土壤微生物对除草剂乙草胺污染的响应和指示

采用除草剂乙草胺作为土壤污染因子, 在人工可控制条件下, 研究乙草胺对土壤微生物细菌、真菌和放线菌数量及土壤微生物量碳的影响, 并探讨这些微生物学指标对土壤中乙草胺污染状况的指示.研究结果表明: 在整个试验过程中, 除草剂乙草胺在短时间内对微生物区系能产生明显抑制作用, 但随着时间增加和污染物的分解, 微生物数量逐渐得到恢复.在短时间抑制过程中, 细菌、放线菌数量以及微生物量碳与乙草胺浓度的对数之间有很好的剂量效应关系, 第7 d细菌数量与乙草胺浓度对数的拟合公式为y = -2.97x + 12.36, R2 = 0.999 3; 放线菌数量与乙草胺浓度对数的拟合公式为y = -2.13x + 6.67, R2 = 0.956 4; 微生物量碳在第14 d与乙草胺浓度对数的拟合公式为y = -89.25x + 348.90, R2 = 0.995 4; 其相关性都达到显著水平.而真菌在受到乙草胺污染后, 受抑制现象并不明显, 真菌对乙草胺有较强的抗性.总之在短期污染条件下, 土壤中的细菌、放线菌数量以及微生物量碳可以很好地指示土壤中乙草胺的污染状况.

Indication and response of soil microbe to acetochlor

An experiment was conducted to determine the effect of acetochlor (a soil pollutant) on soil microbe and soil microbial biomass carbon. Then the potential of soil microbe and microbial biomass carbon as indicators for acetochlor pollution in soil was analyzed. The results show that soil microbe is inhibited by short-term acetochlor application, but it recovers over the long-run due to the acetochlor degradaton. During inhibition, the number of bacteria, actinomycete and microbial biomass carbon content exhibit negative linear correlation with the log of acetochlor concentration. On the 7th day, the correlation between the log of acetochlor concentration and bacteria and actinomycete are expressed in the respective equations as y = -2.97x + 12.36, R² = 0.999 3; and y = -2.13x + 6.67, R² = 0.956 4. For microbial biomass carbon, the correlation equation on 14th day is y = -89.25x + 348.90, R² = 0.995 4; which are all significant. However, the effect of acetochlor on fungi is insignificant and hardly noticeable. Hence soil bacteria, actinomycete number and microbial biomass carbon content can be as good indicators for soil pollution by acetochlor in the short-run.