Phosphorus release from lake sediments: Effects of pH, temperature and dissolved oxygen

Sediments can release Phosphorus (P) into overlying water under certain environmental conditions, which may have a significant impact on water quality and result in continuous eutrophication. We used laboratory experiments to evaluate effects of pH, temperature, and Dissolved Oxygen (DO) on P release from Lake Xuanwu, China. The results demonstrate that effects of pH on P release from sediments were distinct; more P was released under alkaline conditions than acidic conditions, but the least amount of P was released under neutral pH. Increasing temperature resulted in more release of P and a longer time to achieve equilibrium between sediment P release and P in overlying water. Influences of DO supply levels on P release were also quite significant; anaerobic conditions were more conducive to the release of P than aerobic conditions. Orthogonal experiments show that the 3 significant factors on P release from sediments were, in descending order, DO, temperature, and pH. These findings have important management implications for Lake Xuanwu.