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PHOSPHORUS STORAGE IN FINE CHANNEL BED<br />

SEDIMENTS<br />

DJ Ballantine 1a , DE Walling 1 , AL Collins 2b and GJL Leeks 2<br />

1<br />

Department of Geography, University of Exeter, Exeter, EX4 6RJ, UK, E-mail:<br />

Deborah.Ballantine@sepa.org.uk; 2 Centre for Ecology and Hydrology, Wallingford,<br />

Oxfordshire, OX10 8BB, UK; a Present address: SEPA, Carseview House, C<strong>as</strong>tle<br />

Business Park, Stirling, FK9 4SW, UK; b Present address: ADAS, Woodthorne, Wergs,<br />

Wolverhampton, WV6 8TQ, UK<br />

SUMMARY<br />

Deposition and storage of fine sediment on channel beds represent an important<br />

component of a catchment’s sediment budget and can have implications for<br />

sediment-<strong>as</strong>sociated phosphorus fluxes and concentrations through water-sediment<br />

interactions. Spatial and temporal variations in the phosphorus content and storage<br />

in fine bed sediment have been studied in two UK lowland catchments, the Rivers<br />

Frome and Piddle in Dorset. Fine bed sediment w<strong>as</strong> sampled in representative<br />

reaches on a bi-monthly b<strong>as</strong>is using a re-suspension cylinder, and the resulting<br />

samples were analysed for total phosphorus, a range of phosphorus fractions<br />

and particle size. The results demonstrate the spatial and temporal variability of<br />

sediment-<strong>as</strong>sociated phosphorus concentrations and storage, with maximum<br />

and minimum phosphorus concentrations and storage occurring in late summer<br />

and winter respectively. Temporal variations in concentrations reflect residence<br />

times of the sediment and ambient phosphorus concentrations, while variations in<br />

storage are mainly due to hydrological regimes. Spatial variations reflect catchment<br />

characteristics and the location of inputs. Overall, the study highlights the need to<br />

consider both spatial and temporal controls on phosphorus storage <strong>as</strong>sociated with<br />

fine channel bed sediments.<br />

202

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