Martin Mihaljevič | Charles University, Prague (original) (raw)

Papers by Martin Mihaljevič

Journal of Geochemical Exploration, 2022

Chemosphere, 2020

Slag dusts from Kabwe (Zambia) contain high levels of contaminants. Metals bound in slag glass, c... more Slag dusts from Kabwe (Zambia) contain high levels of contaminants. Metals bound in slag glass, carbonates, oxides and phosphates/ vanadates. Bioaccessible fractions up to 96% (Pb), 100% (V) and 81% (Zn). High health risk even under conservative dust intake scenario (100 mg/ day).

Journal of African Earth Sciences, 2021

Applied Geochemistry, 2019

Abstract The historical mining and processing of Zn–Pb–V ores at Berg Aukas in northern Namibia l... more Abstract The historical mining and processing of Zn–Pb–V ores at Berg Aukas in northern Namibia left large amounts of various wastes. This study focuses on the mineralogical and geochemical investigation of the V-rich slags issued from the processing of the local ores in the Waelz kiln, which was operational between 1968 and 1980 and left ca. 500 kt of slag deposited on the adjacent dump. A combination of mineralogical methods, bulk chemistry, leaching tests and speciation-solubility modeling was used to understand the binding of the major contaminants (Zn, Pb, V) in the solid phase and their potential release under the changing environmental conditions. The average concentrations of the metal(loid) contaminants in the slags are 3.78 wt% Zn, 3370 mg/kg Pb, 5880 mg/kg V, 767 mg/kg Cu, 578 mg/kg As and 92 mg/kg Sb. The mineralogy is dominated by high-temperature silicates (clinopyroxene, melilite, olivine-family phases) and Zn-bearing phases (willemite, zincite). All the primary silicates and oxides are Zn-rich, but vanadium is mainly concentrated in clinopyroxene (up to 5 wt% V2O3). Metallic Fe inclusions, formed under highly reducing conditions in the kiln, are highly weathered. Secondary Fe(III) (hydr)oxides, corresponding to the main weathering products in the slag, efficiently sequester the metal(loid)s (mainly As and Sb). The EU regulatory leaching tests indicated that the release of the metal(loid) contaminants is quite low at the natural pH (deionized water extract: 8.5–10.4) obtained by extraction in the deionized water and only Sb in all the slag samples exceeds the EU limits for the landfilling of inert waste. The pH-static leaching tests revealed up to 5 orders of magnitude higher release of Pb and Zn under acidic conditions (up to 38% and 63% of their total concentration, respectively), compared to the natural pH. In contrast, V exhibits relatively flat pH-dependent leaching patterns with only

Environmental Science and Pollution Research, 2018

The impact of a natural wetland ("dambo" in Zambia) on neutral mine drainage at Luanshya in the Z... more The impact of a natural wetland ("dambo" in Zambia) on neutral mine drainage at Luanshya in the Zambian Copperbelt has been investigated during an intermediate discharge period (July) using a multi-method characterization of solid phase samples, sequential extraction analysis, X-ray diffraction, Mössbauer spectroscopy, and scanning electron microscopy combined with water analyses, isotopic analyses, and geochemical modeling. In the wetland, the principal identified solid phases in sediments were carbonates, gypsum, and ferric oxyhydroxides. A significant portion of the ochres was present as insoluble hematite. Mine drainage pH values decrease, and log P CO 2 values increase after inflow of water into the wetland; dissolved and suspended concentrations of Fe, Mn, Cu, and Co also decrease. Based on speciation calculations, there is no precipitation of secondary Cu and Co minerals in the period of sampling, but it can occur later in dry period when the flow rate is reduced. Concentrations of sulfate decrease, and values of δ 34 S(SO 4) in the wetland increase in parallel, suggesting sulfate reduction is occurring. In more advanced dry period, the discharge in mine drainage stream is probably much lower and water can reach supersaturation with respect to minerals such as gypsum, which has been found in sediments. Wetlands have a positive impact on mine drainage water quality due to the removal of metals by adsorption, co-precipitation, and filtration of colloids. However, there can also be a rebound of contamination by seepage inflow downstream from the wetland. Ongoing climate change with extreme hydrologic events may enhance differences between dry and rainy seasons with resulting faster mobilization of contaminants.

