GACR

The Přídolí Series remains unique in the Phanerozoic as it is the only series recognized by the IUGS that has not been formally divided into stages. This state is being criticized for a long timeas it causes serious difficulties in global correlation of the upper Silurian. The GSSP of the Přídolí Series is in the Prague Synform, where it consists of carbonate facies rich in conodonts accompanied by moderately common graptolites. Therefore the main focus on possible subdivision of the Přídolí is based on integration of graptolite and refined conodont biozonation. The interpretation and timing of paleoenvironmental changes and bioevents across the Přídolí will be based on studies of six selected sections in the stratotype area and will include: 1. biotic data (changes in plankto-nekto-benthic faunas), 2. geochemical data (trace elements geochemistry and δ18O and δ13C isotope analyses), and 3. chemo–physical data (MS and GRS logs). A generalized correlation chart for the Přídolí Series in the Prague Synform with all available data will be a basis for prospective global subdivision. The aim of the project is integration of data on marine faunas and geochemical data from sections of the Prague Synform into a generalized correlation chart for the Přídolí Series in the stratotype area as a key document for the prospective chronostratigraphic subdivision of the Series.

The project combines geochemical, mycological, and molecular biology approaches and aims to provide better understanding of the factors and mechanisms affecting accumulation of Ag, Cu, Cd and Cd in macrofungi. To assess environmental factors in situ, the fractionation and mobility of metals in soil horizons will be analyzed at model sites. Colonization of soil horizons will be studied in Amanita strobiliformis. Pb isotopic composition of sporocarps will be used to trace the soil depth origin of accumulated metals. Distinct mycelial isolates of A. strobiliformis and Hebeloma mesophaeum will be subjected to phenotypic characterization, and subcellular metal species and expression of metal-related genes in mycelia will be investigated; gene-silencing and heterologous gene expression will be used to prove gene function or redirect the flow of intracellular metals. The accumulation of target metals and their intracellular forms will further be investigated in sporocarps of representative taxa, with special emphasis on Russula, Cystoderma a Phaeocollybia spp.

Weathering of sandstone is a widely studied topic by scientists from a number of geological, geomorphological and stone conservation disciplines. This research project is focused on a detailed study of the effect of gravity induced stress on the weathering of natural and artificial sandstone monuments. The fundamental concept – negative feedback between stress and erosion – has been published by us in 2014 in Nature Geoscience journal. A number of issues from this paper, however remain to be resolved. In this research project, elaborate 3D physical and numerical models of both sandstone landforms and man-made monuments (such as the monuments of the ancient town of Petra, Jordan) will be set up. A physically-based model for sandstone degradation will be developed, implemented in the finite element code and used in analyses of various natural and man-made sandstone forms. The effect of load on the erosion rate will be studied experimentally on various natural cemented sandstones. The effect of stress will also be studied on the evolution of open fracture porosity in sandstone aquifers.

The aim of the project is to assemble composite record of the evolution of continental environment in central Europe in period around the onset of Miocene Climatic Optimum from lacustrine sediments of the Most Basin in the Ohre (Eger) Rift. Drill cores 70-380 m long will be analysed from both central and marginal parts of the basin to limit specific influences of local source areas and tectonics. The work will be based on the use of magneto-, chemo- and cyclostratigraphy. Chemo- and cyclostratigraphy will be based on variation of sediment composition reflecting paleoenvironment in the lake watershed as well as lake hydrology; efficiency of proposed tools has already been successfully tested. The project will produce new record of the onset of the Miocene Climatic Optimum and allow its comparison with existing records, e.g. from the Paratethys area. It will contribute to understanding of the environmental changes with unprecedented temporal resolution of 1-2 thousand years.

Fish fauna of the Paratethys region has been described from different parts of Europe and western Asia. Moravia (Czech Republic; Central Paratethys) yielded rich material and ranks among the key areas. Four promising sites from two stratigraphic levels were selected for study within the proposed project. New data will allow to analyze and interpret relationships among fish assemblages from Oligocene to Lower Miocene. Principal aims of this project are: 1) description of fish assemblages at both stratigraphic levels on the basis of studied specimens, relationships among these assemblages, the nature of changes, and factors that could have induced such changes (especially paleoecological); 2) a detailed description of morphological changes within selected taxonomic groups in the studied time interval and explanation of their possible causes; 3) improvement of taxonomic interpretation of selected fossil fish groups on the basis of the studied specimens. The obtained results may outline general behavior of fish assemblages under specific conditions over time.

