntao07b@DOI: 10.3724/SP.J.1011.2011.00226印度芥菜(Brassica juncea L .)重金属耐性机理研究进展*孙 涛1 张玉秀2 柴团耀1**(1. 中国科学院研究生院生命科学学院 北京 100049; 2. 中国矿业大学(北京)化学与环境工程学院 北京 100083)摘 要 印度芥菜可富集/忍耐Cd 、Zn 等多种重金属, 是研究植物修复技术的一种模式植物。
高浓度的重金属离子会改变植物的基因表达、细胞形态、细胞结构, 最终使植物生长受抑, 甚至死亡。
印度芥菜高效的抗氧化系统、损伤修复系统以及对重金属的螯合、区域化可部分解除重金属的毒性, 缓解重金属离子的毒害作用。
利用基因工程技术在印度芥菜中导入重金属耐性及运输相关基因可大幅度提高其重金属富集能力, 在重金属污染修复方面具有广阔的应用前景。
关键词 印度芥菜 重金属胁迫 超富集植物 植物修复技术 抗氧化系统 中图分类号: X53 文献标识码: A 文章编号: 1671-3990(2011)01-0226-09Research progress on tolerance of Indian mustard (Brassica juncea L .)to heavy metalSUN Tao 1, ZHANG Yu-Xiu 2, CHAI Tuan-Yao 1(1. College of Life Science, Graduate University of Chinese Academy of Sciences, Beijing 100049, China; 2. School of Chemicaland Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China)Abstract Much research has been conducted on the mechanism of phytoremediation of heavy metal pollution by Indian mustard. Indian mustard plants typically have high heavy metal (e.g. Zn and Cd) accumulation capacity. Changes had been noted in plant gene expression, cell morphology and cell structure under high heavy metal concentration, which eventually resulted in growth inhibition and even death. In Indian mustard, high efficient antioxidant system, injury-repairing system and chelation, compartmentalization for heavy metals could detoxicate the toxicity of heavy metals and alleviate the injury induced by heavy metals. Transgenic Indian mus-tard with tolerance or transport genes improved heavy metal accumulation ability. This implied that Indian mustard had a great poten-tial for phytoremediation of heavy metal contaminated soils.Key words Indian mustard, Heavy metal stress, Hyperaccumulator, Phytoremediation, Antioxidant system (Received May 1, 2010; accepted Aug. 13, 2010)植物对非生物胁迫所具有的耐性可使其适应一些极端苛刻的环境, 土壤重金属污染就是植物所必须面临的一种非生物胁迫[1]。
英语资讯：农业废弃物变成黄金
Reporter: China produces more than 800 million tonnes of crop straw and stover every year.In the past, most of this biomass had been burnt in open fires resulting in heavy air pollution.Although scientists and engineers have found other profitable uses for these tonnes of agricultural waste, like generating bio-fuel or using them as building materials, many farmers are still unaware of how to make money with it.The International Green Economy Association, a Beijing-based NGO, is taking action to tackle the problem.Deng Jihai is the Secretary-General of the association."Our research findings show that those regions that have a high rate of crop straw utilization actually have very low-levels of efficiency, and this has slowed down the rate of GDP growth. Hence, the biggest most important focus of our action plan is to make this industry more profitable, making organic waste processing a key sector of the green economy."It is estimated that if China could reduce crop straw burning by 200 million tons each year, it would lead to a drop of carbon dioxide emissions by about 214 million tons. A large scale reduction in straw burning activities could also reduce the possibility of fire hazards, further saving an estimated 100 billion yuan.On the other hand, if crop straw can be processed and used in the manufacturing of biodiesel, organic fertilizer, bio-feed and even used to as a building material instead of wood, this could help to increase a farmer's income by 1800 to 2400 yuan per acre of cropland.The International Green Economy Association is determined to assist farmers to convert their agricultural waste into clean bio products.Deng Jihai explains:"This year, we'll accelerate to develop the industry of comprehensive utilization of crop straw. This project aims not only to tackle the soil erosion and air pollution issues, including smog, as a result of crop straw burning, but develop it into a new industry instead of mere utilization."A conference on the industrial development of crop straw resources' will be held in Ulanhot in Inner Mongolia in mid-June. It will bring together high-tech enterprises and agricultural scientists from China and abroad to come up with effective ways to turn agricultural waste recycling into a thriving industry.For China Drive, I'm Xu Fei.更多英语学习方法：外贸英语学习/study-trade.html。
超富集植物吸收富集重金属的生理和分子生物学机制
超富集植物吸收富集重金属的生理和分子生物学机制3李文学 陈同斌33(中国科学院地理科学与资源研究所环境修复室,北京100101)【摘要】 与普通植物相比,超富集植物在地上部富集大量重金属离子的情况下可以正常生长,其富集重金属的机理已经成为当前植物逆境生理研究的热点领域.尤其是近两年,随着分子生物学等现代技术手段的引入,关于重金属离子富集机理的研究取得了一定进展.通过与酵母突变株功能互补克隆到了多条编码微量元素转运蛋白的全长cDNA ;也从分子水平上研究了谷胱甘肽、植物螯合素、金属硫蛋白、有机酸或氨基酸等含巯基物质与重金属富集之间的可能关系.本文从植物生理和分子生物学角度简要评述超富集植物对重金属元素的吸收、富集、螯合及区室化的机制.关键词 超富集植物 重金属 生理学机制 分子生物学机制文章编号 1001-9332(2003)04-0627-05 中图分类号 X171.5 文献标识码 APhysiological and molecular biological mechanisms of heavy metal absorption and accumulation in hyperaccu 2mu altors.L I Wenxue ,CHEN Tongbin (L aboratory of Environmental Remediation ,Institute of Geographical Sciences and N atural Resources Research ,Chinese Academy of Sciences ,Beijing 100101,China ).2Chin.J.A p 2pl.Ecol .,2003,14(4):627～631.In comparison with normal plants ,hyperaccumulators have the ability to accumulate heavy metals in their shoots far exceeding those observed in soil ,without suffering from detrimental effects.With the help of molecular tech 2nologies ,the research on the mechanisms of heavy metal accumulation in hyperaccumulators has been made a great progress.A number of trace element trans porters have been cloned by functional complementation with yeast mutants defective in metal absorption.The relations between glutathione ,phytochelatins metallothioneins ,organic acids and heavy metals have been studied by molecular technologies.This review concentrated on the physiological and molecular mechanisms of heavy metal absorption and sequestration in hyperaccumulators.K ey w ords Hyperaccumulator ,Heavy metal ,Physiological mechanisms ,Molecular biological mechanisms.3国家自然科学基金项目(40071075)、中国科学院知识创新工程重点方向项目(K Z CX 22401202)和王宽诚博士后工作奖励基金资助.33通讯联系人.E 2mail :chentb @ 2002-07-05收稿,2002-11-28接受.1 引 言土壤重金属污染是一个重要的环境问题,传统的治理主要采用物理或化学方法,费用高,对大面积的污染效果差;与传统措施相比,植物修复技术以成本低、操作简单等优点而倍受青睐.广义上的植物修复是指利用植物去除土壤、水体或空气中重金属、有机污染物等污染物的技术,包含植物萃取(Phytoextraction )、根际过滤(Rhizofiltration )、植物挥发(Phytovolatilization )、植物固定(Phytostabilization )等技术,现在通常提到的植物修复主要是指植物萃取[32].超富集植物(Hyperaccumulator )是植物修复的基础,国际上已发现400多种超富集植物,国内对于超富集植物的研究相对较晚,研究较为系统的当属As 、Zn 等重金属的超富集植物[2,3,33].与普通植物相比,重金属离子进入超富集植物体内同样经过吸收/转运、富集/转化/矿化等生理生化过程,而且许多重金属离子进入植物体内的离子通道与必需营养元素相同,这就决定了超富集植物必然具有独特的生理代谢过程.关于这些过程的研究已经成为新的研究热点.本文对有关超富集植物吸收和富集重金属离子的生理及分子机制研究进行评述.2 重金属离子吸收的分子生物学机制 遏蓝菜属(Thlaspi L.)植物具有非常强的富集Zn 的能力,能够在地上部富集高达3%(干重)的Zn ,同时植物正常生长,没有表现出任何中毒症状,它已经成为研究重金属富集机理的模式植物之一.但无论是超富集植物或是普通植物,金属离子进入植物体内的第一步是根系吸收,也就是说吸收过程很可能是超富集植物富集重金属离子的第一个限速步骤.T.caerulescens 与T.arvense 同属于遏蓝菜属,T.caerulescens 能够富集Zn 而T.arvense 则不具此能力,通过比较它们对Zn 2+的吸收动力学发现:两者Km 值差异不大,但T.caerulescens 的Vmax 要比T.arvense 高3.5倍[21],表明T.caerulescens 富集Zn 2+的能力并非是与Zn 2+有更高的亲和力,而很可能是因为锌离子的流入量加大所致,也就是说在T.caerulescens 根系细胞膜上分布有更多的锌离子转应用生态学报 2003年4月 第14卷 第4期 CHIN ESE JOURNAL OF APPL IED ECOLO GY ,Apr.2003,14(4)∶627～631运蛋白.近年来随着分子生物学等现代技术手段的引入,人们对金属离子如何进入细胞有了新的认识.通过对酵母突变株进行功能互补克隆到了多条编码微量元素转运蛋白的全长cDNA,其中研究最多的是ZIP基因家族(ZRT,IRT-like Protein).ZIP基因家族分布非常广泛,在真菌、动物、植物等真核细胞中均发现了ZIP基因家族成员.ZIP基因编码的蛋白一般具有8个跨膜区,C2端和N2端的氨基酸均位于细胞膜外.此家族包含至少25个成员,z rt1、z rt2(zinc2regulated transporter)和irt1(iron2regulated transporter)是最早克隆到的ZIP基因.z rt1、z rt2均由酵母中获得,与Zn的吸收密切相关[36,37];irt1编码的蛋白主要位于拟南芥的根系,体内缺Fe时可诱导irt1表达[8].另一类与金属离子吸收有关的蛋白是Nramp基因家族(Natural resistance associated macrophage proteins).Nramp基因家族编码的蛋白一般具有12个跨膜区,这与ZIP基因家族明显不同.Nramp最初在哺乳动物中发现,植物中的研究主要集中于水稻(Oryz a sativa)和拟南芥(A rabidopsis).O2 ryz a sativa和A rabidopsis的Nramp基因家族分为2类,Os2 Nramp1、OsNramp3和AtNramp5属于一类,OsNramp2、At2 Nramp1、AtNramp2、AtNramp3与AtNramp4属于另一类. Nramp基因家族在植物中的功能现在仍不清楚,AtNramp3和AtNramp4能够维持A rabidopsis体内铁离子的平衡[29].此外,AtNramp3很可能与Ca2+的吸收有关,破坏AtNramp3基因可增加植物对Cd的耐性,过量表达则导致植物对Ca2+的超敏感性.对于超富集植物而言,Zn的吸收过程研究相对较清楚.通过与酵母突变株进行功能互补,Pence等[24]在具有富Zn 能力的T.caerulescen中克隆到z nt1.z nt1编码Zn2+转运蛋白,属ZIP基因家族,缺Zn和Zn供应充足条件下均可以在根系和叶片中高量表达,表明其可能是组成型表达;对于不具有富Zn能力的T.arvense而言,z nt1主要在缺Zn件下表达,供Zn时,表达明显受到抑制.这种表达方式的不同很可能是造成Thlaspi富Zn能力差异的主要原因之一.Assun2 cao等[1]的研究结果也表明Zn转运蛋白基因T.caerulescen 的表达量要远高于T.arvense.从Pence等[24]、Assuncao等[1]与Lasat等[21]的实验结果可以发现根系Zn转运蛋白基因的表达量与Thlaspi富集Zn的能力正相关,初步验证了吸收过程是超富集植物富集重金属离子的首个限速步骤的假设.但是目前还不能肯定转运蛋白是否在超富集植物吸收重金属方面起到决定性作用.譬如说,尽管z nt1、z nt2在T. caerulescen的表达量要远高于T.arvense,但是它们在具有不同富集能力T.caerulescen中的表达量几乎相同[1],即T.caerulescen富集能力的差异与吸收并无太大的相关性.造成此现象的原因很可能在于:(1)一般来说,转运蛋白由一个基因家族控制,而现在得到的克隆还不足以代表整个家族,许多未知的基因可能起到更为重要的作用,如在T. caerulescen就又克隆到z at基因,它与Zn2+的区室化(Se2questration)密切相关,但是此基因与ZIP基因家族明显不同,仅含有6个跨膜区[34];(2)对已知转运蛋白的性质研究还不清楚,金属离子转运蛋白对底物专一性不强,造成多种吸收途径同时对一种金属离子发挥作用,所以在进行具体的分子生物学研究时,必须清楚那些转运蛋白对该金属离子起作用;(3)现在转运蛋白的研究主要集中于根系,叶片中转运蛋白的研究相对较少,但是对超富集植物而言,重金属离子在地上部的含量要远远高于根系,即叶片中的转运蛋白很可能起到更为主要的作用.3 木质部运输 在木质部存在大量的有机酸和氨基酸,它们能够与金属离子结合,这种复合物是重金属离子在木质部中运输的主要形式.譬如在木质部,Fe主要是以柠檬酸铁的形式存在,Zn 主要是与柠檬酸或苹果酸结合,而Cu随着植物不同可与天冬酰胺酸、谷氨酸、组氨酸或烟碱结合,当然也有许多是以离子形态存在的,如Ca、Mg、Mn.在超富集植物中研究较多的为组氨酸.Kramer等[19]发现,组氨酸与A lyssum montanum 富集Ni的能力密切相关,当植物地上部Ni含量高时,木质部中组氨酸含量也较高,外源组氨酸的加入也能显著促进Ni装载入木质部,从而提高Ni向地上部的运输.然而,最近的研究表明,组氨酸反应很可能并不是Ni超富集植物的普遍机理.Persans等[25]在研究Ni的超累积植物Thlaspi geosingense时并没有发现His反应,同时他们克隆了控制His 合成的关键酶基因thg1、thb1、thd1,其表达量并没有随着Ni用量的增加而升高. 重金属由根系进入木质部至少需要3个过程:进入根细胞,由根细胞运输到中柱,装载到木质部.在内皮层由于凯氏带的存在,使得共质体运输在重金属进入木质部的过程中起到主导作用.在共质体运输中起关键作用的是膜转运蛋白,然而直到现在还没有在木质部中克隆到与重金属离子运输相关的基因,这方面的研究,尤其是在研究超富集植物时应该引起充分的重视.与普通植物相比,超富集植物能够高效、迅速地把重金属离子由根系运输到地上部,而通过凯氏带是重金属离子进入木质部主要屏障之一,探明此过程,将有利于提高植物修复的效果.4 对金属离子的解毒机制411 谷胱甘肽(GSH) 许多金属离子是植物必需的微量养分,它们参与植物体内众多的生理代谢过程.但如果含量过高,尤其是具有氧化还原活性的金属,会对植物产生毒害作用,这种毒害作用很可能是由于自由基的形成造成的.GSH含巯基,具有很强的氧化还原特性,可有效地清除活性氧等自由基,因此GSH在植物抗逆境胁迫中起重要作用.GSH为三肽,结构通式为γ2 G lu2Cys2G ly,合成主要通过两步依赖于A TP的反应完成,γ2 EC合成酶和GSH合成酶是其中的关键酶.γ2EC合成酶由gsh1编码,GSH合成酶由gsh2编码,gsh1与gsh2在拟南芥826应 用 生 态 学 报 14卷基因组中均以单拷贝的形式存在. 正常条件下,GSH的合成依赖于半胱氨酸的活性,同时存在明显的反馈抑制现象,表明由γ2EC合成酶催化的反应是整个合成的限速步骤.重金属胁迫条件下,重金属离子激活植物螯合素的合成,消除了GSH的反馈抑制作用,由GSH 合成酶催化的反应也成为限速步骤,此时如果加强gsh2的表达,则既可增加植物螯合素的合成又能避免GSH的耗竭,从而缓解重金属胁迫.Zhu等[38,39]的实验结果验证了此假设.他把大肠杆菌的gsh1与gsh2分别转入到印度芥菜(B rassica juncea),发现印度芥菜对Cd2+的耐性与富集能力均有明显增加,且耐性和富集能力还与gsh2的表达正相关.然而,Foyer等[10]把gsh2转入白杨树(Populus)后,白杨树抗氧化胁迫的能力(光抑制)并没有增加;G oldsbrough等[13]的结果也表明gsh2转入野生型的拟南芥后并不能增加其对Cd的抗性.由此可见,如何通过基因工程改造GSH,以增加植物对重金属的耐性和富集能力还有待于进一步研究.412 植物螯合素(PCs) 植物螯合素(PCs,=cadystins in S.pombe)由植物体内一系列低分子量、能够结合金属离子的多肽组成,其结构通式为(γ2G lu2Cys)n2G ly(图1),一般来讲,n为2～5,最高可达11[5].现已发现多种PC的同功异构体,主要是C端的G ly 被β2Ala、Ser取代形成.原来认为植物螯合素仅存在于植物中,但是随着研究的深入,陆续在线虫、蚯蚓等克隆到PC合成酶的类似基因. PCs不能由基因直接编码,必须在PCs合成酶的催化下完成[14].PC合成酶为四聚体,分子量95000道尔顿,等电点在p H4.8附近,最适反应温度和p H分别为35o℃、7.9[14].然而,由克隆到的编码PCs的全长cDNA推测的结果与此不符,推测结果表明PCs不是多聚体,分子量为42000～70000道尔顿,这种偏差很可能由于在Grill等提纯的酶中PCs并不是主要成分造成的.不同重金属离子诱导PCs合成的能力有很大差别[15],一般为Cd2+>Pb2+>Zn2+>Sb3+>Ag+> Hg2+>As5+>Cu+>Sn2+>Au3+>Bi3+;不同重金属离子诱导PC合成酶活性的能力与诱导PCs合成的能力稍有不同[35]:Cd2+>Ag+>Pb2+>Cu+>Hg2+>Zn2+>Sn2+> Au3+>As5->In3+>Tl3+>G e4+>Bi3+>G a3+.关于PCs 功能研究得相对清楚的是PCs与Cd之间的关系(图2).现图1 植物螯合素的化学结构示意图Fig.1Chemical structure of phytochelatin.已明确PCs在植物解Cd毒中起到重要作用,PCs2Cd复合物是Cd由细胞质进入液泡的主要形式.正是由于PCs在重金属离子区室化中所起的重要作用,近年来PCs已成为植物抗重金属胁迫的研究热点之一. 目前PCs的分子生物学研究基本集中于普通植物或耐性植物,而有关超富集植物的研究相对较少.Schmoger等[28]在用As处理过的蛇根木(Rauvolf ia serpentina)悬浮细胞及拟南芥幼苗中发现了PCs,Hartley2Whitaker等[17]在绒毛草(Holcus lanatus)上也证实了上述现象.但这些植物多属于耐性植物.Ebbs等[7]的实验表明,无论是否具有富集能力, Thlaspi用Cd处理后都会有大量PCs的合成,但是T.ar2 vense中PCs的总量要高于T.caerulescens,说明PCs与植物富Cd能力之间并无太大的关系.由于PCs在超富集植物中的研究还很少,所以PCs在超富集植物是否起到重要作用还有待于深入研究. Cobbett、Rea和等3个研究小组于1999年分别在拟南芥、小麦、酵母中克隆到了编码PC合成酶的全长cDNA.其中,通过对拟南芥cad1突变株(含有与野生型相似的GSH含量,但不含PC)定位克隆获得At PCS1[16],小麦耐Cd基因At PCS1与TaPCS1主要是通过与酵母突变株功能互补得到[4,30].对PC合成酶相应的全长cDNA对齐比较发现其保守区位于N端,同一性高达40%.长时间Cd2+处理cad1突变株也没有发现PCs的合成,表明PCs的合成可能是由单基因控制[18].但随着拟南芥基因组测序的完成,发现了与At PCS1高度同源的At PCS2基因[16],其功能尚不清楚,但与At PCS1相比,其表达量非常低.但植物在长期的进化历程中把At PCS2作为功能基因保留下来,尽管其在正常条件下表达量很低,可以想象在某些器官或环境下,At PCS2基因的表达肯定会起到重要作用.图2 以Cd为例说明谷胱甘肽、植物螯合素在抗重金属胁迫中的作用(+表示增加基因表达或酶活性,-表示减少基因表达或酶活性, HM T1表示位于液泡膜上的PC2Cd转运蛋白),参见Cobbert[5]并作修改Fig.2Function of GSH and PC in the metal tolerance of plants under metal stress(+and2indicate positive and negative regulation of enzyme activities or gene expression,respectively;HM T1is a vacuolar meme2 brane transporter of PC2Cd complex;revised from the figure of Cob2 bert[5]).413 金属硫蛋白(M T) 金属硫蛋白(Metallothioneins)是自然界中普遍存在的一种低分子量、富含半胱氨酸的蛋白质.它与PCs的本质区别在于M T由基因直接编码,而PCs在PCs合成酶的催化下完成.与PCs一样,金属硫蛋白能够通过巯基与金属离子结合,从而降低重金属离子的毒性,它对于Zn2+和Cu2+的解毒效9264期 李文学等:超富集植物吸收富集重金属的生理和分子生物学机制 果尤为明显[23]. 植物中首先鉴定的M T是Ec蛋白,它由小麦成熟胚芽中分离得到.在植物中已发现大约50种M T,根据半胱氨酸残基的排列方式,可以将其分为Ⅰ型、Ⅱ型、Ⅲ型和V型,大多属于Ⅰ型和Ⅱ型.Ⅰ型中的半胱氨酸残基仅有Cys2Xaa2 Cys一种排列方式;Ⅱ型中的半胱氨酸残基有两种排列方式,分别为Cys2Cys、Cys2Xaa2Xaa2Cys.编码I型M T的cDNA 在根系的表达水平较高,编码Ⅱ型M T的cDNA主要在叶片表达. 金属硫蛋白极易水解,尤其植物中的金属硫蛋白氨基酸链比较长,极易在半胱氨酸区水解,同时金属硫蛋白在有氧的条件下非常不稳定,所以难以获得相应蛋白质的资料,目前仅对小麦Ec蛋白及拟南芥M T1、M T2编码的蛋白进行了纯化,这就限制了对M T类似基因功能的研究.Murphy 等[22]证实Cu2+诱导拟南芥M T2表达,而且表达强度与不同基因型抗Cu胁迫的能力密切相关;Nathalie等[13]的研究结果也证实Cu的耐性植物Silene v ulgaris耐Cu胁迫的特性与M T2b的表达紧密联系.王剑虹等[31]在重金属耐性植物紫羊茅草(Festuca rebra)中克隆到mc M T1的全长cD2 NA,此基因编码70个氨基酸,含有12个Cys残基,在N端和C端分别含有3个Cys2Xaa2Cys结构,将此基因转入到酵母M T基因缺失突变株中发现,mc M T1的表达增加了酵母细胞对Cu、Cd和Pb的抗性.在拟南芥和蚕豆中,M T主要在毛状体中表达[9,12],而Cd等许多有毒重金属离子也在毛状体中累积[27],暗示M T和重金属累积有某种联系.414 细胞壁的固持与区室化作用 植物细胞壁残基对阳离子有高亲和力,可以影响重金属离子向细胞内扩散速率,从而影响金属离子的吸收.比较黄花茅(A nthox anthum odoratum)悬浮细胞和原生质体固Pb 能力发现,Pb浓度对从耐Pb细胞克隆分离的悬浮细胞无太大影响,而原生质体的死亡率上升,相应地,从Pb敏感细胞克隆分离的悬浮细胞和原生质体对Pb极其敏感,表明细胞壁在A nthox anthum odoratum抗Pb胁迫中起到重要作用[26].需要明确的是,细胞壁对金属的固定作用不是一个普遍的抗金属毒害的机制,例如抗Zn毒和Zn敏感型菜豆的细胞壁物质表现出相似的亲和力,同时细胞壁有一定的金属容量,而超富集植物能够在地上部富集大量的重金属离子,暗示细胞壁不可能在超富集植物中起到重要作用.最近的研究表明,区室化作用与超富集植物富集重金属离子的能力密切相关.就Thlaspi而言,具有富集能力的T.geosingense液泡中Ni的含量要比不具有富集能力的T.arvense高1倍[20]; Frey等[11]也证实Zn在T.caerulescens中主要分布于表皮细胞液泡中.但区室化作用是否为超富集植物富集重金属离子的一个普遍机理还需对新发现的超富集植物进一步研究才能确定.5 研究展望 关于超富集植物富集重金属离子的研究虽然取得了一定进展,但至今对其分子和生理机制仍不是很清楚,研究人员的看法也存在明显的分歧.在把超富集植物用于实践的过程中,首先要研究清楚对超富集植物富集的生理基础,譬如重金属离子如何进入根细胞,在木质部如何被运输,在叶片中如何分布;其次要注意不同生理过程的联系,就吸收而言,它其实是根系吸收与体内再分配的有机结合,所以在利用基因工程方法增加重金属离子吸收量时,不仅要考虑到增加根系的吸收位点,提高转运蛋白底物的专一性,同时要注意细胞器,尤其是液泡膜上与重金属离子区室化相关膜蛋白的表达,只有这样,才会达到比较好的效果;最后要强调的是学科交叉与渗透,Dhankher等[6]将细菌中的砷酸盐还原酶ArsC 基因和γ2谷氨酰半胱氨酸合成酶(γ2ECS)在拟南芥的叶子中表达,这样运输到地上部的砷酸盐在砷酸盐还原酶的作用下转化成亚砷酸盐,γ2ECS表达可增加一些连接重金属(如亚砷酸盐)并解除其毒性的化合物,将这些复合物限制在叶子中,从而使植物能够积累并忍耐不断增加的As含量.参考文献1 Assuncao A G L,Martins PDC,Polter SD,et al.2001.Elevated expression of metal transporter genes in three accessions of the met2 al hyperaccumulator Thlaspi caerulescens Plant Cell Envi ron,24: 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encodes the low affinity zinc transporter in S accaromyces cerevisiae.J Biol Chem,271: 23203～2321038 Zhu Y L,Pilon2Smits EAH,Jouanin L.1999.Overexpression of glutathione synthetase in Indian mustard enhances cadmium accu2 mulation and tolerance.Plant Physiol,119:73～7939 Zhu Y L,Pilon2Smits EAH,Tarun AS,et al.1999.Cadmium tol2 erance and accumulation in Indian mustard is enhanced by overex2 pressingγ2glutamylcysteine synthetase.Plant Physiol,121:1169～1177作者简介 李文学,男,1973年生,博士后.主要从事植物营养遗传与重金属污染生态学研究,在国内外发表论文8篇. E2mail:liwx@1364期 李文学等:超富集植物吸收富集重金属的生理和分子生物学机制 。
Heavy Metal Pollution and Ecological Risk Assessme
Heavy Metal Pollution and Ecological Risk Assessment of Cultivated Land Soil in the Farming Areas of Coastal China: A Case Study of Donghai County, Jiangsu Province 作者：Ligang LYU Xiaorui WANG Xueyan SUI Zhenyu LIU Yong YUAN Chen LIN来源：《农业生物技术（英文版）》2018年第06期Abstract;Classical statistics ， Inverse Distance Weighted and Hakasnson potential ecological index were used to study the distribution characteristics of 8 kinds of heavy metals （Cr ， Ni ， Cu ，Zn， As， Cd， Pb and Hg） as well as their potential ecological risks in the topsoil （0-20 cm） of cultivated land in Donghai County， a typical agricultural area along the Southeast Coast of China. The results showed that the average content of heavy metals in the cultivated soil of Donghai County was not over the risk screening values set in the Environmental Quality Standard for Soils. However， it was worth noting that in some of the sampling points， the content of Cr exceeded the risk screening value， and the standard exceeding points accounted for 24.74% of the total. In addition， the average content of Cr， Ni， As， Cd， Pb and Hg exceeded the soil background values of Jiangsu Province， and values for Cd， Cr and Pb were more than 1.5 times of the soil background value of Jiangsu Province. The heavy metals were at the medium integrated potential ecological risk level， and the potential ecological risk indices were high in the east and low in the west， and distributed in interlaced island shape. The potential ecological risk indices of the plains in the east were higher than those of the central gentle slope area and the western hillock area. The potential ecological risk was at a high level in Niushan Town which was situated the county center and in some regions with high urbanization levels.Key words;Heavy metal contamination; Cultivated land; Ecological risk assessment; Farming area; Donghai CountyThe accumulation of heavy metals in cultivated land not only reduces the yield and quality of crops[1-2]， but also seriously threatens the safety of ecosystems and humans. Anthropogenic sources are the main source of heavy metal pollution in soil， mainly including fertilization， animal wastes and biosolids application， sewage irrigation， atmospheric deposition and so on[3-5]. Industrial development and urbanization have increased the accumulation of heavy metals in the soil， resulting in heavy metal pollution in the soil， and the pollution area has expanded year by year[6-8]. The National Soil Pollution Survey Bulletin， jointly issued by the Ministry of Land and Resources and the Ministry of Environmental Protection of the Peoples Republic of China on April 17， 2014，shows that the overall state of soil environment in China is not promising， soil pollution is serious in some regions and the cultivated soil environment quality is very low， where the exceeding standard rates of 8 kinds of heavy metals （Cd， Hg， As， Cu， Pb， Cr， Zn and Ni） are 7.0%，1.6%，2.7%， 2.1%， 1.5%， 1.1%， 0.9%， 4.8%， respectively. Moreover， 19.4% of the investigated sites in cultivated land exceed the maximum allowable heavy metal contents， and the proportions of slight， light， medium and heavy pollution are 13.7%， 2.8%， 1.8% and 1.1%，respectively. Therefore， it is the basis for agricultural ecological security to strengthen the investigation and evaluation of heavy metal pollution in cultivated land[9].The eastern coastal areas of China are dominated by plains， with good quality of cultivated land， flat and deep topsoil， and high levels of agricultural intensification. These areas have high level of urbanization and industrialization， thereby causing serious risk of agricultural land pollution. Therefore， in this paper， the distribution characteristics of soil heavy metals （Cr， Ni， Cu，Zn， As， Cd， Pb and Hg） in the topsoil （0-20 cm） of cultivated land were investigated with Donghai County， a typical agricultural county along the eastern coast of China， as an example，and the potential ecological risks were evaluated using the soil heavy metal accumulation index，with the aim to provide scientific bases and guidance for soil environmental quality assessment and land use