a mesocosm study Nannaphat Niyomsri creator Cruz, Simon Guerrero Chairperson Ghimire, Anish Co-chairperson Ekbordin Winijkul Examination Committee Shanmugam, Mohana Sundaram Examination Committee Royal Thai Government Fellowship Scholarship Donor text series technical report th Pathum Thani, Thailand Asian Institute of Technology 2025 continuing eng

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121 leaves : ill.+ 1 online resource Rice production has been recognised as a significant contributor to anthropogenic CH4, a potent greenhouse gas with a Global Warming Potential (GWP) thirty-four times that of CO2 over a century and eighty-six times greater over two decades (Stavert et al., 2022). Anoxic conditions from continuous flooding with high organic content in soil promoted the activity of methanogenic archaea to produce and emit CH4 gas into the atmosphere. Conversely, methanotrophic bacteria are the biological methane sink by oxidizing CH4 to CO2. Metal micronutrients, including copper (Cu) and cerium (Ce), serve essential functions as cofactors for pivotal enzymes implicated in methane oxidation, particularly particulate methane monooxygenase (pMMO) and lanthanide-dependent methanol dehydrogenase (XoxF MDH). Nevertheless, studies focusing on methane emission flux from rice fields treated with metal supplements have been limited, and there is insufficient monitoring of CH4 emissions during the rice growth period. Therefore, this study addresses the current research gap by examining the effects of Cu and Ce on methanotrophs and methanogenesis in rice paddy fields through a mesocosm study and the analysis of soil physicochemical parameters and rice{u2019}s growth indicator. Results demonstrated that CH4 flux ranges from 18.70 to 2481.23 in units of mg.m-2.hr-1 for the control condition during the 120 days after transplanting. The metal treatments significantly reduced methane emissions throughout all rice growth stages compared to the control, particularly during the reproductive phases; the average methane flux decreased by over 80% under mixed conditions (Cu + Ce). Furthermore, the research on methane oxidation indicated that the presence of Cu and Ce improved methane consumption by over 60% during a 72-hour incubation period. Analysis of soil parameters indicated that metal amendments enhance nutrient availability, particularly nitrogen species, and simulated rice growth during the vegetative stage. 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, 2025 Greenhouse gases Atmospheric methane Environmental aspects Crops and climate Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B22996 http://203.159.5.9/ait-thesis/detail.php?q=B22996 251104 20260818095010.0