Martin Novák

Czech Geological Survey, Praha, Praha, Czech Republic

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Publications (64)145.31 Total impact

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    ABSTRACT: Measurements of nitrogen isotope ratios (δ15N) along vertical porewater profiles are instrumental in localizing sources and sinks of nitrous oxide (N2O) in wetland ecosystems. We present the first N2O concentration and isotope data for porewaters of ombrotrophic, mountain-top bogs. Our two study sites, situated in the Czech Republic at elevations higher than 1000 m, have been affected by atmospheric N pollution for more than 100 years. In recent decades, the northeastern site KB received over 30 kg N ha-1 yr-1 via atmospheric deposition, the southwestern site BS was 3 times less polluted. Both peat bogs were surrounded by defoliated, dead spruce stands. We hypothesized that elevated nitrate (NO3-) inputs in rain-fed bogs may cause sizeable N2O emissions. Porewater N2O concentrations in the studied ombrotrophic bogs were 400 to 800 times higher, compared to fens in nearby Bavaria (Germany). The highest N2O concentrations and the lowest δ15N-N2O values were found at the bottom of the sampled porewater profiles, 40 to 60 cm below surface. Low δ15N-N2O values resulted from a N isotope fractionation associated with denitrification. The site with the lower historical N pollution, BS, exhibited up to 7 times higher porewater N2O concentrations than KB, possibly due to a higher denitrification potential determined as abundance of nirK and nirS genes. Upcore, N2O abundance decreased and δ15N-N2O increased, indicating N2O reduction. Processes of N2O formation and consumption at different depths were integrated by measuring N2O fluxes across the peat – atmosphere interface. These fluxes were minute (< 0.02 µmol N2O m-2 h-1). We even observed scavenging of air-borne N2O by the bog substrate. Nitrogen pollution of ombrotrophic bogs led to vigorous N cycling, manifested by extremely high peat porewater N2O concentrations. However, effective in-situ consumption of the produced N2O greatly reduced its warming potential.
    Soil Biology and Biochemistry 11/2014; in press. · 4.41 Impact Factor
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    ABSTRACT: There are fears that global warming will lead to degradation of peatlands, higher emissions of greenhouse gases from peat, and accelerated warming. Anaerobic decomposition of organic soils produces methane (CH4), a potent greenhouse gas. Two peat bogs differing in mean annual temperature, Velke Darko (VD, Czech Republic, 7.2 °C), and Stor Åmyran (SA, Sweden, 4.0 °C), were selected for a comparative study of how organic soils in different climatic zones will respond to warmer and drier conditions. Twenty peat cores from each bog were incubated in growth chambers. Under present-day summer conditions, VD produced 14 times more CH4 than SA. Two different warming scenarios were used. Peat-core replicates were kept at temperatures of 11 versus 16 °C, and 11 versus 22 °C. From 11 to 16 °C, the CH4 production slightly decreased at SA, and slightly increased at VD. From 11 to 22 °C, the CH4 production increased 9 times at SA, but slightly decreased at VD. After an 8-month incubation, peat cores under drying conditions (water table at −14 cm) were compared to samples with original water table (−2 cm). Drying conditions led to a steeper reduction in CH4 production at VD, compared to SA. The CH4 production decreased more than 100 times at VD. Then, the combined effect of simultaneous warming and drying at 11 and 22 °C was studied. We did not find any significant effect of interactions between increasing temperature and decreasing water table level. Overall, the warmer site VD responded more strongly to the simulated climate change than the colder site SA.
