Sizeable net export of base cations from a Carpathian flysch catchment indicates their geogenic origin while the 26Mg/24Mg, 44Ca/40Ca and 87Sr/86Sr isotope ratios in runoff are indistinguishable from atmospheric input.

Nutrient imbalances may negatively affect the health status of forests exposed to multiple stress factors, including drought and bark beetle calamities. We studied the origin of base cations in runoff from a small Carpathian catchment underlain by base-poor flysch turbidites using magnesium (Mg), calcium (Ca) and strontium (Sr) isotope composition of 10 ecosystem compartments. Our objective was to constrain conclusions drawn from long-term hydrochemical monitoring of inputs and outputs. Annual export of Mg, Ca and Sr exceeds 5-to-15 times their atmospheric input. Mass budgets per se thus indicate sizeable net leaching of Mg, Ca and Sr from bedrock sandstones and claystones. Surprisingly, δ26Mg, δ44Ca and 87Sr/86Sr isotope ratios of runoff were practically identical to those of atmospheric deposition and soil water but significantly different from bedrock isotope ratios. We did not find any carbonates in the studied area as a hypothetical, easily dissolvable source of base cations whose isotope composition might corroborate the predominance of geogenic base cations in the runoff. Marine carbonates typically have lower δ26 Mg and 87Sr/86Sr ratios, and silicate sediments often have higher δ26Mg and 87Sr/86Sr ratios than runoff at the study site. Mixing of these two sources, if confirmed, could reconcile the flux and isotope data.

Accumulation and within-mushroom distribution of elements in red cracking bolete (Xerocomellus chrysenteron) collected over the extended period from compositionally contrasting substrates.

We conducted a study of elemental compositions of Xerocomellus chrysenteron samples accompanied by samples of related substrate soils. All samples were collected during the harvesting seasons 2021 and 2022 from three forested sites almost unpolluted by recent human activities and underlain by contrasting bedrock (granite, amphibolite, and serpentinite). Elements such as Ag, Cd, K, P, Rb, S, Se, and Zn were the main elements enriched in the mushroom's fruiting bodies relative to the substrate. Concentrations of most elements in mushrooms were not site-dependent, with only Ag, As, Rb, and Se concentrations significantly depending on the bedrock composition. Some elements analyzed in mushrooms displayed temporal features, but such features were not systematic and varied for each element. Most analyzed elements were distributed unevenly within the mushroom's fruiting bodies, with apical parts generally enriched in mobile elements. Mushrooms influenced concentrations of Ag, Cd, K, and Rb and a few other elements in the substrate via uptake, but such influence was very limited and can be responsible for only 2.5-11.5% of total depletion of the affected substrate in the named elements.

Spatial and temporal trends in δ66Zn and 206Pb/207Pb isotope ratios along a rural transect downwind from the Upper Silesian industrial area: Role of legacy vs. present-day pollution.

Transect sampling is an under-exploited tool in isotope studies of atmospheric pollution. Few studies have combined Zn and Pb isotope ratios to investigate whether atmospheric pollution at a receptor site is dominated by a different anthropogenic source of each of these toxic elements. It has been also unclear whether pollution abatement strategies in Central Europe have already resulted in regionally well-mixed background isotope signature of atmospheric Zn and Pb. Zinc and lead isotope ratios were determined in snow collected along a rural transect downwind from the Upper Silesian industrial area (southern Poland). Spatial and temporal gradients in δ66Zn and 206Pb/207Pb ratios at four sites were compared with those of ore and coal collected in eight Czech and Polish mining districts situated at distances of up to 500 km. Snow pollution was extremely high 8 km from Olkusz in 2011 (1670 µg Zn L-1; 240 µg Pb L-1), sharply decreased between 2011 and 2018, and remained low in 2019-2021. Snow pollution was lower at sites situated 28-68 km from Olkusz. Across study sites, mean δ66Zn and 206Pb/207Pb ratios of snow were -0.13‰ and 1.155, respectively. With an increasing distance from Olkusz, the δ66Zn values first increased and then decreased, while the 206Pb/207Pb ratios first decreased and then increased. The δ66Zn values in snow plotted closer to those of Upper Silesian ores (-0.20‰) than to the δ66Zn values of Upper Silesian stone coal (0.52‰), showing predominance of smelter-derived over power-plant derived Zn pollution. The 206Pb/207Pb ratios of Upper Silesian coal (1.171) and Upper Silesian ores (1.180) were higher compared to those of snow. A206Pb/207Pb vs.208Pb/207Pb plot identified legacy pollution from leaded gasoline as the low-radiogenic mixing end-member. Across the transect sites, only the last sampling campaign exhibited a high degree of isotope homogenization for both Zn and Pb.

