中文摘要：

根据2012年2、5、8和11月长江口4个季节航次综合调查资料，分析了长江口及其邻近海域溶解有机碳（DOC）时空分布特征，探讨了DOC分布与盐度、表观耗氧量（AOU）、化学耗氧量（COD）、叶绿素a以及颗粒有机碳（POC）间的关系。结果表明，2012年长江口区DOC的浓度范围在0．53～5．21mg／L之间，均值为1．86mg／L。DOC浓度秋季最高，夏季和冬季次之，春季最低。DOC空间分布整体呈现近岸高、远岸低的格局，高值区分布在口门内和近岸水域，外海区DOC浓度随着离岸距离的增加而逐渐降低。各季节DOC空间分布略有差异。DOC与盐度、COD以及POC的相关关系较强，与AOU和叶绿素口相关性较弱。2012年长江口有机碳以DOC为主，DOC对总有机碳（TOC）的平均贡献率为55．8％，其中冬季贡献最大（59．40A），其次为秋季（59．2％）和春季（55．3％），夏季贡献率最低（49．4G）。

英文摘要：

Based on 4 survey data in the Yangtze River Estuary during February, May, August and November 2012, the authers analyzed the temporal and spatial distributions of dissolved organic carbon （DOC）, and the relationship with environmental factors, including salinity, apparent oxygen utilization （AOU）, chemical oxygen demand （COD）, chlorophyll a, particulate organic carbon （POC）. The results showed that the concentration of DOC ranged from 0. 53 to 5.21 mg/L, with an average value of 1.86 mg/ L. In horizontal distribution, the higher concentration of DOC was found in the coastal waters, and decreasing trend of DOC content with increasing of offshore distance was defined. DOC concentration had highest level in autumn, followed by summer, and lower value of DOC was in winter and spring. Meanwhile, spatial distribution of DOC performed seasonal differences. The significant correlations of DOC with salinity, COD and POC were examined, while the weak correlations with AOU and chlorophyll a were provided. That indicated terrestrial input was the main source of DOC in the Yangtze River Estuary. DOC was the major constituents of the total organic carbon with an average contribution rate of 55.8% in the Yangtze River Estuary in 2012, and the maximum contribution rate （59.4%） was in winter, followed by in autumn （59.2%） and spring （55.3%）, and contribution rate in summer （49.4%） was significantly lower than other seasons.