Deposition of Polychlorinated Biphenyls to Firn and Ice Cores at Opposite Polar Sites: Site M, Dronning Maud Land, Antarctica, and Holtedahlfonna, Svalbard

Firn and ice cores from glaciers and ice sheets at polar opposite locations, Site M, Dronning Maud Land, East Antarctica (lat 75.00 S, long. 15.00 E), and Holtedahlfonna, Svalbard (lat 79.13 N, long. 13.27 E), were analyzed for 81 polychlorinated biphenyl (PCB) congeners in 75 chromatographic peaks. Both sites are remote at high elevations and receive contaminant inputs from long-range atmospheric transport (LRAT). Firn cores from Site M formed one sample covering 1958–2000, while the Holtedahlfonna site has a historic record in 6 samples from 1953 to 2005. Most congeners at both sites are in triCB, tetraCB, and pentaCB homologs, and at Site M, these comprise 89% of PCB and 83% at Holtedahlfonna (with variability over time). Site M PCBs are dominated by pentaCB (48%), while Holtedahlfonna (whole-core average) is dominated by tetraCB (45%). The dominant congeners in triCB through hexaCB homologs are the same at both sites (PCB-28 + 31, PCB-70, PCB-101, PCB-138). The total PCB flux at Site M (4.1 pg cm–2 yr–1) was ∼33% of Holtedahlfonna (12.7 pg cm–2 yr–1) over whole-core history, perhaps resulting from high UV during spring Antarctic stratospheric ozone depletion leading to PCB decomposition. LRAT frequency diagrams showed a limited range of sources to Site M, leading to a hypothesis about transport through the stratosphere. The LRAT diagram for Holtedahlfonna shows greater than 1% time-coverage areas through central and northern Europe and Russia over 52 years. There is no apparent quantitative trend to PCB deposition over time at Holtedahlfonna, similar to observations elsewhere in the Arctic.