Seasonal and spatial distribution of nonylphenol in Lanzhou Reach of Yellow River

Seasonal and spatial distribution of nonylphenol in Lanzhou Reachof Yellow River in ChinaJian Xu,Ping Wang,Weifeng Guo,Junxing Dong,Lei Wang,Shugui Dai*College of Environmental Science and Engineering,Nankai University,94Weijin Road,Nankai District,Tianjin 300071,PR ChinaReceived 7June 2005;received in revised form 13April 2006;accepted 13April 2006Available online 9June 2006AbstractNonylphenol (NP)is known as an endocrine disruptor and consequently has drawn much environmental concern.This study focused on seasonal variation and spatial distribution of NP in various matrices including water,suspended particles,and sediment taken from Lanzhou Reach of Yellow River in China.NP was measured in July and November in 2004.Concentrations of NP in water ranged from 34.2to 599.0ng/l,in suspended particles from 49.6to 2835.2ng/g dry wt,and in sediment from 38.4to 863.0ng/g dry wt.In terms of most water and suspended particles samples,concentrations were higher in warmer seasons than in colder seasons.Good linear corre-lations (R 2=0.90in July,R 2=0.97in November)were obtained for NP concentrations between water and suspended particles.In terms of sediment samples,concentrations were higher in November than in July,probably due to greater deposition of suspended particles.Reasonable linear correlations (R 2=0.60in July,R 2=0.79in November)were obtained for NP concentrations between water and sediment.Ó2006Elsevier Ltd.All rights reserved.Keywords:Alkylphenols;Nonylphenol;Endocrine disruptors;Yellow River;Distribution1.IntroductionAlkylphenol polyethoxylates (APEs)are one of the most widely used classes of surfactants.They have been used as additives in industrial detergents,pesticides,herbicides,paints,and cosmetics (Ahel et al.,1994).Although APEs are less toxic to human and organisms,the degradation metabolites,such as nonylphenol and octylphenol,are more toxic than the parent substances and possess the abil-ity to mimic natural hormones by interacting with the estrogen receptor (Ying et al.,2002).Due to persistence in the environment,nonylphenol is bioconcentrated in organisms.High levels of nonylphenol have been found in some seafood and fish caught in Italian coast and Japa-nese rivers,respectively (Ferrara et al.,2001;Tsuda et al.,2001).And even at low concentrations,nonylphenol has adverse effect on fish hormone system (Yadetie and Male,2002).Numerous estrogenic experimental results indicate that alkylphenols especially nonylphenols could cause neg-ative health effects in both humans and wildlife through disruption of the endocrine systems (Harries et al.,1997;Ying et al.,2002).So most countries have banned the usage of alkylphenol ethoxylates surfactants,and the production of them is decreasing gradually (Renner,1997;Isobe et al.,2001).In China,production of nonylphenol polyethoxy-lates (NPnEO)is about 50000tons per year,and most of them enter into the aquatic environment.High concentra-tions of nonylphenol were found in several rivers,in tap water,and in aquatic organisms.For example,Shao et al.(2002)reported that nonylphenol concentrations ran-ged from 0.02to 6.85l g/l in the aquatic environment in Chongqing Valley of Yangtze River and Jialing River in China,and after treatment in waterworks,nonylphenol concentrations in tap water was in a range from under detected limit to 2.73l g/l.Jin et al.(2004a)found that mean concentrations of nonylphenol polyethoxylates in muscle of Carassius auratus from Tianjin section of the0045-6535/$-see front matter Ó2006Elsevier Ltd.All rights reserved.doi:10.1016/j.chemosphere.2006.04.042*Corresponding author.Tel./fax:+862223504821.E-mail address:sgdai@ (S.Dai)./locate/chemosphereChemosphere 65(2006)1445–1451waste water discharge river of Beijing ranged from40to 680ng/g wet weight,and nonylphenol ranged from30to 1510ng/g wet weight.The nonylphenol pollution is draw-ing much more attention in China.Yellow River,which is called Mother River of China,is the second largest river in China and one of the largest rivers in the world.Itflows across9provinces in north China,from west to east,with mainstream5464km long, drainage area795thousand km2,and average sand content 2.83kg/m3.It is the very important water resource for industry,agriculture and people’s living.But with the growth of economy and urbanization,more and more wastes are discharged into the river,and types and amounts of pollutants