Long-distance nutrient-transport process in the Changjiang river plume on the East China Sea shelf in summer
Long-distance nutrient-transport process in the Changjiang river plume on the East China Sea shelf in summer
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DOI：
10.1029/2007jc004248
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发表时间：
2008-04
影响因子：
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通讯作者：
A. Isobe;T. Matsuno
中科院分区：
文献类型：
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作者：
A. Isobe;T. Matsuno
[1]采用理想物理模式和生态数值模式相结合的方法，对夏季东海陆架区长江冲淡水（CDW）中的浮游植物水华现象进行了研究。特别要注意的是，尽管生物生产力高，但在几个月的时间内，浮游植物不会耗尽CDW中的营养物质。在本研究中，CDW表示为一个碗状的三层羽状运动在无限深的层，由于环境向东的电流。该模型允许地层露出海面。由营养盐、浮游植物和碎屑组成的最简单的生态系统模型与上述物理模型耦合。当河流羽流含有大量悬浮泥沙时，浑浊的河水可能会阻止阳光到达羽流的下层。因此，在混浊CDW的生态系统模型中，假设当一层被上层遮蔽时，初级生产力完全受到限制。当三层CDW被环境海流向东携带时，由于层与层的相互作用，羽状流以南的低层露出海面。释放到下层的营养物质在到达羽流以南的露头区域时用于初级生产，并导致那里的浮游植物大量繁殖。模拟的浮游植物浓度在最上层表现出类似的模式，在卫星获得的叶绿素a图像中观察到的高浓度的CDW向东延伸的南部。
[1] Idealized physical and ecosystem numerical models are coupled to investigate the phytoplankton bloom in Changjiang Diluted Water (CDW) on the East China Sea shelf in summer. Special attention is given to the phytoplankton not exhausting nutrients in CDW over a period of a few months in spite of high biological productivity. In the present study, CDW is expressed by a bowl-shaped three-layered plume moving on an infinitely deep layer due to ambient eastward currents. This model permits layers outcropping to the sea surface. The simplest ecosystem model composed of the nutrient, phytoplankton, and detritus is coupled with the above physical model. When river plumes contain a large amount of suspended sediment, it is likely that turbid river water prevents sunlight from reaching the lower layer of the plumes. Hence in the ecosystem model for turbid CDW, it is assumed that primary production is completely restricted when a layer is shaded by upper layers. As three-layered CDW is carried eastward by the ambient currents, lower layers south of the plume outcrop to the sea surface because of the layer-to-layer interaction. The nutrient released into the lower layers is used for primary production when it reaches the outcrop area south of the plume, and causes the phytoplankton bloom there. The modeled phytoplankton concentration in the uppermost layer exhibits a similar pattern to that seen in satellite-derived chlorophyll a images in which a high concentration is observed south of CDW extending eastward.