Trace elements and individual particle analysis of atmospheric aerosols from the Antarctic peninsula

Abstract

Atmospheric aerosols were sampled continuously since December 1985 at the Brazilian Antarctic Station ‘Comandante Ferraz’ (62°05′S; 58°23.5′W) on the King George Island, Antarctic Peninsula. Stacked Filter Units (SFU) were used to collect fine ( d p 10 was measured by particle-induced X-ray emission (PIXE) analysis. This yielded data for the concentration of 23 elements: Na, Mg, Al, Si, P, S, CI, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Zr and Pb. The fine and coarse aerosol mass concentration was determined by gravimetric analysis. Absolute principal factor analysis (APFA) was used to obtain the aerosol elemental source profiles. Non-sea-salt sulphate showed a clear seasonal pattern, with minimum during wintertime. For summer and wintertime coarse particles, only two factors were significant, with the first having high loadings for Na, Mg, Cl, S, Sr, K, Ca, and the coarse particle mass concentration (representing sea-salt aerosol). The second factor had high loadings for Al, Si, Fe, Ti, and Ca (soil dust aerosol). For the fine mode particles three factors were differentiated, and they represented sea-salt aerosol, soil dust and sulphates. The sea-salt source profile agreed with the average sea-water elemental composition to within 20% for the elements Na, Mg, S, Cl, K, Ca and Br. The source apportionment for the coarse particle mass concentration (CPM) revealed that 86 to 89% of the CPM is accounted for by the sea-salt aerosol component, and 3.2 to 6.8% by soil dust and that 7.6 to 8.1% of the CPM could not be apportioned. For the fine particle mass concentration (FPM), sea-salt aerosol accounted for 60%, sulphates for 24 to 31%, soil dust for only 0.5 to 1.3%. The concentration of some trace elements like Cr, Ni, Cu, Zn, and Pb appeared too high, maybe due to long range transport of polluted air masses, or regional air pollution sources in the Antarctic peninsula. These data were not used in the calculations. Individual particle analysis by Electron Probe X-Ray Microanalysis (EPMA) showed a variety of particle types. The 17708 particles from 35 fine mode samples could be clustered in 9 groups: NaCl, CaSO 4 , CaSO 4 + NaCl, CaSO 4 + MgCl 2 , S, Si + NaCl, soil dust, MgCl 2 , pure Si. A significant number of NaCl and MgCl 2 particles showed small amounts of sulfur, possibly indicating reactions of these particles with gaseous sulfur compounds. Internal mixtures of silicates and marine aerosol particles were observed. Most of the sulfur in particles larger than 0.1 µm was in the form of CaSO 4 , and the abundance of these particles showed a seasonal variability with maximum in summer. DOI: 10.1034/j.1600-0889.1992.00010.x