CHARACTERIZATION OF PARTICULATE MATTER FROM THE KARA SEA USING ELECTRON-PROBE X-RAY MICRO-ANALYSIS

Automated electron probe X-ray micro-analysis (EPXMA) was used to char acterise 17600 individual particles collected in the Kara Sea and in t he estuary of the Yenisey River. Samples were obtained by filtering an d centrifugation of particles in suspension and from bottom sediments. Multivariate techniques were used to reduce the enormous data sets. B y testing hierarchical, non-hierarchical and fuzzy clustering on the c entrifuged suspension samples, it was shown that hierarchical clusteri ng is most suitable. The two other clustering techniques are very time consuming and in most cases do not add any additional information. Th is hierarchical clustering of the data matrix results in different par ticle types which can be apportioned to their possible sources. The al uminosilicate particle types dominate in all samples and suppress the relative abundances of other interesting groups like metal-rich partic les. However, Fe-rich and Ti-rich particles are still frequently found . Since the nearest industry is 200 km from the sampling site, it is e specially surprising to find high contributions for Ti-rich particles which, because of their small diameter (i.e. between 0.6 mu m and 1.1 mu m), are most likely of anthropogenic origin. To complete this study the homogeneity and morphology of 100 particles from water suspension samples were analysed using manual EPXMA.