佛山市某工业区周边蔬菜地土壤重金属含量与评价

Heavy Metals Concentrations and Evaluation in Soils Around an Industrial Area in Foshan

采集并分析测试佛山市某工业区周边蔬菜地土壤,研究土壤Zn、Cu、Pb和Cd的含量和分布特征,按照国家土壤环境质量二级标准对其现状进行评价;并采用连续提取的方法分析了表层土壤Zn、Cu、Pb和Cd的化学形态分布。结果表明,研究区域20%的土壤样品受到重金属轻度污染,污染因子主要为Cd。土壤中Zn和Cu以残渣态所占比例最高,Pb和Cd分别以铁锰氧化物结合态和酸可提取态所占的比例最高,Zn、Cu、Pb和Cd非残渣态所占比例随着全量的增加而增加,Zn、Cu、Pb和Cd迁移能力依次为Cd>Zn>Cu>Pb。人类活动已导致该工业区周边农业土壤中Zn、Cu、Pb和Cd的明显积累,且土壤重金属明显向深层迁移。

Soil samples were collected from vegetable fields around an industrial area in Foshan, located in the Pearl River Delta in south China. The concentration of Zn, Cu, Pb and Cd and their distribution in soil profiles were studied. Their pollution status were evaluated according to class 11 of soil environment quality standard of China, and chemical speciation of Zn, Cu, Pb and Cd in surface soils were analyzed by using modified BCR sequential extraction procedure. The results indicated that 20% of soil samples were slightly polluted and Cd was the main contributor. The greatest proportion of Zn and Cu in soils was the residual fraction, Pb was the Fe-Mn oxide fraction, and Cd was the HOAc extractable fraction. The percentage of non-residual fractions for Zn, Cu, Pb and Cd increased with their total concentrations respectively. The order of mobility for Zn, Cu, Pb and Cd in soils was Cd〉Zn〉Cu〉Pb. Anthropogenic activities had led to the accumulation of Zn, Cu, Pb and Cd in agricultural soils, and these heavy metals significantly moved to the deep horizons. It is imperative to monitor and evaluate the effect of heavy metals in soils around industrial areas on agricultural product and water quality, and take measures to remediate polluted soils.