planning in agricultural areas along the eastern coast of China.Materials and MethodsStudy areaLocated in the northeastern part of Jiangsu Province，China with the coordinates of 34°11′-34°44′N，118°23′-119°10′E， Donghai County borders the Yellow Sea on the east. With a humid monsoon climate， Donghai has an average annual temperature of 13.7 ℃ and an average precipitation of 912.3 mm. The county has 11 towns， 6 townships， 2 street offices， 2 stateowned farms， and 1 provincial farm. The total land area of the county is 200 981.02 hm;2， in which there is 155 642.97 hm;2 of agricultural land， accounting for 77.44% of the total land area; 36 770.72 hm;2 of construction land， accounting for 18.30% of the total land area; 8 583.33 hm;2 of unused land， accounting for 4.26% of the total land area. Among the agricultural land， the cultivated land area is 122 482.29 hm;2， accounting for 60.95% of the total land area. The soil of cultivated land is dominated by brown soil and Shajiang black soil， accounting for 46.38% and 39.52% of the cultivated land area of the county， respectively. Donghai County has a large ratio of agricultural land and is rich in cultivated land resources， making it suitable for planting rice， wheat， corn and other crops. It also has a long history of agriculture production， and longterm intensive cultivation has greatly improved the land limitation factors， so the land productivity is relatively high.Sample collection and analysisFrom the end of March to the beginning of April 2018， a total of 92 sampling points were set up in Donghai County. Considering the landform types and administrative divisions， 4-6 sampling points were arranged in each township. In order to avoid the influence of the surrounding environment， the sampling points were selected from the continuous cultivated land areas， which were located in the center of the cultivated land away from the rivers with the polygon area of greater than 6.67 hm;2 and a distance over 50 m from the roads and ditches （Fig.1）. The soil samples were collected using the 5spot method from the topsoil （0-20 cm） of each sampling point. For each sampling point， soil samples were collected from 5 spots on a diagonal of 10 m， and then the soil samples from the 5 spots were fully mixed. Then， 1 kg of soil was taken by the quartering method，which was then brought back to the laboratory in a plastic bag. In the meantime， the basic information of the sampling point was recorded， including the latitude and longitude， farming method， slope， and aspect. After removing the plant roots and rocks， the collected soil samples were airdried in the laboratory， and then the samples were ground and crushed， and screened through a 100mesh nylon sieve for determination of heavy metals in the soil. The contents of the 8 kinds of heavy metals， Cr， Ni， Cu， Zn， As， Cd， Pb and Hg， were determined accordingto the methods provided in the Guidance on Longterm Soil Monitoring in Natural Ecosystem （GB/T 32740-2016）.Data AnalysisThe classical statistical parameters such as mean， maximum， minimum， standard deviation and coefficient of variation were used to describe the overall characteristics of heavy metals in cultivated land in the study area. Among them， the standard deviation was the average distance of each data deviating from the average， which could reflect the dispersion degree of soil heavy metal data. The coefficient of variation （CV） could reflect the spatial variability of soil heavy metals，and CV≤10% indicated weak variability， CV of 10%-100% indicated moderate variability， and CV≥100% was intensity variability[10]. Classic statistical analysis was performed using PASW Statistics 18.0， and relevant statistical maps were drawn using SigmaPlot 12.5. The spatial distribution of heavy metals in soil was obtained by using the inverse distance weighted interpolation of ArcGIS 10.6.The potential ecological risks of heavy metals in soil were evaluated using the potential ecological risk index （PERI） proposed by Hakanson in 1980[11]. The calculation formula was as follows：C;if=Ci/Bi（1）E;ir=T;ir×C;if（2）RI=∑mi=1E;ir（3）Where， Ci is a measured concentration of metal i in the soil sample; Bi is the background value of same metal i in the soil， and in this study， the background values （total amount） of soil elements in Jiangsu Province were taken as the reference values[12]， namely， Cr of 75.6 mg/kg，Ni of 32.8 mg/kg， Cu of 23.4 mg/kg， Zn of 64.8 mg/kg， As of 9.4 mg/kg， Cd of 0.085 mg/kg，Pb of 22 mg/kg， and Hg of 0.025 ng/g）; T;ri is the toxicresponse factor of metal i according to the toxicity of heavy metals and the response of the environment， respectively Cr of 2， Ni of 5 ， Cu of 5， Zn of 1， As of 10， Cd of 30， Pb of 30 and Hg of 40[13]; C;if is the single contamination factor; E;ir is the monomial ecological risk factor of metal I; RI is potential ecological risk index，which characterizes the potential ecological risk degree of heavy metals in soil. The single contamination factor index and potential ecological risk index of Cr， Ni， Cu， Zn， As， Cd，Pb and Hg are classified according to the relevant literature[14-15].Results and AnalysisMean heavy metal content in topsoil of cultivated landThe statistical characteristics of heavy metal content in the topsoil soil of cultivated land in Donghai County were shown in Table 1. On the whole， the average contents of various heavy metals in cultivated land did not exceed the risk screening values set in the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land， but it is worth noting that in some of the sampling points， the contents of Cr， Ni， Cu and Cd exceeded the risk screening values，especially Cr had the most standard exceeding points， which reached 20， accounting for 24.74% of the total， while the standard exceeding points for Ni and Cu were 3， and 1 for Cd. The overstandard content of Cr may be caused by metal smelting， openair waste incineration， livestock wastes， and farmland irrigation[16-17]. At the same time， the average contents of heavy metals of Cr， Ni， As， Cd， Pb and Hg exceeded the soil background values of Jiangsu Province， and the average contents of Cd， Cr and Pb were more than 1.5 times of the soil background value of Jiangsu Province. In addition， the coefficients of variation of heavy metals at each sampling point were between 26.13% and 72.13%， which indicated moderate variability， and the variation from high to low was in the order of Hg > Ni > Cu > Cr > As > Pb > Cd > Zn. Among them， Hg had the largest coefficient of variation， indicating that it was most affected by exogenous factors.Distribution of heavy metals content in topsoil of cultivated landThe spatial distribution of various heavy metals in the topsoil of cultivated land in Donghai County was shown in Fig.2. The spatial distribution characteristics of the 8 kinds of heavy metals were significantly different. Specifically， the content of Cr was between 62.37 and 279.09 mg/kg，which was obviously higher in the western hilly area， and the high values were found in Linian Township and Shuangdian Town. The content of Ni was between 16.99 and 153.56 mg/kg， which was higher in the eastern plain area than the central gentle slope area， and the highest content was found at the junction of Linian Township and Shuangzuokou Township. The content of Cu was between 11.21 and 56.47 mg/kg， and the highest content was located in Taolin Town and Shilianghe Town. The content of Zn was between 33.93 and 99.55 mg/kg， which was higher in the east and lower in the middle and west， and highest value was found in Pingming Town and Zhangwan Town. The content of As was between 5.33 and 27.06 mg/kg， and the distribution characteristics were consistent with the spatial trend of elevation， showing a trend of low in the west and high in the east. The content of Cd was between 0.083 and 0.35 mg/kg， and the highest content was located in Taolin Town. The content of Pb was between 19.64 and 78.78 mg/kg， and the areas with relatively higher content were mainly distributed in Taolin Town in the west and Niushan Town and Baitabu Town in the central part. The content of Hg was between 7.90 and 159.33 ng/g， and the content of Hg in the eastern plain was higher， mainly concentrated in Pingming Town and Shilianghe Town.Assessment of potential ecological risk of heavy metalsThe average single contamination factors （Ci） of the 8 kinds of heavy metals in cultivated land in Donghai County were calculated from the soil background values of Jiangsu Province as Cd of 1.89 > Cr of 1.65 > Pb of 1.53 > As of 1.19 > Hg of 1.14 > Ni of 1.12 > Cu of 0.97 > Zn of 0.88.According to PERI classification[14-15]， the heavy metals such as Cd， Cr， As， Hg and Ni in cultivated land were in the moderate pollution levels （1-3）， and Cu and Zn were in the light pollution levels （<1）.The average monomial ecological risk factor （E;ri） of the soil heavy metals showed that the ecological risk factors of As （11.88）， Ni （5.58）， Cu （4.83）， Cr （3.30） and Zn（0.88） were all smaller than 30， indicating light potential risk， the ecological risk factors of Cd （56.69）， Pb （45.87） and Hg （45.69） were in the range of 30-60， indicating that the potential ecological risk was moderate， but it was worth noting that the ecological risk factor of Cd was close to the upper limit of the moderate risk span.The potential ecological risk index （RI） of heavy metals in the surface of cultivated land in Donghai County was between 107.39% and 383.76%， and the regional average was 174.73，indicating that the overall potential ecological risk level of heavy metals was moderate （110-220）in Donghai County. The spatial distribution of potential ecological risk index showed a gradual increasing trend from west to east. The potential ecological risk index of the plain area in the east was higher than that in the central gentle slope area and the western hill area. The reasons may be related to soil type， arable land elevation， proximity to urban areas， and agricultural production levels （use of agricultural inputs such as chemical fertilizers， pesticides， organic fertilizers， and sludge）[18-20]. In addition， the ecological risks were high in the regions with high urbanization levels like Niushan Town， Taolin Town， Baitabu Town， Pingming Town， Shilianghe Town and Shilianghe Town， which were in the highlevel risk area.Conclusion（1） The average content of heavy metals in the cultivated soil of Donghai County was not over the risk screening values set in the Environmental Quality Standard for Soils. However， it was worth noting that in some of the sampling points， the content of Cr exceeded the risk screening value， and the standard exceeding points accounted for 24.74% of the total. In addition， the average content of Cr， Ni， As， Cd， Pb and Hg exceeded the soil background values of Jiangsu Province， and values for Cd， Cr and Pb were more than 1.5 times of the soil background value of Jiangsu Province.（2） The heavy metals were at the medium integrated potential ecological risk level， and the potential ecological risk indices were high in the east and low in the west， and distributed in interlaced island shape. The potential ecological risk indices of the plains in the east were higher than those of the central gentle slope area and the western hillock area. The potential ecological risk was at a high level in Niushan Town which was situated the county center and in some regions with high urbanization levels.References[1] CHEN HM， ZHENG CR， TU C， et al. Heavy Metal Pollution in Soils in China： Status and Countermeasures[J]. Ambio， 1999， 28（2）：130-134.[2] RAGHUNATH R， TRIPATHI RM， KUMAR AV， et al. Assessment of Pb， Cd，Cu， and Zn exposures of 6 to 10yearold children in Mumbai[J]. Environmental Research， 1999，80（3）：215.[3] JIAO WT， CHEN WP， CHANG AC， et al. Environmental risks of trace elements associated with longterm phosphate fertilizers applications： a review[J]. Environmental Pollution，2012， 168（1）：44-53.[4] SINGH J， LEE BK. Reduction of environmental availability and ecological risk of heavy metals in automobile shredder residues[J]. Ecological Engineering， 2015， 81： 76-81.[5] LIU JL， WU H， FENG JX， et al. Heavy metal contamination and ecological risk assessments in the sediments and zoobenthos of selected mangrove ecosystems， South China[J]. Catena， 2014， 119： 136-142.[6] YANG Y， JIN Q， FANG JM， et al. Spatial distribution， ecological risk assessment，and potential sources of heavy metal（loid）s in surface sediments from the Huai River within the Bengbu section， China[J]. Environmental Science and Pollution Research， 2017， 24（12）：11360-11370.[7] ISLAM MS， AHMED MK， RAKNUZZAMAN M， et al. Heavy metals in the industrial sludge and their ecological risk： A case study for a developing country[J]. Journal of Geochemical Exploration， 2017， 172： 41-49.[8] KE X， GUI S， HUANG H， et al. Ecological risk assessment and source identification for heavy metals in surface sediment from the Liaohe River protected area， China[J]. Chemosphere，2017， 175： 473-481.[9] TIAN K， HUANG B， XING Z， et al. Geochemical baseline establishment and ecological risk evaluation of heavy metals in greenhouse soils from Dongtai， China[J]. Ecological indicators， 2017， 72： 510-520.[10] WANG HM， XIE YZ， WANG K. Spatial heterogeneity of soil moisture in different artificial grasslands with finer scales[J]. Acta Agrestia Sinica， 2013， 21（6）：1052-1058.[11] HAKANSON L. An ecological risk index for aquatic pollution control： a sedimentological approach[J]. Water Research， 1980， 14（8）：975-1001.[12] GB 15618—1995 Environmental Quality Standard for Soil. Beijing： Standards Press of China，1997.[13] XU ZQ， NI SJ， TAO XG， et al. Calculation of Heavy Metals Toxicity Coefficient in the Evaluation of Potential Ecological Risk Index[J].Environmental Science & Technology， 2008，31（2）：112-115.[14] LI QL， WU Q， GAO JB， et al. Distribution of heavy metals in topsoils affected by land use patterns at a small watershed scale： a case study in the Bantou Reservoir watershed in Xiamen，China[J]. Acta Ecologica Sinica，2015，35（16）： 5486-5494.[15] JU TN， WU X， SHI HD， et al. Heavy metal pollution and Ecological Risk assessment of arable land soil in Haigou small watershed[J]. Journal of Environmental Engineering Technology，2018， 8（5）： 556-562.[16] LU SJ， WANG YY， TENG YG， et al. Heavy metal pollution and ecological risk assessment of the paddy soils near a zinclead mining area in Hunan[J]. Environmental monitoring and assessment， 2015， 187（10）： 627.[17] BAI JH， CUI BS， CHEN B， et al. Spatial distribution and ecological risk assessment of heavy metals in surface sediments from a typical plateau lake wetland， China[J]. Ecological Modelling， 2011， 222（2）： 301-306.[18] SUN H， DU Y， SONG YB， et al. Distribution and Evaluation of Contamination of Heavy Metals in Selected Farmland Soils in Donghai County of Jiangsu Province[J]. Journal of AgroEnvironment Science， 2006.[19] BARKETT MO， AKUN E. Heavy metal contents of contaminated soils and ecological risk assessment in abandoned copper mine harbor in Yedidalga， Northern Cyprus[J]. Environmental Earth Sciences， 2018， 77（10）： 378.[20] DING XG， YE SY， YUAN HM， et al. Spatial distribution and ecological risk assessment of heavy metals in coastal surface sediments in the Hebei Province offshore area， Bohai Sea， China[J]. 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甘薯及其野生近缘种的基因组测序研究进展
第３８卷第２期２０２０年５月江苏师范大学学报（自然科学版）ＪｏｕｒｎａｌｏｆＪｉａｎｇｓｕＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ（ＮａｔｕｒａｌＳｃｉｅｎｃｅＥｄｉｔｉｏｎ）Ｖｏｌ．３８，Ｎｏ．２Ｍａｙ，２０２０ 收稿日期：２０２０ ０３ ２０基金项目：江苏省自然科学基金项目（ＢＫ２０１９０９９６），江苏师范大学博士学位教师科研支持项目（１８ＸＬＲＸ０３３），江苏高校优势学科建设工程资助项目（ＰＡＰＤ），现代农业产业技术体系建设专项资金（ＣＡＲＳ １０ Ｂ３）作者简介：勾晓婉，女，讲师，博士，主要从事植物细胞遗传学与基因组学研究．通信作者：李宗芸，女，教授，博士生导师，主要从事植物遗传学研究，Ｅ ｍａｉｌ：ｚｏｎｇｙｕｎｌｉ＠ｊｓｎｕ．ｅｄｕ．ｃｎ．文章编号：２０９５ ４２９８（２０２０）０２ ００５２ ０３甘薯及其野生近缘种的基因组测序研究进展勾晓婉，侯文倩，平艳飞，韩永华，李宗芸（江苏师范大学生命科学学院，江苏徐州２２１１１６）摘要：甘薯作为重要的粮食与经济作物，拥有复杂且庞大的基因组，因此，其基因组测序、拼接等相关研究一直进展缓慢．综述了近年来栽培甘薯及其野生近缘种相关的基因组测序研究进展，为有效利用基因组学分析手段对甘薯进行遗传育种、性状改良等方面的研究提供参考．关键词：番薯属；甘薯；野生近缘种；基因组测序中图分类号：Ｑ３，Ｓ５３１ 文献标识码：Ａ 犱狅犻：１０．３９６９／ｊ．ｉｓｓｎ．２０９５ ４２９８．２０２０．０２．０１１犚犲狊犲犪狉犮犺犪犱狏犪狀犮犲犻狀犵犲狀狅犿犻犮狊犲狇狌狀犮犻狀犵狅犳狊狑犲犲狋狆狅狋犪狋狅犪狀犱犻狋狊狑犻犾犱狉犲犾犪狋犻狏犲狊ＧｏｕＸｉａｏｗａｎ，ＨｏｕＷｅｎｑｉａｎ，ＰｉｎｇＹａｎｆｅｉ，ＨａｎＹｏｎｇｈｕａ，ＬｉＺｏｎｇｙｕｎ（ＳｃｈｏｏｌｏｆＬｉｆｅＳｃｉｅｎｃｅ，ＪｉａｎｇｓｕＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ，Ｘｕｚｈｏｕ２２１１１６，Ｊｉａｎｇｓｕ，Ｃｈｉｎａ）犃犫狊狋狉犪犮狋：Ｓｗｅｅｔｐｏｔａｔｏｉｓａｎｉｍｐｏｒｔａｎｔｆｏｏｄａｎｄｃａｓｈｃｒｏｐ，ｉｔｈａｓａｈｕｇｅａｎｄｃｏｍｐｌｅｘｇｅｎｏｍｅ．Ｔｈｅｒｅｆｏｒｅ，ｉｔｓｇｅｎｏｍ ｉｃｓｅｑｕｅｎｃｉｎｇ，ｓｐｌｉｃｉｎｇａｎｄｏｔｈｅｒｒｅｌａｔｅｄｓｔｕｄｉｅｓｈａｖｅｂｅｅｎｐｒｏｇｒｅｓｓｉｎｇｓｌｏｗｌｙ．Ｉｎｔｈｉｓｐａｐｅｒ，ｔｈｅａｄｖａｎｃｅｉｎｇｅｎｏｍｉｃｓｅｑｕｅｎｃｉｎｇｏｆｃｕｌｔｉｖａｔｅｄｓｗｅｅｔｐｏｔａｔｏａｎｄｉｔｓｗｉｌｄｒｅｌａｔｉｖｅｓｐｅｃｉｅｓａｒｅｒｅｖｉｅｗｅｄ，ｉｔｃａｎｂｅｐｒｏｖｉｄｅｄａｒｅｆｅｒｅｎｃｅｆｏｒｔｈｅｒｅｓｅａｒｃｈｏｎｇｅｎｅｔｉｃｂｒｅｅｄｉｎｇａｎｄｃｈａｒａｃｔｅｒｉｍｐｒｏｖｅｍｅｎｔｏｆｓｗｅｅｔｐｏｔａｔｏｂｙｕｓｉｎｇｇｅｎｏｍｉｃａｎａｌｙｓｉｓ．犓犲狔狑狅狉犱狊：犐狆狅犿狅犲犪；ｓｗｅｅｔｐｏｔａｔｏ；ｗｉｌｄｒｅｌａｔｉｖｅｓｏｆｓｗｅｅｔｐｏｔａｔｏ；ｇｅｎｏｍｉｃｓｅｑｕｅｎｃｉｎｇ 基因组学是由美国遗传学家ＴｈｏｍａｓＨ．Ｒｏｄ ｅｒｉｃｋ于１９８６年提出，用于研究生物基因组的结构与功能的一门新兴学科［１］．基因组测序技术也在近４０年得到飞速发展，从１９７７年以Ｓａｎｇｅｒ发明的“双脱氧链终止法”［２］和Ｍａｘａｍ Ｇｉｌｂｅｒｔ的“化学降解法”［３］为标志的第１代测序技术的兴起，到Ｒｏｃｈｅ、Ｉｌｌｕｍｉｎａ和ＡＢＩ３大测序公司引领的第２代测序，再到现今的纳米孔单分子３代测序等［４］，实现了基因组测序水平从低通量到高通量、高成本向低成本的转变，同时也大大提升了ＤＮＡ测序的精确度，为各物种的基因组测序提供了技术支持．甘薯［犐狆狅犿狅犲犪犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．］，又称番薯、红薯、地瓜、山芋等，属于旋花科（Ｃｏｎｖｏｌｖｕｌａｃｅａｅ）番薯属（犐狆狅犿狅犲犪）植物，是重要的粮食、经济和能源作物．甘薯块根中富含多种营养物质，如花青素、类胡萝卜素、多种维生素、膳食纤维以及钙、铁、硒等矿物质［５］．除食用价值外，甘薯还可用于制作淀粉、酒精、天然色素等，茎叶可制作饲料．另外，甘薯起源于美洲大陆的热带和亚热带地区［６］，其生存环境决定了它具有耐高温、抗旱等优良性状［７］，为在全世界范围的种植奠定了基础．栽培甘薯是六倍体物种（２狀＝６狓＝９０），基因组庞大，且具有无性繁殖、自交不亲和的特性，使得甘薯的遗传组成等基础研究进展缓慢，落后于其他主要作物．然而，随着高通量测序和生物信息学技术的迅猛发展，甘薯基因组学和生物信息学的研究工作如火如荼，进展迅速［８－１０］．本文梳理了甘薯及其近缘野生种的基因组测序发展历程，为更好地利用日趋精细的基因组图谱信息，理清甘薯组的起源进化关系，挖掘抗病虫害等重要基因，以及甘薯育种及品质改良提供理论基础．１ 甘薯野生近缘种基因组研究进展在测序过程中，因多倍体植物部分同源染色体间的序列相似性，序列拼接成为难点．因此，科学家常优先完成二倍体祖先物种的测序以作为多倍体物种的参考基因组．番薯属的研究策略亦是如此．２０１０年，日本学者利用二倍体三浅裂野牵牛（犐狆狅犿狅犲犪狋狉犻犳犻犱犪２狀＝２狓＝３０）的０４３１ １与Ｍｘ２３ ４品系杂交获得的Ｆ１群体构建扩增片段长度多态性（ＡＦＬＰ）连锁图谱．其中，０４３１ １品系获得了１７个连锁群，Ｍｘ２３ ４品系获得了１５个连锁群［１１］，此连锁图谱被认为是构建甘薯参考基因组的第１步骤．至２０１５年，此课题组对前述２个犐．狋狉犻犳犻犱犪品系进行从头合成全基因组测序［１２］，自交系Ｍｘ２３Ｈｍ（由Ｍｘ２３ ４自交至Ｓ１１代）成功装配５１３Ｍｂ的基因组，推测包含６２４０７个基因；高度杂合系０４３１ １成功装配７１２Ｍｂ的基因组，约包含１０９４４９个基因．数据对比发现，两组材料之间存在着大量的单核苷酸多态性（ＳＮＰ）和拷贝数变异［１２］．这些基因组数据为犐．狋狉犻犳犻犱犪及番薯属其他物种的研究奠定了基础．２０１６年，日本科学家利用２代与３代测序相结合的手段，破解了牵牛花（犐狆狅犿狅犲犪狀犻犾，２狀＝２狓＝３０）的基因组图谱［１３］，共拼接出大小为７５０Ｍｂ的基因组，预测其包含４３７８３个基因，ｃｏｎｔｉｇＮ５０长度为１．８７Ｍｂ，ｓｃａｆｆｏｌｄＮ５０长度为２．８８Ｍｂ，覆盖总基因组的９８％，并将所有的ｓｃａｆｆｏｌｄ都挂载到了１５条假定染色体上．利用组装好的基因组检测Ｔｐｎ１家族的转座子，发现它是牵牛花突变的主要诱变剂，并且与矮杆基因犆犗犖犜犚犃犆犜犈犇作用相关［１３］．牵牛花的基因组序列为番薯属第１个装配到染色体水平上的基因组草图．２０１８年，由美国、中国、澳大利亚、秘鲁、肯尼亚、乌干达６个国家的１６支科研团队通力合作，共同绘制出犐．狋狉犻犳犻犱犪和犐．狋狉犻犾狅犫犪２个甘薯二倍体野生种的高质量基因组图谱，为六倍体甘薯改良提供了参考［１４］．装配出的犐．狋狉犻犳犻犱犪基因组大小为４６２Ｍｂ，ｓｃａｆｆｏｌｄＮ５０长度约１．２Ｍｂ，包含约３２３０１个蛋白编码基因；犐．狋狉犻犾狅犫犪基因组大小为４５７．８Ｍｂ，ｓｃａｆｆｏｌｄＮ５０长度约６．９Ｍｂ，包含约３１４２３个蛋白编码基因．通过基因组序列的系统发生关系对比，证明犐．狋狉犻犳犻犱犪与栽培甘薯的亲缘关系更近［１４］．２０１９年，霍恺森等利用流式细胞术和２代测序技术，对马鞍藤（犐狆狅犿狅犲犪狆犲狊 犮犪狆狉犪犲）全基因组大小进行了测定和评估．流式细胞术估测马鞍藤的基因组大小为（１０１２．７０４±１７．３７）Ｍｂ，测序数据拼接草图估测基因组大小为１０４１．６５Ｍｂ，且重复序列占比高达７４．５２％［１５］，此结果为马鞍藤基因组的深度测序和耐盐基因在栽培甘薯中的应用打下了基础．同年，同一课题组对甘薯近缘野生种犐．犾犻狋狋狅狉犪犾犻狊也进行了全基因组评估分析，数据经过滤拼接之后，预估其基因组大小为６７６．２７Ｍｂ，重复序列比例达６０．９８％．此研究首次报道犐．犾犻狋狋狅狉犪犾犻狊基因组特征信息，为进一步全基因组深度测序提供了参考［１６］．２ 栽培甘薯基因组研究进展早在１９９４年，Ｏｚｉａｓ Ａｋｉｎｓ等利用流式细胞术对番薯属２４个物种的５３个品系进行ＤＮＡ含量评估，证明该属物种的倍性水平与ＤＮＡ含量显著相关，且测定栽培甘薯基因组的ＤＮＡ含量为４．８～５．３ｐｇ／２Ｃ［１７］．