南黄海溶解有机碳的生物地球化学特征分析

Analysis of Biogeochemical Characteristics of Dissolved Organic Carbon in the Southern Yellow Sea

依据1997—2003年每年1次的南黄海调查得到的溶解有机碳（DOC）数据，重点分析了2002年秋末冬初季节南黄海DOC的分布特征及其生物地球化学控制机制。结果表明，2002年秋末冬初南黄海表层海水DOC质量浓度为1．62～2．42mg／L，平均值为2．02mg／L，高于大洋的平均值，具有典型近海特征；南黄海DOC分布呈现北部高，南部低，在量值上，A断面〉B断面〉C断面，且有显著近岸高、远离海岸中部海区低的特点。近岸高值区主要受陆源输入影响，包括径流输入和人类活动两个方面，陆源输入相对生物生产过程更为重要；中部低值区主要受控干来自东海低DOC海流的冲淡作用。垂直方向上DOC质量浓度变化不大，这明显与南黄海海水混合较好有关。7a中南黄海DOC质量浓度总体上呈略微下降趋势，北部海域表现尤为明显，南黄海生物生产量的下降及近年来南黄海整体环境质量的提高是引起DOC下降的主要原因。

Based on the dissolved organic carbon （DOC） data collected in the southern Yellow Sea during 7 cruises from 1997 to 2003, the DOC distribution characteristics and biogeochemical control mechanisms in the southern Yellow Sea （SYS） in the winter of 2002 were emphatically analyzed. It is shown from the analysis results that the DOC concentration in the surface water of SYS in the winter of 2002 was in the range 1.62 to 2.43 mg/L with a mean value of 2.02 mg/L higher than that in the open ocean, and had a typical offshore feature; the DOC concentration in the SYS was higher in the north than in the south and was characteristic of high concentration in the nearshore area and low concentration in the central offshore area. The high DOC value in the nearshore area was affected mainly by the terrestrial inputs, including runoff and human activities, and the low DOC value in the central SYS was controlled mainly by the dilution effect of low DOC current from the East China Sea. The vartical variations in DOC concentration were slight because the seawater in the SYS was well mixed. The DOC concentration in the SYS in the 7 years generally showed a slightly decreasing trend, and the decreasing trend was more significant in the northern sea area. The main causes for the decrease in DOC concentration are the decrease in biomass and the improvement of environmental quality in the SYS in recent years.