Methane flux dynamics from urban canal systems under passive and controlled disturbance conditions | |
| Author | Ei Ei Phyoe |
| Call Number | AIT Thesis no.EV-23-17 |
| Subject(s) | Greenhouse gases--Environmental aspects Methane--Environmental aspects |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Greenhouse gases (GHGs) such as CO2, N2O, O3, CH4 and H2O have the property of absorbing the emitted infrared radiation from earth’s surface. Since the Industrial Revolution, huge amount of anthropogenic greenhouse gases (GHGs) have been emitted into the atmosphere, which is the primary cause of global warming. Among GHGs, methane has approximately 34 times higher heat retention capacity in a 100- year timeframe and 86 times higher in a period of 20 years, when compared to CO2. Methane, predominantly produced via methanogenesis by archaea, a terminal process of the degradation of anaerobic organic matter and natural wetlands are the main sources of biogenic methane emissions. The Ramsar Convention listed ditches and canals as man-made wetlands in a category of ‘canals and drainage channels or ditches’ (Finlayson, 2018). The increasing urbanization in need for waterway control and flooding buffers, the expansion of commercial mining activities and agriculture have resulted in a proliferation of small artificial water bodies in many parts of the globe. The small artificial water bodies are poorly quantified, and emission estimations are constrained by both data lacking on spatial extent and scarcity in direct flux measurements. These urban water environments can be considered as the understudied hotspots of microbial CH4 cycling because microorganisms may be more abundant in urban waters because of the combined sewer overflows or discharge from wastewater treatment plants. Therefore, in order to fulfill this current research gap, this study will mainly focus on methane flux dynamics from two urban canals which has two different characteristics (rainwater canal and wastewater canal) under two conditions (passive and disturbance conditions) within the campus of Asian Institute of Technology, AIT. In this study, passive methane emissions were observed with an average of 2.68 mg/m2.hr from rainwater canal and 10.9 mg/m2.hr from wastewater canal. During the sediment disturbance, rainwater canal released 3503. 89 mg/m2.hr of methane and wastewater canal emitted 3911.62 mg/m2.hr of methane from controlled sediment disturbance. There are significant differences between passive and disturbed conditions from both canal systems, which indicate the importance of methane release potential from sediments and impacts of disturbance in urban canals. In terms of yearly emissions, rainwater canal emits 23.5 kg.CH4/year while wastewater releases 528.98 kg.CH4/year from canal water surface. Therefore, wastewater canal is a more serious methane emission hot spot due to its large area occupation and high nutrient loading from wastewater effluent. When considering the seasonal changes on methane emissions, there are no significant differences in both passive and disturbed conditions between wet season and dry season. Therefore, methane emissions from urban canals are the year-round sources of methane emissions. Moreover, aeration and alternative wetting and drying to canal sediment significantly reduced the methane emissions according to 7-Day continuous disturbance study. |
| Year | 2023 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Cruz, Simon Guerrero |
| Examination Committee(s) | Ekbordin Winijkul;Xue, Wenchao |
| Scholarship Donor(s) | Loom Nam Khong Pijai (Greater Mekong Subregion) Scholarships |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2023 |