化工厂污染区复垦后的土壤和蔬菜重金属含量与风险评价

Environmental Risk Assessment of Heavy Metal in Soil and Vegetable from the Chemical Plant Reclamation Land

以湖南省某化工厂重金属污染土壤复垦区为研究区域,采集复垦区和对照区的表层土壤(0~20 cm)与当季蔬菜(莴笋、大蒜、紫苏、白菜、薤白和艾蒿),分析了样品中五种重金属含量(Cd、Zn、Cu、Pb、Cr),然后对复垦后土壤环境进行安全性评价。结果表明:原厂区内、排污口及二次污染区土壤重金属Cd明显高于其他区域,客土处理土壤明显低于原土Cd含量,但含量依然超标,单因子污染指数为1.65~5.42,土壤重金属综合污染指数为1.22~3.95;根茎类蔬菜中Cd含量超过限量标准,含量最高的为薤白,超过标准90%,影响居民健康;土壤和蔬菜中Zn、Cu、Pb、Cr元素均达标。翻耕与客土复垦有一定效果,但是复垦土壤仍然不适合种植农作物。

The reclamation soil samples and seasonal vegetable s(Lactuca sativa L, Allium sativum L, Perilla frutescens, Brassica rapa pekinensis, Allium macrostemon Bunge, Artemisia argyi) were collected in the typical heavy metal pollution reclamation land of Hunan Province in China. The concentrations of Cd, Zn, Cu, Pb and Cr were determined by hydride generation atomic fluorescent spectrometry. The results showed that the concentrations of Cd in soil samples of the factory, outlet and contaminated zone were higher than other soil samples. The concentration of Cd in the reclamation soil sample was lower than that of the previous soil, but the concentration was still higher than the value of soil environmental standard. The range of single pollution index of Cd was 1.65 ~ 5.42.The range of comprehensive pollution index of five heavy metals was 1.22 ~ 3.95. The concentration of Cd in the tuber vegetables was higher than the maximum level of contaminants in food. Meanwhile, the Allium macrostemon Bunge had the highest concentration, exceeding the standard more than 90%, while other heavy metals in soils and vegetables were below standards. Tillage and foreign soil reclamation had certain effects to contaminated soil, but reclamation land was not suitable for planting crops.