Source identification of atmospheric particle-bound metals at Terra Nova Bay, Antarctica

Abstract

Environmental context The atmosphere above Antarctica, the cleanest part of the Earth’s troposphere, serves as a valuable laboratory for studying natural atmospheric processes and for monitoring the impact of human activities on the global environment. Central to these studies is an understanding of long-range transport of pollutants to Antarctica, and distinguishing the relative contribution of natural and anthropogenic sources. We use chemical tracers and isotopic analysis to assess the origin of metals associated with atmospheric particulates in Antarctica. Abstract During the 2010–2011 austral summer, size-segregated aerosol samples were collected at a coastal Antarctic site (Terra Nova Bay, Victoria Land) and analysed for major and trace elements and lead isotopic composition, in order to provide a better understanding of the sources of metals and their transportation pathways towards Antarctica. Aerosol size fractionation was performed by a cascade impactor, able to collect aerosol particles of aerodynamic diameter 10–7.2, 7.2–3.0, 3.0–1.5, 1.5–0.95 and 0.95–0.49µm. It was found that Al, Co, Fe, Li, Mn, Rb, Y and V were mainly related to crustal inputs, whereas the marine contribution was significant for Li, Mg, Na and Rb. An additional anthropogenic source influencing the concentration of Cr, Cu, Mo and Pb was clearly demonstrated. The concentration of the elements associated to the crustal and marine inputs showed high values in the coarse mode (7.2–3.0µm), whereas the anthropogenic elements were also characterised by a high concentration in the finer (1.5–0.95µm) particles. The study of the temporal trends of the measured chemical markers along with the meteorological variables revealed that both the crustal and anthropogenic elements were related to the air masses carried by the katabatic wind from the inland, whereas the marine input appeared to be higher in January when the sea-ice extent was reduced. Finally, lead isotope ratios pointed out that the anthropogenic input was likely related to the polluted aerosols from South America and Australia, representing the predominant fraction (50–70%) of the lead measured in the samples.