PCBs in Antarctica

In a large area of Victoria Land during the 1988–1989, 1989–1990, 1990–1991, and 1991–1992 Italian expeditions analyzed lake sediment and soil samples.
The mean PCB normalized concentration was 240 (pg/g)/ (m2/cm3) dry weight for lake sediments (CV 27%); and 130 for soils (CV 18%). The much higher PCB concentration in lake sediment is probably due to the nature of Antarctic lakes, which form during the deglacial season from ice melting waters that are rich in atmospheric particulate matter trapped in the ice matrix during its formation. Lake sediments and soil samples also showed a PCB content that did not change significantly among sampling stations (the 95% confidence intervals of 37 the mean value for each matrix included the concentration of all the samples analysed). This low and quite homogeneous PCB contamination of the area under study may rule out any direct source of PCB pollution in Antarctica.
More recently, the concentration of selected PCB congeners in samples of recent snow and firn collected during the austral summer 1993–1994 in seven snowfields throughout northern Victoria Land was determined. The pattern of PCB isomers in snow showed a predominance of lower chlorinated congeners and the pattern roughly reflects that reported for atmospheric PCBs at Signy Island and King George Island (Kallenborn et al, 1998; Montone et al, 2003) The sampling sites of surface snow throughout northern Victoria Land were located at different altitudes (from sea level to 3,000 m) and at varying distances from the sea, but total PCB concentration showed no significant spatial variations (range 0.28–0.73 pg g–1; mean value 0.52 pg g–1). Samples from a 2.5-m deep pit at the Hercules Névé collected in summer 1993–1994 and 1994–1995 showed slight higher total PCB concentration (1 pg g–1) in the deepest samples (presumably deposited around 1986-1988) than in surface snow (0.65 pg g–1). This result seems to corroborate previous findings and agrees with the general decreasing trend in POP concentration in the atmosphere of Antarctica and the sub-Antarctic islands during the 1980s and 1990s. The numerous studies performed on PCB congener patterns in Arctic air and snow show that their distribution is very similar, with lighter trichlorinated PCB homologues largely dominating the atmosphere and snow of northern sites.