TECHNIQUES FOR EXTRACTION OF DISSOLVED INORGANIC AND ORGANIC PHOSPHORUS FROM LARGE VOLUMES OF SEA-WATER

Studies of marine phosphorus biodynamics using cosmogenic P-32 as a radio-tracer necessitated the determination of its specific activities (P-32/P ratios) in the dissolved inorganic (DIP) and organic phosphorus (DOP) pools. Owing to the low atmospheric injection rate of P-32 atoms (ca. 6 x 10(-3) atoms cm-2 min-1), its analysis involves extraction of DIP and DOP from large volumes of sea water (> 1 m3). When this work was undertaken, no suitable methods were available for their extraction, especially from large volumes of sea water. Two techniques are presented, one for the exclusive extraction of DIP and the other for both DIP and DOP from up to several m3 of sea water. The extraction of DIP is based on the selective adsorption of DIP-molybdenum blue complex using a cation-form acrylic fiber. The total dissolved phosphorus is extracted efficiently by adsorbing it on to iron(III) hydroxide surfaces [iron(III) hydroxide-coated acrylic fiber], following a technique used earlier for the extraction of dissolved silicon and other trace elements from sea water.