Transport of mercury in the Arctic atmosphere: Evidence for a springtime net sink and summer-time source

In the Arctic, atmospheric concentrations of gaseous elemental mercury (GEM) can decrease strongly in spring when mercury is deposited to the snow. Some studies suggest mercury can accumulate in the snow while others suggest rapid reemission after atmospheric mercury depletion events. We have combined measurements of GEM at the Arctic site Zeppelin (Ny Alesund, Spitsbergen) with the output of the Lagrangian particle dispersion model FLEXPART, for a statistical analysis of GEM source and sink regions. We find that the Arctic is a strong net sink region for GEM in April and May, suggesting that mercury accumulates in the Arctic snow pack. For summer, we find the Arctic to be a GEM source, indicating reemission of previously deposited mercury when the snow and/or ice melts, or evasion from the ocean through sea ice leads and polynyas. Our results are corroborated by a related analysis of ozone source and sink regions. Citation: Hirdman, D., K. Aspmo, J. F. Burkhart, S. Eckhardt, H. Sodemann, and A. Stohl (2009), Transport of mercury in the Arctic atmosphere: Evidence for a spring-time net sink and summer-time source, Geophys. Res. Lett., 36, L12814, doi: 10.1029/2009GL038345.