chemia: Thorium

Evidence: 49 • authority: 72

Uranium (92U) is a naturally occurring radioactive element (radioelement) with no stable isotopes. It has two primordial isotopes, uranium-238 and uranium-235, that have long half-lives and are found in appreciable quantity in Earth's crust. The decay product uranium-234 is also found. Other isotopes such as uranium-233 have been produced in breeder reactors. In addition to isotopes found in nature or nuclear reactors, many isotopes with far shorter half-lives have been produced, ranging from 214U to 242U (except for 220U). The standard atomic weight of natural uranium is 238.02891(3). Natural uranium consists of three main isotopes, 238U (99.2739–99.2752% natural abundance), 235U (0.7198–0…

Evidence: 43 • authority: 92

Revealing the Earth's mantle from the tallest mountains using the Jinping Neutrino Experiment.. The Earth's engine is driven by unknown proportions of primordial energy and heat produced in radioactive decay. Unfortunately, competing models of Earth's composition reveal an order of magnitude uncertainty in the amount of radiogenic power driving mantle dynamics. Recent measurements of the Earth's flux of geoneutrinos, electron antineutrinos from terrestrial natural radioactivity, reveal the amount of uranium and thorium in the Earth and set limits on the residual proportion of primordial energy. Comparison of the flux measured at large underground neutrino experiments with geologically infor…

Evidence: 43 • authority: 80

Uranium, thorium, and rare-earth elements in Alaska

Evidence: 43 • authority: 72

The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%).

Evidence: 37 • authority: 92

⁶Li-loaded directionally sensitive anti-neutrino detector for possible geo-neutrinographic imaging applications.. Despite the latent and unique benefits of imaging uranium and thorium's distribution in the earth's interior, previously proposed experimental techniques used to identify the incoming geo-neutrino's direction are not applicable to practical imaging due to the high miss-identification in a neutrino's track reconstruction. After performing experimental studies and Monte-Carlo simulations, we confirmed that a significant improvement is possible in neutrino tracking identification with a (6)Li-loaded neutrino detector. For possible imaging applications, we also explore the feasibili…

Evidence: 37 • authority: 92

Contrasting Rare Earth Element Signatures Between Stromatolitic Carbonates and Lagoon Waters at Shark Bay, Western Australia: Implications for Paleo-Environmental Reconstructions of Microbial Habitats.. Rare earth elements and yttrium (REY) signatures in stromatolitic carbonates have emerged as powerful geochemical proxies for reconstructing paleo-depositional environments of microbial habitats. The applicability of such a proxy relies on the assumption that REY substitutes for calcium into crystal lattices, directly reflecting the composition of the fluid from which the carbonate precipitated. The REY signatures of stromatolites are often similar to those of open ocean seawater. In restric…

Evidence: 37 • authority: 72

The actinide () or actinoid () series encompasses at least the 14 metallic chemical elements in the 5f series, with atomic numbers from 89 to 102, actinium through to nobelium. Number 103, lawrencium, is also generally included despite being part of the 6d transition series. The actinide series derives its name from the first element in the series, actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. The 1985 IUPAC Red Book recommends that actinoid be used rather than actinide, since the suffix -ide normally indicates a negative ion. However, owing to widespread current use, actinide is still allowed. Actinium through nobel…

Evidence: 37 • authority: 80

Heat flow studies: Constraints on the distribution of uranium, thorium and potassium in the continental crust

Evidence: 37 • authority: 80

Migration of mantle-derived uranium and thorium within the crust

Evidence: 37 • authority: 80

Mechanisms of uranium and thorium transfer to the crust

Evidence: 37 • authority: 92

Records of mantle geodynamics and atmospheric escape in Archean quartz.. Early planetary degassing and atmospheric escape are two major, yet unconstrained, processes that shaped early Earth. Modeling predicts that the atmospheric 20 Ne/ 22 Ne ratio is sensitive to solar-Ne mantle degassing over geological time. Until the Great Oxidation Event, atmospheric escape progressively depletes the atmosphere in Xe, leaving an isotopic imprint. However, the quantity of xenon in the ancient atmosphere remains largely unknown. In this study, we analyzed noble gases in Archean hydrothermal quartz fluid inclusions and show that a modern atmospheric 20 Ne/ 22 Ne ratio was almost reached 2.7 Ga ago, implyi…

Evidence: 37 • authority: 92

Thorium Valorization at the Interface of Technology, Risk, and Sustainability.. Thorium (Th), a naturally occurring actinide, is gaining renewed attention due to its dual role as a strategic nuclear resource and a potential environmental contaminant. This review critically reassesses thorium valorization pathways by integrating extraction technologies, environmental behavior, toxicological risks, and regulatory constraints. While thorium is primarily recovered as a by-product of rare earth element (REE) processing, conventional hydrometallurgical methods-though mature-generate significant secondary waste and pose environmental challenges. Emerging technologies, such as functionalized adsorb…