    Mitigation and Adaptation Strategies for Global Change 10/2014; · 1.86 Impact Factor
  • Biogeomon 2014, 8th International Symposium on Ecosystem Behavior, University of Bayreuth, Bayreuth, Germany; 07/2014
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    ABSTRACT: Carcinogenic effects of hexavalent chromium in waters are of concern in many countries worldwide. We explored Cr isotope systematics at 11 sites in the Czech Republic and Poland. Geogenic Cr pollution was associated with serpentinite bodies at former convergent plate margins, while anthropogenic Cr pollution resulted from electroplating, tanning, and chemical industry. Cr(VI) concentration in geogenic waters was less than 40 ppb. Anthropogenic waters contained up to 127,000 ppb Cr(VI). At both geogenic and anthropogenic sites, where known, the source of pollution had a low δ53Cr (<1‰). δ53Cr of geogenic and anthropogenic waters was up to 3.9 and 5.8‰, respectively. At both serpentinite-dominated and industrial sites, δ53Cr(VI)aq was shifted toward higher values, compared to the pollution source. At the industrial sites, this positive δ53Cr shift was related to Cr(VI) reduction, a process known to fractionate Cr isotopes. At geogenic sites, the origin of high δ53Cr(VI)aq is tentatively ascribed to preferential release of 53Cr during oxidation of soil Cr(III) and its mobilization to water. δ53Cr(VI) of industrially contaminated waters was significantly higher (p<0.001) compared to δ53Cr of waters carrying geogenic Cr (VI), implying that either the effective fractionation factor or process extent were greater for Cr(VI) reduction than for Cr(III) oxidation.
    Environmental Science & Technology 04/2014; · 5.48 Impact Factor
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    ABSTRACT: Soils in polluted regions are generally regarded as a delayed, long-lasting source for Pb contamination of aquatic systems. Lead deposited on topsoil is slowly transported downward with particulate and colloidal organic matter, driven by infiltrating precipitation. Then, Pb is tightly retained in mineral soil. Lead export from catchments is extremely low and de-coupled from the atmospheric input. We tested this hypothesis in 11 small catchments, differing in pollution levels. Input/ouput Pb fluxes were monitored for 14-15 years in an era of decreasing industrial Pb emission rates. Between 1996/1997 and 2010, Pb deposition fluxes decreased significantly, on average by 80 %. At the beginning of the monitoring, Pb export constituted 2 to 58 % of Pb input. At the end of the monitoring, Pb export constituted 2 to 95 % of Pb input. Highly polluted sites in the northeast exported significantly more Pb than less polluted sites further south. The 206Pb/207Pb isotope ratios of runoff (1.16) were identical to those of topsoil and present-day deposition, and different from mineral soil and bedrock. Lead isotope systematics and between-site flux comparisons indicated that a portion of the incoming Pb had a relatively short residence time in the catchments, on the order of decades.
    Environmental Science & Technology 03/2014; · 5.48 Impact Factor
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    ABSTRACT: Isotopic evidence for nitrogen mobility in peat bogs, Geochimica et Cosmochimica Acta (2014), doi: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
    Geochimica et Cosmochimica Acta 01/2014; · 3.88 Impact Factor
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    ABSTRACT: Here we report chromium isotope compositions, expressed as d 53/52 Cr in per mil (&) relative to NIST 979, measured in selected Cr-rich minerals and rocks formed by the primary magmatic as well as the secondary metamorphic and weathering processes. The main objectives of this study were: (i) to further constrain the isotope composition of the Earth's mantle Cr inventory and its possible variation during geological history, based on the analysis of globally distributed and stratigraph-ically constrained mantle-derived chromites; and (ii) to investigate the magnitude and systematics of Cr isotope fractionation during oxidative weathering and secondary alteration (i.e., hydration, serpentinization) of the magmatic Cr sources. Specif-ically, we analyzed d 53/52 Cr in a set of globally distributed mantle-derived chromites (FeMgCr 2 O 4 , n = 30) collected from var-ious locations in Europe, Asia, Africa and South America, and our results confirm that a chromite-hosted Earth's mantle Cr inventory is uniform at À0.079 ± 0.129& (2SD), which we named here as a 'canonical' mantle d 53/52 Cr signature. Further-more our dataset of stratigraphically constrained chromites, whose crystallization ages cover most of the Earth's geological history, indicate that the bulk Cr isotope composition of the chromite-hosted mantle inventory has remained uniform, within about ±0.100&, since at least the Early Archean times ($3500 million years ago, Ma). To investigate the systematics of Cr isotope fractionation associated with alteration processes we analyzed a number of secondary Cr-rich minerals and variably altered ultramafic rocks (i.e., serpentinized harzburgites, lherzolites) that revealed large positive d 53/52 Cr anomalies that are systematically shifted to higher values with an increasing degree of alteration and serpentinization. The degree of aqueous alteration and serpentinization was quantified by the abundances of fluid-mobile (Rb, K) elements, and by the Loss On Ignition (LOI) parameter, which determines the amount of structurally bound water (OH/H 2 O) present in secondary hydrated minerals like serpentine. Overall, we observed that altered ultramafic rocks that yielded the highest LOI values, and the lowest amounts of fluid mobile elements, also yielded the heaviest d 53/52 Cr signatures. Therefore, we conclude that secondary alteration (i.e., hydration, serpentinization) of ultramafic rocks in near-surface oxida-tive environments tend to shift the bulk Cr isotope composition of the weathered products to isotopically heavier values, pointing to a dynamic redox cycling of Cr in the Earth's crustal and near-surface environments. Hence, if validated by future
    Geochimica et Cosmochimica Acta 12/2013; 123:74-92. · 3.88 Impact Factor
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    ABSTRACT: In recent years, routine application of the stable isotope determination of chromium (Cr) in environmental and health protection research has led to the search for simpler chromite decomposition techniques. As the range of Cr isotope abundance ratios in nature is very narrow, conventional chromite decomposition techniques are no longer suitable, due to the relatively high risk of contamination during laboratory procedures. We have developed a protocol for the decomposition of chromites based on oxidation by bromic acid at room temperature. The procedure takes 15 d and requires two doses of bromic acid during the reaction period (day 1 and 8), due to the limited stability of the reagent. Chromium extracted by alkaline oxidative fusion and by bromic acid decomposition yielded statistically indistinguishable δ53Cr values, measured by multi-collector inductively coupled plasma-mass spectrometry following addition of a 50Cr-54Cr double-spike. Au cours des dernières années, l'application «en routine» de la détermination des isotopes stables du chrome (Cr) dans les recherches environnementales et de protection sanitaire a conduit à la recherche de techniques simples de décomposition de la chromite. Comme la gamme des rapports d'abondances des isotopes du Cr dans la nature est très étroite, les techniques classiques de décomposition de la chromite ne sont plus adaptées, en raison du risque de contamination relativement élevé au cours des procédures en laboratoire. Nous avons développé un protocole pour la décomposition des chromites basé sur l'oxydation par l'acide bromique à température ambiante. La procédure dure 15 jours, et nécessite deux doses d'acide bromique pendant la période de réaction (jours 1 et 8), en raison de la stabilité limitée du réactif. Les valeurs δ53Cr du Chrome, extrait par fusion alcaline oxydative et par décomposition à l'acide bromique et mesurées par spectrométrie de masse à source plasma et à multi-collection après l'addition d'un double «Spike» 50Cr-54Cr, sont statistiquement indiscernables.
    Geostandards and Geoanalytical Research 09/2013; · 3.79 Impact Factor
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    ABSTRACT: Variations in sulfur isotope ratios in lacustrine sediments are used here to reveal regional aspects of past environ-mental change at Lake Tulane, Florida, USA. Earlier studies of this late-Pleistocene/Holocene lake sediment core provided the framework for assessing some of the underlying mechanisms of change in the paleolimnology of Lake Tulane. Prior research on the lake's history identied seven phases of Pinus-dominated vegetation, interpreted as periods with warm and wet climate; intervening times were relatively cool and dry. We hypoth-esized that variations in vegetation and climate, along with deepening of the lake, might lead to temporal changes in S cycling and in δ 34 S of sulfur delivered to the sediment. The stratigraphy is characterized by a wide range of δ 34 S values (+7 to +15‰V-CDT), and a sequence of four major, extended trends in δ 34 S within the 60,000-year period. Changes in the δ 34 S prole were statistically unrelated to ve tested parameters (concentrations of S, organic matter, Al, and Fe, and local vegetation). Total sulfur concentration was positively correlated with organic matter; pyrite was not detected. The δ 34 S trends were more likely related to changes in the distance to sources of marine aerosols during the late Pleistocene and Holocene. Flux of marine aerosols (with more positive δ 34 S) would have been lowest at the Last Glacial Maximum, about 20–25,000 cal yr BP, when sea level was at least 120 m lower than present and the shorelines east and west of Florida were as much as 200 km seaward of the modern position. The δ 34 S lake sediment prole thus provides insights into past paleogeographic changes that are not evident in other geochemical or palynological data. © 2013 Published by Elsevier B.V.
