Secondary Minerals Research Articles

Application of Antimony Stable Isotopes in Revealing the Source and Vertical Migration of Sb in Soil.

Antimony (Sb) is a widespread contaminant that poses potential carcinogenic risks worldwide. Many countries are grappling with significant historical Sb-containing waste, leading to soil contamination, which is of international concern. The lack of clarity on Sb sources and migration mechanisms in soil limits the effective prevention and control of soil pollution. This study utilized Sb stable isotope techniques to analyze soil profiles from two pollution scenarios, with the aims of quantifying Sb sources, understanding migration processes, and elucidating isotopic fractionation mechanisms in soil. The results reveal that surface soil Sb originates primarily from atmospheric dry deposition (31.7-56.3%), wet deposition (19.6-32.7%), and rock weathering (<21.0%). In subsurface soils, Sb mainly comes from solutions resulting from desorption in upper soil layers, with adsorption by iron minerals, manganese (hydr-)oxides, and organic matter impeding its downward movement. Deeper soil layers contain Sb derived from parent rock weathering, with migration impacted by secondary mineral adsorption. Groundwater aids in Sb migration and influences isotopic fractionation during water-soil exchange. This research introduces a novel framework for quantitatively tracking Sb pollution and enhances the scientific understanding of the geochemical behavior of Sb in soil.

Effect mechanism of low-molecular-weight organic acids during sulfidation of As(V)-bearing ferrihydrite.

Effect mechanism of low-molecular-weight organic acids during sulfidation of As(V)-bearing ferrihydrite.

Contrasting kinetics of arsenic release from As-bearing ferrihydrite coprecipitates by distinct sulfate-reducing bacteria.

Contrasting kinetics of arsenic release from As-bearing ferrihydrite coprecipitates by distinct sulfate-reducing bacteria.

Microbial Fe(III) reduction across a pH gradient: The impacts on secondary mineralization and microbial community development.

Microbial Fe(III) reduction across a pH gradient: The impacts on secondary mineralization and microbial community development.

Formation of an anthropogenic rock: mechanisms and microstructures of lithification of a legacy deposit of cementitious material

Billions of tonnes of anthropogenic geomaterials, such as slags, ashes and cementitious materials, are deposited on the Earth's surface globally every year. These materials have the potential to become rock but little is known about how they may become lithified. In this study, we document lithification of a legacy deposit of cementitious material at a former cement works in Scotland, and uncover the mechanisms and drivers for its conversion from a loose granular sediment to an anthropogenic rock. Optical and electron microscopy and chemical mapping, coupled with X-ray diffraction, indicate the presence of particles of waste cementitious material interpreted to be calcium–silicate–hydrate (C-S-H) formed through hydration of cement clinker; these particles are rimmed by a secondary calcite mineral cement which binds the C-S-H particles together. Partial dissolution of C-S-H followed by diffusion of Ca and OH − into porewaters promoted ingassing and hydroxylation of atmospheric CO 2 (fingerprinted by carbon isotope analysis). The CO 2 reacted with the dissolved Ca to precipitate the calcite cement rimming the C-S-H grains. This calcite mineral cement has therefore bonded the grains to create an anthropogenic rock. This process can potentially create benefits in terms of ground stabilization and atmospheric CO 2 sequestration.

Investigating formation processes of secondary sulfate minerals in the semi-arid climate of the Rio Puerco watershed, New Mexico using sulfur and oxygen isotopes – Implications for the origin of gypsum veins in Gale crater on Mars

Investigating formation processes of secondary sulfate minerals in the semi-arid climate of the Rio Puerco watershed, New Mexico using sulfur and oxygen isotopes – Implications for the origin of gypsum veins in Gale crater on Mars

Geochemical behavior of iron-sulfur coupling in coastal wetland sediments and its impact on heavy metal speciation and migration.

Geochemical behavior of iron-sulfur coupling in coastal wetland sediments and its impact on heavy metal speciation and migration.

