长江口表层沉积物有机碳分布及其影响因素

Distribution of the total organic carbon of surface sediment and its influence factors in the Yangtze River Estuary

根据长江口及其邻近海域2007年2、5、8、11月4个航次野外调查资料，系统地探讨了长江口表层沉积物总有机碳（TOC）的时空分布特征及其主要影响因素。结果表明，长江口及其邻近海域表层沉积物类型以细砂和粉砂为主。细颗粒泥沙主要分布在调查水域南部，北部海域以砂组分为主，沉积物组成和分布具显著的季节变化特征；长江口及其邻近海域表层沉积物TOC含量介于0．012％～1．589％，平均为0．524％。不同季节其空间分布特征不同；最大浑浊区域和东南外海区（122°30′E以西，31°31′N以北）表层沉积物TOC含量显著高于北部海域；沉积物粒度是影响长江口表层沉积物TOC的重要因素，水动力条件通过作用于沉积物组成变化影响TOC时空分布，TOC的高分布区位于长江冲淡水锋面与台湾暖流、黄海沿岸流混合处，分布范围随水动力条件季节变化而变化。

Based on the field survey data of four sailings in the Yangtze Estuary and the adjacent waters during February, May, August, and November 2007, the total organic carbon （TOC） temporal and spatial distributions of surface sediments in the Yangtze River Estuary （YRE） were discussed, and main influence factors of surface sedi- ments TOC were analyzed according to the physical, chemical and sedimentary features of the YRE. The results showed that the surface sediment in the YRE was mainly composed by fine sand and silt. Fine sediment mainly distributed in the southern of the survey waters. The main components of the north sea were sand. The sediment composition and distribution showed significant seasonal variations. The surface sediment TOC in the YRE was between 0.012% and 1.589%, with an average of 0.524%. Spatial distribution of TOC had season characteristics. The surface sediment TOC contents in maximum turbidity zone and southeast offshore area （122°30′Ewest,31°31′N, north of） were significantly higher than those in the northern waters. Sediment grain size was an important factor influencing the surface sediment TOC, and hydrodynamic conditions influenced spatial and temporal distri- bution of TOC by affecting on the sediment composition. The distuibution of TOC with high levels was located at the frontal edge of Yangtze River diluted water, mixing with the Taiwan Warm Current and the Yellow Sea coastal current. High distribution area of TOC seasonally varied with the hydrodynamic conditions.