Ladislav Strnad

Distinguishing regional and local sources of pollution by trace metals and magnetic particles in fluvial sediments of the Morava River, Czech Republic

PurposeRegional contamination of southern Moravia (SE part of the Czech Republic) by trace metals and magnetic particles during the twentieth century was quantified in fluvial sediments of the Morava River. The influence of local pollution sources on regional contamination of the river sediments and the effect of sampling site heterogeneity were studied in sediment profiles with different lithologies.Materials and methodsHundreds of sediment samples were obtained from regulated channel banks and naturally inundated floodplains and proxy elemental analyses were carried out by energy dispersive X-ray fluorescence spectroscopy (ED XRF) and further calibrated by inductively coupled plasma mass spectrometry (ICP MS). Magnetic susceptibility was determined as a proxy for industrial contamination. The age model for the floodplain sediments was established from 137Cs and 210Pb dating. Trace metal contamination was assessed by establishing the lithological background values from floodplain profiles and calculating enrichment factors (EF) of trace metals (i.e. Pb, Zn, Cu) and magnetic susceptibility for the entire study area.Results and discussionChannel sediments are unsuitable for the reconstruction of historical regional contamination due to their lithological heterogeneity and the “chaotic” influence of local sources of contamination, as well as the possibility of geochemical mobility of pollutants. On the other hand, sediments from regulated river banks qualitatively reflected the actual, local contamination of the river system.ConclusionsThis approach allowed us to distinguish the influence of local sources of contamination by comparison with more spatially averaged contamination signals from distal floodplain profiles. The studied area is weakly contaminated (EF ∼1–2), while individual sediment strata from regulated channel banks reflect local sources of contamination and contain up to several times higher concentrations of trace metals.

Regional Contamination of Moravia (South-Eastern Czech Republic): Temporal Shift of Pb and Zn Loading in Fluvial Sediments

Regional contamination by Pb and Zn in southern Moravia (south-east part of the Czech Republic) in the twentieth century was analysed in Brno Dam lake sediments and in floodplain sediments of the Morava River near Strážnice. The age model for the Brno Dam lake sediments has been obtained by 137Cs (maxima corresponding to the nuclear tests in atmosphere and the 1986 Chernobyl accident) and the construction of the dam (1940); the time constraints for the Morava River sediments was the erection of flood defences (1930s) and 210Pb dating. In the case of floodplain sediments, profiles exhibiting post-depositional mobilisation of heavy metals by pedogenic processes (gleying) must be excluded to reconstruct the history of contamination. There was a relatively fast joint onset of Pb and Zn load since the early stages of industrialisation in the first half of the twentieth century, but then the concentrations of these two metals developed in a different manner. Pb load only slightly increased till its peak in 1960s and 1970s. The increase of Zn load was rather stepwise: Soon before 1930s (Morava River floodplain) and in 1940s and 1950s (in Brno Lake), the relative contamination by Zn was much lower than during its peak in the 1970s to the present days. The offset of Pb and Zn contamination curves could have been caused by three different artificial sources of these heavy metals. The temporal shift of Pb and Zn loads can be used for dating sediments.

Alteration of arsenopyrite in soils under different vegetation covers.

The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental approach. Arsenopyrite in nylon experimental bags was placed in individual horizons in soils in spruce (litter, horizons A, B, and C), beech (litter, horizons A, B, and C) and unforested (horizons A, B, and C) areas and left in contact with the soil for a period of 1 year. The individual areas on the ridge of the Krusné hory Mts., Czech Republic, had the same lithology, climatic and environmental conditions. Scorodite (FeAsO(4).2H(2)O) was identified as a principal secondary mineral of arsenic (As) formed directly on the surface of the arsenopyrite. Scorodite was formed in all the areas in all soil horizons. The amount of scorodite formed decreased in the series beech, spruce and unforested areas. In forested areas, there was a larger amount of scorodite on arsenopyrites exposed in organic horizons (litter, A horizon). The greater rate of arsenopyrite alteration in organic horizons in the beech stand compared to spruce stand is probably a result of faster mineralization of organic material with resulting production of nitrate and better seepage conditions of soil in this area. Speciation of As determined using the sequential extraction technique demonstrated that As was bonded in the soils primarily in the residual fractions prior to the experiment. The As content in the mobile fractions increased in the organic horizon in the forested areas after the experiments.

