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The global Calcium (Ca) cycle is closely coupled to the carbon cycle, and Ca isotopes have potential in tracing it. Even though groundwater is one of the main reservoirs of Ca at the Earth's surface, few data are available for groundwater, and the behavior of Ca and its isotopes in geothermal systems remains unknown. Here we analysed the stable Ca and radiogenic Sr isotope compositions of thermal waters distributed along the Jinsha and Yalong river valleys in the southeastern Tibetan Plateau. The Ca isotopic composition of the thermal water ranges from 0.45 to 2.16 ‰ (δCa values relative to SRM 915a). The thermal waters collected from carbonate aquifers have higher δCa values than bedrocks, which was attributed to secondary carbonate precipitation accompanied by CO degassing. In contrast, δCa values in thermal waters collected from clastic and igneous rocks are similar to bedrock. Despite some thermal waters undergoing secondary silicates formation and CaNa ion exchange, such processes maybe not play a significant role in governing the Ca isotopic composition of these thermal waters. This suggests that Ca isotopes can be used to trace secondary carbonate precipitation driven by CO degassing (e.g. travertine) in geothermal systems located in tectonically active areas.
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http://dx.doi.org/10.1016/j.scitotenv.2023.161534 | DOI Listing |
Nature
September 2025
Natural History Sciences, IIL, Hokkaido University, Sapporo, Japan.
Carbonaceous asteroids are the source of the most primitive meteorites and represent leftover planetesimals that formed from ice and dust in the outer Solar System and may have delivered volatiles to the terrestrial planets. Understanding the aqueous activity of asteroids is key to deciphering their thermal, chemical and orbital evolution, with implications for the origin of water on the terrestrial planets. Analyses of the objects, in particular pristine samples returned from asteroid Ryugu, have provided detailed information on fluid-rock interactions within a few million years after parent-body formation.
View Article and Find Full Text PDFPhysiol Rep
September 2025
Department of Sports Medicine, Japan Institute of Sports Sciences, Kita-ku, Tokyo, Japan.
Among the different forms of hydrotherapy, carbon dioxide (CO) water immersion improves peripheral vasodilation and blood flow compared with tap water immersion; however, the heat stress placed on the body through CO water immersion and the appropriate immersion protocols are uncertain. Therefore, this study aimed to compare the thermoregulatory responses during CO and tap water immersions. The participants were 10 male college baseball players.
View Article and Find Full Text PDFMethods Cell Biol
September 2025
Área de Microbiología, Departamento de Biología Funcional, Facultad de Medicina, IUBA, Universidad de Oviedo, Oviedo, Spain. Electronic address:
The present study focuses on the phenotypic characterization of several mutants of Flavobacterium psychrophilum, obtained from a transposon mutant library. This Gram-negative bacterium is the etiological agent of the "cold water disease", pathology that usually affects salmonids, mainly Oncorhynchus mykiss. This microorganism is considered a "fastidious bacterium" due to the difficulty to isolate it.
View Article and Find Full Text PDFInt J Biol Macromol
September 2025
School of Materials Science and Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China. Electronic address:
Efficient water-absorbing and water-holding materials have shown notable promise in various applications, including hygiene products, agriculture, and drug delivery systems. Opposed to traditional absorbents prepared using synthetic polymers, bio-based, environmentally friendly efficient absorbents have attracted more attention from both academia and the industry. Herein, the aerogel absorbents from functional sodium carboxymethyl cellulose (CMCNa), citric acid (CA) crosslinker, and cellulose nanofibers (CNF) have been developed via freeze-drying and cross-linking process.
View Article and Find Full Text PDFWater Res
September 2025
State Key Laboratory of Geomicrobiology and Environmental Changes, Hubei Key Laboratory of Critical Zone Evolution, China University of Geosciences (Wuhan), Wuhan 430078, China; Hubei Key Laboratory of Marine Geological Resource, China University of Geosciences, Wuhan 430074, China. Electronic addre
Anthropogenic climate warming and coastal eutrophication have restructured phytoplankton communities in the East China Sea; however, the centennial-scale dynamics of phytoplankton remain poorly understood. By systematically integrating 33 sediment cores, we reconcile the variations of primary productivity during the last century. The results revealed increased primary productivity during the past century, while the phytoplankton groups showed divergent eco-regional responses: river-dominated estuaries have partially mitigated the dominance of dinoflagellates (1980s) via Changjiang nitrate loading, while potential hypoxic regions shifted earlier (1960s) under thermal forcing and silicate concentration.
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