Translocation of elements and fractionation of Mg, Cu, Zn, and Cd stable isotopes in a penny bun mushroom (Boletus edulis) from western Czech Republic.

Boletus edulis mushroom behaved as an accumulating biosystem with respect to Ag, Rb, Zn, and K. The mushroom was not an efficient accumulator of toxic As, Pb, and Cr, but Se and Cd displayed much higher concentrations in the mushroom than in the substrate samples. Other elements were bioexclusive. Different elements had different within-mushroom mobilities. The highest mobilities were displayed by Zn and Ag, and the lowest by Ti. The mushroom's fruiting body preferentially took up lighter Mg, Cu, and Cd isotopes (Δ26MgFB-soil = -0.75‰; Δ65CuFB-soil = -0.96‰; Δ114CdFB-soil = -0.63‰), and the heavier 66Zn isotope (Δ66ZnFB-soil = 0.92‰). Positive within-mushroom Zn isotope fractionation resulted in accumulation of the heavier 66Zn (Δ66Zncap-stipe = 0.12‰) in the mushroom's upper parts. Cadmium displayed virtually no within-mushroom isotope fractionation. Different parts of the fruiting body fractionated Mg and Cu isotopes differently. The middle part of the stipe (3-6 cm) was strongly depleted in the heavier 26 Mg with respect to the 0-3 cm (Δ26Mgstipe(3-6)-stipe(0-3) = -0.73‰) and 6-9 cm (Δ26Mgstipe(6-9)-stipe(3-6) = 0.28‰) sections. The same stipe part was strongly enriched in the heavier 65Cu with respect to the 0-3 cm (Δ65Custipe(3-6)-stipe(0-3) = 0.63‰) and 6-9 cm (Δ65Custipe(6-9)-stipe(3-6) = -0.42‰) sections. An overall tendency for the upper mushroom's parts to accumulate heavier isotopes was noted for Mg (Δ26Mgcap-stipe = 0.20‰), Zn (Δ66Zncap-stipe = 0.12‰), and Cd (Δ114Cdcap-stipe = 0.04‰), whereas Cu showed the opposite trend (Δ65Cucap-stipe = -0.08‰).

First data on isotope and trace element compositions of a Xerocomus subtomentosus mushroom sample from western Czech Republic.

A study of a sample of Xerocomus subtomentosus revealed that the fruiting body behaved as an accumulating biosystem with respect to Rb (BF = 36), K and Ag (BF = 5.0 for both), and, to a lesser extent, Mg, Cu, Zn, and Se (BF = 1.7-3.1). A Xerocomus mushroom has not shown to be a good accumulator of toxic As (BF = 0.64), Cd (BF = 0.65), and Pb and Cr (BF < 0.1 for both) from the soil. Within-mushroom distribution of the trace elements showed very high mobility of Ag (TF = 54) and As (TF = 16); moderate mobility of K, Ti, Pb, and Rb (TF = 2.1-3.1); and low mobility to immobility of other elements. A mushroom preferentially intakes isotopically heavy Mg (Δ26Mgstipe-soil = 0.22‰) and Zn (Δ66Znstipe-soil = 0.68‰), and isotopically light Cu (Δ65Custipe-soil = - 1.04‰). The fruiting body has shown insignificant but measurable within-mushroom isotope fractionation with the higher parts of the fruiting body accumulating isotopically lighter Cu (Δ65Cucap-stipe = - 0.06‰), Zn (Δ66Zncap-stipe = - 0.18‰), and Mg (Δ26Mgcap-stipe = - 0.31‰). Such a behavior is overall similar to that displayed by the higher plants.