Geochemistry of laterite around UNESCO World Heritage Sites in Kamphaeng Phet, Thailand

UNESCO World Heritage Sites in Kamphaeng Phet, Thailand, once part of the Sukhothai Kingdom, are built with laterite (e.g., temples, pagodas, and city walls). Four laterite deposits (Lan Dokmai Tok, Nong Pling, Phran Kratai, and Nong Hua Wua) have been found in the immediate vicinity and may have served as sources for construction materials. However, no studies have been conducted on this topic in the region. This study aims to analyze the geochemistry of laterite from four sites to explore and improve our understanding of their formation stages and processes. Field investigations identified various morphological types of nodular laterite, including vermiform, pisolitic, pisolith, and ferruginised. Darker-colored laterites (black, brown, and red) have greater relative hardness compared to their lighter-colored counterparts (pink, yellow, and white). Based on XRD and XRF analysis, the darker-colored laterites contain high concentrations of secondary iron minerals (hematite, goethite, and/or magnetite) and high iron oxide contents (>35 wt.%). In contrast, lighter-colored laterites predominantly comprise secondary clay minerals (kaolinite, montmorillonite, and/or muscovite) and exhibit lower iron oxide contents. Based on SiO2, Al2O3 and Fe2O3 concentrations, these laterites have undergone moderate to strong laterization processes. The presence of gabbro core stones and minerals such as hercynite and fayalite in laterite samples from Lan Dokmai Tok suggests that gabbro is the parent rock. In a tropical climate, the parent rock undergoes weathering processes for a long period, resulting in secondary clay and iron minerals. The concentration of the iron minerals has been controlled by different conditions such as water table levels and surrounding geological features (e.g., bedrock type, or faults). The geomorphological setting and thickness of all laterite sites indicate in situ formation. All tested laterites are suitable building materials and were likely integral for constructing historical sites. These findings can provide valuable information for archeological research in the region.

Variation of Mg isotopes during mineral dissolution at pH = 1 and T = 25 °C: Part 1. Hornblende and chlorite

BackgroundSilicate mineral weathering, particularly involving Mg-bearing minerals like hornblende and chlorite, plays a crucial role in the global geochemical cycle of magnesium. This process is intrinsically linked to carbon sequestration and climate regulation. Mg isotopes offer a valuable tool to investigate the complex interplay between climate and silicate weathering. In this study, we aimed to elucidate the mechanisms and extent of Mg isotope fractionation during the dissolution of hornblende and chlorite under far–from–equilibrium conditions in a plug-flow reactor. By understanding these processes, we can gain insights into the behavior of Mg isotopes in natural environments and their potential as a paleoclimate proxy.MethodsHornblende and chlorite minerals were mechanically disaggregated, sieved to a particle size range of 63–245 µm, and subsequently used in dissolution experiments. These experiments were conducted in a plug–flow reactor under far-from-equilibrium conditions. A 0.1M HCl solution was continuously pumped through columns containing the minerals. Effluent solutions were collected over a duration of 2061 h. Elemental concentrations and Mg isotopic compositions of these solutions were determined using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP–OES) and Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC–ICP–MS), respectively.ResultsElemental concentrations exhibited distinct temporal trends for both minerals. During hornblende dissolution, concentrations peaked at 4 h and subsequently decreased to near-zero levels by the end of experiment. In contrast, chlorite dissolution resulted in a rapid decline in elemental concentrations until 20 h, followed by a steady–state phase for the remainder of the experiment. Hornblende exhibited a δ26Mg value of − 0.24‰, while its leachates (exchangeable, weakly bound, and structural Mg) displayed δ26Mg values of − 0.62‰, − 0.72‰, and − 0.26‰, respectively. Similarly, chlorite possessed a δ26Mg value of − 0.24‰, but its leachates yielded δ26Mg values of − 0.36‰, − 0.62‰, and − 0.18‰, respectively. Solution δ26Mg values ranged from − 0.65‰ at 4 h to − 0.20‰ at 45 h, ultimately stabilizing at − 0.35‰ during hornblende dissolution, while solution δ26Mg values varied from − 0.66‰ at 4 h to − 0.23‰ at 20 h, eventually reaching a steady–state value of − 0.40‰ during chlorite dissolution.ConclusionsThe output solutions displayed initial periods of rapid, incongruent mineral dissolution, followed by a transition to a quasi–steady–state dissolution regime. The δ26Mg values of the solutions during hornblende and chlorite dissolution fell within the range of δ26Mg values for “labile” and “structural” Mg of each mineral, suggesting that the solution δ26Mg reflects a mixture of different Mg pools with distinct isotopic compositions. This study indicates that δ26Mg variations during mineral dissolution are comparable to Mg isotope fractionation during secondary mineral formation, implying that labile Mg can exert a significant influence on the Mg isotope geochemistry of rivers draining silicate-rich regions.