Environment International, 2019

Ore mining and processing in semi-arid areas is responsible for the generation of metal(loid)-con... more Ore mining and processing in semi-arid areas is responsible for the generation of metal(loid)-containing dust, which is easily transported by wind to the surrounding environment. To assess the human exposure to dustderived metal(loid)s (As, Cd, Cu, Pb, Sb, Zn), as well as the potential risks related to incidental dust ingestion, we studied mine tailing dust (n = 8), slag dust (n = 5) and smelter dust (n = 4) from old mining and smelting sites in northern Namibia (Kombat, Berg Aukas, Tsumeb). In vitro bioaccessibility testing using extraction in simulated gastric fluid (SGF) was combined with determination of grain-size distributions, chemical and mineralogical characterizations and leaching tests conducted on original dust samples and separated PM 10 fractions. The bulk and bioaccessible concentrations of the metal(loid)s were ranked as follows: mine tailing dusts < slag dusts ≪ smelter dusts. Extremely high As and Pb bioaccessibilities in the smelter dusts were caused by the presence of highly soluble phases such as arsenolite (As 2 O 3) and various metal-arsenates unstable under the acidic conditions of SGF. The exposure estimates calculated for an adult person of 70 kg at a dust ingestion rate of 50 mg/day indicated that As, Pb (and also Cd to a lesser extent) grossly exceeded tolerable daily intake limits for these contaminants in the case of slag and smelter dusts. The high risk for smelter dusts has been acknowledged, and the safety measures currently adopted by the smelter operator in Tsumeb are necessary to reduce the staff's exposure to contaminated dust. The exposure risk for the local population is only important at the unfenced disposal sites at Berg Aukas, where the PM 10 exhibited high levels of bioaccessible Pb. especially high in arid or semi-arid areas, where the total respirable aerosols (PM 10 ; i.e., particulate matter of grain sizes equal to 10 μm or less) significantly exceed permissible levels as defined by environmental agencies and health organizations (US EPA, WHO) (Ghorbel et al., 2010; Csavina et al., 2012; Thomas et al., 2018). For example, Ojelede et al. (2012) reported that the PM 10 concentration was > 2000 μg/m 3 at higher wind speeds in the vicinity of a mine tailing site in South Africa; this value far exceeds the 24-h limit value of 150 μg/m 3 stipulated by US EPA. Apart from the consumption of contaminated water and food, the incidental ingestion and/or inhalation of dust and soil particles

Journal of Geochemical Exploration, 2018

Kabwe Town and its surroundings (central Zambia) belong to the most contaminated districts in Afr... more Kabwe Town and its surroundings (central Zambia) belong to the most contaminated districts in Africa due to mining and smelting of local Pb-Zn ores. To assess the extent and intensity of this anthropogenic contamination, samples of topsoil (from a depth of 0 to 3 cm), together with reference subsurface soil from a depth of 70-90 cm, were collected in the area. In the Kitwe Town and downwind, the Pb and Zn contents in topsoils were found to be significantly higher compared to the permissible ecological limits used in Canada with regard to various land uses. Other elements (Cu, Fe, Mn, Cr, Ni and Ba) in topsoil demarcate only a small area of the former ore processing and smelter grounds.

Environmental pollution (Barking, Essex : 1987), 2018

We studied arid desert soils from Namibia (Rosh Pinah) that were contaminated with up to 7 mg kg ... more We studied arid desert soils from Namibia (Rosh Pinah) that were contaminated with up to 7 mg kg of thallium (Tl) via dust emitted from a local flotation tailing dam. Chemical extractions of waste and soil materials indicated that most of the Tl is strongly bound, in accordance with X-ray diffraction and X-ray absorption spectroscopy data that point to the predominant association of Tl with metal sulfides and phyllosilicates. The isotope fractionation factor εTl of the soil samples (from -0.4 to +3.8) shows a positive linear relationship (R = 0.62) with 1/Tl, indicative for the mixing of two major Tl pools, presumably anthropogenic Tl and geogenic Tl. The εTl value for the topmost soil samples (∼+3) closely matches the εTl value for post-flotation waste particles with a diameter of <0.05 mm, whereas the bulk flotation waste exhibits a significantly larger εTl value (∼+6). These variations are in accordance with predominant atmospheric transfer of Tl from the tailings to the adjac...

