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Titel |
Impact of phosphorus control measures on in-river phosphorus retention associated with point source pollution |
VerfasserIn |
B. O. L. Demars, D. M. Harper, J.-A. Pitt, R. Slaughter |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1027-5606
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Digitales Dokument |
URL |
Erschienen |
In: Hydrology and Earth System Sciences ; 9, no. 1/2 ; Nr. 9, no. 1/2 (2005-06-14), S.43-55 |
Datensatznummer |
250006588
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Publikation (Nr.) |
copernicus.org/hess-9-43-2005.pdf |
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Zusammenfassung |
In-river phosphorus retention alters the quantity and timings of phosphorus
delivery to downstream aquatic systems. Many intensive studies of in-river
phosphorus retention have been carried out but generally on a short time
scale (2-4 years). In this paper, monthly water quality data, collected by
the Environment Agency of England and Wales over 12 years (1990-2001), were
used to model daily phosphorus fluxes and monthly in-river phosphorus
retention in the lowland calcareous River Wensum, Norfolk, UK. The calibrated
model explained 79% and 89% of the observed variance before and after
phosphorus control, respectively. A split test revealed that predicted TP
loads were in good agreement with observed TP loads (r2=0.85),
although TP loads were underestimated under high flow conditions. During
relatively dry years, there was no net export of phosphorus from the
catchment. High retention of phosphorus occurred, particularly during the
summer months, which was not compensated for, by subsequent higher flow
events. This was despite a relatively modest critical discharge (Q) above
which net remobilisation occur. Phosphorus removal from the effluent at two
major STWs (Sewage Treatment Works) reduced phosphorus retention but not the
remobilisation. This may indicate that the presence of impoundments and
weirs, or overbank flows may have more control on the phosphorus dynamics
under high flow conditions. Further phosphorus remedial strategies will be
necessary to prevent downstream risks of eutrophication occurring
independently of the unpredictable variability in weather conditions. More
research is also needed to quantify the impact of the weir and overbank flows
on phosphorus dynamics. |
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