Effects of biological activity, light, temperature and oxygen on phosphorus release processes at the sediment and water interface of Taihu Lake, China

Effects of biological activity, light, temperature and oxygen on the phosphorus (P) release processes at the sediment and water interface of a shallow lake, Taihu Lake, China, were investigated. The results show that organisms at the sediment and water interface can stimulate P release from sediments, and their metabolism can alter the surrounding micro-environmental conditions. The extent of P release and its effects on P concentration in the overlying water were affected by factors such as light, temperature and dissolved oxygen. The organism biomass increased as temperature increased, which was beneficial for P release. Dissolved total phosphorus (DTP) and dissolved inorganic phosphorus (DIP) concentrations in the corresponding overlying water were mainly controlled by light. P release occurred in both aerobic and anoxic conditions with the presence of organisms. However in the presence of light , P release in an anoxic environment was much greater than in an aerobic environment, which may stimulate alga bloom and result in an increase in total phosphorus (TP) in the overlying water. This information aids the understanding of P biogeochemical cycling at the interface and its relationship with eutrophication in shallow lakes.