Methane (CH4) is not only important but also a long-lived greenhouse gas. Scientists estimated that more than half of CH4 is released from the water column. Studies of methane from water column are almost focused on rice fields, wetlands and swamps in Taiwan. There are only limited studies of methane about rivers, lakes and coasts. So this study investigated CH4 distribution in natural waters on and around Taiwan.
The average surface methane concentration in the South China Sea (SCS) is about 5.10¡Ó3.61 nM (n=103). The average surface methane concentration in the West Philippines Sea (WPS) is about 3.44¡Ó3.89 nM (n=56), lower than in the SCS. The average surface concentration in the Northern and Southern Taiwan Strait are, respectively, 4.72¡Ó3.19 nM (n=64) and 4.01¡Ó3.19 nM (n=51), and are between the average concentrations in the SCS and the WPS. The sea-to-air fluxes of methane in the SCS and the WPS are 0.38¡Ó0.99 £gmol/m2/h (n=103) and £gmol/m2/h (n=56), respectively. The sea-to-air fluxes of methane in the Northern and Southern Taiwan Strait are, respectively, 0.37¡Ó0.55 £gmol/m2/h (n=64) and 0.10¡Ó0.53 £gmol/m2/h (n=51). Although the sea-to-air fluxes for methane is much lower than the flux for carbon dioxide, methane emission in the SCS contributes nearly the same greenhouse effect as carbon dioxide does.
In Taiwan, the average surface methane concentration in rivers is about 3221¡Ó12386 nM, and the emission is about 104¡Ó337 (£gmol/m2/h) (n=179). The average surface methane concentration and flux are, respectively, 2164¡Ó5432 nM and 265¡Ó1289 £gmol/m2/h (n=120) in the water column in China, including the coasts of Hong Kong , Pearl River and Yangtze River. The average surface methane concentration and flux in the natural water are higher than in Taiwan.
In Asia, the average surface methane concentrations of the natural waters are, respectively, 8240¡Ó22753 nM (n=27) and 7639¡Ó24554 nM (n=50) in Thailand and Indonesia, twice the concentration in Taiwan. The average surface methane concentrations of the natural waters are, respectively, 2841¡Ó3358 nM (n=5) and 1939¡Ó3694 nM (n=15) in Malaysia and the Philippines, lower than in Taiwan. The emissions of methane in the natural waters are, respectively, 845¡Ó2622 £gmol/m2/h (n=50), 292¡Ó341 £gmol/m2/h (n=5) and 181¡Ó356 £gmol/m2/h (n=15) in Indonesia, Malaysia and the Philippines, also much higher than in Taiwan. The flux of methane in natural waters in Thailand (100¡Ó265 £gmol/m2/h, n=25) is as the same as in Taiwan.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0907110-160002 |
| Date | 07 September 2010 |
| Creators | Chang, Yu-chang |
| Contributors | Shu-Lun Wang, Yiing-Jang Yang, Jiann-Yuh Lou, Shang-Shyng Yang, Chen-Tung Arthur Chen |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0907110-160002 |
| Rights | campus_withheld, Copyright information available at source archive |
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