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.

Long-Term Vegetation Changes and Socioeconomic Effects of River Engineering in Industrialized Areas (Southern Poland).

The exploitation of mineral resources associated with human mining activities leads to the degradation of both terrestrial and aquatic biocenotic systems. The drastic disturbance of water relations as a result of the relocation of the riverbed of the Biala Przemsza River (southern Poland) for coal and filler sand mining will lead to changes in plant ecosystems. The purpose of this study was to determine and compare the diversity and distribution of vegetation in the Biala Przemsza valley in sections of channel straightening with the old riverbed and areas undisturbed by engineering works against the background of land use in temporal and spatial aspects. The results of the ecological and phytosociological studies showed that the composition of flora and vegetation types varied. Within the transformed riverbed, anthropogenic mixed forests with species characteristic of different ecological systems are developing, whereas the non-regulated section of the river is overgrown by an alder riparian forest with an almost complete species composition for this plant community. The highest Simpson's biodiversity index was found in the anthropogenically disturbed section of the river (0.86), and in the undisturbed section, it was 0.83. Both sections of the river were dominated by species of the family Compositae, Poaceae, Caryophyllaceae, Rosaceae and Apiaceae. The diversity of the flora in the transformed sections of the valley is determined by the presence of mosaics and microhabitats, as well as the nature of the surrounding vegetation, which is reflected in the ecological requirements of the flora concerning light preference (moderate light [56.25%]), and almost 90% of the flora from the area of the regulated section of the valley develops on humus-poor and mineral-humus soils. Although this area has lost its original natural function, it is now valuable for selected economic and social functions, especially in highly urbanized regions.

High concentrations of HgS, MeHg and toxic gas emissions in thermally affected waste dumps from hard coal mining in Poland.

This study aims to provide numerous environmental research approaches to understand the formation of mineral and organic mercury compounds in self-heating coal waste dumps of the Upper Silesian Coal Basin (USCB). The results are combined with environmental and health risk assessments. The mineralogy comprised accessory minerals in the fine fraction of thermally affected waste, i.e., Hg sulfides, most likely cinnabar or metacinnabar. Moreover, other metals, e.g., Pb, Zn and Cu, were found as sulfide forms. Apart from Hg, the ICP-ES/MS data confirmed the high content of Mn, Zn, Pb, Hg, Cr and Ba in these wastes. The high concentration of available Hg resulted in elevated MeHg concentrations in the dumps. There were no correlations or trends between MeHg concentrations and elemental Hg, TS, TOC, and pH. Furthermore, we did not detect microbial genes responsible for Hg methylation. The organic compounds identified in waste and emitted gases, such as organic acids, or free methyl radicals, common in such burn environments, could be responsible for the formation of MeHg. The concentration levels of gases, e.g., benzene, formaldehyde, NH3, emitted by the vents, reached or surpassed acceptable levels numerous times. The potential ecological and human health risks of these dumps were moderate to very high due to the significant influence of the high Hg concentrations.

Evaluation of thallium isotopic fractionation during the metallurgical processing of sulfides: An update.

In this study, we report combined Tl isotopic and Tl mineralogical and speciation data from a set of Tl-rich sulfide concentrates and technological wastes from hydrometallurgical Zn extraction. We also present the first evaluation of Tl isotopic ratios over a cycle of sulfide processing, from the ore flotation to pyro- and hydrometallurgical stages. The results demonstrate that the prevailing Tl form in all samples is Tl(I), without any preferential incorporation into sulfides or Tl-containing secondary phases, indicating an absence of Tl redox reactions. Although the Tl concentrations varied significantly in the studied samples (~9-280 mg/kg), the overall Tl isotopic variability was small, in the range of -3.1 to -4.4 ± 0.7 (2σ) ε205Tl units. By combining present ε205Tl results with the trends first found for a local roasting plant, it is possible to infer minimum Tl isotopic effects throughout the studied industrial process. As a result, the use of Tl isotopic ratios as a source proxy may be complicated or even impossible in areas with naturally high/extreme Tl background contents. On the other hand, areas with two or more isotopically contrasting Tl sources allow for relatively easy tracing, i.e., in compartments which do not suffer from post-depositional isotopic redistributions.

