Controlling eutrophication by enhancing purification capacity in lakes

To determine the potential for controlling eutrophication in lakes by controlling external pollutant loadings and through in-lake interventions, a dynamic model for total phosphorus (TP) and total nitrogen (TN) was derived. Based on data of Chinese lakes and of L. Okeechobee in the USA the threshold concentrations, i. e. concentrations above which algae blooms are formed, were determined as 0.035 mg/L for TP for both lakes and 0.35 mg/L for TN in Dianchi Lake and 1.050 mg/L for TN in Taihu Lake. According to the observed data the percentages of TP and TN loading that exceed the volume for maintaining the concentration in the lake that is lower than these thresholds and therefore would require nutrient control to prevent algae blooms are 78% (both for TP and TN) for Dianchi Lake in 1995, and 69% for TP and 56% for TN for Taihu Lake in 1987-1988. However, the financial requirements for construction of wastewater treatment plants and sewer collection networks, and for reducing non-point source nutrient loadings