Composition of individual aerosol particles above Lake Baikal, Siberia

More than 20,000 individual aerosol particles, taken from research vessels over the total area of Lake Baikal (Siberia) during June 1992 and September 1993, were analysed by automated electron probe X-ray microanalysis. The obtained data set was reduced by a combination of multivariate techniques. Hierarchical cluster analysis indicated 11 major particle types, among which soil dust, Fe-rich, Ca-rich, organic, biogenic, S-rich particles and gypsum were the most abundant. Abundance variations as a function of sampling position were investigated by means of nonhierarchical clustering techniques. Significant differences were found between the pristine northern and middle basin, and the anthropogenically influenced southern basin. Emissions from industrial complexes near Irkutsk and in the valley of the Angara and Selenga river seem to have an impact on the atmosphere over the lake. Samples taken in the proximity of the Baikalsk paper plant revealed a huge influence by the Factory on the natural aerosol. Principal factor analysis showed four possible sources of the Baikal aerosol.