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Mercury concentrations in the air and in forest crops

The January issue of Vesmír, the Czech popular science journal celebrating its 150 anniversary in 2021, published two papers authored by members of the Department of Environmental Geology and Geochemistry of the Institute of Geology. The first paper by Borovička, Roll and Nováková deals with the safety of collecting edible mushrooms and forest fruits at sites affected by historical mining of mercury-rich ores. The second paper by Navrátil and Rohovec brings news about the possibilities of using passive samplers to monitor mercury concentrations in the air.

Carboniferous eruption covered central and western Bohemia with up to 1 m thick ash layer

The famous Bělka tuff is an areally extensive pyroclastic layer preserved in the central and western Carboniferous late- to post-orogenic basins of central and western Bohemia. This tuff represents a unique stratigraphic marker documented from tens of boreholes and numerous black coal mines within a large area between the southern edge of the Pilsen Basin in western Bohemia and the eastern part of the Kladno-Rakovník Basin over a distance of 100 km. However, its volcanic source has been as yet enigmatic. In a new study by Tomek et al., published in International Geology Review, a multidisciplinary approach using the LA-ICP-MS U/Pb zircon dating, analysis of thickness and grain size distribution, and volume calculation suggested that the source volcano was the Altenberg–Teplice Caldera located at the Czech–German border in NW Bohemian Massif. In detail, this volcano underwent a major caldera-forming ignimbrite eruption with an estimated volcanic explosivity index 7 (out of 8) at 314 Ma. From the northern caldera margin, pyroclastic density currents travelled south over a distance of ca. 40 km towards the area of Oparno valley (Porta Bohemica). From here, northeasterly winds distributed the volcanic ash cloud towards the southwest, where the ash was deposited in the sedimentary basins. As indicated by an isopach reconstruction, the Regensburg area (Germany), for instance, was covered by a 10 cm thick ash layer that originated from the Altenberg–Teplice Caldera nearly 220 km away. For additional information click here.

Lampyrite

The Journal of Petrology, published by Oxford University, has recently published an extensive study by Czech and German researchers summarizing the results of their study of late-Variscan mantle-derived magmatic activity in the Bohemian Massif. Based on a combined research of radiogenic and non-radiogenic isotopes, the development of the composition of the upper mantle beneath the Bohemian Massif was reconstructed for a time span of 65 million years. The study was coordinated by Lukáš Krmíček of the Institute of Geology of the Czech Academy of Sciences and provides a recognition of a specific rock type described under a new term – lampyrite.

Lithium

“Without taking notice, we got accustomed to the use of light laptops, thin mobile phones, and small electronics. We are no longer surprised by the possibility of recharging and discharging the battery repeatedly, and we take it for granted that the energy stored in this ‘can’ is easily available. The word lithium has penetrated the dictionary of the general public.” This is an introduction to a new popular-science article by our colleagues Jan Rohovec and Tomáš Navrátil, recently published in the Vesmír magazine, where you can find more details.

Ancient sea-level fluctuations due to vast glaciations

Black shales provide important clues to paleoenvironmental changes of the Earthʼs oceans and atmosphere throughout the geological history. In the Bohemian Massif, black shales were commonly deposited at, or very close to, the Neoproterozoic/Cambrian boundary, also known as the period of “Life Explosion”. The new study led by Lukáš Ackerman of the Institute of Geology and published in the Marine and Petroleum Geology journal (link here) focused on two black shale successions. It revealed that their deposition was intimately connected with the waning activity of a volcanic arc, changes in anoxic-oxic conditions and a global sea level change in response to large-scale periods of glaciation between 580 and ~550 Ma.

Is arsenic responsible for the toxicity of the Violet Crown Cup?

