台湾海峡西南部海域春季悬浮体及沉积物来源与输运机制

台湾海峡作为连接东海和南海的重要通道,其悬浮体和沉积物的来源和输运格局非常复杂。2005年4~5月利用带有浊度传感器和荧光传感器的SD204型CTD对台湾海峡西南部海域627个站位的悬浮体特性进行了综合调查,并采集了底层沉积物。在室内分别利用英国Marlvern公司生产的Mastersizer 2000型激光粒度仪和德国ELEMENTOR公司生产的ELEMENTOR varioELIII型元素分析仪对表层沉积物进行了粒度分析和沉积物碳、氮含量测定,结果表明,台湾海峡西南部海域春季受粤东沿岸流、韩江冲淡水、九龙江冲淡水及台湾海峡混合水影响,其中粤东沿岸流在向北输运过程中影响强度逐渐减弱,韩江冲淡水影响范围较大,并且在西南季风的控制下向东北方向输运;长时间尺度的沉积物输运格局表明,近岸沉积物由岸向海输运,远海地区沉积物由海向岸输运,并且在汕尾南部海域、南澳岛东南部海域形成了沉积物的汇聚区,沉积物以陆源为主;表层沉积物的输运过程受控于区域内水团、悬浮体分布及运动格局;在春季上升流形成早期尽管叶绿素荧光值相对较低,但其对表层沉积物的输运过程起着非常重要的控制作用。

Sediment sources and transport patterns in the southwest Taiwan Strait in spring

The Taiwan Strait is a narrow passage connecting the broad and shallow East China Sea to the deep South China Sea, with multiple sources and various transport patterns of sediments (including suspended matter and bedload). A comprehensive investigation has been carried out in the southwest Taiwan Strait in April and May 2005, at 627 stations with SD204 CTD, Seapoint turbidity and fluorescence profiling and collected surfacial sediment. Sediment samples were analyzed by using Mastersizer 2000 laser particle size analyzer (a product of Malvern, UK), and ELEMENTOR varioEL III element analyzer (a product of ELEMENTOR). Then sediment grain sizes, carbon and nitrogen contents were obtained. The results show that the southwest Taiwan Strait water is affected by the coastal currents along Guangdong, the diluted water from the Hanjiang River and Jiulong River and the mixed water of the Taiwan Strait. The coastal currents along Guangdong coasts decrease northward. The diluted water from Hanjiang River transports towards the northeast, which is controlled by seasonal southwest winds. The sediment transports offshore from coasts but onshore from the deep continental area. Thus, a sediment sink center is observed between the southern Shanwei coast and the southeastern Nan'ao Island, in which the terrestrial source dominates. The bedload transport pattern is controlled by the local hydrodynamics and suspended matter settling. The fluorescence of suspended sediment is low at early stage of the upwelling formation in spring. However, the upwelling plays an important role in the sediment transport processes.