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Rynek tantalu na początku XXI wieku

Krzak Mariusz, Gałaś Andrzej, Król Katarzyna

Przegląd Geologiczny

2021

Vol. 69, nr 4

234--243

Tantalum, despite the low consumption level, is one of the strategically important metals for the world economy. In terms of the world production volume, it places oneself on a distant position; however, its price was one of the highest at the beginning of the 21st century. Tantalum is a transition metal with a high melting point and high chemical resistance, which determines the spectrum of its applications. It is used mainly in the capacitors production, sputtering and as an additive for superalloys. The 21stcentury is a period of noticeable changes in the structure of quantitative supplies, consumption centres and price fluctuation. There are numerous but small centres of primary production (artisanal mines) in Africa. Sources of tantalum raw-materials (mineral deposits and its reserves), basic factors determining the economic situation on the market, substitution possibilities and the prices evolution are presented and assessed in the paper. Marginal significance of the economy of tantalum raw materials for Poland is mentioned.

Abundance and production of bacteria in a marine beach (Southern Baltic Sea)

Podgórska B., Mudryk Z., Skórczewski P.

Polish Journal of Ecology

2008

Vol. 56, nr 3

405-414

The paper presents the results of the study of abundance, biomass, mean cell volume and secondary production of bacteria inhabiting a marine-bay sandy beach, at southern Baltic Sea coast (Sopot) in summer season. The differences of bacteriological parameters among sites across beach horizontal profile were determined. Maximal value of the total bacteria numbers (8.59 [plus or minus] 0.73 x 10[^7]cells g[^-1] dw), biomass (15.2 [plus or minus] 4.4 [my]g C g[^-1] dw) and cell volume of bacterium (0.056 [plus or minus] 0.011 [my]m3) was noted at the waterline and bacterial secondary production was highest in the dune (172.3 [plus or minus] 86.6 [my]g C g[^-1] dw d[^-1]) and at the waterline (119.9 [plus or minus] 40.5 [my]g C g[^-1] dw d[^-1]). Marked differences in the level of bacteriological parameters between surface and subsurface sand layers were estimated. In the sea, at the waterline and in the middle of the beach higher numbers of bacteria, their biomass and secondary production were found in the surface (0.1 cm) than in the subsurface (5.10 cm) sand layers. A reverse situation was observed in the dune.