Characteristic of phosphorus release with the control of pH of sediments from Meiliang Bay, Lake Taihu

Abstract

The phosphorus stored in the sediments can be released into the overlying water, acting as internal source for lakes. pH is one of the important factors influencing phosphorus release. In this paper, phosphorus fractions and the effect of pH on P release (48h) were investigated for the sediment from Meiliang Bay, Lake Taihu. The pH of the system was controlled with different buffer solutions. The release characteristics of phosphorus were influenced markedly by the pH condition. Specifically, acidity (pH=2.0) and alkalinity (pH=9.5, 11.8) conditions were more beneficial for phosphorus release than the neutral pH(pH=7.2) condition. The amount of phosphorus released from the sediments under alkalinity conditions (pH=9.5, 11.8) was about 4 folds than that in the acidity (pH=2.0, 4.6) and neutral condition when the release of phosphorus tended to be stable(14h). There had been distinct difference for the phosphorus speciation in the sediments of different simulation system. With the analysis to the phosphorus speciation of sediments after release experiment, it can be concluded that acidic condition can enhance Ca-bound phosphorus release, whereas alkaline condition can promote the release of Fe-bound phosphorus significantly. Fe-bound phosphorus is the key form of phosphorus release in Meiliang Bay of Lake Taihu. pH value is an important mechanism of influencing phosphorus content and eutrophication.