Zdeněk Řanda

Bioaccumulation of silver in ectomycorrhizal and saprobic macrofungi from pristine and polluted areas

Macrofungi are effective accumulators of Ag. This study provides a comprehensive review of this phenomenon supported by original data on the Ag concentrations of macrofungi from pristine and Ag-polluted areas. In pristine areas, the median Ag concentrations of ectomycorrhizal (ECM) and saprobic (SAP) macrofungi were 0.79 and 2.94 mg kg(-1), respectively. In these areas, hyperaccumulation thresholds for Ag in ECM and SAP macrofungi are proposed as 100 and 300 mg kg(-1), respectively. In a Ag-polluted area, the Ag concentrations in macrofungi (ECM and SAP) were significantly elevated with the median value of 24.7 mg kg(-1) and the highest concentrations in Amanita spp. of the section Vaginatae (304-692 mg kg(-1)). The intracellular speciation of Ag in fruit-bodies of the Ag-accumulator Amanita submembranacea was inspected by size exclusion chromatography followed by sulfhydryl-specific fluorimetric assays of ligands using reverse phase high-performance liquid chromatography and improved polyacrylamide gel electrophoresis. Virtually all Ag was found to be intracellular and sequestered in the major 7 kDa and minor 3.3 kDa complexes. The lack of glutathione and phytochelatins and the presence of a single 3 kDa sulfhydryl-containing peptide in the isolated Ag-complexes suggest that detoxification of Ag in A. submembranacea may rely on metallothionein. Vertical distribution of Ag in a polluted forest soil profile has shown substantial enrichment in organic horizons; in polluted technosol, the highest Ag concentrations were found in surface layers. Standardized EDTA extraction of Ag in both the investigated soil profiles showed relatively low Ag extractibility, generally within the range of 2.2-7.7% of total Ag content.

Elemental characterization of the new Czech meteorite ‘Morávka’ by neutron and photon activation analysis

Forty two major, minor and some trace elements were determined by activation analysis in the new Czech Morávka H5 chondrite, which fell on May 6, 2000 in the vicinity of Morávka, north-east Moravia. The elements Na, Mg, Al, Si, Cl, Ca, Ti, V, Mn, Co, Ni, and Cu were determined by means of instrumental short-time neutron activation analysis (INAA), whereas another group of elements, namely Sc, Cr, Fe, Co, Ni, Zn, As, Se, Br, Sb, La, Sm, Ir, Au and Hg were assayed using long-time INAA. Most of the rare earth elements (REE) were determined by radiochemical neutron activation analysis (RNAA) using precipitation of their oxalates, whilst for the determination of Rb and Cs an RNAA procedure based on selective sorption of the elements on ammonium phosphomolybdenate was employed. Mg, Ca, Ti, Mn, Ni, Sr, Y and Zr were determined by instrumental photon neutron activation analysis (IPAA) using the irradiation with 20 MeV bremsstrahlung from a microtron. For quality control, the U.S. Geological Survey (USGS) reference rocks basalt BCR-1 and diabase W-1 were analyzed. Moreover, the self-verification principle in activation analysis was employed to increase the credibility of the obtained results.

Chemical composition of plant silica phytoliths

Silica phytoliths are a subgroup of biogenic opal. Silica phytoliths are formed in many plant species and remain preserved in soil and sediments after plant decay. The chemical composition of fossil phytoliths may reveal ancient plant taxa, soil composition and climate. However, actually detailed knowledge on silica phytolith composition is scarce. Here we present result of instrumental neutron activation analysis of barley awns, stems and leaves, and barley phytoliths. The elements of interest were Na, Mg, Al, Si, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Br, Rb, Sb, Cs, Ba, La, Ce, Sm, Eu, Tb, Dy, Yb, Hf, Ta, W, Th, and U. We compared three phytolith extraction methods: dry ashing, acid digestion, and acid digestion followed by incineration. We found that sole acid digestion is inefficient to remove organic matter. By contrast both dry ashing and acid digestion followed by incineration are suitable for phytolith analysis. Comparison of phytoliths with their source plant material shows that phytoliths are enriched in terrigenous elements such as Al, Sc, Ti, V, Cs, Fe, rare earth elements, and depleted in the major inorganic constituents of plants such as K, Ca, Mg, Mn, Cl and Br.

Geochemical evidence for the origin of moldavites

Abstract Forty-eight moldavites and samples of rocks from the impact crater of Ries were analyzed using non-destructive neutron activation analysis. The following elements have been determined: La, Ce, Sm, Eu, Lu, Sc, Co, Cs, Hf and Th; and Rb and Cr in two moldavites. The darker moldavites, more common in Moravia, show higher contents of trace elements than those lighter in colour, from Southern Bohemia. Terrestrial igneous rocks cannot be regarded as a suitable source material, but terrestrial sandy to silty claystones show strong similarities in major and trace element abundances, and exhibit analogous inter-element variations to moldavites. The Tertiary claystones and sandstones which probably covered the Ries area before the impact, are a possible source rocks for moldavites.