    Chemical Geology 06/2013; 349-350:110-116. · 3.48 Impact Factor
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    ABSTRACT: In this study, used brewers draff was investigated as a novel sorbent for Cr(VI) and compared with other biosorbents (grape waste, peat moss, and sawdust). FTIR-ATR, BET analysis, and pH determination were used to characterize the sorbents. Kinetic and equilibrium experiments were performed, and two empirical models, Langmuir and Freundlich, were used to describe Cr adsorption. Additionally, packed bed column experiments were also performed. In order to identify possible reduction processes, ion exchange separation on the AG1-X8 resin was used to separate the anionic Cr(VI) and the reduced cationic Cr(III) from the aqueous phase after biosorption. Cr(VI) removal was pH-dependent and fitted well both the Langmuir and the Freundlich isotherm models. The ion exchange separation showed that Cr(VI) reduction had occurred in the solution during biosorption. The efficiency of draff as a biosorbent was comparable (or even higher) to highly organic materials (e.g., composted peat), showing its potential application for Cr(VI) decontamination.
    Journal of Colloid and Interface Science 04/2013; 396:227-33. · 3.55 Impact Factor
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    ABSTRACT: Nitrogen belongs to chemical elements whose biogeochemical cycles are most heavily disturbed by human activities, and large regions worlwide experience elevated depositions of reactive N (NO3-, NH4+). Peatlands contain as much as 15 % of the world's soil N. It it is unclear whether fertilizing by anthopogenic N will lead to higher storage of C in wetlands. Elevated N input may lead to both higher net primary productivity, but will also augment microbial decomposition. Here we discuss two aspects of N cycling in Sphagnum-dominated bogs in the Czech Republic, an area characterized by a steep north-south pollution gradient and high annual N deposition (60 kg ha-1). These two aspects are N inventory in 210Pb-dated peat cores, and post-depositional mobility of N in peat. We compared the N inventory in two Czech bogs, differing in pollution, with cumulative atmospheric N input. We hypothesized that the total amount of N in the peat cores would be smaller than the cumulative N input (leaching of excess N from the bog, denitrification). The two bogs were VJ (industrial north) and CB (rural south). The investigated period was 1885-2002. The total amount of N was 4020 kg ha-1 at VJ and 1530 kg ha-1 at CB. Peat in the north contained 2.6 times more N than in the south. Historical rates of N deposition in the Czech Republic are well known (numerous papers by Kopacek). To estimate cumulative N inputs into the bogs, we also used the monthly N depositions between 1994 and 2002, measured in two nearby catchments. The estimated cumulative atmospheric N input was 1350 kg ha-1 at VJ, and 530 kg ha-1 at CB. In both cases, the amount of N found in peat was 3 times higher than the estimated atmospheric N input. Such high storage of N in peat is surprising. Post-depositional mobility of N may help to explain the discrepancies between atmospheric N inputs and N storage in peat. We found two-fold evidence for post-depositional mobility of N. Maximum N concentrations at VJ were observed in layers dated at 1950, whereas pollution level increased up to 1980, and dropped thereafter. At the end of an 18-month reciprocal peat transplant experiment between VJ and CB, we found that N isotope ratios N converged to the host site. The magnitude of the isotope change was 3 per mil, the affected depth was 10 cm. Our results are consistent with the concept of Lamers et al. (2000) in that both ^15N and the found shift in N peaks downcore confirmed removal of N from surface moss under high N depositions. On the other hand, the excess of stored N relative to the cumulative N input remains unexplained, and merits further study.
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    ABSTRACT: Little is known about atmospheric input of beryllium (Be) into ecosystems, despite its highly toxic behavior. For three consecutive winters (2009-2011), we measured Be concentrations in horizontal deposition (rime) and vertical deposition (snow) at 10 remote mountain-top locations in the Czech Republic, Central Europe. Beryllium was determined both in filtered waters, and in HF digests of insoluble particles. Across the sites, soluble Be concentrations in rime were 7 times higher, compared to snow (6.1 vs. 0.9ng·L(-1)). Rime scavenged the pollution-rich lower segments of clouds. The lowest Be concentrations were detected in the soluble fraction of snow. Across the sites, 34% of total Be deposition occurred in the form of soluble (bioavailable) Be, the rest were insoluble particles. Beryllium fluxes decreased in the order: vertical dry deposition insoluble>vertical dry deposition soluble>horizontal deposition soluble>vertical wet deposition insoluble>vertical wet deposition soluble>horizontal deposition insoluble. The average contributions of these Be forms to total deposition were 56, 21, 8, 7, 5 and 3%, respectively. Sites in the northeast were more Be-polluted than the rest of the country with sources of pollution in industrial Silesia.
