表面活性剂强化微生物修复DDTs-PAHs复合污染农田土壤影响研究

摘要

滴滴涕(DDTs)和多环芳烃(PAHs)是土壤中典型的持久性有机污染物,环境毒性强,可对生物体产生不利影响.采用田间试验,研究阴-非离子混合表面活性剂[十二烷基苯磺酸钠(SDBS)和失水山梨醇单油酸酯聚氧乙烯醚(Tween80),混合质量比为2∶3]和生物表面活性剂鼠李糖脂(RL)对混合菌[球形节杆菌(Arthrobacter globiformis)和甲基营养型芽孢杆菌(Bacillus methylotrophicus),混合体积比为2∶1]在农田土壤滴滴涕-多环芳烃(DDTs-PAHs)复合污染修复过程中的强化作用.结果表明,SDBS-Tween80和RL均能不同程度地促进混合菌对农田土壤中DDTs-PAHs的降解.在SDBS-Tween80强化混合菌处理中,当SDBS-Tween80处理量为100 mg·kg-1时,土壤中DDTs和PAHs的150 d降解率最高,分别达到57.8％和35.6％,比单独混合菌处理分别提高了14.9％和11.9％.在RL强化混合菌处理中,当RL处理量为5 mg·kg-1时,土壤中DDTs和PAHs的150 d降解率最高,分别达到50.3％和28.6％,比单独混合菌处理分别提高了7.4％和4.9％.因此,SDBS-Tween80的最佳用量比RL更有利于提高DDTs-PAHs复合污染土壤的生物修复效果,DDTs和PAHs降解率提高8％左右,且SDBS-Tween80的修复成本更低.当1 00 mg·kg-1 SDBS-Tween80能显著提高p,p'-DDE和高环数PAHs的降解率,分别为63.0％和30.6％,比单独混合菌处理分别提高了18.8％和12.7％,该方法在复合污染土壤修复中具有良好的应用前景.%Dichlorodiphenyltrichloroethanes (DDTs) and polycyclic aromatic hydrocarbons (PAHs) are typical persistent organic pollutants (POPs) in soils,which has environmental toxicity and caused negative impacts on organisms.The enhanced effects of anionic-nonionic mixed surfactant [sodium dodecyl benzene sulfonate (SDBS) and polyoxyethylene (80) sorbitan monolaurate (Tween 80),the mixture mass ratio of 2:3] and biosurfactant rhamnolipids (RL) on the bioremediation of DDTs-PAHs with mixed bacteria [Arthrobacter globiformis and Bacillus methylotrophicus,the mixture volume ratio of 2:1] in co-contaminated farmland soil were investigated based on a field survey,The results showed that SDBS-Tween80 and RL could enhance the degradation rates of DDTs and PAHs when bioremediated with mixed bacteria.In the SDBS-Tween80-enhanced mixed bacteria treatments,when the applied concentration of SDBS-Tween80 was 100 mg·kg-1,the highest degradation rates of DDTs and PAHs were up to 57.8％ and 35.6％ within 150 d,and which were 14.9％ and 11.9％ higher than that of the mixed bacteria treatment alone.In the RL-enhanced mixed bacteria treatments,when the addition concentration of RL was 5 mg·kg-1,the highest degradation rates of DDTs and PAHs were up to 50.3％ and 28.6％ within 150 d,and which were 7.4％ and 4.9％ higher than that of the mixed bacteria treatment alone.Therefore,the optimum concentration of SDBS-Tween80 for biodegradation of DDTs-PAHs in co-contaminated farmland soil was approximately 8％ higher than that of RL,and the bioremediation was more cost-effective for SDBS-Tween80.Meanwhile,at the best optimum concentration of SDBS-Tween80 was 100 mg·kg-1,the corresponding degradation rates of p,p'-DDE and high-rings PAHs were significantly increased,and up to 63.0％ and 30.6％ respectively,which were 18.8％ and 12.7％ higher than that of the mixed bacteria treatment alone.This method has prospective application in the field of remediation of co-contaminated soils.