increase as well.The Lanzhou Reach belongs to upper reaches of Yellow River.Dense wastes discharge along the river in Lanzhou Reach makes the pollution very serious,which will affect the water use in downstream reaches.Among those pollutants,nonylphenol has been getting increasing attention.In order to evaluate the contamination levels of nonyl-phenols in various sample matrices from Lanzhou Reach of Yellow River,and understand their distribution and behavioral characteristics,nonylphenol was determined from water,suspended particle and sediment samples in different seasons in this study.The information obtained should be helpful for pollution control and remediating the river environment.2.Materials and methods2.1.Instruments and chemicalsA Waters1525HPLC,Waters2475fluorescence detec-tor,and Waters Amino column(l Bondapak 3.9mm i.d.·300mm·5l m)were employed in the study.Waters Oasis TM HLB cartridges were used as solid phase extraction materials.Nonylphenol(technical grade)was purchased from Tokyo Chemical Synthesis Ind.Co.Ltd.,Japan. Methanol and hexane were HPLC grade,and dichloro-methane was analytical grade.Florisil was activated at 130°C for16h before use.Ultrapure water was obtained using a Millipore Ultra-pure Water System(USA).2.2.Sampling sites and sample collectionTwelve sampling sites were selected along the river in Lanzhou Reach,as shown in Fig.1.Among them,site R1was located in upstream,where there were no indus-tries.From site R2to R9,there were many industrial and municipal wastes discharging points along the river.R12 was the endpoint of our study,which was about20km away from R9,representing NP concentrations after a per-iod of self-purification in river water.Water,suspended particle and sediment samples were collected in July and November2004,respectively.Some properties ofriverFig.1.Sampling sites of the Lanzhou Reach of Yellow River.1446J.Xu et al./Chemosphere65(2006)1445–1451water in July and November are listed in Table1.One liter offiltered water sample(0.45l m)was collected in1l glass bottle with Teflon lined cap.It was added with1%of form-aldehyde and stored at4°C until pretreatment.Thefiltered suspended particles were wrapped with aluminum foil and stored in a glass bottle atÀ20°C until analyzed.The sur-face sediment(0–20cm)samples were collected in glass bottles with Teflon lined caps and stored at about À20°C until analysis.2.3.Extraction and analysisWater samples were extracted with a solid phase extrac-tion(SPE)method.One liter of water sample was passed through a SPE cartridge at aflow rate of10ml/min,which was pre-conditioned with1ml distilled water and1ml methanol.The cartridge was rinsed with2ml of metha-nol/water(5:95,v/v),and then eluted with5ml of dichlo-romethane.The effluent was rotary evaporated to nearly dryness,then redissolved in1ml of n-hexane for HPLC analysis.Suspended particle and sediment samples were Soxhlet-extracted with dichloromethane for24h.The obtained extract was concentrated to1ml under a gentle N2stream,and purified by passing through a25·1.0cm i.d.glass clean-up column containing5g of hexane-rinsed Florisil and1g of anhydrous sodium sulfate.The column was washed with50ml of hexane,eluted with80ml of ethyl ether and hexane(1:9)for NP.The eluate was rotary-vacuum evaporated nearly to dryness at40°C, transferred to a graduated tube(rinsing theflask with methanol)and adjusted to1.0ml under a stream of nitro-gen,then analyzed by HPLC.Total organic carbon(TOC) contents of sediments were measured by oxidation method (Institute of Soil Science,1978).Mixtures of n-hexane/isopropanol(98/2,v/v)and iso-propanol/water(98/2,v/v),named solvents A and B, respectively,were used as mobile phase for HPLC analysis. Gradient elution was carried out with a linear program from95%A and5%B to80%A and20%B in10min with aflow rate of1.0ml/min.Excitation and emission wave-lengths of thefluorescence detector were233and302nm, respectively.Injection volume was20l l.2.4.Quality assurance and method validationThe instruments were calibrated daily with calibration standards,and the relative percent difference between the five-point calibration and the daily calibrations were <20%for the analyte.Recovery tests were performed by adding0.5ml of the standard solution(10l g/ml)to 1000ml deionized water and5g of sediment(blank con-trol,with NP level below detection limits),respectively. Experiments were performed6times to determine the pre-cision.The recoveries by the proposed