Downstream changes in the transport and storage of sediment-associated contaminants (P, Cr and PCBs) in agricultural and industrialized drainage basins

Samples of suspended, floodplain and channel bed sediment have been used to examine downstream changes in sediment-associated contaminant transport an d storage in contrasting rivers in Yorkshire, UK. The concentrations of pho sphorus, chromium and selected PCBs associated with sediment in the River A ire and its main tributary, the River Calder, which drain an urbanized and industrialized catchment, are considerably higher than those in the relativ ely unpolluted River Swale, which drains an agricultural catchment. Concent rations of sediment-associated contaminants in the Aire/Calder system incre ase downstream, reflecting the location of urban and industrial areas in th e middle and lower reaches, and the location of point source inputs, such a s sewage treatment works. The contaminant concentrations associated with fl oodplain and channel bed sediment in the Rivers Are and Calder are high, pa rticularly in the lower reaches. This, combined with measurements of sedime nt storage on the floodplain and channel bed, indicate that significant sto rage of sediment-associated contaminants occurs in the Rivers Aire and Cald er. (C) 2001 Elsevier Science B.V. All rights reserved.