Using elemental concentrations and dust loadings as metrics of human exposure to potentially toxic elements in kindergarten indoor dust

Due to the hand-to-mouth activities frequently observed among the youngest children, they are likely to ingest higher amounts of indoor dust than adults. Since pre-schoolers are prone to exposure to potentially toxic elements (PTEs) through the ingestion route, characterising human exposure within kindergarten microenvironments is paramount for children who spend considerable time in school. Ergo, a study encompassing five kindergartens in an industrial city was performed. Indoor dust samples were collected from the kindergartens. The present study reports dust metal concentrations and metal loadings to estimate indoor exposure to PTEs. Total concentrations of chromium (Cr), cobalt (Co), nickel (Ni), cadmium (Cd), arsenic (As) and lead (Pb) were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in the of the <63 μm and <250 μm particle size fractions of the indoor dust. The results show that the elemental loadings vary widely among the different kindergartens but are consistently higher in the finer dust size fraction. Non-parametric analysis (Spearman's rank-order correlation) shows strong and significant (p<0.001) positive correlations between total dust loading - dust elemental loading. Relatively strong correlations were also obtained between elemental loadings and elemental concentrations, but the relationship is only significant for Ni and Pb. The strong correlation (rs= 0.73) between Pb concentration and dust Pb loading suggests that total dust loading has a greater influence on dust Pb loading. The results suggest a negligible influence of dust mass over the dust elemental loading for elements such as Cd, Co, Cr and As

Mercury deposition/accumulation rates in the vicinity of a lead smelter as recorded by a peat deposit

. Recent findings show that Hg records from peat tend to overestimate historical levels of Hg deposition. Therefore we used the mass loss compensation factor (MLCF) to normalize Hg accumulation rates. These corrected Hg accumulation rates were significantly lower (maximum 129 mg m À2 yr À1 ) and better corresponded to changes in historical smelter emissions, which were highest in the 1960s. The agreement between the corrected Hg accumulation rates in the uppermost peat sections (2-38 mg m À2 yr À1 ) and biomonitoring of atmospheric deposition by mosses in several recent years (4.7-34.4 mg m À2 yr À1 ) shows the usefulness of MLCF application on Hg accumulation in peat archives. However, the MLCF correction was unsuitable for Pb. The recent Pb deposition rates obtained by an independent biomonitoring study using mosses (0.5-127 mg m À2 yr À1 ) were better correlated with net Pb accumulation rates recorded in peat (7-145 mg m À2 yr À1 ) than with corrected rates obtained by the MLCF approach (1-28 mg m À2 yr À1 )

Thallium and lead variations in a contaminated peatland : a combined isotopic study from a mining/smelting area

Vertical profiles of Tl, Pb and Zn concentrations and Tl and Pb isotopic ratios in a contaminated peatland/fen (Wolbrom, Poland) were studied to address questions regarding (i) potential long-term immobility of Tl in a peat profile, and (ii) a possible link in Tl isotopic signatures between a Tl source and a peat sample. Both prerequisites are required for using peatlands as archives of atmospheric Tl deposition and Tl isotopic ratios as a source proxy. We demonstrate that Tl is an immobile element in peat with a conservative pattern synonymous to that of Pb, and in contrast to Zn. However, the peat Tl record was more affected by geogenic source(s), as inferred from the calculated element enrichments. The finding further implies that Tl was largely absent from the pre-industrial emissions (>~250 years BP). The measured variations in Tl isotopic ratios in respective peat samples suggest a consistency with anthropogenic Tl (ε205Tl between ~ -3 and 4), as well as with background Tl isotopic values in the study area (ε205Tl between ~0 and 1), in line with detected 206Pb/207Pb ratios (1.16–1.19). Therefore, we propose that peatlands can be used for monitoring trends in Tl deposition and that Tl isotopic ratios can serve to distinguish source origin(s). However, given that the studied fen has a particularly complicated geochemistry (attributed to significant environmental changes in its history), it seems that ombrotrophic peatland(s) could be better suited for this type of Tl research

Thallium in Technosols from Allchar (North Macedonia): Isotopic and speciation insights

