Study of colloidal phosphorus variation in estuary with salinity

The variation of colloidal phosphorus with salinity in estuary was studied in this paper, which was compared with those of particle and truly dissolved phosphorus with the purpose of finding out the similarities and differences between their behaviors in the estuary. Distribution patterns of phosphorus in particle, colloidal and truly dissolved phase at different salinities and their relationships with suspended particulate matter were also studied to understand the transformation and transportation of colloidal phosphorus in estuarine area. The result showed that the concentrations of total colloidal phosphorus, organic colloidal phosphorus and inorganic colloidall phosphate all descended from river-end to sea-end, illustrating their terrigenous source. Ratios of organic to total colloidal phosphorus decreased with salinity's increment, indicating that organic phosphorus was influenced by scavenging process of colloid more significantly as compared with inorganic phosphate. Both of the phosphorus variation tendencies and the proportion between organic and inorganic phosphorus in colloidal phase was similar with that in truly dissolved phase while different from that in particle phase.