Persistent organic pollutants (POPs) at Ross Sea (Antarctica)

The most significant findings on the presence of persistent organic pollutants (POPs) in the marine ecosystem at Ross Sea are presented. Seawater samples were collected in many sampling sites located in a large area of the Ross Sea during various Italian expeditions in Antarctica. Two classes of POPs were considered, namely polychlorobiphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). The results highlighted the presence of these compounds in seawater samples at a total concentration level of about 50 pg/l for PCBs, and 220 pg/l for PAHs. Moreover, seawater samples showed low to high molecular weight PAHs (LMW/HMW) and phenanthrene to anthracene (PHE/ANT) ratios higher than 1 and 5, respectively, which may suggest the predominance of a petrogenic source (i.e. petroleum product contamination). Results were also obtained on the POP depth profile in the water column at Cape Adere, where two water masses converge and mix, i.e. the Modified Circumpolar Deep Water (MCDW) and the High Salinity Shelf Water (HSSW). According to both the PAH and temperature profiles a two-fold higher PAH and PCB concentration was observed for MCDW samples with respect to HSSW. This result represents the first experimental evidence of the external input of pollutants in this area of the Ross Sea coming from the outer oceanic circulation.