Assessing levels of POPs in air over the South Atlantic Ocean off the coast of South America

Abstract

The occurrence of persistent organic pollutants (POPs) in the atmosphere of the near-coast South Atlantic Ocean was studied. Air samples were collected using a high-volume air sampler (filter and polyurethane foam) on board the Argentinean research cruise R/V Puerto Deseado (CONICET). Samples were analyzed for 50 polychlorinated biphenyl (PCBs), 22 organochlorine pesticides (OCPs) and 14 polybrominated diphenyl ethers (PBDEs). These POPs classes showed a trend of decreasing levels from near-shore to open ocean sites. OCPs and PCBs were in the same order of magnitude (2.71–87.1 pg/m3 and 9.56–130 pg/m3, respectively) while PBDEs levels were significantly lower (0.69–2.58 pg/m3). Dichlorodiphenyltrichloroethanes (DDTs), endosulfans, chlordanes, hexachlorocyclohexanes (HCHs) and heptachlors were between 0.20 and 17.8 pg/m3, while drines and hexachlorobenzene (HCB) were at lower levels (0.28–3.71 pg/m3). The most frequently detected PCBs were congeners 32, 28, 44, 52, 95, representing > 50% of the total. The PBDEs congener pattern was dominated by congener 209 (70%), followed by 47 and 99 (16% and 7%, respectively). Air parcel back trajectories for the study period provided few insights as trajectories mainly stemmed from the open ocean with limited inputs from continental sources. These results indicate that the concentration of POPs (namely PCBs, OCPs, and PBDEs) in air remain elevated in the near-shore environment and then drop-off substantially beyond a distance of about 400 km. This has implications for the loading of POPs and delivery to the marine environment in the near coastal zone.