The Violet Crown Cup, Sarcosphaera coronaria, is a nicely coloured spring mushroom. In earlier days, the mushroom was considered edible, but several poisonings were reported in the early 20th century. The reason for the sporadic toxicity of S. coronaria is still unknown. The presence of arsenic could be a possible explanation, since Crown Cups can take up high amounts of this toxic element. Arsenic concentration and speciation were investigated in S. coronaria with inductively coupled plasma mass spectrometry (ICPMS) and HPLC coupled to ICPMS and revealed incredible maximum values of 0.9 % As (dry mass). Most of it was present in the form of methylarsonic acid (MA), a less toxic form of this element. However, low concentrations of the highly toxic methylarsonous acid (MA [III]) were also detected. The amounts were too low to pose an acute risk for consumers but the concentration of MA (III) significantly increased during simulated gastric digestion. We could not unambiguously identify arsenic as the toxic constituent of S. coronaria but we demonstrated that the extremely toxic MA (III) can be formed under certain circumstances, which should be carefully investigated in the future. This international research was conducted in co-operation of two Czech Academy of Sciences institutes (Institute of Geology, Nuclear Physics Institute) and the Austrian University of Graz.

An award for Václav Cílek

We have the pleasure to announce that Václav Cílek, our colleague and the former Director of the Institute of Geology, was awarded the Prize of the Chairman of the Research, Development and Innovation Council (R&D&I Council). This award, granted for outstanding activities in popular science promotion, was presented – on behalf of the Chairman – by Karel Havlíček, the Deputy Prime Minister, the Vice-Chairman of the R&D&I Council, the Minister of Industry and the Minister of Transport. This event was held within a festive, though modest, ceremony in the Hrzán Palace on October 13, 2020, at the presence of the President of the Czech Academy of Sciences Eva Zažímalová. Many congratulations, Václav! For details on the award, click here.

A contribution to the geologic history of bark beetles

Insect borings, unique in the fossil record, were found in fossil wood from a thin lignite seam of lowermost Cretaceous age, exposed in cliffs of the southwestern shore of the Isle of Bornholm (Denmark). The find consists of six thin, roughly parallel, short passages connected with a remnant of a long straight tunnel running along a mechanically-induced fissure just below the wood surface. This find is not fully analogous with the presently most common feeding insect borings as the passages are situated in an oblique fissure of the wood sample (instead of the usual position below the bark). Nevertheless, the best modern analogues of the borings found in Bornholm still come from the insect forestry pests such as the Scolytidae (bark beetles). The find shows that ecological predecessors of bark beetles probably first inhabited random mechanic cracks; later, they occupied the most devastating niche at the boundary between the bark and the wood. More in the paper (Journal Ichnos).

Fossil fishes from northern Bohemia targetted by scientists again

Modern gobies (Gobioidei, Teleostei) are classified to eight families, although exclusively fossil representatives of this suborder have been reported too. One of these extinct forms is the small fish of the genus Pirskenius, which was originally placed into a specific family Pirskeniidae, or to the family Eleotridae (sleeper gobies). Its specimens are known only from Oligocene deposits of northern Bohemia. New research published in journal Plos One, also contributed by T. Přikryl of the Institute of Geology, focused on this Oligocene genus and compared it with other gobiids using modern methods including micro-CT scanning. Detailed analyses validated the separate family Pirskeniidae and resulted in more precise diagnoses for the genus Pirskenius and the family Pirskeniidae. The results of phylogenetic analysis suggest that the family Pirskeniidae represents a sister group of the clad Thalasseleotridae + Gobiidae + Oxudercidae. In a broader context, the intrusion of gobiids into the Oligocene freshwater environment can be viewed as an impus generating new forms which became extinct shortly after their spread.

Geology of the Bohemian-Saxonian Switzerland embedded in a book

Long-lasting work of a team of authors dealing with the territory of Bohemian-Saxonian Switzerland was completed in spring this year. It materialized into a book under the editorship of RNDr. Zuzana Vařilová, PhD. of the Municipal Museum of Ústí nad Labem. With its 576 pages, the book represents the most extensive publication ever written on the geology of this region. Scientists of the Institute of Geology of the Czech Academy of Sciences are the leading authors of chapters Geology, Tectonics and Geomorphology. Presentation of the book with the whole team of authors will take place at Ústí nad Labem on September 24.

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