    Science of The Total Environment 10/2012; 439C:26-34. · 3.16 Impact Factor
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    ABSTRACT: Slightly elevated concentrations of toxic species in waters sampled in the surroundings of a leaky landfill may be both a sign of an approaching contaminant plume, or a result of water-rock interaction. Isotopes can be instrumental in distinguishing between anthropogenic and geogenic species in groundwater. We studied sulfur and lead isotope ratios at an abandoned industrial-waste landfill, located in a densely populated part of Central Europe. Stable isotope variability in space and time was used to follow the movement of a groundwater plume, contaminated with toxic metals (Cd, Cr, Be), in fractured granitoids. Toxic metals had been mobilized from industrial waste by a strong pulse of sulfuric acid, also deposited in the landfill. Both tracers exhibited a wide range of values (δ(34)S between +2.6 and +18.9‰; (206)Pb/(207)Pb between 1.16 and 1.39), which facilitated identification of mixing end-members, and made it possible to assess the sources of the studied species. In situ fractionations did not hinder source apportionment. Influx of contaminated groundwater was observed neither in irrigation wells in a nearby village, nor at distances greater than 300m from the landfill. Combination of stable isotope tracers can be used as part of an early-warning system in landscapes affected by landfills.
    Journal of hazardous materials 07/2012; 235-236:54-61. · 4.33 Impact Factor
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    ABSTRACT: Here we report chromium isotope compositions, expressed as δ53Cr relative to NIST 979, measured in selected Cr-bearing geological materials formed by igneous, hydrothermal and metamorphic processes. The δ53Cr variations were determined by MC-ICP-MS (NEPTUNE and Isoprobe P) using a double spike enriched in 50Cr and 54Cr. Specifically, we analyzed δ53Cr in chromite deposits sampled from mafic/ultramafic igneous complexes in Europe (Norway, Austria, Poland, Cyprus, Turkey), Russia (Ural), Kazakhstan (Chromtau), New Caledonia (Tiebaghi), Cuba (Rio Cayo Guam), and South Africa (Bushveld Complex). These globally distributed chromite deposits share a uniform Cr isotope composition with an average δ53Cr of 0.050±0.182% (2SD, n = 19), with respect to the NIST 979 that yielded -0.006±0.172% (n = 32). Considering that most of the Cr used in industry is produced from these large chromite deposits, their bulk δ53Cr signature of ~0% thus represents an important reference point for the environmental studies investigating Cr contamination related to industrial sources. In contrast, samples of hydrothermal lead chromates, i.e. crocoites (PbCrO4), collected in Germany (Calenberg), Russia (Beresovsk), Brazil (Minas Gerais), and Tasmania (Dundas), yielded heavier δ53Cr signatures spanning from 0.115±0.181% up to 2.071±0.151%. The heavy Cr isotope enrichment found in crocoites is in agreement with the results of Schoenberg et al. (2008, Chem. Geol. 249, 294-306). Interestingly, a crocoite specimen from 'Beresovsk' analyzed by the latter study gave δ53Cr of 1.007±0.049%, which is identical with our analysis of a crocoite from the same locality that yielded δ53/52Cr of 1.046±0.086%. As to the alteration products of mafic/ultramafic rocks, a sample of serpentinite from Slovakia (Dobsina) showed slightly heavier δ53Cr signature of 0.248±0.055%, compared to a 'primary' mantle-derived chromium (δ53Cr ≈ 0%), suggesting that metamorphism and aqueous alteration can induce a considerable Cr isotope fractionation. This seems to be corroborated by the analysis of other post-metamorphic/hydrothermal Cr-rich minerals, such as chrome-tremolite and chrome-diopside (Finland), which both gave heavy δ53Cr values of 0.250±0.119% and 0.608±0.010%, respectively. A similarly heavy δ53Cr value of 0.515±0.122% was measured in a sample of chrome chalcedony from an ultramafic intrusion in Western Australia (Newman). On the other hand, a sample of stichtite (Morocco, Bou Azzer), which is formed as an alteration product in serpentines, gave a 'mantle-like' δ53Cr signature of 0.038±0.123%. One possible explanation for the heavy isotope enrichments of Cr-bearing minerals from metamorphic-hydrothermal systems, is that a portion of the dissolved Cr present in a mineral-forming fluid was reduced to Cr (III), prior to the formation of a mineral, causing a shift of the residual Cr in the fluid towards heavier δ53Cr (cf. Schoenberg et al. 2008). Alternatively, the δ53Cr of the metamorphic-hydrothermal fluid was already heavy at the time of the fluid formation, due to preferential partitioning of the isotopically heavy Cr(VI) into the fluid at the mineral-water interface.
