Uncovering the sources of soil lead in the Old Copper Basin (SW Poland): insights from Pb isotope geochemistry

In the present work the extent and variation of Zn, Cd, Pb, Cu, and Hg loading in undisturbed surface soil (0–5 cm) and the vertical transport of the metals in soil profiles are studied in the vicinity of a zinc smelter in Norway. Three major controlling factors on the metal concentrations in soil have been assessed: 1) distance from the anthropogenic point source; 2) organic matter content (O.M.); and 3) the prevailing wind directions. Moreover metal distributions in proximal soil profiles in 1972 and 2003 are compared. Current concentrations of Zn, Cd, Pb, Cu, and Hg in surface soil reach 14000, 60, 980, 430, and 7.0 mg·kg − 1 , respectively, near the smelter and decrease regularly with distance in the northerly direction according to the regression model (y = ax− b ). The Zn concentrations are significantly different from the background range up to 30 km from the smelter, whereas the other metals approach background at only 10 km distance. Subsurface concentration peaks of Pb, Cu, and Hg are found at greater depth in soil profiles than peaks of Zn and Cd. Levels of Zn, Cd, and Pb in surface soil seem to have decreased from 1972 to 2003, whereas for Cu the levels appear not to be significantly different.

Hydrogen sulphide (H2S) occurs in groundwater in various lithostratigraphic units of the Zechstein Basin in the Legnica-Głogów Copper Basin (SW Poland). This region is located in the Fore-Sudetic Monocline within which, several tens of kilometres NE of the study area, at greater depths, natural gas fields with hydrogen sulphide (H2S) occur. The Main Dolomite (Ca2), in which H2S-containing natural gas has accumulated, is younger than the Zechstein Limestone (Ca1), which is actively mined. The Ca2 and Ca1 formations are separated by a thick anhydrite succession including a wedge-shaped salt body. Hydrochemical analyses of 18 groundwater samples taken from different horizons within the Zechstein strata showed spatial variability ofH2S and chloride concentrations. A conceptual model of groundwater flow with dissolved H2S in the Zechstein formations was developed. H2S migration is associated with groundwater flow between the Ca2 and Ca1 aquifers through fissures in the anhydrite strata that separate them. Hydraulic contact through fissures in the anhydrite layers is the result of long-term exploitation of the underground copper deposit. Groundwater flow between the layers is influenced by a large change in the piezometric pressure of the groundwater in the depression cone caused by mining drainage.

Copper isotope ratios differ between hypogene sulfidic, supergene sulfidic and oxidized ore sources. Traditional lead isotope signatures of ancient metals are specific to deposits, while Cu isotope signatures are specific to the types of ore minerals used for metal production in ancient times. Two methodological case studies are presented: First, the mining district of Faynan (Jordan) was investigated. Here, mainly oxidized copper ores occur in the deposits. The production of copper from Fayan’s ore sources is confirmed by the measurement of the Cu isotope signature of ingots from the Early Bronze Age metal workshop from Khirbat Hamra Ifdan. Based on our results illustrating differences in the Cu isotope composition between the ore mineralizations from Timna (Israel) and Faynan, it is now possible to determine these prehistoric mining districts from which copper artifacts originated by combining trace elements and Pb isotopes with Cu isotopes. The second case study presents data on Late Bronze Age copper production in Cyprus. Oxhide ingots from the shipwreck of Uluburun (Turkey) were tested for their lead isotope signatures and assigned to Cypriot deposits in the recent decades. The oxhide ingots from Uluburun show a Cu isotope signature which we also found for oxidized copper ores from Cyprus, while younger oxhide ingots as well as metallurgical slag from the Cypriot settlements Kition and Enkomi show a different signature which might be due to the use of sulfidic ore sources from a greater depth of deposits. We assert that there could be a chronological shift from oxidized to sulfidic ore sources for the copper production in Cyprus, requiring different technologies. Therefore, Cu isotopes can be used as a proxy to reconstruct mining and induced smelting activities in ancient times.

Source apportionment of Pb in a rice-soil system using field monitoring and isotope composition analysis

Combined approach for assessing metal(loid)s leaching, mobility and accumulation in a specific near-neutral (pH) environment of a former Cu-smelting area in the Old Copper Basin, Poland

National-scale distribution of strontium isotope ratios in environmental samples from South Korea and its implications for provenance studies

Lead isotopic signatures in Antarctic marine sediment cores: A comparison between 1 M HCl partial extraction and HF total digestion pre-treatments for discerning anthropogenic inputs

Anthropogenic Radioisotopes in the Topsoil of Qatar: Is it Something to Worry About?