Geochemical characterization of impact glasses from the Zhamanshin crater by various modes of activation analysis. Remarks on genesis of irghizites

A large set of impact glasses from the Zhamanshin crater in Kazakhstan was analyzed by various modes of instrumental neutron activation analysis, supplemented by instrumental photon activation analysis and prompt gamma-ray activation analysis. Results of the determination of more than forty major and trace elements have shown that the analyzed set of homogeneous, tektite-like impact glasses with size of several centimeters and of various forms could be divided into two geochemically different groups. The lustrous, silica rich (acidic) glasses with high Ni content have been classified conventionally as irghizites. The dull, silica poor (basic) glasses with very low Ni content should not be confused with the large, heterogeneous impactite forms—zhamanshinites, but considered as a separate type of impact glass. Within both primary groups, further division has been suggested based on lower contents of Ni in an irghizite subgroup, and evidence of mixing of source materials for both primary groups in a part of the basic glasses. Based on the contents of Ni, Cr, Mn, Fe and Co, an ordinary chondrite impactor has been suggested with its contribution to the irghizite matter ranging between 4 and 21%. Possible source materials and impact processes leading to irghizite formation have been outlined.

Rare earth elements in tektites

Abstract Four moldavites and one sample each of an australite, billitonite, indochinite, philippinite, thailandite, Ivory Coast tektite, bediasite and a georgianite were analyzed using neutron activation analysis for La, Ce, Sm, Eu, Tb, Yb and Lu. The REE abundances resemble those of sedimentary rocks. Most of the tektites display a depletion of Eu, a characteristic feature of mature Phanerozoic continental sedimentary rocks. However, the Ivory Coast tektite and georgianite are relatively enriched in Eu, possibly due to the presence of plagioclase-rich source rocks.

On the possible role of macrofungi in the biogeochemical fate of uranium in polluted forest soils.

Interactions of macrofungi with U, Th, Pb and Ag were investigated in the former ore mining district of Příbram, Czech Republic. Samples of saprotrophic (34 samples, 24 species) and ectomycorrhizal (38 samples, 26 species) macrofungi were collected from a U-polluted Norway spruce plantation and tailings and analyzed for metal content. In contrast to Ag, which was highly accumulated in fruit-bodies, concentrations of U generally did not exceed 3mg/kg which indicates a very low uptake rate and efficient exclusion of U from macrofungi. In ectomycorrhizal tips (mostly determined to species level by DNA sequencing), U contents were practically identical with those of the non-mycorrhizal fine spruce roots. These findings suggest a very limited role of macrofungi in uptake and biotransformation of U in polluted forest soils. Furthermore, accumulation of U, Th, Pb and Ag in macrofungal fruit-bodies apparently does not depend on total content and chemical fractionation of these metals in soils (tested by the BCR sequential extraction in this study).

Possibilities of simultaneous determination of lead and thallium in environmental and biological samples by microtron photon activation analysis with radiochemical separation

A method for simultaneous determination of lead and thallium by photon activation analysis with radiochemical separation using irradiation with bremsstrahlung produced by a 20 MeV microtron is described. The detection limits for 500-mg samples of 0.9 μg·g-1 and 0.15 μg·g-1 for lead and thallium, respectively, were achieved that are sufficiently low for the reliable determination of both elements at levels commonly occurring in environmental samples and at elevated levels in biological materials. The accuracy of the procedure developed was proved by analyses of a number of environmental and biological reference materials. Possibilities of detection limit improvements are also discussed.

Tertiary alkaline Roztoky Intrusive Complex, České středohoří Mts., Czech Republic: petrogenetic characteristics

The České středohoří Mts. is the dominant volcanic center of the Ohře (Eger) rift zone. It hosts the Roztoky Intrusive Complex (RIC), which is made up of a caldera vent and intrusions of 33–28-Ma-old hypabyssal bodies of essexite–monzodiorite–sodalite syenite series accompanied by a radially oriented 30–25-Ma-old dike swarm comprising about 1,000 dikes. The hypabyssal rocks are mildly alkaline mostly foid-bearing types of mafic to intermediate compositions. The dike swarm consists of chemically mildly alkaline and rare strongly alkaline rocks (tinguaites). The geochemical signatures of the mildly alkaline hypabyssal and associated dike rocks of the RIC are consistent with HIMU mantle sources and contributions from lithospheric mantle. The compositional variations of essexite and monzodiorite can be best explained by fractional crystallization of parent magma without significant contributions of crustal material. On the other hand, the composition of monzosyenite, leuco-monzodiorite and sodalite syenite reflects fractional crystallization coupled with variable degrees of crustal assimilation. It is suggested that the parent magmas in the Ohře rift were produced by an adiabatic decompression melting of ambient upper mantle in response to lithospheric extension associated with the Alpine Orogeny.

Determination of impurities in natural diamonds using neutron activation and high-resolution gamma-spectrometry

Thirty-five natural diamonds from six widely differing localities, weighing from 3.6 mg to 305.3 mg were subjected to instrumental neutron activation analysis using high-resolution semiconductor gamma-spectrometry. By means of short-term and long-term activation in a nuclear reactor, Na, Sc, Cr, Mn, Co, La, Ce, Sm, Eu, Hf, Au, Hg, and Th were determined in all the samples, K, Sr, Ag, Cs, Ba, Yb, Lu and W in some, and qualitative determination was carried out with Ca, Fe, Ni, Ga, As, Zr, Sb, Tb, Dy, Ta, It and U. The study serves as a basis for the study of the relationship between the colour, morphology and luminescence of diamonds and their impurity contents.