Classes of dissolved and particulate phosphorus compounds and their spatial distributions in the water of a eutrophic lake: a 31P NMR study

Knowledge of phosphorus (P) components in water is vital to understanding the biogeochemistry of the P cycle, but little information is available about P, especially organic P components in water. We used solution 31P nuclear magnetic resonance technology (31P NMR) to characterize the classes of dissolved and particulate P compounds, as well as their spatial variation, in eutrophic Lake Taihu, Eastern China. Results showed that orthophosphate and monoesters were the dominant components in dissolved and particulate P. The main difference between the classes of dissolved and particulate P compounds was that phosphonate was detected in dissolved P, whereas pyrophosphate was mainly found in particulate P. The proportions of various classes of P compounds in particulate total P were relatively stable, which may be partly attributed to phytoplankton. In dissolved total P (DTP), the proportions of orthophosphate and monoester varied substantially and were significantly correlated with DTP concentration. According to the source of P and the ratios of dominant classes of P compounds in dissolved and particulate P, the dissolved orthophosphate may be substantially influenced by pollution sources, and other P compounds are mainly controlled by biological transformation processes.