Distribution of Dissolved Organic Carbon in the Continental Margin off Northern Taiwan

臺灣北部邊緣海域溶解性有機碳之分佈

洪佳章(Jia-Jang Hung)；林柏齡(Po-Ling Lin)

Dissolved organic carbon ； Continental margin ； Kuroshio ； Northern Taiwan

Terrestrial, Atmospheric and Oceanic Sciences

6卷1期（1995 / 03 / 01）

13 - 26

英文

Analytical precision of dissolved organic carbon (DOC) in seawater using the high-temperature catalytic method (HTCO) and distributions of DOC in the continental margin off northern Taiwan were investigated. The DOC concentration of Kuroshio water off northeastern Taiwan varied from 122-136μM C at the surface to 65-74μM C at the bottom. The concentration decreased sharply downward in the upper 200m of the water column and then decreased slightly toward the bottom. The pattern showed neither seasonal variation nor a significant difference from that observed in the water off southeastern Taiwan. The concentration of DOC was found to be inversely correlated with apparent oxygen utilization (AOU) in the Kuroshio water. The slope, however, was smaller than that predicted from the Redfield stoichiometry, indicating that only a small fraction (＜25%) of AOU was derived from the oxidation of DOC. Distributions of DOC were found to vary, both temporally and spatially in the continental shelf and slope waters. Although the distributions were relatively patchy in the inner and middle shelves, they were influenced apparently by the upwelled Kuroshio subsurface water in the outer shelf and slope regions. DOC may have been diluted in the intensive upwelling regime but enhanced on the margin of the up- welling center. Terrestrial DOC was largely confined to areas close to the continent. DOC was higher in near bottom waters, indicating that it diffused from sediments and/or was released from resuspended sediments. Thus, DOC varied non-conservatively across the continental margin through various blogeochemical processes. The horizontal gradient of surface DOC decreasing from the southern East China Sea (ECS) to the N. Pacific may reflect a similar trend of surface biological productivity and suggest the potential export of DOC out of the ECS continental margin as well.