    AGU Fall Meeting Abstracts. 12/2011;
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    ABSTRACT: The biogeochemical cycles of most toxic metals have been significantly altered by anthropogenic activities. Anaerobic, rain-fed organic soils are believed to record historical changes in atmospheric pollution. Suspected postdepositional mobility of trace elements, however, hinders the usefulness of peat bogs as pollution archives. To lower this uncertainty, we quantified the mobility of six trace metals in peat during an 18-month field manipulation. A replicated, reciprocal peat transplant experiment was conducted between a heavily polluted and a relatively unpolluted peatland, located 200 km apart in the Czech Republic (Central Europe). Both peatlands were Sphagnum-derived, lawn-dominated, and had water table close to the surface. A strikingly different behavior was observed for two groups of elements. Elements of group I, Fe and Mn, adjusted their abundances and vertical patterns to the host site, showing an extremely high degree of mobility. In contrast, elements of group II, Pb, Cu, Zn, and Ti, preserved their original vertical patterns at the host site, showing a high degree of immobility. Our experimental results suggest that not just lead, but also copper and zinc concentration profiles in peat are a reliable archive of temporal pollution changes within a wide pH range (2.5-5.8).
    Environmental Science & Technology 08/2011; 45(17):7180-7. · 5.48 Impact Factor
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    ABSTRACT: The soils adjacent to an area of historical mining, ore processing and smelting activities reflects the historical background and a mixing of recent contamination sources. The main anthropogenic sources of metals can be connected with historical and recent mine wastes, direct atmospheric deposition from mining and smelting processes and dust particles originating from open tailings ponds. Contaminated agriculture and forest soil samples with mining and smelting related pollutants were collected at different distances from the source of emission in the Pb-Zn-Ag mining area near Olkusz, Upper Silesia to (a) compare the chemical speciation of metals in agriculture and forest soils situated at the same distance from the point source of pollution (paired sampling design), (b) to evaluate the relationship between the distance from the polluter and the retention of the metals in the soil, (c) to describe mineralogy transformation of anthropogenic soil particles in the soils, and (d) to assess the effect of deposited fly ash vs. dumped mining/smelting waste on the mobility and bioavailability of metals in the soil. Forest soils are much more affected with smelting processes than agriculture soils. However, agriculture soils suffer from the downward metal migration more than the forest soils. The maximum concentrations of Pb, Zn, and Cd were detected in a forest soil profile near the smelter and reached about 25 g kg(- 1), 20 g kg(- 1) and 200 mg kg(- 1) for Pb, Zn and Cd, respectively. The metal pollutants from smelting processes are less stable under slightly alkaline soil pH then acidic due to the metal carbonates precipitation. Metal mobility ranges in the studied forest soils are as follows: Pb > Zn ≈ Cd for relatively circum-neutral soil pH (near the smelter), Cd > Zn > Pb for acidic soils (further from the smelter). Under relatively comparable pH conditions, the main soil properties influencing metal migration are total organic carbon and cation exchange capacity. The mobilization of Pb, Zn and Cd in soils depends on the persistence of the metal-containing particles in the atmosphere; the longer the time, the more abundant the stable forms. The dumped mining/smelting waste is less risk of easily mobilizable metal forms, however, downward metal migration especially due to the periodical leaching of the waste was observed.