Pollution assessment using local enrichment factors: the Berounka River (Czech Republic)

PurposeThe Berounka River is considered a relatively clean river, but recent studies have reported various levels of pollution. The purpose of this work is to identify anthropogenic pollution by metals (i.e. Pb, Zn, Cu) and magnetic particles in the sediments of that river and its tributaries.Materials and methodsSamples were obtained from hand-drilled cores taken from representative areas within the fluvial system; in distal floodplains (overbank fines) and closer to the channel (laterally deposited sediments). Samples were subjected to analysis using mass magnetic susceptibility (MS), X-ray fluorescence spectrometry (XRF) and also by inductively coupled plasma mass spectrometer (ICP MS) which allowed for a determination of 206Pb/207Pb isotope ratios. Macroelement ratios (K/Ti and Ti/Al) were used to distinguish variegated sediment provenance in the Berounka system. Normalization of trace elements by Ti (in the case of trace elements) and by Fe (magnetic susceptibility) allowed us to establish lithogenic background functions of trace elements and magnetic susceptibility within these two geologically different areas. A pollution assessment of the study area was performed using magnetic susceptibility and local enrichment factors (LEFs) for the risk elements. By comparing 1/(LEF Pb) and Pb isotopic composition, the origins of Pb within the catchment were determined. This unique method was able to distinguish Pb from various origins.Results and discussionThe upper parts of the floodplain cores contained higher levels of trace elements and magnetic particles (anthropogenically polluted), but samples taken from the cores in the active channel belt exhibited considerably higher concentrations of trace elements and magnetic particles than the upper parts of the floodplain cores and to much greater depths. We interpreted the deeper parts of the floodplain cores as a local lithogenic background. The upper parts of floodplain sediments hence showed moderate pollution (LEF of Pb and Zn ∼2, MS ∼2.5); whereas laterally deposited sediments showed significantly higher LEF values (LEF of Pb ∼6, Zn ∼9, MS ∼8).ConclusionsThe analysis of the sediments confirmed that the Berounka River system contains higher concentrations of trace elements and magnetic particles than can be accounted for by natural geological processes. Our pollution assessment of the Berounka River and its tributaries demonstrated that their sediments are moderately polluted from sources situated on its tributaries: Ag–Pb mining near the city of Stříbro in the Mže catchment; Pb–Zn mining in the Příbram ore district in the Litavka catchment and Fe ore processing and smelting in the Klabava catchment.

Dissolution kinetics of Pd and Pt from automobile catalysts by naturally occurring complexing agents

Powder samples prepared from gasoline (Pt, Pd, Rh, new GN/old GO) and diesel (Pt, new DN/old DO) catalysts and recycled catalyst NIST 2556 were tested using kinetic leaching experiments following 1, 12, 24, 48, 168, 360, 720 and 1440-h interactions with solutions of 20mM citric acid (CA), 20 mM Na(2)P(4)O(7) (NaPyr), 1 g L(-1) NaCl (NaCl), a fulvic acid solution (FA-DOC 50 mg L(-1)) and 20 mM CA at pH 3, 4, 5, 6, 7, 8 and 9. The mobilisation of platinum group elements (PGEs) was fastest in solutions of CA and NaPyr. In the other interactions (NaCl, FA), the release of PGEs was probably followed by immobilisation processes, and the interactions were not found to correspond to the simple release of PGEs into solution. Because of their low concentrations, the individual complexing agents did not have any effect on the speciation of Pd and Pt in the extracts; both metals are present in solution as the complexes Me(OH)(2), Me(OH)(+). Immobilisation can take place through the adsorption of the positively charged hydroxyl complexes or flocculation of fulvic acid, complexing the PGEs on the surface of the extracted catalysts. The calculated normalised bulk released NRi values are similar to the reaction rate highest in the solutions of CA and NaPyr.

