碩士 / 國立臺灣大學 / 海洋研究所 / 106 / Aerobic methanotroph is a group of microorganisms widespread in ground surface using methane as sole carbon source and oxygen as electron acceptor. Apparently, it plays an important role in controlling methane emitted from wetlands. However, the activity of aerobic methanotrophy regulated by temporal fluctuation of oxygen and methane supply in tidal wetlands is not well known. This study aims to examine the dynamics of methane fluxes and potential aerobic methane consumption rates in a tidal wetland of northern Taiwan, where the variation of environmental characteristics, such as sulfate and methane concentration in pore water has been demonstrated during a tidal cycle. Four field campaigns were carried out in December of 2016 and March, May and August of 2017. Methane fluxes, methane concentrations in surface sediments and oxygen profiles were measured at different tidal phases. Besides, batch incubations were conducted on surface sediments in order to quantify potential microbial methane consumption rates and to derive kinetic parameters for aerobic methanotrophy.
Our results demonstrated that the oxygen flux into the sediment during a tidal cycle was kept at a similar magnitude, which may infer a limited effect on the aerobic methane oxidation. Besides, the increase of pmoA gene abundance and potential aerobic methane oxidation rate didn’t always coexist with lower methane flux during a tidal cycle, suggesting that the methane flux was controlled by not only aerobic methanotroph but also methanogenesis. No similar pattern could be observed in terms of exposure time among three samplings of different tidal cycles, suggesting the exposure time is not the dominant factor. Weakly and moderately correlations could be found between the potential aerobic methane oxidation rate and either the methane flux or amount of pmoA gene, respectively, which indicated no specific factor could control aerobic methane oxidation and then regulate the methane emission during a tidal cycle. Besides, the sediment temperature was not the main factor affecting the activity of methanotroph and methane flux in a tidal affected wetland. Kinetic characteristics of aerobic methane oxidation were determined from the batch incubations. The maximum potential rate and the half saturation concentration were significantly different among the samples from different sampling campaigns, which inferred the metabolic capability of aerobic methanotrophs have changed through time beside of a tidal period. The interaction of microbes in Guandu wetland was complicated and the rule of aerobic methane oxidation on methane emission may be less significant during a tidal cycle.
| Identifer | oai:union.ndltd.org:TW/106NTU05279020 |
| Date | January 2018 |
| Creators | Tai-Yi Lee, 李岱怡 |
| Contributors | 王珮玲 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 67 |
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