多氯联苯污染土壤的微生物生态效应研究

Mircrobial Ecological Effects in Soil Contaminated with Polychlorinated Biphenyls

以多氯联苯(Polychlorinated biphenyls,PCBs)自然污染的农田土壤为材料,分析土壤中微生物区系组成、生物量C、N、土壤基础呼吸以及微生物群落功能多样性的变化。研究结果表明,在以4-氯、5-氯同系物为主的PCBs污染土壤中,污染程度对土壤细菌、放线菌的数量影响不明显,而真菌的数量除与土壤污染程度有关,可能还受到土壤pH等性状的影响;土壤微生物C、N与土壤基础呼吸随污染程度的加剧呈下降趋势,但微生物C/N基本没有变化;Biolog分析显示,土壤微生物代谢剖面(AWCD)及Simpson指数在污染程度相差较大的两组土壤样品中差异均达到了显著性水平,表明PCBs污染引起了土壤微生物群落功能多样性下降,降低了微生物对不同单一碳源底物的利用能力。

Four soils samples, which were collected from farmland soil contaminated with polychlorinated biphenyls （PCBs）for long term, were used to assess the effects of PCBs contents in soils on the soil microbial community structures, soil microbial biomass C, N, soil basic respiration. Meantime, the relationship between diversity of boil microbial community function and PCBs soil concentrations were evaluated by Biolog method. In the soils predominantly contaminated with 4-Cl and 5-Cl congeners of PCBs, fungal population was influenced by PCBs contents as well as by other properties of soils such as pH. Meanwhile, populations of bacteria and actinomycetes were little influenced by PCBs in soils. However, soil microbial biomass C, N, and soil basal respiration all decreased with PCBs contents increasing in soils. Among them, significant differences were detected between heavily contaminated and lightly contaminated soil. And compared with soil basal respi- ration in S1 sample, it decreased 20.23% in S4 sample. The microbial C/N ratios were little influenced by PCBs soil concentrations. Soil microbial metabolic profiles （AWCD）values increased with incubation time, and significant differences of AWCD and Simpson indexes were both found by Biolog method between the heavily contaminated soils and lightly contaminated soils, especially in incubation 48 h. Therefore the diversity of soil microbial function and microbial capability to utilize the single carbon substrates were influenced by PCBs in soil.