The Phosphorus Content of Fluvial Sediment in Rural and Industrialized River Basins
Water Research 36 (2002) 685–701 The phosphorus content of fluvial sediment in rural and industrialized river basins Philip N. Owens*, Desmond E. Walling Department of Geography, School of Geography & Archaeology, University of Exeter, Amory Building, Rennes Drive, Exeter, Devon EX4 4RJ, UK Received 3 August 2000; received in revised form18 April 2001; accepted 9 May 2001 Abstract The phosphorus content of fluvial sediment (suspended sediment and the o63 mmfraction of floodplain and channel bed sediment) has been examined in contrasting rural (moorland and agricultural) and industrialized catchments in Yorkshire, UK. The River Swale drains a rural catchment with no major urban and industrial areas, and the total phosphorus (TP) content of fluvial sediment is generally within the range 500–1500 mggÀ1. There is little evidence of any major downstream increase in TP content. In contrast, fluvial sediment from the industrialized catchments of the Rivers Aire and Calder exhibits both higher levels of TP content and marked downstream increases, with values of TP content ranging from o2000 mggÀ1 in headwater areas upstreamof the mainurban and industrial areas, to values >7000 mggÀ1 at downstreamsites. These elevated levels reflect P inputs frompoint sources, such as sewage treatment works (STWs) and combined sewer overflows. The influence of STWs is further demonstrated by the downstream increase in the inorganic P/organic P ratio from o2 in the headwaters to >4 in the lower reaches. Comparison of the P content of suspended sediment with that of the o63 mmfraction of potential source materialssuggests that topsoil from upland moorland/pasture and from cultivated areas, and channel bank material are likely to be the main sources of particulate P (PP) in the River Swale and in the headwaters of the Rivers Aire and Calder.
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