填埋场覆盖土层中好氧甲烷碳对含硫恶臭气体生物代谢的影响及其调控机制

Aim to the pollution of methane and sulfur-containing odor in landfills, the interface between landfill gas and atmosphere, landfill cover soils, will be chosen as the research object in this project. The traditional methods for studying microorganisms, stable isotope probing and molecular techniques will be used to study the following aspects: 1) metabolic characteristics of methanotrophs and their gene expression at different concentrations of sulfur-containing odor, methane and oxygen; 2) the fate of methane-derived carbon in aerobic oxidation in landfill cover soils and its effect on the removal of sulfur-containing odor; 3) the functional microorganisms and their metabolic characteristics involved in the degradation of methane-derived carbon in aerobic oxidation with the coexistence of methane and sulfur-containing odor; 4) the contribution of methane-derived carbon to the landfill cover soil system and 5) the relationship among the environmental factors in landfill cover soil (mainly including oxygen concentration and methane-derived carbon), the functional microorganisms in the degradation of methane-derived carbon and sulfur-containing odor and their functional gene expression. Thus, influence mechanism of methane-derived carbon in aerobic oxidation on removal of sulfur-containing odor will be clarified. And the controlling techniques of landfill cover soils at the core of oxygen concentration will be brought up to mitigate the emissions of methane and sulfur-containing odor from landfills. The results will provide foundational information and theoretical basis to scientificly utilze environmental effect of landfill cover soils to mitigate pollution of landfill gas.

针对垃圾填埋场中甲烷和含硫恶臭气体的环境污染问题，本项目拟选择“填埋气—大气”体系的环境界面—覆盖土层为研究对象，结合传统的微生物培养技术、稳定性同位素探针、分子生物学等技术，研究在不同含硫恶臭气体、甲烷与氧气浓度下甲烷氧化菌的代谢特性和基因表达特征，探讨覆盖土层中好氧甲烷碳的归趋及其对含硫恶臭气体净化性能的影响特性，分析含硫恶臭气体共存下覆盖土层中好氧甲烷碳代谢的主要功能微生物及其代谢特征，量化在覆盖土系统中好氧甲烷碳的贡献，解析覆盖土层环境因子（主要是氧浓度和甲烷碳等）、甲烷碳和含硫恶臭气体代谢的主要功能微生物与其功能基因表达间的关系，从而阐明覆盖土层好氧甲烷碳对含硫恶臭气体净化性能的影响机制，提出以氧浓度为核心的填埋场甲烷和含硫恶臭气体减排的覆盖土层控制技术。为科学利用垃圾填埋场覆盖土层的环境效应，减少填埋气的环境污染提供基础性资料和理论依据。

针对垃圾填埋场恶臭污染和温室气体排放的问题，项目以填埋场覆盖土层为研究对象，从好氧甲烷氧化菌、稳定性同位素探针（SIP）微宇宙和覆盖土层等角度，研究了含硫恶臭气体胁迫对好氧甲烷氧化菌的代谢特性，探讨了填埋场覆盖土层中含硫恶臭气体和甲烷共存下好氧甲烷氧化碳代谢的主要功能微生物及其代谢特征，解析了覆盖土层环境因子（主要是氧浓度和甲烷氧化碳等）、甲烷氧化碳和含硫恶臭气体代谢的主要功能微生物与其功能基因表达间的关系，诠释了填埋场覆盖土层中好氧甲烷氧化对含硫恶臭气体净化性能的影响机制。结果表明，覆盖土层能够有效地削减填埋场中含硫恶臭气体和甲烷的排放。甲烷的存在能够促进覆盖土含硫恶臭气体的生物转化，提高覆盖土中甲烷氧化菌对含硫恶臭气体如甲硫醚（DMS）及其碳的利用，促使更多的DMS-C流向非甲基营养微生物。同时，DMS胁迫会增加甲烷氧化碳流向覆盖土中有机物，贮存于覆盖土。氧气浓度是影响填埋场覆盖土中含硫恶臭气体和甲烷生物转化的重要因子，低氧浓度有利于覆盖土甲烷氧化过程中甲烷氧化碳的分泌，提高有机碳的转化率，促进覆盖土中非甲烷氧化菌的生长，从而提高填埋场覆盖土的生态效能，减少碳的排放。研究也发现覆盖土中甲烷氧化菌Methylobacter和Thiobacillus具有CH3SH氧化酶mtoX同源基因，可能参与CH3SH降解代谢。好氧甲烷氧化菌Methylomonas koyamae为模式生物，初步研究也发现Methylomonas koyamae能够代谢含硫恶臭气体，其对CH3SH代谢可能与SELENBP1、sqr和glpE基因相关。研究结果可为科学利用填埋场覆盖土层的环境效应，减少填埋气的环境污染提供基础性资料和理论依据。