| Summary: | Recent observations of Arctic temperature increases and ice/snow loss have highlighted the importance of defining pollutant pathways to the Arctic. Fresh snow samples collected at Alert, Nunavut, from September 2014 to June 2015 were analyzed for carbon species, major ions, and metals, and their concentrations and fluxes reported. Comparison with simultaneous atmospheric monitoring found dry deposition to be a dominant removal mechanism for several compounds over the winter while wet deposition increased in importance in the fall/spring, possibly due to enhanced scavenging by mixed-phase clouds. This unprecedented dataset provided an opportunity for a temporally-refined source apportionment of key snow impurities. The majority (73%) of the black carbon in snow, a light-absorbing compound critical to the Arctic radiative balance, was identified as the product of fossil fuel burning with limited biomass burning influence. Both depositional and sourcing analyses suggested the external mixing of black carbon, sea salt, crustal, and sulphate aerosols. M.A.S.
|
|---|