Identification of sediment phosphorus release zones and its management in tropical hyper-eutrophic reservoir

Abstract

Abstract The water quality of the Krishnagiri Reservoir is deteriorating rapidly due to the release of high concentration of soluble reactive phosphorus (SRP) from the bottom sediments and consequent eutrophication in the reservoir. The main aim of this experimental study was to investigate the potential release rate of phosphorus from four different zones includes Riverine- R, Transition-Shallow - T (S), Transition-Deep - T (D), and Lacustrine zone in the reservoir and to find out the efficiency of oxygen to control over the release of phosphorus from sediments. Sediment samples were collected from four different zones of Krishnagiri Reservoir and the experimental study was conducted in the laboratory. This present study has identified that the Lacustrine zone of the Krishnagiri reservoir has got the high potential to release phosphorus (125.5 mg m-2 d-1). In addition the study found that the supply of oxygen to the sediments collected from the Transition-D zone during the summer season showed a significant control over phosphorus release and enhanced the sedimentation rate of phosphorus up to -2.4 mg m-2 d-1. This site-specific experimental study has identified that oxygen can efficiently manage the release of phosphorus from bottom sediment. Hence, aeration is potentially a promising method for the reduction of phosphorus release from the bottom sediments and better management of hyper-eutrophic condition in the Krishnagiri Reservoir.