Phosphorus dynamics in a lowland river

Seasonal changes in the concentration of phosphorus and other nutrients along a section of the river Wey in southern England are reported. Measurements of the water chemistry upstream and downstream of a point-discharge together with the analysis of surface bed-sediments indicates the accumulation of phosphorus in surface sediments in the spring and summer followed by a decrease in the autumn and winter. The profiles of soluble reactive phosphorus (SRP) concentration along a stretch of river are modelled by simulating the net loss of SRP using the Elovich equation End a parabolic equation. The model utilizes results from measurements of the uptake of phosphorus by bed-sediments in a laboratory fluvarium channel. The channel was also used to measure the uptake of phosphorus and release from bed-sediments to overlying anoxic water. The measured net loss of SRP in the spring survey is much greater than expected from the uptake by the bed-sediment alone. The net phosphorus uptakes measured in the summer and autumn surveys are much less, and in closer agreement with the simulated data. (C) 1998 Elsevier Science Ltd. All rights reserved.