TCLP法评估贵溪冶炼厂附近土壤重金属生态环境风险

Ecological risk assessments of heavy metals of inside the soil near Guixi smelter with TCLP

贵溪冶炼厂附近农田长期受到该厂重金属废水的污灌,导致土壤受到严重污染,相关土壤修复措施已开展多年。为了解该地区土壤重金属污染状况及植物修复效果,采集了该厂附近3种典型重金属污染土壤：未受修复土壤（A）、正在进行修复土壤（B）及已受植物修复的土壤（C）,TCLP法研究了土壤表层（0-20cm）中4种主要重金属（Cu、Pb、Cd、Zn）有效态重金属含量,并对其生态风险进行评估。结果显示,植物修复前土壤中重金属总量和有效态含量显著高于修复后土壤的含量;植物修复对4种重金属有效态及总量去除效果明显,去除率分别达Cu64.83%、61.35%;Cd 53.6%、46.67%;Zn 22.51%、8.88%和Pb 7.76%、4.84%;内梅罗综合指数法评价指出,修复前土壤处于重度污染,修复后土壤污染状况明显减轻,但依然处于中度污染,土壤中重金属Cu和Cd具有较强的生态风险,其主要原因为大气沉降所导致。

Farmlands near Guixi smelter have been irrigated by heavy metal sewage for a long time,which- and resulted in serious heavy metal pollution. The lated remediate work have been carried out for many years as well. In order to investigate the effect of the phytoremediation and ecological risk of the soil, three typical soil samples which have been polluted by heavy metal were collected near the smelter and marked with no repair soil （A）,under repairing soil （B） and the phytoremediated soil （C）. The available contents and the total amounts of Cu,Pb,Cd,Zn in the surface （0~20 cm） of the soil were determined by using tox- icity characteristic leaching procedure（TCLP）method. ,The ecological risk of the heavy metals was evalua- ted by Nemero Index subsequently. The results showed that the available contents and the total amounts of heavy metals in soil before phytoremediation were both significantly higher than those insideof soil after re- mediation. The removal effect of the four heavy metals by phytoremediation was obvious with the removal rates of Cu 64.83%,61.35%;Cd 53.6%,46.67%;Zn 22.51%,8.88% and Pb 7.76%,4.84%,respectivelution status have been reduced significantly after remediation, but it was still in moderate pollution. Among them Cu and Cd in the soil had strong ecological risks. Atmospheric precipitation is the main reason.