２０１８年，Ｓｒｉｓｕｗａｎ等重新分析番薯属物种的ＤＮＡ含量，与前人报道略有不同，１０个六倍体栽培甘薯样本的ＤＮＡ含量平均为３．１２～３．２９ｐｇ／２Ｃ．另外，通过扫描电镜对花粉粒的尺寸分析也证明花粉粒的大小会随着倍性增加而增大［１８］．２００３年，Ｋｒｉｅｇｎｅｒ等利用ＡＦＬＰ技术对Ｔａｎ ｚａｎｉａ和Ｂｉｋｉｌａｍａｌｉｙａ２个甘薯品种进行遗传连锁图绘制，结合分子标记，获得连锁图谱长度分别为３６５５．６ｃＭ和３０１１．５ｃＭ［１９］．２０１６年，Ｓｉ等第１次构建了甘薯的ＢＡＣ（ｂａｃｔｅｒｉａｌａｒｔｉｆｉｃｉａｌｃｈｒｏｍｏｓｏｍｅ）文库，此文库包含２４０３８４个克隆，平均插入长度为１０１ｋｂ，文库数据量是甘薯全基因组大小的７．９～１０．８倍．从文库中随机选择８３１０个克隆进行双端测序，产生１１５４２条高质量ＢＥＳｓ（ＢＡＣ ｅｎｄｓｅｑｕｅｎｃｅｓ）序列，累计测序长度达７５９５２６１ｂｐ．对ＢＥＳｓ序列分析显示，１２．１７％为甘薯基因组内已知的重复序列，１８．３１％为其特有的重复ＤＮＡ，仅有１０．００％预测为蛋白编码区［２０］．ＢＡＣ文库为后续高分辨率的基因组组装提供了强大支援．２０１７年，中德科学家合作，对栽培甘薯“泰中６号”进行测序，利用Ｉｌｌｕｍｉｎａ测序平台，采用单倍型分析手段，成功绘制了六倍体甘薯的基因组精细图谱［２１］，其总基因组大小约为４．４Ｇｂ，单套染色体大小约为８３６Ｍｂ，ｓｃａｆｆｏｌｄＮ５０约为２０１ｋｂ．以犐．狀犻犾的基因组序列作为参考，通过共线性分析，将约７５．７％的改良版单倍型拼接区段数据锚定到１５条假定染色体上．另外，通过构建同源染色体的系统发生树，推测现今栽培甘薯形成过程经历２次全基因组加倍事件：第１次加倍事件发生在约８０万年前，形成了甘薯的四倍体祖先；第２次加倍事件发生在约５０万年前，二倍体祖先与四倍体祖先经过杂交和多倍化，成为六倍体甘薯（Ｂ１Ｂ１Ｂ２Ｂ２Ｂ２Ｂ２）［２１］．２０１９年，Ｄｉｎｇ等［２２］采用２、３代测序技术相结合的方法，对栽培品种徐薯１８和野生近缘种犐．狋狉犻犳犻犱犪进行多个植物组织（如幼嫩叶片、成熟叶片、芽、茎、纤维根等）的全长转录组测序，结果显示，２组材料中的开放阅读框数目高达１０４５１０和９４１７４个，长链非编码ＲＮＡ有４１７和５３１条，同时还伴随高频率的可变剪接时间的发生．这项研究提供的甘薯及其野生种的全长转录本资源，促进了甘薯的结构、功能和比较基３５第２期勾晓婉，等：甘薯及其野生近缘种的基因组测序研究进展 因组学的发展．２０２０年，Ｆｅｎｇ等［２３］利用ＲＡＤ ｓｅｑ技术分析８１个甘薯品系，评估甘薯的遗传结构多样性．通过＞１２８Ｇｂ的大数据，共鉴定５５６２２个限制性位点标签，包含９０７０１０个ＳＮＰ．利用全基因组ＳＮＰ分型数据，基于遗传相似性，将８１个品系分为５大类，这种分类方式有助于育种专家寻找适合用于杂交的品系，以提高待育品种的品质或抗性．另外，通过对此数据分析，还建立了一套ＳＳＲ标记系统，为育种过程提供更加丰富的辅助标记［２３］．３ 展望随着测序技术的不断升级优化以及生物信息学分析手段的迅猛发展，越来越多的物种基因组被破译．尽管甘薯基因组十分复杂，但参考序列也在循序更新，不断完善，为以后的精细基因功能研究奠定了基础．通过不同品种甘薯的基因组比较，以及对野生物种基因组资源的开发，可以获取到相关重要农艺性状的基因或位点信息，从而实现分子、序列水平的定点育种改良．另外，甘薯起源问题也一直困扰着科学家们，现有望利用ＤＮＡ水平的数据比对，理清甘薯的起源与进化过程．现今甘薯种植面临多种病虫害的侵蚀，如根腐病、蔓割病、黑斑病、茎线虫病等，以及生长环境的恶劣影响，例如土地的盐碱化、高温天气延长、干旱地区扩张等，大大降低了甘薯的产量．甘薯基因组信息的完善，可以使科学家从更精细的层面去探寻抗性基因，实现存优去劣，使甘薯自身具有较高的抵抗不利环境的能力，从而减少外界药物或肥料的施加，提高生产安全性，减轻土地负担，实现良性发展．参考文献：［１］ 李伟，印莉萍．基因组学相关概念及其研究进展［Ｊ］．生物学通报，２０００，３５（１１）：１．［２］ ＳａｎｇｅｒＦ，ＮｉｃｋｌｅｎＳ，ＣｏｕｌｓｏｎＡＲ．ＤＮＡｓｅｑｕｅｎｃｉｎｇｗｉｔｈｃｈａｉｎ ｔｅｒｍｉｎａｔｉｎｇｉｎｈｉｂｉｔｏｒｓ［Ｊ］．ＰＮＡＳ，１９７７，７４（１２）：５４６３．［３］ ＭａｘａｍＡＭ，ＧｉｌｂｅｒｔＷ．ＡｎｅｗｍｅｔｈｏｄｆｏｒｓｅｑｕｅｎｃｉｎｇＤＮＡ［Ｊ］．ＰＮＡＳ，１９７７，７４（２）：５６０．［４］ 孙海汐，王秀杰．ＤＮＡ测序技术发展及其展望［Ｊ］．科研信息化技术与应用，２００９（３）：１９．［５］ 张立明，王庆美，王荫墀．甘薯的主要营养成分和保健作用［Ｊ］．杂粮作物，２００３，２３（３）：１６２．［６］ 小林仁，邓纯宝．甘薯的起源与分化Ⅰ．甘薯的原产地和品种分化［Ｊ］．国外农学杂粮作物，１９８３（１）：４３．［７］ ＭａｂｈａｕｄｈｉＴ，ＭｏｄｉＡＴ，ＭｏｔｓａＮＭ．Ｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊Ｌ．）ａｓａｄｒｏｕｇｈｔｔｏｌｅｒａｎｔａｎｄｆｏｏｄｓｅｃｕｒｉｔｙｃｒｏｐ［Ｊ］．ＳＡｆｒＪＳｃｉ，２０１５，１１１（１１／１２）：１．［８］ ＩｓｏｂｅＳ，ＳｈｉｒａｓａｗａＫ，ＨｉｒａｋａｗａＨ．Ｃｈａｌｌｅｎｇｅｓｔｏｇｅ ｎｏｍｅｓｅｑｕｅｎｃｅｄｉｓｓｅｃｔｉｏｎｉｎｓｗｅｅｔｐｏｔａｔｏ［Ｊ］．ＢｒｅｅｄＳｃｉ，２０１７，６７（１）：３５．［９］ 杨俊，范维娟，王红霞，等．番薯属植物基因组测序最新进展［Ｊ］．植物生理学报，２０１７，５３（５）：７６８．［１０］ ＩｓｏｂｅＳ，ＳｈｉｒａｓａｗａＫ，ＨｉｒａｋａｗａＨ．Ｃｕｒｒｅｎｔｓｔａｔｕｓｉｎｗｈｏｌｅｇｅｎｏｍｅｓｅｑｕｅｎｃｉｎｇａｎｄａｎａｌｙｓｉｓｏｆ犐狆狅犿狅犲犪ｓｐｐ．［Ｊ］．ＰｌａｎｔＣｅｌｌＲｅｐ，２０１９，３８（１１）：１３６５．［１１］ ＮａｋａｙａｍａＨ，ＴａｎａｋａＭ，ＴａｋａｈａｔａＹ．ＡｎＡＦＬＰ ｂａｓｅｄｇｅｎｅｔｉｃｌｉｎｋａｇｅｍａｐｏｆ犐狆狅犿狅犲犪狋狉犻犳犻犱犪（Ｈ．Ｂ．Ｋ．）Ｇ．Ｄｏｎ．，ａｄｉｐｌｏｉｄｒｅｌａｔｉｖｅｏｆｓｗｅｅｔｐｏｔａｔｏ，犐．犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．［Ｊ］．ＴｒｏｐＡｇｒｉｃＤｅｖ，２０１０，５４（１）：９．［１２］ ＨｉｒａｋａｗａＨ，ＯｋａｄａＹ，ＴａｂｕｃｈｉＨ，ｅｔａｌ．Ｓｕｒｖｅｙｏｆｇｅ ｎｏｍｅｓｅｑｕｅｎｃｅｓｉｎａｗｉｌｄｓｗｅｅｔｐｏｔａｔｏ，犐狆狅犿狅犲犪狋狉犻犳犻犱犪（Ｈ．Ｂ．Ｋ．）Ｇ．Ｄｏｎ［Ｊ］．ＤＮＡＲｅｓ，２０１５，２２（２）：１７１．［１３］ ＨｏｓｈｉｎｏＡ，ＪａｙａｋｕｍａｒＶ，ＮｉｔａｓａｋａＥ，ｅｔａｌ．ＧｅｎｏｍｅｓｅｑｕｅｎｃｅａｎｄａｎａｌｙｓｉｓｏｆｔｈｅＪａｐａｎｅｓｅｍｏｒｎｉｎｇｇｌｏｒｙ犐狆狅犿狅犲犪狀犻犾［Ｊ］．ＮａｔＣｏｍｍ，２０１６，７（１）：１３２９５．［１４］ ＷｕＳ，ＬａｕＫＨ，ＣａｏＱＨ，ｅｔａｌ．Ｇｅｎｏｍｅｓｅｑｕｅｎｃｅｓｏｆｔｗｏｄｉｐｌｏｉｄｗｉｌｄｒｅｌａｔｉｖｅｓｏｆｃｕｌｔｉｖａｔｅｄｓｗｅｅｔｐｏｔａｔｏｒｅｖｅａｌｔａｒｇｅｔｓｆｏｒｇｅｎｅｔｉｃｉｍｐｒｏｖｅｍｅｎｔ［Ｊ］．ＮａｔＣｏｍｍ，２０１８，９（１）：４５８０．［１５］ 霍恺森，赵冬兰，陈艳丽，等．甘薯属耐盐植物马鞍藤基因组大小及特征分析［Ｊ］．植物遗传资源学报，２０１９，２０（３）：７２８．［１６］ 霍恺森，曹清河，王珧，等．甘薯近缘野生种犐狆狅犿狅犲犪犾犻狋狋狅狉犪犾犻狊全基因组Ｓｕｒｖｅｙ分析［Ｊ］．热带作物学报，２０１９，４０（１０）：２００１．［１７］ Ｏｚｉａｓ ＡｋｉｎｓＰ，ＪａｒｒｅｔＲＬ．ＮｕｃｌｅａｒＤＮＡｃｏｎｔｅｎｔａｎｄｐｌｏｉｄｙｌｅｖｅｌｓｉｎｔｈｅｇｅｎｕｓ犐狆狅犿狅犲犪［Ｊ］．ＪＡｍＳｏｃｆｏｒＨｏｒｔＳｃｉ，１９９４，１１９（１）：１１０．［１８］ ＳｒｉｓｕｗａｎＳ，ＳｉｈａｃｈａｋｒＤ，ＭａｒｔｉｎＪ，ｅｔａｌ．ＣｈａｎｇｅｉｎＮｕｃｌｅａｒＤＮＡｃｏｎｔｅｎｔａｎｄｐｏｌｌｅｎｓｉｚｅｗｉｔｈｐｏｌｙｐｌｏｉｄｉｓａｔｉｏｎｉｎｔｈｅｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊，Ｃｏｎｖｏｌｖｕｌａｃｅａｅ）ｃｏｍｐｌｅｘ［Ｊ］．ＰｌａｎｔＢｉｏｌ，２０１９，２１（２）：２３７．［１９］ ＫｒｉｅｇｎｅｒＡ，ＣｅｒｖａｎｔｅｓＪ，ＢｕｒｇＫ，ｅｔａｌ．Ａｇｅｎｅｔｉｃｌｉｎｋａｇｅｍａｐｏｆｓｗｅｅｔｐｏｔａｔｏ［犐狆狅犿狅犲犪犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．］ｂａｓｅｄｏｎＡＦＬＰｍａｒｋｅｒｓ［Ｊ］．ＭｏｌＢｒｅｅｄ，２００３，１１（３）：１６９．［２０］ ＳｉＺＺ，ＤｕＢ，ＨｕｏＪＸ，ｅｔａｌ．Ａｇｅｎｏｍｅ ｗｉｄｅＢＡＣ ｅｎｄｓｅｑｕｅｎｃｅｓｕｒｖｅｙｐｒｏｖｉｄｅｓｆｉｒｓｔｉｎｓｉｇｈｔｓｉｎｔｏｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊（Ｌ．）Ｌａｍ．）ｇｅｎｏｍｅｃｏｍｐｏｓｉｔｉｏｎ［Ｊ］．ＢＭＣＧｅｎｏｍｉｃｓ，２０１６，１７（１）：９４５．［２１］ ＹａｎｇＪ，ＭｏｅｉｎｚａｄｅｈＭＨ，ＫｕｈｌＨ，ｅｔａｌ．Ｈａｐｌｏｔｙｐｅ ｒｅ ｓｏｌｖｅｄｓｗｅｅｔｐｏｔａｔｏｇｅｎｏｍｅｔｒａｃｅｓｂａｃｋｉｔｓｈｅｘａｐｌｏｉｄｉｚａｔｉｏｎｈｉｓｔｏｒｙ［Ｊ］．ＮａｔＰｌａｎｔｓ，２０１７，３（９）：６９６．［２２］ ＤｉｎｇＮ，ＣｕｉＨ，ＭｉａｏＹ，ｅｔａｌ．Ｓｉｎｇｌｅ ｍｏｌｅｃｕｌｅｒｅａｌ ｔｉｍｅｓｅｑｕｅｎｃｉｎｇｉｄｅｎｔｉｆｉｅｓｍａｓｓｉｖｅｆｕｌｌ ｌｅｎｇｔｈｃＤＮＡｓａｎｄａｌｔｅｒｎａｔｉｖｅ ｓｐｌｉｃｉｎｇｅｖｅｎｔｓｔｈａｔｆａｃｉｌｉｔａｔｅｃｏｍｐａｒａｔｉｖｅａｎｄｆｕｎｃｔｉｏｎａｌｇｅｎｏｍｉｃｓｓｔｕｄｙｉｎｔｈｅｈｅｘａｐｌｏｉｄｃｒｏｐｓｗｅｅｔｐｏｔａｔｏ［Ｊ］．ＰｅｅｒＪ，２０１９（７）：ｅ７９３３．［２３］ ＦｅｎｇＪＹ，ＺｈａｏＳ，ＬｉＭ，ｅｔａｌ．Ｇｅｎｏｍｅ ｗｉｄｅｇｅｎｅｔｉｃｄｉｖｅｒｓｉｔｙｄｅｔｅｃｔｉｏｎａｎｄｐｏｐｕｌａｔｉｏｎｓｔｒｕｃｔｕｒｅａｎａｌｙｓｉｓｉｎｓｗｅｅｔｐｏｔａｔｏ（犐狆狅犿狅犲犪犫犪狋犪狋犪狊）ｕｓｉｎｇＲＡＤ ｓｅｑ［Ｊ］．Ｇｅｎｏｍｉｃｓ，２０２０，１１２（２）：１９７８．［责任编辑：史成娣］４５ 江苏师范大学学报（自然科学版）第３８卷 。
北方湖库沉积物重金属区域特征及生态风险评价
中国环境科学 2020,40(11)：4927~4935 China Environmental Science 北方湖库沉积物重金属区域特征及生态风险评价李捷1,2,3,宋鹏2,李慧1,2,程云轩1,焦立新1,3*,李国栋1(1.中国环境科学研究院,湖泊水污染治理与生态修复技术国家工程实验室,北京 100012；2.河南科技大学农学院,河南洛阳 471000；3.中国环境科学研究院,国家环境保护饮用水水源地保护重点实验室,国家环境保护湖泊污染控制重点实验室,北京 100012)摘要：以白洋淀、衡水湖、于桥水库、松花湖、大伙房水库和小兴凯湖沉积作为研究对象,通过对北方六湖库沉积物中Cu、Zn、Pb、Cr、Ni等重金属元素进行分析,并与国内外其他水域重金属污染情况进行多因素比较,探讨了六湖库主要重金属污染源的差异性,区域分布特征以及与国内外其他水域污染的相似性和区别.结果表明,六湖库沉积物重金属污染处于中等偏下水平.六湖库之间主要重金属污染源存在差别.沉积物重金属含量未出现明显上升的趋势.其中Zn、Pb存在富集现象,但Pb含量与历史数据相比出现下降,Zn的含量与其他地区相比整体偏高.大伙房水库沉积物重金属污染较重,Cu、Zn、Pb、Cr、Ni含量平均值分别为56.28,142.3,17.44,97.9,44.44mg/kg.小兴凯湖沉积物重金属含量最低,Cu、Zn、Pb、Cr、Ni含量平均值分别为2.41,63.90,13.37,56.36,26.09mg/kg.六湖库综合风险评价结果为大伙房水库>于桥水库>白洋淀>衡水湖>松花湖>小兴凯湖,重金属整体潜在生态风险指数为低.关键词：湖库；沉积物；重金属；空间分布特征；生态风险；北方中图分类号：X131 文献标识码：A 文章编号：1000-6923(2020)11-4927-09Heavy metal regional characteristics and potential ecological risk assessment of lakes and reservoirs in North China. LI Jie1,2,3, SONG Peng2, LI Hui1,2, CHENG Yun-xuan1, JIAO Li-xin1,3*, LI Guo-dong1 (1.National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Chinese Research Academy of Environmental Sciences, Beijing 100012, China；2.College of Agriculture, Henan University of Science and Technology, Luoyang 471000, China；3.State Environmental P rotection Key Laboratory for Lake P ollution Control, State Environmental P rotection Key Laboratory of Drinking Water Source P rotection, Chinese Research Academy of Environmental Sciences, Beijing 100012, China). China Environmental Science, 2020,40(11)：4927~4935Abstract：The sediments of Baiyangdian Lake, Hengshui Lake, Yuqiao Reservoir, Songhua Lake, Dahuofang Reservoir and Xiaoxingkai Lake were selected as research objects. The contents of heavy metal elements including Cu, Zn, Pb, Cr and Ni in the sediments of the six lakes and reservoirs were determined with descriptive statistical analysis combined with multi-factor comparison of heavy metal pollution in other waters at home and abroad. The significant differences between the major sources of heavy metal pollution in the six lakes and reservoirs, the accumulation of heavy metals in the sediments and the similarities and differences with other waters at home and abroad were discussed. Heavy metal pollution in the sediments of Baiyangdian Lake, Hengshui Lake, Yuqiao Reservoir, Songhua Lake, Dahuofang Reservoir and Xiaoxingkai Lake was at a moderate to low level. There were differences in the main pollution sources between the six lakes. The heavy metal content of the sediment did not show a clear upward trend. Sediment heavy metal (Zn, Pb) are enriched in the six lakes, But the Pb content decreased compared with historical data, and the zinc content is generally higher than other regions. Dahuofang Reservoir sediments had the most heavy metal pollution. The average values of Cu, Zn, P b, Cr and Ni were 56.28mg/kg, 142.3mg/kg, 17.44mg/kg, 97.9mg/kg, 44.44mg/kg respectively. Xiaoxingkai Lake has the lowest heavy metal content. The average values of Cu, Zn, Pb, Cr and Ni are 2.41mg/kg, 63.90mg/kg, 13.37mg/kg, 56.36mg/kg, 26.09mg/kg respectively. Comprehensive risk assessment of the six lakes and reservoirs, Dahuofang Reservoir> Yuqiao Reservoir> Baiyangdian Lake> Hengshui Lake> Songhua Lake> Xiaoxingkai Lake. The overall potential ecological risk index of heavy metals is low.Key words：lake and reservoir；sediment；heavy metal；spatial distribution；ecological risk；Northern China湖泊在水源供给、渔业养殖、水运、小气候调节、物种多样性保护等多个方面都具有着不可替代的作用[1].重金属元素是一种典型的具有强烈积累性和持久污染能力的污染物[2].在进入水体后一部分与水中的各类物质相结合沉积于水底,伴随着环收稿日期：2020-03-17基金项目：国家科技基础性工作专项(2015FY110900-005)* 责任作者, 副研究员,****************.cn4928 中国环境科学 40卷境因素的改变逐渐释放,对水体造成持续的污染[3-4].目前以白洋淀、衡水湖、于桥水库、松花湖、大伙房水库和小兴凯湖等为代表的淡水湖库,随着供给侧结构性改革持续深化,城市人口的不断集中,造成污水排放量逐年递增,湖泊水资源的过度开发利用[5],北方水资源日趋紧张、水环境有恶化现象出现.其相关水质情况及水生态研究就显得很有必要,崔志丹等[6]研究发现,松花湖沉积物中PAHs污染程度较低.高秋生等[7]研究发现,白洋淀沉积物重金属Cd污染极为严重,应立刻采取修复措施.王乃珊等[8]认为,衡水湖沉积物重金属Hg存在富集现象,这与人类活动有密不可分的关系.目前已有研究多为针对单个湖泊的沉积物重金属研究,主要集中于水质的监测、水污染的治理等方面[6-9],缺乏横向的对比与北方多湖库的系统分析.所以,采用更科学的统计技术,系统的研究我国北方地区湖泊水资源的规律,不但可以为当地水质监测和水资源利用提供参考,也能为国家制定水资源相关政策提供数据支撑.本研究通过对北方六湖库沉积物中重金属含量特征分析,运用优劣解距离多指标综合评价模型和潜在生态风险指数法对数据进行整理,并探讨重金属分布特征与生态风险,结合各湖库差异对北方地区做出综合评价,以期为北方地区水体污染防控和湖库生态环境的保护提供科学依据.1材料与方法1.1 采样点设置与样品采集表1北方六湖库水环境基本特征Table 1 Water environment characteristics of six northernlakes and reservoirs水体沉积物采样湖库水温(℃) pH值COD(mg/L)粒径(µm)有机质(%)电导率(µS/cm)白洋淀 23.2 7.94 6.21 62.3 14.6 348.9 衡水湖 18.9 8.13 4.34 54.4 10.9 159.7 于桥水库 20.1 8.02 5.49 20.4 12.9 234.1 大伙房水库 12.6 7.49 5.89 34.9 12.7 364.2 松花湖 13.5 7.49 3.59 45.2 9.4 197.5 小兴凯湖 7.8 7.79 3.01 39.8 8.7 201.9 2018年8~12月分别对白洋淀、衡水湖、于桥水库、松花湖、大伙房水库和小兴凯湖进行采样,根据湖泊大小、河流入湖位置和湖库水环境情况(表1),在保证湖面全覆盖的基础上设置采样位置:白洋淀采样点15个、衡水湖采样点10个、于桥水库采样点9个、松花湖采样点29个(个别点位经、纬度缺失)、大伙房水库采样点10个、小兴凯湖采样点15个.泥样采集:每个采样点用抓斗式采泥器采集0~10cm沉积物样品500g,每个采集点采集3个平行样品,混合后为1个沉积物样品,置于密封袋中[10].所用样品采集后立刻密封并低温保存,上岸后立即将所采样品送回实验室进行指标测量.1.2 样品前处理与分析沉积物样品经过冷冻干燥,剔除动、植物残体等杂质,经研钵研磨后过100目筛,使用天平准确称取风干沉积物样品(0.5000±0.0010)g,放置于消解管中,加3mL氢氟酸和4mL王水均匀混合后120℃消解4h,再加入2mL王水、2mL高氯酸均匀混合后120℃消解4h,然后开盖在160℃进行赶酸,至颜色清亮,呈胶状固体为佳,拿出前补加2mL硝酸、10mL纯水,充分溶解后定容至50mL.完成前处理后,样品重金属含量使用电感耦合等离子体质谱仪(安捷伦ICP-MS 7500CX)进行测定.样品处理检测过程中,使用试剂纯度均为GR,所有器皿均使用35%硝酸浸泡24h后,用去离子水清洗并干燥.每批次样品均设置CK与标准样GBW07301a(GSD-1a),以保证前处理和数据的准确性.数据使用Excel、SPSS和Origin等软件进行分析.1.3统计分析方法本研究采用优劣解距离多指标综合评价模型和潜在生态风险指数法对北方六湖库的重金属污染情况进行分析,做出风险评价的同时对北方六湖库重金属污染的差异性、与国内外其他水体的异同点进行综合对比分析.优劣解距离多指标综合评价模型[11-12]也叫做逼近于理想解的技术,是系统工程中有限方案多目标决策分析的经典决策模型,该模型具有数据结果直观、数据稳定性高、精度高等特点,适用于多变量多因素的情况,目前已在医疗、经济、农业等领域中得到广泛认可.在采用优劣解距离多指标综合评价模型对各湖库重金属情况进行分析时,首先要建立n湖泊,m 种重金属的原始矩阵,用以消除不同指标不同量纲及其数量级的差异对评价结果的影响.该矩阵的最11期 李 捷等：北方湖库沉积物重金属区域特征及生态风险评价 4929优评价方案及最劣评价方案即为对所有数据进行评价的最低和最高标准. ()ij m n χ×=X (1) 原始矩阵经归一化处理:min max min /ij ij y =χχχχ−− (2) 在得到归一化处理的矩阵后,根据归一化矩阵,得到矩阵向量的最佳评价方案A +和最劣评价方案A -.由归一化矩阵计算出最佳评价方案A +和最劣评价方案A -分别为(0,0,0,0,0)和(1,1,1,1,1).然后根据各点位的归一化数据计算出其与最佳评价方案和最劣评价方案的距离D i +和D i -.即:+iD =i D −=(4)最后根据计算得出各指标与最佳评价方案A +的接近程度,即为对其的综合评价./()i C D D D −−+=+ (5)表2 重金属潜在生态风险指数等级划分Table 2 Classification of potential ecological risk index ofheavy metalsi r E 污染等级 RI 污染等级 <40 低 <150 轻度生态危害40~80 中 150~300 中等的生态危害80~160 较重 300~600 强的生态危害160~320 重 ≥320严重≥600很强的生态危害表3 土壤重金属背景值及毒性系数Table 3 Background value of soil heavy metal and toxicitycoefficient参数 Cu Zn Pb Cr Ni 土壤背景值 22.6 74.2 26 61 26.9 毒性系数51522潜在生态风险指数法[13]:该方法为瑞典的Hakanson 最先提出,其原理是通过对污染元素的含量、种类、毒性和水体对这种元素的敏感程度等因素进行指标量化,然后根据重金属潜在生态风险指数等级划分(表2)对重金属的潜在风险进行评级.计算公式:RI immii rri i=1i=1n C =E =T C ∑∑ (6)式中:E r i 是所测元素的潜在生态风险参照值;RI 是沉积物所测多元素的潜在生态风险参照值;C n i 为所测元素的实测值;C i 为所测元素的参照值,参照采用全国土壤背景值中的重金属背景值;T r i 为重金属的毒性系数,见表3.2 结果与讨论2.1 沉积物重金属分布特征如图1所示,北方六湖库沉积物重金属中Cu 含量为1.01~85.17mg/kg,均优于GB 15618-2018《土壤环境质量 农用地土壤污染风险管控标准(试行)》[14]Ⅰ类污染风险标准;Zn 含量为33.68~ 208.80mg/kg,除松花湖与大伙房水库个别点位接近或略高于Ⅰ类污染风险标准,属于Ⅱ类污染风险管制标准范围,其余均优于Ⅰ类污染风险标准;Pb 含量为1.14~87.91mg/kg,均优于Ⅰ类污染风险标准;Cr 含量为14.35~141.81mg/kg,优于Ⅰ类污染风险标准;Ni 含量为9.49~59.87mg/kg,优于Ⅰ类污染风险标准.对照全国土壤背景值[15]对沉积物中的重金属含量进行评价可发现,六湖库中大伙房水库沉积物重金属Cu 、Zn 、Pb 、Cr 、Ni 含量均高于土壤背景值,沉积物重金属Cu 、Zn 、Cr 、Ni 分别为56.28,142.3, 97.9,44.44mg/kg.其中Cu 含量最高,达到土壤背景值的2.49倍;小兴凯湖各项重金属指标均低于背景值,且Zn 含量为六湖最低,为63.9mg/kg;于桥水库Pb 含量最高,为59.84mg/kg.本研究结果与王祖伟等研究基本保持一致[3,16-20],六湖在重金属元素含量分布上存在显著差异,其中小兴凯湖沉积物重金属污染程度最低,大伙房水库重金属污染程度最高,且大伙房水库各重金属元素与土壤背景值存在明显差异,可见大伙房水库受到外来污染与自身扰动等因素的影响较大.通过整理国内外各水体沉积物重金属含量情况(表4).对比博斯腾湖、羊卓雍错、青海湖、昆仲错[21-23]等我国西北部湖库,北方六湖库沉积物Cu 含量除污染较重的大伙房水库(56.28mg/kg),高于西部湖库,其余含量相当;沉积物Zn 含量北方六湖库均高于西部;沉积物Pb 含量白洋淀、衡水湖、于桥水库高于西部地区,最高达到59.84mg/kg;沉积物Cr 含量除大伙房水库外,含量相当;Ni 含量北部地区与西部地区各湖库均在土壤背景值上下浮动.沉积物重金4930 中国环境科学 40卷属整体含量与西部湖库沉积物相比基本持平,略高于西部地区.图1 北方六湖库沉积物各重金属分布特征Fig.1 Distribution of heavy metals in sediments of six northern lakes and reservoirs 同巢湖、太湖、洞庭湖等[24-26]长江中下游湖库相比,北方六湖库的沉积物Cu、Zn含量略高于长江中下游湖库;而Pb、Cr、Ni的含量除了污染较为严重的大伙房水库外,其余均低于长江中下游湖库.沉积物重金属整体含量低于长江中下游湖库.同滇池、泸沽湖、百花湖、洱海等[27-30]西南部湖库相比,北方六湖库沉积物重金属整体含量水平较低,污染相比滇池较轻.同泸沽湖等湖体污染水平相当.北方六湖库整体重金属含量水平与国内其他湖库相比处于中等偏低水平,与美国、英国、墨西哥[31-33]等国家湖库相比沉积物重金属含量处于较低水平.同中部的南四湖相比,松花湖、小兴凯湖沉积物重金属含量低于南四湖;大伙房水库高于南四湖;其余3湖库相差不大;重金属整体含量同南四湖持平.但经济相对发达的珠江口相比重金属含量则明显高于北方六湖库.湖库沉积物重金属污染情况大致可分为基本无污染、轻微污染、重污染3种.白洋淀等北方六湖库都属于基本无污染范畴,整体水质保持良好,只有个别点位出现重金属元素超标情况;珠江口等属于轻微污染状态,Zn含量超标,其余处于污染较低水平;滇池、美国Narragansett湾则属于典型的重污染范畴,滇池沉积物中Zn、Pb、Cr为轻度污染,Cu为中度污染状态,整体多元素超标,水质较差.综上所述,与我国西南部、长江中下游、西北部、中部、南部等其他地区对比,北方六湖库沉积物重金属Zn的含量相对其他重金属较高,这可能与我国北11期李捷等：北方湖库沉积物重金属区域特征及生态风险评价 4931 部地区的土壤背景值有一定关系,且可能与北部地区电泳电镀等企业分布较多有关[23].与美国、英国、墨西哥等国外水域相比,沉积物重金属Zn、Pb含量明显高于背景值,有富集现象存在.不同湖库沉积物重金属的分布也具有显著的区域性,不同地区主要污染源存在明显差别,且存在人类频繁活动地区湖库沉积物重金属含量高于人类活动较少地区,工业密集区湖库沉积物重金属含量要明显高于工业非密集区,这表明除了土壤背景值导致的区域性差别外,人为扰动也是导致北方六湖库沉积物重金属含量存在差别的主要因素.表4北方六湖库沉积物重金属及国内外其他水体沉积物重金属含量Table 4 Heavy metal content in sediments of six northernlakes and reservoirs and heavy metal content in otherwaters at home and abroad湖库Cu(mg/kg)Zn(mg/kg)Pb(mg/kg)Cr(mg/kg)Ni(mg/kg)来源白洋淀28.83 91.19 45.26 48.53 25.51本研究衡水湖25.86 74.30 43.94 56.45 23.59本研究于桥水库37.86 74.97 59.84 61.13 30.28本研究大伙房水库56.28 142.30 17.44 97.90 44.44本研究松花湖 2.24 110.56 10.41 52.66 24.28本研究小兴凯湖 2.41 63.90 13.37 56.36 26.09本研究博斯腾湖17.17 40.20 13.21 34.14 18.10[21]羊卓雍错31.47 62.53 21.72 67.39 35.28[22]青海湖16.60 26.70 24.84 31.80 11.62[23]昆仲错32.5 64.7 17.25 102.3 95.2[22]滇池83.63 205.64 65.68 125.73 42.50[27]泸沽湖59.15 11.55 39.69 [30]百花湖22.4 58.3 20.0 29.1 [29]洱海110.5 167.3 60 130 80 [28]巢湖19.07 54.82 21.93 57.33 22.04[23]太湖26.03 61.33 25.72 85.74 38.85[24]洞庭湖10.20 63..99 44.55 79.34 [25]南四湖38.90 59.60 19.10 54.50 [23]珠江口71.47 196.84 56.64 100.79 [26]美国Narragansett湾190 250 140 155 [31]英国Thames河61 219 179 59 [32]墨西哥La Piedad河40.90 115.00 59.50 [33] 2.2沉积物重金属污染综合评价优劣解距离法主要优势在于对多个目标湖库归一化(表5)处理后,能够精准的对这些目标湖体的沉积物重金属含量情况进行量化,从而达到对多个目标横向对比分析的目的.采用优劣解距离法对六湖库的405个重金属含量数据进行整体的归一化处理,处理后对单一湖库数据建立底泥重金属的空间分布特征(图2),能够发现各湖库在沉积物重金属的空间分布特征上存在明显差异.表5北方六湖库沉积物重金属归一化指标Table 5 Normalized index of heavy metals in sediments of six lakes and reservoirs in North China湖库 Cu Zn Pb Cr Ni 白洋淀0.492 0.348 0.705 0.000 0.092 衡水湖0.437 0.133 0.678 0.160 0.000 于桥水库0.659 0.141 1.000 0.255 0.321 大伙房水库 1.000 1.000 0.142 1.000 1.000 松花湖0.000 0.595 0.000 0.084 0.033 小兴凯湖0.003 0.000 0.060 0.159 0.120 白洋淀沉积物重金属污染在空间分布上呈现西部采样点污染整体高于东部采样点,污染偏高的采样点主要分布在上游入湖口附近,可见其污染主要来源为外源污染,对比白洋淀历史文献数据,沉积物中重金属Cu、Ni、Cr含量保持相对稳定,Zn 和Pb在2008年前后达到最高,含量远超土壤背景值,之后出现了下降趋势,这与高秋生等[16]的研究一致,这种趋势可能与当地企业的迭代以及近几年白洋淀多次补水有直接关系.衡水湖作为衡水市和冀州市的水源地,为周边提供居民生活和工农业用水,其是“南水北调”的储水枢纽,主要水源来自黄河引流,湖体被分为东西两湖,且两湖常年有渔民捕鱼,旅游业发达,沉积物重金属污染空间分布上南部采样点污染高于北部采样点,且西部冀州小湖湖体采样点污染高于东部主湖体采样点,这可能是因为衡水湖的补水闸口在北部,补充进来的黄河水对底泥产生冲刷.对比张曼胤等[18]研究的衡水湖历史文献数据,发现沉积物重金属Cu、Cr波动较小,基本与土壤背景值持平,但重金属Zn上升趋势较为明显,且上升趋势较为一致,这可能与衡水湖捕鱼业发达,含Pb石油在周边排放较大有直接关系.于桥水库是拥有灌溉、蓄水、发电等功能的综合性大型水库,该水库目前是天津市的主要生活用水水源地.其沉积物重金属污染空间分布上为西部采样点污染高于中东部采样点,推测其主要原因为西部临近蓟州,有生产活动污水排入其中,且其上游河流有矿产企业分布,外源污染较多.对比侯迎迎等[34]研究的于桥水库历史文献数据,沉积物中除重金属Cu含量(37.86mg/kg)略有升高,达到背景4932 中国环境科学 40卷值的2.3倍外,其余重金属含量均呈现下降趋势.这可能与于桥水库上游黎河、沙河、淋河沿途的工厂污染排放治理有关.大伙房水库沉积物重金属污染西北部采样点最高,其主要原因是其上游浑河有红透山铜矿等矿产企业,且该企业是开采冶炼一体的综合性企业,已运营80多年,是大伙房水库的主要污染源头.对比罗燕等[17]研究大伙房水库的历史文献数据,发现沉积物中重金属Cu、Zn、Cr未发生明显变化,重金属Pb则从36.96mg/kg降至17.44mg/kg,下降近1倍.松花湖重金属污染在空间分布上5、22、25号点位污染较为严重,最高点位风险系数达到0.727,推测5号点位位于漂河镇附近,人类活动密集,且处于河湖道转弯处,重金属易产生淤积,22、25号点位湖道相对封闭,自净能力差,有景区分布是其主要污染原因.对比张颖等[12]的研究能够发现重金属Pb的含量也发生了明显的降低.小兴凯湖沉积物重金属风险为六湖库最低,空间分布上表现为东西采样点低,中部采样点高的趋势,2号点位白鱼滩附近污染相对较高,风险系数达到0.693,推测其主要原因是白鱼滩附近渔业活动造成的人为扰动,提高了其沉积物重金属含量.在与历史数据的对比中发现,北方六湖库整体保持了良好的水质,未出现沉积物重金含量明显上升的现象,且除小兴凯湖外其余5湖库的Pb含量均出现了下降,这种整体的趋势很可能与北方地区对有色金属冶炼等高污染企业重点治理、车辆限行减排、以及实施湖库休养生息等政策有直接关系.对六湖库重金属数据的污染差异性进行多重比较的横向综合评价,评价结果见表6.C i的值越小说明受污染程度越小;反之,受污染程度越大.根据C i 值对六湖库进行等次排序可发现,大伙房水库的C i 值最高(0.672),小兴凯湖的C i值最低(0.082),松花湖次之(0.214),衡水湖(0.383)、白洋淀(0.459)、于桥水库(0.499)分别位于3、4、5位置,这表明六湖库中大伙房水库污染程度相对最高,小兴凯湖最低,白洋淀、衡水湖、于桥水库差异性不显著.11期李捷等：北方湖库沉积物重金属区域特征及生态风险评价 4933图2 各湖库沉积物重金属采样点及综合评价指数Fig.2 Distribution of heavy metal sampling points in sediments of lakes and reservoirs and Comprehensive Evaluation Index表6北方六大湖库沉积物重金属综合评价Table 6 Comprehensive evaluation of heavy metals insediments of six northern lakes and reservoirs湖库D-D+C i等次白洋淀 1.367 1.611 0.459 4衡水湖 1.074 1.727 0.383 3于桥水库 1.413 1.421 0.499 5大伙房水库 2.061 1.005 0.672 6松花湖 0.602 2.216 0.214 2小兴凯湖 0.208 2.315 0.082 1在水环境的保护治理中,沉积物重金属污染带来的负面效应大,持续时间长,恢复难度高,会对当地整个生态环境带来巨大的破坏.重金属污染物进入水体后经过一系列迁移转化,参与和干扰各种环境化学过程和物质循环,最终以一种或多种形态长期存留在环境中,造成永久性的潜在危害.在对比历史数据及综合评价结果后发现,北方六湖库沉积物重金属污染程度并没有完全与经济发展水平保持一致,推测其原因,各湖库的主要定位和使用方式有区别,周围人文地理环境条件不同及当地对水体的监管治理力度有区别导致.但目前缺少水体上游及周边工业排放、农用化肥和渔业养殖等数据,因此北方六湖库之间重金属污染存在明显差异的原因还需要进一步探讨.2.3沉积物重金属潜在生态风险评价优劣解距离法主要优势在于对多个目标湖库归一化处理后污染程度的横向对比分析,主要侧重空间上的评价,但该方法并未考虑其对生物的毒害程度.潜在生态风险指数法是根据重金属元素特性,通过沉积学原理综合多元素协同作用、毒性水平和物种敏感性等条件对湖库沉积物的重金属含量情况进行评价的一种算法.如表7所示,从E r i可以看出,六湖库中于桥水库、大伙房水库潜在生态风险参数最高,其中Cu对大伙房水库的生态风险贡献最大达到12.45,Cu、Pb对于桥水库的生态风险贡献最大分别为8.38和11.51,松花湖与小兴凯湖的潜在生态风险指数最低,除松花湖和小兴凯湖的其余4湖库均存在Cu、Pb生态风险贡献偏大的情况,且Pb在白洋淀、衡水湖、于桥水库的含量均超过土壤背景值的2倍以上,这表明Cu、Pb两种重金属已在湖泊沉积物中发生富集,后期产生污染的风险较大,在湖库水体中,一般水生动植物生长发育的整个周期都在水内,因此在湖库被污染的情况下很容易在其体内积累大量的重金属元素,通过食物链转移到人体.因此应加强对这两种重金属元素入湖的监控.潜在生态风险评价法所得结论与综合评价法互相印证,所得结论保持一致.六湖库5项沉积物重金属潜在风险参数目前均处于污染等级低的档位,重金属潜在生态风险较低,但在北方工业发展逐步提速的今天也应当警惕重金属污染的可能性,提前做好各类预防措施.表7北方六湖库沉积物重金属潜在生态风险参数E r i、RITable 7 Potential ecological risk coefficient and index ofheavy metals in sediments of six northern lakes andreservoirs E r i、RIE r i湖库Cu Zn Pb Cr NiRI白洋淀 6.38 1.23 8.7 1.59 1.9 21.62衡水湖 5.72 1 8.45 1.85 1.75 20.37于桥水库8.38 1.01 11.51 2 2.25 26.69大伙房水库12.45 1.92 3.35 3.21 3.3 25.66松花湖 0.49 1.49 2 1.73 1.81 8.6小兴凯湖0.53 0.86 2.57 1.85 1.94 8.784934 中国环境科学 40卷3 结论3.1目前六湖库沉积物重金属含量并未出现明显上升的趋势,水环境保持较好.其中大伙房水库沉积物重金属污染最重.除小兴凯湖外其余5湖库的Pb 含量出现下降趋势.这表面明外源减少,Pb重新释放入水体,沉积物重金属Pb含量降低.3.2北方六湖库之间主要重金属污染源存在明显区别,人类频繁活动地区沉积物重金属含量高于人类活动较少地区,工业密集区湖库沉积物重金属含量高于工业非密集区,但没有呈现出随经济水平的提高重金属污染越来越重的趋势.这除了土壤背景值导致的区域性差别外,人为扰动因素也是导致北方六湖库沉积物重金属含量存在差别的主要因素.3.3对比国内外其他湖库沉积物重金属含量北方六湖库沉积物重金属含量较低,污染处于中等偏下水平,潜在生态风险污染等级均为低,沉积物重金属Zn的含量与其他地区相比存在含量偏高的情况. 3.4Cu和Pb为白洋淀、衡水湖、于桥水库、大伙房水库的潜在生态风险的主要贡献元素,污染风险相对较高.沉积物重金属生态风险和污染程度从高到低依次为大伙房水库、于桥水库、白洋淀、衡水湖、松花湖、小兴凯湖.参考文献：[1] 金相灿,王圣瑞,席海燕.湖泊生态安全及其评估方法框架 [J]. 环境科学研究, 2012,25(4):357-362.Jin X C, Wang S R, Xi H Y. 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基于多壁碳纳米管Nafion修饰电极的溶出伏安法测定大豆和大米重金属铅含量
中国油料作物学报Chinese Journal of Oil Crop Sciences基于多壁碳纳米管/Nafion修饰电极的溶出伏安法测定大豆和大米重金属铅含量王忠政1,2,3，洪琦1*（1.湖北大学生命科学学院，湖北武汉，430062；2.中国农业科学院油料作物研究所，湖北武汉，430062；3.农业部油料及制品质量监督检验测试中心，湖北武汉，430062）摘要：建立了一种测定大豆和大米中重金属铅含量的多壁碳纳米管/Nafion溶出伏安方法。
该方法对重金属铅的线性方程为y=4.66x+46.19，相关系数为0.994，线性范围0.1~20.0µmol/L。
实际样品测试中多壁碳纳米管/Nafion 材料对大豆中铅的样品回收率为99.50%~100.37%，相对标准偏差小于5.36%；对大米中铅的回收率为98.75%~ 101.25%，相对标准偏差小于5.63%。
该方法可适用于大豆和大米为主的粮油产品中重金属铅的检测，为加强食品安全保障提供技术支撑。