method were81.3–85.8%for water sample,and86.6–89.4%for sediment and suspended particle samples.Good reproducibility of determination was obtained with RSD values of 3.8–9.2%.The method detection limits,10ng/g for NP,were evaluated by a signal-to-noise of3.Fig.2gives HPLC chromatograms of standard NP(1l g/ml)and recovered NP from Yellow River’sediment.3.Results and discussion3.1.Spatial distribution of nonylphenolIn July2004,sediment samples were collected in Yellow River,Lanzhou Reach,from upstream to downstream as indicated in Fig.1.The results are shown in Fig.3.NP con-centrations of the riverine sediment samples ranged from 38.4to86.3ng/g dry wt.Levels of nonlyphenol in down-stream sediment samples(R5–R12)were higher than in upstream sediment samples(R1–R4).Two high concentra-tions appeared at site R5and R7.This is correlated with characteristics of wastewater discharged from pollution sources along the river.Yellow Riverflows through Lanz-hou city.The section from site R1to R4is upstream of the city.Site R5is located in the center of the city,and the sec-tion from R6to R12is downstream of Lanzhou city. Although site R1is the start point of our study,without any industrial pollution sources here,NP levels were quite high.This may be due to the pollution contribution from an upstream branch river,Huangshui River in Qinghai Province,which is seriously polluted by domestic activities. From site R2to R4,there are some industrial and munici-pal pollution sources discharging wastewater into the river. At site R5there is a big wastewater discharge stream con-sisting of municipal and industrial wastewater.The waste-water discharge pipeline from Lanzhou oil refinery located at site R7is the biggest discharge stream in Lanzhou city. High concentrations in downstream sediments might be due to discharge of effluents containing large amount of sewage and industrial wastewater from Lanzhou city.The correlation between TOC and NP concentrations is very useful to understand the spatial distribution of NP in rivers.TOC data of sediments were determined for sediments samples in July and November respectively.Fig.4shows the relationship between TOC values and NP concentrations in sediments along the river,and good correlations for July (R2=0.59)and November(R2=0.63)are observed.From Fig.3it could be seen that concentration of NP at site R12did not decrease.After about a20km long dis-tance transport from site R11to R12,its concentration had a little increase in sediment,from54.8to58.4ng/g dry wt,suggesting that NP was quite stable in river waterTable1Some properties of river water in2004Average water temperature,°C Averagesuspendedparticlecontent,g/lpH AverageDO,mg/lAverageflux,m3/sJuly190.4538.65 6.30877November100.2918.408.681120J.Xu et al./Chemosphere65(2006)1445–14511447environment.In aquatic environment,nonylphenol polyethoxylates are rapidly degraded to nonylphenol by biodegradation and photodegradation mechanism,with half-lives from 3to 5days,while half-life of NP was about 2to 3months (Ying et al.,2002;Li and Li,2003).NP could be transported a long way by river flow.3.2.Seasonal distribution and relationship of nonylphenol in water systemConcentrations of NP in the sample matrices are listed in Table 2.Concentration levels of NP in water decreased with decreasing water temperature.Li et al.(2004a)reported the similar trend in Han River in Korea,suggest-ing the activity of microorganism in the riverine system might play a role in the levels of NP.Alkylphenol polyeth-oxylates have rapidly degraded into NP and shortened alkylphenol ethoxylates at high temperature,while the deg-radation rate becomes very slow at low temperature (Tan-ghe et al.,1998;Staples et al.,1999).NP concentrations in July ranged from 34.2to 599ng/l,and in November ranged from 41.5to 376.3ng/l in water.NP is a hydrophobic compound,with log K ow value of 4.48(Ying et al.,2002).It is readily adsorbed onsurfacesFig.2.HPLC chromatograms of the standard and recovered NP from Yellow River sediment.1448J.Xu et al./Chemosphere 65(2006)1445–1451of suspended particles and sediment in water environments.Table 2shows concentrations of NP in suspended particles ranged from 50.1to 2467.8ng/g dry wt in July,and from 49.6to 2835.2ng/g dry wt in November.In sediment NPconcentrations ranged from 41.3to 86.3ng/g dry wt in July,and from 38.9to 863.0ng/g dry wt in November.In general,NP concentrations in most suspended particles samples were higher in warmer