Meyer-Dombard D'Arcy R, Bogner Jean E, Malas Judy
Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL, United States.
Front Microbiol. 2020 Jun 3;11:1127. doi: 10.3389/fmicb.2020.01127. eCollection 2020.
Engineered and monitored sanitary landfills have been widespread in the United States since the passage of the Clean Water Act (1972) with additional controls under RCRA Subtitle D (1991) and the Clean Air Act Amendments (1996). Concurrently, many common perceptions regarding landfill biogeochemical and microbiological processes and estimated rates of gas production also date from 2 to 4 decades ago. Herein, we summarize the recent application of modern microbiological tools as well as recent metadata analysis using California, USEPA and international data to outline an evolving view of landfill biogeochemical/microbiological processes and rates. We focus on United States landfills because these are uniformly subject to stringent national and state requirements for design, operations, monitoring, and reporting. From a microbiological perspective, because anoxic conditions and methanogenesis are rapidly established after daily burial of waste and application of cover soil, the >1000 United States landfills with thicknesses up to >100 m form a large ubiquitous group of dispersed 'dark' ecosystems dominated by anaerobic microbial decomposition pathways for food, garden waste, and paper substrates. We review past findings of landfill ecosystem processes, and reflect on the potential impact that application of modern sequencing technologies (e.g., high throughput platforms) could have on this area of research. Moreover, due to the ever evolving composition of landfilled waste reflecting transient societal practices, we also consider unusual microbial processes known or suspected to occur in landfill settings, and posit areas of research that will be needed in coming decades. With growing concerns about greenhouse gas emissions and controls, the increase of chemicals of emerging concern in the waste stream, and the potential resource that waste streams represent, application of modernized molecular and microbiological methods to landfill ecosystem research is of paramount importance.
自《清洁水法》（1972年）通过以来，在美国设计并受监测的卫生填埋场已广泛存在，同时还依据《资源保护与回收法》副标题D（1991年）以及《清洁空气法修正案》（1996年）进行了额外管控。与此同时，许多关于垃圾填埋场生物地球化学和微生物过程以及估计产气量的普遍认识也可追溯到20至40年前。在此，我们总结了现代微生物学工具的最新应用以及近期使用加利福尼亚州、美国环境保护局和国际数据进行的元数据分析，以勾勒出垃圾填埋场生物地球化学/微生物过程及速率的演变观点。我们聚焦于美国的垃圾填埋场，因为这些填埋场均统一遵循国家和州对设计、运营、监测及报告的严格要求。从微生物学角度来看，由于在每日填埋废物并覆盖土壤后，缺氧条件和甲烷生成会迅速形成，美国1000多个厚度超过100米的垃圾填埋场构成了一大组广泛分布的分散“黑暗”生态系统，这些生态系统以食物、园林垃圾和纸质底物的厌氧微生物分解途径为主导。我们回顾了过去关于垃圾填埋场生态系统过程的研究发现，并思考现代测序技术（如高通量平台）的应用可能对该研究领域产生的潜在影响。此外，由于填埋废物的组成不断演变，反映了社会的短暂实践，我们还考虑了已知或疑似在垃圾填埋场环境中发生的异常微生物过程，并提出了未来几十年所需的研究领域。随着对温室气体排放和控制的日益关注、废物流中新兴关注化学品的增加以及废物流所代表的潜在资源，将现代化的分子和微生物学方法应用于垃圾填埋场生态系统研究至关重要。
