Soil microorganisms would reproduce rapidly and migrate directionally under the applied electric field. In this study, tetradecane-degrading bacteria were added at different locations in soil, and 1 V·cm-1 unidirectional DC electric field was applied to investigate the migration, distribution, and degradation characteristics of target bacteria in soil. The results showed that microorga-nisms migrated to the cathode and anode by electrodialysis and electrophoresis, respectively. The number of microorganisms migrated by electrodialysis was 3.5 times of that by electrophoresis. The application of electric field could make the soil environment spatially heterogeneous to affect the growth of microorganisms. The average number of soil microorganisms under electric field was 1.16×108 CFU·g-1(6 days), which was 2.3 times of that without electric field. S2 to S4 were the efficient growth areas of microorganisms, with the average number after 30-day electric treatment being 2.8-3.5 times of that on the anode and cathode, and 2.1 times of that in the control. There was a significant positive correlation between the tetradecane degradation rate and the number of microorganisms (r=0.895, P＜0.05). The optimal tetradecane degradation region was near the cathode (S4), where its degradation rate reached 94.6%. Based on these results, a model modified by environmental factors was established to simulate the spatial distribution of microorganisms under the combined effect of electrokinetic stimulation and transportation. According to the model, the number distribution of microorganisms could be deduced when exogenous bacteria were added in a fixed section. The results provide a theoretical basis for the efficient import of exogenous functional bacteria in electrokinetic-bioremediation of organic contaminated soil.
外加电场下土壤微生物会发生快速繁殖和定向迁移.本研究在十四烷污染土壤中不同位置投加十四烷高效降解菌,并施加1 V·cm-1的单向直流电场,考察目标菌群的迁移分布及降解特征.结果表明:微生物受电渗析和电泳作用分别向阴极和阳极迁移,电渗析迁移量是电泳的3.5倍.同时,施加电场还会使土壤环境在空间上存在差异进而影响微生物生长,施加电场的土壤中微生物数量平均值为1.16×108 CFU·g-1 (6 d),是不施加电场处理组的2.3倍;S2～S4区是微生物的高效生长区域,电动30 d后,区域平均数量是阴阳极的2.8～3.5倍,是对照处理组的2.1倍.十四烷降解率与微生物数量呈显著正相关关系(r=0.895, P＜0.05),最佳降解区域在近阴极区(S4),可达94.6%.基于试验结果模拟,建立了环境因子修正的电动区域微生物分布模型.该模型结合电动激活和电动运移作用对土壤微生物的叠加影响,实现了定点投加微生物在电动过程中数量的分布模拟.研究结果可为外源功能菌在电动-微生物修复有机污染土壤中的高效引入提供理论依据.
Keywords: electrokinetic; microbial migration; spatial distribution model.