Phosphorus speciation of sediments from lakes of different tropic status in Eastern China

Information about the chemical composition of phosphorus (P) in sediment is critical for understanding P dynamics and eutrophication in lake ecosystems. Eutrophication as a result of P pollution still persists so we chose to determine the P characteristics of sediments from ten lakes of different trophic status and the relationships between P fractions and environmental factors. The results show that the Standards, Measurements and Testing (SMT) method combined with P-31-nuclear magnetic resonance (P-31-NMR) can efficiently show the P characteristics of sediment. Phosphorus concentrations in sediments decreased as the trophic status of the lake improved. Inorganic P (Pi) was the dominant form of total P (TP) in most of the lake sediments and was mainly comprised of HCl-Pi, a stable Pi fraction. Results of P-31-NMR analysis show that the extracts were dominated by ortho-P (36.4-94.8 %) and mono-P (4.0-36.2 %), with smaller amounts of diester-P (.6-23.1 %), pyro-P (.2-4.4 %), and phon-P (.3-.7 %). Analysis of the relationships between the P composition and the trophic status of the lakes indicated that the bioavailability of P forms has an influence on the surface water trophic conditions and the health of aquatic ecosystems.