Geochemical Forms of Phosphorus in Sediments of Three Large, Shallow Lakes of China

A sequential extraction method for the fractionation of phosphorus (P) in lake sediments was used to analyze phosphorus fractions of sediments taken from three large, shallow, eutrophic freshwater lakes of China-Taihu Lake, Chaohu Lake,and Longgan Lake. All three lakes are located in the lower reaches of the Changjiang River (Yangtze River). In Taihu Lake and Chaohu Lake, algae blooms occurred every year, while Longgan Lake was a macrophyte-dominated lake. Results showed that exchangeable phosphorus fractions were much higher in the eutrophic lake sediments than in the macrophyte-flourishing lake sediment. Also, the ratio of Fe:P in the sediments of the algae-predominant lakes was generally much lower than that in the macrophyte-predominant lakes. Thus, the geochemical fractions of phosphorus in sediments had a closer relationship with the type of aquatic vegetation.