Biological Characteristics And Biodegradation Of Organochlorine Pesticides In Contaminated Soils

Understanding and montoring the biological chracteristics of organochlorine pesticides contaminated soil is of fundamental importance for the design, implementation and evaluation of a biodegradation process. Focusing on an abandoned sites of pesticide industry, the present study was devoted to the illustration of the occurrence of organochlorine pesticides(OCPs) and their environmental impact on soil microbial community and ecology. Pilot-scale remediation of highly OCPs-contaminated soil was conducted, in which both the removal OCP and the dynamic evolution of microbial community was monitored by the 454 pyro sequencing method.Eighten OCPs were identified from the surface soil samples in which hexachlorocyclohexanes(HCHs) and dichlorodiphenyltrichloroethanes(DDTs) were the predominant contaminantswith a 100% detection rate. The highest concentration of OCPs was 4 to 5 orders of magnitude of the regulation values of China.With respect to the plant tissue samples,HCHs and DDTs were also detected at detection rate above 95%. OCP concentration in the rhizosphere soil was one to two orders of magnitude lower than the bare soil. The verical profiling of the OCPs distribution indicated amigration risky tendency.The effect of OCP contamination on the enzymatic activity, functional gens(linA and rdh-like) as well as the microbial ecology and diversity were examined, respectively. It was shown the existence of OCP greatlyinhibited the microbilal ecology and diversity. The microbial diversity was inversely correlated with the contamination level. At the same extend of contamination, the growth of plant mitigated the adverse impact of contamination on microbial diversity. The abundance of linA gene increased in response to the contamination level. The copy numbers of linA and RHD-like mRNA in the rhizosphere soil samples were 3 times higher than those in highly contaminated soils. A multivariate regression analysis was applied to elucidatethe contribution of contamination, environmental factors and plant growth to the evolution of microbial diversity.The effect of microbial and plant assisted degradation of OCP was evaluated under different conditions and evaluated in terms of the degradation rate and the dynamic evolution of microbial diversity. The maximum degradation rate of HCHs and DDTs reached 81% and 85%, respectively, after 90-day degradation. The analysis of microbial community and diversity, as well as Kocuria sp.P andlinA gene indicated that a unique pattern with the plant growth was generated, which showed a positive impact on the degradation of the contaminants. The results presented in this dissertation established a microbial ecological insight into the degradation of HCHs and DDTs in aged contaminated soil and microbial community evolution under the stress of contamination and other environmental factors, which are helpful for the design and implementation of OCP degradation.