江浙地质高背景区土壤-水稻系统重金属迁移富集特征研究

Heavy Metal Enrichment and Migration Characteristics in Soil-Rice Systems of Farmlands with High Geological Background in Jiangsu and Zhejiang Provinces

为了解地质高背景区农田土壤的重金属富集及迁移特点,该文对2种不同地质高背景(江苏玄武岩区和浙江黑色页岩区)农田土壤及水稻籽实中元素(Cd、Cr、Cu、Ni、Pb、Zn、As)分布特征进行分析;研究2个地区土壤-水稻系统中重金属迁移富集差异及主要影响因素,并结合土壤基本理化性质和有效态重金属建立对水稻籽实中主要重金属含量的预测模型。研究结果表明,Cd是江浙地质高背景区农田土壤中暴露风险最高的重金属元素,其中重金属元素Zn、Cu、Cd的生物富集因子最高,Ni和As相对较高,Cr和Pb最低,江苏玄武岩区农田土壤中Ni的迁移能力较强而浙江黑色页岩区Cd的迁移能力较强。土壤pH、CaO和Fe_(2)O_(3)等理化性质是影响农田土壤中重金属迁移能力的关键因素。回归预测模型表明,水稻籽实中重金属累积受到pH、CEC、黏土矿物和碳酸盐矿物的显著影响,而EDTA提取的有效态重金属更容易在水稻籽实中迁移富集。

To address the problem regarding the enrichment and migration characteristics of heavy metals in farmland soils with the high geological background,the concentrations and distributions of heavy metals(Cd,Cr,Cu,Ni,Pb,Zn and As)in farmland soils and rice grains from two different areas(basalt area in Jiangsu Province and black shale area in Zhejiang Province)were analyzed;the differences in the enrichment of heavy metals and the main influencing factors for their migration in soil-rice system were discussed.In addition,a prediction model for evaluating the major heavy metals in rice grains was established by combining the physico-chemical properties of soils and the available heavy metals.As a result,the authors suggested that inter alia Cd was with the highest exposure risk in farmland soils of high geological background areas in Jiangsu and Zhejiang Provinces;and as to the biological accumulation factor,Zn,Cu and Cd were the highest,next were Ni and As,and Cr and Pb the lowest.As for the migration capacity,Ni was more active in soils from the basaltic area in Jiangsu Province and Cd behaved rather actively in soils from the black shale area in Zhejiang Province;and the physico-chemical properties such as soil pH,CaO and Fe_(2)O_(3)were the key factors affecting the migration capacity of heavy metals in farmland soils.On the other hand,the regression prediction model suggested that the accumulation of heavy metals in rice grains was remarkably influenced by pH,CEC(cation exchange capacity),clay minerals and carbonate minerals,and EDTA-extracted heavy metals were more likely to migrate and accumulate in rice grains.