长江口泥质区的季节性沉积效应

Seasonal Sedimentary Effect on the Changjiang Estuary Mud Area

利用长江口泥质区及其邻近海域夏季和冬季的悬浮体、温度和盐度资料,就长江口泥质区悬浮体的季节性分布和沉积效应进行探讨。由于台湾暖流的强烈阻隔作用,夏季和冬季长江入海的泥沙基本滞留在123o15'E以西的内陆架进行搬运和沉积。长江入海沉积物供应量、台湾暖流、浙江沿岸流和长江冲淡水具有明显的季节性变化规律,致使长江口泥质区的沉积效应具有强烈的季节性,冬季沉积作用弱,夏季沉积作用强。该泥质区是长江入海沉积物的“汇聚区”,其中冬季的沉积物汇聚量显著小于夏季。长江口泥质区和济州岛西南泥质区的沉积过程变化都具有季节性,但有其各自的鲜明特色。

The seasonal distributions of suspended matter and their sedimentary effect on the Changjiang (Yangtze River) Estuary mud area (CEMA) were discussed, based on the three cruise data of total suspended matter, temperature and salinity collected in the Changjiang Estuary and its adjacent area in summer and winter. The results showed that the basic pattern of distributions of suspended matter in the CEMA and its adjacent area is almost the same in winter and summer. It is indicated that the sediments from Changjiang to the sea are almost trapped on the inner shelf west of 123 o 15'E, due to the strong obstruction of the Taiwan Warm Current (TWC), supporting that the sediments from Changjiang to the sea are mainly transported and deposited on the inner shelf. The sediment supply from Changjiang to the sea, TWC, Zhejiang Coastal Current (ZCC) and Changjiang Diluted Water (CDW) show a strong seasonal variation, resulting in the strong seasonal sedimentary effect on the CEMA. The sedimentation of this mud area is stronger in summer and weaker in winter. The CEMA is a 'sink' of the sediments from Changjiang to the sea. It is suggested that the amount of sediments deposited in this mud area in summer is much more than that in winter. The sedimentation processes of the CEMA and southwest Cheju Island mud area are characterized by a strong seasonal variation, but the processes of the two mud areas are very different. The sedimentation of the southwest Cheju Island mud area is stronger in winter and weaker in summer.