The influence of the ratio between soil weight and solution volume (soil/solution ratio) on a distribution coefficient of cesium for coastal sandy soil, kaoline and silica sand to water has been studied. The distribution coefficients of ¹³⁷Cs for the soils decreased with the increase of the soil/solution ratios. The concentration of the cations dissolved from the soils into the solution varied with the soil/solution ratio. However, when the concentration of coexistent cations kept to be 10^–2 mol/l, the distribution coefficient was kept constant at different soil/solution ratios. These results show that the soil/solution ratio does not directly affect on the adsorption of ¹³⁷Cs on the soils, but the variation in the concentration of dissolved cations with the soil/solution ratio results in the change in the distribution coefficient.

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Oxygen isotope ratios of phenocrysts separated from a rhyolite of San Vincenzo, Italy, were measured using the laser-probe technique. The phenocrysts (<3 mm diameter of alkali-feldspar, plagioclase, and quartz) were picked from a 0.5 to 1 mm thick section mounted on an adhesive tape. One to 2 mg samples were used for oxygen isotope analysis, while the major element chemistry of a small portion separated from the same phenocryst was determined by electron microprobe. The accuracy and reproducibility of the oxygen isotopic ratio (measurement error ±0.2‰) and chemical composition obtained for each separated phenocryst are comparable to those of conventional stable isotopic and chemical analyses. The δ¹⁸O values of the feldspars range from +11.7 to 14.6‰ (SMOW), while those of the quartz ranges from +13.8 to 14.4‰. The δ¹⁸O values of the feldspars decrease with increasing Or component. The large variation of oxygen isotope ratios may be attributed to oxygen isotopic heterogeneity of the source magma during crystallization, caused by magma mixing and assimilation.

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Spatial distribution of δD and δ¹⁸O values of surface water and shallow groundwaters from Japan, south Korea and east China was mapped with contours of 10 and 1‰ intervals for δD and δ¹⁸O, respectively, on the basis of the data base including more than 600 analyses made in the present and previous studies. The δD and δ¹⁸O values generally decrease with increasing the latitude. There is a systematic decrease in δD and δ¹⁸O values with contours of close intervals from the coast toward inland of southwestern Japan along the stream of the Kuroshio, a warm current in the Pacific Ocean. The δD and δ¹⁸O lows are observed in mountainous inland of central and northern Japan and east China. The trends are comparable with those observed previously for the North American continent. The map will provide fundamental information for the studies of geochemical processes such as hydrology, water-rock interaction, and precipitation of authigenic minerals in which meteoric water is involved.

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Physical chemical characteristics of the Solnechnoye tin deposit hydrothermal system have been studied. Ores of cassiterite-tourmaline type was formed in a vertically dipping fracture zone, extended up to 8 km in a metamorphosed mass of sandstone-shale rocks. This rock mass transfers in its root part to a granitoid massif (quartz diorites-monzonites). The evolution in composition of the mineral-forming solution was studied by gas-chromatographic analysis of gaseous phase of fluid inclusions. The analysis of aqueous extracts from fluid inclusions (AAS, potentiometry, ICP and ionic chromatography) was also performed. It was found that as the process proceeded from the preore quartz-tourmaline stage to productive quartz-cassiterite, the values of a_HCO-3, a_(SII), CO₂/CH₄, HCO₃/Cl and pH increased. The value of f_O2 corresponded to the F-Q-M buffer on the preore stage and increased up to that of the Ni-NiO buffer during the formation of the main part of cassiterite ores. Study of organic compounds showed that a greater degree of oxidation in comparison to the preore stage is typical for the quartz-cassiterite and the main sulfide stages. It means that organic compounds participated in redox reactions which took place in the solutions during the precipitation of these mineral assemblages. The δ¹⁸O values of fluids calculated from the δ¹⁸O values obtained for the minerals show a distinct trend of decrease toward later stages. The δD values for the waters from the inclusions are close to those found for contemporary meteoric waters (–120‰). A transport model of non-isothermal isotope exchange between water and arbitrary number of minerals along the fluid flow paths was used for the interpretation of these isotope data as well as of the data on the isotope composition of the wall-rocks. Descending flow of meteoric waters was found to interact with sandstone-shale rocks and with granitoids before entering into the discharge zone. Comparison of the chemical and isotopic data which characterize the evolution of the mineral forming environment of the Solnechnoye tin deposit allows us to conclude that mixing of acid, reducing, high temperature solutions, genetically related to granitoid melt, with alkaline-excessive, more oxidized, less saline meteoric waters, which have undergone interaction with wall rocks and granitoids, is the necessary condition for the redox reactions, resulting in cassiterite ore formation.

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