RETENTION AND LONG TERM ACCUMULATION OF EOCl FROM PULP MILL EFFLUENTS IN A BALTIC SEA RECIPIENT

摘要

The total inventory and distribution of Extractable Organic Chlorine (EOCl) has been investigated in an estuary exposed to pulp mill effluents for over 50 yr. The estuarine turnover of suspended particulate matter (SPM) and associated pollutants was studied using a model describing important processes for EOCl accumulation. The recipient has a low retention of 5PM due to dominating stratified conditions in the water column. The total inventory of EOCl in the sediment is therefore relatively low as compared with the total discharge. It was found that the vertical distribution of EOCl has a close relationship to the extent of chlorine use at the mill. Discharges of SPM from the pulp production process play a major role in establishing the chronology of the sediment. A modernisation of the mill from 1986 to 1991 considerably reduced the discharges of chlorinated substances. In the near future there will be an accumulation of EOCl in the estuary.