PHOSPHORUS DYNAMICS IN A LOWLAND RIVER

Seasonal changes in the concentration of phosphorus and other nutrient s along a section of the river Wey in southern England are reported. M easurements of the water chemistry upstream and downstream of a point- discharge together with the analysis of surface bed-sediments indicate s the accumulation of phosphorus in surface sediments in the spring an d 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 Elovic h equation End a parabolic equation. The model utilizes results from m easurements of the uptake of phosphorus by bed-sediments in a laborato ry 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 th an expected from the uptake by the bed-sediment alone. The net phospho rus uptakes measured in the summer and autumn surveys are much less, a nd in closer agreement with the simulated data. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.