The Puna region is distinguished by its extreme environmental conditions and highly valuable mining resources. However, the unregulated management of mine tailings poses a significant threat to the ecological integrity of this region. This study assesses the environmental impacts of mine tailings at La Concordia mine (Salta province, Argentina) and examines the physiological and biochemical adaptations of Parastrephia quadrangularis (Meyen) Cabrera that enable its survival under this extreme conditions. Our findings reveal that prolonged weathering of mine tailings results in the generation of acid mine drainage characterized by low pH levels (< 3.5) and elevated concentrations of As, Fe, Cu, Pb, and Zn. These levels exceed drinking water standards by 5-10 times for As, 6-13 times for Zn, 80-120 times for Pb, 20-380 times for Fe, and 4-10 times for Cu. Soil analyses highlight low pH, high salinity, and elevated concentrations of Zn (310 mg kg(-1)), Pb (153 mg kg(-1)), and Cu (128 mg kg(-1)). Despite these harsh environmental conditions, 7 plant species where identified, with Parastrephia quadrangularis being the only species present at the most polluted site. This species exhibits high heavy metal bioaccumulation and robust tolerance mechanisms against heavy metal-induced oxidative damage, as evidenced by stable total chlorophylls and malondialdehyde content, and increased levels of carotenoids, proline, and phenolic compounds. These findings emphasize Parastrephia quadrangularis as a promising candidate for revegetation and phytostabilization for sustainable mine closure programs in La Puna region.

More information is needed to fully comprehend how acid mine drainage (AMD) affects the phototransformation of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in karst water and sewage -irrigated farmland soil with abundant carbonate rocks (CaCO 3 ) due to increasing pollution of AMD formed from pyrite (FeS 2 ). The results showed FeS 2 accelerated the inactivation of ARB with an inactivation of 8.7 log. Notably, extracellular and intracellular ARGs and mobile genetic elements (MGEs) also experienced rapid degradation. Additionally, the pH of the solution buffered by CaCO 3 significantly influenced the photo -inactivation of ARB. The Fe 2 + in neutral solution was present in Fe(II) coordination with strong reducing potential and played a crucial role in generating center dot OH (7.0 mu M), which caused severe damage to ARB, ARGs, and MGEs. The center dot OH induced by photo -Fenton of FeS 2 posed pressure to ARB, promoting oxidative stress response and increasing generation of reactive oxygen species (ROS), ultimately damaging cell membranes, proteins and DNA. Moreover, FeS 2 contributed to a decrease in MIC of ARB from 24 mg/L to 4 mg/L. These findings highlight the importance of AMD in influencing karst water and sewage -irrigated farmland soil ecosystems. They are also critical in advancing the utilization of FeS 2 to inactivate pathogenic bacteria.

Acid mine drainage (AMD) is one of the leading causes of environmental pollution and is linked to public health and ecological consequences. Microbes-mineral interaction generates AMD, but microorganisms can also remedy AMD pollution. Exploring the microbial response to AMD effluents may reveal survival strategies in extreme ecosystems. Three distinct sites across a mine (inside the mine, the entrance of the mine, and outside) were selected to study their heavy metal concentrations due to significant variations in pH and physicochemical characteristics, and high-throughput sequencing was carried out to investigate the microbial diversity. The metal and ion concentrations followed the order SO42 , Fe, Cu, Zn, Mg, Pb, Co, Cr, and Ni from highest to lowest, respectively. Maximum sequences were allocated to Proteobacteria and Firmicutes. Among archaea, the abundance of Thaumarchaeota and Euryarchaeota was higher outside of mine. Most of the genera (23.12 %) were unclassified and unknown. The average OTUs (operational taxonomic units) were significantly higher outside the mine; however, diversity indices were not significantly different across the mine sites. Hierarchical clustering of selective genera and nMDS ordination of OTUs displayed greater segregation resolution inside and outside of mine, whereas the entrance samples clustered with greater similarity. Heterogeneous selection might be the main driver of community composition outside the mine, whereas stochastic processes became prominent inside the mine. However, the ANOSIM test shows a relatively even distribution of community composition within and between the groups. Microbial phyla showed both positive and negative correlations with physicochemical factors. A greater number of biomarkers were reported outside of the mine. Predictive functional investigation revealed the existence of putative degradative, metabolic, and biosynthetic pathways. This study presents a rare dataset in our understanding of microbial diversity and distribution as shaped by the ecological gradient and potential novelty in phylogenetic/taxonomic diversity in AMD, with potential biotechnological applications.

Mine site reclamation is a major concern for mining companies, especially when mine tailings are potentially acid generating mine drainage. For mine sites located in Arctic environments, many factors, such as climate change, the evolution of permafrost, remoteness, the availability of materials, and harsh climatic conditions, can make difficult the implementation of conventional rehabilitation methods. Therefore, it is necessary to design and develop reclamation approaches specific to these conditions. This study focuses on assessing the effectiveness of covers with capillary barrier effects, made of desulphurized tailings from Raglan mine (Nunavik region, Quebec). The approach would mitigate the risk of water contamination by simultaneously limiting oxygen migration into potentially acid-generating tailings, as well as reducing their temperature. The study involved a detailed characterization of the cover materials and the construction of two instrumented columns in a controlled-environment chamber (two residual sulphide level). Column tests demonstrated that capillary barrier effects induced a permanent high degree of saturation (>85%) in the moisture-retaining layer made of desulphurized tailings. This high degree of saturation impeded oxygen migration; the estimated oxygen fluxes passing through the moisture-retaining layer being lower than 5.5 x 10(-3) mol/m(2)/day for the two columns. The column containing the desulphurized tailings with the highest sulphide content was slightly more efficient in controlling the oxygen flux due to the greater oxygen consumption by residual sulphides. Results also showed that freeze-thaw cycles did not significantly affect the hydrogeological properties of the desulphurized tailings, thus indicating a stability in the long-term performance of the cover. (C) 2018 Elsevier Ltd. All rights reserved.