CO2 geological sequestration can remove emerging contaminants in groundwater: The important role of secondary mineral carbonates.

CO2 geological sequestration can remove emerging contaminants in groundwater: The important role of secondary mineral carbonates.

Enhanced Leaching of Lepidolite by Acidophilic Microorganisms Under Mechanical Activation.

In recent years, mechanical activation technology has been extensively applied as a pretreatment process to increase the leaching efficiency in hydrometallurgical mineral processing. However, studies on its application in the lepidolite bioleaching process are limited. Therefore, the effects of mechanical activation on lithium extraction by an acidophilic iron/sulfur-oxidizing microbial community under different nutrient conditions were evaluated in this study. The solution behavior, phase morphology, and compositional evolution, and microbial community structure succession under eutrophic conditions with exogenous pyrite as the energy substrate and oligotrophic conditions, were investigated. The results revealed that mechanical activation significantly influences the microbial community structure and the interrelationship between microbial activity and mineral phase decomposition and transformation by altering the physical and chemical properties of lepidolite. The best leaching effect was observed in the eutrophic bioleaching groups, followed by the oligotrophic groups at all mechanical activation times. Notably, at a rotation speed of 200 r/min, a material-to-ball mass ratio of 1:20, and an activation time of 150 min, the maximum leaching rates of lithium under eutrophic and oligotrophic conditions were 24.9% and 20.8%, respectively, which were 20.0% and 17.9% higher than those of the nonactivated group. The phase and composition analyses indicated that the dissolution of lithium silicate minerals occurs through a combination of protic acid corrosion, the complexation/electrostatic interactions of extracellular polymeric substances, and the complexation of secondary minerals. These results indicate that the leaching effect is closely related to the pretreatment of mechanical activation, the energy substrates, and the microbial community structure, and this has important reference value for the optimization of the bioleaching process of lepidolite.

Перспективные агрохимикаты на основе вторичного минерального сырья предприятий лесопромышленного комплекса

As a result of activity of enterprises of the timber industry complex for the production of paper products, significant volumes of secondary mineral raw materials are formed, which need to be utilized. Soil liming is a promising direction of utilization of such raw materials. By methods of X-ray diffraction, X-ray fluorescence and thermal analyses, mass spectrometry with inductively-coupled plasma, radiological studies the material composition of secondary mineral resources of Syktyvkar TP (dust of electric filters of furnaces, slaked lime obtained from substandard calcium oxide, bark and wood ash) has been determined. The determined features of changes in phase and chemical composition of secondary raw materials allowed to develop original compositions of agrochemicals named “Edemit” and “Pushonka plus”, which were tested for soil liming on the experimental field. It was found that liming contributed to the increase of soil pH value from 4.6 to 6.6 on average, the degree of saturation with bases up to 44—92 % and decrease of hydrolytic acidity twice as compared to the control variant.

Concentration-discharge relations and transient metal loads reveal spatiotemporal variability in solute-generation mechanisms in a mine-affected watershed.

