New insights on metals in the Arctic aerosol in a climate changing world

Ship traffic, population, infrastructure development, and mining activities are expected to increase in the Arctic
due to its rising temperatures. This is expected to produce a major impact on aerosol composition. Metals
contained in atmospheric particles are powerful markers and can be extremely helpful to gain insights on the different
aerosol sources. Thiswork aims at studying the sources of metals in the Arctic aerosol sampled at the Thule
High Arctic Atmospheric Observatory (THAAO; Greenland, 76.5°N 68.8°W).
Due to the particular composition of Greenlandic soils and to properties of other sources, it was possible to find
several signatures of natural and anthropogenic aerosols transported from local and long-range regions.
Arctic haze (AH) at Thule builds up on long-range transported aerosol mainly from Canada and Nord America.
From a chemical standpoint, this aerosol is characterized by a high concentration of sulfate, Pb, As and Cd and
by a La/Ce ratio larger than 1. The Ti/Al and Fe/Al ratios in the AH aerosol are lower (Ti/Al = 0.04 w/w; Fe/
Al= 0.79 w/w) than for local aerosol (Ti/Al= 0.07 w/w; Fe/Al = 0.89 w/w).
Conversely, aerosol arising from coastal areas of South-West Greenland is characterized by a high concentration
of V,Ni, and Cr. These metals, generally considered anthropogenic, arise heremainly fromnatural crustal sources.
In some summer samples, however, the V/Ni ratio becomes larger than 3. In particular, cases displaying this characteristic
ratio, as also shown by backward trajectories, are associated with sporadic transport to Thule of ship
aerosol from ships passing through Baffin Bay and arriving to Thule during summer.
Although further measurements are necessary to confirm the discussed results, the analysis carried out in this
work on a large number of metals sampled in coastal Greenland aerosol is unprecedented.