碩士 / 臺灣大學 / 地質科學研究所 / 98 / Recent studies showed that iodide is a biophilic species. When the organic matters decomposed, methane and I- will be generated and released. Variations of halogen concentrations (Cl-, Br- and I-) and ammonium (NH4+) in pore water of marine sediments of selected sites were studied to help understanding the fluid source and the pathway of sulfate reduction in the potential gas hydrate area of offshore SW Taiwan. According to the concentration profiles (I-, Br-, CH4, SO4-2, NH4+), we can classify those studied sites into four groups. In group-1, which represents background group, concentrations of CH4, I-, Br- and NH4+ show no clear variations with depth. In group-2, rapid reduction of sulfate and significant increase in NH4+ and/or CH4 are observed. In sub-group 2A, the concentrations of CH4, I-, Br- and NH4+ all increase with increasing depth; in 2B, except methane concentration all other species (I-, Br- , NH4+) increase with increasing depth. In group-3, CH4, I-, Br- and NH4+ all increase with increasing depth. Unlike group-2, NH4+ concentration increases faster than those in group-2. In group-4, the CH4 concentration increases at depth, while there are only very low I- , Br- and NH4+ concentrations. The category except group-1 indicated the mixing of in situ and deep source fluids.
Based on the stoichiometry ratio between sulfate consumption and DIC increasing from the profiles of the studied coring sites, we can summary the pathway of sulfate reduction for group-2 to -4 as followings: For group 2, which could represent the majority sites in offshore SW Taiwan, sulfate is mainly consumed by AMO process with methane from the depth. For group-3, sulfate is consumed by decomposition of local organic matters with very few fluid input from depth. For group-4, almost all sulfates are consumed by AMO process.
| Identifer | oai:union.ndltd.org:TW/098NTU05138008 |
| Creators | Hsiao-Chi Chen, 陳筱琪 |
| Contributors | 楊燦堯 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 80 |
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