    Environmental Monitoring and Assessment 06/2011; 184(4):2517-36. · 1.68 Impact Factor
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    ABSTRACT: Plant-available reserves of major base cations, Ca2+ and Mg2+, decreased markedly in soils over the past century, thus posing a potential threat to forest ecosystem health. Trees are thought to obtain dissolved Ca2+ ions mainly from an easily accessible soil–water reservoir also termed the ‘exchangeable cation pool’. The status of Ca reserves in this soil pool is sensitive to anthropogenic perturbations such as soil acidification induced by acid rain and/or excessive timber harvesting. Here we show that in a base-poor forest of the northeastern USA (i.e. Wachusett Mountain, Massachusetts) the ‘exchangeable Ca pool’ of deeper mineral soils has a unique isotope signature that is significantly enriched in the radiogenic 40Ca, due to the dissolution of K-rich silicate minerals such as biotite. Using a simple isotope mass balance, and assuming that the input of Ca from biotite has a εCa signature of ∼16, the results of our calculation indicate that the weathering of biotite may supply a sizeable fraction, up to 25%, of Ca2+ ions into the ‘exchangeable cation pool’ of deeper mineral soils. Importantly, samples of local vegetation (i.e. woody tissues of red oak) show no detectable excess of the radiogenic 40Ca, and based on our model the upper limit of a possible biotite-derived Ca contribution in vegetation is estimated at ∼5%. We also found no evidence of the radiogenic 40Ca signal in the samples of forest floor and the uppermost organic-rich soils (0–15cm depth), which in turn suggest that over the long-term development of the forest and its organic matter accumulation, the vegetation growth must have also relied primarily on the non-radiogenic Ca sources. Based on our experimental data, such sources may include (i) wet atmospheric deposition, (ii) the organically-complexed Ca in topsoil horizons, and (iii) chemical weathering and/or fungal-mediated dissolution of apatite and Ca-rich plagioclase. Hence, our stable and radiogenic Ca isotope data indicate that the studied base-poor forest is able to bypass the ‘exchangeable cation pool’ of deeper (i.e. below 15cm) mineral soils, and still manages to meet its nutritional requirements with respect to Ca. Another important implication of this study is that the organically-complexed Ca in the topsoil horizon (0–15cm depth) has to be tightly bound to the ion exchange sites, otherwise the large radiogenic 40Ca signatures present in the ‘exchangeable cation pool’ of deep mineral soils would be swamped by the downward gravitational flux of non-radiogenic Ca from the decaying organic matter and litterfall. Hence, the limited mobility of the organically-complexed Ca in soils and its tight biological cycling could explain the lack of a significant impact of vegetation on the Ca isotope systematics observed in large rivers.
    Geochimica et Cosmochimica Acta 01/2011; 75(22):7031-7046. · 3.88 Impact Factor
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    ABSTRACT: Due to high availability of adsorption sites, forested catchments could be net sinks for pollutant arsenic both during the period of increasing and decreasing pollution. We tested this hypothesis along a north-south pollution gradient in spruce die-back affected areas of Central Europe. For two water years (2007-2008), we monitored As fluxes via spruce-canopy throughfall, open-area precipitation, and runoff in four headwater catchments (Czech Republic). Since 1980, atmospheric As inputs decreased 26 times in the north, and 13 times in the south. Arsenic export by runoff was similar to atmospheric inputs at three sites, resulting in a near-zero As mass balance. One site exhibited a net export of As (2.2 g ha(-1) yr(-1)). In contrast, the preceding period (1995-2006) showed much higher As fluxes, and higher As export. Czech catchments do not serve as net sinks of atmospheric As. A considerable proportion of old industrial arsenic is flushed out of the soil.