Vegetation and Environmental Changes on Contaminated Soil Formed on Waste from an Historic Zn-Pb Ore-Washing Plant.

Post-mining waste from Zn-Pb ore exploitation undergoes processes of spontaneous succession and changes in soil chemical composition. The Zakawie area was industrially transformed by historical mining activity, ore enrichment, and the metallurgical processing of Zn-Pb ore. The subject of the study was to analyse the rate of vegetation succession (from 1999 to 2019), soil chemistry, and the relationships between them in an anthropogenic habitat with high concentrations of potentially toxic metals. Ecological and geochemical studies were carried out in an area contaminated with waste from a disused Zn-Pb ore-washing plant. Between 1999 and 2019, the transformation of grassland and meadow vegetation into scrub and forest-grassland communities was observed. This transformation led to a decrease in the area of Molinietum caeruleae meadow (from 25.8% in 1999 to 10.7% in 2019), whose place was taken by Prunus spinosa and Rhamnus cathartica. The community of xerothermic limestone grasslands completely disappeared, being replaced in favour of the Diantho-Armerietum and Prunus spinosa community. In this period, the share of lifeforms of plants and species composition (46 and 60, respectively) also changed. The Shannon and Simpson biodiversity index reached high values in the second investigation period, and it was 0.893 and 0.86, respectively. The anthrosols had a high content of Zn-85,360 mg kg-1, Pb-28,300 mg kg-1, Cd-340 mg kg-1, and As-1200 mg kg-1. Carbonates, clay minerals, and fe-oxides are predominant in the mineral composition of the rhizosphere; the metal-bearing phases are stable; and hardly soluble minerals include smithsonite, cerussite, monheimite, hemimorphite, and oxides of Fe and Fe-Mn. Mineralisation/crust processes formed on the epidermis, and their influences on root development were found. Scanning electron microscopy and energy-dispersive X-ray spectroscopy studies on rhizosphere soil components provide information on the type of minerals and their susceptibility to heavy metals release. The identification of some biotic and mineral structures in rhizospheres can be an interesting source of information on pedogenic processes identified in back-scattered electron images.

Heavy metal- and organic-matter pollution due to self-heating coal-waste dumps in the Upper Silesian Coal Basin (Poland).

This study provides potential insight between self-heating coal-waste dumps and related environmental pollution in southern Poland. Samples collected from dumps in the Upper Silesian Coal Basin were used to quantify released contents of organic- and inorganic pollutants, i.e., polycyclic aromatic hydrocarbons (PAHs) and trace elements (Pb, Cd, Cr, Cu, Zn, Ni, Hg, As). Elevated Hg concentrations (~100-1078 mg/kg) and Pb (~600-2000 mg/kg) attest to the evaporation of these metals from deeper parts of the dumps. The acidic pH levels (3.0-4.5) may help to mobilize these elements. Pearson's correlation coefficients for samples analyzed by AAS and ICP-MS indicate a similar origin for Cd, Zn, and As. Mostly 2- and 3-ring PAHs, especially anthracene in burnt soil, dominate in the samples. Chlorinated PAHs, thiophenol, pyridines, quinolines (and derivatives) in thermally-altered samples, and waste containing pyrolytic bitumen indicate coking conditions. The high levels of Hg, Pb, and Cd, and chlorinated PAHs and nitrogen heterocycles formed or enriched during self-heating in these dumps should be deemed a significant environmental hazard. Calculating the lifetime cancer risks due to PAHs and heavy metals accumulations in the dumps are substantial, and access to these dumps should be prohibited.

Integrated geophysical and geochemical methods applied for recognition of acid waste drainage (AWD) from Zn-Pb post-flotation tailing pile (Olkusz, southern Poland).