关键词：多壁碳纳米管；Nafion分散液；重金属铅；粮油产品中图分类号：S-3文献标识码：A文章编号：1007-9084（2020）03-0350-06Determination of heavy metal lead in soybean and rice use a multi-walled carbon nanotube/Nafion modi⁃fied electrode by stripping voltammetryWANG Zhong-zheng1,2,3，HONG Qi1*（1.School of life Science,Hubei University,Wuhan430062,China;2.Oil Crops Research Institute,Chinese Academy of Agricultural Science,Wuhan430062,China;3.Quality Inspection and Test Center for Oilseeds Products,Ministryof Agriculture and Rural Affairs,Wuhan430062,China）Abstract:A multi-walled carbon nanotube/Nafion modified electrode for determination of heavy metal ion lead in soybean and rice by stripping voltammetry was established.The linear regress equation was y=4.66x+ 46.19,with correlation coefficient of0.994.The detection limit was in the range of0.1~20µmol/L.The recoveries of lead in the soybean were in the range of99.50%~100.37%,with RSD less than5.63%.The recoveries of lead in the rice were in the range of98.75%~101.25%,with RSD less than5.63%.The method was applied to the detection of heavy metal ion lead in soybean and rice.It has safeguard effect to grain and oil products.Key words:multi-walled carbon nanotube；Nafion；heavy ion Pb；grain and oil products铅是我国常见粮油产品大豆和大米中主要的重金属污染物，可在人及动物体内蓄积，导致人体神经机能失调、肾功能损伤和贫血[1]。
Identification and characterization
Bioresource Technology 97 (2006) 1843–18490960-8524/$ - see front matter © 2005 Elsevier Ltd. All rights reserved.doi:10.1016/j.biortech.2005.08.021AbstractA unicellular alga displaying a high growth rate under heterotrophic growth conditions was isolated from soil and identi W ed as Chlo-rella sorokiniana . The optimal temperature for growth was 35°C and the optimal pH was 6.0–7.0. Glucose, sucrose, galactose, maltose,and soluble starch served as carbon sources supporting growth under dark conditions. The cell yield was 50g/l (wet weight) in a hetero-trophic medium containing 3% glucose. Isolated unicellular algae were highly resistant to heavy metals such as Cd 2+, of which the mini-mal inhibitory concentration was 4mM. Algae were capable of taking up the heavy metal ions Cd 2+, Zn 2+ and Cu 2+ at 43.0, 42.0 and 46.4 g/mg dry weight, respectively. Growth inhibition of Oryza sative shoots by 5ppm Cd 2+ in hydroponic medium was completely pre-vented by the addition of 0.25mg of wet Chlorella cells. These results indicated that this isolate was potentially useful for phytoremedia-tion by preventing environmental dispersion of heavy metals.© 2005 Elsevier Ltd. All rights reserved.Keywords:Bioremediation; Cadmium; Chlorella sorokiniana ; Green algae; Heterotrophic growth; Phytoremediation1. IntroductionMany metal ions are essential as trace elements, but at higher concentrations, they become toxic. Heavy metals are di Y cult to remove from the environment and are ultimately indestructible, unlike many other pollutants that can be chemically or biologically degraded (Ozaki et al., 2003).Today, heavy metals constitute a global environmental haz-ard. For example, environmental pollution by Cd 2+, arising mainly from mining, smelting, dispersal of sewage sludge (Hutton, 1983), and the use of phosphate fertilizers (Cris-anto Herrero and Lorenzo Martin, 1993) is increasing.Microorganisms could be used to clean up metal contami-nation by removing metal from contaminated water and waste streams, sequestering metals from soil and sediments,or solubilizing metals to facilitate their extraction. Bacteria and higher microorganisms have developed resistance totoxic metals and are able to make them innocuous. Micro-organisms respond to heavy metals using various defense systems, such as exclusion (Ortiz et al., 1992), compartmen-talization (Valls et al., 2000), complex formation (Wang et al., 1997), and synthesis of binding proteins, such as metallothioneins (Adamis et al., 2004). Microorganisms with unique abilities such as metal absorption, accumula-tion or resistance can be identi W ed among naturally occur-ring organisms. Alternatively, these systems can be utilized in engineering bacteria for remediation of polluted waters and soils. Thus, the use of microorganisms for decontami-nating heavy metals has attracted growing attention because there are several problems associated with pollu-tant removal using conventional methods. Bioremediation strategies have been proposed as an attractive alternative owing to their low cost and high e Y ciency (Mejare and Bülow, 2001).Heavy-metal-resistant microorganisms show us possible methods to prevent environmental contamination. The newly discovered metal sequestering properties of certain*Corresponding author. Tel./fax: +81 985 58 7218.E-mail address: a04109u@cc.miyazaki-u.ac.jp (N. Yoshida).1844N. Yoshida et al. / Bioresource Technology 97 (2006) 1843–1849types of fungi (Svoboda and Kalac, 2003) and algae (Chai-suksant, 2003) hold considerable promise. Heavy metals can be eliminated from polluted environments by utilizing their natural heavy metal disposing abilities. The objective of this study was thus to isolate and characterize a cad-mium-tolerant eukaryotic microorganism from soil and to determine its potential for reducing toxic heavy metals. Cadmium reduction by microorganisms has suggested the importance of microorganisms in bioremediation and envi-ronmental cleanup operations (Niu et al., 1993; Chen and Wilson, 1997; Morris et al., 1999). The tolerance of isolated cells to elevated Cd2+ in the environment and the biochemi-cal basis of this tolerance, as well as the metal adsorption capacity of these cells, were examined.2. Methods2.1. Isolation of heavy-metal-resistant microorganismsYPG media (peptone, 10g; yeast extract, 5g; glucose, 10g) was sterilized by autoclaving at 120°C for 15min. A sterilized solution of 0.5M CdCl2 through a Millipore W lter was aseptically added to the medium at a W nal concentra-tion of 2mM. Soil obtained from random areas was dis-solved in 10–20 volumes of sterilized physiological saline and was spread onto a YPG plate containing 2mM of Cd2+ and 50 g/ml of chloramphenicol. After incubation at 30°C for 3 days, colonies formed were removed and streaked onto another plate, and this was used as the experimental strain.2.2. Determination of chlorophyllThe growth at 30°C in YPG broth (pH 7.0) containing glucose was determined by measuring packed cell volume per liter of culture using a hematocrit and cell weight (dry weight of cells, g/l). Chlorophyll a and b levels were deter-mined by measuring the optical density at 660nm and 642.5nm in ethyl ether cell extract, and were calculated according to Je V rey’s equation (Je V rey, 1976). Cells were then observed by X uorescence microscopy (E xciter: 520–550nm, Dichroic mirror: 565nm, Emitter: 580nm) (Olym-pus, Tokyo).2.3. Saccharide utilizationThe pre-culture was maintained in 3ml of yeast extract peptone dextrose (YPG) broth (pH 7.0) at 30°C for 2 days in the dark. Assimilation of various carbon sources was investigated using MBM medium [KNO3, 25mg; MgSO4·7H2O, 7.5mg; K2HPO4, 7.5mg; KH2PO4, 17.5mg; NaCl, 2.5mg; CaCl2·2H2O, 1mg; Fe-mixture (FeSO4·7H2O, 1g; distilled water, 500ml), 0.1ml; A5-metal mixture (H3BO3, 286mg; MnSO4·7H2O, 250mg; ZnSO4·7H2O, 22.2mg; CuSO4·5H2O, 7.9mg; Na2MoO4, 2.1mg; distilled water 100 m1), 0.1ml; distilled water 99.8ml; pH 6.0] with or without 0.5% (w/v) of each saccha-ride. A total of 1ml of pre-cultured cells was inoculated into 100ml of MBA broth. MBA broth was then shaken at 150rpm at 30°C for 5 days. Growth was compared by mea-suring optical density at 550nm.2.4. Optimum pH and temperature for growthThe pre-culture was maintained in 3ml of YPG broth (pH 7.0) at 30°C for 2 days in the dark. The heterotrophic culture was performed using 100ml of YPG broth (pH 7.0) in each 300ml cotton plugged Erlenmeyer X ask by adding 1ml of the pre-culture broth, on a rotary shaker (100rpm) at 20–40°C for 4 days in the dark. The growth was com-pared by measuring the optical density at 550nm. The opti-mum pH for growth was determined using YPG broth that was adjusted to a desired pH value with 0.1N HCl or 0.1N NaOH.2.5. Ampli W cation and sequencing of 18S rDNAIsolated microorganisms were grown in 3ml of YPG broth at 30°C for 3 days by agitation. DNA was extracted from 1.5ml of culture broth (approximately 0.04g cells) using a DNA extraction kit (Isoplant II; Nippon Gene, Toyama) according to the manufacturer’s instructions. Sense and antisense primers were designed (5Ј-ACGGAGG ATTAGGGTTCGATTCCG-3Ј and 5Ј-GCTTCCATTG GCTAGTCGCCAATA-3Ј, respectively). Both primers were used in PCR with chromosomal DNA acting as a tem-plate. The reaction mixture contained 5 g of chromosomal DNA, 400pmol of each oligonucleotide primer, and 0.1U of Taq DNA polymerase in a volume of 50 l. Thirty ther-mal cycles of 94°C for 1min, 50°C for 1min, and 72°C for 1min, were carried out. PCR products were puri W ed by aga-rose gel electrophoresis. The resulting DNA fragment (1800 bp) was ligated into a pCRII vector (Invitrogen, CA, USA). The PCR-ampli W ed fragment was sequenced using the dideoxy chain termination method (Sanger et al., 1977). Searches for similar sequences were carried out using the BLAST program (Altschul Gapped BLAST 2001). Multi-ple alignments were run using GENETIX ver. 10. Distance matrix trees were constructed using Kimura’s two-para-meter model (Kimura, 1980).2.6. Metal resistance and minimum inhibitory concentrationsResistance of the isolated strain to cadmium chloride, cupric sulfate, zinc chloride, nickel chloride and aluminum chloride was determined by the dilution method (Nieto et al., 1989). Metal ions were added separately to YPG broth at concentrations of 1–10mM. YPG broth without the metal ions was also inoculated with the isolated strain for use as controls. Each broth was cultured at 30°C for 4 days by agitation at 100rpm. The minimum inhibitory con-centration (MIC) was de W ned as the lowest concentration of metal that completely inhibited growth.N. Yoshida et al. / Bioresource Technology 97 (2006) 1843–184918452.7. Uptake of heavy metals by isolated microorganismThe isolated microorganism was cultured in YPG broth at 30°C for 4days and was then harvested by centrifugation at 2000g for 15min. Next, 100mg (dry weight) of harvested cells were suspended in 100ml of 10mM Tris–HCl bu V er (pH 7.0) containing 1–5mg of either Cd2+, Zn2+ or Cu2+, or 2.5mg each of Cd2++Zn2+, Cu2++Zn2+, and Cd2++Cu2+. These suspended solutions were shaken at 100rpm at 30°C. Residual heavy metals in the upper phase following centri-fugation at 2000g for 15min were quanti W ed by atomic absorption spectrophotometry (Shimadzu, Japan).2.8. Possibility of bioremediationRice seeds (Oryza sative L. cv. Koshihikari) were surface sterilized in 70% (v/v) aqueous ethanol for 15min, rinsed 5 times with distilled water and allowed to germinate on a sheet of moist W lter paper at 25°C with a 12-h photoperiod in a growth chamber. Light was provided from above with a white X uorescent tube. After 3days, uniform seedlings (n D30) were transferred onto a sheet of plastic mesh (3£3cm) that was X oated on distilled water (100ml) in the presence or absence of 5mg/l of Cd2+ in plastic containers (5£5£8cm). Next, 0.03–0.50g (wet weight) of the isolated microorganism was added to the media. Seedlings were grown at 25°C with a 12-h photoperiod. The water in the plastic container was kept at the same level by adding dis-tilled water at 24-h intervals and only the roots of the seed-lings were immersed in the water during the incubation. After 3 weeks, the shoot length was measured.3. Results3.1. Isolation of heavy-metal-resistant microorganismsSoil samples were collected from various districts in Japan and more than a 100 strains were found to be Cd2+ and chloramphenicol resistant. A yeast-like strain that formed large green colonies was selected and its physiologi-cal pro W le was subsequently examined. This strain, desig-nated ANA9, was then used as the experimental organism. The cells of the isolated microorganism were always spheri-cal and were 5.35–8.56 m in diameter. The cells were grown on YPG and were always green, regardless of light-ing conditions.3.2. Determination of chlorophyllStrain ANA9 was observed as bright red cells on X uores-cence microscopy, thus indicating that it possessed chloro-plasts. Chloroplasts were excited at 520/550nm and emission signals were collected at wavelengths above 580nm. The heterotrophic cells contained chlorophylls a and b (96 and 34 g/mg dry weight, respectively) and carotenoids (2.2 g/mg dry weight). Chlorophylls were con-stituents of chloroplasts, but were synthesized even under dark conditions when cells grew by metabolizing an organic carbon source.3.3. Saccharide utilizationUtilization of organic carbon sources was investigated on MBM medium containing 0.5% of each sample in the dark. Only a few were found to support growth as the sole carbon source: glucose, sucrose, maltose, galactose and sol-uble starch. Cellobiose, sorbose, ra Y nose, xylose and lac-tose were unable to support growth under the experimental conditions used. Most algal strains showed higher growth rates under autotrophic conditions than under heterotro-phic conditions. In contrast to these strains, heterotrophic growth rate of strain ANA9 was rather higher than the autotrophic rate. Chlorella ellipsoidea(Yamada and Shi-maji, 1986) was used as a control and was unable to grow under heterotrophic or dark conditions.3.4. Optimum pH and temperature for growthThe optimal temperature and pH for growth under het-erotrophic conditions without light were found to be 35°C and pH 6.0–7.0, respectively (Fig.1). Isolated strain ANA9 did not exhibit substantial growth at pH>8.0 or <4.0. The growth at 40°C was suppressed, thus suggesting that this was not a thermophilic microorganism.1846N. Yoshida et al. / Bioresource Technology 97 (2006) 1843–18493.5. Heterotrophic growthThe cells were cultured on YPG medium in which glucose concentration was adjusted 0–4% (w/v). As shown in Fig.2, the optimum concentration of glucose for growth was 3%, where the cell yield was 50g/l after culturing at 30°C for 120h. The growth rate and yield of a number of micro-algae have been reported (Endo et al., 1974). Compared with these strains, isolated strain ANA9 can be recognized to have a much higher growth under heterotrophic conditions.3.6. Ampli W cation and sequencing of 18S rDNAThe small subunit ribosomal RNA gene of strain ANA9 was ampli W ed from bulk genomic DNA by PCR. The iso-lated small subunit rRNA sequence was 1870 nucleotides long and showed similarities with other known sequences from green algae, ranging in homology from 98% with Chlorella sorokiniana (Huss et al., 1999) to 95% with Chlo-rella saccharophila (Krienitz et al., 1996). Strain ANA9 was thus identi W ed as belonging to the genus Chlorella. Strain ANA9 was subsequently identi W ed as belonging to the spe-cies C. sorokiniana and was therefore designated C. soroki-niana ANA9.3.7. Metal resistance and minimum inhibitory concentrationsThe MICs of 5 metal ions tested against strain ANA9 are shown. For the purpose of de W ning metal resistance, strains that were not inhibited by 1mM of heavy metal ions were regarded as resistant (Nieto et al., 1989). The isolate was resistant to multiple metals. The isolated microorgan-ism was particularly resistant to the W ve metal ions, the highest MIC was seen for Cd2+ (4mM). Strain ANA9 was able to grow in YPG broth containing Cd2+ at concentra-tions of 3mM. This strain had a higher resistance to Cu2+ and Al3+ (MICs of 8mM and 7mM, respectively) than to Cd2+, Zn2+ and Ni2+ (MICs of 4mM). In the present study, toxicity of metal ions was ranked as follows: Cd2+D Zn2+D Ni2+>Al3+>Cu2+.3.8. Uptake of heavy metals by the isolated microorganismFig.3 shows the time course of heavy metal uptake by the isolated microorganism. The amount of Cd2+, Zn2+ and Cu2+ taken up by the cells increased rapidly during the W rst 30min after the application of cells, and then steadily increased with time. When the initial amount of Cd2+ was 5mg, 55% was taken up from the Tris–HCl bu V er after 24hN. Yoshida et al. / Bioresource Technology 97 (2006) 1843–18491847and 90% was taken up after 48h. When the initial amount of Cd 2+ was 2.5 and 1mg, 90% of the Cd 2+ was also taken up after 48h. When the initial amount of Zn 2+ was 5mg, the reduction in Zn 2+ concentration was 75% after 24h and 85% after 48h. The adsorption of Cu 2+ by the isolated strain was W rst very rapid within the W rst 30min, resulting in more than 80% being taken up. The maximum amounts of Cd 2+, Zn 2+, and Cu 2+ taken up by the cells were 43.0,42.0, and 46.4 g, respectively, per milligram of dry weight.The e V ects of the presence of co-ions in the solution on the heavy metal uptake capacity of the isolated organism were also examined. As seen in Fig.4, Zn 2+ had no e V ect on Cd 2+ uptake, despite the 2.5mg co-ion concentration. The Cd 2+ and Zn 2+ uptake capacity of the isolated strain wasprogressively and negatively a V ected by Cu 2+, indicating that the isolated strain had a higher a Y nity for Cu 2+ than for Cd 2+ and Zn 2+. After 48h of incubation, 50% and 80%of the Zn 2+ and Cu 2+, respectively, was removed from the solution. After 48h incubation, 60% and 80% of the removed Cd 2+ and Cu 2+, respectively, was accumulated intracellularly or adsorbed on the cell surface. The isolate exhibited a higher selectivity for Cu 2+ than for other the metal ions and the preference was as follows: Cu 2+>Cd 2+>Zn 2+.The distribution and binding states of Cd 2+ in the isolated microorganism were examined by washing with 10mM EDTA solution. Isolated microorganism cells were suspended in 10mM EDTA solution (pH 5.0) by agitation at room temperature after incubation with Cd 2+ for 48h.After 5min in the EDTA solution, the supernatant was col-lected by centrifugation at 2000g for 20min. None of Cd 2+taken up in the living cells was released by washing with E DTA. This indicates that the cells incorporated Cd 2+intracellularly.3.9. Potential for bioremediationThe e V ectiveness in reversing Cd 2+-inhibited plant growth was determined. At concentrations of 5mg/l, Cd 2+inhibited hypocotyl and shoot growth of rice seedlings. The shoot growth of rice seedlings was restricted to 60% in the presence of Cd 2+ when compared with control rice seed-lings. The shoot growth of rice inhibited by Cd 2+ increased with Chlorella cell concentration. As little as 0.25g (wet weight) of Chlorella cells prevented Cd 2+ toxicity. Smaller amounts, 0.03–0.1g (wet weight), of Chlorella cells had no e V ect on the growth inhibition by Cd 2+ (Fig.5). These results suggest that the isolated Chlorella cells had the potential for bioremediation of rice husks by preventing Cd 2+ accumulation near the plants.4. DiscussionCadmium was an important environmental pollutant and a potent toxicant to bacteria, algae and fungi. MechanismsFig.5. E V ects of Cd 2+ on rice shoots grown under hydroponic conditions with or without isolated strain ANA9. Vertical bars represent SE (n D 30).1848N. Yoshida et al. / Bioresource Technology 97 (2006) 1843–1849of Cd2+ toxicity and resistance varied depending on