First evidence of legacy chlorinated POPs bioaccumulation in Antarctic sponges from the Ross sea and the South Shetland Islands

Antarctica is no longer pristine due to the confirmed presence of anthropogenic contaminants like Persistent Organic Pollutants (POPs). Benthic organisms are poorly represented in contamination studies in Antarctica although they are known to bioaccumulate contaminants. Sponges (Phylum Porifera) are dominant members in Antarctic benthos, both in terms of abundance and biomass, and are an important feeding source for other or-ganisms, playing key functional roles in benthic communities. To the best of our knowledge, legacy chlorinated POPs such as polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and dichlorodiphenyltrichloroethane (DDT) and their metabolites have never been investigated in this Phylum in Antarctica. The aim of this work was to evaluate the bioaccumulation of PCBs, HCB, o,p'- and p,p'-DDT and their DDE and DDD isomers in 35 sponge samples, belonging to 17 different species, collected along the coast of Terra Nova Bay (Ade`lie Cove and Tethys Bay, Ross Sea), and at Whalers Bay (Deception Island, South Shetland Islands) in Antarctica. Lipid content showed a significant correlation with the three pollutant classes. The overall observed pattern in the three study sites was EPCBs>EDDTs>HCB and it was found in almost every species. The EPCBs, EDDTs, and HCB ranged from 54.2 to 133.7 ng/g lipid weight (lw), from 17.5 to 38.6 ng/g lw and from 4.8 to 8.5 ng/g lw, respectively. Sponges showed contamination levels comparable to other Antarctic benthic organisms from previous studies. The comparison among sponges of the same species from different sites showed diverse patterns for PCBs only in one out of four cases. The concentration of POPs did not vary significantly among the three sites. The pre-dominance of lower chlorinated organochlorines in the samples suggested that long-range atmospheric trans-portation (LRAT) could be the major driver of contamination as molecules with a high long range transport potential (e.g. low chlorinated PCBs, HCB) prevails on heavier ones.

Automated summary

Antarctic benthic organisms, especially sponges, have been found to bioaccumulate persistent organic pollutants (POPs). However, the role and contamination levels of sponges in Antarctica have been largely overlooked. This study evaluated the bioaccumulation of legacy chlorinated POPs in 35 sponge samples from different locations in Antarctica. The results showed that the overall contamination levels were comparable to other Antarctic benthic organisms, and the predominant contaminants were lower chlorinated organochlorines, indicating long-range atmospheric transportation as the main contamination pathway.