Lead concentrations and isotopic compositions in the Western Philippine Sea

At the fortified settlement of the Bronze Age, Ustye-I (South Trans-Urals), metal products of copper, arsenic and tin bronzes, numerous fragments of metallurgical slags, as well as fragments of copper ores have been discovered. According to the results of early studies, pure copper predominates among metal items (53.4% of finds), but also a significant part contains an admixture of arsenic (25.4% of finds), tin (13.6% of finds) and both components simultaneously (7.6% of finds). Several alloying components of the samples are simultaneously found in slags: Pb (50% of cases), As (49% of cases), Zn (40% of cases), Bi (38% of cases), Sn (7% of cases), Ni (4% of cases), Sb (1% of cases). To identify the relationship between the incoming raw materials and the received metal, 15 ore samples were examined. The ores studied are ‘gravelly’ clasts with a size of 5 mm to several centimeters, and ‘sandy’ ores with a size of 2–3 mm. According to their mineral composition, ores are subdivided into malachite, azurite, and limonite. The main copper minerals are malachite and azurite; chrysocolla is found occasionally, chalcopyrite, cuprite are rarely found. Copper is bound to Fe- and Mn-hydroxides. We have identified copper slag fragments in ‘sandy’ ores. In all types of ores, natural alloying components are very rare and are represented by Pb and Zn. These elements can form their own minerals (mottramit, a mineral of the plumbogummite family) or act as an impurity to malachite (up to 0.62 wt% ZnO), azurite (up to 1.12 ZnO and up to 2.37 PbO), iron hydroxides (up to 2.66 ZnO and up to 2.02 PbO) or manganese hydroxides (up to 0.41 ZnO and up to 9.48 PbO). No As and Sn impurities were found. The presence of numerous fragments of brown iron ore at the settlement, the close location of copper mines indicates that the settlers were engaged in the extraction and processing of copper ore. The widespread occurrence of ores, consisting mainly of malachite and azurite, indicates that the ores were mined from the upper parts of the oxidation zone, and the metal smelted from these ores must correspond to pure copper. The distribution of Pb and Zn impurities indicates that some of the copper ores originate from the oxidation zones of pyrite ores or deposits of other formational types with a similar ore composition. The difference in the compositions of the ores found at the settlement and the compositions of slag and metal is associated with several sources of ores. The sources of copper ores could be mines located near the settlement. Arsenic-bearing ores could have come from mines in adjacent areas. Tin ores were brought in as a result of trans-regional exchange with the Central Asian region.

In this study, we report lead isotopic compositions from oxidized Cu ores, host rocks, metal smelting residues, and soils from the Zechstein Ca1 formation which is associated with the Kupferschiefer copper deposits. The lithology is dominated by marls and slates, where Cu mineralization appears in carbonates, mostly malachite. Historical smelting left numerous slag remnants around the site (Derkowska et al. 2023). The Pb isotope ratios in ores and slags are highly diverse in comparison to previous studies of Cu ores and smelting products in Poland (Tyszka et al. 2012), i.e. 206Pb/207Pb ratio ranges from 1.094 to 2.092 for ores and from 1.151 to 1.240 for slags. This diversity is likely related to the oxidized character of the ore, which contains less Pb compared to sulfide-dominated ores and, in consequence, its Pb isotopic composition is dominated by radiogenic Pb produced by U-rich host rocks. This translates to significant differences in Pb isotope records between oxidized and reduced (sulfide) deposits that can be utilized in environmental and provenance studies. Similar diversity in soil samples is consistent with contamination by such ores and/or slags. Analyzed soils show highly variable 206Pb/207Pb ratios in lower soil horizons, whereas Pb isotope ratios in topsoils are similar to those typical for a whole region of Lower Silesia in Poland (1.17-1.19). This suggests the dominance of modern atmospheric Pb in the surface environment which we link to Polish and Czech coal combustion and name as the Lower Silesian Contemporary Pollution Signal.Our study shows that using oxidized Cu-ores may introduce high diversity in Pb isotopic composition to smelting products, wastes, and consequently the environment. This affects both environmental and provenance studies as only a restricted isotope ratio can be attributed to a single source. On the other hand, high diversity in 206Pb/207Pb ratios in slag samples may also indicate the addition of oxidized Cu ores during smelting thus may be also an asset to identify when oxidized ores were used or acted as a pollution source.Acknowledgments: The study is funded by the National Science Centre grant to KD (2019/35/N/ST10/04524)Derkowska K., Kierczak J., Potysz A., Pietranik A., Pędziwiatr A., Ettler V., Mihaljevič M., 2023, Combined approach for assessing metal(loid)s mobility and accumulation in a near-neutral (pH) environment of a former Cu-smelting area in the Old Copper Basin, Poland: when nature is the ‘bad guy’. Applied Geochemistry, 105670. https://doi.org/10.1016/j.apgeochem.2023.105670Tyszka R., Pietranik A., Kierczak J., Ettler V., Mihaljevič M., Weber J., 2012, Anthropogenic and lithogenic sources of lead in Lower Silesia (Southwest Poland): an isotopic study of soils, basement rocks and anthropogenic materials. Applied Geochemistry, 27, 1089-1100, http://dx.doi.org/10.1016/j.apgeochem.2012.02.034

