重金属复合污染下红壤微生物活性及其群落结构的变化

在室内培养条件下,应用4因素5水平二次正交回归旋转组合设计方案,对重金属复合污染红壤的微生物活性及群落功能多样性进行了研究。结果表明,在Cu、Zn、Pb、Cd复合污染生境中重金属的微生物毒性效应发挥主要由Cd、Cu两元素决定,其生物毒性顺序表现为:Cd>Cu>Zn>Ph,红砂泥中表现较为突出。与单一镉、单一铅污染处理相比,重金属复合污染对供试红壤微生物生物活性及其群落功能多样性的影响并非仅仅表现出简单的加和作用,同时还存在协同作用和拮抗作用。典型相关分析显示,红壤微生物活性与重金属含量之间关系密切,第一对典型变量的相关系数r达0.885 8、0.932 8,均达极显著水平(p<0.001), 说明重金属复合污染与红壤微生物间存在较为稳定的数量反馈机制,红壤总体微生物活性指标能较好地反映供试红壤重金属复合污染状况,可作为重金属污染红壤环境质量评价及量化分类的有效指标。

CHANGES IN MICROBIAL ACTIVITIES AND ITS COMMUNITY STRUCTURE OF RED EARTHS POLLUTED WITH MIXED HEAVY METALS

An incubation experiment designed by second-order regression orthogonal rotation was conducted to study soil microbial activities and functional diversity of microbial community in red earths polluted by copper, zinc, lead and cadmium compound state. The results showed that soil microbial activities and functional diversity of microbial community were inhibited very significantly or significantly by heavy metals compound pollution. Moreover, soil microbial biomass carbon (SMBC), soil basal respiration and functional diversity of microbial community are very sensitive to the level of heavy metals pollution. At the same time, the relative biological toxicity of heavy metals to soil microbial parameters were in the order: cadmium > copper > zinc > lead. The results of canonical correlation analysis showed that the first ( r = 0.885 8) and second ( r = 0.932 8) canonical correlation coefficients were significant, which suggested that there exists a stable feed-back mechanism between soil microorganism and heavy metals contents in red earths. The main factors analysis opened out that the total microbial ecological index might be a useful parameter to assess changes in soil quality with management of these highly contaminated soils. So it is feasible to use soil total microbial parameters as primary biochemical index to evaluate the effect of heavy metals compound pollution on red earth environmental quality.