The long-term effects of the Central Atlantic Magmatic Province, a large igneous province connected to the end-Triassic mass-extinction (201.5 Ma), remain largely elusive. Here, we document the ...persistence of volcanic-induced mercury (Hg) pollution and its effects on the biosphere for ~1.3 million years after the extinction event. In sediments recovered in Germany (Schandelah-1 core), we record not only high abundances of malformed fern spores at the Triassic-Jurassic boundary, but also during the lower Jurassic Hettangian, indicating repeated vegetation disturbance and stress that was eccentricity-forced. Crucially, these abundances correspond to increases in sedimentary Hg-concentrations. Hg-isotope ratios (δ
Hg, Δ
Hg) suggest a volcanic source of Hg-enrichment at the Triassic-Jurassic boundary but a terrestrial source for the early Jurassic peaks. We conclude that volcanically injected Hg across the extinction was repeatedly remobilized from coastal wetlands and hinterland areas during eccentricity-forced phases of severe hydrological upheaval and erosion, focusing Hg-pollution in the Central European Basin.
Mercury is a ubiquitous environmental pollutant of dominantly anthropogenic origin. A critical concern for human health is the introduction of mercury to the food chain; therefore, monitoring of ...mercury levels in agricultural soil is essential. Unfortunately, the total mercury content is not sufficiently informative as mercury can be present in different forms with variable bioavailability. Since 1990, the use of bioreporters has been investigated for assessment of the bioavailability of pollutants; however, real contaminated soils have rarely been used in these studies. In this work, a bioassay with whole-cell bacterial bioreporter
ARL1 was used for estimation of bioavailable concentration of mercury in 11 soil samples. The bioreporter emits bioluminescence in the presence of Hg(II). Four different pretreatments of soil samples prior to the bioassay were tested. Among them, laccase mediated extraction was found to be the most suitable over water extraction, alkaline extraction, and direct use of water-soil suspensions. Nevertheless, effect of the matrix on bioreporter signal was found to be severe and not possible to be completely eliminated by the method of standard addition. In order to elucidate the matrix role, influences of humic acid and selected metal ions present in soil on the bioreporter signal were tested separately in laboratory solutions. Humic acids were found to have a positive effect on the bioreporter growth, but a negative effect on the measured bioluminescence, likely due to shading and Hg binding resulting in decreased bioavailability. Each of the tested metal ions solutions affected the bioluminescence signal differently; cobalt (II) positively, iron (III) negatively, and the effects of iron (II) and nickel (II) were dependent on their concentrations. In conclusion, the information on bioavailable mercury estimated by bioreporter
ARL1 is valuable, but the results must be interpreted with caution. The route to functional bioavailability bioassay remains long.
Willows, woody plants of genus
Salix
common in floodplains of temperate regions, act as plant pumps and translocate the Cd and Zn in the soil profiles of uncontaminated and weakly contaminated ...floodplains from the sediment bulk to the top strata. We suggest this process occurs because the Cd and Zn concentrations in willow leaves exceed those in the sediments. Senescing foliage of plant species common in floodplains can increase the Cd and Zn ratios as compared to other elements (Pb and common ‘lithogenic elements’ such as Al) in the top strata of all floodplains, including those that have been severely contaminated. The top enrichment is caused by the root uptake of specific elements by growing plants, which is followed by foliage deposition. Neither the shallow groundwater nor the plant foliage shows that Cd, Zn, and Pb concentrations are related to those in the sediments, but they clearly reflect the shallow groundwater pH, with the risk element mobilised by the acidity that is typical for the subsurface sediments in floodplains. The effect that plants have on the Pb in floodplains is significantly lower than that observed for Cd and Zn, while U can be considered even less mobile than Pb. Groundwater and plant leaves can contribute to secondary contamination with Cd and Zn from floodplain pollution hotspots, meaning that plants can accumulate these elements on the floodplain surface or even return them back to the fluvial transport, even if bank erosion would not occur. For Pb and U at the sites studied, these risks were negligible.
