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Topic Review
Portable Analytical Instruments in Mineral Exploration Studies
The classic approach to mineral exploration studies was to bring the field samples/drill cores collected during field studies to the laboratory, followed by laborious analysis procedures to generate the analytical data. This is very expensive, time-consuming, and difficult for exploring vast areas. However, rapid technological advances in field-portable analytical instruments, such as portable visible and near-infrared spectrophotometers, gamma-ray spectrometer, portable X-ray fluorescence spectrometers (pXRF), portable X-ray diffractometers (pXRD), portable laser-induced breakdown spectrometers (pLIBS), and µRaman spectrometer, have changed this scenario completely and increased their on-site applications in mineral exploration studies. LED fluorimeter is a potential portable tool in the hydrogeochemical prospecting studies of uranium. These instruments are currently providing direct, rapid, on-site, real-time, non-destructive, cost-effective identification, and determination of target elements, indicator minerals and pathfinder elements in rock, ore, soil, sediment, and water samples. These portable analytical instruments are currently helping to obtain accurate chemical and mineralogical information directly in the field with minimal or no sample preparation and providing decision-making support during fieldwork, as well as during drilling operations in several successful mineral exploration programs. 
  • 1.4K
  • 08 Apr 2022
Topic Review
Photoproducts of cis-Vaccenic Acid in Oceans
Several studies set out to explain the presence of high proportions of photooxidation products of cis-vaccenic acid (generally considered to be of bacterial origin) in marine environments.
  • 225
  • 25 Jun 2023
Topic Review
Phosphorus Transport in World Rivers
Data on the geochemistry of phosphorus in the continental runoff of dissolved and solid substances were systematized and generalized, with a separate consideration of the processes of runoff transformation in river mouth areas. It has been established that atmospheric deposition, which many authors consider to be an important source of phosphorus in river runoff and not associated with mobilization processes in catchments, actually contains phosphorus from soil-plant recycling. This is confirmed by the fact that the input of phosphorus from the atmosphere into catchments exceeds its removal via water runoff. An analysis of the mass ratio of phosphorus in the adsorbed form and in the form of its own minerals was carried out. It was shown that the maximum mass of adsorbed phosphorus is limited by the solubility of its most stable minerals. The minimum concentrations of dissolved mineral and total phosphorus were observed in the rivers of the Arctic and subarctic belts; the maximum concentrations were confined to the most densely populated temperate zone and the zone of dry tropics and subtropics. In the waters of the primary hydrographic network, the phosphorus concentration exhibited direct relationships with the population density in the catchments and the mineralization of the river water and was closely correlated with the nitrogen content. This strongly suggests that economic activity is one of the main factors in the formation of river phosphorus runoff. The generalization of the authors’ and the literature’s data on the behavior of phosphorus at the river–sea mixing zone made it possible to draw a conclusion about the nonconservative distribution of phosphorus, in most cases associated with biological production and destruction processes. The conservative behavior of phosphorus was observed only in heavily polluted river mouths with abnormally high concentrations of this element.
  • 451
  • 07 Jan 2022
Topic Review
Peralkaline Granitic Rocks
The Lower Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska hosts a high-grade uranium-thorium deposit with past production. The complex is a circular body (~3 km in diameter) which intruded Paleozoic granitoids as well as metasedimentary and metavolcanic rocks of the Alexander Terrane of the North American Cordillera.
  • 260
  • 18 Aug 2023
Topic Review
Particle-Bound Mercury Characterization
Particulate Bound Hg (PBM) consists of all airborne particulate containing Hg, including both stable condensed and gaseous forms adsorbed on atmospheric particulate matter (PM); it is operationally sampled and quantified by pulling air through a glass fiber or a quartz filter. PBM usually includes all those particles with a diameter <2.5 μm, even if its characterization depends on the pore size of the filter used for its collection. The accurate dimensional characterization is then essential to estimate the dry deposition of PBM, as well as any other particulate pollutant; the particles diameters directly influence gravitational sedimentation and the PBM residence time in the atmosphere. In addition, PBM chemical speciation, as well as for the other Hg forms, is fundamental to understand PBM bioavailability and therefore the effects on human .
  • 1.0K
  • 05 Jul 2021
Topic Review
Organic Matter in Forming Gold-Deposits
Carbonaceous organic matter occurs under various phases and forms, where its fine characterization is mostly restricted to petroleum and coal geology. As a consequence, few studies have integrated the complete link between various forms of organic matter and metals to decipher hydrothermal ore concentrating processes. The study of Dill et al., integrating the concentration of sulfides and oxides with the interaction of silicates and organic matters, is an example of the next step to reach for defining the complex role of organic matter for the formation of orogenic gold deposits.
  • 1.3K
  • 27 Aug 2021
Topic Review
Multi-Element Imaging of the 1.4Ga Authigenic Siderite Crystal
The Al- and Fe-enriched zone in the core of siderite crystal might be an iron-bearing nucleus, and the formation of rim structure was related to the transition from a closed crystallization environment to a semi-closed growth environment. These results, combined with carbon isotope evidence from the siderites and surrounding shales, suggest that vigorous dissimilatory iron reduction that can provide Fe2+ and HCO3− to the pore water is a key factor to form the siderite-dominated Xiamaling IF.
  • 444
  • 21 Dec 2021
Topic Review
Mineralizing Fluids at Porphyry Deposits of Cu−Mo−Au System
The porphyry type of hydrothermal mineral deposits is of paramount economic importance because deposits of this type host much of the world’s reserves of Cu, Mo, and Re, as well as much Re and remarkable reserves of critical elements such as Ag, Pd, Te, Se, Bi, Zn, and Pb. Porphyry deposits are conventionally classified into mineralogical–geochemical types according to their dominant valuable components. The most economically important porphyry-type deposits are those of the Cu (Au), Cu–Mo (Au), Mo, and Au types.
  • 730
  • 05 May 2022
Topic Review
Microbially Induced Carbonate Precipitation
 Microbially induced carbonate precipitation (MICP) is a promising technology for solidifying sandy soil, ground improvement, repairing concrete cracks, and remediation of polluted land. By solidifying sand into soil capable of growing shrubs, MICP can facilitate peak and neutralization of CO2 emissions because each square meter of shrub can absorb 253.1 grams of CO2 per year.
  • 808
  • 01 Dec 2021
Topic Review
Microbial Mats: Extraterrestrial Life Models
Extant microbial mats already present on Earth provide useful working analog models for the exploration of life in extraterrestrial hydrospheres.
  • 1.0K
  • 08 Sep 2021
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