While the history, techniques of exploitation and deposit parameters of the copper ores in the North-Sudetic Synclinorium have been the subject of numerous investigations, the transformations of the terrain in the so-called “Old Copper Basin” (Lower Silesia, SW Poland) have not been analysed in detail before. This paper is intended to complement this gap. The authors present the results of the detailed geomorphometric analysis of the post-mining forms related directly to the copper mining. The LiDAR-based, high-resolution Digital Terrain Models (DTMs), which have been used in the analysis and description of the landforms, are currently considered as the most accurate and precise 3D-spatial data available in the numerical form. The following anthropogenic forms are distinguished in the study area: large- and small-scale ground deformations (depressions and small sinkholes), abandoned quarries, and forms associated with the exploitation and storage of the flotation wastes – post-flotation tailings and dumps. Our investigations have allowed visualization of the spatial distribution of the forms, estimation of their total volume as well as perspectives of their reclamation and protection.

This study evaluated the potential of the diffusive gradients in thin films (DGT) technique to assess radiogenic strontium (Sr) and lead (Pb) isotope signatures in bioavailable soil fractions as a proxy for plant uptake. Concentrations (cDGT) and isotope ratios of Sr (87Sr/86Sr) and Pb (207Pb/206Pb, 208Pb/206Pb, 206Pb/204Pb) assessed by DGT (TK100, Chelex), along with extractable (NH4NO3, NH4OAc, EDTA) and total Sr and Pb mass fractions and isotope ratios, were compared to those in Lactuca sativa L. (lettuce), Triticum aestivum L. (wheat), and Raphanus sativus L. (radish) grown on five geochemically distinct soils. Relative to conventional soil extraction, DGT significantly reduced matrix loads, facilitating isotope ratio measurements by multi-collector inductively coupled plasma mass spectrometry. DGT-labile Sr and Pb concentrations and isotope ratios reflected soil-specific geochemical signatures, allowing for clear differentiation among soils. Importantly, DGT-labile isotope ratios closely matched those in plant tissues across soils and species within analytical uncertainty, demonstrating that DGT captures the isotopically relevant bioavailable Sr and Pbpool without inducing significant mass-dependent isotopic fractionation. These findings establish DGT as a practical tool for bioavailable multi-isotope tracing with strong potential for applications in environmental forensics, food authentication, and archaeological provenance research.

Strontium isotope composition as a tracer of calcium sources in two forest ecosystems in Belgium

A multi-media monitoring field investigation, which included atmospheric, road sediment and soil samples, was carried out at two highway study sites to identify past and present Pb sources. Past Pb anthropogenic sources such as paint and leaded gasoline were linked to significant Pb accumulation in roadside soils at both sites through Pb isotopic analyses. This was achieved by identifying the distinct Pb isotopic composition in older versus newer Pb accumulation at different depths across the soil profile. Older Pb accumulations exhibited lower 206Pb/207Pb isotopic ratios, consistent with Canadian Pb-bearing ores, whereas newer Pb accumulations reflected a mixture of the 206Pb/207Pb ratios of road sediment samples, with the Pb isotopic signature of uncontaminated soil. Isotopic analyses were also helpful in identifying road sediment as an important current source of Pb in roadside soils, by comparing the isotopic signatures derived from road sediment and atmospheric dustfall. The known association of Pb with anthropogenic sources was used to indirectly relate other metals (Cu, Mn, Zn) to the same source by the Enrichment Ratio method. Significant positive correlations at the 90–95% confidence level were found between Cu, Zn and Pb Enrichment Ratios in roadside and dust deposition samples. Weaker correlations were found between Mn and Pb, at the highway study site with the least amount of traffic. However, correlations between these two metals were significant at the 90% confidence level for the busier highway site highlighting Mn potential anthropogenic source. An isotopic tracer study is suggested to further investigate the process of Mn redistribution in the environment due to exhaust fuel emissions. More research is needed regarding the potential impact from using a Mn-based fuel additive.