Geoderma, 2017

We studied Fe-Mn concentric nodules from Cutanic Luvisol in the northern part of Namibia, where a... more We studied Fe-Mn concentric nodules from Cutanic Luvisol in the northern part of Namibia, where agricultural fields are irrigated with the drainage water from the Kombat Cu-Pb-(Zn) mine (pH 7, metal concentrations in μg l −1 : Fe 7, Mn 10, Zn 7, Cu 18). Concentric nodules (0.5-2 cm in size) were mostly found towards the bottom of the sampled soil profile (Btcg2 horizon, depth 100-120 cm). Comparisons with the bulk chemical composition of the soil matrix showed that Fe-Mn nodules were enriched in metals, metalloids and other trace elements (with a few exceptions, enrichment factors varied in the range 1.3-6.4). The concentrations of the elements of interest in the Fe-Mn nodules were as follows (mg kg −1): As 23.1, Ba 3840, Cd 6.83, Cu 450, Pb 597, Zn 137. The X-ray diffraction analysis indicated that the nodules were composed of quartz, goethite, hematite, illite/mica, pyrochroite, lithiophorite and birnessite. The scanning electron microscopy (SEM) observations confirmed that the internal structure of the nodules with concentric rings reflected seasonal changes in the redox conditions. Spot analyses and X-ray elemental maps performed using energy/wavelength dispersion spectrometry (EDS/ WDS) showed that the concentrations of metalloids were rather low except for the slightly elevated Ba concentrations, which were observed only within the Mn oxide-rich zones. Selective extractions were used to understand the partitioning of trace elements within the individual phases. Whereas Mn oxides sequestered the majority of the Cd (up to 98%), Ba, Pb and rare earth elements (REEs) (up to 78%), other metals such as Cu and Zn exhibited much lower values (47-65%) and, together with oxyanionic species (As, Cr, V), were also significantly bound to Fe oxides. The pH-static leaching test conducted in the pH range 2-12 indicated that the majority of the trace elements were mostly leached under acidic conditions with the exception of As, which was highly solubilized at pH 12 (up to 17%). Whereas Ba, Cd, Cu and Zn were significantly released under acidic conditions (up to 12%), the leaching of Pb was almost negligible over the entire pH range. Our results show that Fe-Mn nodules act as significant traps for trace metals in Luvisols irrigated by mine water. However, an abrupt decrease in the pH and changes in the redox conditions may cause the dissolution of Fe-Mn nodules and subsequent release of contaminants into the soil system.

Journal of Hazardous Materials, 2018

h i g h l i g h t s • Thallium isotopes in industrial wastes from zinc metallurgy. • Thallium con... more h i g h l i g h t s • Thallium isotopes in industrial wastes from zinc metallurgy. • Thallium contamination in soils can be traced using isotopes. • Thallium isotope fractionation may occur in soil. • Sorption and/or precipitation processes are responsible for isotope redistribution.

Environmental science & technology, Sep 20, 2016

Here, for the first time, we report the thallium (Tl) isotope record in moderately contaminated s... more 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), su...

Science of The Total Environment, 2016

Mining-and smelter-derived particles identified in subtropical and semi-arid soils • Sulphides, o... more Mining-and smelter-derived particles identified in subtropical and semi-arid soils • Sulphides, oxides, and metal-bearing arsenates most frequently encountered • Soluble sulphates and arsenolite from primary smelter dusts not detected in soils • Higher metal availability and greater weathering of particles in subtropical soils • Complex Ca-Cu-Pb arsenates efficiently control mobility of metal(loids).

Science of The Total Environment, 2015

More than 250 year-old arsenopyriterich mine waste dump was studied. • Mineral transformation and... more More than 250 year-old arsenopyriterich mine waste dump was studied. • Mineral transformation and the environmental stability of different secondary arsenic mineral phases were assessed. • High efficiency of As sequestration by HFOs suggests a limited impact of the mine waste dump on the surrounding soils.