Concentration-discharge relations and transient metal loads reveal spatiotemporal variability in solute-generation mechanisms in a mine-affected watershed.

Rapid subsidence as a driver of phosphate deposition in the later Ordovician: Case study from the Alabama Appalachians

Rapid subsidence as a driver of phosphate deposition in the later Ordovician: Case study from the Alabama Appalachians

An Anaerobic Microbial Community Mediates Epigenetic Native Sulfur and Carbonate Formation During Replacement of Messinian Gypsum at Monte Palco, Sicily.

The microbially mediated replacement of sulfate-bearing evaporites by authigenic carbonate and native sulfur under anoxic conditions is poorly understood. Sulfur-bearing carbonates from the Monte Palco ridge (Sicily) replacing Messinian gypsum were therefore studied to better characterize the involved microorganisms. The lack of (1) sedimentary bedding, (2) lamination, and (3) significant water-column-derived lipid biomarkers in the secondary carbonates implies replacement after gypsum deposition (epigenesis). Allochthonous clasts from the older Calcare di Base and the younger Trubi Formation within these carbonates further evidence epigenetic formation. The sulfur-bearing carbonates are significantly 13C-depleted (δ13C as low as -51‰), identifying methane as a major carbon source. The 18O-enrichment of the carbonates (δ18O as high as 5.4‰) probably reflects precipitation from 18O-enriched fluids transported along adjacent faults or precipitation in a closed system with very little water. Native sulfur with variable 34S-enrichment (δ34S as high as 18.9‰), a relatively small maximum offset (12.3‰) between the sulfate source (gypsum) and native sulfur, and high δ34S values of carbonate-associated sulfate (as high as 61.1‰) suggest a high conversion to native sulfur in a (semi-)closed system, with insignificant sulfate removal. Anaerobic methanotrophic archaea (ANME) apparently affiliated with the ANME-1 clade mediated secondary mineral formation as evidenced by the biomarker inventory, which contains abundant 13C-depleted isoprenoids including sn3-hydroxyarchaeol as the sole hydroxyarchaeol isomer and glycerol dibiphytanyl glycerol tetraethers (GDGTs). A series of various, tentatively identified 13C-depleted non-isoprenoidal dialkyl glycerol diethers (DAGEs), 10me-C16 fatty acid, hydroxy C16 fatty acids, and cyclopropyl-C17:0ω7,8 fatty acid agree with sulfate-reducing bacteria participating in the anaerobic oxidation of methane. Specific conditions during gypsum replacement, unlike those at marine methane seeps, are reflected by the occurrence of 13C-depleted lipids such as lycopane, 9me-C17 fatty acid, and novel DAGEs. As a response to a confined environment probably characterized by high sulfate concentrations, sulfidic conditions, and elevated salinity, ANMEs and sulfate-reducing bacteria apparently adapted their membrane compositions to cope with such stressors.

Chloride corrosion destabilizes chelation of fresh and aged MSWI fly ash: Mechanism and long-term behavior.

Chloride corrosion destabilizes chelation of fresh and aged MSWI fly ash: Mechanism and long-term behavior.

Self-modified iron-based materials for efficient chromium (VI) removal: Efficacy and mechanism.

Self-modified iron-based materials for efficient chromium (VI) removal: Efficacy and mechanism.

Pb alleviates As mobilization during the biological reductive dissolution of Pb-As jarosite.

Pb alleviates As mobilization during the biological reductive dissolution of Pb-As jarosite.

Elucidating the hydrochemistry and REE evolution of surface water and groundwater affected by acid mine drainage.

Elucidating the hydrochemistry and REE evolution of surface water and groundwater affected by acid mine drainage.

Trace element transport by volcanic gases at Vulcano (Sicily, Italy) – Speciation, deposition and fluxes

Trace element transport by volcanic gases at Vulcano (Sicily, Italy) – Speciation, deposition and fluxes