Abstract: Speciation of phosphorus in surface sediments which were collected during several CHINARE cruises in Prydz Bay were investigated. The sequential extraction method(SEDEX) was used to separate and quantify the following five sedimentary P reservoirs: exchangeable phosphorus (ExP), iron phosphorus (FeP), authigenic phosphorus (AuP), detritus phosphorus (DeP) and organic phosphorus (OP). DeP and AuP were the major types of phosphorus in surface sediments, with an average of 37.5% and 25.8% to total P. The obvious positive relationships between OP, AuP and OC, Sibio indicated that they might come from the same source which was mainly from marine biogenic matters. DeP could be observed positively correlated with Al and sandy sediments, which preferences land sources that might be carried by sea ice with current. It was shown that the content and distributions of P in sediments were majorly controlled by the sources of P, also included the grain size of sediments and other physical factors such as sea ice and current．ExP was controlled by grain size of sediments, while FeP was controlled by iron. In addition, either ExP or FeP was a small components in total phosphorus, only 8.9% and 6.5% respectively. Bioavailable phosphorus concentrated in the central and eastern region, with an average content of 37.2% to total P.

Key words: phosphorus, sediment, biogeochemistry, Prydz Bay, Antarctica