Abstract
Landfills have been identified as one of the major sources of greenhouse gas (GHG) emissions and as a contributor to climate change. Landfill facilities exhibit considerable spatial and temporal variability of both methane (CH4) and carbon dioxide (CO2) rates. The present work aimed to evaluate the spatial distribution of CH4 and CO2 and their δ13C isotopic composition originating from a municipal landfill site, to identify its contribution to the local GHG budget and the potential impact on the air quality of the immediate surroundings in a short-term response to environmental conditions. The objective was met by performing direct measurements of atmospheric CO2 and CH4 at the selected monitoring points on the surface and applying a binary mixing model for the determination of carbon isotopic ratios in the vicinity of the municipal waste landfill site. Air samples were collected and analysed for isotopic composition using flask sampling with a Picarro G2201-I Cavity Ring-Down Spectroscopy (CRDS) technique. Kriging and Inverse distance weighting (IDW) methods were used to evaluate the values at unsampled locations and to map the excess of GHGs emitted from the landfill surface. The large off-site dispersion of methane from the landfill site at a 500 m distance was identified during field measurements using isotopic data. The mean δ13C of the landfill biogas emitted to the surrounded atmosphere was −53.9 ± 2.2‰, which corresponded well to the microbial degradation processes during acetate fermentation in the waste deposits. The calculated isotopic compositions of CO2 (δ13C = −18.64 ± 1.75‰) indicate the domination of biogenic carbon reduction by vegetation surrounding the landfill. Finally, amounts of methane escaping into the air can be limited by the appropriate landfill management practices (faster covers active quarter through separation layer), and CH4 reduction can be achieved by sealing the cover on the leachate tank.
Highlights
Carbon dioxide (CO2 ) and methane (CH4 ) derive from a majority of natural and anthropogenic sources and play a critical role in regulating the Earth’s climate by trapping heat and contributing to overall global warming [1,2,3]
This study presented the spatial characteristic of atmospheric CO2 and CH4 levels in short-term responses to environmental conditions observed in the vicinity of the municipal waste landfill for our August 2017 sampling campaign
Our investigation confirmed the negative influence of the municipal waste landfill site, especially at the hot-spot zones, on the local greenhouse gas (GHG) balance in the surrounding atmosphere, but less than assumed
Summary
Carbon dioxide (CO2 ) and methane (CH4 ) derive from a majority of natural and anthropogenic sources and play a critical role in regulating the Earth’s climate by trapping heat and contributing to overall global warming [1,2,3]. Methane and carbon dioxide are major components of landfill gas (biogas), accounting for ~45–60%. ~40–60% of the total gas emissions [4], respectively; their variations depend on the composition and age of the waste [5], as well as landfill operating procedures [6]. Landfill gas is produced by the degradation of organic matter in the waste mix in a series of biological and physicochemical mechanisms under anaerobic conditions [5,8,9]. The production of landfill gas consists of the following five phases: (1) hydrolysis (in the presence of oxygen complex organic polymers, become converted into simple compounds, sugar, fatty acids, and amino acids, further O2 becomes depleted while CO2 is generated),
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