Arsenic-rich stalactites in abandoned mines

Arsenic-rich stalactites (0.13-294 g/kg As)  collected from abandoned adits of the Plavno and Mikulov mines (NW Czech Republic) consist of HFA, HFO, kaňkite, schwertmannite, and hydrous manganese oxide mineral phases. These phases were often combined in one stalactite, forming domains, layers and coprecipitates. The microbial communities indicated autotrophic oxidation of Fe(II), As(III), and reduced sulphur compounds as the most notable biological processes influencing the mineralogy in studied stalactites.



Jelenová H., Drahota P., Falteisek P., Culka A. (2021): Arsenic-rich stalactites from abandoned mines: Mineralogy and biogeochemistry. Applied Geochemistry 129, 104960. (DOI)

Plenary talk at the 7th Slag Valorization Symposium

Vojtěch Ettler will give a plenary lecture entitled “The leaching behavior of smelting slags: from contaminants to critical metals” on the 7th International Slag Valorization Symposium (SVS7). The conference, originally planned to take place in Leuven, Belgium, will finally run in a virtual mode. SVS7 is a major event on characterization and applications of metallurgical slags and will bring together people from R&D sector and industry.

Mobility of As in sulfidic gley soils during drought

We combined selective chemical extractions and S isotopes to examine the mobility of As and trace metals (Co, Cu, Ni) in two Czech wetland soils enriched in authigenic Fe-As sulfide minerals through the drying process. We found that As and trace metals released via oxidation of the sulfide phases (particularly Fe sulfides) were almost entirely sequestered by Fe(III) (oxyhydr)oxides, but concomitant acidification resulted in the pH-dependent release of the As(III) and trace metals. Although our results documented the relatively low As mobilization potential under relatively short droughts (several weeks), the preservation of the anoxic conditions must be regarded as a fundamental management strategy of these and other sulfidic wetlands enriched in As.

Drahota P., Peřestá M., Trubač J., Mihaljevič M., Vaněk A. (2021): Arsenic fractionation and mobility in sulfidic wetland soils during experimental drying. Chemosphere 277, 130306. (DOI)

African Pb-Zn slags: a potential source of vanadium?

Vanadium is a key critical metal with many applications in the steel and chemical industry. Slags issued from the metallurgical processing of Pb-Zn vanadate ores at Berg Aukas (Namibia) and Kabwe (Zambia) exhibit interestingly high concentrations of V (up to 6140 ppm) and can be considered potential sources of this metal. Two papers published recently by our research group focused on geochemistry and mineralogy of these slags combined with laboratory simulation of the hydrometallurgical extractive processes in view of potential V recovery. The results indicate that, despite high V bulk concentrations and extractabilities, its recovery seems to be non-economical, mainly due to low prices of V (and other associated valuable elements such as Zn) on the global market.

Ettler V., Mihaljevič M., Jarošíková A., Culka A., Kříbek B., Majer V., Vaněk A., Penížek V., Sracek O., Mapani B., Kamona F. (2020): Vanadium-rich slags from the historical processing of Zn-Pb-V ores at Berg Aukas (Namibia): Mineralogy and environmental stability. Applied Geochemistry 114, 104473. (DOI)

Ettler V., Jarošíková A., Mihaljevič M., Kříbek B., Nyambe I., Kamona F., Mapani B. (2020): Vanadium in slags from smelting of African Pb-Zn vanadate ores: Mineralogy, extractability and potential recovery. Journal of Geochemical Exploration 218, 106631. (DOI)

AutoSEM techniques applied to contaminated soils

Automated mineralogy has been used to quantitatively determine the contaminant partitioning in the soil particulates originating from heavily polluted mining/smelting sites. This method provides faster data acquisition, the full integration of the quantitative EDS data and better detection limits for the elements of interest. AutoSEM was found to be a useful tool for the determination of the modal phase distribution and element partitioning in the metal(loid)-bearing (As, Cu, Pb, Zn) soil particulates and will definitely find more applications in environmental soil sciences in the future.

Tuhý M., Hrstka T., Ettler V., Automated mineralogy for quantification and partitioning of metal(loid)s in particulates from mining/smelting-polluted soils. Environmental Pollution 266: 115118. (DOI(open-access)

Wildfires and Hg remobilization

Mercury distribution in topsoils and vegetation samples and temperature-dependent Hg mobilization simulating wildfires have been investigated near a Cu smelter in semi-arid Namibia. The thermo-desorption experiments performed on the representative Hg-rich topsoils indicated that >91% of the Hg was released at ~340°C, which corresponds to the predominant grassland-fire conditions. Despite the installation of a sulfuric acid plant in the smelter in 2015 and a calculated drop in the estimated Hg emissions (from 1301 ± 457 kg/y for the period 2004-2015 to 67 ± 5 kg/y after 2015), the Hg legacy pool in the smelter surroundings will contribute to wildfire-driven Hg emissions until its complete burn-out. Using the Hg spatial distribution data in the area (184 km2), the estimates indicate that up to 303 kg and 1.3 kg can be remobilized from the topsoils and vegetation, respectively.

Tuhý M., Rohovec J., Matoušková Š., Mihaljevič M., Kříbek B., Vaněk A., Mapani B., Göttlicher J., Steininger R., Majzan J., Ettler V. (2020): The potential wildfire effects on mercury remobilization from topsoils and biomass in a smelter-polluted semi-arid area. Chemosphere 247, 125972. (DOI)

Lecture by Karen Hudson-Edwards

Karen Hudson-Edwards, Professor in Sustainable Mining at University of Exeter (UK), will give a lecture entitled „Environmental Minerals: Bacteria, Worms, Dusts, Toxins and the Human Body“ on Monday 13th January 2020 at 3 pm in Ložiskové sbírky (room no. 120, Albertov 6 building, Faculty of Science, Charles University). The lecture takes part of the European Association of Geochemistry Lecture Tour and is partly supported by Center for Geosphere Dynamics. You are cordially invited!

Second paper of arsenic sulfidation under the low-temperature conditions in the Geochimica et Cosmochimica Acta

This study investigated As-enriched wetland at the Smolotely-Líšnice Au district (Centra Bohemia) using the combination of geochemical (soil and pore water analyses, S isotopes), mineralogical (microprobe, Raman spectrometry) and biological (DNA extraction) method. In this paper, Magda and her co-authors identified a complex assemblage of As and Fe sulfides (realgar, bonazziite, pyrite, greigite) on the fragments of natural organic matter, which play an active role (very fast microbial sulfate reduction vs. slow transfer of solutes) in arsenic immobilization in polluted wetland systems.

Knappová M., Drahota P., Falteisek L., Culka A., Penížek V., Trubač J., Mihaljevič M., Matoušek T. (2019): Microbial sulfidogenesis of arsenic in naturally contaminated wetland soil. Geochimica et Cosmochimica Acta 267, 33-50.