Long-range Transport and Deposition of Current-use and Legacy Pesticides to Ice Caps on Svalbard, Norway

Transport and deposition of current use (CUP) and legacy pesticides (LP) and residual products to the Arctic from lower latitudes has been suggested in several studies. These observations show that some persistent and 'non-persistent' pesticides (with high atmospheric OH. reaction rates) are stable enough to be transported to and accumulate in a polar environment. In 2005, we drilled an ice core on Holtedahlfonna, a major ice field on Svalbard, Norway to measure the input of 47 CUPs and 17 LPs to a high-elevation abiotic environment. Svalbard has no native insects and no agriculture, so local use of pesticides is nil. Of the analyzed compounds, 9 CUPs and 10 LPs were observed in at least one of 6 core segments dating to 1953: 15 of these were found in enough core segments to reveal time-related trends. CUPs often observed included chlorpyrifos, dacthal, α- and β- endosulfan, endosulfan sulfate, trifluralin, and γ-HCH. Only chlorpyrifos and the endosulfans show increasing deposition over time. LPs most often observed included methoxychlor, α- and γ-chlordane, cis- and trans- nonachlor, endrin, dieldrin, and p,p-DDE. All of these, except p,p-DDE, show declining trends in the most recent sample (representing 1995-2005). In our comparison of core burdens at Holtedahlfonna and Austfonna (on Svalbard, 220 km ENE from Holtedahlfonna), we found twice as many CUPs at Austfonna along with greater amounts of dieldrin, methoxychlor, α-endosulfan and chlorpyrifos suggesting different deposition processes or sources. Air mass back trajectories over a10 year period of comparison between sites (1986-1995) show air mass flow from Eurasia 74% of the time to Austfonna and 45% to Holtedahfonna which likely accounts for some of the differences. Results from the Devon Ice cap (high Arctic Canada) in 2005 provide some rare, comparable data to Holtedahlfonna (1995-2005) for 5 CUPs and LPs, including chlorpyrifos, dacthal, lindane, trifluralin, and methoxyclhor. The deposition at Holtedahlfonna was higher in every case, and was ~20 times greater for dacthal and γ-HCH, ~100 times greater for trifluralin, and well over 1000 times greater for both chlorpyrifos and methoxychlor. These results clearly show that contaminant delivery from lower latitudes to the Arctic is geographically variable, and that Svalbard is being impacted to a much greater degree than parts of high Arctic Canada.