铬渣堆放场中金属铬对周边土壤微生物毒性效应

Toxicity of metal chromium to microorganism activities in soil around chromium-containing slag heap

通过野外调查和采样分析,采用传统微生物平板培养方法,研究某铁合金厂区铬渣堆放场及周边土壤铬污染情况及其金属铬对土壤微生物数量和多样性的影响。结果表明:厂区内铬渣堆放场和厂外农业用地土壤总铬平均含量分别超过中国土壤环境质量二级标准的396%和173%,分别是对照区的17倍和9倍。厂区铬渣堆放场水溶性六价铬平均含量是对照区的67倍。随着铬污染程度的增加,土壤中3大类微生物细菌、真菌、放线菌均受到一定程度抑制,其中,对照区微生物总的数量分别是厂外污染区、厂内污染区的16倍和3倍,厂外污染区微生物总的数量是厂内污染区的5倍。厂区内铬渣堆放场旁土壤细菌、真菌和放线菌数量比对照区分别下降94%,82%和79%。厂区内铬渣堆放场旁土壤3大类微生物物种多样性最低。3种微生物相比,对重金属Cr的敏感程度由大至小依次是细菌,真菌和放线菌。

Based on field investigation and sample analysis of chromium polluted soil in and around the slag heap of a steel-alloy factory, total Cr and water soluble Cr（VI） concentrations microbial populations and diversity in soils were analyzed. The results show that mean concentrations of total Cr in the tested soil around the slag heap and farmland outside the factory exceed the Threshold of Secondary Environmental Quality Standard for Soil in China by 396% and 173% respectively and are 17 and 9 times higher than local background values respectively. Average water soluble Cr（VI） in soils around the slag heap is 67 times higher than that in control area. Bacteria, fungi and actinomycetes are inhibited with elevating Cr concentrations. The microbial populations in control areas are 16 and 3 times of the polluted soils outside and inside factory, respectively. The microbial populations in the polluted soils outside factory are 5 times of the heavily polluted soil inside factory. The populations of bacteria, fungi and actinomycetes decreased by 94%, 82% and 79%, respectively. Mcrobial diversity is the lowest in soils around the slag heap. Furthermore, various microorganisms show different sensitivity to chromium contamination. The sensitivity of microbial population to chromium contamination is in the order： bacteria〉 fungi 〉 actinomycetes.