theorganism. However, the form of the metal and the environ-ment it is studied in play an important role in how Cd2+ exerted its e V ects and how organisms respond. A widerange of Cd2+ concentrations have been used to designateresistance in organisms. To date, however, no particularconcentration has been speci W ed as applicable to all species under standardized conditions. Cadmium exerted its toxice V ects over a wide range of concentrations. In most cases,algae and cyanobacteria were the most sensitive organisms,while bacteria and fungi appear to be more resistant. In some bacteria, plasmid-encoded resistance could lead toreduced Cd2+ uptake, although some Gram-negative bac-teria without plasmids were just as resistant as bacteriacontaining plasmids encoding Cd2+ resistance.Insu Y cient information is available on the genetics ofCd2+ uptake and resistance in cyanobacteria and algae, andmechanisms remain largely unknown. Cd2+ was toxic tothese organisms, causing severe inhibition of physiological processes, such as growth, photosynthesis and nitrogen W xation, at concentrations of less than 2ppm, and often in the ppb range (Perfus-Barbeoch et al., 2002). Cd2+ alsocaused pronounced morphological aberrations in these organisms, and these were probably related to deleterious e V ects on cell division. Such e V ects may be direct or indi-rect, perhaps as a result of Cd2+ e V ects on protein synthesis and cellular organelles such as mitochondria and chloro-plasts. Cd2+ accumulated internally in algae (Perez-Rama et al., 2002) as a result of a two-phase uptake process. The W rst phase involved rapid physicochemical adsorption of Cd2+ onto cell wall binding sites, which were probably pro-teins and/or polysaccharides. This was followed by a lag period and a steady intracellular uptake. This latter phase was energy dependent and may involve the transport sys-tems used to accumulate other divalent cations, such as Mn2+ and Ca2+. Some data indicated that Cd2+ resistance and possibly uptake in algae and cyanobacteria were controlled by plasmid-encoded genes (Ren et al., 1998). Although considerable information is available on Cd2+toxicity to and uptake in fungi, further work was clearly needed in several areas. There was little information regarding Cd2+ uptake by microalgae, W lamentous fungi, or even in yeast, while information on speci W city, kinetics, and mechanisms of Cd2+ uptake was limited.Chlorella sp. is a unicellular green alga having worldwidedistribution in all aquatic environments, soil (Koelewijnet al., 2001) and tree bark (Cho et al., 2002). It is also found as a symbiote in animals such as Hydra viridis(Habetha and Bosch, 2005). Chlorella only reproduces asexually, with the mature cell dividing mitotically to produce autospores. Chlorella is a very small alga with a single chloroplast, and it does not possess an eyespot or X agella. Algae of genus Chlorella can grow photosynthetically, and certain strains among these are known to grow in the dark by utilizing organic carbon sources (Rehman and Shakoori, 2001). It has been reported that the growth rate of algae was gener-ally much slower than bacteria and yeast, and dark hetero-trophic growth was even slower. However, if strains of algae could be found that possess higher growth rates under heterotrophic conditions, then production of algal proteins by industrial means may become more practical.C. sorokiniana ANA9, which had a much higher growth rate under heterotrophic conditions than other reported strains, was successfully isolated from soil. This isolated alga possessed a high growth rate (50g/l) in batch culture.The heavy metal binding potential of Chlorella sp. was W rst discovered in the mining industry, and metal-resistant algae have since been reported in a number of studies. Matsunaga et al. (1999) screened marine microalgae for e Y cient Cd2+ removal with the aim of onsite heavy metal removal from the marine environment. They reported a maximum uptake in Chlorella of 39.4 g Cd2+/mg dry cells, which was higher than that of any other previously charac-terized microalgae. The maximum amounts of Cd2+, Zn2+, and Cu2+ taken up by the present isolate were 43.0, 42.0, and 46.4 g, respectively, per milligram (dry weight). Thus, the isolated C. sorokiniana ANA9 had the highest metal adsorption ever reported for algae.Agricultural soils were primarily contaminated with Cd2+ due to the excessive use of phosphate fertilizers, dis-persal of sewage sludge and atmospheric deposition. Cd2+ was readily taken up by numerous crops including cereals, potatoes, rice and fruits (Ingwersen and Streck, 2005). Con-sumption of rice grown in paddy soils contaminated with Cd2+, Cr6+ or Zn2+ may pose a serious risk to human health, because 22–24% of the total metal content in rice biomass was concentrated in the rice grains (Wang et al., 2003). Thus, contamination by Cd2+ is increasing in both human food and overall in the agricultural environment. Plants readily take up Cd2+ from the soil. However, expo-sure to high levels of Cd2+ resulted in reduced rates of pho-tosynthesis, chlorosis, growth inhibition, browning of root tips, decreased water and nutrient uptake, and ultimately death (Marcano et al., 2002). Phytoremediation technolo-gies are becoming recognized as cost-e V ective methods for remediating sites contaminated with toxic metals at a frac-tion of the cost of conventional technologies, which include soil replacement, solidi W cation and washing strategies. Phy-toremediation is de W ned as the use of plants for environ-mental cleanup, and in terms of phytoremediation of heavy metals, is divided into three categories; (1) phytoextraction, in which metal-accumulating plants are used to transport and concentrate metals from the soil in harvestable parts of roots and above-ground shoots; (2) rhizo W ltration, in which plant roots absorb, precipitate and concentrate toxic metals from polluted e Z uents; and (3) phytostabilization, in which heavy-metal-tolerant plants are used to reduce the mobility of heavy metals, thereby reducing the risk of further environmental degradation by leaching into ground water or by airborne spread. Here, we identi W ed the potential for metal-accumulating Chlorella to reduce the mobility of heavy metals in soil. As shown in Fig.5, our results indicated that the isolated C. sorokiniana ANA9 may be useful in preventing Cd2+ di V usion in the soil environment.N. Yoshida et al. / Bioresource Technology 97 (2006) 1843–18491849Further investigation of the e V ects of other factors on adsorption, such as ions in water and pH, will contribute to further optimizing the adsorption e Y ciency of this Chlo-rella strain.ReferencesAdamis, P.D., Gomes, D.S., Pereira, M.D., Freire de Mesquita, J., Pinto, M.L., Panek, A.D., E leutherio, E.C., 2004. The e V ect of superoxide dismutase de W ciency on cadmium stress. J. Biochem. Mol. Toxicol. 18, 12–17. Chaisuksant, Y., 2003. Biosorption of cadmium (II) and copper (II) by pretreated biomass of marine alga Gracilaria W sheri. Environ. Technol.24, 1501–1508.Chen, S., Wilson, D.B., 1997. Construction and characterization of Esche-richia coli genetically engineered for bioremediation of Hg2+-contami-nated environments. Appl. Environ. Microbiol. 63, 2442–2445.Cho, H.H., Park, H.H., Kim, J.O., Choi, T.J., 2002. Isolation and character-ization of Chlorella viruses from freshwater sources in Korea. 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The occurrence of chlorophyll c1 and c2 in algae.J. Phycol. 12, 349–354.Kimura, M., 1980. A simple method for estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. J. Mol. Evol. 16, 111–120.Koelewijn, H.P., de la Guerie, P., Bell, G., 2001. Variation in growth rate in a natural assemblage of unicellular green soil algae. Heredity 87, 162–171. Krienitz, L., Huss, V.A.R., Huemmer, C., 1996. Picoplanktonic Choricys-tis-species (Chlorococcales, Chlorophyta) and the misconception of Nannochloris-like algae. Phycologia 35, 332–341.Marcano, L., Carruyo, I., Del Campo, A., Montiel, X., 2002. E V ect of cad-mium on the nucleoli of meristematic cells of onion Allium cepa L.: an ultrastructural study. Environ. Res. 88, 30–35.Matsunaga, T., Takeyama, H., Nakao, T., Yamazawa, A., 1999. Screening of marine microalgae for bioremediation of cadmium-polluted sea-water. J. Biotechnol. 70, 33–38.Mejare, M., Bülow, L., 2001. Metal-binding proteins and peptides in bio-remediation and phytoremediation of heavy metals. Trends Biotech-nol. 19, 67–73.Morris, C.A., Nicolaus, B., Sampson, V., Harwood, J.L., Kille, P., 1999.Identi W cation and characterization of a recombinant metallothionein protein from a marine alga, Fucus vesiculosus. Biochem. J. 338, 553–560.Nieto, J.J., Fernandez-Castillo, R., Marquez, M.C., Ventosa, A., Quesada,E., Ruiz-Berraquero,F., 1989. Survey of metal tolerance in moderatelyhalophilic eubacteria. Appl. Environ. Microbiol. 55, 2385–2390.Niu, H., Xu, X.S., Wang, J.H., 1993. Removal of lead from aqueous solu-tions by Penicillium biomass. Biotechnol. Bioeng. 42, 785–787.Ortiz, D.F., Kreppel, L., Speiser, D.M., Scheel, G., McDonald, G., Ow,D.W., 1992. Heavy metal tolerance in the W ssion yeast requires an ATP-binding cassette-type vacuolar membrane transporter. E MBO J. 11, 3491–3499.Ozaki, T., Kimura, T., Ohnuki, T., Yoshida, Z., Francis, A., 2003. Associa-tion mechanisms of Europium(III) and Curium(III) with Chlorella vul-garis. J. Environ. Toxicol. Chem. 22, 2800–2805.Perez-Rama, M., Alonso, J.A., Lopez, C.H., Vaamonde, E.T., 2002.Cadmium removal by living cells of the marine microalga Tetraselmis suecica. Bioresour. Technol. 84, 265–270.Perfus-Barbeoch, L., Leonhardt, N., Vavasseur, A., Forestier, C., 2002.Heavy metal toxicity: cadmium permeates through calcium channels and disturbs the plant water status. Plant J. 32, 539–548.Rehman, A., Shakoori, A.R., 2001. Heavy metal resistance Chlorella spp., isolated from tannery e Z uents, and their role in remediation of hexa-valent chromium in industrial waste water. Bull. E nviron. Contam.Toxicol. 66, 542–547.Ren, L., Shi, D., Dai, J., Ru, B., 1998. Expression of the mouse metallothio-nein-I gene conferring cadmium resistance in a transgenic cyanobacte-rium. FEMS Microbiol. Lett. 158, 127–132.Sanger, F., Nicklen, S., Coulson, A.R., 1977. DNA sequencing with chain-terminating inhibitors. Proc. Natl. Acad. Sci. USA 74, 5463–5467.Svoboda, L., Kalac, P., 2003. Contamination of two edible Agaricus spp.mushrooms growing in a town with cadmium, lead, and mercury. Bull.Environ. Contam. Toxicol. 71, 123–130.Valls, M., de Lorenzo, V., Gonzalez-Duarte, R., Atrian, S., 2000. Engineer-ing outer-membrane proteins in Pseudomonas putida for enhanced heavy-metal bioadsorption. J. Inorg. Biochem. 79, 219–223.Wang, C.L., Michels, P.C., Dawson, S.C., Kitisakkul, S., Baross, J.A., Kea-sling, J.D., Clark, D.S., 1997. Cadmium removal by a new strain of Pseudomonas aeruginosa in aerobic culture. Appl. Environ. Microbiol.63, 4075–4078.Wang, Q.R., Cui, Y.S., Liu, X.M., Dong, Y.T., Christie, P., 2003. Soil con-tamination and plant uptake of heavy metals at polluted sites in China.J. Environ. Sci. Health Part A: Toxic Hazard Subst. Environ. Eng. 38, 823–838.Yamada, T., Shimaji, M., 1986. Nucleotide sequence of the 5S rRNA gene from the unicellular green alga Chlorella ellipsoidea. Nucleic Acids Res. 14, 9529.。
肥料样品 英语
肥料样品英语Fertilizer SampleThe world of agriculture has undergone a remarkable transformation in recent decades, with advancements in technology, innovative farming practices, and an increasing emphasis on sustainable resource management. At the heart of this evolution lies the critical role of fertilizers, which have become integral to enhancing crop yields, improving soil fertility, and ensuring food security for a growing global population.In this context, the analysis and evaluation of fertilizer samples play a crucial role in ensuring the quality and efficacy of these essential agricultural inputs. Fertilizer samples serve as the foundation for understanding the composition, nutrient content, and potential environmental impact of various fertilizer products. By conducting thorough examinations of these samples, researchers, agronomists, and regulatory bodies can make informed decisions that contribute to the development of more effective and environmentally responsible fertilizer formulations.One of the key aspects of fertilizer sample analysis is thedetermination of the nutrient content. Fertilizers are typically formulated to provide a specific balance of essential macronutrients such as nitrogen, phosphorus, and potassium, as well as various micronutrients that are vital for plant growth and development. The accurate quantification of these nutrient levels is crucial for ensuring that the fertilizer application rates are optimized to meet the specific needs of different crops and soil conditions.In addition to nutrient content, the analysis of fertilizer samples also encompasses the evaluation of potential contaminants or impurities. Heavy metals, pesticide residues, and other undesirable substances can be present in some fertilizer products, which can have detrimental effects on soil health, water quality, and the overall sustainability of agricultural systems. By conducting rigorous testing and analysis, researchers can identify and address these potential issues, ultimately contributing to the development of safer and more environmentally responsible fertilizer products.Another important aspect of fertilizer sample analysis is the assessment of physical and chemical properties, such as pH, particle size distribution, and solubility. These characteristics can significantly influence the effectiveness and application methods of the fertilizer, as well as its compatibility with various soil types and environmental conditions. By understanding these properties, agronomists and farmers can make informed decisions about the most appropriatefertilizer formulations and application strategies for their specific needs.The process of fertilizer sample analysis typically involves a series of well-established laboratory techniques and analytical methods. These may include spectroscopic analysis, chromatography, mass spectrometry, and various wet chemistry techniques, all of which are designed to provide accurate and reliable data on the composition and characteristics of the fertilizer samples.The insights gained from the analysis of fertilizer samples have far-reaching implications for the agricultural industry. The data generated from these analyses can inform the development of new fertilizer products, the optimization of existing formulations, and the implementation of more effective and sustainable fertilizer management strategies. Additionally, the information derived from fertilizer sample analysis can support regulatory frameworks, ensuring that fertilizer products meet established quality standards and environmental regulations.In conclusion, the analysis of fertilizer samples is a critical component of modern agriculture, contributing to the advancement of sustainable and efficient farming practices. By leveraging the knowledge and insights gained from these analyses, researchers, agronomists, and policymakers can work collaboratively to developinnovative fertilizer solutions that address the evolving needs of global food production while minimizing the environmental impact. As the world continues to grapple with the challenges of food security and environmental stewardship, the importance of fertilizer sample analysis will only grow, making it a vital tool in the pursuit of a more sustainable and prosperous agricultural future.。
水基钻屑用作基质对植物生长和重金属富集特征的影响
土 壤 (Soils), 2020, 52(5): 1043–1049①基金项目：江苏省水利科技项目(2017011)、江苏省重点研发计划项目(BE2018759)、江苏高校优势学科建设工程项目和重庆市科委–社会事业与民生保障科技创新专项重点研发项目(cstc2017shms-zdyfx0033)资助。
* 通讯作者作者简介：高昊辰(1994—)，男，安徽芜湖人，硕士研究生，主要从事盐渍土改良绿化方面的研究。
DOI: 10.13758/ki.tr.2020.05.024高昊辰, 刘广明, 陈金林, 等. 水基钻屑用作基质对植物生长和重金属富集特征的影响. 土壤, 2020, 52(5): 1043–1049.水基钻屑用作基质对植物生长和重金属富集特征的影响①高昊辰1,2，刘广明2*，陈金林1*，张 春3，张凤华4，黄真真1,2，王秀萍5，王相平2(1 南京林业大学南方现代林业协同创新中心，南京 210037；2 中国科学院南京土壤研究所，南京 210008；3 重庆市涪陵页岩气环保研发与技术服务中心，重庆 408000；4 石河子大学，新疆石河子 832003；5河北省农林科学院滨海农业研究所，河北唐山 063200)摘 要：通过将水基钻屑与土壤和(或)腐熟污泥以一定比例混合形成基质，在进行定量淋洗脱盐的基础上，研究了金叶女贞与狗牙根在该种基质上的生长状况与重金属富集特征。
结果表明：经过淋洗，配比基质盐分、养分等主要理化指标满足植物生长需求，重金属含量符合CJT340—2016《绿化种植土壤》标准，满足绿化植物生长所需的环境质量要求。
金叶女贞与狗牙根生物量的积累在不同配比基质中存在显著差异，其中在水基钻屑与土壤质量配比为10∶1与10∶2的基质中生物量最高。
对于重金属的富集，金叶女贞与狗牙根在不同配比基质中存在一定差异，二者对镉、铅、铜存在富集作用。
可见，水基钻屑合理配比后可作为基质用作绿化种植。
中国北部干旱地区使玉米产量增加且实现生态友好型的超级吸收聚合物