    Environmental Pollution 10/2010; 159(1):204-11. · 3.73 Impact Factor
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    ABSTRACT: The 40-year long period of heavy industrialization in Central Europe (1950-1990) was accompanied by burning of arsenic-rich lignite in thermal power plants, and accumulation of anthropogenic arsenic in forest soils. There are fears that retreating acidification may lead to arsenic mobilization into drinking water, caused by competitive ligand exchange. We present monthly arsenic concentrations in surface runoff from 12 headwater catchments in the Czech Republic for a period of 13 years (1996-2008). The studied area was characterized by a north-south gradient of decreasing pollution. Acidification, caused mainly by SOx and NOx emissions from power plants, has been retreating since 1987. Between 1996 and 2003, maximum arsenic concentrations in runoff did not change, and were < 1 ppb in the rural south and < 2 ppb in the industrial north. During the subsequent two years, 2004-2005, maximum arsenic concentrations in runoff increased, reaching 60% of the drinking water limit (10 ppb). Starting in 2006, maximum arsenic concentrations returned to lower values at most sites. We discuss three possible causes of the recent arsenic concentration maximum in runoff. We rule out retreating acidification and a pulse of high industrial emission rates as possible controls. The pH of runoff has not changed since 1996, and is still too low (<6.5) at most sites for an As-OH(-) ligand exchange to become significant. Elevated arsenic concentrations in runoff in 2004-2005 may reflect climate change through changing hydrological conditions at some, but not all sites. Dry conditions may result in elevated production of DOC and sulfur oxidation in the soil. Subsequent wet conditions may be accompanied by acidification leading to faster dissolution of arsenic-bearing sulfides, dissolution of arsenic-bearing Fe-oxyhydroxides, and elevated transport of arsenic sorbed on organic matter. Anaerobic domains exist in normally well-aerated upland soils for hours-to-days following precipitation events.
    Science of The Total Environment 08/2010; 408(17):3614-22. · 3.16 Impact Factor
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    ABSTRACT: Annual growth rings of a common hardwood species, Picea abies L., were investigated as a potential archive of past atmospheric Pb pollution. Wide distribution of trees in terrestrial settings and straightforward chronology are two advantages of this potential geochemical archive, but several processes described in the literature may obscure the trends in past Pb deposition. These confounding factors include, e.g., radial post-depositional mobility of Pb in xylem, and ecosystem acidification leading to higher bioavailability of Pb. One- to five-year annual wood increments were analyzed for Pb concentrations and 206Pb/207Pb ratios at Jezeri (JEZ), Uhlirska (UHL) and Na Lizu (LIZ), three sites in the Czech Republic, differing in atmospheric Pb loads. Three to four trees per site were included in the study. Distinct Pb concentration maxima between 1960 and 1990 at the two heavily polluted sites (JEZ and UHL) coincided with historical Pb emissions known from inventories of industrial production. No Pb concentration maxima were found at one site, LIZ, situated in a national park 150 km from major pollution sources. Spruce tree rings from JEZ, located just 5 km from coal-burning power stations, contained a large proportion of coal-derived Pb (a high-206Pb/207Pb ratio of 1.19). A coal-related maximum in 206Pb/207Pb in JEZ tree rings was found using two different analytical techniques, laser-ablation multi-collector ICP MS, and single-collector sector-field ICP MS. In a three-isotope graph (206Pb/207Pb vs. 208Pb/207Pb), tree-ring data plotted into the field of ombrotrophic (i.e., rain-fed) peat bogs, suggesting negligible contribution of bedrock-derived Pb in the xylem. We concluded that none of the potential confounding factors played a major role at our sites. Annual growth rings of P. abies in Central Europe faithfully recorded historical changes in atmospheric Pb depositions.
    Geochimica et Cosmochimica Acta 08/2010; · 3.88 Impact Factor

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618 Citations
145.31 Total Impact Points


  • 1992–2013
    • Czech Geological Survey
      Praha, Praha, Czech Republic
  • 2010
    • University of Bergen
      Bergen, Hordaland, Norway
  • 2008
    • Umeå University
      • Department of Ecology and Environmental Science
      Umeå, Vaesterbotten, Sweden
  • 2007
    • Institute of Chemical Technology Prague
      • Department of Chemistry of Solid State
      Praha, Hlavni mesto Praha, Czech Republic
    • Centre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement
      Aix, Provence-Alpes-Côte d'Azur, France
  • 2000–2005
    • CSU Mentor
      Long Beach, California, United States
  • 1992–2003
    • Villanova University
      • Department of Biology
      Norristown, PA, United States
  • 1995–2001
    • University of Leeds
      • School of Earth and Environment
      Leeds, England, United Kingdom