THE FORMATION OF SURFACE-ACTIVE ORGANIC-COMPLEXES OF COPPER IN COASTAL MARINE WATERS

The importance of surface-active organic matter on the speciation of c opper in coastal seawater was examined over a 22 month period in Massa chusetts Bay. Concentrations of copper associated with dissolved surfa ce-active organic matter ranged from 15 pmol/kg during winter (0.67% o f total dissolved copper) to 850 pmol/kg (18% of total dissolved coppe r) at the peak of primary production during a spring bloom and, follow ing a spring bloom, accounted for 36% of the total dissolved copper co ncentration. Association of copper with surface-active organic matter may have occurred by direct complexation with surface-active organic l igands or indirectly via organic-organic interactions with non-surface -active organic complexes of copper. Although total dissolved copper a t the site was inversely related to salinity, indicative of freshwater /continental sources, the amount of copper bound to surface-active org anic matter was significantly correlated with estimated rates of phyto plankton primary production (r(2) = 0.78). The primary source of surfa ce-active organically bound copper in Massachusetts Bay is apparently in-situ biological production and not export of anthropogenic/freshwat er ligands from continental sources. Although they represent a small b ut significant fraction of the total copper species present in coastal seawater, surface-active forms of copper assume added importance due to their active role in the transport and biogeochemical cycling of th is element.