Allchar (North Macedonia) mining area is known for anomalous background Tl concentrations. In this study, we combine accurate detection of Tl stable isotope ratios with data on mineralogy/speciation and chemical extraction of Tl in Tl-contaminated Technosol profiles. We demonstrate that Tl in the studied soils varies significantly in both concentration (500 mg/kg-18 g/kg) and isotopic composition (− 1.6 and +3.2 of ε205Tl, a ~0.5‰ spread), which is due to changes in the phase chemistry and/or mineralogy of Tl. Moreover, the observed 205Tl/203Tl ratios do not reflect the extent to which individual soils undergo Tl isotopic fractionation during mineral weathering and soil formation. Clearly, they reflect the initial isotopic signal(s) of the primary ore or ore minerals, and thus, the general history or type of their genesis. As the Tl carriers, various types of Tl–Me-arsenates, mixtures of jarosite and dorallcharite and minor Mn-oxides predominated. We revealed intense adsorption of Tl by the identified Mn-oxides (≤6.7 at.%). It is hypothesized that these phases are of key importance in the fractionation of Tl isotopes, meaning at this type of secondary oxide-soil solution interface. However, model studies involving primary/secondary components (sulfides, sulfates, oxides and arsenates) are required to understand the mechanisms that may lead to post-depositional Tl isotopic redistribution in soils, as well as Tl isotope systematics in mining wastes in general

Circulation Patterns of Copper-Based Alloys in the Late Iron Age Oppidum of Třísov in Central Europe

This article presents an insight into the sourcing and circulation of copper alloys during the Late La Tène period in Central Europe&nbsp; where the specialised production of metals is regarded as complex and conducted chiefly within the bounds of the oppida. Contrary to the logical, though not necessarily data-based, assumption that local raw materials for the production of bronze were mostly used from the local primary deposits, we argue that an advanced and complex economy of Late Iron Age allowed for the steady and consistent material supply even from distant areas and that such pattern was possibly commonly practised by the oppida sites.&nbsp; Concurrently, we do not argue against the possibility of the exploitation and processing of the locally mined metal, we only point out that in provenance studies the evidence for that is yet difficult to find. We back our hypothesis by archaeometric analysis of the&nbsp; assemblage of bronze objects from the oppidum of Třísov (Czech Republic) collected during the long-term investigations of this site. The selection of objects for analyses covers the spectrum from the local products to potentially imported items. A provenancestudy based on the analysis of lead isotopes and chemical composition has shown rather homogeneous pattern of lead isotopic values and, on the contrary, quite a variability among the chemical composition of the individual artefact groups suggesting thus 1)&nbsp; standardised technological procedures for individual types of objects, 2) common recycling of the materials used and/or 3)&nbsp; contamination of low-leaded alloys from highly leaded bronzes

Effect of accelerated weathering and leaching on the chemistry and phytotoxicity of coal-mine overburden

Overburden weathering may influence its effects on soil development and plant growth. Here, an accelerated-weathering experiment was used to determine how weathering affects the chemistry and toxicity of coal-mine overburden. Seven samples of overburden were collected; two samples were from a heap of partly weathered material, and five from mining pits. In both cases, the most weathered top 10 cm was removed. Samples included coal-rich clays (with > 1% coal) and coal-free clays. The samples were artificially weathered by subjecting them to 20 cycles of drying-rewetting-freezing-thawing. Coal-rich clays that have not been weathered were acidic and toxic to Sinapis alba seedlings, but weathering increased their pH, reduced their conductivity and tended to reduce their phytotoxicity. In contrast, weathering tended to reduce the pH of coal-free alkaline clays. S. alba grew poorly in weathered coal-free clay, but when grown in coal-rich clays it grew better in some substrates whereas others were phytotoxic due to their high As content. Weathering decreased Al, As and Na contents and decreased substrate mass by 1–37%. Overall, these results indicate that weathering changes the properties of overburden in ways that are important for soil development and plant growth but the nature and extent of the changes depend on the initial composition of the substrate

Termite dispersal is influenced by their diet.

