Atmospheric deposition of current use pesticides in the Arctic: Snow core records from the Devon Island Ice Cap, Nunavut, Canada† Xianming Zhang, a Torsten Meyer, a Derek C. G. Muir, * b Camilla Teixeira, b Xiaowa Wang b and Frank Wania a Current use pesticides (CUPs) have been detected in the Arctic, even though there are no direct sources and their long range atmospheric transport potential is generally lower than that of legacy pesticides. Data on the deposition of CUPs in the Arctic are required to assess the impact of their global usage and emission. In this study, selected CUPs were measured in the layers of a snow pit sampled on the Devon Ice Cap, Nunavut, Canada. The oldest sampled layers correspond to deposition from the early 1990s. Dacthal and endosulfan sulfate were most frequently detected, with peak deposition fluxes of 1.0 and 0.4 pg cm 2 per year. While endosulfan sulfate was more abundant than its parent compounds in most years, endosulfan (sum of a and b isomers) was predominant in 2003 and 2006, which together with air mass backward trajectories suggests a possible origin from ongoing use in Eurasia. The interannual variation in CUP deposition fluxes could not be explained with annual variations in the extent of air mass origin over agricultural lands, suggesting that other factors, such as the interannual variation in pesticide use, play a role in affecting the long range transport of CUPs to the Arctic. The very high variability in the concentrations of CUPs in the horizontal layers of Arctic ice caps is most plausibly explained by the highly episodic nature of long range atmospheric transport and deposition. While this strong influence of rare events limits the suitability of ice caps as reliable records of historical trends in Arctic contaminant deposition with annual resolution, the presence of concentration peaks in the ice record is proof of the possibility of such transport and deposition. Environmental impact Quantitative information on the deposition of current use pesticides (CUPs) in the Arctic is important for assessing the impact of their global usage and emission. Snowpack acts as a reservoir for atmospherically deposited organic contaminants in the Arctic and plays an important role in the environmental fate and impact of the contaminants. In this study, using a snow pit sampled on the Devon Ice Cap, Nunavut, Canada, we inferred the atmospheric deposition history of semivolatile organic compounds from the early 1990s to the mid 2000s. Large interannual variations of the deposition uxes indicate a highly episodic nature of long range atmospheric transport and deposition. Introduction Pesticides are produced in high volumes and are extensively used in tropical and temperate agriculture. Although those in current use (CUPs) tend to be less persistent and bio- accumulative than many of the banned legacy pesticides, they have been detected in samples from the Arctic, 1–6 where they have never been produced and are not likely to have ever been used. Transport of semivolatile organic compounds to the Arctic is believed to occur mainly through the atmosphere. 7–9 Concerns related to the presence of CUPs in the Arctic arise, because as inherently toxic chemicals they may pose a risk to the local ecosystems. 5,10 The pesticides can deposit on Arctic surfaces via diffusive gas exchange and together with rain, snow and atmospheric parti- cles. 11 Snow, due to its highly porous structure and low pre- vailing temperatures, can effectively scavenge both gas phase and particle-bound chemicals from the air 12 and is thus believed to contribute signicantly to the atmospheric deposi- tion of semivolatile contaminants in the Arctic. 11 Aer deposi- tion, the snowpack can act as a reservoir for the contaminants. a Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada b Aquatic Contaminants Research Division, Environment Canada, Burlington, Ontario, L7R 4A6, Canada. E-mail: derek.muir@ec.gc.ca; Tel: +1-905-319-6921 † Electronic supplementary information (ESI) available: Figures showing concentrations in the snow segments in snow water equivalent, airsheds of the Devon Island Ice Cap sampling site for all investigated deposition years, and maps for the use of dacthal and endosulfan in the USA during the investigated deposition years. See DOI: 10.1039/c3em00433c Cite this: Environ. Sci.: Processes Impacts, 2013, 15, 2304 Received 16th August 2013 Accepted 7th October 2013 DOI: 10.1039/c3em00433c rsc.li/process-impacts 2304 | Environ. Sci.: Processes Impacts, 2013, 15, 2304–2311 This journal is ª The Royal Society of Chemistry 2013 Environmental Science Processes & Impacts PAPER Open Access Article. Published on 07 October 2013. Downloaded on 03/01/2016 14:43:39. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. View Article Online View Journal | View Issue