Investigation into the phosphorus adsorption characteristics of river sediment

Excessive amounts of nutrients, particularly phosphorus, in waterbodies have been identified as the principal cause of eutrophication. Phosphorus inputs to the waterbody can take various forms but may be generally categorised into particulate and soluble forms. Effluents from municipal and industrial activities have high proportions of soluble phosphorus which is the form most readily available for algal growth. The paper presents some preliminary results from a laboratory investigation into the mechanisms of sediment uptake of soluble phosphorus under a range of static and dynamic conditions. The investigation aims to established a general description of the phosphorus adsorption characteristics of river sediments with specific consideration of the influence of the hydraulic and hydrologic parameters of the waterbody. Sediment uptake was found to be a major phosphorus sink. The rate of the uptake process is explained by a combination of chemical adsorption of phosphorus to sediment particles, diffusion of the phosphorus between the overlying water and the interstitial water and microbial uptake. The paper concludes with an outline of proposed on-going research which would include field testing of the model developed from the laboratory investigation.