African Journal of Biotechnology Vol. 10(24), pp. 4887-4894, 6 June, 2011Available online at /AJBISSN 1684–5315 © 2011 Academic JournalsFull Length Research PaperSuperabsorbent polymers (SAP) enhance efficient and eco-friendly production of corn (Zea mays L.) in drought affected areas of northern China M. Robiul Islam1, 2, 3, Xuzhang Xue2, Sishuai Mao1,2, Xingbao Zhao4, A. Egrinya Eneji5 andYuegao Hu1*1College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, People’s Republic of China.2National Research Center for Intelligent Agricultural Equipments, Beijing 100097, People’s Republic of China.3Department of Agronomy and Agricultural Extension, Rajshahi University, Rajshahi 6205, Bangladesh.4Beijing Hanlisorb Polywater Hi-Tech. Co. Ltd. Beijing 100081, People’s Republic of China.5Department of Soil Science, University of Calabar, Calabar, Nigeria.Accepted 14 March, 2011In arid and semiarid regions of northern China, there is an increasing interest in using reduced rate of chemical fertilizer along with water-saving superabsorbent polymer (SAP) for field crop production. The objective was to evaluate the effectiveness of different rates of SAP (low, 0.75; medium, 11.3 and high,15.0 kg ha-1) against half amount of conventional standard rate of chemical fertilizer for summer corn(Zea mays L.) production in a drought-affected field of northern China. Corn yield increased following SAP application by 11.2% under low 18.8% under medium and 29.2% under high rate with only half amount (150 kg ha-1) of fertilizer compared with control plants, which received conventional standard fertilizer rate (300 kg ha-1). At the same time plant height, stem diameter, leaf area, biomass accumulation and relative water content as well as protein and sugar contents in the grain also increased significantly following SAP treatments. The optimum application of SAP in the study area would be 15 kg ha-1 as it brings progressive increase in corn growth and also maintain proper nutrients balance in the soil after harvest. Other rates are not sufficient to maintain proper plant growth or soil nutrient balance against half fertilizer. We suggest that, the application of SAP at 15 kg ha-1 plus only half the amount of conventional fertilizer rate (150 kg ha-1) would be a more appropriate practice for sustainable corn production under arid and semiarid conditions of northern China or the areas with similar ecologies.Key words: Corn, drought stress, fertilizer use efficiency, northern China, superabsorbent polymer. INTRODUCTIONIn arid and semiarid regions of northern China, there is an increasing interest in using reduced rate of chemical fertilizer along with water-saving superabsorbent polymer (SAP) for field crop production. China is one of the world’s most water-deficient economies and water scarcity is *Corresponding author. E-mail: huyuegaocau@. Tel: (86)10 62733847. Fax: (86) 10 62732441.Abbreviations:SAP,Superabsorbent polymer; RWC,relative water content; WAS,weeks after sowing; FW,fresh weight; AGB, above ground biomass accumulation; CP, crude protein; ; NCP, North China plain. viewed as a major threat to long-term food security. While the agricultural sector is still by far the largest user of China’s water resources, rapid economic and popu-lation growth is generating rising demand for urban and industrial use, increasing pressure on water supplies. On the other hand, fertilizer consumption in China is also challenging the acceptance limit of resource and environ-ment.China has a large region of dry land in the north, which accounts for about 56% of the nation’s total land area but only 24% of country’s water resources (Xin and Wang, 1999). The North China Plain (NCP) is one of the most important wheat and maize production areas in China. The main cropping system in this region is wheat and4888 Afr. J. Biotechnol.maize double cropping in a year producing about 29.6% of the nation's food, including about half of the wheat production and third of the maize production (NBSC, 1998). The average requirement of water for crop pro-duction is about 810 mm (450 mm for wheat and 360 mm for maize) whereas; the mean annual rainfall is only about 550 mm (Liu et al., 2001). Irrigation is critical for maintaining high crop yield, especially northern China, where about 75% of the agricultural land is irrigated, consuming 70 to 80% of the total water resource alloca-tion in the region (Liu et al., 2001). In recent years, however, increased water deficits associated with over-use use of surface water, declining groundwater levels, water pollution and soil salinization are threatening the sustainability of agricultural production in the region (Hu et al., 2005; Liu et al., 2001; Wang et al., 2001). The water supply for agricultural production will unavoidably decrease with the increasing demands from domestic and industrial water users. At the same time, the agricul-tural water use efficiency is still very low due to the poor irrigation practices (Hu et al., 2005; Wang et al., 2001). Excessive application of chemical fertilizer in China is another fear factor for long term farmland efficiency and environmental sustainability. According to the forecast of the Ministry of Agriculture, People’s Republic of China, the fertilizer consumption in the country was about 58 million tons in 2006 which accounted for 37.1% of the world’s total. During the period of 1992 and 2006, China was the highest contributor for increasing international fertilizer consumption. In arid and semiarid regions of NCP (double cropping wheat and corn areas), there is a common trends of excessive fertilization (about 600 kg ha-1) for better crop production and some recent studies (Yuan et al. 1995; Zhu and Chen, 2002; Li and Li, 2000) have shown that, much of the applied fertilizer was lost through leaching resulting to serious environmental hazards, including soil acidification, heavy metal contami-nation and greenhouse gas emission. The N fertilizer use efficiency in China is ranging from 30 to 35% compared with 45% of developed countries. The P fertilizer use efficiency in China is as low as 10 to 20%. According to the amount of fertilizer used in the field, if 10% of the applied N fertilizers and 20% of P fertilizers is reduced, the nation’s farmers could save 10.4 and 13.7 billion Yuan (1 Chinese Yuan = 0.15 USD) annually, respectively. Soils in the North China Plain areas are mostly characterized by low water-holding capacity, high evapo-transpiration and excessive leaching of the scanty rainfall, leading to poor water and fertilizer use efficiency by crops. As a result, much of the double-cropped wheat and summer corn area (approximately 20 to 50%) in north part of the NCP including Beijing, Tianjin and Hebei has now been replaced by mono-cropped spring corn area (Zhiming et al., 2007; Yu et al., 2006). Agricultural scientist and planers in the area are being confronted with the task of developing timely and viable alternative soil-water-crop management system to counteract the current downward trends in environmental degradation and agricultural productivity.The problem of inefficient use of fertilizer and irrigation water by crops is most important in semiarid and arid regions in the world and application of water-saving super absorbent polymers (SAP) in to the soil could be an effective way to increase both water and nutrient use efficiency in crops (Lentz and Sojka, 1994; Lentz et al., 1998). When polymers are incorporated with soil, it is presumed that they retain large quantities of water and nutrients, which are released as required by the plant. Thus, plant growth could be improved with limited water and nutrient supply (Gehring and Lewis, 1980). Johnson (1984) reported an increase of 171 to 402% in water retention capacity when polymers were incorporated in coarse sand. Addition of a polymer to peat decreased water stress and increased the time to wilt (Karimi et al., 2009; Gehring and Lewis, 1980). The incorporation of superabsorbent polymer with soil improved soil physical properties (El-Amir et al., 1993), enhanced seed germi-nation and emergence (Azzam, 1983), crop growth and yields (Yazdani et al., 2007) and reduced the irrigation requirement of plants (Blodgett et al., 1993; Taylor and Halfacre, 1986). The use of hydrophilic polymer materials as carrier and regulator of nutrient release was helpful in reducing undesired fertilizer losses, while sustaining vigorous plant growth (Mikkelsen, 1994).Three classes of superabsorbent polymer are commonly used and are classified as natural, semi-synthetic and synthetic polymers (Mikkelsen, 1994). Synthetic polyacry-lamide with potassium salt base manufactured by Beijing Hanlisorb Polywater hi-tech. Co. Ltd. used for this experiment is a cross-linked polymer developed to retain water and fertilizer in the agricultural and horticultural sector. Earlier, polymers were not used in the agricultural field due to their high prices. Recently, many polymer industries developed around northern China and the prices became comparatively cheaper (about 5 USD kg-1) on the other hands, excessive fertilizer consumption leads to an increase in compound (granular) fertilizer price (about 0.4 USD kg-1). Thus, the application of SAP along with reduced rate of compound fertilizer in the agricultural field has become a popular water and fertilizer saving technology for many farmers in arid and semi arid regions of northern China. Therefore, polymers can retain soil moisture and fertilizer up to 3 to 5 years after application, which could also bring some additional economic and environmental advantages. The main objective of this study was to evaluate the effectiveness of different rates of SAP against half amount of chemical fertilization for summer corn production in a drought affected field of northern China.MATERIALS AND METHODSPlant material and growth conditionThe study was conducted under field conditions in the Shoungyi country (40°13′N, 116°65′E), Beijing, northern China. The soil wasIslam et al. 4889 Table 1. Fundamental chemical properties of soil in the studied area.ItemValueUnit 0 to 15 cm 15 to 30 cmpH (H2O) 6.8 6.78Electrical conductivity 0.73 0.70 ms/cm Total nitrogen 107.8 92.6 mg/kg Available phosphorus 32.8 19.7 mg/kg Available potassium 72.6 68.9 mg/kg Organic matter 12.2 8.3 g/kgsandy loam and the fundamental chemical properties of the soil are presented in Table 1. Plots were marked out with minimal pre-planting land preparation. Treatments comprised super absorbent polymers (SAP) applied in the row mixing with fertilizer during seed sowing at low (7.5 kg ha-1), medium (11.3 kg ha-1) and high (15 kg ha-1) rate. The levels of SAP applications (low, medium and high) were determined with manufacturer’s recommendation. The control plot received only compound granular fertilizers (NPK 15:15:15) at standard rate (300 kg ha-1), whereas all treatments with SAP received half amount (150 kg ha-1) of standard rate. Jing Dan 958, a commonly grown corn variety (Zea mays L.) in northern China was used for the experiment. Treatments were arranged into a com-pletely randomized design with three replications; each treatment occupied a plot area of 3 × 8 m. Seeds were sown on 23rd June and harvested on 29th September in 2009. Standard seed rate and row spacing (60 cm) were used during seeding and irrigated once (within one week) after sowing.Phenological measurements and calculationDetermination of plant growth (plant height, leaf area, grain yield and biomass accumulation) was carried out during harvest. Relative water content (RWC) of leaves was measured on fully expanded leaves at 8 weeks after sowing (WAS). Leaves were cut and collected at midday to determine fresh weight (FW). Leaf blades were then, placed with their cut end pointing down into a falcon tube containing about 15 ml of 1 mM CaCl2. The CaCl2 was used to increase leaf cell integrity, with the aim of reducing cell lysis due to excessive rehydration. The turgid weight (TW) was then, recorded after overnight rehydration at 4°C. For dry weight (DW) deter-mination, samples were oven-dried at 70°C for 48 h. Relative water content was calculated according to Schonfeld et al. (1988) thus: RWC (%) = [(FW – DW) / (TW – DW)] × 100 (1) The (1000) grains weight was calculated from randomly sampled grains after harvest. At maturity, a sample of 4 m2 area for each plot was harvested for grain yield and biomass determination.Soil analysisSoils were sampled at the 0 to 15 cm and 15 to 30 cm soil depths from the sowing rows after harvest. Samples were air-dried and passed through 1 mm sieve. Total N was determined by Kjeldhal method (AOAC, 1990). Available P was determined by molyb-denum blue colorimetry after Bravay-1 extraction (AOAC, 1990). Available K was measured by analyzing the filtered extract on an atomic absorption spectrophotometer set on emission mode at 776 nm (AOAC, 1990). Grain quality determinationDried samples were ground and passed through a 1 mm sieve before analysis. Nitrogen content (%) was determined by the Kjeldhal method (AOAC, 1990) and crude protein (CP) content was obtained by multiplying the Kjeldahl N values by 6.25. Starch and soluble sugar contents were also determined by official AOAC method.Climatic measurementAn automatic weather station was installed in the experimental field to record daily air temperature, rainfall and relative humidity during corn growing period (Figure 1). Air temperature ranged from 12.0 to 38.1°C and mean temperature was 17.5°C. Total precipitation was 248 mm in 33 rainy days which is 112 mm lower than corn requirements (Liu et al., 2001). Relative air humidity (daily average) ranged from 31 to 89% and mean value was 68.1%.Statistical analysisAn analysis of variance was performed using the STATEVIEW (SAS Institute Inc., Cary, NC, USA) software.Treatment means were compared using the Fisher’s protected least significant differences (LSD) at the 5% level of probability.RESULTSPlant heightPlant heights were more or less increased by applying different rates of SAP and the effects are less noticed under low application of SAP, whereas it increased remarkably by 10.3 and 18.0% under medium and high application rate (Table 2).Stem diameterStem diameter increased with increasing rate of SAP (Table 2) but the value was not significant under low application level. However, under medium and high appli-cation of superabsorbent polymer, the values increased by 15.2 and 18.6%, respectively.Leaves areaLeaves area under different treatments in corn plant also4890 Afr. J. Biotechnol.Figure 1. Daily air temperature, rainfall and relative humidity during corn growing season (23rd June to 29th September, 2009).Table 2. Plant height, stem diameter, leaf area, grains per plant and 1000 grains weight of corn under different superabsorbent polymer (SAP) treatments.Treatment Plant height (cm) Stem diameter (cm) Leaf area (m2) Grains/plant 1000 grain weight (g) CK 246.1 1.907 0.459 521.1 223.8Low 259.4 2.007 0.458 510.9 241.3 Medium 271.5 2.197 0.546 569.7 249.7High 290.3 2.257 0.608 607.7 246.3Mean 266.8 2.095 0.518 552.4 240.3LSD (0.05) 20.55 0.227 0.071 42.7 15.9CK, Control; LSD, least significant difference.presented in Table 2, did not changed under low application of superabsorbent polymer but increased remarkably following SAP application at medium and high rate by 18.9 and 32.5%, respectively.Number of grains per plantThe number of grains per plant reduced marginally (2.0%) under low application of superabsorbent polymer (Table 2), whereas under medium and high application, it increased by 9.3 and 16.6%, respectively, compared with plant without SAP or control.1000 grain weightAlthough, no marked changes were noted in 1000 grain weight due to superabsorbent polymer application, seeds of corn treated with SAP were slightly heavier than thoseFigure 2. Grain yield, biomass accumulation and relative water contents (RWC) in corn at different superabsorbent polymer rates. not treated (Table 2).Dry matter yieldThe above ground biomass accumulation (AGB) increased with increasing rate of superabsorbent polymer (Figure 2). The value increased by only 10.4% with low application of SAP, while it increased significantly by 20.5 and 32.9% with medium and high application, respectively. Grain yieldFigure 2, also shows the grain yield of corn under different treatments. The application of SAP increased theIslam et al. 4891 grain yield by 11.2% under low, 18.8% under medium and 29.2% under high rate.Relative water contentThe relative water content (RWC) in plant leaves at grain feeling stage was much higher in plants with SAP (Figure 2). Although, the value increased slightly under low application of SAP, it increased remarkably by 25.8 and 31.9% under medium and high application, respectively. Soil nutrient contentTotal N contents at 0 to 15 cm depths reduced under low superabsorbent polymer application and increased slightly under medium and significantly (25.2%) under high application (Table 3). Total N content at 15 to 30 cm depth in the soil was found lower than surface level (0 to 15 cm) and values showed similar trends following different treatments.Available P contents at 0 to 15 depth reduced by 22.2% under low and 15.1% under medium superabsorbent polymer level and remain same under high SAP level (Table 3). Available P contents at 15 to 30 cm depths were also reduced by 19.0 and 9.5% under low and medium superabsorbent polymer levels, but not in a statistically significant manner.Available K contents in the soil also presented in Table 3, reduced by 16.8 and 7.6% under low and medium superabsorbent polymer at 0 to 15 cm depth and 12.6 and 4.2%, respectively at 15 to 30 cm depth. However, K contents with application of SAP at high rate more or less remain stable in both soil depths.Grain qualityCrude protein contentsCrude protein (CP) contents in the grain reduced slightly (4.4) under low application of superabsorbent polymer and remain unchanged under medium application level (Table 4). However, the value increased significantly by 8.0% under high application of SAP.Soluble sugar contentsSoluble sugar contents in the grain did not change in a statically significant manner due to SAP application (Table 4). It reduced slightly under low SAP application and increased marginally under medium and high application levels.Starch contentsStarch contents in the grain also presented in Table 4 did4892 Afr. J. Biotechnol.Table 3. Variation in total N, Available P and Available K contents in different depths of soil under various super absorbent polymer (SAP) treatments.TreatmentTotal N (mg/kg) Available P (mg/kg) Available K (mg/kg)0 to 15 cm 15 to 30 cm 0 to 15 cm 15 to 30 cm 0 to 15 cm 15 to 30 cmCK 105.2 89.9 22.23 14.73 72.30 60.38 Low 97.0 84.8 17.31 11.92 60.17 52.56 Medium 112.5 100.4 18.87 13.33 66.80 57.83 High 131.7 119.7 22.73 17.13 73.30 59.23 Mean 111.6 98.7 20.29 14.27 68.14 57.50 LSD (0.05) 19.22 12.19 3.49 3.58 12.05 10.83CK, Control; LSD, least significant difference.Table 4. Crude protein, soluble sugar and starch content in corn grain under different superabsorbent polymer(SAP) treatments.Treatment Protein (%) Soluble sugar (%) Starch (%)CK 8.68 ± 0.65 3.72 ± 0.23 65.45 ± 2.42Low 8.29 ± 0.11 3.49 ± 0.11 61.14 ± 5.57Medium 8.71 ± 0.27 3.74 ± 0.32 70.09 ± 5.68High 9.37 ± 0.21 3.87 ± 0.16 75.59 ± 4.12Mean 8.76 3.71 68.07LSD (0.05) 0.59 0.711 15.14CK, Control; LSD, least significant difference.not change remarkably following superabsorbent polymer treatments. It reduced slightly (6.6) under low SAP appli-cation and increased marginally (7.1 and 15.5%) under medium and high application levels.DISCUSSIONSuper absorbent polymers (SAP) have been used as water-retaining materials in the agricultural and horti-cultural fields (Islam et al., 2009; Johnson, 1984; Mikkelsen, 1994; Yazdani et al., 2007) because when incorporated with soil, they can retain large quantities of water and nutrients. These stored water and nutrients are released slowly as required by the plant to improve growth under limited water supply (Azzam, 1983; Huttermann et al., 1999; Yazdani et al., 2007). Our data have shown that, the applied superabsorbent polymer had a remark-able effect on corn growth (Table 2 and Figure 2), although all the treatments with SAP received only half amount of fertilizer than control plants.Application of superabsorbent polymer could be an effective way of corn cultivation in the soils characterized by low water holding capacity where, rain or irrigational water and fertilizer leached below the root zone within a short period of time, leads poor water and fertilizer use efficiency by crops (Johnson, 1984; Mikkelsen, 1994; Yazdani et al., 2007). Under this situation, excessive fertilization would not bring any progressive change in crop performance and may rather cause some negative impact on the environment. Application of superabsorbent polymer along with reduced fertilization could change the fertilization strategy in arid and semiarid regions of China. When aqueous, nutrient-containing solutions are used to hydrate a polymer, a considerable amount of nutrient enters into the polymer structure during expansion (Martin et al., 1993; Woodhouse and Johnson, 1991). Hydrophilic polymers generally contain micro pores that allow small molecules (such as NH4) to diffuse through the hydrogel, (Johnson and Veltkamp, 1985).The subsequent release of nutrient is then based on the diffusive properties of the polymer, its decomposition rate and the nature of the nutrient salt. Mikkelsen et al. (1993) found that, addition of polymer to the fertilizer solutions reduced N leaching losses from soil columns as much as 45% during the first four weeks in heavily leached conditions compared with N fertilizer alone at the same time Fescue (Festuca arundinacea L.) growth was also increased as much as 40% and tissue N accumulation increased up to 50% when fertilized with polymer compared with fertilizer alone. In a similar study Magalhaes et al.