Investigation of shocked materials provides unique information about behavior of substances in extreme thermodynamic conditions. Near surface nuclear tests have induced multiple transformations of affected soils. Examination of nuclear glasses and relics of entrapped minerals provides a unique database on their behavior under an intense temperature flash. In this work, several types of nuclear fallout particles from historic tests at the Semipalatinsk test site are investigated using complementary analytical methods. Distribution of radionuclides in all types of samples is highly heterogeneous; domains with high content of radionuclides are often intermixed with non-active materials. There is no general correlation between chemical composition of the glassy matrix and content of radionuclides. In aerodynamic fallout, the main fraction of radionuclides is trapped in the outer glassy shell. Relics of quartz grains are always devoid of radionuclides, while glass regions of high activity have different composition. In contrast to underground tests, iron-rich minerals are not necessarily radioactive. In most cases, the glassy matrix in anhydrous and is strongly polymerized, and the Q3 silicate groups dominate. Temperature-induced transformations of entrapped minerals are discussed. Investigation of zircon grains shows absence of a direct correlation between degree of decomposition into constituting oxides, morphology of resulting baddeleyite, and maximum experienced temperature. For the first time, temperature history of a nuclear ground glass is estimated from Zr diffusion profiles from decomposing zircon grain.
Sorption of actinides, particularly plutonium, onto submicrometer-sized colloids increases their mobility, but these plutonium colloids are difficult to detect in the far-field. We identified actinides on colloids in the groundwater from the Mayak Production Association, Urals, Russia; at the source, the plutonium activity is approximately 1000 becquerels per liter. Plutonium activities are still 0.16 becquerels per liter at a distance of 3 kilometers, where 70 to 90 mole percent of the plutonium is sorbed onto colloids, confirming that colloids are responsible for the long-distance transport of plutonium. Nano-secondary ion mass spectrometry elemental maps reveal that amorphous iron oxide colloids adsorb Pu(IV) hydroxides or carbonates along with uranium carbonates.
Peter the Great Bay and Lake Khanka are among the most important structural and industrial fishing parts of the Far East coastal ecosystem, which are used by a number of countries such as Russia, China, Korea, Japan, etc. At the same time, the active use of water resources, as well as industrial activities deployed on the coastal part of these reservoirs, are accompanied by a constant flow of pollutants into the water area. Among them, one can include heavy metals; their entry and migration are currently not fully controlled. There exists an important scientific and ecological task to study the features of heavy metal migration and transformation in natural objects. Bottom sediments act as a substrate for hydrobionts and, at the same time, serve as accumulators of pollutants, so that they can be used as the main component of the coastal-shelf ecosystem. The geochemical assessment of the behavior of heavy metals in the bottom sediments of Ussuri Bay and Amur Bay (Sea of Japan) and Lake Khanka (Xingkai) has been performed. Qualitative and quantitative elemental compositions of the bottom sediments have been established by means of the inductively coupled plasma-mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS), and X-ray fluorescence analysis (XRF), whereas a correlation with the concentration of elements in seawater above sediments has been provided. The main phases of anthropogenic components as well as their relationship with an increased content of heavy metals have been established using X-ray diffraction analysis (XRD). Average values of the concentration of elements in the bottom sediments of Peter the Great Bay decrease in the following row: Fe > Cu > Cr > Zn ≥ Pb > Mn > Ni, and for Lake Khanka: Pb > Cu > Mn > Fe > Cr > Zn > Ni. Here, the excessive contents of Cr, Fe, Cu, Zn, and Pb in sea bottom sediments by 6, 32, 7, 3, and 4 times as compared with background values are the result of the formation of a large amount of carbonate and iron-oxide phases. At the same time, it was shown that, during the transition from the estuarine (coastal) area of river flow to the central (closer to the outlet to the ocean), the concentration of biogenic metals (Ni, Zn, Pb, Cu) generally decreased 2–4-fold along the profile, which was associated with the formation of their hydroxides and carbonates in the area of mixing of freshwater and seawater followed by that of complex compounds or absorption. A significant anthropogenic impact is observed in the lake sediments, which is demonstrated by the excess of Pb concentration by 6700 times, as compared with the Clarke number of the lithosphere. The non-uniform distribution of heavy metals along the core profile has been established, which is related to different contents of aluminosilicate and iron oxide phases in the form of hematite and magnetite. The sedimentation rate has been established by means of granulometric and radiometric analysis and equaled to 0.45 mm/year in Ussuri Bay, 1.6 mm/year in Amur Bay, and 0.43–0.50 mm/year in Lake Khanka. By calculating the distribution coefficients of heavy metals in the ‘water–deposits’ system, some features of migration and accumulation of individual elements have been established. To assess the potential pollution of the marine areas, the geoaccumulation index (Igeo) and the pollution factor (Kc) have been calculated. In comparison with the maximum permissible concentrations of the Russian Federation (MPC), the World Health Organization (WHO), the US Environmental Protection Agency (US EPA), and environmental protection agencies of China and Japan, Peter the Great Bay has an excess of Mn—2-fold, Fe—2-fold, Zn—3-fold, whereas in Lake Khanka, the situation is even less favorable, in particular, the excess of Mn is 79-fold, Fe—35-fold, Cu—2-fold, Zn—3–4-fold, which is clearly determined by the closeness of the water basin and the lack of water exchange. In comparison with the lithosphere Clarke number, the sediments of both water basins, as well as the coastal soil of the lake, are enriched with Pb and depleted with Cr, Ni, and Zn. The highest values of Igeo in both water basins have been observed for Pb, and equaled 12–16 in Peter the Great Bay and 6000 in Khanka Lake. Based on the data obtained, the areas with the greatest pollution caused by natural and anthropogenic factors have been identified.
Uranium oxide microparticles ingestion is one of the potential sources of internal radiation doses to the humans at accidental or undesirable releases of radioactive materials. It is important to predict the obtained dose and possible biological effect of these microparticles by studying uranium oxides transformations in case of their ingestion or inhalation. Using a combination of methods, a complex examination of structural changes of uranium oxides in the range from UO2 to U4O9, U3O8 and UO3 as well as before and after exposure of uranium oxides in simulated biological fluids: gastro-intestinal and lung-was carried out. Oxides were thoroughly characterized by Raman and XAFS spectroscopy. It was determined that the duration of expose has more influence on all oxides transformations. The greatest changes occurred in U4O9, that transformed into U4O9-y. UO2.05 and U3O8 structures became more ordered and UO3 did not undergo significant transformation.
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