Estuary-enhanced upwelling of marine nutrients fuels coastal productivity in the U.S. Pacific Northwest
Estuary-enhanced upwelling of marine nutrients fuels coastal productivity in the U.S. Pacific Northwest
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DOI：
10.1002/2014jc010248
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发表时间：
2014-12-01
影响因子：
3.6
通讯作者：
Hickey, Barbara M.
中科院分区：
文献类型：
--
作者：
Davis, Kristen A.;Banas, Neil S.;Hickey, Barbara M.
太平洋西北陆架是加州海流系统中生物生产力最高的地区。采用物理-生物地球化学耦合模型研究了淡水输入对PNW陆架水域生产力的影响，采用真实的后预报和忽略哥伦比亚河和Juan de Fuca海峡(Salish海河口出海口)的模型实验。从海峡流出的氮是PNW大陆架的关键氮源--在上升潮季节，几乎占温哥华岛大陆架初级生产力的一半，华盛顿大陆架生产力的三分之一，俄勒冈州大陆架生产力的五分之一。哥伦比亚河对浮游植物的重新分布有区域性影响，但对PNW生产力的影响不像萨利什海那么大。区域营养平衡显示，流出海峡的氮几乎全部(98%)来自海洋--从深处涌入海峡，通过潮汐混合进入表层水域，然后返回沿海海洋。从沿海真光带氮素有效性的角度来看，由淡水输入Salish海驱动的河口环流比河流提供的陆源氮更重要。从海峡流出的富含氮的表层水主要有两条路径--在温哥华岛沿岸流中向西北方向移动，以及向南向华盛顿和俄勒冈州的大陆架移动。从胡安德富卡海峡和涡旋地区到这些大陆架的氮通量与当地风力驱动的上升流的通量相当。
The Pacific Northwest (PNW) shelf is the most biologically productive region in the California Current System. A coupled physical-biogeochemical model is used to investigate the influence of freshwater inputs on the productivity of PNW shelf waters using realistic hindcasts and model experiments that omit outflow from the Columbia River and Strait of Juan de Fuca (outlet for the Salish Sea estuary). Outflow from the Strait represents a critical source of nitrogen to the PNW shelf-accounting for almost half of the primary productivity on the Vancouver Island shelf, a third of productivity on the Washington shelf, and a fifth of productivity on the Oregon shelf during the upwelling season. The Columbia River has regional effects on the redistribution of phytoplankton, but does not affect PNW productivity as strongly as does the Salish Sea. A regional nutrient budget shows that nitrogen exiting the Strait is almost entirely (98%) of ocean-originupwelled into the Strait at depth, mixed into surface waters by tidal mixing, and returned to the coastal ocean. From the standpoint of nitrogen availability in the coastal euphotic zone, the estuarine circulation driven by freshwater inputs to the Salish Sea is more important than the supply of terrigenous nitrogen by rivers. Nitrogen-rich surface waters exiting the Strait follow two primary pathwaysto the northwest in the Vancouver Island Coastal Current and southward toward the Washington and Oregon shelves. Nitrogen flux from the Juan de Fuca Strait and Eddy Region to these shelves is comparable to flux from local wind-driven upwelling.