Asian aerosol transport to Alaska during ACE-Asia

Aerosols were collected at Adak Island, Alaska, one of the southernmost Aleutian Islands, and the Poker Flat Research Range, 30 km northeast of Fairbanks, Alaska, during the 2001 Aerosol Characterization Experiment-Asia Intensive Field Phase (March through April 2001). The size- and time-resolved aerosols were collected using three-stage DRUM aerosol sampling systems and analyzed for 42 elements between sodium and lead using synchrotron X-ray fluorescence. The results of these elemental analyses and back trajectory calculations clearly demonstrate the transport of Asian aerosols into Alaska and the sub-Arctic. In addition, the aerosols at Adak Island demonstrate that northern Europe and Russia are contributing to the aerosol composition, loading, and deposition over the North Pacific Ocean. The peak concentration of large (1.15 to 2.5 mm in aerodynamic diameter) soil aerosols at Poker Flat is 15% of that observed at Adak Island. If it is assumed that the same air mass is sampled at both sites and that deposition is the only aerosol removal mechanism, then this implies a large deposition of crustal elements to the marine and terrestrial ecosystems along the transport path. However, the observed concentration difference could be influenced by differences in transport path, the layered nature of Asian aerosol transport, and different vertical mixing properties over Adak Island and Poker Flat. Future work will examine the relative impacts of the above processes on the observed soil element concentrations.