Water, Air, & Soil Pollution, 2015

The contents of As, Cu, Cd, Pb, Mn, along with the Pb isotopic ratios 206 Pb/ 207 Pb and 208 Pb/ ... more The contents of As, Cu, Cd, Pb, Mn, along with the Pb isotopic ratios 206 Pb/ 207 Pb and 208 Pb/ 206 Pb were studied in both soils and tree rings of the marula tree (Sclerocarya birrea) in the vicinity of the Tsumeb deposit (Namibia). Amounts of all the studied metals and As are higher in the immediate vicinity of the Tsumeb Cu-Pb smelter in the soil. The tree rings also have their maximum content of all the studied substances in the vicinity of the smelter (with the exception of Pb). At a more distant site, the maximum concentration of Pb in the soils was 29.8 mg/kg, while the content in the soil in the vicinity of the smelter was as much as 8,174 mg/kg. In the vicinity of the smelter, the maximum Pb content in the tree rings reaches a value of 5.7 mg/kg, compared to a more distant site, where the contents are as high as 9.2 mg/kg. The lower Pb content in the trees on contaminated soil indicates that the composition of the xylem determines the above-ground uptake, rather than the root uptake. Similarly, the above-ground uptake is documented by the isotopic composition of Pb at the distant location, where the tree rings have different contents of Pb isotopes compared to in the soil. The As, Cd, Cu, Pb, and Zn contents are highest in the tree rings from the 1950s (and older), along with those from the 1990s, while the Mn contents were highest in those from the 1960s and 1990s. The contaminant peaks in the 1950s and 1960s could be associated with the roasting of sulfidic ores, while the peak values in the 1990s could have been caused by the start of Cu slag reprocessing in the late 1980s, and culmination of works at the smelter prior to the closing of the mine. The tree rings of the marula tree were found to be a suitable archive for above-ground pollution close to Cu and Pb smelters.

Journal of African Earth Sciences, 2015

Mine tailings at Rosh Pinah located in semiarid southern Namibia were investigated by the combina... more Mine tailings at Rosh Pinah located in semiarid southern Namibia were investigated by the combination of mineralogical methods and leaching using water and simulated gastric solution. They are well-neutralized with leachate pH > 7 and neutralization potential ratios (NPR) up to 4. Neutralization is mainly due to abundant Mn-rich dolomite in the matrix. Concentrations of released contaminants in water leachate follow the order Zn > Pb > Cu > As. Relatively high leached concentrations of Zn and partly also of Pb are caused by their link to relatively soluble carbonates and Mn-oxyhydroxides. In contrast, As is almost immobile by binding into Fe-oxyhydroxides, which are resistant to dissolution. Barium is released by the dissolution of Ba-carbonate (norsethite} and precipitates in sulphate-rich pore water as barite. Dissolved concentrations in neutral mine drainage water collected in the southern pond are low, but when total concentrations including colloidal fraction are taken into account, more than 70 % of Zn is in colloidal form. Groundwater upgradient of the mine tailings is of poor quality and there seems to be no negative impact on groundwater downgradient from mine tailings. Contaminant concentrations in simulated gastric leachates are in the order Ba > Pb > Zn > Cu > As with a maximum gastric bioaccessibility of 86.6.0 % for Ba and a minimum of 3.3 % for As. These results demonstrate that total contaminant content and toxicity in the solid phase are poor predictors of risk, and therefore mineralogical and bioavailability/bioaccessibility studies are necessary for evaluation of contaminant environmental impact.

