Colored dissolved organic matter (CDOM) is a part of total dissolved organic matter (DOM) and plays an important role in marine carbon cycling. Thus, a better description of the fates of CDOM may increase our understanding of DOM sources and sinks in marginal seas. This study aims to explore the distributions and possible controlling factors of DOM in the Taiwan Strait (TS) and the East China Sea (ECS) in the summer season.
The TS is a marginal sea of interest as it receives freshwater from both Taiwan Island and Mainland China and it also connects water transports between ECS, South China Sea (SCS) and Kuroshio water (KW). The concentration of DOM is slightly higher in the western side (China coast) than in the eastern side (Taiwan coast), and the highest concentration is always found in the Minjiang plume, revealing a significant impact of river discharge. The absorption and fluorescence properties of CDOM varied to a large degree with space arisen from the mixing of source waters including freshwater (from Taiwan and Mainland China), Changjiang diluted water (CDW), SCS water and KW. The KW and river-plume waters (Changjiang, Minjiang) have the lowest and highest values for absorption coefficient (a(325)) and fluorescence intensity of terrestrial humic-like CDOM (Ft: Ex/Em= 320-360/420-460), respectively. Both a (325) and Ft correlated inversely with salinity. Although the spectral slope (S) varied only within a small range, it still can be used to differentiate water masses in TS, as the S value is generally lower in coastal waters than in SCS and KW. Meanwhile, Ft is highly correlated with surface DIN and Si in TS, showing that these parameters are strongly influenced by terrestrial inputs.
There are six types of water masses mixing in the ECS in summer named CDW, Yellow Sea water (YSW), China coastal upwelling water, KW, Taiwan Strait Warm Current (TSWC) and Kuroshio upwelling water. Generally, the concentrations of DOC, DON and DOP are the highest in the surface water and decrease with depth due to strong degradation below the surface. The DOC/DOP and DOC/DON ratios of the most stations are higher than the Redfield ratio, showing a carbon enrichment of DOM in the ECS. The optical properties of CDOM show particular DOM characteristics in different water masses and reveal clearly the sources of DOM over various zones. After the operation of Tree-Gorges Dam, the CDW covering zone is likely reduced as reflected from the spatial patterns of salinity and absorption coefficient. The factor analysis implies that the terrestrial inputs and influence may be the dominant factor in constraining DOM and CDOM distributions in the TS and ECS.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0729109-151524 |
| Date | 29 July 2009 |
| Creators | Lu, Wan-tzu |
| Contributors | Gwo-ching Gong, Jia-jang Hung, Kuo-tung Jiann |
| 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-0729109-151524 |
| Rights | withheld, Copyright information available at source archive |
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