Catchment Runoff in Industrial Areas Exports Legacy Pollutant Zinc from the Topsoil Rather than Geogenic Zn.

In highly industrialized, densely populated parts of Central Europe, mobilization of legacy Zn pollution from forest ecosystems may negatively affect the quality of water resources. To test this hypothesis, we determined the 66Zn/64Zn isotope ratios of 15 Zn reservoirs and fluxes in an acidified, spruce die-back affected mountain-slope catchment in northern Czech Republic. The δ66Zn values of precipitation, organic horizon, and runoff were statistically indistinguishable. In contrast, δ66Zn values of bedrock orthogneiss and mineral soil were significantly different from δ66Zn values of runoff. The magnitude of within-site Zn isotope fractionations appeared to be relatively small. Despite the large potential source of Zn in bedrock, runoff exported mostly young pollutant Zn that had been temporarily stored in the organic horizon. This conclusion was corroborated by comparing Zn input-output mass balances in the polluted northern catchment and in a relatively unpolluted catchment situated 250 km to the south. Seven-times higher Zn export via runoff at the northern site was controlled by a combination of 10-times higher atmospheric Zn input and five-times higher DOC leaching, compared to the southern site. In industrial areas, atmospherically deposited Zn is leached from headwater catchments in a direct analogy to leaching of highly toxic pollutant Pb.

Controls on δ26Mg variability in three Central European headwater catchments characterized by contrasting bedrock chemistry and contrasting inputs of atmospheric pollutants.

Magnesium isotope ratios (26Mg/24Mg) can provide insights into the origin of Mg pools and fluxes in catchments where Mg sources have distinct isotope compositions, and the direction and magnitude of Mg isotope fractionations are known. Variability in Mg isotope compositions was investigated in three small, spruce-forested catchments in the Czech Republic (Central Europe) situated along an industrial pollution gradient. The following combinations of catchment characteristics were selected for the study: low-Mg bedrock + low Mg deposition (site LYS, underlain by leucogranite); high-Mg bedrock + low Mg deposition (site PLB, underlain by serpentinite), and low-Mg bedrock + high Mg deposition (site UDL, underlain by orthogneiss). UDL, affected by spruce die-back due to acid rain, was the only investigated site where dolomite was applied to mitigate forest decline. The δ26Mg values of 10 catchment compartments were determined on pooled subsamples. At LYS, a wide range of δ26Mg values was observed across the compartments, from -3.38 ‰ (bedrock) to -2.88 ‰ (soil), -1.48% (open-area precipitation), -1.34 ‰ (throughfall), -1.19 ‰ (soil water), -0.99 ‰ (xylem), -0.95 ‰ (needles), -0.82 ‰ (bark), -0.76 ‰ (fine roots), and -0.76 ‰ (runoff). The δ26Mg values at UDL spanned 1.32 ‰ and were thus less variable, compared to LYS. Magnesium at PLB was isotopically relatively homogeneous. The δ26Mg systematics was consistent with geogenic control of runoff Mg at PLB. Mainly atmospheric/biological control of runoff Mg was indicated at UDL, and possibly also at LYS. Our sites did not exhibit the combination of low-δ26Mg runoff and high-δ26Mg weathering products (secondary clay minerals) reported from several previously studied sites. Six years after the end of liming at UDL, Mg derived from dolomite was isotopically undetectable in runoff.

The variations of aluminium species in mountainous forest soils and its implications to soil acidification.

