Quantifying turbulent mixing and oxygen fluxes in a Mediterranean-type, microtidal estuary
Quantifying turbulent mixing and oxygen fluxes in a Mediterranean-type, microtidal estuary
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量化地中海型微潮河口的湍流混合和氧气通量
DOI：
10.1007/s10236-003-0037-8
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发表时间：
2003
期刊：
影响因子：
2.3
通讯作者：
J. Sherwood
中科院分区：
文献类型：
--
作者：
J. Sharples;M. Coates;J. Sherwood
在间歇性河口的封闭（夏季）和开放（冬季）状态下进行了实验，以确定负责盐跃层垂直混合的物理过程，并量化水层之间的氧和盐的垂直通量。在阻塞阶段，观察到一个两层结构，与微咸的表面层覆盖老海水。在一个深盆的风驱动的湍流混合是一致的测量表层湍流耗散，但在底层的耗散似乎是由内部seiching驱动。在浅水区的河口溶解氧的垂直通量的呼吸和底层水和沉积物中的有机物质的矿化的需氧量的指示。在河口的开放阶段的三层结构进行了观察，有一个新鲜的，河流衍生的表层，新的海水的中间层，和老海水的底层。在较浅的区域，表层湍流扩散与当时经历的强风一致。当海水到达上游深盆时，由于低的跨密度跃层氧通量无法补偿氧的利用，海水的溶解氧降低到非常低的值。至少有50%的跨密度跃层盐通量在浅水河段的开放河口的Holmboe不稳定性的驱动。
AbstractExperiments were carried out on an intermittent estuary during its closed (summer) and open (winter) states to identify the physical processes responsible for vertical mixing across the halocline, and to quantify vertical fluxes of oxygen and salt between water layers. During the blocked phase a two-layer structure was observed, with a brackish surface layer overlying old seawater. Within a deep basin the wind-driven turbulent mixing was consistent with the measured surface-layer turbulent dissipation, but the dissipation in the bottom layer appeared to be driven by internal seiching. In the shallow regions of the estuary vertical fluxes of dissolved oxygen were indicative of oxygen demand by respiration and remineralization of organic material in bottom water and sediments. During the estuary's open phase a three-layer structure was observed, having a fresh, river-derived surface layer, a middle layer of new seawater, and a bottom layer of old seawater. In the shallower regions surface-layer turbulent diffusion was consistent with the strong, gusty winds experienced at the time. The dissolved oxygen of the incoming seawater decreased to very low values by the time it reached the upstream deep basin as a result of the low cross-pycnocline oxygen flux being unable to compensate for the oxygen utilization. At least 50 % of the cross-pycnocline salt fluxes in the shallow reaches of the open estuary are suggested to be driven by Holmboe instabilities.