Phosphorus in Antarctic surface marine sediments-chemical speciation in Admiralty Bay

This study describes the relation of the phosphorus chemical speciation in surface sediments with input processes in Admiralty Bay, King George Island, Antarctica. The sediments were analysed with a sequential extraction for phosphorus fractionation to measure: exchangeable P (P-exch), iron oxyhydroxide bound P (P-Fe), authigenic P (Auth-P), detrital P (Detrital-P) and organic P (P-org). The study revealed that Detrital-P (39-70%) was the main sedimentary phosphorus forms and Auth-P (40-54%) was the second largest pool. The average percentage of each fraction of P followed the sequence: Detrital-P (41%) > Auth-P (37%) > P-Fe (12%) > P-org = P-exch (5%). Spatial differences in grain size distribution were found. Silt and clay factions were predominant in the inlets, whereas sand and gravel were the main components in Central bay (unofficial name). Values were extremely low for organic carbon (< 0.30%) and total nitrogen (< 0.17%). Total sulfur was lower than 0.15%, except for Mackellar Inlet where values were 1%. The dominance of detrital apatite in the total sedimentary phosphorus demonstrates the importance of terrestrial inputs from ice melting in governing the abundance and speciation of sedimentary phosphorus in the Admiralty Bay sediments.