| Electron probe X-ray micro analysis (EPXMA) and scanning transmission electron microscopy-selected area electron diffraction combined with energy dispersive X-ray detection (STEM-EDX-SAED) have been used to characterize individual suspended particles collected in the Southern Bight of the North Sea, Lake Baikal, the Kara Sea and in rainwater from above the North Sea. All samples were dominated by mineral and biogenic particles and aluminosilicate, Si-rich and Ca-rich particles in particular. In the suspension collected from the rainwater also large abundances of organic particles have been detected. The organic content of the particles was studied by staining some samples with ruthenium tetroxide. This staining has proven that in natural waters all suspended particles have a coating of organic material, but it also indicated that the concentration of organic particles is small in the Southern Bight of the North Sea and that without staining most organic, but also aluminosilicate and trace metal rich particles, were overlooked and thus not included in the analyses. The analyses also showed the presence of small concentrations of anthropogenic particles, mostly trace metal rich particles but also Ti-rich particles, in the majority of the samples. The anthropogenic nature of these Ti-rich particles was proven using STEM-EDX-SAED. |