peer reviewedTermites feed on vegetal matter at various stages of decomposition. Lineages of wood- and soil-feeding termites are distributed across terrestrial ecosystems located between 45°N and 45°S of latitude, a distribution they acquired through many transoceanic dispersal events. While wood-feeding termites often live in the wood on which they feed and are efficient at dispersing across oceans by rafting, soil-feeders are believed to be poor dispersers. Therefore, their distribution across multiple continents requires an explanation. Here, we reconstructed the historical biogeography and the ancestral diet of termites using mitochondrial genomes and δ13C and δ15N stable isotope measurements obtained from 324 termite samples collected in five biogeographic realms. Our biogeographic models showed that wood-feeders are better at dispersing across oceans than soil-feeders, further corroborated by the presence of wood-feeders on remote islands devoid of soil-feeders. However, our ancestral range reconstructions identified 33 dispersal events among biogeographic realms, 18 of which were performed by soil-feeders. Therefore, despite their lower dispersal ability, soil-feeders performed several transoceanic dispersals that shaped the distribution of modern termites

Oral bioaccessibility of inorganic contaminants in waste dusts generated by laterite Ni ore smelting

International audienc

Chemostratigraphic correlation of sediments containing expandable clay minerals based on ion exchange with cu(II) triethylenetetramine

Copper(II) triethylenetetramine [Cu(trien)] is an agent suitable for the 1-step determination of the cation exchange capacity (CEC) of many geomaterials using a procedure much less laborious than other, commonly used methods. It is also suitable for the determination of the composition of original exchangeable cations. In contrast to other common ions used for CEC analysis, the Cu(II) complex with triethylenetetramine, [Cu(trien)], is specific for expandable clay minerals. The robustness of [Cu(trien)] analysis was verified using reference clays, ion-exchanged reference clays, sediments, and soils. The [Cu(trien)]-based CEC of expandable clay minerals is not influenced significantly by ferrihydrite, goethite, manganite, birnessite, calcite, and gypsum. Birnessite, calcite, and gypsum admixtures affect the composition of the evolved cations. [Cu(trien)] does not recover the entire CEC of soils (but rather that of the clay minerals only) which contain components other than clays which contribute to the CEC, e.g. soil organic matter. In a series of loess with buried paleosols and recent soils the [Cu(trien)]-based CEC ranged from 30 to 110% of total CEC obtained by traditional BaCl methods. The relative ratio of Ca to Mg, the prevailing exchangeable cations in soils and sediments in exogenic environments, are similar after [Cu(trien)] and conventional BaCl treatments. The Ca/Mg ratio in the exchangeable fraction was used successfully for chemostratigraphic correlation of paleolacustrine sediments from a large lake in the Upper Carboniferous basins of eastern equatorial Pangaea and a series of recent flood plain sediments of the meandering Morava River in the Czech Republic. The Ca/Mg ratio obtained by [Cu(trien)] analysis is proposed as a novel tool for the chemostratigraphic correlation of sediment series containing expandable clay minerals

Mineralogy of Air-Pollution-Control Residues from a Secondary Lead Smelter: Environmental Implications

International audienceThe mineralogy and solubility of air-pollution-control (APC) residues from a secondary lead (Pb) smelter have been studied on samples from the Příbram smelter, Czech Republic, recycling car batteries, with the emphasis on their potential environmental effect. The presence of dominant anglesite (PbSO4) and laurionite (Pb(OH)Cl) was observed in a sintered residue from after-burning chambers (800−1000 °C). In contrast, low-temperature Pb-bearing phases, such as KCl·2PbCl2 and caracolite (Na3Pb2(SO4)3Cl), were detected in the major APC residue from bag-type fabric filters. Metallic elements, zinc (Zn), cadmium (Cd), and tin (Sn) were found homogeneously distributed within this residue. The formation of anglesite, cotunnite (PbCl2), (Zn,Cd)2SnO4, and (Sb,As)2O3 was observed during the sintering of this APC residue at 500 °C in a rotary furnace. The 168 h leaching test on filter residue, representing the fraction that may escape the flue gas treatment system, indicated rapid release of Pb and other contaminants. Caracolite and KCl·2PbCl2 are significantly dissolved, and anglesite and cotunnite form the alteration products, as was confirmed by mineralogical analysis and PHREEQC-2 modeling. The observed Pb-bearing chlorides have significantly higher solubility than anglesite and, following emission from the smelter stack, can readily dissolve, transferring Pb into the environmental milieu (soils, water, inhabited areas)