The Podgórze uranium deposit is located near Kowary in the Sudetes Mountains, SW Poland. The mine is located in the Karkonosze-Izera block, largely comprising Cambrian to Devonian metamorphic rocks ...intruded by the Variscan Karkonosze granite. Uranyl minerals from the Podgórze mine can be divided into three assemblages. The first one is associated with heavily ventilated mining galleries. The next assemblage is related to the outflow of water from fissures in the walls of the mine galleries. The last assemblage appears in the mine dump, where there is increased activity of other weathering products. The main purpose of this paper is to determine the mineralogical characteristics of uranyl minerals from the abandoned Podgórze uranium mine and reconstruct the physicochemical crystallization conditions based on the concentrations of rare earth elements (REEs) in these minerals. The results of thermodynamic modeling show that the aqueous species of uranyl ion in the mine water are represented by UO2HAsO4 (aq), UO2CO3(OH)3−, UO2CO3 (aq), and UO2OH+. The content of REEs and their distribution patterns were used to determine the crystallization conditions of uranyl minerals. Uranyl carbonates and arsenates have generally low concentrations of REEs compared to uranyl silicates, phosphates, and hydroxides, which have higher concentrations. The differences in REE concentration patterns may be related with the oxidizing nature of water circulating in the subsurface part of the deposit.
Our study addressed mercury contamination hotspots that originated from Chemical Factory Marktredwitz, Germany. The factory was abandoned in 1985 but its legacy has been persistently endangering the ...river ecosystem of the Ohře River, a Labe (Elbe) River tributary in the Czech Republic. We identified the timing for the peak contamination of fine sediments entering the Skalka Reservoir located on the Ohře River downstream of the Czech German boundary. Age constraints for the reservoir sediments were obtained using gamma spectrometry analyses of 137Cs and unsupported (excess) 210Pb. We also summarised historical and current Hg concentrations in suspended particulate matter in the Kössein–Röslau–Ohře river system and recent Hg concentrations in aquatic plants. Secondary contamination and its transfer to the Czech stretch of the Ohře River and the Skalka Reservoir through severely contaminated suspended material peaked during the period of factory closure and the start of remediation. The Hg contamination import to the Czech Republic is not likely to improve if the river is left without traditional management of bank reinforcement. This case study highlights a gap in safety regulations for the management of severely contaminated rivers and demonstrates the need to consider the role of historical contamination in river ‘renaturation’.
Methods commonly used for soil sample preparation may be unsuitable for measuring Hg concentrations due to the possible loss of volatile Hg species when drying at higher temperatures. Here, the ...effects of freeze-drying, air drying at 25°C and oven-drying at 105°C on Hg concentrations in two soil types and three standard reference materials were tested. Two soils with different levels of Hg contamination and three reference materials were examined. A systematic decrease of Hg concentrations was observed in air-dried (24 %) and oven-dried (3 %) contaminated upland soils in comparison to freeze-dried control samples. The 105°C oven drying also led to loss of Hg from reference materials (5 %–8 % in comparison with the certified Hg concentration). Different results from the drying of sterilized reference materials and natural soils were probably related to the extent of microbiological activity, demonstrating the importance of this parameter in sample preparation for Hg analysis.
Naturally contaminated soil, sediment and water at the Mokrsko-West gold deposit, Central Bohemia, have been studied in order to determine the processes that lead to release of As into water and to ...control its speciation under various redox conditions. In soils, As is bonded mainly to secondary arseniosiderite, pharmacosiderite and Fe oxyhydroxides and, rarely, to scorodite; in sediments, As is bonded mainly to Fe oxyhydroxides and rarely to arsenate minerals.
The highest concentrations of dissolved As were found in groundwater (up to 1141 μg L
−
1
), which mostly represented a redox transition zone where neither sulphide minerals nor Fe oxyhydroxide are stable. The main processes releasing dissolved As in this zone are attributed to the reductive dissolution of Fe oxyhydroxides and arsenate minerals, resulting in a substantial decrease in their amounts below the groundwater level. Some shallow subsurface environments with high organic matter contents were characterized by reducing conditions that indicated a relatively high amount of S
−
2,0
in the solid phase and a lower dissolved As concentration (70–80 μg L
−
1
) in the pore water. These findings are attributed to the formation of Fe(II) sulphides with the sorbed As. Under oxidizing conditions, surface waters were undersaturated with respect to arsenate minerals and this promoted the dissolution of secondary arsenates and increased the As concentrations in the water to characteristic values from 300 to 450 μg L
−
1
in the stream and fishpond waters. The levels of dissolved As(III) often predominate over As(V) levels, both in groundwaters and in surface waters. The As(III)/As(V) ratio is closely related to the DOC concentration and this could support the assumption of a key role of microbial processes in transformations of aqueous As species as well as in the mobility of As.
