Application of Phoslock^TM, an innovative phosphorus binding clay, to two Western Australian waterways: preliminary findings

Abstract

Phoslock^TM is a specially modified clay designed to permanently bind phosphorus in those situations where phosphorus (P) release from sediments is a main driver of algal bloom formation. Extensive laboratory and mesocosm trials have demonstrated the effectiveness of Phoslock^TM in binding sediment released P using less than a millimetre thickness of clay. Two full-scale applications were undertaken in the summer of 2001/2002 in the impounded riverine section of two estuaries along the coastal plain of south west Western Australia. Both rivers are subject to blue-green algal blooms in the summer months. Phoslock^TM applied in a slurry from a small boat reduced dissolved P in the water column to below detection limit in the few hours it took for the clay to settle and substantially reduced P efflux from the sediments during the course of the trial. The effect of P reduction on phytoplankton growth was clearly evident in the phytoplankton dominated Vasse River but was less clear in the alternating phytoplankton to aquatic plant dominated Canning River which is also subject to surface nutrient inputs.