广西典型高砷背景地区石漠化土壤中砷形态及相关因子研究

广西典型高砷背景地区石漠化土壤中砷形态及相关因子研究雷亚超;张学洪;叶丽丽;袁贤斌;蒋金平

【摘要】The karst landform widely distributes in Guangxi with abundant development pattems.The ecosystem in this areas is very fragile and it is easy to be destroyed and forms karst rocky desertification.The problem of heavy metals pollution is very prominent because of high values of environmental background in these areas,especially for arsenic.It also has negative impact on the production and life of the surrounding residents.In order to reveal the variation of arsenic and its influence factors in rocky desertification soils with high-heavy metal-background in Guangxi,we investigated the top soils with similar geological background in different rocky desertification grades (no rocky desertification as control,slight rocky desertification,moderate rocky desertification,intense rocky desertification) to determined the concentration and speciation of arsenic.Multi-statistics regression analysis was used to quantify the main factors influencing the arsenic speciation in rocky desertification soil.The results indicated that the content of arsenic was gradually increasing in the top soil with the aggravation of rocky desertification,but the content of arsenic in intense rocky desertification was decreased.The content of arsenic was higher in mesoslope and downslope of hills with MRD and IRD.The speciation of As in different rocky desertification soils was mainly dominated by the residual As,followed by the oxidation and the reduction As,and the lowest was water soluble.The water soluble,oxidation and reduction As showed an

decreasing trend in the top soil with the aggravation of rocky desertification.Multiple regression analysis showed that the cation exchange capacity was the main influencing factor of the water soluble state and the oxidation state of As content.pH values were the important factor for weak acid extractable and reducible As content,which had extremely significant positive correlation (P＜0.01).The total arsenic content had significant positive correlation with the residual As (P＜0.05).%广西的喀斯特地貌分布广泛,部分石漠化地区的土壤砷污染问题比较突出.为深入了解广西重金属高背景地区石漠化土壤中砷的变化特征及其影响因素,采集广西环江县地质背景相似的不同石漠化程度(无石漠化、轻度石漠化、中度石漠化、重度石漠化)的表层土样,分析土壤样品中砷含量及形态,并采用多元线性回归模型分析石漠化土壤中砷形态的主要影响因子.结果表明,随着石漠化程度的加剧,表层土壤中砷含量呈现出逐渐增加的趋势,但是在重度石漠化土壤中砷含量有所下降.石漠化土壤样品中砷含量较高的区域分布在轻度和中度石漠化的中坡和下坡.石漠化土壤中砷形态主要以残渣态为主,其次是可氧化态和可还原态,最低的是水溶态;砷的水溶态、可氧化态、可还原态在土壤中的含量随着石漠化程度的加剧呈现出逐渐减少的趋势.多元回归分析表明阳离子交换量是影响水溶态砷和可氧化态砷的主要因子,pH值是影响弱酸提取态砷和可还原态砷的主要因子,呈极显著正相关(P＜0.01),总砷含量与残渣态砷呈显著正相关(P＜0.05).

【期刊名称】《生态环境学报》

【年(卷),期】2017(026)002

【总页数】7页(P335-341)

【关键词】重金属高背景;石漠化;砷形态;影响因子

【作者】雷亚超;张学洪;叶丽丽;袁贤斌;蒋金平

【作者单位】桂林理工大学广西环境污染控制理论与技术重点实验室,广西桂林541004;桂林理工大学广西环境污染控制理论与技术重点实验室,广西桂林541004;桂林理工大学,西岩溶地区水污染控制与用水安全保障协同创新中心,广西桂林541004;桂林理工大学广西环境污染控制理论与技术重点实验室,广西桂林541004;桂林理工大学,西岩溶地区水污染控制与用水安全保障协同创新中心,广西桂林541004;桂林理工大学广西环境污染控制理论与技术重点实验室,广西桂林541004;桂林理工大学广西环境污染控制理论与技术重点实验室,广西桂林541004;桂林理工大学,西岩溶地区水污染控制与用水安全保障协同创新中心,广西桂林541004【正文语种】中文

【中图分类】X131.3

砷（As）广泛存在于环境介质和生物体中，对生物的危害作用很大（Mandal et al.，2002）。含砷农药滥用、伴砷金属矿开采及尾矿不当处置等致使环境中砷污染日益加重，其对生态环境的直接危害和对人类的间接影响已经不容忽视，污染物砷在环境中的源解析及迁移转化途径等一直是环境学研究的热点之一（王金翠等，2011）。研究认为全球有近亿人生活在遭受砷污染较为严重的地区，其生活已经受到砷污染的影响（Meharg et al.，2003；Roychowdhury et al.，2002）。砷对生物的毒害程度受到砷形态的极大影响（Xiao et al.，2012）

西南喀斯特地区是典型的生态环境脆弱带，其石漠化过程常常伴随着总有机碳的流失、土壤酸碱度及阳离子交换量等土壤理化性质的改变（Zhang et al.，2011；Hu et al.，2016）。水土流失可作为石漠化的表观特征，而在重金属背景值较高