Aluminium (Al) speciation is a characteristic that can be used as a tool for describing the soil acidification process. The question that was answered is how tree species (beech vs spruce) and type of soil horizon affect Al speciation. Our hypotesis is that spruce and beech forest vegetation are able to modify the chemical characteristics of organic horizon, hence the content of Al species. Moreover, these characteristics are seasonally dependent. To answer these questions, a detailed chromatographic speciation of Al in forest soils under contrasting tree species was performed. The Jizera Mountains area (Czech Republic) was chosen as a representative mountainous soil ecosystem. A basic forestry survey was performed on the investigated area. Soil and precipitation samples (throughfall, stemflow) were collected under both beech and spruce stands at monthly intervals from April to November during the years 2008-2011. Total aluminium content and Al speciation, pH, and dissolved organic carbon were determined in aqueous soil extracts and in precipitation samples. We found that the most important factors affecting the chemistry of soils, hence content of the Al species, are soil horizons and vegetation cover. pH strongly affects the amount of Al species under both forests. Fermentation (F) and humified (H) organic horizons contain a higher content of water extractable Al and Al(3+) compared to organo-mineral (A) and mineral horizons (B). With increasing soil profile depth, the amount of water extractable Al, Al(3+) and moisture decreases. The prevailing water-extractable species of Al in all studied soils and profiles under both spruce and beech forests were organically bound monovalent Al species. Distinct seasonal variations in organic and mineral soil horizons were found under both spruce and beech forests. Maximum concentrations of water-extractable Al and Al(3+) were determined in the summer, and the lowest in spring.

The pH-dependent long-term stability of an amorphous manganese oxide in smelter-polluted soils: implication for chemical stabilization of metals and metalloids.

An amorphous manganese oxide (AMO) and a Pb smelter-polluted agricultural soil amended with the AMO and incubated for 2 and 6 months were subjected to a pH-static leaching procedure (pH 3-8) to verify the chemical stabilization effect on metals and metalloids. The AMO stability in pure water was pH-dependent with the highest Mn release at pH 3 (47% dissolved) and the lowest at pH 8 (0.14% dissolved). Secondary rhodochrosite (MnCO3) was formed at the AMO surfaces at pH>5. The AMO dissolved significantly less after 6 months of incubation. Sequential extraction analysis indicated that "labile" fraction of As, Pb and Sb in soil significantly decreased after AMO amendment. The pH-static experiments indicated that no effect on leaching was observed for Cd and Zn after AMO treatments, whereas the leaching of As, Cu, Pb and Sb decreased down to 20%, 35%, 7% and 11% of the control, respectively. The remediation efficiency was more pronounced under acidic conditions and the time of incubation generally led to increased retention of the targeted contaminants. The AMO was found to be a promising agent for the chemical stabilization of polluted soils.

Release of mobile forms of hazardous elements from glassworks fly ash into soils.

The release of hazardous elements from the wastes of high-temperature processes represents a risk to the environment. We focused on the alteration of fly ash (FA) from glassworks collected from an electrostatic filter. FA contains elevated concentrations of Zn and Ba, among other elements. Overtime, small amounts of FA have been emitted from the factory and settled into the surrounding environment (soil). In order to assess the possible risks to the environment, samples of FA were placed in small nylon bags and deposited in 11 different soil horizons (containing diverse vegetation cover such as spruce and beech and also unforested areas). Samples of the FA in bags were exposed in the soils for 1 year. Then, the bags were collected, and the exposed soils in the direct vicinity of the FA bags were sampled. The total concentrations of Zn and Ba in the FA, as well as in the soil samples (original and exposed), were determined by ICP MS. The "mobile fraction" was determined as the exchangeable (acid extractable) fraction of the modified BCR sequential extraction procedure (SEP). The SEP results indicate that Zn and Ba may pose a potential environmental risk. Their concentrations in the first, most mobile, and bioavailable fraction increased in all the exposed soils. The most significant increases were observed in the upper soil horizons (litter and A horizon). The risk to the environment was evaluated on the basis of the Risk Assessment Code.

Dust from Zambian smelters: mineralogy and contaminant bioaccessibility.

