Abstract

Phosphorus (P) is the most vital nutrient that regulates primary production and determines the trophic state of freshwater bodies. However, the concern over dwindling stock coupled with the consequences of eutrophication of water bodies due to enrichment of nutrients has been increasing worldwide. P is a very essential macronutrient required to meet the global food demands and to ensure food security in the future. The present study (i) reviews the global phosphate demand, (ii) assesses the extent of pollution in Varthur lake in Bengaluru district of Karnataka, (iii) causal factors of foam formation in lakes and (iv) suggest measures to mitigate eutrophication. The sustained inflow of untreated or partially treated sewage to water bodies (lakes) has led to enrichment of nutrients. The physicochemical analysis of foam and lake water revealed that foam consists of higher concentrations of chemical contaminants and nutrients than the lake water. The external and internal loading of phosphates in lakes stimulated foam formation, profuse growth of macrophyte and eutrophic conditions. Biomonitoring revealed that only pollution tolerant phytoplankton and zooplankton dominated the lake. India has limited rock phosphate resources and is the largest importer of phosphates. Hence, there is an urgent need to (i) restrict phosphate use in detergents manufacturing and (ii) explore cost-effective viable alternatives in order to minimize the dependency on imports of mined phosphorus. This study will help different stakeholders to implement prudent management strategies to prevent urban lakes from eutrophication.

Keywords: Lake, Eutrophication, Foam, Plankton, Phosphorus, Pollution, Water quality