Comparative analysis of methane emission from dumpsites and rice plantations using a bespoke low-cost unit in Ile-Ife and Okemesi-Ekiti, Southwestern Nigeria

Abstract

Compared to carbon dioxide (CO₂), methane (CH₂ ) is a more potent greenhouse gas, trapping more heat than  CO₂ on a per molecule basis. With increasing levels of activities in prominent sources of methane such as 2 livestock farming, rice farming and waste  management, especially in developing economies like Nigeria, the need for a comprehensive and reliable CH₄ inventory cannot be over- emphasized. Using a bespoke low-cost 4 measuring unit, this study investigated the vertical profile and variability of methane around rice  farms and waste dumpsites. Findings show that ambient levels of methane around the rice farms ranged between 26 ppm and 698  ppm and were highest at temperatures >30°C while lower concentrations were measured at lower temperatures. High methane  concentrations were observed at a height of around 15 m and gradually decreased with increasing altitude. For waste dumpsites,   methane levels measured ranged between 45 ppm and 1220 ppm aligning with variation in the amount of waste. These higher   concentrations are, however, often found at low altitudes below 20 m over both dump sites. At temperatures above 30 °C, methane   concentrations are found at its highest across both dumpsites. Also, while waste dumpsites seem to emit more methane than rice farms,   all study sites emitted appreciable amounts of methane which could accumulate and contribute significantly to regional climatic   variations and enhance levels of tropospheric ozone. This study concluded that the bespoke measuring unit performed relatively well,   and air temperature has a positive influence on methane concentration at all study sites.