Effect of exudates from sorghum sudanense grass roots on degradation of organochlorine pesticides in soils
PAN Sheng-wang1, LEI Zhi-hua1,2, WU Yun-xiao3, HE Mao-ping1
1. School of Architecture and Civil Engineering, Chengdu University, Chengdu 610106;
2. School of Medical Laboratorial Technics, Xinyang Vocational & Technical College, Xinyang 464000;
3. College of Life Sciences, Yan'an University, Yan'an 716000
pot experiments was conducted to evaluate the potentials of exudates of sorghum sudanense in reinforcing the phytoremediation of organochlorine pesticides (OCPs), the removal efficiencies of OCPs and its main components in soils with initial concentrations ranging 66.67 to 343.61mg/kg were determined, microbial ecological characteristics, including composition, numbers, and community structure and function, were investigated, and their influence on soil microbial biomass carbon, microbial biomass nitrogen and their phospholipid fatty acids (PLFA), as well as roles which root exudates played in the process of phytoremediation were discussed. Results showed that addition of the exudates significantly reinforced dissipation of OCPs in soils. During the entire experiment, the soil-microbe systems (treatment Ⅱ, TR2) mediated by the exudates exhibited enhancement on OCPs degradation in soils. And, the highest OCPs removal rate at 79.32% was achieved when the exudates were added in the presence of rhizospheric microbes (TR2); whereas, without the exudates (treatment I, TR1), the removal rate was merely 40.46%, and it was 18.69% in soils (CK) spiked with 0.05% NaN3 to suppress the microbial effect. Under the same treatment conditions, the enhanced removal rates of hexachlorocyclohexane (HCHs), hexachlorobenzene (HCB), toxaphene, aldrin and γ-chlordane were much higher than the total amount of OCPs while the extent of enhanced dissipation of dichloro-diphenyl-trichloroethanes (DDTs), mirex, endosulfanⅠ, dieldrin and heptachlor epoxide were always lower than that in the corresponding soils. Furthermore, soils microbial biomass carbon and nitrogen, increased increasing exudates concentration under the same level of the OCPs stress, and there were close relationship between OCPs degradation and soil microbes.In the test soils which PLFA probed by GC-MS, their microbial community was dominated by bacteria,and followed by fungi, and they had the same variation trend as the OCPs degradation, which indicated OCPs in soils were degraded mainly by bacteria and fungi, and influence of the exudates in OCPs degradation were mainly carried out through modifying bacterial and fungi population ecological characteristics. Thus, rhizosphere effect from of sorghum sudanense under the OCPs stress might encourage the growth of rhizospheric microbes and modify their community structure in the process of phytoremediation leading to the improved OCPs degradation.
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PAN Sheng-wang, LEI Zhi-hua, WU Yun-xiao, HE Mao-ping. Effect of exudates from sorghum sudanense grass roots on degradation of organochlorine pesticides in soils. CHINA ENVIRONMENTAL SCIENCECE, 2017, 37(8): 3072-3079.
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