Metal smelting is often responsible for local contamination of environmental compartments. Dust materials escaping from the smelting facilities not only settle in the soil, but can also have direct effects on populations living close to these operations (by ingestion or inhalation). In this particular study, we investigate dusts from Cu-Co metal smelters in the Zambian Copperbelt, using a combination of mineralogical techniques (XRD, SEM/EDS, and TEM/EDS), in order to understand the solid speciation of the contaminants, as well as their bioaccessibility using in vitro tests in simulated gastric and lung fluids to assess the exposure risk for humans. The leaching of metals was mainly dependent on the contaminant mineralogy. Based on our results, a potential risk can be recognized, particularly from ingestion of the dust, with bioaccessible fractions ranging from 21 to 89% of the total contaminant concentrations. In contrast, relatively low bioaccessible fractions were observed for simulated lung fluid extracts, with values ranging from 0.01% (Pb) up to 16.5% (Co) of total contaminant concentrations. Daily intakes via oral exposure, calculated for an adult (70 kg, ingestion rate 50 mg dust per day), slightly exceeded the tolerable daily intake limits for Co (1.66× for fly ash and 1.19× for slag dust) and occasionally also for Pb (1.49×, fly ash) and As (1.64×, electrostatic precipitator dust). Cobalt has been suggested as the most important pollutant, and the direct pathways of the population's exposures to dust particles in the industrial parts of the Zambian Copperbelt should be further studied in interdisciplinary investigations.

Surprisingly contrasting metal distribution and fractionation patterns in copper smelter-affected tropical soils in forested and grassland areas (Mufulira, Zambian Copperbelt).

Six soil profiles located near Mufulira (Zambian Copperbelt) were studied to evaluate and compare the extent of environmental pollution of Cu-ore mining and smelting in both forested and grassland areas. The highest metal concentrations were detected in the uppermost soil layers with the following maxima: Co 45.8 mg kg(-1), Cu 8,980 mg kg(-1), Pb 41.6 mg kg(-1), and Zn 97.0 mg kg(-1). Numerous anthropogenic metal-bearing particles were detected in the most polluted soil layers. The spherical smelter-derived particles were mainly composed of covellite (CuS) and chalcocite (Cu2S), while the angular mining-derived particles were mostly composed of chalcopyrite (CuFeS2). Additionally, Fe-Cu oxide particles predominantly corresponding to tenorite (CuO) and delafossite (Cu(1+)Fe(3+)O2), along with hydrated Fe-oxides corresponding to secondary weathering products, were detected. In contrast to smelter-affected soils in temperate climates, where forest soils are significantly more enriched in metals than tilled soils due to high canopy interception, our data indicate a higher proportion of metal-bearing anthropogenic particles and higher metal concentrations in soils from unforested sites. This phenomenon is probably related to the more frequent and intense bushfires in forested areas, leading to the mobilization of pollutants contained in the biomass-rich surface soils back into the atmosphere.

Temporal dissolution of potentially toxic elements from silver smelting slag by synthetic environmental solutions.

Waste slag which is created during precious metal smelting contains high levels of potentially toxic elements (PTE) which can be mobilised from unconfined deposits into the local environment. This paper examines the extractability of selected PTE (Pb, Zn, Cd, Mn) from slag samples by synthetic solutions designed to replicate those in the environment. Extracting agents were used to replicate potential leaching scenarios which are analogous to natural chemical weathering. Slag was submersed in a rainwater simulation solution (RSS), weak citric acid solution (representing rhizosphere secretions) and control solutions (deionised water) for a one month period with solution analyses made at intervals of 1, 24, 168 and 720 h. In 1 mM citric acid, dissolution of Cd and Zn showed little change with time, although for Zn the initial dissolution was considerable. Lead in citric acid was characterized by overall poor extractability. Mn solubility increased until an equilibrium state occurred within 24 h. The solubility of studied metals in citric acid can be characterized by a short time to equilibrium. RSS proved to be an effective solvent that, unlike citric acid solution, extracted increasing concentrations of Cd, Mn and Zn with time. Solubility of Pb in RSS was again very low. When taken as a proportion of a single 2 M HNO3 extraction which was applied to slag samples, Cd was the element most readily leached into RSS and control samples. In both studied solvents, slag heterogeneity is prominent in the case of Cd and Zn solubility. Contact time with solvent appears to be an important variable for the release of PTE from slag into solution. The purpose of this study was to provide insight into the environmental chemical dissolution of PTE from slag, which causes their enrichment in surrounding soils and surface waters.

