Abstract:The Kara ore node is located within the Sretensk-Kara ore region of East Transbaikalia. The geological structure of this area is complex due to its location within the Mongol-Okhotsk suture, the zone wherein the Siberian and Mongolia-China continents collided into each other at the turn of the Early and Middle Jurassic. During the plate collision, intense magmatism was accompanied by the formation of focal-dome, dome-ring and other structures. The Kara ore node is controlled by the Ust-Kara focal dome-ring structure. The central part of latter is composed of KaraChacha granitoids from the Amudzhikan-Sretensk intrusive complex (J3-K1) with the system of subvolcanic and vein formations, including grorudites. It is suggested that gold mineralization in the study area is genetically related to grorudites; however, physical and chemical conditions for the formation of these alkaline rocks, their genesis and role in the hydrothermal gold-ore process still have not been sufficiently investigated. To this end, the authors of this paper have studied fluid inclusions (FI) in quartz from these rocks. It has been found that quartz porphyry phenocrysts in grorudite contain FI of diverse forms, the size of which ranges from 5 to 48 microns. Measured temperatures of ice melting (-2.5°C) and complete homogenization into liquid (350 °C) show that the concentration of salts in the fluid amounts to 4.2 wt % of eq. NaC, its density is 0.64 g/cm 3 , and the pressure is 1.6 kb. At LA-ICP-MS of individual FI, clear analytical signals were derived from Na and K. As, Mo, Sb, Cs, W, and Hg were traced in significant quantities. The Raman scanning showed the presence of N2 in the primary (substantially gaseous) FI, and CO2, N2, and CH4 in the primary-secondary FI.
The rapidly increasing production of engineered nanoparticles has raised questions regarding their environmental impact and their mobility to overcome biological important barriers. Nanoparticles were found to cross different mammalian barriers, which is summarized under the term translocation. The present work investigates the uptake and translocation of cerium dioxide nanoparticles into maize plants as one of the major agricultural crops. Nanoparticles were exposed either as aerosol or as suspension. Our study demonstrates that 50 microgram cerium per gram leaves was either adsorbed or incorporated into maize leaves. This amount could not be removed by a washing step and did not depend on closed or open stomata investigated under dark and light exposure conditions. However, no translocation into newly grown leaves was found when cultivating the maize plants after airborne particle exposure. The use of inductively coupled mass spectrometer allowed detection limits of less than 1 nanogram cerium per gram leaf. Exposure of plants to well characterized nanoparticle suspensions in the irrigation water resulted also in no detectable translocation. These findings may indicate that the biological barriers of plants are more resistant against nanoparticle translocation than mammalian barriers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.