Natural Mine Water Research Articles

The Diverse Indigenous Bacterial Community in the Rudna Mine Does Not Cause Dissolution of Copper from Kupferschiefer in Oxic Conditions

Blasting and fracking of rock in mines exposes fresh rock surfaces to the local water and microbial communities. This may lead to leaching of metals from the rock by chemical or biological means and can cause acidification of the water system in the mine, i.e., acid rock drainage (ARD). Failure to prevent leakage of metal contaminated mine water may be harmful for the environment, especially to the local groundwater. In the Rudna mine, Poland, an in situ bioleaching pilot test at approximately 1 km depth was performed in the H2020 BIOMOre project (Grant Agreement #642456). After the leaching stage, different methods for irreversible inhibition of acidophilic iron oxidizing microorganisms used for reoxidation of reduced iron in the leaching solution were tested and were shown to be effective. However, the potential of the natural mine water microbial communities to cause leaching of copper or acidification of the mine waters has not been tested. In this study, we set up a microcosm experiment simulating the exposure of freshly fractionated Kupferschiefer sandstone or black schist to two different chloride-rich water types in the Rudna mine. The pH of the microcosms water was measured over time. At the end of an 18-week incubation, the bacterial community was examined by high throughput sequencing and qPCR, and the presence of copper tolerant heterotrophic bacteria was tested by cultivation. The dissolution of copper into the chloride rich microcosm water was measured. The pH in the microcosms did not decrease over the time of incubation. The sandstone increased the number of bacteria in the microcosms with one or over two orders of magnitude compared to the original water. The bacterial communities in the two tested mine waters were diverse and similar despite the difference in salinity. The bacterial diversity was high but changed in the less saline water during the incubation. There was a high content of sulphate reducing bacteria in the original mine waters and in the microcosms, and their number increased during the incubation. No acidophilic iron oxidizers were detected, but in the microcosms containing the less saline water low numbers of Cu tolerant bacteria were detected. Copper to a concentration of up to 939 mg L−1 was leached from the rock also in the microbe-free negative controls, which was up to 2.4 times that leached in the biotic microcosms, indicating that the leaching was also abiotic, not only caused by bacteria.

Selective adsorption of U(VI) from real mine water using an NH2-functionalized silica packed column

The adsorption of U(VI) from natural mine water (i.e. containing Na+, K+, Ca2+, Mg2+ as major cations, and Cl−, SO42− and HCO3− as major anions) was investigated in dynamic mode using packed column containing high-capacity sorbents modified by NH2 organic moieties. The use of packed columns was effective in removing trace amounts of U(VI) species in natural water. The adsorption capacity obtained with amine functionalized SBA-15, a mesostructured silica, was compared with those obtained with commercial cationic exchange resin and grafted commercial silica. Hybrid mesoporous silica and particularly SBA-15, were found to be very effective and selective for U(VI) removal from mine water (C0 ~ 300 ppbU) since 500 mg of adsorbent was able to remove U(VI) species present in 6 L of water. Nevertheless, our results showed that mesostructuration did not play a major role in adsorbent capacity, and that only the amine functional group density was important for the U(VI) aqueous removal. This finding was very important because cheaper commercial silica can be used instead of mesostructured silica such as SBA-15. Furthermore, the role of competitor ions Ca2+ and HCO3−, commonly found in natural waters, was also studied by performing adsorption experiments with synthetic solutions representative of mine waters. Results coupling aqueous speciation modelling and XPS measurements showed that hydrogen carbonate ions had a negative impact for U(VI) species adsorption on amino modified silica. Results however demonstrated that amine-grafted silica could be considered a very promising material for the removal of trace level of uranium from mine water.

GDMS Analysis Of Calcium Carbonate Naturaly Doped By REE, Phospates And Other Impurities

A mathematical model was developed for calculation of types and intensities of molecular interferences and simulation of mass-spectra at GDMS analysis of non-conducting samples with the use of a secondary cathode. An improved design of the cell with Ta-secondary cathode were suggested enhancing the matrix to tantalum ion current ratio and sensitivity of the analysis in ca. 1.5 orders of magnitude. The model have been used for interpretation of complicate mass-spectra of calcium carbonate naturally doped with REE, phosphates and other impurities. Comparison calculated and experimental mass-spectra of VG9000 instrument demonstrates good agreement and allows select the most suitable isotopes and rejecting wrong molecular peaks. It have been shown that electrons in glow discharge plasma have different temperatures in different zones that reveals itself as separate Boltzmann populations of ionization levels for molecules, metal atoms and argon atoms/ions. Calcium carbonate is widely used for many application including as precursor for nano-hydroxyapatite synthesis. Calcium carbonate was precipitated from natural mine waters and was used as model object having high number of various impurities allowing to investigate the impact of complicate molecular ions, determine necessary resolving power of the GD-instruments to meet required detection limit.