Ge/Si ratios in marine siliceous microfossils

A procedure is presented to separate diatoms and radiolaria from marine sediments and from each other, to purify them of elements associated with other phases, and to dissolve them to determine their elemental composition. The cleaning procedure eliminates artifacts due to the presence of detrital clays and the high sorption capacity of hydrated silica. The concentration of trace elements (Al, Fe, Mg, and Ba) that we find in alkaline dissolutions of clean diatoms are at least an order of magnitude lower than previously reported. The overall long-term precision in the determination of Ge/Si in a sub-standard of clean diatoms is ±0.024 * 10**-6 (1 sigma). Ge/Si measured in diatoms and radiolaria from core tops indicates that high-latitude Holocene diatoms accurately record the present-day oceanic Ge/Si, while radiolarian ratios are systematically lower and display more scatter. Evaluation of Ge/Si in diatoms and radiolaria from Hole DSDP 265 (Plio-Pleistocene) suggests that post-depositional alteration of the ratio does not occur at this site, but the average ratio carried by diatoms over this time interval was lower than that in the present ocean.

Composition of airborne material from yellow snow fallen in the Russian North

Large amounts of dust responsible for bright colors of atmospheric precipitation in the temperate, subpolar and polar zones of the northern hemisphere have been rarely observed. In the twentieth century and in the beginning of the twenty first century in the Northern European Russia such events were not registered up to March 25-26, 2008. At that time in some parts of the Arkhangel'sk region, Komi Republic, and Nenets Autonomous Area atmospheric precipitation as sleet and rain responsible for sand- and saffron colors of ice crust formation on the snow surface was observed. During detailed mineralogical, geochemical, pollen, diatom and meteorological investigations it was established that semidesert and steppe regions of the Northwest Kazakhstan, Volgograd and Astrakhan' regions, and Kalmykia are the main sources of the yellow dust.