(1987) also found a remarkable reduction of NH4, P and K leaching due to the presence of the polymer.Differences in the responses of corn subjected to SAP application were evident during our observation. Although, control plot received double amount fertilizer (orconventional standard rate), corn yield increased following superabsorbent polymer application by 11.2% under low, 18.8% under medium and 29.2% under high rate with only half amount of fertilizer (Figure 2). At the same time, protein and sugar contents in the grain also increased. Low (7.5 kg ha-1) application of super-absorbent polymer might not be enough to meet water and nutrient demands of corn, because it could not bring any remarkable progress in crop performance. On the other hands, medium application (11.2 kg ha-1) can bring some remarkable change in crop performance, but both rates could not be recommended due to reduction in soil nutrient balance (especially P and K content) after harvest (Table 3). However, high application rate (15 kg ha-1) could be an optimum rate for corn cultivation under studied areas as it brings remarkable increase in yield, biomass accumulation, protein and sugar contents in the grain and also maintain proper soil nutrient balance. Previously, the use of superabsorbent polymer for the amendment of agricultural soils was considered not economical. The application of SAP at our recommen-dation (15 kg ha-1) will cost an additional 75 USD ha-1 (15 kg × 5 USD), whereas, it can save initially half the fertilizer cost or 60 USD ha-1(150 kg × 0.4 USD). Moreover, superabsorbent polymer can retain soil moisture and fertilizer up to 3 to 5 years after application; at the same time, it also increases quantity and quality of yield. Polymers are safe and non-toxic, it also reduce excessive nutrient loss from soil thereby preventing pollution of agro-ecosystem.ConclusionsDifferences in responses of corn subjected to SAP appli-cation against half amount of chemical fertilizer were evident during our observations. Although, control plot received double amount fertilizer (or conventional rate), corn yield increased following SAP application by 11.2% under low, 18.8% under medium and 29.2% under high rate with only half amount of fertilizer. Low and medium application can bring some remarkable change in corn growth performance, but both rates could not be recommended due reduction in soil nutrient balance after harvest. However, application of superabsorbent polymer at 15 kg ha-1against half amount of chemical fertilizer could result to an optimum rate of increase for corn cultivation under the studied areas as it brings remark-able increase in plant height, stem diameter, leaves area, biomass accumulation, grain yield and relative water content as well as protein and sugar contents in the grain. Also, it maintains proper soil nutrients balance after harvest. Thus, the use of superabsorbent polymer could be an effective means for corn production under the arid conditions of northern China or the areas with similar ecologies. Further research on superabsorbent polymer application should consider the duration of its effect andIslam et al. 4893 its environmental and economic advantages on the soil and plants.ACKNOWLEDGEMENTSThis research was supported by grants from the Ministry of Agriculture (No.NYHYZX07-009-2) and the Ministry of Science and Technology (No. 2006BAD15B02), People’s Republic of China. Cordial thanks are due to Mr. Xu Daiauan and the local farmers of Shoungyi country (Beijing, People’s Republic of China).REFERENCESAOAC (1990). (Official Methods of Analysis) 15th ed, Association of Official Analytical Chemists, Washington DC.Azzam RAI (1983). Polymeric conditioner gels for desert soils. Comm.Soil Sci. Plant Anal. 14: 739-760.Blodgett AM, Beattis DJ, White JW, Elliot GC (1993). Hydrophilic polymers and wetting agents affect absorption and evaporate water loss. Hort. Sci. 28: 633-635.El-Amir S, Helalia AM, Shawky ME (1993). Effects of acryhope and aquastore polymers on water regime and porosity in sandy soils.Egypt J. Soil Sci. 4: 395-404.Gehring JM, Lewis AJ (1980). Effect of polymer on wilting and moisture stress of bedding plants. J. Amer. Soc. Hort. Sci. 105: 511-513.Hu C, Delgado JA, Zhang X, Ma L (2005). Assessment of groundwater use by wheat (Triticum aestivum L.) in the Luancheng Xian region and potential implications for water conservation in the northwestern North China Plain,J. Soil Water Conserv. 60: 80-88.Huttermann A, Zommorodia M, Reise K (1999). Addition of hydrogel to soil for prolonging the survival of Pinus halepensis seedlings subjected to drought. Soil Till. Res. 50: 295-304.Islam MR, Eneji AE, Hu YG, Li J (2009). Evaluation of a water-saving superabsorbent polymer for forage oat (Avena sativa L.) production in an arid sandy soil. Proceedings of InterDrought-III conference, Shanghai, P.R. China. pp. 91-92Johnson MS, Veltkamp CJ (1985). Structure and functioning of water-storing agricultural polyacrylamides. J. Sci. Food Agric. 36: 789-793 Johnson MS (1984). The effect of gel-forming polyacrylamides on moisture storage in sandy soils. J. Sci. Food Agric. 35: 1196-1200. Karimi A, Noshadi M, Ahmadzadeh M (2009). Effects of super absorbent polymer (igeta) on crop, soil water and irrigation interval. J.Sci. Technol. Agric. Nat. Res. 12: 415-420.Lentz RD, Sojka RE (1994). Field result using polyacrylamide to manage furrow erosion and infiltration. Soil Sci. 158: 274-282.Lentz RD, Sojka RE, Robbins CW (1998). Reducing phosphorus losses from surface-irrigated fields: Emerging polyacrylamide technology. J.Environ. Qual. 27: 305-312.Li SQ, Li SX (2000). Leaching loss of nitrate from semiarid agroecosystem. Chin J. Appl. Ecol. 11: 240-242Liu CM, Yu JJ, Kendy E (2001). Groundwater exploitation and its impact on the environment in the North China Plain. Water Inter. 26: 265-272. Magalhaes JR, Wilcox GE, Rodriguez FC, Silva FLIM, Ferreira Rocha AN (1987). Plant growth and nutrient uptake in hydrophilic gel treated soil. Comm. Soil Sci. Plant Anal. 18: 1469-1478Martin CA, Ruter JM, Roberson RW, Sharp WP (1993). Element absorption and hydration potential of polyacrylamide gels. Comm.Soil Sci. Plant Anal. 24: 539-548.Mikkelsen RL, Behel AD, Williams HM (1993). Addition of gel-forming hydrophilic polymers to nitrogen fertilizer solutions. Fert. Res. 36: 55-61Mikkelsen RL (1994). Using hydrophilic polymers to control nutrient release. Fert. Res. 38: 53-59.NBSC, National Bureau of Statistics of China (1998). China Statistical Yearbook. China Stat. Press, Beijing.。
车前草对重金属污染的修复及生理响应研究
2019年 2月 Journal of Science of Teachers′College and University Feb. 2019文章编号：1007-9831（2019）02-0056-04车前草对重金属污染的修复及生理响应研究李婧1，2，刘丽杰1，2，孙丽媛1，2，娄贵成1，2，王钰天香1，2，马均鹏1，2（齐齐哈尔大学 1. 生命科学与农林学院，2. 抗性基因工程与寒地生物多样性保护黑龙江省重点实验室，黑龙江 齐齐哈尔 161006）摘要：介绍了土壤重金属污染概况，车前草对多种重金属的修复情况及自身的生理响应．结果表明，车前草对Se，Cu，Pb，Ni和Hg等富集能力较强，尤其是对Hg的富集系数达到9，接近于超富集状态．但对于Cd，Al，Cr，Mn，Zn和As的富集系数均小于1，富集能力较弱．对于多数重金属来说，在低浓度处理时，对车前草的生长特性及生理特性影响不大，但随着浓度的提高，车前草的生长会受到抑制，生理指标（如叶绿素、可溶性蛋白、丙二醛（MDA）等）发生变化，以适应高浓度的重金属污染带来的伤害．关键词：车前草；重金属；植物修复；富集能力中图分类号：Q94 文献标识码：A doi：10.3969/j.issn.1007-9831.2019.02.014Research on the rehabilitation and physiological response ofPlantago asiatica L. to heavy metal pollutionLI Jing1，2，LIU Li-jie1，2，SUN Li-yuan1，2，LOU Gui-cheng1，2，WANG Yu-tianxiang1，2，MA Jun-peng1，2（1. School of Life Science and Agriculture Forestry，2. Heilongjiang Provincial Key Laboratory of Resistance Gene Engineering and Protection ofBiodiversity in Cold Areas，Qiqihar University，Qiqihar 61006，China）Abstract：The general situation of heavy metal pollution in soil，the remediation of various heavy metals by Plantago asiatica L. and its physiological response were introduced．The results showed that Plantago asiatica L. had strong enrichment ability to Se，Cu，Pb，Ni and Hg，especially to Hg with enrichment coefficient of 9，which is close to super-enrichment state．But for Cd，Al，Cr，Mn，Zn and As，the enrichment coefficient is less than 1，and the enrichment ability was weak．For most heavy metals，the growth characteristics and physiological characteristics of Plantago asiatica L. were not affected by low concentration treatment．However，with the increase of concentration，the growth of Plantago asiatica L. would be inhibited．Physiological indicators such as chlorophyll content，soluble protein content and MDA content changed to adapt to the damage caused by high concentration of heavy metals treatment．Key words：Plantago asiatica L.；heavy metal；plant rehabilitation；enrichment ability1 土壤重金属污染概况比重大于5的金属被称为重金属，比较常见的有Cu，Pb，Cd，Fe和Al等．重金属是我国最严重的污染物之一，它不仅能随食物进入身体，还对自然环境产生不可估量的影响．土壤重金属污染是指由于工农收稿日期：2018-11-10基金项目：2018黑龙江省大学生创新创业训练项目（201810232087）作者简介：李婧（1997-），女，黑龙江齐齐哈尔人，在读本科生．E-mail：lilijing1997@通信作者：刘丽杰（1980-），女，黑龙江齐齐哈尔人，副教授，博士，从事植物生理与分子生物学研究．E-mail：liulijie2001@.业生产，人类活动以及土壤中部分有害物质的含量超过了土壤自身能够承受的范围，这些物质过量积累，土壤出现了受毒害的症状．这种环境中的重金属含量超出了正常范围，环境质量恶化，即为重金属污染[1]．目前中国存在着土壤重金属污染逐渐加重的现象，当土壤中重金属的含量超过土壤本身所能承受的限度时，将会出现土地质量下降，进而影响生物生活的环境和生物密度，严重时会危害生态环境．重金属污染来源主要有3种，即灌溉未经处理的重金属污水，随意扔未经处理的重金属废弃物及大气降尘[2]．当施用过多的各种盐类化学物组成的肥料时，土壤中的盐类化合物浓度就会升高，土壤盐溶液浓度也会增加，此时土壤的渗透压就会降低，造成植物细胞失水严重，甚至死亡，即“烧苗”．而且肥料过多也会被雨水冲刷，造成不必要的污染和浪费．未经处理的水任意排放会导致水中的氮、磷等元素大量累积，藻类植物大量生长，水中的溶氧量降低，鱼虾类死亡，污染水源使含氮化合物超标．大规模、单一、长期的使用化肥会导致土壤酸度增加，酸化的土壤会使根瘤菌死亡，固氮菌的固氮能力流失，也会对矿质元素的可利用性产生不利影响，如K，P等元素容易造成Fe，Mn，Al等元素毒害植物．土壤重金属污染修复的方式有多种[3]，主要包括物理修复、化学修复和生物修复等．生物修复一般指利用生物的生命活动来减少土壤中的有害物质，使其浓度降低或恢复到原来的水平．包括植物修复、微生物修复以及植物和微生物联合修复等．植物修复是指以植物的忍耐和超积累化学元素为基础的一种修复手段，是污染整治的重要手段之一，是目前世界范围内的研究热点．已经发现一些植物能够修复重金属的污染问题，目前对植物修复技术的研究越来越深入，以期发现更多符合条件的修复植物，减轻土壤的重金属污染．2 车前草对重金属污染的修复概况土壤为植物提供矿物质营养和有机营养，因此土壤中重金属的含量与植物中重金属的含量密不可分．植物可以修复重金属污染，主要的植物修复技术一般包括4种，即固定、吸收、过滤和挥发[4]． 车前（Plantago asiatica L.），又名车前草、车轮草等，是多年生草本植物，属于车前科．我国车前草资源比较丰富，全国各地均有分布．其具有生物量大，生长快的特点，有潜力修复土壤污染．因此，研究车前草对各种重金属的富集特征和重金属处理下的生理响应将对土壤重金属污染的治理具有重要意义． 2.1 车前草对Se的富集及生理响应用不同浓度的Se处理车前草，当浓度较低时，车前草根系和地上部分的生物量以及光合色素含量都有一定程度的升高，而高浓度Se处理会使光合色素含量和生物量都降低[5]．车前草地上部分和根系中Se的含量都会随土壤中Se浓度的升高而升高，可溶性蛋白含量以及抗氧化酶SOD，POD，CAT活性也都呈现先上升后下降的趋势．随着土壤中Se浓度的不断增加，车前草中Se含量也不断增加，当土壤中Se浓度为10，25 mg/kg时，车前草的根部和地上部分对Se的富集能力达到最高值，分别为8.49，3.27，这说明车前草对Se有一定的耐受能力，能够有效富集土壤中的Se．由此可见，车前草是富集Se量较高的一种药用植物，做适宜浓度的Se处理，既可以提高车前草的酶活性和光合作用，助其生长，还能够满足人类对富Se保健品的需求．但是高浓度的Se对植物有毒害作用，因此Se浓度在25 mg/kg较为适宜．另外，不同浓度的褪黑素处理可使车前草地上部分和根系的Se含量增加，地上部分和根系富集系数提高，在褪黑素浓度达到200 µmol/Ｌ时，其根系富集系数和地上部分富集系数达到最大值，分别为43.33，13.60，说明褪黑素可能增强了车前草对土壤中Se的耐受性，并且提高了其对Se的富集能力[6]．2.2 车前草对Cu的富集及生理响应车前草叶片对可交换态的Cu以及碳酸盐结合态的Cu具有较强的吸收能力．魏芳雪、杨樱[7-8]等对淮南某复垦区车前草重金属元素富集系数与转移系数分析发现，车前草对Cu的富集能力较强，富集系数大于1.0．车前草的生长受到Cu的明显抑制，生物量、株高和根长都随Cu浓度的增加而呈下降趋势，但Cu的浓度超过一定范围时，这种抑制作用开始逐渐减弱，当Cu的浓度为1 500 mg/kg时，抑制达到最小状态．高浓度的Cu处理使车前草根系受到明显的毒害．叶绿素含量随Cu处理浓度的增大而减少，宝贝凼矿区（BBD）车前草的Cu含量比泸州市泸县农田（LX）车前草的Cu含量高，这说明BBD车前草吸收Cu的能力大于LX车前草，车前草是一种潜在的Cu修复植物．LX车前草在不同浓度Cu处理的富集系数和转移系数都比BBD车前草低，表明BBD车前草对Cu的富集能力和转移能力强于LX车前草[9-11]．2.3 车前草对Pb的富集及生理响应细胞器和细胞壁是植物对Pb富集和解毒的重要部位，细胞壁对进入植物内的重金属有很强的束缚作用，限制其进入细胞质内部．细胞器是呼吸作用和光合作用的主要场所，其对Pb的结合能力较强，但是Pb的含量过高时，会对植物的生理功能造成不良的影响[10]1969．土壤中Pb浓度为500，1 000 mg/kg时，车前草根的Pb含量分别为对照的18.23，51.40倍，车前草地上部分Pb含量分别为对照组的3.29，10.33倍，表明车前草地上部分和根的Pb含量随土壤中Pb含量的增加而增加，根对Pb的富集能力比地上部分的富集能力强，富集系数除处理浓度为1 000 mg/kg外，其余处理下均大于1．车前草的转移系数随土壤中Pb 添加量的增加而增加，说明Pb污染促进Pb从车前草地下部分转移到地上部分[12-13]．2.4 车前草对Cd的富集及生理响应Cd不是植物生长发育的必需营养元素，但植物很容易吸收该元素，且植物体内Cd过量会使其受到伤害．研究表明，Cd2+处理浓度的增加没有对车前草的生长发育造成特别的影响，在土壤中Cd2+浓度较高时，车前草仍然能够正常生长，说明车前草可能对Cd2+具有比较强的抗性[14]．随着重金属Cd2+浓度的增加，车前草的地上部分和地下部分Cd2+含量也会不断增加，并且地下部分含量远高于地上部分，说明Cd2+是在根部进行积累，并且只有少部分转移到地上，也说明根部是车前草吸收Cd2+的主要器官，对车前草抵抗Cd2+起着非常重要的作用．随着重金属处理浓度的不断增加，转移系数出现下降的趋势，说明土壤中Cd2+含量的增加抑制了车前草将Cd2+运输到地上部分．富集系数可以反应植物对重金属富集能力的大小，当富集系数大于1时，可以认定这种植物对某种重金属有一定的富集能力，植物对重金属的吸收能力越强其富集系数就越大，而通常所指的超富集植物其富集系数会大于10．通过实验发现，车前草对Cd2+的富集系数会随着重金属处理浓度的不断增加而呈下降趋势，而且全部小于1，说明车前草不是Cd2+的富集植物．当土壤中Cd2+浓度增加时，车前草的耐性系数均比1大，说明了车前草对Cd2+胁迫处理具有较高的耐性[15]．重金属Cd2+处理后车前草的叶绿素含量和可溶性蛋白含量均随重金属浓度的增加而不断增加，SOD和POD活性则呈现出先上升后下降的趋势，MDA含量一直增加，在重金属浓度较低时上升较慢，而在高浓度重金属处理时则迅速上升．说明在低浓度Cd2+处理下保护酶系统会抑制MDA的增加，从而在逆境下保护植物的膜系统不受破坏．2.5 车前草对Ni的富集及生理响应车前草对重金属Ni具有一定的忍耐作用，用不同浓度的Ni处理车前草后发现，当Ni浓度为150 mg/kg时，车前草可以正常生长，生物量变化不大．由此可见，车前草适合Ni中等污染土壤的修复．进一步研究发现，当Ni浓度相同时，车前草的生物量与土壤中N含量正相关（P<0.01）．车前草地下部分Ni浓度与土壤中Ni 浓度正相关（P<0.01），地上部分干质量与土壤中Ni浓度负相关（P<0.01）．另外，车前草对Ni的富集程度与土壤肥力密切相关，当土壤肥力较低时，车前草对Ni的富集率较高[16]．魏芳雪等通过对淮南某复垦区不同植物重金属元素富集系数与转移系数分析表明，车前草对Ni元素的富集系数大于1，富集能力较强．车前草对重金属Ni的转移系数大于0.5，其转移能力较强[7]15．2.6 车前草对Al的富集及生理响应浓度较低的Al胁迫处理对车前草的生长影响较小，当Al胁迫浓度增加到较高水平时（2 000 mg/L），车前草植株叶片数目逐渐减少、叶面积也变小；时间较短（10 d）的高浓度Al胁迫能使车前草的抽穗数增加，而时间较长（30 d）的Al胁迫处理则抑制了穗的生长，且浓度越高这种抑制越显著．随着Al胁迫浓度的增加，生物量分配也呈现出由地下部转移到地上部的变化趋势[17]．胡雪华[18]等在研究车前草对Al胁迫生理响应时发现，低浓度Al处理对车前草的生理指标影响不显著．低浓度Al处理车前草时，对细胞质膜透性和MDA 含量的影响都不大，Al胁迫车前草30 d后，质膜透性和MDA含量与胁迫前的变化不大，说明胁迫程度较低时，对质膜透性和细胞膜脂过氧化的影响都不显著，可能对膜脂过氧化有一定的防御作用．随着Al处理浓度的增加，叶片中脯氨酸含量、可溶性蛋白质含量和可溶性糖含量均先上升后下降，细胞质膜透性和MDA 含量显著增加．用500 mg/L的Al3+处理时，车前草叶片的SOD，CAT，POD活性均明显提高．因此，在Al胁迫下，车前草能通过体内的生理保护机制来减少Al的伤害，表现出较强的耐Al特性．当用500 mg/L以上Al3+处理车前草10 d，车前草叶片中的CAT，SOD，POD活性都有提高，说明车前草对铝的反应敏感．用2 000 mg/L的Al处理车前草30 d，其仍然生存，表明车前草有很强的清除活性氧自由基的能力．但是，关于车前草对Al的富集能力以及转移能力方面的研究还未见报导．2.7 车前草对Cr，Mn，Zn，Hg和As的修复及生理响应通过对淮南某复垦区不同植物重金属元素富集系数与转移系数分析发现，车前草对Cr，Mn，Zn元素的富集系数均小于0.5，说明对这些元素的富集能力较低，对这3种元素的转移系数均在0.5~1之间，说明转移能力较弱．对As的富集系数约为0.8，转移系数为0.5，富集能力也比较差，转移能力也较弱．但车前草对Hg元素的富集系数可达到9，说明车前草对Hg元素的富集能力较强，对Hg元素的转移系数为12.93，说明其对Hg也具有很强的转移能力．3 结语综上所述，车前草对Se，Cu，Pb，Ni，Hg等重金属具有较强的富集能力，尤其是对Hg的富集系数达到9，接近于超富集状态．但对Cd，Al，Cr，Mn，Zn，As的富集系数均小于1，富集能力较弱．多数重金属处理时，浓度低时对车前草的生物量、生理指标等影响不大，但当重金属处理浓度提高后，则发生变化． 在植物修复重金属污染土壤的方法中，超富集植物富集重金属后如果不进行妥善的处理，很容易对环境造成“二次污染”，而且植物体中的重金属和土壤中的重金属相比活性更高．因此，收获后的植物要迅速处理．可以采用压缩填埋法、焚烧法、高温分解法和液相萃取法等[19]．一般来说超富集植物只能修复单一重金属，而且有些植物还会出现中毒症状等．因此，需要多关注生物学、基因工程等科学技术，培育并筛选出生物量大、生长速率快以及能修复复合污染等更好的植物．参考文献：[1] 冯致，郁继华，苏铁荣．锌对青花菜幼苗生长的影响[J]．甘肃农业大学学报，2005，19（11）：32-36[2] 杨志英，张建珠，李春苑，等．土壤重金属污染及其修复技术研究现状[J]．绿色科技，2018，22：62-64[3] 张彩凤．重金属污染土壤修复方法概述[J]．绿色科技，2018，12：64-65[4] 杨瑾，王婷婷，郭石荣．浅谈土壤重金属植物修复技术研究[J]．内蒙古林业调查设计，2018，41（6）：99-101[5] 廖人燕，黄科文，李克强．药用植物车前草的硒富集特性研究[J]．中药材，2018，41（2）：276-279[6] 廖人燕，黄科文，李克强．不同浓度褪黑素对车前草硒富集的影响[J]．中药材，2018，41（7）：1539-1542[7] 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杜博涛，李华翔，苏绘梦，等．土壤重金属污染的植物修复技术综述[J]．湖南生态科学学报，2016（2）：32-37。
常见野生食用菌重金属含量分析及安全评价
质量控制Quality Control中国果菜China Fruit &Vegetable第43卷,第12期2023年12月收稿日期:2023-06-17第一作者简介:梅婷（1987—），女，工程师，硕士，主要从事食品质量与安全工作*通信作者简介:周海泳（1983—），男，高级工程师，硕士，主要从事食品质量与安全工作常见野生食用菌重金属含量分析及安全评价梅婷1，周海泳2*（1.深圳市芯农科技有限公司，广东深圳518000；2.筠海食品（深圳）有限公司，广东深圳518000）摘要:为调查常见食用菌的重金属（铅、镉、汞和砷）含量水平，为食用菌中重金属污染状况的分析和评价提供基础数据，本研究共收集7种食用菌42个样品，按照GB 5009系列食品安全国家标准开展相应的重金属检测，根据GB 2762—2022进行评价。
结果表明，42个食用菌样品中重金属检出率为100.00%，重金属总体超标率为26.2%，超标的样品全部为野生食用菌；野生食用菌的重金属含量明显高于人工栽培食用菌，同一种重金属在不同品种的食用菌样品中含量也存在显著差异。
食用菌中羊肚菌、獐头菌、榆黄菇质量评价为三级，松茸质量等级为一级。
因此，野生食用菌中的铅、镉含量存在一定程度的超标现象，野生羊肚菌中的铅，獐头菌、榆黄菇中的镉污染程度和食品安全风险等级较高，应给予高度关注并进行风险管理。
关键词:食用菌；重金属；污染；安全指数中图分类号：S646文献标志码：A文章编号：1008-1038(2023)12-0034-05DOI：10.19590/ki.1008-1038.2023.12.006Analysis of Contamination and Safety Assessment on Heavy Metalsof Common Edible FungiMEI Ting 1,ZHOU Haiyong 2*(1.Shenzhen Core-Agricultural Co.,Ltd,Shenzhen 518000,China;2.Junhai Food (Shenzhen)Co.,Ltd,Shenzhen 518000,China)Abstract:In order to investigate the content of heavy metals and assess heavy metals contamination and healthrelated risks of common edible fungi,the content of total lead (Pb),cadmium(Cd),mercury (Hg),and arsenic (As)in edible fungi were determined ,and assessment of heavy metals contamination was made by GB 2762—2022.The detection rate of heavy metals was 100.00%in 42edible fungi samples,the exceeding standard rate of heavy metals was 26.2%,exceeding samples were all wild edible fungi samples,the content of the same heavy metal in wild edible fungi was higher than artificial planting edible fungi.There were significant differences in the content of the same heavy metal in edible fungi in different species and different areas.The quality of edible fungi samples such as morel,andcould be evaluated as grade three,while the quality of食用菌自古以来被称作山珍，是世界范围内公认的健康食品[1-2]。
电感耦合等离子体发射光谱法测定土壤中10种重金属
化学分析计量CHEMICAL ANALYSIS AND METERAGE第27卷，第3期2018年5月V ol. 27，No. 3May 201828doi ：10.3969／j.issn.1008–6145.2018.03.008电感耦合等离子体发射光谱法测定土壤中10种重金属汪丹，何恬叶，胡子文(成都理工大学材料与化学化工学院，成都 610059)摘要 建立电感耦合等离子体发射光谱法测定土壤中Ba ，Cd ，Co ，Cr ，Cu ，Mn ，Ni ，Sr ，Pb 和Zn 10种重金属的含量。
以国家标准土壤样品GSS–1，GSS–2，GSS–3为研究对象，采用硝酸、盐酸、氢氟酸和高氯酸微波消解，赶酸后加入2 mL 2%的柠檬酸溶液作为络合剂，在选定的仪器工作条件下测定，10种元素的质量浓度在0～20 μg ／mL 范围内与光谱强度存在良好的线性关系，相关系数均大于0.999，方法检出限为0.01～0.15 μg ／mL 。
测定结果的相对标准偏差为0.86%~4.82%(n =6)，10种重金属平均加标回收率为95.17%～108.67%。
该方法操作简单、稳定性好，适用于土壤中重金属含量的测定，并为络合剂在元素测定中的应用提供参考。
关键词 微波消解；络合剂；电感耦合等离子体发射光谱法；土壤；重金属中图分类号：O657.31 文献标识码：A 文章编号：1008–6145(2018)03–0028–05Determination of 10 kinds of heavy metals in soil by inductively coupled plasma emission spectrometryWANG Dan, HE Tianye, HU Ziwen(College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, China)Abstract A method for determination of 10 kinds of heavy metals including Ba, Cd, Co, Cr, Cu, Mn, Ni, Sr, Pb and Zn in soil by inductively coupled plasma emission spectrometry(ICP–OES) was established. The national standard of soil samples GSS–1, GSS–2 and GSS–3 as the research objects, using HNO 3–HCl–HClO 4–HF mixed acid system for microwave digestion. After acid being removed, 2 mL 2% citric acid solution was added as the complexing agent and measured under the operating conditions of the instrument. The mass concentration of the 10 kinds of heavy metals had good linear relationships with the spectral intensity in the range of 0–20 μg ／mL, and the correlation coefficients were all more than 0.999, the detection limits were 0.01–0.15 μg ／mL. The relative standard deviations of the results were 0.86%–4.82%(n =6), and the average recoveries were 95.17%–108.67%. This method is easy to operate and has good stability, and it is suitable for the determination of heavy metals in soil, and provides reference for the application of complexing agents in the determination of elements.Keywords microwave digestion; complexing agent; ICP–OES; soil; heavy metals随着生活水平的不断提高，人们对农产品的品质有了更高的要求，然而，农产品的品质与土壤环境质量息息相关［1］。
植物生理学：植物的抗性生理
This chapter will concern itself with environmental or abiotic factors that produce stress in plants, although biotic factors such as weeds, pathogens, and insect predation can also produce stress. In most cases, stress is measured in relation to plant survival, crop yield, growth (biomass accumulation), or the primary assimilation processes (CO2 and mineral uptake), which are related to overall growth.