Long-term underground exploitation of Zn-Pb ores has led to drainage of the area and formation of a huge dumping ground in the form of a pile. In its vicinity, processes of acid drainage have developed as a result of contamination of soils and groundwater. Geochemical transformations of mineral contents of waste can significantly affect physical and chemical properties of the soils and the bedrock. At the prospect of termination of the mining activity in the near future, determining the routes of the pollution migration, ability to monitor acid drainage processes and assessment of the risk of heavy metal pollution are really crucial. The paper presents a proposal for solving this problem by means of geophysical methods: Electrical Resistivity Tomography (ERT), Time Domain-Induced Polarisation (TDIP), Frequency Domain Electromagnetics (FDEM) and shallow-depth magnetometric surveys combined with geochemical investigations. The obtained results of geophysical surveys have been confirmed by geochemical investigations. The applied ERT and TDIP methods make it possible to identify the spread of the zones of pollution around the tailing pile, but their effectiveness depends on humidity of the ground. Soil magnetometry and shallow-depth induction profiling are a good tool to identify the medium contaminated with minerals redeposited by aeolian processes and allow to determine the range of the dust spread from the pile. It has been shown that the range of impact of the geochemical changes around the tailing pile is high and depends not only on directions and dynamics of water flow from the pile but also on aeolian transport.

Thallium isotopes in metallurgical wastes/contaminated soils: A novel tool to trace metal source and behavior.

Thallium (Tl) concentration and isotope data have been recorded for contaminated soils and a set of industrial wastes that were produced within different stages of Zn ore mining and metallurgical processing of Zn-rich materials. Despite large differences in Tl levels of the waste materials (1-500mgkg-1), generally small changes in ε205Tl values have been observed. However, isotopically lighter Tl was recorded in fly ash (ε205Tl∼-4.1) than in slag (ε205Tl∼-3.3), implying partial isotope fractionation during material processing. Thallium isotope compositions in the studied soils reflected the Tl contamination (ε205Tl∼-3.8), despite the fact that the major pollution period ended more than 30 years ago. Therefore, we assume that former industrial Tl inputs into soils, if significant, can potentially be traced using the isotope tracing method. We also suggest that the isotope redistributions occurred in some soil (subsurface) horizons, with Tl being isotopically heavier than the pollution source, due to specific sorption and/or precipitation processes, which complicates the discrimination of primary Tl. Thallium isotope analysis proved to be a promising tool to aid our understanding of Tl behavior within the smelting process, as well as its post-depositional dynamics in the environmental systems (soils).

Isotopic Tracing of Thallium Contamination in Soils Affected by Emissions from Coal-Fired Power Plants.

Here, for the first time, we report the thallium (Tl) isotope record in moderately contaminated soils with contrasting land management (forest and meadow soils), which have been affected by emissions from coal-fired power plants. Our findings clearly demonstrate that Tl of anthropogenic (high-temperature) origin with light isotope composition was deposited onto the studied soils, where heavier Tl (ε(205)Tl ∼ -1) naturally occurs. The results show a positive linear relationship (R(2) = 0.71) between 1/Tl and the isotope record, as determined for all the soils and bedrocks, also indicative of binary Tl mixing between two dominant reservoirs. We also identified significant Tl isotope variations within the products from coal combustion and thermo-desorption experiments with local Tl-rich coal pyrite. Bottom ash exhibited the heaviest Tl isotope composition (ε(205)Tl ∼ 0), followed by fly ash (ε(205)Tl between -2.5 and -2.8) and volatile Tl fractions (ε(205)Tl between -6.2 and -10.3), suggesting partial Tl isotope fractionations. Despite the evident role of soil processes in the isotope redistributions, we demonstrate that Tl contamination can be traced in soils and propose that the isotope data represent a possible tool to aid our understanding of postdepositional Tl dynamics in surface environments for the future.

Geochemical position of Pb, Zn and Cd in soils near the Olkusz mine/smelter, South Poland: effects of land use, type of contamination and distance from pollution source.

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.