Effect of activated carbon amendment on bacterial community structure and functions in a PAH impacted urban soil.

We collected urban soil samples impacted by polycyclic aromatic hydrocarbons (PAHs) from a sorbent-based remediation field trial to address concerns about unwanted side-effects of 2% powdered (PAC) or granular (GAC) activated carbon amendment on soil microbiology and pollutant biodegradation. After three years, total microbial cell counts and respiration rates were highest in the GAC amended soil. The predominant bacterial community structure derived from denaturing gradient gel electrophoresis (DGGE) shifted more strongly with time than in response to AC amendment. DGGE band sequencing revealed the presence of taxa with closest affiliations either to known PAH degraders, e.g. Rhodococcus jostii RHA-1, or taxa known to harbor PAH degraders, e.g. Rhodococcus erythropolis, in all soils. Quantification by real-time polymerase chain reaction yielded similar dioxygenases gene copy numbers in unamended, PAC-, or GAC-amended soil. PAH availability assessments in batch tests showed the greatest difference of 75% with and without biocide addition for unamended soil, while the lowest PAH availability overall was measured in PAC-amended, live soil. We conclude that AC had no detrimental effects on soil microbiology, AC-amended soils retained the potential to biodegrade PAHs, but the removal of available pollutants by biodegradation was most notable in unamended soil.

我们从一项基于吸附剂的修复现场试验中收集了受多环芳烃（PAHs）污染的城市土壤样本，以解决对2%粉末状（PAC）或颗粒状（GAC）活性炭改良剂对土壤微生物学和污染物生物降解产生不良副作用的担忧。三年后，在GAC改良的土壤中，微生物细胞总数和呼吸速率最高。通过变性梯度凝胶电泳（DGGE）得出的主要细菌群落结构随时间的变化比因活性炭改良而产生的变化更为显著。DGGE条带测序显示，在所有土壤中都存在与已知的多环芳烃降解菌（如红串红球菌RHA - 1）亲缘关系最近的分类群，或已知含有多环芳烃降解菌的分类群（如赤红球菌）。通过实时聚合酶链反应进行定量，在未改良、PAC改良或GAC改良的土壤中，双加氧酶基因拷贝数相似。批量试验中的多环芳烃有效性评估显示，未改良土壤在添加和不添加杀菌剂的情况下差异最大，为75%，而总体上多环芳烃有效性最低的是在PAC改良的有活性土壤中。我们得出结论：活性炭对土壤微生物学没有有害影响，活性炭改良的土壤保留了生物降解多环芳烃的潜力，但通过生物降解去除可利用污染物在未改良土壤中最为显著。