The effect of seasonal pack ice melting on the sea water polychlorobiphenyl contents at Gerlache Inlet and Wood Bay (Ross Sea-Antarctica)

The effect of seasonal formation/melting process of pack ice on the PCB lev el of sea water at Gerlache Inlet and Wood Bay (Ross Sea, Antarctica) was i nvestigated during four Italian expeditions, i.e. 1988-89, 1990-91, 1991-92 , and 1993-94. Surface sea water samples from Gerlache Inlet and Wood Bay b efore pack ice melting showed a typical total PCB concentration of 133 pg/l and 120 pg/l, respectively, which increased by a factor of about 1.3 in bo th sampling sites during pack ice melting. This effect was attributed to th e transfer of PCBs contained in the pack ice to sea water, and salinity was used as a tracer to verify this hypothesis. In this respect, pack ice and sea water samples were collected during the 1993-94 Italian expedition, and both salinity (S) and total PCB content were measured. A fairly good agree ment was observed between the experimental PCB concentration and the value calculated by the dilution model which was applied to the mixing process be tween sea and pack ice melting waters. Although this effect seems to be lim ited in time and space it is nevertheless significant because it happens du ring summer when biological species have their highest activity.