Nutrient removal efficiency of lake wetlands: A case study of Sanshan Wetland in Lake Taihu, eastern China

Abstract

To understand the function of lake wetlands in nutrient removal efficiency, Sanshan Wetland in Lake Taihu was selected as the study region. Remote sensing, GIS techniques, field investigation, chemical analysis and hydro-dynamical simulation were integrated to analyze the effects of nitrogen and phosphorus nutrient retention of wetland in this study. Various forms of nitrogen and phosphorus in the Sanshan Wetland were analyzed. In 2014, the input of total nitrogen (TN) and total phosphorus (TP) were 549.45 t and 19.4 t, respectively. About 20.99 t TN and 4.52 t TP were removed by emerged plants harvest and floating plants salvages. Changes of TN and TP in Sanshan Wetland were 528.46 and 14.88t during the year, respectively. Ways of the nutrients output included several processes of phosphorus sunking, depositing, degradating and exchanging between the Sanshan Wetland and Lake Taihu. The wetland captures of TN and TP were 2723.56 and 102.48 kg/(ha·a), respectively. The sediment dredging and plant harvesting and refloating are good ways to improve the water quality in Sanshan Wetland. Hydrodynamic simulation results show that due to the construction of Sanshan Wetland, the flow directions have changed and the velocity currents reduced.