A MULTIANNUAL EXPERIMENT ON TROPOSPHERIC AEROSOLS AT TERRANOVA BAY (ANTARCTICA) - ROLE OF PIXE ANALYSIS AND RELATED TECHNIQUES

In the framework of a multiannual research programme three summer samp ling campaigns (1990/1991, 1993/1994, 1994/1995) were undertaken at a coastal site (lat. 72 degrees 42'43 '' S, long. 164 degrees 06'58 '' E ) with a 12 h time resolution. Important topics of interest are associ ated with the roles of natural aerosols in the climatic system and bio geochemical cycles, as well as with aerosol transport, origin and inte ractions. Despite low concentrations, three basic techniques (a specia lly designed ''inertial impactor for Antartica'' (IIA); PIXE analysis; and multivariate statistical principal components analysis (PCA)) all owed (1990/1991 data) identification of two principal components (PCs) in the coarse fraction. ''Non-sea-salt sulphur'' and ''sea-salt'' aer osol dominated respectively the fine and coarse aerosol fractions. The 1993/1994 data are much more abundant (198 double samples) and the PI XE sensitivity was higher (systematic detection of Na and Mg). Prelimi nary results for the fine fraction, based on Na, Mg, Al, S, Ca and Fe, show the existence of three major PCs (interpreted as ''n.s.s. sulphu r'', ''sea-salt'' and ''crustal''), each element being highly and sign ificantly correlated to a particular PC. The addition of K does not ch ange the main properties of the PCs and K is associated with both PC 2 and PC 3. Strong Cl depletion is observed. S, Na and Al are convenien t tracers for obtaining continuous PC time distributions. A strong inc rease in S concentration is observed during the sampling period. Some short ''episodes'' are observed in all time distributions, possibly as sociated with aerosol transport phenomena. The 1993/1994 data and the present performance of IIA indicate that systematic work based on PIXE is now possible, despite the difficult Antarctic conditions.