Song Yang, Bian Yongrong, Wang Fang, Herzberger Anna, Yang Xinglun, Gu Chenggang, Jiang Xin
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, PR China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, PR China.
Chemosphere. 2017 Nov;186:116-123. doi: 10.1016/j.chemosphere.2017.07.139. Epub 2017 Jul 28.
Anaerobic reductive dechlorination is an important degradation pathway for chlorinated organic contaminants in paddy soil. This study investigated the effects of amending paddy soil with wheat straw biochar on both the dechlorination of hexachlorobenzene (HCB), a typical highly chlorinated contaminant, and on the structure of soil bacteria communities. Soil amendment of 0.1% biochar did not significantly affect the dechlorination of HCB in the soil. However, biochar amendment at higher application levels (5%) stimulated the dechlorination of HCB in the first month of anaerobic incubation and inhibited the dechlorination of HCB after that period. The stimulation effect may be ascribed to the graphite carbon and carbon-centered persistent radicals, which are redox active, in biochar. The inhibiting effect could be partly ascribed to the reduced bioavailability of HCB in biochar-amended soils. High-throughput sequencing revealed that the amendment of biochar changed the soil bacterial community structure but not the bacterial abundances and diversities. The relative abundance of Dehalococcoidaceae in the tested soils showed a significant relationship with the dechlorination percentages of HCB, indicating that Dehalococcoidaceae may be the main HCB-dechlorinating bacteria in the studied paddy soil. The results indicated that low application levels of biochar did not affect the dechlorination of HCB in the paddy soil, while high application levels of biochar mainly inhibited the dechlorination of HCB due to the reduced bioavailability of HCB and the reduced abundances of certain dechlorinating bacteria in the biochar-amended paddy soil.
厌氧还原脱氯是稻田土壤中氯代有机污染物的重要降解途径。本研究调查了用小麦秸秆生物炭改良稻田土壤对典型高氯污染物六氯苯（HCB）脱氯以及土壤细菌群落结构的影响。添加0.1%生物炭对土壤中HCB的脱氯没有显著影响。然而，较高添加量（5%）的生物炭在厌氧培养的第一个月刺激了HCB的脱氯，之后则抑制了HCB的脱氯。这种刺激作用可能归因于生物炭中具有氧化还原活性的石墨碳和以碳为中心的持久性自由基。抑制作用可能部分归因于生物炭改良土壤中HCB生物有效性的降低。高通量测序表明，生物炭的添加改变了土壤细菌群落结构，但没有改变细菌丰度和多样性。受试土壤中脱卤球菌科的相对丰度与HCB的脱氯百分比呈显著相关，表明脱卤球菌科可能是所研究稻田土壤中主要的HCB脱氯细菌。结果表明，低添加量的生物炭不影响稻田土壤中HCB的脱氯，而高添加量的生物炭主要由于HCB生物有效性降低以及生物炭改良稻田土壤中某些脱氯细菌丰度降低而抑制了HCB的脱氯。
