金昌市郊农田土壤Cu,Zn,Ni形态分布特征与生物有效性评价

通过野外调查和室内测试分析,研究了金昌市郊农田土壤重金属Cu,Zn和Ni的形态特征,并以麦粒中重金属含量为重点进行了Cu,Zn和Ni的生物有效性评价.结果表明,研究区域土壤重金属Cu和Ni污染严重;Cu的主要存在形态为有机结合态,Zn的主要存在形态为残渣态,而Ni的主要存在形态为潜在可利用态;三种元素的生物有效性大小顺序为NiZnCu.对麦粒中重金属健康风险进行评价反映出麦粒中Ni含量对人体健康风险较大,而Cu和Zn对人体健康风险较小.逐步回归分析结果表明,农田土壤中Cu可交换态和碳酸盐结合态对麦粒中Cu含量贡献最大,而对麦粒吸收Zn和Ni贡献最大的形态分别为Zn的碳酸盐结合态和Ni的可交换态、碳酸盐结合态、铁锰氧化态和有机结合态.土壤重金属Cu,Zn和Ni各形态分配系数较总量和各形态含量更适合表征本研究区域土壤重金属的生物有效性.

SPECIATION AND BIOAVAILABILITY ASSESSMENT OF Cu, Zn AND Ni IN ARGRICULTURAL SOILS FROM JINCHANG, GANSU, CHINA

Speaiation of Cu, Zn and Ni in argricultural soils from Jinchang City were analyzed, and their bioavailability was evaluated by placing an emphasis on the concentration of Cu, Zn and Ni in wheat seeds from the study area.The study area was severely contaminated by Cu and Ni.Cu existed mainly in organic matter-bound fraction and Zn existed mainly in residual fraction while Ni existed in potentially available form.The bioavailability of Cu, Zn and Ni was in the order of Ni > Zn > Cu.The health risk assessments of Cu, Zn and Ni in wheat seeds showed that the concentrations of Ni posed greater risk to human health, while those of Cu and Zn were small.The results of stepwise regression analysis showed that Cu of exchangeable form and carbonate-bound form, Zn of carbonate-bound form and Ni of exchangeable form, carbonate-bound form, Fe-Mn oxides bound form and organic matter-bound form made the most contributions to the contents of Cu, Zn and Ni in wheat seeds, respectively.The distribution coefficients of fractionation of Cu, Zn and Ni are more preferable than the total concentrations and the contents of fractionation of Cu, Zn and Ni to evaluate their bioavailability in this study area.