Author : Kathryn M. Hewett
Release : 2016
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Book Rating : 588/5 ( reviews)

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Dissolved Oxygen Dynamics in a Seasonally Closed Estuary in Northern California - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Dissolved Oxygen Dynamics in a Seasonally Closed Estuary in Northern California write by Kathryn M. Hewett. This book was released on 2016. Dissolved Oxygen Dynamics in a Seasonally Closed Estuary in Northern California available in PDF, EPUB and Kindle. The dissolved oxygen (DO) field in the Russian River estuary (RRE) was investigated during periods of mouth closure. The RRE is a bar-built, drowned-river-valley estuary located in northern California. Similar to other estuaries in Mediterranean climates, the mouth of the RRE closes episodically. The probability of closure is highest from September to November, when river flow is seasonally low, which allows sediment deposited by wave-driven processes to build a sand bar across the estuary mouth. Separation from the ocean leads to strong vertical stratification in the estuary, which impacts estuarine circulation and water properties. Of concern are the low oxygen concentrations observed in bottom waters during prolonged inlet closures. Based on 5 years of seasonal monitoring data, the pattern of oxygen distribution observed during periods of inlet closure is described and related to physical structure. The role of vertical mixing in controlling oxygen levels is then examined using a vertical 1-dimensional mass balance model. A strong pycnocline suppresses mixing, which is estimated from a vertical salt balance. The pycnocline thus also suppresses the diffusive flux of oxygen to the bottom layer, so that even low oxygen demand will eventually deplete dissolved oxygen in the water column. A one-dimensional mass balance model yields values for net ecosystem metabolism rates through the water column, showing net oxygen uptake beneath the pycnocline and net oxygen production in the photic zone above and within the pycnocline. Given the absence of mixing in the pycnocline, oxygen levels vary strongly between day and night – and most strongly during closure events when high levels of oxygen and chlorophyll are observed within the pycnocline.