season than in colder sea-son,while in terms of sediment samples,concentrations were higher in November than in July.This may be due to the average suspended particle contents in Lanzhou Reach of Yellow River.The average particle contents were 0.453g/l in July and 0.291g/l in November,respectively (Table 1).Deposition of suspended particles in the river may cause the increasing concentration in sediment.The difference of NP concentrations in July and November can also be seen from a simple numerical ratio of concen-trations by station locations for each of the sample ing data in Table 2we calculated ratios for the concen-trations of nonylphenol in July divided by November sep-arately for each matrix and sampling site.It turned out that 9of 12water ratios were >1and 9of 12values for sus-pended particles were >1,while only 1of 12is >1for sediment.Spatial variations of the concentration of NP in three sample matrices were similar.All sites had similar concen-tration ratios of NP between the sediment or suspended particle and water.Such similarities are shown in termsTable 2Concentrations of NP in water,suspended particles and sediment from Yellow River,Lanzhou Reach in 2004SiteWater (ng/l)Suspended particles (ng/g dry wt)Sediment (ng/g dry wt)JulyNovember July November July November R165.417381.4899.342.973.5R291.248.6121.3303.550.4191.5R379.356.389.369.344.569.9R473.441.550.149.641.338.9R5279.3113.41374.1519.386.3103.6R6108.386.2298.6192.053.264.4R7599.0376.32467.82835.283.1863.0R876.976.6378.4168.042.561.2R975.256.2335.6175.762.3186.0R1071.347.8636.4224.154.054.6R1175.479.5702.0235.354.871.2R1234.261.976.180.958.482.4All NP data were conducted on triplicate samples,with standard deviation within 5%.J.Xu et al./Chemosphere 65(2006)1445–14511449of the correlation(R2)of the NP concentrations between sediment or suspended particles and water samples in Fig.5.The values of R2for suspended particles to water were0.90and0.97in July and November,respectively. R2for sediment to water were0.60and0.79in July and November,respectively.parison with other places in the worldBesides Shao et al.(2002)reported the NP concentra-tions in the aquatic environment in Chongqing Valley ofYangtze River and Jialing River,research has been done in China(Jin et al.,2004b).Lanzhou Reach of Yellow River was moderately polluted by NP compared with pollution levels of NP in other areas of the world.Tables 3and4give the concentrations of NP in surface waters and in sediments in some countries and areas,as reviewed by Ying et al.(2002).4.ConclusionIn the three sample matrices of water,suspended parti-cles and sediment,NP levels showed seasonal and spatial variation.Temperature was the key factor affecting the sea-sonal variation of NP in water and suspended particles. The distribution and characteristics of pollution sources along the river affected the spatial variation of NP in Yellow River,Lanzhou Reach.Strong correlations bet-ween NP concentrations in water and suspended particles or sediment were observed.Although measured concentrations of NP in water,sus-pended particles and sediment are not high,some individ-ual values may exceed reported toxic levels.For example, the lowest effective concentration of NP in shrimp for sub-acute toxicity is26ng/g dry wt in sediment(Li et al.,2004). Levels of NP in suspended particle and in sediment might be potentially hazardous to organisms in the river.Because Yellow River has a characteristic of high sand content,fur-ther study should be made to investigate the environmental behavior and impact of suspended particles in the river.Table3Concentration of NP in surface watersLocation NP concentration(l g/l) Canada<LODÀ0.92UK<0.03–53Switzerland<LODÀ0.48Spain<LODÀ644Japan<LODÀ3.0USA<0.11–0.64Germany0.0067–0.134Taiwan 1.8–10Korea a0.017–1.533China(Yellow River)0.034–0.599a Li et al.,2004b.Table4Concentration of NP in sedimentsLocation NP concentration(l g/kg) UK<0.1–15USA<2.9–2960Canada0.1–72Japan30–13000Korea a10.4–5054.1China(Yellow River)38.4–863.0a Li et al.,2004b.1450J.Xu et al./Chemosphere65(2006)1445–1451AcknowledgementThis study is jointly funded by‘National Science Foun-dation of China–Yellow River Conservancy Commission’with Grant No.50239060.ReferencesAhel,M.,Giger,W.,Koch,M.,1994.Behavior of alkylphenol polyeth-oxylate surfactants in the aquatic environment.1.Occurrence and transformation in sewage treatment.Water Res.28,1131–1142. 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