The role of small, low density particles on the partition of selected PCB congeners between water and suspended matter (North Sea area)

Abstract

The dissolved and particulate suspended concentrations of five PCB congeners (with 3–7 chlorine atoms) in the Southern Bight (North Sea) are interpreted in terms of an equilibrium partitioning model. K d values for riverine/coastal samples generally increase with chlorine number of the congeners (K d = 10 4–10 6). Values are more than an order of magnitude larger at the low suspended matter concentrations offshore (< 1 mg·dm −3). This is interpreted in terms of the presence of different SPM fractions with different contents of PCB: a fraction consisting of low size/density particles carrying high contents of PCBs, dominates at low SPM concentrations. The contribution of particulate forms to the total PCB concentration per unit volume may, therefore, be significant even at low SPM concentrations.