Radiation damage in sulfides: Radioactive galena from burning heaps, after coal mining in the Lower Silesian basin (Czech Republic)

Abstract The isotopic composition of lead (207Pb/206Pb, 208Pb/206Pb, and 210Pb) in a recently formed galena from burning heaps after coal mining in Radvanice, Markoušovice, and Rybníček, the Lower Silesian basin, Czech Republic, was studied in detail. 210Pb activity in galena varied from 135 ± 9 to 714 ± 22 Bq/g and calculated integral doses ranged from 2.21 × 1011 to 6.11 × 1011 α/g. The radioactivity of the galena causes micro-deformations in its crystal structure as indicated by the Williamson-Hall graphs, showing that the level of micro-strain depends on the length of time that galena samples were exposed to the radiation. However, the crystal structure of galena is affected very inhomogenously; according to TEM investigations there are domains of fully crystalline, polycrystalline, and fully metamict galena within one crystal. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the isotopic composition of the studied galena. The stable isotope ratios of Pb varied for 207Pb/206Pb from 0.8402 to 0.8435 and for 208Pb/206Pb from 2.0663 to 2.0836. The average ratios 207Pb/206Pb = 0.8312 and 208Pb/206Pb = 2.0421 were obtained for coal from the same localities. These isotope ratios show that there is no isotopic fractionation taking place during the coal burning and subsequent galena crystallization from hot gases.

The pH-dependent release of platinum group elements (PGEs) from gasoline and diesel fuel catalysts: Implication for weathering in soils.

Powdered samples of new and old gasoline catalysts (Pt, Pd, Rh) and new and old diesel (Pt) catalysts were subjected to a pH-static leaching procedure (pH 2-9) coupled with thermodynamic modeling using PHREEQC-3 to verify the release and mobility of PGEs (platinum group elements). PGEs were released under acidic conditions, mostly exhibiting L-shaped leaching patterns: diesel old: 5.47, 0.005, 0.02; diesel new: 68.5, 0.23, 0.11; gasoline old: 0.1, 11.8, 4.79; gasoline new 2.6, 25.2, 35.9 in mg kg(-1) for Pt, Pd and Rh, respectively. Only the new diesel catalyst had a strikingly different leaching pattern with elevated concentrations at pH 4, probably influenced by the dissolution of the catalyst carrier and washcoat. The pH-static experiment coupled with thermodynamic modeling was found to be an effective instrument for understanding the leaching behavior of PGEs under various environmental conditions, and indicated that charged Pt and Rh species may be adsorbed on the negatively charged surface of kaolinite or Mn oxides in the soil system, whereas uncharged Pd and Rh species may remain mobile in soil solutions.

Speciation analysis of elements accumulated in Cystoderma carcharias from clean and smelter-polluted sites

Collections of Cystoderma carcharias sporocarps were sampled from clean and smelter-polluted sites and analyzed for Ag, As, Cd, Cu, Pb, Se, and Zn contents. Concentrations of all elements were significantly higher in samples from the smelter-polluted area. Except for As and Pb, all elements were effectively accumulated in the sporocarps at both clean and polluted sites. With the highest concentration of 604 mg Cd kg-1, C. carcharias can be considered as Cd hyperaccumulator. As revealed by HPLC-ICPQQQMS analysis, the As species in sporocarps from clean and polluted areas involved besides the major arsenobetaine a variety of known and unknown arsenicals; the occurrence of dimethylarsinoylacetate and trimethylarsoniopropionate is reported for the first time for gilled fungi (Agaricales). Size-exclusion chromatography of C. carcharias extracts supported by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and RP-HPLC data indicated that detoxification of intracellular Cd and Cu may largely rely on metallothioneins (MT) or MT-like peptides, not phytochelatins.