Profile distribution and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests.

The behaviour of principal inorganic anions in forest soils, originating mainly from acid deposition, strongly influences the forest ecosystem response on acidification. The aim of this study was to describe seasonal and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests in a region heavily impacted by acidification. The Jizera Mountains area (Czech Republic) was chosen as such a representative mountainous soil ecosystem. Soil samples were collected at monthly intervals from April to October during the years 2008-2010 under both beech and spruce stands. Soil samples were collected from surface fermentation (F) and humified (H) organic horizons, humic (A) organo-mineral horizons and subsurface mineral (B) horizons (cambic or spodic). A deionised water extract was applied to unsieved fresh samples and the content of anions in these extracts was determined by ion chromatography (IC). In the studied soil profiles, the lowest amount of SO(4)(2-) was found in the organo-mineral A horizons under both types of vegetation. Under spruce the highest amount of SO(4)(2-) was determined in mineral spodic (B) horizons, where a strong sorption influence of Fe and Al oxy-hydroxides is expected. Under beech the highest amount was observed in the surface organic F horizons (forest floor). The amount of NO(3)(-) is highest in the F horizons and decreases with increasing soil profile depth under both types of vegetation. A significantly higher amount of NO(3)(-) was determined in soils under the beech stand compared to spruce. For both soil environments - under beech and also spruce stands - we have determined a general increase of water-extractable SO(4)(2-) and NO(3)(-) during the whole monitoring period. The behaviour of SO(4)(2-) and NO(3)(-) in the soils is strongly related to the dynamics of soil organic matter and particularly to the DOC.

Experimental in situ transformation of Pb smelter fly ash in acidic soils.

Soils in the vicinity of nonferrous metal smelters are often highly polluted by inorganic contaminants released from particulate emissions. We used a technique with double polyamide experimental bags (1-µm mesh) to study the in situ transformation of fly ash (FA) from a secondary Pb smelter in acidic soil profiles. Between 62 and 66% of the FA dissolved after one year's exposure in the soils, leading to complete dissolution of primary caracolite (Na(3)Pb(2)(SO(4))(3)Cl) and KPb(2)Cl(5), with formation of secondary anglesite (PbSO(4)), minor PbSO(3), and trace carbonates. Release of Pb was pH-dependent, whereas not for Cd and Zn. Significant amounts of metals (mainly Cd and Zn) partitioned into labile soil fractions. The field data agreed with laboratory pH-static leaching tests performed on FA, which was washed before the experiment to remove soluble salts. This indicates that appropriate laboratory leaching can accurately predict FA behavior in real-life scenarios (e.g., exposure in soil).

Natural attenuation of arsenic in soils near a highly contaminated historical mine waste dump.

Arsenic-contaminated soils near historical As-rich mine waste in Jáchymov (Czech Rep.), resulting from the smelting and seepage of the mine waste pore water, were studied to examine As partitioning between solid phases and pore waters. Mineralogical and geochemical analyses showed that As is exclusively associated with unidentified amorphous Fe oxyhydroxides, poorly crystalline goethite and hematite as adsorbed and coprecipitated species (with up to 3.2 wt.% As). Adsorption of As by Fe oxyhydroxides is likely to be a major control on the migration of As in the soil pore water containing only up to 15 µg L(-1) As(V). The slight variations in the dissolved As(V) concentrations do not follow the total contents of As in the soil or adsorbed As, but appeared to be a function of pH-dependent sorption onto Fe oxyhydroxides. The geochemical modelling using PHREEQC-2 supported the efficiency of As(V) adsorption by Fe oxyhydroxides in the soil affected by As-rich waste solution seepage. It also suggested that active Fe oxyhydroxides has a strong attenuation capacity in soil that could effectively trap the aqueous As(V) from the unremitting waste seepage for the next approx. 11600 years.

