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Title: Biogeochemical Controls on Phosphorus Cycling Between Sediment and Water in Estuaries
Author: K Prastka
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_153, Representation ID: 22, Object ID: 1502
The Joint Nutrient Study (JoNuS) was a Programme set up in response to international pressure to limit the risks of pollution due to excess nutrients entering the North Sea. Its purpose was to establish the nutrient status of UK Coastal Waters and was aimed at understanding nutrients in the southern North Sea, primarily in the Humber, Wash and Thames. This report covers the NRA funded Ph.D. at UEA which was a part of the JoNuS Programme. It provides some understanding of processes in estuaries, an essential feature of the JoNuS Programme. The primary goal was to assess the behaviour of phosphorus in the intertidal areas of the Wash system. Some of the work, including methodology, was described in progress reports. Experimental work focused on sediment samples from the Great Ouse and Nene estuaries, which drain to the Wash in Anglian Region.These studies demonstrated that passive diffusion studies such as conventionally used in studies of fluxes from sediments, may not adequately mimic the environmental situation in intertidal systems since the regular tidal excursions can actively force exchange of overlying and pore waters at rates that could be 10 times those predicted from molecular diffusion. In the case of phosphorus, this active “tidal pumping” probably acts to increase the rates of diffusion of oxygen into the sediments and thus acts to retain phosphorus within the sediments rather than promote its release. Thus it seems likely that diagenetic processes within sediments can act to redistribute phosphorus within sediments but do not result in fluxes of DIP into the water column. If sedimentary phosphorus is re-suspended and transported to an area of low DIP, desorption will occur, resulting in a potentially large source of DIP to the water column. In the U.K. most estuaries are effective traps and hence this particulate export process may not represent an important source of DIP to coastal waters. However, in some estuaries such as the Great Ouse there is evidence that winter storm flows may flush particulate matter out of the estuary.
Publisher: Environment Agency
Subject Keywords: EstuariesWater pollutionWater qualityPhosphorusEnvironmental protectionSediment pollutionNutrientsBrackishwater environment
Extent: 32
Total file downloads: 285

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