[show abstract][hide abstract] 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
[show abstract][hide abstract] 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
[show abstract][hide abstract] 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; · 2.00 Impact Factor
[show abstract][hide abstract] 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. · 3.17 Impact Factor
[show abstract][hide abstract] 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.
[show abstract][hide abstract] 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. · 3.26 Impact Factor
[show abstract][hide abstract] 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. · 4.14 Impact Factor
[show abstract][hide abstract] 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.
[show abstract][hide abstract] 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).
[show abstract][hide abstract] 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. · 1.59 Impact Factor
[show abstract][hide abstract] 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
[show abstract][hide abstract] 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.
[show abstract][hide abstract] 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. · 3.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: An 18-month reciprocal peat transplant experiment was conducted between two peatlands in the Czech Republic. Both sites were 100% Sphagnum-covered, with no vascular plants, and no hummocks and hollows. Atmospheric depositions of sulfur were up to 10 times higher at the northern site Velke jerabi jezero (VJJ), compared to the southern site Cervene blato (CB). Forty-cm deep peat cores, 10-cm in diameter, were used as transplants and controls in five replicates. Our objective was to evaluate whether CO2 and CH4 emissions from Sphagnum peat bogs are governed mainly by organic matter quality in the substrate, or by environmental conditions. Emission rates and δ13C values of CO2 and CH4 were measured in the laboratory at time t=18 months. All measured parameters converged to those of the host site, indicating that, at least in the short-term perspective, environmental conditions were a more important control of greenhouse gas emissions than organic carbon quality in the substrate. Since sulfate reducers outcompete methanogens, we hypothesized that the S-polluted site VJJ should have lower methane emissions than CB. In fact, the opposite was true, with significantly (p13C profiles in peat agree. A high degree of within-site homogeneity in δ13C was found. When a specific vertical δ13C trend was seen in one peat core, the same trend was also seen in all the remaining peat cores from the wetland. The δ13C value increased downcore at both CB and VJJ. At VJJ, however, 20 cm below surface, a reversal to lower δ13C downcore was seen. Based on 210Pb dating, peat at 20-cm depth at VJJ was only 15 years old. Increasing δ13C values in VJJ peat accumulated between 1880–1990 could not be caused by assimilation of atmospheric CO2 gradually enriched in the light isotope 12C due to fossil fuel burning. Rather they were a result of a combination of isotope fractionations accompanying assimilation and mineralization of Sphagnum C. These isotope fractionations may record information about past changes in C storage in wetlands.
[show abstract][hide abstract] 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.
[show abstract][hide abstract] ABSTRACT: Search for a biogeochemical archive of past sulfur pollution is motivated by the need to predict ecosystem health. Sofar, no indicator of local-scale S pollution has existed, while long-range transport of S can already be studied using polar ice records. One archive of S pollution in temperate climate zones could be annual growth rings of trees. However, S concentration patterns in tree rings of most species have been unknown because of negligible S accumulation in wood. We modified a wet chemistry procedure to increase the recovery of S from tree rings, and report time series of S concen-trations in six trees from an acidified, spruce die-back affected area of Central Europe. Beech tree rings, despite 4 times lower atmospheric S inputs, exhibited twice higher S concentration in wood than spruce. The period of peak industrial S pollution of the 1980s did not result in enhanced S accumulation in tree rings of either species. Physiological processes rather than S abundance in the ecosystem regulate S storage in tree rings. in wood biomass, due to the fact that the amount of S in tree rings is extremely low (Yang et al., 1996, Giesemann et al., 2005, Kawamura et al., 2006). Sofar, it has been unclear whether S concentrations in tree rings in spruce-die back areas reflect the changing availability of anthro-pogenic sulfur, and thus can be used as an archive of past environmental change. Previous studies showed that high atmospheric SO 2 input results in elevated S concentration in leaves, mainly in the form of sulfate (Giesemann et al., 2000). Similarly, S concentration in organic soil horizons under spruce canopy is positively correlated with the atmospheric S inputs along an east-west pollution gradient across Eu-rope (Novak et al., 2001). We hypothesized that the de-gree of sulfate assimilation and storage of sulfur in an-nual growth rings of hardwoods would parallel temporal changes in industrial S emissions in Central Europe. We measured S concentrations in tree rings of three Norway spruce and three European beech trees from a forest die-back affected site in the northern Czech Republic. The biomass data were complemented with a year-long moni-toring of atmospheric S deposition into both stands. Our objective was to evaluate whether trees were passive stores of assimilated sulfur. If so, the species receiving higher S input from atmospheric deposition would dis-play the greatest enrichment of S in annual growth rings.
[show abstract][hide abstract] ABSTRACT: An 18-month reciprocal peat transplant experiment was conducted between two peatlands in the Czech Republic. Both sites were 100% Sphagnum-covered, with no vascular plants, and no hummocks and hollows. Atmospheric depositions of sulfur were up to 10 times higher at the northern site Velke jerabi jezero (VJJ), compared to the southern site Cervene blato (CB). Forty-cm deep peat cores, 10 cm in diameter, were used as transplants and controls in five replicates. Our objective was to evaluate whether CO2 and CH4 production potentials in Sphagnum peat bogs are governed mainly by organic matter quality, or by environmental conditions. Production rates and δ13C values of CO2 and CH4 were measured in the laboratory at time t=18 months. All measured parameters converged to those of the host site, indicating that, at least in the short-term perspective, environmental conditions were a more important control of greenhouse gas emissions than organic carbon quality. Since sulfate reducers outcompete methanogens, we hypothesized that the S-polluted site VJJ should have lower methane emissions than CB. In fact, the opposite was true, with higher methane emissions from VJJ. As a first step in an effort to link C isotope composition of emitted gases and residual peat substrate, we determined whether multiple vertical δ13C profiles in peat agree. A high degree of within-site homogeneity in δ13C was found. The δ13C value increased downcore at both CB and VJJ. However, 20 cm below surface, a reversal to lower δ13C downcore was seen at VJJ. Based on 210Pb dating, peat at 20 cm depth at VJJ was only 15 years old. Increasing δ13C values in VJJ peat accumulated between 1880–1990 could not be caused by assimilation of atmospheric CO2 gradually enriched in the light isotope 12C due to fossil fuel burning.