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.

Effect of sample preparation on contaminant leaching from copper smelting slag.

Currently standardised leaching tests require grain size reduction, which for large fragments of slags could overestimate the leaching results. To assess the effect of the fine-grained fraction generated by sample crushing, a set of leaching experiments was performed on copper smelting slag from the Zambian Copperbelt: (i) EN 12457-2 batch tests (standardised grain size <4 mm; modified procedure with grain size of 4-0.5 mm simulating exposure of larger fragments on the dumps) and (ii) CEN/TS 14997 pH-static tests (standardised grain size <1 mm simulating the possible wind dispersion scenario near the slag crushing facilities or disposal of fine-grained granulated slag; additional grain sizes <5 mm, 5-0.5 mm and 5-0.5 mm after ultrasonic cleaning). A higher proportion of the fine-grained fraction generally led to greater leaching of Cu, Co and Zn. The metal levels in the leachates under circum-neutral conditions were all below the EU limits for non-hazardous waste. However, at pH 4, the presence of fine dust particles dramatically increased the concentrations of metals in the slag leachates. The greater leachability of Cu and Co from slag particles under acidic conditions suggests a risk of their mobilisation in acidic soils in the Copperbelt area.

Effect of illite and birnessite on thallium retention and bioavailability in contaminated soils.

The influence of illite and birnessite (δ-MnO(2)) amendments on the retention and bioavailability of Tl in contaminated soils was investigated. The efficiency of both phases was evaluated using Tl uptake by white mustard (Sinapis alba L.), sequential extraction and sorption experiments. The obtained data demonstrate that the application of birnessite can effectively transform Tl from the labile (easily mobilizable) fraction to its reducible form, thus lowering Tl bioavailability in soil and subsequent accumulation by plants. The Mn oxide added to the soils reduced substantially Tl uptake; Tl levels in the plants decreased by up to 50%, compared to the non-amended soil. The effect of illite on the immobilization and uptake of Tl was less pronounced, and in the carbonate-rich Leptosol has not been proved at all, suggesting the importance of bulk soil mineralogy and nature of the soil sorption complex on the behavior of this amendment. Therefore, the general applicability of illite for Tl stabilization in soils seems to be limited and strongly dependent on soil composition. In contrast, the use of birnessite like soil additive might be an efficient and environment-friendly solution for soil systems contaminated with Tl.

Association of trace elements with colloidal fractions in leachates from closed and active municipal solid waste landfills.

Leachates from two Czech municipal solid waste (MSW) landfills (closed site and active site) were size-fractionated using the cascade frontal filtration/ultrafiltration procedure with filter cut-offs of 3 µm, 0.8 µm, 0.45 µm, 0.1 µm, 10 kDa and 1 kDa. To evaluate the binding of trace elements to colloidal particles, the filtrates were analyzed for major compounds (FAAS, ICP-OES and HPLC) and trace elements (ICP-MS) and the obtained elemental patterns were statistically evaluated. Transmission electron microscopy (TEM) indicated that the colloids were mostly inorganic, mainly composed of carbonates and clays. Characteristic features of the behaviour of trace elements and the main compounds were more pronounced at the active landfill site. Amongst the main compounds, only Fe and Ca decrease significantly and have similar patterns to numerous trace elements, indicating their capture by colloidal particles (at least 25%). Arsenic, Se and Rb exhibit zero or negligible decrease in concentration in the leachate during the filtration procedure. This fact indicates their particularly high mobility, which should be considered in preventing the flux of harmful compounds from landfill systems.