重金属污染对红壤旱地小节肢类土壤动物群落结构的影响

土壤重金属污染对农田土壤节肢动物的影响是其环境风险评价和监测的重要方面。基于现有国家土壤环境质量二级标准(GB 15618—1995),设计2个浓度重金属Cd(0.3 mg/kg,0.6 mg/kg)、Pb(125 mg/kg,250 mg/kg)和As(30 mg/kg,60 mg/kg)污染的田间试验,分别研究Cd、Pb和As对红壤旱地小节肢类土壤动物群落组成和多样性的影响。结果表明,试验土壤小节肢类动物共11类群,其中符跳属、棘跳属、蜱螨目为本地区红壤旱地的主要类群,占全部捕获小节肢类土壤动物总数的78%。重金属Pb、As高浓度污染分别显著降低了土壤弹尾目的个体密度73.5%、55.2%,而Cd高浓度污染对其无显著影响,仅降低15.9%;As和Cd高浓度污染分别显著降低了土壤蜱螨目的个体密度74.3%、36.4%,而Pb高浓度污染对其无显著影响。Pb、As和Cd污染对小节肢类土壤动物群落多样性指数均无明显影响。因此,与丰度相比,多样性指数对重金属污染反应的灵敏度较差。主成分分析表明,前气门亚目、符跳属和棘跳属的得分值较高,为小节肢类土壤动物群落中的主导因子,可作为未来该地区重金属污染环境影响监测的重要指标生物和重金属污染阈值研究的重要生态受体。

Effects of heavy metal pollution on soil microarthropods in upland red soil

The rapid development of industrialization, urban-rural integration and agricultural activities are raising pollutions in China, especially pollutants of heavy metals in farmland soil. Effect of heavy metal pollutants on soil arthropods was an important part of their risk assessment and environmental impact monitoring. Based on the methods of National Soil Environmental Quality Standard of China (GB 15618-1995), Cd (0.3 mg/kg and 0.6 mg/kg), Pb (125 mg/kg and 250 mg/kg) and As (30 mg/kg and 60 mg/kg) were added to upland of red soil respectively, to evaluate their effects on the composition and diversity of soil microarthropods under field conditions. Eleven taxonomic groups of soil microarthropods were observed and Folsomia, Onychiurus and Acarina were the dominant groups, accounting for up to 78% of the total soil microarthropods obtained. Pb and As pollution in high concentration levels significantly decreased the abundance of Collembola by 73.5%, 55.2% respectively, and Cd pollution in high concentration levels did not have significant effects on Collembola. As and Cd pollution in high concentration levels significantly decreased the abundance of Acarina by 74.3%, 36.4% respectively, and Pb pollution in high concentration levels did not have significant effects on Acarina. However, Pb, As and Cd showed no significant influences on soil biodiversity, as estimated by the Shannon and Simpson indices. Therefore, the biodiversity was less sensitive to heavy metal pollution than the abundance of soil invertebrates under field conditions. The results of the Principal Component Analysis suggested that the values of Folsomia, Onychiurus and Prostigmata were higher in the comprehensive principal component, indicating they were the dominant factors of the soil microarthropoda community, and could act as one of the indicator species to monitor the environmental impacts of heavy metal pollution as well as the important ecological receptors for studying the threshold of heavy metal pollution in the future.