Nanoplastic transport in aqueous environments: The role of chemo-electric properties and hydrodynamic forces for nanoplastic-mineral interaction.

The fate and transport characteristics of nanoplastic (NP) through different environmental systems is largely governed by physio-chemical processes and their specific interaction with environmental constituents (i.e., minerals, dissolved species, suspended particles). A hydrodynamic component present in almost all terrestrial and marine aqueous environments impact the physio-chemical processes micron-scale is largely overlooked in NP transport studies. Therefore, we tested the interaction behavior of nanosized plastic polystyrene particles of various coatings in the presence of minerals abundant in the Earth crust within a hydrodynamic continuum representing flow rates from groundwater to surface water systems. Our batch experiments show that particle-mineral adsorption is largely driven by the magnitude of opposite charge configurations, which is either produced by mineral type or specific nanoplastic surface coating. Zetapotential serves as a good predictor of adsorption between uncoated and carboxyl-coated polystyrene with minerals. It fails, however, to predict adsorption behavior between NH2 coated polystyrene and apatite or feldspars, due to the more complex and varying compositions of these minerals. Incorporating the hydrodynamic force component into the particle- mineral interaction scheme reproduces those adsorption trends at slow flowrates of 1e-04 m/d. However, increasing flow rates by a factor of 100 modifies charge-driven adsorption between minerals and plastics. This study highlights the unabating importance of hydrodynamic conditions when predicting nanoplastic transport in different subsurface environments, and has implications for nanoplastic behavior in both terrestrial and marine aqueous environments.

Selective Flocculation Study of Hematite in HematiteQuartz-Kaolinite System in Presence of Ca2+, Mg2+ and Fe3+ Ions. Part1: Optimization of Ligand

Separation of ultrafine hematite from quartz and kaolinite gangue minerals using selective flocculation technique is markedly affected by the state of inter mineral interaction which is governed by type and content of polyvalent metal ions. Because of the presence of polyvalent metal ions hetracoagulation of gangue minerals is widely acknowledged, thus selective flocculation of ultrafine hematite from associated gangue minerals is challenging task when their concentration is above 10 ppm. This study has shown that state of strong interaction of gangue minerals with hematite due to presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions can be weakened by addition of optimal dose of Sodium Hexametaphosphate (SHMP) ligand. The optimization of ligand dose is achieved through analysis of Zeta Potential (ZP) as a function of slurry pH. It is noted that 50 ppm of SHMP is sufficient to restore the ZP of hematite, where selective dispersion of the slurry constituents are possible. Our results further showed that conventional strategy of obtaining minimum difference of ±30 mV in the ZP of hematite and gangue minerals quartz and kaolinite would not work especially in the presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions. Attempts to achieve the minimum threshold difference in the ZP of the minerals will cause over dispersion.

