Atmospheric dust concentration record from the Hercules Neve firn core, northern Victoria Land, Antarctica

Abstract

During the ninth Italian Antarctic Expedition, a 22 m deep firn core was drilled on the Hercules Neve (HN) in the Transantarctic Mountains, northern Victoria Land, Antarctica. The continuous dust record from HN, spanning 70 years from 1927 to 1994, displays sharp differences between the upper 15.5 m and the bottom part. The background of dust concentration in the upper part is quite homogeneous, with values around 6.5 x 103 particles g-1 of water, and some peaks reaching maximum values of 1.0-1.5 x 104 particles g-1 of water. In this part the volume-size distribution of particles shows a relative maximum around 0.9 μm, while a second maximum occurs for particles larger than 12 μm. The larger particles are likely to have a local origin, while the small-size component may be representative of long-range transport dust. Below 15.5 m the record shows higher values in both background and peak concentration, with mean values of 1.6 x 104 particles g-1. The volume-size distribution changes from 0.9 to 1.5 μm in parallel with the increase of dust concentration. The dust record suggests significant increases in concentration for the periods 1932-42 and 1951-64. It suggests some correlations with precipitation anomalies over South America and indirectly supports the hypothesis that small-sized dust at HN may originate from South America.