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Municipal solid waste (MSW) landfills are regarded as one of the major sources of greenhouse gas (GHG) emissions across the world. In order to control these emissions, an innovative and sustainable biogeochemical cover system that consists of soil, biochar and basic oxygen furnace (BOF) slag is being developed to completely eliminate fugitive methane (CH4) and carbon dioxide (CO2) emissions from the landfills. The effectiveness of such cover systems is highly dependent on the survival and activity of methanotrophs under highly alkaline conditions induced by the presence of slag. In this study, a series of microcosm batch tests on landfill cover materials in different proportions were investigated to study the effect of cover materials on microbial CH4 oxidation in the mixed as well isolated systems. Results demonstrated negligible CH4 oxidation and substantial CO2 sequestration when the BOF slag was integrated/mixed with soil (pH~7) and biochar-amended soil (pH~11). However, layered or separated cover material conditions (biochar-amended soil overlain by slag and soil overlain by slag) demonstrated promising CH4 oxidation potential, thus concluding that extreme alkaline conditions inhibit the CH4 oxidation. Overall, this study showed that a layered system consisting of the soil or biochar-amended soil layer overlain by BOF slag layer is optimal for CH4 oxidation and subsequent CO2 sequestration. Large column experiments and field test plots are being performed to evaluate the long-term performance of the proposed geochemical cover system under dynamic environmental (moisture and temperature) conditions. 

Laboratory based long-term batch incubation study was carried out to assess the methane (CH4) uptake or removal capacity in the landfill cover soil, biochar-amended cover soil, and methanotrophic-activated biochar-amended cover soil. The soil was amended with biochar or activated biochar in two proportions: 2% and 10% by weight. The results indicate that the methanotrophic-activated biochar-amended soil exhibited higher CH4 uptake and oxidation rates when compared to soil and biochar-amended soil. The 10% methanotrophic-activated biochar-amended soil showed the highest CH4 uptake with the CH4 oxidation rate of 518.6 µg CH4/g/day and the landfill cover soil showed the least uptake with the CH4 oxidation rate of 88 µg CH4/g/day. Overall, this study demonstrates that the biochar activated with methanotrophs expedited the CH4 uptake process when compared to non-activated biochar-amended soil that takes longer time for microbial colonization and acclimatization. Furthermore, column studies and field scale studies under dynamic environmental conditions are being undertaken to evaluate the maximum removal of CH4 under typical landfill conditions. 

Peatlands play a critical role in the global carbon (C) cycle, encompassing ∼30% of the 1,500 Pg of C stored in soils worldwide. However, this C is vulnerable to climate and land‐use change. Ecosystem models predict the impact of perturbation on C fluxes based on soil C pools, yet responses could vary markedly depending on soil organic matter (SOM) chemistry. Here, we show that one SOM functional group responds strongly to environmental factors and predicts the risk of carbon dioxide (CO₂) release from peatlands. The molecular composition of SOM in 125 peatlands differed markedly at the global scale due to variation in temperature, land‐use, vegetation, and nutrient status. Despite this variation, incubation of peat from a subset of 11 sites revealed thatO‐alkyl C (i.e., carbohydrates) was the strongest predictor of aerobic CO₂production. This explicit link provides a simple parameter that can improve models of peatland CO₂fluxes.