Occurrences and possible sources of persistent organic pollutants (POPs) in ice-free area soils in East Antarctica

Antarctica is widely regarded as a sink for persistent organic pollutants (POPs). However, there is a scarcity of data on the occurrence and spatial pattern of POPs in Antarctica, especially in the cold-xeric East Antarctica. Here, organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in soils from the Larsemann Hills, the second-largest ice-free area along East Antarctica, were investi-gated. It is shown that the main OCP contaminants were HCB, p,p'-DDD and delta-HCH (3.7-1522.3 pg g(-1), 38.2-2276.6 pg g(-1) and < LOD-570 pg g(-1), respectively). OCPs in soils were primarily caused by long-distance atmospheric transport, but local sources can be found in areas heavily impacted by local human activities. Among DDTs and HCHs, onlyp,p'-DDD and delta-HCH were detected, indicating that DDTs and HCHs have aged. For PCBs (14.1-993.4 pg g(-1)), low-chlorinated PCB congeners were found in soil samples far from the station areas (Zhongshan, Progress II, and Progress I), possibly due to long-range atmospheric transport, while high levels of high-chlorinated PCB were found in the soils inside the station area (Law Base) and close to the main road, possibly associated with local station activities. Among the measured PBDEs (81.8-695.5 pg g(-1)), BDE-209 was the most frequently observed species, and the low-BDE found in soil samples could be from BDE-209 photo-degradation. The majority of samples containing high concentrations of BDE-209 are concentrated in the station areas, implying that its source may be related to local station activities.