干旱 盐碱化
洪涝 沙漠化
第一节 抗性生理通论
一、逆境对植物的伤害
（一）几个概念
逆境（stress） ：对植物产生伤害的环境，又称胁迫。 如：干旱、涝害、盐渍、冷害、冻害、高辐射、大气污 染、病虫害等。
抗性（hardiness）：对不良环境的适应性和抵抗力。 抗性生理（hardiness physiology）：就是研究不良 环境对植物生命活 动的影响，以及植物对不良环境的 抗御能力。
生理生化变化：形成胁迫蛋白 增加渗透调节物质 增加脱落酸含量
氧气缺乏时玉米（Zea mayL.）根皮层中通气组织的发育。
不同水稻品种籽粒Cd、Cu和Se的含量差异及其人类膳食摄取风险
不同水稻品种籽粒Cd 、Cu 和Se 的含量差异及其人类膳食摄取风险李正文1,张艳玲1,潘根兴13,李久海1,黄筱敏2,王吉方2(1.南京农业大学农业资源与生态环境研究所,南京 210095;2.江苏省昆山农业科技示范园区,昆山 215300)摘要:采用田间试验法,研究了江苏省57个水稻品种籽粒对太湖地区乌栅土中Cd 、Cu 、Se 的吸收积累.结果表明水稻籽粒的Cd 、Cu 、Se 含量的变化范围分别为01099±01039、4186±21595、01035±01007mg/kg ,指示不同水稻品种对同一土壤中Cd 、Cu 、Se 的吸收及其在籽粒中的积累存在有显著的差异.不同品种籽粒对Cu 和Cd 的吸收积累有同步的趋势,而高Se 品种显示出抑制重金属Cu 和Cd 积累的倾向.不同品种籽粒中重金属含量的差异可能影响到人类重金属食物摄取的健康风险,57个品种中92%的样品的Cd 含量超出USEPA 推荐的人类摄取的籽粒临界含量.因此,在土壤重金属污染地区,必须密切注意高Cd 、Cu 吸收积累品种的大规模栽培.而筛选高Se 低Cu 、Cd 的水稻品种进行品质育种是可能的.关键词:水稻重金属吸收;镉;铜;硒;籽粒积累;品种差异中图分类号:R99416,X503.231 文献标识码:A 文章编号:025023301(2003)0320420112基金项目:教育部重点研究项目资助(2002012)作者简介:李正文(1964～),男,湖南冷水江人,博士生,主要从事植物生物化学与环境效应研究.收稿日期:2002212211;修订日期:20032012033通讯联系人G rain Contents of Cd ,Cu and Se by 57Rice Cultivars and the Risk Sig 2nif icance for H uman Dietary UptakeLi Zhengwen 1,Zhang Yanling 1,Pan G enxing 13,Li Jiuhai 1,Huang Xiaomin 2,Wang Jifang 2(1.In 2stitute of Resource ,Ecosystem and Environment of Agriculture ,Nanjing Agricultural University ,Nanjing 210095,China ;2.Agricultural Technology Demonstration Farm ,Kunshan City ,Jiangsu Province 215300,China )Abstract :Field experiment on uptake and accumulation of Cd ,Cu and Se in grains by 57rice cultivars grown on a single Wuzhatu (a black heavy soil )in Jiangsu Province were conducted.The grain concentrations of Cd ,Cu and Se varied in the range of 01099±01039,4186±21595,01035±01007mg/kg respectively ,demonstrating remarkable inter 2species difference in heavy metal accumulation in rice grains.Cd uptake and accumulation in grains followed that of Cu by the studied cultivars.However ,high Se uptake and accumulation tended to su ppress Cu and Cd uptake and accumulation in grains.By calculation using the R f D values recommended by USEPA and WHO res pectively ,human health risk was shown to be possible from consuming the rice grains from these varieties by a Chinese diet.The Cd concentration of 92%of the varieties was found over the permissible limit recommended by USEPA.Thus ,attention must be paid to ex 2tensive cultivation of high Cd accumulation cultivars of rice in polluted rice soils.For grain accumulation of Se was usual 2ly associated with low Cu and Cd accumulation ,rice breedin g with improvement of rice Se level would be possible for production of high quality of rice.K eyw ords :heavy metal uptake by rice ;Cd ;Cu ;Se ;grain accumulation ;genotype difference 一般认为,人类摄取的重金属主要通过土壤2作物2食物途径[1].最近10年来,关于土壤环境中重金属的生物有效性研究已由有环境化学制约性转向植物制约性研究,并试图按照不同作物对不同元素的生育期全程积累特点进行估计[2].20世纪90年代以来,国际上对于重金属元素的环境标准越来越严[3].最近,提出了通过土壤2作物污染物迁移分配模型结合食物结构进行人类污染物的食物摄取的风险评价方法[4].明确不同作物及不同品种对土壤环境重金属的吸收积累的差异,对于制定农产品安全生产和保障食物安全是十分迫切的任务.有文第24卷第3期2003年5月环 境 科 学ENV IRONM EN TAL SCIENCEVol.24,No.3May ,2003献表明,不同植物无论在养分元素的吸收还是有毒污染物的吸收上都存在依植物种类和品种的差异(即生态型差异和基因型差异)[5].稻米是我国人民的主要消费食物,栽培品种众多,但它们在污染物吸收上的广泛差异还很少报道.本文收集了江苏省目前用于生产栽培的57个中稻品种,在太湖地区主要水稻土(乌栅土)上进行田间比较试验,观察其对土壤环境重金属的吸收积累的特点,为土壤2水稻系统重金属生物有效性研究和水稻食物安全标准提供依据.1 材料与方法111 材料与试验设计供试水稻品种57个,为江浙沪地区中粳稻.种子由江苏昆山市玉山镇种子站提供.试验于2000年在江苏省昆山市农业科技示范园区进行,土壤为太湖地区主要农业土壤之一的乌栅土,其耕层土壤的基本性质为:p H (H 2O )6154,CEC18181cmol/kg ,有机碳6175g/kg ,粘粒(<1μm )含量225g/kg ,Cd 、Cu 、Se 全量分别为01427、30162、01336mg/kg.试验为2次重复,各小区面积13134m 2,稻谷分别单独收获晒干.其它农事操作同常规大田生产.112 分析方法收获稻谷经风干、脱壳,用粉碎机粉碎、过60目筛,用HClO 42HNO 3消化,待测液中Cd 、Cu 和Se 含量分别用原子吸收光谱法和原子荧光光谱法测定[6].以国家标准物质G BW07603(GSV 22)为内标控制分析质量.2 结果和讨论211 不同品种籽粒中Cu 、Cd 和Se 的含量供试品种籽粒Cd 、Cu 、Se 含量的测定值的结果列于表1.可见,57个品种籽粒Cd 含量的极差达8倍,Cu 达315倍,Se 为317倍.不同品种籽粒Cd 、Cu 、Se 含量的变异系数分别为3914%、5314%和20%,说明不同的水稻品种间籽粒对Cd 、Cu 、Se 含量的积累存在着明显的基因型差异,这种差异对籽粒Cd 的影响最强,Cu 次之,Se 较小.将籽粒3种重金属元素的测定值的频率分布示于图1.3元素的籽粒含量分布均遵循正态分布规律.大多数品种籽粒Cd 含量为0107～0115mg/kg ,Cu 为315～610mg/kg ,Se 为20～45μg/kg.表1 供试57个水稻品种籽粒中Cd 、Cu 和Se 含量的变化范围/mg ・kg -1Table 1 Variation of Cu ,Cu and Se contents in grains of the 57rice cultivars/mg ・kg -1元素CdCuSe最大值(maximum )0.199(勤优56)1)7.41(秋香粳)0.056(嘉优99)最小值(minimum )0.026(镇稻5171) 2.96(HG D70)0.015(96232)算术平均值(arithmetic mean )0.099 4.860.035几何平均值(geometric mean )0.0914.4700.034中值(middle value )0.097(83001) 4.49(99283武进)0.034(HG D70)标准差(standard error )0.039 2.5950.007变异系数(coefficient of variation )/%39.453.420 1)括号内为水稻品种名图1 供试水稻品种籽粒中重金属元素含量的样本分布Fig.1 Distribution of observations of heavy metal contents in rice grains212 籽粒中重金属元素间的关系对供试的所有品种籽粒的3个被测元素含量分别进行两两对比,结果示于图2.可见,籽粒Cu 、Cd 间存在明显的正相关关系,而Se 、Cu 间却反映出反相关关系.但是,Se 、Cd 间的关系不十分明显.这说明,对同是二价阳离子的重金属来说,水稻表现出协同吸收的特点.而Se 以阴离子SeO 2-3或SeO 2-4形态被吸收,水稻对Se 的高吸收抑制了二价重金属的吸收与籽粒中的积累,这与文献上报道的P 2Cd 关系是吻合的[7].二价重金属离子被根系较多的硒酸盐络合而阻抑于根系,这可能是某些品种基因型通过高硒吸收而主动抑制重金属吸收和向籽粒转运的机制.因此,在这些供试品种中,可以选育高硒低重金属铜、镉的水稻栽培型品系.图2 供试品种籽粒的Cu 、Cd 、Se 含量的相互关系Fig.2 Relationships between the grain contents of Cu ,Cdand Se of the studied rice varieties3 讨论311 水稻籽粒的Cd 、Cu 、Se 积累及其与土壤Cd 、Cu 、Se 含量的关系积累系数可以反映一个元素在作物体内的迁移积累程度.将籽粒中任一重金属元素的浓度除以土壤中的相应元素全量即计算得到籽粒的重金属元素的积累系数(PAF 值)[4].计算表明,供试57个品种籽粒的Cd 、Cu 、Se 的PAF 值分别变动于01061～01466、01097～01242、01046～01167.说明不同的水稻品种基因型对重金属Cd 、Cu 和Se 的吸收积累强度的影响可分别差异7倍、3倍和4倍.据陈怀满[8]报道的结果,谷物中Cd 、Cu 的PAF 值范围分别介于0126～2143和0117～0162;供试57个品种籽粒Cd 和Se 的PAF 值分别比Kabata 2Pendias 报道的旱地谷物的平均值0103和0101[9]要大得多,可能意味着水稻籽粒比旱作谷物更易吸收和积累重金属Cu 、Cd.同时,比较供试品种对不同元素的平均PAF 值,从大到小为Cd >Cu >Se ,说明Cd 相对较易在水稻籽粒中积累,Cu 次之,Se 不易在籽粒中积累.Cd 向籽粒迁移的量大约占作物体总量的40%[10].312 水稻籽粒的Cd 、Cu 、Se 积累与人类食物摄取风险对照卫生部最新修订待批准的粮食和卫生标准Ξ,供试水稻各品种籽粒Cd 、Cu 和Se 的含量都没有超过Cd 限量标准012mg/kg 、Cu 限量标准10mg/kg 和Se 限量标准013mg/kg 的水平.反之,作为动物必需的Se ,大部分品种籽粒Se 含量在40μg/kg 以下,低于我国食品卫生标准.世界卫生组织规定成年人Cd 、Se 的最大允许摄入量R f D 值分别为7和5μg/(kg ・d )[11];根据我国平均食物消费结构ΞΞ,人均每年消费稻麦等谷类粮食作物206kg ,设谷类全部为大米,则成人每天消费稻米01564kg ,计算出稻米中Se 允许含量为01266mg/kg ,而Cd 则为01372mg/kg.不过,国际上Cd 的环境标准日益严格[12],USEPA 推荐的R f D 值Cd 仅为1μg/(kg ・d )[13];按此计算,若在我国饮食中消费供试水ΞΞΞ新华社北京2001年10月16日电(扬子晚报2001年10月17日A3版)中华人民共和国卫生部办公厅.关于征求对《粮食卫生标准》等4项卫生标准意见的函.2002年6月稻稻谷,则籽粒中Cd 的允许含量仅为01053mg/kg ,因而有92%的供试品种的稻米Cd 超过临界摄入值(图3),吸收积累Cd 强的品种(如勤优56等)甚至超标4倍左右.因此,供试57个水稻品种大部分存在Cd 的健康风险.也就是说,对于严格的环境标准来说,供试水稻对重金属的籽粒积累的品种差异可以带来明显不同的健康风险效应.江浙沪地区土壤Cd 污染积累较明显,应十分注意高积累品种对土壤Cd 的吸收积累现象[14,15].不过,尽管品种间Se 吸收积累差异明显,但计算表明即使食用含硒最高的品种嘉优99(Se 01056mg/kg )的稻米,成人每天的硒摄入量只达32μg ,仍低于国家营养协会推荐的成人最低日摄入量40μg [16].因此,为了提高食物链硒水平,筛选高硒水稻仍是今后品质育种的方向.图3 供试57个品种的籽粒Cd 含量[设R f D 值1μg/(kg ・d)计算]与临界摄取含量的关系Fig.3 Grain Cd concentration of the 57rice varietiescompared to the critical uptake concentration[dashed line ,calculated with the R f D1μg/(kg ・d )as recommended by USEPA 2000]4 结论苏浙沪地区57个水稻品种在同种土壤条件下对重金属Cu 、Cd 和Se 的吸收和籽粒积累存在明显的基因型差异.在大规模种植同一品种时可能对食物的Cd 摄取构成明显健康风险,尤其在土壤污染较为严重的地区需密切注意避免高Cd 积累品种的大规模种植生产.尽管品种间Se 的吸收积累差异较大,但均不足以满足食物硒供应.不同品种籽粒对Cu 和Cd 的吸收积累有同步的趋势,而高硒品种显示出抑制重金属Cu 和Cd 积累的倾向.因此,筛选高硒而低Cu 、Cd 的水稻品种进行品质育种是可能的.本研究说明在评价土壤环境重金属其生物有效性时应考虑到作物吸收积累的这种差异.在发展保障食物重金属安全的技术时,必须考虑不同品种间的差异可能带来的人类健康风险效应.参考文献:1 Dudka S et al.Accumulation of potentially toxic elements inplants and their transfer to human food chain.Journal of En 2vironment Science and Health ,1999,B34(4):681～708.2 Peijnenburg W et al.Quantification of metal bioavailabilityfor Lettuce (L act uca sative L.)in field soils.Environ.Cont.and Toxic.,2001,35:1463～1488.3 Swartjes F A.Risk 2based Assessment of Soil and Groundwa 2ter Quality in the Netherlands :Standards and RemediationUrgency.Risk Analysis ,1999,19(6):1235～1249.4 潘根兴,A C Chang ,A L Page.土壤2作物系统污染物迁移分配与食物安全的评价模型及其应用.应用生态学报,2002,13(7):584～588.5 Laurie S H ,J A Manthey.The chemistry and role of metalion chelation in plant uptake processes.In :Manthey J A ,Crowley D E ,Luster D G (eds )Biochemistry of metal mi 2cronutrients in the rhizosphere.Lewis Publishers ,Boca Ra 2ton F L ,1994.165～182.6 鲁如坤主编.土壤农业化学分析方法.北京:中国农业科技出版社,1999.205～226.7 杨志敏等.植物体内磷与重金属元素锌、镉交互作用的研究进展.植物营养与肥料学报,1999,5(4):366～376.8 郑春荣,陈怀满.重金属的复合污染.见:陈怀满主编.土壤2植物系统中的重金属污染.北京:科学出版社,1996.294～308.9 K abata 2Pendias A.Trace elements in soils and plants.3rdedition.Boca Raton.Florida ,USA :CRC Press ,2001.315.10 王新,吴燕玉.重金属在土壤2水稻系统中的行为特性.生态学杂志,1997,16(4):10～14.11 WHO Water ,Sanitation and Health ,Guidelines for DrinkingWater Quality.2nd ed.Vol 2Health Criteria and Other Sup 2porting Information.G eneva :1999.281～283.http ://www.who.int/water 2sanitation 2health/G DWQ/Summary 2tables/Sumtab.htm.12 Chang A C ,Pan G enxing ,A L Page et al.Developing hu 2man health 2related chemical guidelines for reclaimed waster and sewage sludge applications in agriculture.Report for World Health Organization ,G eneva :2002.13 USEPA ,US Environment Protection Agency.IntegratedRisk Information System.2000,List of Substances.http :///ngispgm3/iris/subst/0006.htm.14 李恋卿,潘根兴,成杰民等.估计太湖地区水稻土表层土壤10年尺度的重金属元素积累速率.环境科学,2002,23(3):119～123.15 庞金华.上海粮食中元素的含量及土壤的安全值.长江流域资源与环境,1997,6(2):149～154.16 胡秋辉.硒的土壤生态环境、生物地球化学与食物链的研究现状.农村生态环境,2000,16(4):54～57.。
花生农作物对污染土壤中重金属镉的富集研究
花生农作物对污染土壤中重金属镉的富集研究罗子锋;周峰平;高岐【摘要】Flaming atomic absorption spectrometry are used to measure the content of cadmium in soil before and after planting peanuts we also measure the cadmium content of the roots, stems, leaves, shells, seeds of the peanuts in different cadmium content soil;at last we arrive at the result of cadmium metal enrichment in different peanut parts. The ability to absorb heavy metals in different parts of the peanut has the following grades:root>leaf>stem>seed>shell. And it was positively correlated with the content of cadmium in soil. Therefore, the peanut crops have good biological repairing effects on the soil polluted by heavy metal cadmium.%采用火焰原子吸收光谱法分别测定未种植花生前和种植花生后土壤中镉的含量，以及测定在不同镉含量土壤中花生的根、茎、叶、壳、籽实的镉含量，从而得出花生不同部位对镉金属的富集情况，结果显示：花生不同部位吸收重金属镉的能力具有以下规律：根>叶>茎>壳>籽实；并与土壤中镉含量呈现明显的正相关。
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• protect the from metal stress;
• provides essential resources for hybridization breeding and
transgenic breeding.
catalyzing the catabolism of heme to yield biliverdin IXa, carbon monoxide (CO) and iron.
Reference Hua Li, Ming Jiang, Li Ling Che. (2012) BjHO-1 is involved in the detoxification of heavy metal in India mustard (Brassica juncea). Biometals. DOI: 10.1007/s10534-012-9588-9
Discussion
• The study revealed a novel effect of plant genotypes on communication between plants and rhizosphere bacteria, and offer a new way to consider for phytoremediation of heavy metal-contaminated soil.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Results
• genotypes diversify the components of organic acid.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Results • Multiple stress-responsive elements were detected in a 1099 bp promoter sequence upstream of BjHO-1 being cloned by genome walking approach. • The expression of BjHO-1::GUS was significantly induced by Zn, Cd, Hg, and Pb. revealed that transcripts of transformants were significantly increased in seedlings
魏铭
Introduction
•
•
Plant-microbe interactions play a important role in the phytoremediation
of heavy metal-contaminated soil. Two genotypes of the Silene vulgaris, which have shown tolerance to Cr, were tested.
Results • Testing with histochemical staining of H2O2 in leaves, the wild type leaves treated with Hg were stained extensively, whereas those transformed with BjHO-1 displayed relatively light staining for H2O2.
Introduction
• • Heavy Metal-resistant Gene BjHO-1
BjHO-1 has been proved involved in the detoxification of India mustard (Brassica juncea).
Previously, Heme oxygenase-1 (HO-1) is a stress-responsive gene coding for an enzyme
Hg-induced oxidative stress. This work also provides a new example for design of transgenic plants that do not accumulate or minimizing accumulation of toxic trace metals growing on heavy metalcontaminated soils.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Results
• the community structure of bacterium around root were influenced significantly by genotypes and less by Cr contamination.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.
Reference Hua Li, Ming Jiang, Li Ling Che. (2012) BjHO-1 is involved in the detoxification of heavy metal in India mustard (Brassica juncea). Biometals. DOI: 10.1007/s10534-012-9588-9
Results • The transcript abundance varied considerably in cotyledon, hypocotyl, leaf and root respectively.
Results • Treatments with Hg resulted in a time-dependent and progressively increasing expression of BjHO-1, while the expression of BjHO-1 was extremely low under normal condition.
Results • The biomass in shoots and roots are also significantly increased comparing with wild type under Hg stress.
Results • The accumulation of Hg in transformants was significantly less than wild type.
Thanks.
魏铭 13生物技术(英) 2013332860049
Discussion
The results of research above suggest that the heavy metal-inducible gene, HO-1 provides plant
resistance to Hg toxicity by improving plant dry mass, reducing Hg accumulation, and attenuating
Results
• genoptypes significantly impact the metal uptake in shoots and roots.
Reference
P. García-Gonzalo, A. E. Pradas del Real, M. C. Lobo et al. (2015) Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities. Environ Sci Pollut Res.