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101.
Toshihiko Ohnuki Takahiro Yoshida Takuo Ozaki Mohamad Samadfam Naofumi Kozai Kunio Yubuta Toshiaki Mitsugashira Takeshi Kasama Arokiasamy J. Francis 《Chemical Geology》2005,220(3-4):237-243
We assessed the accumulation of uranium (VI) by a bacterium, Bacillus subtilis, suspended in a slurry of kaolinite clay, to elucidate the role of microbes on the mobility of U(VI). Various mixtures of bacteria and the koalinite were exposed to solutions of 8 × 10− 6 M- and 4 × 10− 4 M-U(VI) in 0.01 M NaCl at pH 4.7. After 48 h, the mixtures were separated from the solutions by centrifugation, and treated with a 1 M CH3COOK for 24 h to determine the associations of U within the mixture. The mixture exposed to 4 × 10− 4 M U was analyzed by transmission electron microscope (TEM) equipped with EDS. The accumulation of U by the mixture increased with an increase in the amount of B. subtilis cells present at both U concentrations. Treatment of kaolinite with CH3COOK, removed approximately 80% of the associated uranium. However, in the presence of B. subtilis the amount of U removed was much less. TEM–EDS analysis confirmed that most of the U removed from solution was associated with B. subtilis. XANES analysis of the oxidation state of uranium associated with B. subtilis, kaolinite, and with the mixture containing both revealed that it was present as U(VI). These results suggest that the bacteria have a higher affinity for U than the kaolinite clay mineral under the experimental conditions tested, and that they can immobilize significant amount of uranium. 相似文献
102.
Abstract. Chemical and sulfur isotopic compositions were obtained for a series of rocks within the chert‐clastic sequence surrounding the Kajika massive sulfide ore horizon at Shibukawasawa in the Ashio copper‐mining district, Ashio Terrane, central Japan. The sequence is lithologically classified into three units: chert, siliceous shale with basic volcanics, and sandstone‐shale, in ascending stratigraphic order. The Kajika ore horizon corresponds to the lowermost part of the unit that contains siliceous shale with basic volcanics. The rocks around the Kajika ore horizon are enriched in P2O5 (max. 0.22 %), Ba (max. 2400 ppm), Cu (595 ppm), V (323 ppm), Pb (168 ppm), Zn (124 ppm), and Mo (24 ppm) in siliceous shale; and Ba (4220 ppm), Zr (974 ppm), Cr (718 ppm), Ni (492 ppm), V (362 ppm), Zn (232 ppm), Nb (231 ppm), and Co (71 ppm) in the basic volcanics. The siliceous shale is enriched in a number of redox‐sensitive elements such as Cu, V, Pb, Zn, and Mo, which are known to be enriched in black shale and anoxic and hydrothermal sediments. The δ34S values of sulfides in the chert and sandstone‐shale lie in the range of 0±2 %, and those in the siliceous shale range from ‐5 to ‐14 %. The measured δ34S values in the basic volcanics are ‐0.3, ‐2.7, and ‐31.5 %. These heavier δ34S signatures (around 0 %) recorded throughout the sequence indicate that the rocks formed under anoxic bottom‐water conditions. Slightly lighter δ34S values recorded in siliceous shale might reflect significant mixing of sulfides that formed by sulfate‐reducing bacteria in an overlying oxic environment. The long‐term duration of anoxic conditions indicated by the heavier δ34S signature is considered to have played an important role in protecting the Kajika sulfide ores from oxidative decomposition and preserving the ores in sedimentary accumulations. 相似文献
103.
Abstract ' In situ basalts' represent the ridge magmatism at and close to the ancient trench-trench-ridge triple junction. Such basalts in the Amami, Mugi, and Setogawa accretionary complexes, Southwest Japan, were described and analysed. The geochemical data show that the ' in situ basalts' include all the types of basalts, ranging from alkali basalts and high-alumina basalts to tholeiites, and the compositions tend towards intermediate and silicic rocks. The data also reveal that the ridge basalts are indistinguishable both from the island arc and intraplate basalts, no affinities with mid-ocean-ridge basalts. The sub-ridge mantle adjacent to the triple junction had a component of sub-arc mantle, and this mantle heterogeneity can be generated by the formation of a slab window. 相似文献
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Naoki Yoshida † Ravi K. Sheth Antonaldo Diaferio 《Monthly notices of the Royal Astronomical Society》2001,328(2):669-677
We use numerical simulations of a (480 Mpc h −1 )3 volume to show that the distribution of peak heights in maps of the temperature fluctuations from the kinematic and thermal Sunyaev–Zeldovich (SZ) effects will be highly non-Gaussian, and very different from the peak-height distribution of a Gaussian random field. We then show that it is a good approximation to assume that each peak in either SZ effect is associated with one and only one dark matter halo. This allows us to use our knowledge of the properties of haloes to estimate the peak-height distributions. At fixed optical depth, the distribution of peak heights resulting from the kinematic effect is Gaussian, with a width that is approximately proportional to the optical depth; the non-Gaussianity comes from summing over a range of optical depths. The optical depth is an increasing function of halo mass and the distribution of halo speeds is Gaussian, with a dispersion that is approximately independent of halo mass. This means that observations of the kinematic effect can be used to put constraints on how the abundance of massive clusters evolves, and on the evolution of cluster velocities. The non-Gaussianity of the thermal effect, on the other hand, comes primarily from the fact that, on average, the effect is larger in more massive haloes, and the distribution of halo masses is highly non-Gaussian. We also show that because haloes of the same mass may have a range of density and velocity dispersion profiles, the relation between halo mass and the amplitude of the thermal effect is not deterministic, but has some scatter. 相似文献
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110.
The distribution of inorganic nitrogen compounds and the metabolic rates of these compounds by microorganisms as a whole were investigated in the Seas of Hiuchi and Bingo. The results obtained are as follows:
- Of inorganic nitrogen compounds, the contents in sea water, those in bottom muds, the uptake or liberation rates of microorganisms as a whole in sea water, and the liberation rates from bottom muds to sea water are 0.2~4.0 μg at. N/l, 3~60 μg at.N/100 g, 0.01~0.5 μg at.N//lhr, and 0.3~1.9 μg at.N/100 cm2/hr, respectively, and these contents or rates of ammonia usually are the largest of these inorganic nitrogen compounds.
- From the above-mentioned results and the others, it is suggested that the nitrogen in the seas circulates mainly in sea water itself and the course of nitrogen cycle, which passes through bottom muds, is not so important, and further that, of the cycle of inorganic nitrogen compounds, the main course is the course which ammonia is liberated from organic nitrogen compounds and it is immediately uptaked by microorganisms, and the course which it is oxidized to nitrate and the others are not so important.