Species and bioavailability of phosphorus in surface sediments from the shoals in the Yangtze Estuary

Species and bioavailability of phosphorus in the sediments from the shoals in the Yangtze Estuary were investigated using the sequential extraction method. It was shown that total phosphorus in sediments varied from 437.6~1103.7 μg·g -1 and was mainly in the form of inorganic phosphorus dominated by detrital phosphorus. Inorganic phosphorus and organic phosphorus accounted for c. 79.5% and 20.5% of total phosphorus, respectively. It was also found that bioavailable phosphorus in sediments mainly included loosely adsorbed phosphorus, Fe bound phosphorus and organic phosphorus. Bioavailable phosphorus at the study area varied from 60.5~510.9 μg·g -1 and occupied c.28.9% of the sedimentary phosphorus pool.