Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Firenze, Italy.
Instituto Volcanológico de Canarias (INVOLCAN), 38320 La Laguna, Tenerife, Canary Islands, Spain.
Sci Total Environ. 2020 Jul 15;726:138326. doi: 10.1016/j.scitotenv.2020.138326. Epub 2020 Apr 8.
Landfills for solid waste disposal release to the atmosphere a large variety of volatile organic compounds (VOCs). Bacterial activity in landfill cover soils can play an important role in mitigating VOC emission. In order to evaluate the effects of degradation processes and characterize VOCs composition in landfill cover soil, gases from 60 sites and along 7 vertical profiles within the cover soil were collected for chemical and isotopic analysis at two undifferentiated urban solid waste disposal sites in Spain: (i) Pinto (Madrid) and (ii) Zurita (Fuerteventura, Canary Islands). The CO/CH ratios and δC-CO and δC-CH values were controlled by either oxidation or reduction processes of landfill gas (LFG). VOCs were dominated by aromatics, alkanes and O-substituted compounds, with minor cyclics, terpenes, halogenated and S-substituted compounds. Degradation processes, depending on both (i) waste age and (ii) velocity of the uprising biogas through the soil cover, caused (i) an increase of degradation products (e.g., CO, O-substituted compounds) and (ii) a decrease of degradable components (e.g., CH, alkanes, alkylated aromatics, cyclic and S-substituted compounds). Terpenes, halogenated compounds, phenol and furans were unaffected by degradation processes and only depended on waste composition. These results highlight the fundamental role played by microbial activity in mitigating atmospheric emissions of VOCs from landfills. Nevertheless, the recalcitrant behaviour shown by compounds hazardous for health and environment remarks the importance of a correct landfill management that has to be carried out for years after the waste disposal activity is completed, since LFG emissions can persist for long time.
固体废物处理场向大气中释放出大量挥发性有机化合物（VOCs）。填埋场覆盖土壤中的细菌活动可以在减轻 VOC 排放方面发挥重要作用。为了评估降解过程的影响并表征填埋场覆盖土壤中 VOC 的组成，在西班牙两个未分化的城市固体废物处理场（i）Pinto（马德里）和（ii）Zurita（富埃特文图拉，加那利群岛），从覆盖土壤中的 60 个点和 7 个垂直剖面收集了气体，用于化学和同位素分析。CO/CH 比和 δC-CO 和 δC-CH 值受填埋气（LFG）的氧化或还原过程控制。VOCs 主要由芳烃、烷烃和 O 取代化合物组成，还有少量的环烃、萜烯、卤代和 S 取代化合物。降解过程取决于（i）废物年龄和（ii）上升沼气通过土壤覆盖的速度，导致（i）降解产物（例如，CO、O 取代化合物）增加和（ii）可降解成分（例如，CH、烷烃、烷基化芳烃、环烃和 S 取代化合物）减少。萜烯、卤代化合物、苯酚和呋喃不受降解过程影响，仅取决于废物成分。这些结果突出了微生物活动在减轻垃圾填埋场 VOC 大气排放方面的重要作用。然而，对健康和环境有害的化合物表现出的抗降解行为表明，必须在废物处置活动完成后的多年内进行正确的垃圾填埋场管理，因为 LFG 排放可能会持续很长时间。