Forest ecosystems of the Czech Republic were exposed to a high level of pollutant deposition originating from coal burning in the 20th century. But studies investigating the fate of contaminants, such as toxic mercury, in the environment have been rather scarce. This project aims to explore the fate of mercury in forest ecosystems and its transformation to the highly toxic methylmercury in soils of two contrasting sites at the pristine Bohemian Forest and relatively polluted Beskids Mountains. We will fill a gap in the knowledge of historical deposition in northeastern Moravia through analysis of peat cores. Because the level of mercury deposition is an important parameter affecting the methylation processes, we will evaluate current mercury deposition at both sites and compare it to a reference site. Finally, forests at both contrasting study areas were subject to forest decline in the past decade due to insect infestations. Thus another aspect of this study will be to assessthe effect of forest dieback on methylation processes in polluted and unpolluted regions.

The aim is to contribute the global definition of the Jurassic-Cretaceous boundary integrating magnetostratigraphy, biostratigraphy, geochemistry and sedimentology data. Supplementary data and their evaluation enable to obtain accurate high-resolution stratigraphic schemes with high potential for multi-proxy correlation of selected regions, and sooner or elsewhere studied areas with marine sequences. The data will serve for the creation of database of integrated stratigraphy. Key sections of the research are Isle of Purbeck (England), Le Chouet and St Bertrand's Spring (France), Kurovice and Štramberk (Czech Republic). The correlation of sub-Boreal (Purbeck) and Tethyan regions (sections at Bosso - Italy, Puerto Escano - Spain, Brodno – Slovakia, Barlya – Bulgaria, Fedosiya – Crimea, Mezatepec - Mexico) is of special importance. The research will be carried out in the cooperation with the International Subcommission on Cretaceous Stratigraphy and thus contributing the definition of the boundary, which remains the last boundary of geological formations without global stratotype.

Acoustic emission (AE) is the process accompanying the brittle fracturing of solid body and simultaneously an indispensable tool for its study. Laboratory experiments under controlled loading conditions make it possible to differentiate the effect of important factors like material structure, stress field, crack presence, etc. on fracture initiation and development, and allow simulate the nature in situ. We will detect and classify the shear and tensile modes of rock fracturing by inverting the AE data gathered using a multichannel AE event recording system. The goal is to reveal mutual influence of rock structure and stress orientation, as well as the impact of microcrack concentration and orientation on the fracture mode changes. A novel source model consisting straight from the individual fracture modes will be applied for inversion of AE data, which is more robust in contrast to the traditional moment tensor against common deficiencies in the setup of the inverse task, like noise in the data, mislocation, inexact velocity model and sparse configuration of the sensors.

Ecosystems of the Planet Earth are contaminated by toxic elements, major part of which is usually of anthropogenic origin. Although natural cycle of mercury (Hg) was not affected as much by anthropogenic activities as i.e. cycle of lead, its effects on human health and health condition of ecosystems is incomparable. The environment of the Czech Republic is bearing several loads, which originate in its past industrial processing, similarly to selected areas in Poland or Germany. A complex study of the mercury behavior in forest ecosystems of the Czech Republic is thus needed. The data on accumulation or export of mercury from the ecosystems are also unsatisfactory. Existing data on the mercury content in top horizons of forest soils indicate significant contamination, namely in the central Czech Republic. This biogeochemical study aims to evaluate the mercury concentrations and pools in the compartments of the forest ecosystem.

According to present knowledge, the actually used provisional Boreal and the Tethyan J/K boundaries are heterochronous. All attempts to correlate the boundary J/K beds between the Boreal and the Tethyan realms by biostratigraphic methods failed. The aim of the project is to make a detailed and precise correlation of the J/K boundary interval in the Tethyan and Boreal region on the paleomagnetic (localization of reversed subzones) and geochemical base (included the isotope geochemistry and neutron activated analyses). On several pilot localities in the Tethyan region (e.g. Bosso-Italy, Brodno-Slovakia, Puerto Escaňo-Spain) was already successfully used for correlation the high resolution magnetostratigraphy together with detailed microbiozonation.On the only known J/K boundary section without hiatuses in the Boreal realm - Nordvik peninsula in Russia - was successfully elaborated by high resolution magnetostratigraphy together with ammonite biostratigraphy. The project use the methods of high