The history and continuity of lowland woodlands in Central Europe is closely connected with human activities. We studied a small wetland situated directly in a low-elevation oak-dominated woodland to ...evaluate the history and impact of humans on an oak woodland in south-eastern Slovakia. We used different proxies to obtain evidence of woodland history spanning at least 8,500 years. Pollen, diatom and physical analysis, including micromorphology, were used to study infill sediments and to determine the processes causing the influx of material into the wetland basin from its surroundings. The oak-dominated woodland community occurred throughout the Holocene, but its detailed history is impossible to trace because of reverse chronology caused by mixing of deposits. The stability of the oak woodland was determined by anthropogenic disturbances such as grazing. These disturbances are indicated by pollen taxa, signals of soil erosion in the deposits, and local development of the wetland that acted as drinking and hemp retting basin. The recent decline of human pressure has led to gradual changes in the species composition of the wetland itself (shrub encroachment) and of understory of the surrounding oak woodlands.
A method for the determination of total sulfur in geological materials by inductively coupled plasma‐optical emission spectrometry (ICP‐OES) is described. We show that good results were obtained ...using this method even for sample types with very low (< 20 μg g−1) sulfur concentration (e.g., peridotite). Sulfur was determined in fifteen geological reference materials with different sulfur contents. For reference materials with certified sulfur contents, the ICP‐OES method gave results in excellent agreement with certified values, and uncertainties better than 4% RSD. ICP‐OES results for sulfur in other reference materials yielded RSDs better than 10%, where S concentrations were > 100 μg g−1 (except for diabase W‐2a, 16% RSD). Reference materials with lower sulfur contents (< 40 μg g−1) showed much higher RSDs (17–18%). Except for RMs with certified values for sulfur, most data obtained by the combustion infrared detection method generally showed higher concentrations than those measured by ICP‐OES and a better RSD (≤ 8% for all materials except DTS‐2b).
Une méthode pour la détermination du soufre total dans les matériaux géologiques utilisant la spectrométrie d’émission optique couplée à un plasma inductif (ICP‐OES) est décrite. Nous montrons que de bons résultats ont été obtenus en utilisant cette méthode, même pour les échantillons à très faible (< 20 μg g−1) concentration en soufre (par exemple, la péridotite). Le soufre a été mesuré dans une quinzaine de matériaux géologiques de référence caractérisés par des teneurs en soufre différentes. Pour les matériaux de référence avec des teneurs certifiés en soufre, la méthode ICP‐OES a donné des résultats en excellent accord avec les valeurs certifiées, avec des incertitudes meilleures que 4% RSD. Les résultats ICP‐OES pour le soufre dans les autres matériaux de référence ont donné des RSD meilleurs que 10%, lorsque la concentration en S était > 100 μg g−1 (sauf pour la diabase W‐2a, RSD de 16%). Les matériaux de référence à faible teneur en soufre (< 40 μg g−1) ont donné des RSD beaucoup plus élevés (17–18%). Sauf pour RMs avec les valeurs certifiées, la plupart des données obtenues par la méthode par combustion et détection infrarouge ont généralement montré des concentrations plus élevées que celles mesurées par ICP‐OES et un meilleur RSD (≤ 8% pour tous les matériaux sauf DTS‐2b).
The area of the Black Triangle has been exposed to extreme levels of acid deposition in the twentieth century. The chemical weathering of sandstones found within the Black Triangle became well-known ...phenomenon. Infiltration of acid rain solutions into the sandstone represents the main input of salt components into the sandstone. The infiltrated solutions–sandstone percolates–react with sandstone matrix and previously deposited materials such as salt efflorescence. Acidic sandstone percolates pH 3.2–4.8 found at ten sites within the National Park Bohemian Switzerland contained high Al-tot (0.8–10 mg L
−1
) concentrations and high concentrations of anions SO
4
(5–66 mg L
−1
) and NO
3
(2–42 mg L
−1
). A high proportion (50–98 %) of Al-tot concentration in acid percolates was represented by toxic reactive Al
n+
. Chemical equilibrium modeling indicated as the most abundant Al species Al
3+
, AlSO
4
+
, and AlF
2+
. The remaining 2–50 % of Al-tot concentration was present in the form of complexes with dissolved organic matter Al-org. Mobilization and transport of Al from the upper zones of sandstone causes chemical weathering and sandstone structure deterioration. The most acidic percolates contained the highest concentrations of dissolved organic material (estimated up to 42 mg L
−1
) suggesting the contribution of vegetation on sandstone weathering processes. Very low concentrations of Al-tot in springs at BSNP suggest that Al mobilized in unsaturated zone is transported deeper into the sandstone. This process of mobilization could represent a threat for the water quality small-perched aquifers.
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