Phosphorus forms and distribution in Zhejiang coastal sediment in the East China Sea

Surface and core sediment samples were collected from Zhejiang coastal waters of the East China Sea to study phosphorus (P) forms and understand the potential release of P as well as adsorption. The sediments were extracted sequentially to determine four phosphorus fractions, and non-sequentially for total phosphorus (TP). The total concentration of phosphorus in the surface sediments ranged from 527.2 to 680.5 mg kg(-1). Inorganic P was the major form and accounted for 84-94% of TP. Among the four forms, P-Detrital was dominant (58.6-73.2%), followed by P-CDB (10.5-20.9%), P-Organic (6.1-15.9%), and P-CFA (5.9-16.3%). The distribution pattern of TP in the surface sediments was similar to that of P-Detrital and P-Organic, but different from P-CDB and P-CFA. A relatively high level of phosphorus was observed in estuarine sediments, reflecting the influence from terrestrial input. Phosphorus in all forms in core sediments at each station decreased with depth. In addition, potentially bio-available phosphorus accounted for 20-34% of TP.