Journal of Soils and Sediments, 2014

PurposeWhereas mercury (Hg) has been extensively studied in gold mining areas (including artisana... more PurposeWhereas mercury (Hg) has been extensively studied in gold mining areas (including artisanal mining), it is often overlooked as a minor contaminant in these districts, within which industrial base-metal mining and smelting are in operation. The aims of this study were to investigate Hg in tropical soils from mining and smelting areas in Namibia and Zambia and to apply statistical methods to generate models for the prediction of Hg concentrations in the soils studied.Materials and methodsTwenty-one soil profiles (n = 159 soil samples) were collected in metal mining districts in the northern parts of Namibia (Tsumeb, Berg Aukas, Kombat) and in the Zambian Copperbelt (Kitwe, Mufulira). Total Hg was analysed by atomic absorption spectrometry and compared statistically with other physico-chemical and chemical soil parameters. Mercury concentrations in potential sources (feed and wastes from smelters as well as mine tailings, n = 35) were also determined.Results and discussionMercury concentrations in soils from mining/smelting areas were significantly higher in northern Namibia (range 0.0038–4.39, mean 0.39, median 0.02 mg kg−1) than in the Zambian Copperbelt (range 0.0055–0.39, mean 0.02, median 0.01 mg kg−1). This phenomenon is related to the higher levels of Hg in the mine tailing materials as well as the feed/wastes from the smelters in Namibia (specifically in Berg Aukas and Tsumeb). Only 27 % (Namibia) and 26 % (Zambia) of the soil samples exceeded geochemical anomaly thresholds (0.033 and 0.016 mg kg−1, respectively), generally indicating a low Hg pollution level. The highest Hg concentrations were observed in the uppermost soil layers. Total Hg correlated significantly with other contaminants and, in the Zambian dataset, also with Corg and Stot.ConclusionsBased on measurements of total Hg in soils from the mining/smelting areas in Namibia and Zambia, only one fourth of the samples exceeded geochemical anomaly thresholds, and they indicated a relatively low level of Hg pollution. Elevated Hg concentrations were only observed in topsoils in the immediate vicinities of mine tailings and active smelters. Constructed regression models were found to be useful for prediction of Hg concentrations at both of the regions studied.

Science of The Total Environment, 2010

The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental ... more The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental approach. Arsenopyrite in nylon experimental bags was placed in individual horizons in soils in spruce (litter, horizons A, B, and C), beech (litter, horizons A, B, and C) and unforested (horizons A, B, and C) areas and left in contact with the soil for a period of 1 year. The individual areas on the ridge of the Krusné hory Mts., Czech Republic, had the same lithology, climatic and environmental conditions. Scorodite (FeAsO(4).2H(2)O) was identified as a principal secondary mineral of arsenic (As) formed directly on the surface of the arsenopyrite. Scorodite was formed in all the areas in all soil horizons. The amount of scorodite formed decreased in the series beech, spruce and unforested areas. In forested areas, there was a larger amount of scorodite on arsenopyrites exposed in organic horizons (litter, A horizon). The greater rate of arsenopyrite alteration in organic horizons in the beech stand compared to spruce stand is probably a result of faster mineralization of organic material with resulting production of nitrate and better seepage conditions of soil in this area. Speciation of As determined using the sequential extraction technique demonstrated that As was bonded in the soils primarily in the residual fractions prior to the experiment. The As content in the mobile fractions increased in the organic horizon in the forested areas after the experiments.

Mineralogical Magazine, 2004

The major- and trace-element chemistry of pyrite and arsenopyrite from the mesothermal Roudný gol... more The major- and trace-element chemistry of pyrite and arsenopyrite from the mesothermal Roudný gold deposits was studied by electron microprobe and laser ablation ICP-MS techniques. In total, four generations of pyrite and two of arsenopyrite were distinguished. The pyrite is enriched in As through an Fe (AsxS1–x)2 substitution mechanism. The As-rich zones of pyrite-2 (up to 4.5 wt.% As) are also enriched in gold (up to 20 ppm), lead (commonly up to 220 ppm, exceptionally up to 1500 ppm) and antimony (commonly <600 ppm, rarely up to 1350 ppm). Positive correlation of As and Au in the studied pyrites is not coupled with an Fe deficiency, in contrast to Au-rich As-bearing pyrites in Carlintype gold deposits. The As-rich pyrite-2 coprecipitated with the Sb-rich (1 –4.2 wt.%) and Au-rich (40 –150 ppm) arsenopyrite-1. The younger arsenopyrite-2 is significantly less enriched in these elements (0 –70 ppm of Au).The chemical zonality of pyrites in the Roudný gold deposits reflects the ch...