[Characteristics and influencing factors of microbial function in soils around a typical mining smelter].

Soil microorganisms were sensitive to heavy metal pollution, whose ecological effect on soil microbial community was impacted by the interaction of contaminated stresses and environmental factors. To explore the dominant factors governing those effects in heavy metal contaminated soil, field investigation was conducted for soil from different land use types in an area surrounding a typical mining smelter in Hunan Province. Soil microbial function parameters including microbial biomass carbon (MBC), basal respiration (BR), substrate-induced respiration (SIR) and nitrification potential (PNR) were used as measure endpoints for ecological effect to reflect soil carbon and nitrogen cycling. The results showed that the effect of land use on MBC, BR, and SIR was insignificant. The dominant impacting factors on microbial functions included CaCl2 extracted Pb (CaCl2-Pb) and soil organic matter (SOM) content. Results of multiple regression analysis showed that soil CaCl2-Pb and SOM together explained 39.8%-58.3% of the total variations of BR, SIR and PNR in soil, when CaCl2-Pb and SOM ranged in 0.004-13.14 mg·kg-1 and 0.24%-4.34%, respectively. Significantly quantitative exposure-effect equations were developed between the responses of soil BR, SIR and PNR and soil CaCl2-Pb and SOM when soil samples with medium contents (namely, SOM 1.70%～2.36% and CaCl2-Pb 0.004-12.98 mg·kg-1), which meant they could be used to quantitatively assess the ecological effect of heavy metals on microbial community function as measure endpoints.土壤微生物对重金属污染胁迫敏感,但在实际野外环境中,土壤微生物群落生态效应通常是污染胁迫和环境因素综合作用的结果。为探究重金属污染土壤中微生物群落生态效应发生变化的主控因素,本研究以湖南省某典型矿冶区周边不同土地利用类型土壤为研究对象,以土壤碳氮循环过程主要的微生物功能指标土壤微生物生物量碳(MBC)、基础呼吸(BR)、诱导呼吸(SIR)和硝化潜势(PNR)为生态效应终点,进行采样调查分析。结果表明: 土地利用类型对MBC、BR和SIR影响均不显著;研究区土壤微生物功能的主要影响因子包括CaCl2提取态Pb(CaCl2-Pb)含量与土壤有机质(SOM)含量。多元回归分析结果表明,在CaCl2-Pb含量为0.004～13.14 mg·kg-1及SOM含量为0.24%～4.34%的条件下,土壤CaCl2-Pb和SOM含量可以共同解释土壤中BR、SIR和PNR总变异的39.8%～58.3%;中等含量下(SOM在1.70%～2.36%,CaCl2-Pb在0.004～12.98 mg·kg-1),土壤CaCl2-Pb和SOM含量与BR、SIR和PNR的变化能够建立显著的暴露-效应关系,可以作为测定终点定量评价重金属污染对微生物群落功能的生态效应。.