To assess the short-term trend of pollution by hexachlorobenzene (HCB), chlorophenols, and polychlorinated biphenyls (PCB) emitted to a marine environment, existing and former loads were estimated based on pollutant concentrations in water, blue mussels, and sediment, using partitioning calculations. The study included chemical analyses of organochlorines in sediment samples, caged mussels, and semipermeable membrane devices (SPMD) incubated in the water column and in the outflow from an adjacent plant in order to find out whether the high pollutant concentrations found in the superficial sediment corresponded to former or existing discharges. A comparison was made of hypothetical water concentrations calculated from values determined in SPMDs, mussels, and sediment, assuming equilibrium in the distribution of the pollutants between mussels and water or sediment and water. Sediment-derived water concentrations of HCB in the vicinity of the outlet were much higher than the water concentrations calculated from SPMDs or mussels, indicating that the discharges of HCB from a local source were strongly reduced during the past decade. It is concluded that partitioning calculations applied on analytical data from mussels and superficial sediment, when combined with SPMD data, make possible the detection of short-term changes of environmental loads of hydrophobic pollutants.
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