PCBs and Chlorinated Pesticides in the Atmosphere of the Southwest Atlantic and Antarctic Oceans

The atmosphere content of a large number of OC compounds (HCB, HCHs, pp’-DDE, pp’-DDD, pp’-DDT and 11 PCB) was determined in a survey performed in November of 1995 in the open ocean between 23°S and 62°S. Air mass back trajectories were used to assess the origin of the air masses that arrived at the sampling point at low altitude. Organochlorine levels in the atmosphere ranged from not detected (<0.6) to 25.3 pg m-3 for HCB, 3.9–32.5 pg m-3 for ΣHCHs (α-HCH + γ-HCH), 3.7– 102.6 pg m-3 for PDDTs (pp’-DDT + pp’-DDD + pp’- DDE) and 46.2 up to 985.0 pg m-3 for PCBs. The trend is similar to that detected between New Zealand and the Ross Sea (January to March 1990). However the mean concentration of HCB (15 pg m-3) between latitudes 47°S and 62°S was remarkably lower than the values (60 pg m-3) found in 1993. The HCH concentration was 10 times lower than the data of 1987 The mean concentration of Lindane (8.8 pg m-3) was slightly higher than the value found along the transect from New Zealand to the Ross Sea, but three times below the values obtained in1992 and 1998 at Ross Island and Signy Island, respectively. In agreement with conclusions of other authors, the study showed the HCH and DDT levels were significantly decreased in recent decades.