大型冶炼厂重金属环境污染特征及其生态效应

对湖北某大型冶炼厂周边的土壤-水-水体底泥-农作物体系进行了系统研究.结果表明,水稻土中重金属含量普遍高于旱地土,均表现为耕作层显著地高于深层.其中,Cd含量为国标三级土壤阈值的8～26倍.Cu、Pb、Cr、Ni、Zn在大多数样品中不超标,但远高于对照区.耕作层中重金属的可还原态、可氧化态、残渣态分量之和大大高于弱酸提取态,而可还原态和可氧化态分量之和则远高于残渣态.深层的弱酸提取态含量远高于其余3态之和,与已有的研究结果不同.该区域生长的蔬菜呈现Cd、Pb复合污染,糙米中Cd含量超标.作物的重金属污染与元素的形态分布密切相关,其中弱酸提取态分量愈高,作物愈易受污染.

The environmental pollution character and its ecological effect of a large scale smelter

The system studies on soil, water, water body sediment, farm crop system in an area near certain large smelter in Hubei revealed that the content of heavy metals element in paddyfield soil was generally greater than those in dry land soil, all indicating the farming layer was markedly higher than the deep layer, in which the Cd content was 8~26 times of the national third grade soil limited value. Cu, Pb, Cr, Ni, Zn in most of the samples did not exceed the standard, but far higher than the contrast area. On the form of element, the sum of reducible, oxidisable and residual form weight of heavy metal in the farming layer were far higher than the weak acid extractive form, while the sum of reducible + oxidisable form weights was far higher than the residual form. Contrarily, the content of the weak acid extractive form of the deep layer was far higher than the sum of the remaining three forms, these characters were utterly different from those existing studied results. The Cd, Pb compound pollution of vegetables created from the smelter, the content of Cd from brown rice exceeded the limited values. The heavy metal pollution of crops was closely related to the form distribution of element, in which the higher the weak acidic extractive weight, the easier the pollution of crops.