3-PHASE PARTITIONING OF HYDROPHOBIC ORGANIC-COMPOUNDS IN GREAT-LAKES WATERS

Great Lakes waters were freshly collected, innoculated with radiolabelled hydrophobic organic compounds and, after equilibration, separated into particle bound, dissolved organic matter bound and freely dissolved phases. In these ambient suspended matter (0.2-5 ppm) and dissolved organic carbon (1-6 ppm) media, the freely dissolved phase generally dominates and the amounts associated with dissolved organic matter rarely exceeds 5% for most compounds. Solubility controls the constituent distribution between particle bound and freely dissolved but plays a much smaller role in mediating the binding to dissolved organic matter. Differences observed in the binding to dissolved and particulate organic matter support the need to consider the distribution of constituents among three phases. Although the concentration and composition of the substrate changes significantly, there is no apparent seasonal effect on the distribution of compounds among the three phases in the Great Lakes. © 1990.