RELATIONSHIP BETWEEN CHLORINATED HYDROCARBONS AND ORGANIC-CARBON IN SEDIMENT AND POREWATER

Chlorinated hydrocarbons (PCBs and chlorinated pesticides) and organic carbon were measured in the bulk sediment, very fine, low density, sediment particles, porewater, and Hexagenia naiads of Lake Superior sediment to examine the distribution of the hydrophobic organic compounds and how this distribution is influenced by organic carbon. The porewater was divided into filtered and unfiltered fractions. The sediment fractions did not behave the same in their affinity to bind the chlorinated hydrocarbons, nor were all of the chlorinated hydrocarbons bound to the same extent. The affinity for most of the chlorinated hydrocarbons to the solids were in the order: larvae > fine particles > bulk sediment. The filtered porewater organic carbon (dissolved and/or colloidal) was about 1/2 to 2/3 as efficient as the bulk sediment organic carbon at binding these hydrophobic compounds. A three-phase (solid, porewater organic carbon, dissolved) competitive model estimates that < 10% of the chlorinated hydrocarbons in the porewater are dissolved. The remaining fraction is associated with the organic porewater colloids. © 1990, International Association for Great Lakes Research. All rights reserved.