Geometallurgy of Trace Elements in the Hrazdan Iron Deposit

This study presents an evaluation of arsenic and other trace metals in the Hrazdan Iron-Ore project in Armenia using a methodology typically associated with Geometallurgical characterization. The principal host of the trace elements is pyrite and oxidized equivalents. Pyrite is a mineral of elemental concern as it has the potential to generate acidic pH in water that it contacts and thus mobilize metals of concern. In the Hrazdan deposit, there is a general excess of neutralizing carbonate minerals that result in adequate buffering of generated acid and limiting the mobility of metal cations in solution. However, metalloids that form oxyanions species such as those of arsenic or chromium tend to be more mobile in neutral to alkaline mine drainage. From the geometallurgical assessment of the mine waste, the results of the geochemical testwork can be explained and the information used to assess potential issues with mine waste storage, timing of metal release and provide a baseline for mitigation strategies.

Neoteric Material Based on Renewable Resources for Metal-Contaminated Waters

A continuous increase of environmental pollution has been recorded worldwide, during recent decades, as a result of industrialization and urbanization. In particular, metal release in the environmental media may threaten human health, due to their persistence and accumulation in the food chain. We report here the functionalization of chitosan with poly(benzofurane-co-arylacetic) acid, which is a new material with the ability of complex metals from contaminated water. The synthesized polymer was structurally investigated by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray photon electron microscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR), while heavy metals were determined by atomic absorption spectrometry. Different isotherms and kinetic models were used to describe the absorption equilibrium and the behavior of the material, based on the initial pollutant concentration and contact time. The results are pointing out that such natural materials can be easily synthesized, at low costs, thus offering attractive solutions for wastewater treatment.

Perchlorate and Agriculture on Mars

Perchlorate (ClO4−) is globally enriched in Martian regolith at levels commonly toxic to plants. Consequently, perchlorate in Martian regolith presents an obstacle to developing agriculture on Mars. Here, we assess the effect of perchlorate at different concentrations on plant growth and germination, as well as metal release in a simulated Gusev Crater regolith and generic potting soil. The presence of perchlorate was uniformly detrimental to plant growth regardless of growing medium. Plants in potting soil were able to germinate in 1 wt.% perchlorate; however, these plants showed restricted growth and decreased leaf area and biomass. Some plants were able to germinate in regolith simulant without perchlorate; however, they showed reduced growth. In Martian regolith simulant, the presence of perchlorate prevented germination across all plant treatments. Soil column flow-through experiments of perchlorate-containing Martian regolith simulant and potting soil were unable to completely remove perchlorate despite its high solubility. Additionally, perchlorate present in the simulant increased metal/phosphorous release, which may also affect plant growth and biochemistry. Our results support that perchlorate may modify metal availability to such an extent that, even with the successful removal of perchlorate, Martian regolith may continue to be toxic to plant life. Overall, our study demonstrates that the presence of perchlorate in Martian regolith provides a significant challenge in its use as an agricultural substrate and that further steps, such as restricted metal availability and nutrient enrichment, are necessary to make it a viable growing substrate.

Metal Ion Release from Engineered Stone Dust in Artificial Lysosomal Fluid—Variation with Time and Stone Type

Inhalational exposure to dust from engineered stone (ES), also known as artificial or composite stone, is associated with a specific disease profile, namely accelerated silicosis, and scleroderma. The pathogenic mechanisms are poorly understood, particularly the role of resin and metal ions. Metal ions are present in pigments and constituent minerals and may be considered potential contributors to toxicity. The aim of this preliminary study was to understand the solubility of ES-containing metals in artificial lysosomal fluid (ALF) simulating the acidic intracellular environment of the lung macrophage lysosome. Differences with respect to ES types and temporal release were explored. Ten ES products of variable colour and company origin were comminuted and assessed for four different metals, solubilized into ALF solutions at 1,2,4 and 8 weeks at 37 °C. There was significant variability in metal release, particularly with regard to iron and manganese, which could be correlated with the reflected brightness of the stone. A majority of the available Mn, Fe, Al and Ti was solubilized. Time trends for metal release varied with ES type but also with metal ion. The data suggest a high metal ion bioavailability once engulfed by lung macrophages. There is a need to investigate a wider range of ES dust and relate metal content to markers of ES toxicity.

Metagenome-assembled genomes infer potential microbial metabolism in alkaline sulphidic tailings

Background Mine tailings are hostile environment. It has been well documented that several microbes can inhabit such environment, and metagenomic reconstruction has successfully pinpointed their activities and community structure in acidic tailings environments. We still know little about the microbial metabolic capacities of alkaline sulphidic environment where microbial processes are critically important for the revegetation. Microbial communities therein may not only provide soil functions, but also ameliorate the environment stresses for plants’ survival. Results In this study, we detected a considerable amount of viable bacterial and archaeal cells using fluorescent in situ hybridization in alkaline sulphidic tailings from Mt Isa, Queensland. By taking advantage of high-throughput sequencing and up-to-date metagenomic binning technology, we reconstructed the microbial community structure and potential coupled iron and nitrogen metabolism pathways in the tailings. Assembly of 10 metagenome-assembled genomes (MAGs), with 5 nearly complete, was achieved. From this, detailed insights into the community metabolic capabilities was derived. Dominant microbial species were seen to possess powerful resistance systems for osmotic, metal and oxidative stresses. Additionally, these community members had metabolic capabilities for sulphide oxidation, for causing increased salinity and metal release, and for leading to N depletion. Conclusions Here our results show that a considerable amount of microbial cells inhabit the mine tailings, who possess a variety of genes for stress response. Metabolic reconstruction infers that the microbial consortia may actively accelerate the sulphide weathering and N depletion therein.