Depth and temporal variability of organic carbon (POC) and total nitrogen (TN) and their isotopic compositions (£_13C and £_15N) in sinking particulate organic matter (POM) collected at the SEATS time-series station (18¢X15¡¦ N; 115¢X50¡¦ E), northern South China Sea, respond closely to the strong seasonality (changes in sea surface temperatures and mixed layer depths) in the surface layer, but are modified considerably by subsequent microbial degradation/remineralization and probably by re-suspension of sediments from the surrounding shelf region in the deep water. Lower C/N and £_15N in summer than the other seasons reflects the change of nutrient supply from NO3-rich, 15N-enriched subsurface waters to N2-fixation-dominated nitrogen source in the surface waters. Below the euphotic zone (>100m), both POC and TN decrease, whereas C/N increases progressively with depth owing to the biodegradation and the preferential removal of more degradable nitrogen-containing compounds through the water column. The C/N increase rate is estimated to be 0.4 unit per 1 km water depth, which is significantly higher than the world average (0.2/km) as a result of the input of higher C/N organic matter from sediments deposited nearby the SEATS site. POC and TN and total particulate mass fluxes decrease sharply within the euphotic zone and continue to decrease all way through the water column to seafloor. For site comparison and global synthesis, an average fraction (e-ratio) of 0.22 of POC exported from the euphotic zone and a POC attenuation rate (b value) of 0.97 are derived. Since the results of this study were obtained from a marginal sea characteristic of strong monsoonal modulation, they should contribute to a better understanding of the fate and pathway of POC in the world ocean.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0208110-232723 |
| Date | 08 February 2010 |
| Creators | Hsu, Chia-wei |
| Contributors | Hui-Ling Lin, Wen-Chen Chou, C.-C. Hung, David Der-Duen Sheu, T. Y. Tang |
| 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-0208110-232723 |
| Rights | off_campus_withheld, Copyright information available at source archive |
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