作　　者： ; (周永章）; (李兴远）; (莫莉萍）;

机构地区： 中山大学

出　　处： 《环境科学与技术》 2017年第12期256-266,共11页

摘　　要： 农田土壤重金属污染不利于农产品质量以及人群健康,土壤重金属的生物可利用性揭示了重金属在土壤-农作物间的迁移信息,该文以广东省顺德市农田土壤为研究对象,通过分析土壤-蔬菜系统的重金属含量与化学形态,并利用相关性分析和聚类分析对土壤-蔬菜系统的重金属生物可利用性及迁移系数进行研究。结果表明:研究区As、Cu、Hg、Mn、Ni、Pb的平均含量均大于广东省背景值的2倍,尤其是Hg,86.2%超过国家农田土壤环境质量二级标准,而蔬菜重金属含量大多数低于卫生部颁布的最新食品卫生标准。土壤重金属可利用态含量表现为:Mn>Cu>Pb>Hg>Ni>As,表明Mn、Cu、Pb和Hg具有更强的活性,同时,土壤属性(pH值和OM值)对重金属的生物可利用性和环境毒性具有影响意义。相比于土壤重金属全量,土壤中重金属的生物可利用态与蔬菜中重金属含量之间具有更显著的相关性,表明土壤重金属可利用态较全量更适合表征重金属对环境的毒性效应。基于重金属可利用态的土壤-蔬菜迁移系数(TF_(avail))表现为:Hg>As>Ni≥Mn≥Cu≥Pb,表明可利用态Hg、As和Ni更容易被蔬菜吸收,并且随着土壤重金属可利用态含量的升高,重金属的迁移富集程度呈幂函数式降低,这可能是缘于植物生理学自我保护机制,使蔬菜对重金属的吸收富集量保持在可控制范围内。 Accumulation of the toxic metals in agricultural soils is of concern on the quality of food stuffs and human health through the food chain. It is the bioavailability of heavy metals that determine the mobilization ability of the heavy metals in soil-to-crop systems. To determine the bioavailability and transfer factor of heavy metals in soil-to-crop system, surface soil and corresponding vegetables samples were collected from the typical agricultural fields of Shunde, in the rapid urbanized Guangdong Province, South China. Both soil and vegetables were analyzed for total As, Cu, Hg, Mn, Ni and Pb. The physi-co-chemical properties and chemical speciations of the metals in the soils extracted by sequential extraction were also exam-ined. The concentrations of all mentioned metals in soils were two times more than the background values of Guangdong Province, and 86.2 percent of Hg samples exceeded the maximum permissible levels established by Chinese Environmental Protection Agency. The concentrations of mentioned metals in vegetables were mainly within the food hygiene standards es-tablished by the Ministry of Health of the People＇s Republic of China. Higher correlation was found between the metal bioac-cumulation in vegetables and metal available fraction in soil with respect to between the total metal concentration in soil andthat in vegetables. That is high heavy metals concentrations in the available fraction can easily enter into the crops. The order of TFtotaland TF（avail）values from soil to vegetables was Hg Cu Mn ≥ Ni Pb ≥ As and Hg As Ni ≥Mn≥ Cu ≥ Pb,respectively in Shunde. The soil-to-vegetables transfer factors relative to TF（avail）values decrease with increasing concentration of available fraction in the soils which were consistent with the exponential equation（y=a·x-b）, indicating that the metal uptake by vegetables is not seriously affected by soil pollution, this may be due to the plant resistance mechanism protecting a low risk for food chain transfer. These results could pr

关 键 词： 生物可利用性 迁移系数 重金属 化学形态 农田土壤 土壤 农作物系统

领　　域： [环境科学与工程—环境工程]