A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management

Thesis (M. Sc.) - Asian Institute of Technology, 2026

Methane is a potent greenhouse gas responsible for roughly one third of observed global warming, yet its production and biological attenuation across tropical microhabitats remain poorly understood, particularly in Southeast Asia. This study assessed methane emission fluxes and methane oxidation potential across four environments at the Asian Institute of Technology campus in Pathum Thani, Thailand, covering rice paddy, canal, wastewater treatment plant, and termite mound, using closed chamber methods and slurry incubation over 96 hours.Emission flux followed a clear ranking, with rice paddies highest at 335.55 mg CH4 per square meter per day, followed by wastewater discharge at 309.18, canal at 260.08, and termite mounds lowest at 157.67. Rice paddy emissions peaked sharply during the tillering and heading stages, reaching a maximum of 28,953 mg CH4 per square meter per day, highlighting that short-term measurements can substantially underestimate seasonal totals. Low termite emissions reflected the dry mound structure, which limited anaerobic activity despite moderate organic carbon.Methane oxidation potential was active across all sample types, with near-complete methane depletion observed in every sample 96 hours. Wastewater sludge recorded the highest oxidation rate while termite material recorded the lowest, though the difference was narrow. The lower per-gram rate in termite samples is likely a normalization effect of their dry matrix rather than reduced biological capacity.Overall, methane production and oxidation co-occur across diverse tropical microhabitats, governed by moisture, organic carbon, and redox conditions. These findings establish useful baseline data for Thailand and support more accurate national methane emission reporting across Southeast Asia.