Accelerator mass spectrometry analysis of non-soluble carbon in aerosol particles from high alpine snow (Mt. Sonnblich, Austria)

With an elaborate accelerator mass spectrometry (AMS) technique radiocarbon measurements have been performed with aerosol carbon filtered from high al pine snow samples gathered consecutively at the high-altitude research stat ion Sonnblick (3106 m, Eastern Alps, Austria) during a snow storm in April 1997. The concentration of the water-insoluble carbonaceous material in the molten snow was on the average 310 mug Cn and the total sample amounts for analysis were in the range of 35 mug to 60 mug C. Using a special backgrou nd correction procedure tested on similar amounts of an urban particulate s tandard sample the accuracy of the corrected and normalized C-14/C-12 isoto pic ratios of the snow aerosol samples was in the order of 4% to 14% of the measured ratios. The water-insoluble carbonaceous material of five samples from Mt. Sonnblick exhibited a weighted mean of 74 pMC (percent Modern Car bon) with a range of 64 pMC to 88 pMC. Thus, it appears that about 64% of n on-soluble carbon in high alpine snow from Sonnblick was of biogenic origin . The temporal variations of the C-14/C-12 isotopic ratios of the snow aero sol samples were statistically significant, suggesting alterations in the c ontribution of specific aerosol sources.