Epidote U–Pb ages vs. fluid–mineral interaction

<p>Recently, the application of LA–ICP–MS has enabled U–Pb dating of epidote minerals within the epidote–clinozoisite solid solution series (Peverelli et al., 2020). Epidote crystallization ages can provide an absolute time frame of deformation sequences when combined with detailed microstructural and metamorphic P–T analysis. Epidote deformation occurs in a brittle manner over a wide range of conditions below its closure temperature for Pb diffusion (685–750 °C; Dahl, 1997); hence, such deformation will not affect its formation U–Pb age. Nevertheless, the possibility of isotopically resetting epidote via fluid–mineral interaction has to be taken into account even at low deformation temperatures.</p><p>We investigated the geochemical and Sr–Pb isotopic characteristics of epidote in one hydrothermal vein in the Aar Massif (central Swiss Alps). The vein is associated with an Alpine shear zone and it is composed of aggregates of 0.1–1 mm anhedral to subhedral epidote grains (epidote-A) + green biotite within a quartz matrix. This quartz dynamically recrystallized by subgrain rotation at temperatures above 400 °C (Stipp et al., 2002) along with crystallization of a second epidote generation (epidote-B) made of tiny (< 0.1 mm) anhedral epidote grains in part mantling epidote-A and defining a fold. We address whether interaction with the fluid that precipitated epidote-B chemically affected epidote-A, i.e. whether the U–Pb age measured by LA–ICP–MS in epidote-A still dates its crystallization upon vein formation or displays age disturbance.</p><p>LA–ICP–MS Sr and Pb concentration data overlap between epidote-A and epidote-B, as do their REE patterns, with (La/Yb)<sub>N</sub> ratios of 0.03–0.92. Lead and Sr isotopic signatures were measured respectively by solution MC–ICP–MS and by TIMS in epidote-A and in separates mixing different proportions of epidote-A and -B (no pure mechanical separates of epidote-B possible), and they are different. This requires open-system conditions during deformation, i.e., introduction of an external fluid with higher <sup>87</sup>Sr/<sup>86</sup>Sr and <sup>208</sup>Pb/<sup>206</sup>Pb ratios during crystallization of epidote-B. Despite the presence of an external fluid and the incorporation of external Sr and Pb in epidote-B, LA–ICP–MS U–Pb isotopic data for epidote-A define a regression in a Tera–Wasserburg plot indicating an age of 19.2 ± 4.3 Ma, consistent with epidote-A crystallization during original vein opening. The preservation of the crystallization age in epidote-A indicates that interaction with the fluid that formed epidote-B did not geochemically and isotopically affect epidote-A. The consistency in trace element contents between epidote-A and -B hints that the epidote-forming cations were inherited by the fluid from epidote-A, and thus suggests dissolution-precipitation as the formation process for epidote-B.</p><p> </p><p>Dahl, Earth Planet. Sci. Lett. 150, 277–290, 1997.</p><p>Peverelli et al., Geochronology Discuss. [preprint], https://doi.org/10.5194/gchron-2020-27, in review, 2020.</p><p>Stipp et al., Geological Society, London, Special Publications, 200(1), 171-190, 2002</p>

Quality control of direct cell–mineral adhesion measurements in air and liquid using inverse AFM imaging

Setup for a reliable cell-mineral interaction at the single-cell level, (a) study of the mineral by a sharp tip, (b) study of the bacterial modified probe by a characterizer, (c) cell-mineral interaction, (d) subsequent check of the modified probe.

Visualizing Microorganism-Mineral Interaction in the Iberian Pyrite Belt Subsurface: The Acidovorax Case

Despite being considered an extreme environment, several studies have shown that life in the deep subsurface is abundant and diverse. Microorganisms inhabiting these systems live within the rock pores and, therefore, the geochemical and geohydrological characteristics of this matrix may influence the distribution of underground biodiversity. In this study, correlative fluorescence and Raman microscopy (Raman-FISH) was used to analyze the mineralogy associated with the presence of members of the genus Acidovorax, an iron oxidizing microorganisms, in native rock samples of the Iberian Pyrite Belt subsurface. Our results suggest a strong correlation between the presence of Acidovorax genus and pyrite, suggesting that the mineral might greatly influence its subsurface distribution.

Advancements and Use of OMIC Technologies in the Field of Bioleaching: A Review

Bioleaching is an environmentally safe as well as economically feasible alternative to the conventional process of metal extraction from low-grade ores. It involves the recovery of metals through microbial oxidation of metallic and/or sulfuric compounds. Wide varieties of acidophilic microbes present in the mining sites, which are necessary to decrease the pH, eventually contribute to the biomining efficiency. Ongoing development and recent advanced techniques will ensure that the implementation of genetic engineering might improve the extraction rate within less time period. The use of OMIC (genomics, proteomics, metabolomics, etc.) techniques in bioleaching is gaining interest worldwide. In the last decade, a number of studies have been carried out for the determination of bioleaching diversity, development of conceptual and functional metabolic models, analysis of microbe-mineral interaction, etc. by using various OMIC technologies. These technologies are used to improve the understanding of various microbial activities during the bioleaching process, which helps in the development of industrial-scale bioleaching process.