土壤和沉积物中重金属积累及其Pb、S同位素示踪

对榨子厂附近一个废弃多年的古老土法炼锌点土壤和沉积物中重金属的积累及污染程度进行了研究。研究区土壤、沉积物样品中Pb、Zn、Cd含量已大大高于该地区的背景值,zn的积累明显大于Pb的积累程度。相关分析表明,土壤和沉积物中Fe2O3对重金属有强烈的固定作用。沉积物和土壤中有很高的综合污染指数,显示出重金属的污染程度很高。化学形态分析表明重金属以碳酸盐结合态、残渣态和铁锰氧化物结合态为主,有效态所占的比例很低,但其含量并不很低,在酸性条件下,有释放导致污染的可能性。同位素示踪结果显示,研究区土壤和沉积物中积累的Pb、S为矿山物质来源。

ACCUMULATION OF HEAVY METALS IN SOILS AND SEDIMENTS AND DETERMINATION OF POLLUTANT SOURCE BY Pb AND S ISOTOPIC TRACERS

In the study region, heavy metals in soils and sediments, as observed, greatly exceed the regional background values. Correlation analyses revealed high positive correlations between Fe_2O_3 and heavy metal concentrations, indicating stronger abilities of Fe_2O_3 to fix heavy metals. Very high CPI values could be figured out for heavy metals in soils and sediments, showing a very high pollution degree of heavy metals. Results of sequential extraction demonstrated that heavy metals were bound mainly to carbonate, iron and manganese oxides, and minerals; only a few exchangeable fractions were extracted. But exchangeable, fraction metals are high in concentrations, indicating a pollution possibility by heavy metal released under acidic conditions. Pb and S isotopic tracers gave results that heavy metals accumulated in soils and sediments were mainly from mine substances,especially those from local Zn smelting in the region.