Effect of Biochar on Adsorption, Biodegradation and Microbial Community Response of Steroid Hormones in Animal Manure-Amended Soils
Master of Science (MS)
Plant, Environmental Management and Soil Sciences
Widespread application of animal manure to agricultural land causes soil and water pollution of steroid hormones and antibiotics besides excessive nutrients. Manure-borne steroid hormones have received much attention because of their endocrine-disrupting effects on animals even in trace concentration. Hormones transport into water system through leaching and runoff from manure-amended soils. Application of biochar, a pyrogenic product of waste biomass, has been suggested to improve sorption ability of soil and influence the biodegradation of organic contaminant. The objective of this study was to investigate the effect of biochar on soil microbial community response to natural estrogen hormone 17 β-estradiol (E2) and synthetic hormone 17 α-ethinylestradiol (EE2) in manure-affected soils through measurement of phospholipid-derived fatty acids (PLFA) profiles. In addition, biochar effects on sorption-desorption and dissipation behaviors of EE2 in loam and clay soils were evaluated. For assessing the microbial process impact, hormone changes in microcosms of sterilized and non-sterilized soils were characterized using HPLC-MS/MS. The results showed that EE2 significantly decreased total microbial biomass by 26.7%. Biochar, while significantly increased total microbial biomass by 32.9%, did not reduce hormone’s negative effects on total microbial biomass. Biochar promote more gram negative and actinomycete than gram positive and fungi in soil, however had little effect on soil microbial activity and community structure under the stress imposed by EE2 or E2. The dissipation of EE2 in non-sterilized soils fit 1st order kinetics, whereas it was better described by zero-order kinetics. Biochar decreased overall dissipation of EE2 in both sandy loam and clay soils as well as microbial degradation of EE2. Biochar delayed the half-life of EE2 dissipation in soils from 0.74 to 2.1 days. The metabolites (E1 and E2) of EE2 were only detected in trace amount or below detection limit, indicating minor process of transformation in these soils. Biochar amendment increased the maximum sorption but decreased the water desorption of EE2 in both sandy loam and clay soil, respectively. Furthermore, biochar significantly increased non-extractable fraction of EE2, whereas reduced the EE2 bioavailability to microorganisms. Overall, this study demonstrated positive impacts of biochar on the retention of estrogen hormones in manure–affected soils.
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Wei, Zhuo, "Effect of Biochar on Adsorption, Biodegradation and Microbial Community Response of Steroid Hormones in Animal Manure-Amended Soils" (2017). LSU Master's Theses. 4617.
Wang, Jim J