Quantification of methane oxidation measuring isotopic signal in 13C on Spanish landfills

• Published in: Atmospheric pollution research Vol. 15; no. 9; p. 102198
• Main Authors: de la Fuente, María del Mar, Narros, Adolfo, Sánchez, Carlos, Rodríguez, Encarnación
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2024
• Subjects: Fractionation factor; Landfill; Landfill gas; Methane emissions; Methane oxidation; Fractionation factor; Methane oxidation; Landfill gas; Landfill; Methane emissions
• ISSN: 1309-1042; 1309-1042
• DOI: 10.1016/j.apr.2024.102198

Landfill emissions, particularly methane leaks detected by satellite, are drawing great attention in the last years as a mean for evaluate their contribution to the global warming effect. In contrast, models like IPCC often overestimate landfill methane emissions, prompting verification and mitigation system evaluation. Methane's higher warming capacity than carbon dioxide underscores the importance of promoting its oxidation as it traverses landfill layers. This oxidation raises the CH4–13C/12C ratio via bacterial biooxidation. This study quantified this fractionation using soil and surface gas samples from Spanish landfills and their degassing systems. Sampling relied on walkover surveys collecting samples in Tedlar bags, to analyze isotopic signals in the laboratory using WS-CRDS. Fractionation factors (α) ranged from 1.020 to 1.030, while the oxidized fraction (fox) spanned from no oxidation to 55% (δ13C of −45.83‰). Each ratio correlates with emission types like fugitive and dispersed emissions on plateaus, berms, slopes, sealing cracks, or pits. Understanding the methane oxidized fraction in each landfill is relevant for greenhouse gas emission model integration. [Display omitted] •Landfill CH4 oxidation quantification using 13C isotope signal via CRD Spectroscopy.•Selection of fugitive emissions landfill sampling points for walkover survey.•Wide range from no oxidation to a 55% CH4 oxidation.•Real oxidation fraction higher than Greenhouse Gas Emission model inputs.•Mitigation strategy: Enhance CH4 oxidation as it leaks through landfill layers.