Size distributions of atmospheric trace elements at dye 3, Greenland—II. Sources and transport

Abstract

Airborne concentrations and size distributions of 15 elements over the Greenland Ice Sheet have been measured during a one-month period in March 1989. The concentrations are relatively uniform, varying by less than a factor of three for virtually all of the elements. Notable exceptions are Na and Cl which vary by more than an order of magnitude; these differences can probably be accounted for by the link with transport from the oceans surrounding Greenland, although a significant fraction of the Na is of crustal origin in some samples.

The size distributions show strong peaks in the accumulation mode (0.4–1.0 μm) or the coarse particle mode (1.0–2.5 μm); some species show bimodal distributions with the presence of both modes. The aerosol chemistry and size distribution data are consistent with back trajectories and local weather conditions. For example, relatively high concentrations of Pb, Zn, Ni, Fe, and Mn in the accumulation mode during one of the runs are associated with trajectories from industrial regions of the Soviet Arctic. The elements Si, Al, Fe, K, Ca, Mn, and Ti in the coarse mode are believed to be dominated by crustal sources. However, some runs show the presence of an accumulation mode for most of these elements (with the exception of Al), suggestive of combustion sources. Overall, the results show that use of an impactor with several submicron size cuts combined with a suitable data inversion program can provide insights into the sources and transport of aerosols at remote locations such as the Greenland Ice Sheet.