Quantifying the Fluxes of Atmospherically Derived Trace Elements in the Arctic Ocean/Ice System using 7Be

Aerosol deposition is an important pathway for delivering biologically-essential and anthropogenically-derived trace elements to the Arctic Ocean. Limited field study in the harsh Arctic environment has forced a reliance on poorly constrained models for the atmospheric deposition of trace elements. Here we use the cosmic ray produced radioisotope ⁷Be to link aerosol concentrations to flux to the Arctic water/ice system. Seawater, ice, snow, melt pond, and aerosol samples were collected during late summer 2011 as part of the RV Polarstern ARK-XXVI/3 campaign. The average ⁷Be aerosol loading was 0.018 dpm m^-3 and we determined an average ⁷Be flux of 125 dpm m^-2 d^-1, consistent with results from previous studies in the region. None of the lithogenic aerosol elements showed any significant enrichment above crustal composition, while the pollution-type elements showed varying degrees of enrichment relative to crustal values. In addition to our own measurements, we use two years of continuous aerosol ⁷Be and trace element data from the Alert (Canada) monitoring site to generate seasonal and annual estimates for the fluxes of ⁷Be and trace elements to the Arctic water/ice system. Fluxes of ⁷Be are 30% higher in Winter (Nov-May) than in Summer (Jun-Oct) due to the strong seasonality in aerosol ⁷Be concentrations. Fluxes of lithogenic elements (Al, Mn, Fe) are 2-3 times higher in Summer, possibly due to local dust sources on Ellesmere Island. Fluxes of V and Pb are strongly correlated and are 2-3 times higher in Winter, while fluxes of Ni, Cu, and Zn are relatively uniform for both seasons.