小清河污灌区农田土壤重金属形态分析及风险评价  

Fraction distribution and ecological risk assessment of soil heavy metals in the farmland soil from the sewage irrigated area of Xiaoqing River

作　　者：杨新明 庄涛 韩磊 刘高风 YANG Xinming;ZHUANG Tao;HAN Lei;LIU Gaofeng(Institute of Soil,Environmental Research Institute of Jinan,Ji'nan,250101,China)

机构地区：[1]济南市环境研究院土壤研究所,济南250101

出　　处：《环境化学》2019年第3期644-652,共9页Environmental Chemistry

基　　金：山东省自然科学基金(ZR2016DB19)资助~~

摘　　要：选取小清河污灌区农田为研究区域,采集31个表层土壤样品,测定了土壤重金属(Cd、Cr、Cu、Zn、Ni、As和Pb)含量,采用改进的BCR顺序提取法对土壤重金属的形态进行分析,并基于潜在生态风险指数法和风险编码法(RAC)对土壤中重金属的生态风险进行评估.结果表明,小清河污灌区土壤中Cd、Cr、Cu、Zn、Ni、As、Pb平均含量分别是0.37、51.61、32.62、68.49、34.12、40.77、32.26 mg·kg^(-1).土壤中Cr、Zn、Ni、As以残渣态占绝对优势,Cu以残渣态和可氧化态为主,Pb则以可还原态为主,而Cd表现出了形态多样的分布特征;重金属生物活性大小排序为:Cd> Pb> Cu> Zn> As> Ni> Cr;潜在生态风险指数法的评价结果表明,Cd处于中度-很强风险水平,As处于轻微-中度风险水平,其他重金属为轻微风险水平.综合潜在生态风险指数RI值在51.23—199.33,处于轻微-中等风险水平,Cd、As是土壤重金属的主要风险源,其对综合潜在生态风险指数的贡献率分别为57%、31%;RAC评价结果表明,土壤Cd处于中度-高风险水平,Zn处于低-中度风险水平,其他重金属为低风险水平.In the sewage irrigated area of Xiaoqing River, 31 surface soil samples were collected to determine the total concentrations of heavy metals (Cd, Cr, Cu, Zn, Ni, As, Pb). A modified BCR sequential extraction procedure was used to identify the fraction distribution of heavy metals in the soil. The average concentrations of Cd, Cr, Cu, Zn, Ni, As, Pb in the soil were 0.37, 51.61, 32.62, 68.49, 34.12, 40.77, 32.26 mg·kg^-1 in this area. The ecological risk of heavy metals was assessed by using two methods including potential ecological risk index and risk assessment code (RAC). The results showed that Cr, Zn, Ni and As were dominated by the residual fractions, Cu was mainly composed of the residual and oxidizable fractions, and mass fractions of Pb existed mainly in the reducible fractions, while Cd was controlled by various fractions. The bioavailability of heavy metals was in the descending order of Cd > Pb > Cu > Zn > As > Ni > Cr. Based on the calculation of the potential ecological risk index, it was found that Cd was at the level of medium to high risk, As was at the level of low to medium risk, and other metals were of low risk to the environment. The integrate potential ecological risk index (RI) of the heavy metals was in the range of 51.23-199.33, which was at low to medium potential risk level. Particularly, it was found that both Cd and As were the major risk resources to the environment, since the contribution rates of Cd and As were 57% and 31%, respectively. Finally, the results of the RAC showed that Cd was at a moderate to high risk level, Zn was at a low to medium ecological risk level, and other metals presented low level of risk to the environment.

关 键 词：小清河 污灌区 重金属 形态分析 风险评价 

分 类 号：X53[环境科学与工程—环境工程]