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Iriomote Island, the Ryukyus, is easy to receive the effect by the long-distance transportation of acid substances from the Eurasian Continent and Taiwan, since the island is close to these areas. The average pH of the precipitation on the island was 4.7. The values of pH(H₂O) and pH(KCl) were measured in order to examine the effect of the acid deposition on the island. The soil with lower pH(KCl) values showed the smaller ion-exchange capacity. In the watershed which widely distributes siliceous sandstone, the acid buffer capacity by HCO₃^- in river water is small, and the effects of the acid deposition may be remarkable.

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The hydrogen isotopic (D/H) fractionation factors between the crystal water of crystalline hydrates and the saturated aqueous solutions of divalent transition metal (cobalt, nickel and copper) dichloride and between the aqueous solutions and their vapor were experimentally determined under equilibrium condition. The crystal water of these crystalline hydrates exhibits larger depletion of deuterium than the saturated aqueous solutions. And the water vapor equilibrated with these aqueous solutions exhibits larger enrichment of deuterium than the water vapor equilibarated with pure water. These facts indicate that the hydration complex is depleted in deuterium.

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Liquid scintillation counting with electrolysis enrichment is now the most popular method to measure the tritium concentration in the low level water samples such as environmental water samples. It takes, however, much time and a lot of doings, but it has not a sufficient accuracy. We have sophisticated all of the procedure, using a conventional electrolysis enriching apparatus and a conventional liquid-scintillation counter. As the result, we have achieved the detection limit of 0.02 Bq/L in 2 days enrichment and 25 hours counting. Furthermore, we considered the possibility to lower the detection limit and we were able to prospect to measure until 0.0005 Bq/L, starting from 1 L sample water, in 1 week enrichment and 1 week counting.

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The study on terrestrial carbonates such as speleothem and tufa deposits has shown that important information can be extracted using the sulfate contents in them. The concentration of sulfate ion coprecipitated in the carbonates is directly proportional to the concentration of sulfate of the mother liquid. In this study, the distribution constants of sulfate were estimated for stalactites and tufa.

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Aluminum and iron rich red soils distribute widely over the Ryukyu Islands. The origin of the red soils has been considered as residual deposit of Ryukyu Limestones. However, the origin of the red soils is still debated into two possibilities; one is residual deposit of parent base rock, Quaternary and Paleozoic limestones (Ryukyu Limestones), and the other is long range transported aeolian dust from Inland Asia.

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Biogenic calcium carbonates (e.g. coral skeleton, foraminifera and bivalve shell) have been widely used as proxies for past changes in sea water temperature because elemental composition (Sr/Ca and Mg/Ca ratio) of their skeletons are believed to vary quantitatively as a function of the ambient seawater temperature. However, recent studies using micro-analytical technique have revealed that there is a large chemical heterogeneity in their skeleton, which cannot be explained by the temperature variation. To reconstruct the past climate accurately, it is essential to understand the mechanism of elemental fractionation in biogenic calcium carbonate.

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This is the first report of the supersensitive and effective detection of alkaline cryptotephras by instrumental neutron activation analysis (INAA). Cryptotephra are tephra horizons that are invisible to the naked eye. The Ta/Sc elemental ratio of glass shard in a tephra known to be from an alkaline volcano is reported as ca. 15, whereas the average Ta/Sc value in typical sediments is below 0.1. We detect two unknown alkaline cryptotephras, which were not detected by susceptibility measurements, from down-core profiles of the Ta/Sc ratio in a piston core from Lake Biwa in Japan. The Th/Sc ratio is a useful indicator for verifying the absence of interference by Ta-rich heavy mineral. Two or three alkaline cryptotephras are also found from annually laminated sediment in a drilled core from Lake Suigetsu in Japan, and are correlated with those from Lake Biwa.

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The event of Ulleung Oki (U-Oki) tephra, distributed across the southwestern Japan sea, originated in an explosive eruption of alkali magma from the caldera in Ulleung island in the Japan sea. However, it is suggested that some unknown alkaline ash fall events, which are probably from the Ulleung island, had occurred besides U-Oki tephra between AT and K-Ah. The Ta/Sc ratio in the alkaline tephra from continental volcano has significantly different characteristics with the general tephra erupted by island arc volcanism. We have already carried out INAA determination of 12 trace elements from five cores in the southwest Japan Sea. The analysis of these cores had revealed some peaks in the vertical distribution of Ta / Sc ratio in the upper and lower parts of U-Oki layer, as well as the strong peak at U-Oki layer. We also detected K-Ah cryptotephra layer by the ratio of other trace elements from four cores. We are going to confirm it with using EPMA.

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In the present contribution, we reconstruct the marine Os isotopic composition over the past 500 ky from the metalliferous carbonates of the ODP Site 834 in the Lau Basin. The marine 187Os/188Os ratios are estimated to range from 0.824 to 0.991. There is no distinct difference in 187Os/188Os ratios between glacial and interglacial periods. Based on box model calculations, we estimate that the riverine Os flux at LGM was ~40 % of the present riverine Os flux. This decrease in riverine Os flux may have been caused by the decrease in riverine water flux due to cold and arid climate at LGM.

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We measured Raman spectra of 7 mole percent LiCl (NaCl, KCl, CsCl) bearing solution at 23 degree C. A possible transition from low-pressure water to high-pressure water previously seen in pure water was not observed in these solutions. Implications to aqueous fluids in the Earth and planetary interior will be addressed.

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We will be presenting our Os isotope data obtained for the organic-rich sediments including the Selli Level (OAE1) from the Umbria-Marche region in Central Italy, representing an almost complete sequence covering the period before, during, and after the main pulse of Ontong Java Plateau volcanism. Our initial results suggest a lowering of seawater Os isotope composition from a "background" value of ~0.67 around chron M0r (125-124.61 Ma), suggesting a significant input of Os from the mantle with low 187Os/188Os.

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Lanthanide tetrad effects are seen in the standard-state enthalpy data for a variety of Ln(III) compound or complex series. The tetrad effects can be inverted into the relative values of Racah (E1 and E3) parameters on the basis of RSPET equation. Systematic decrease of Racah parameters (the nephelauxetic series) determined from the thermochemical data is compatible with the spectroscopic results.

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Cr diffusion was determined in enstatite and used to develop thermochronologic formulations of Mn-Cr system. The latter was used to estimate high temperature cooling rates and initial burial depth of a pallasite and cumulate eucrites.

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Chlorine is one of mobile and trace elements and has affinity with fluids. Due to terrestrial contamination and heterogenuiety, the detailed distributions of chlorine in chondrites have not been well established yet. We report here results of critical evaluation of chlorine distributions in chondrites, based on search on literature data, analyses of chondrites and textural examinations.

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Oxygen in CAIs in primitive chondrites generally shows mass-independent isotopic fractionation. The self-shielding of CO has been proposed for this anomalous O-isotope. This process necessarily suggests that the CAI oxygen must be the same as the solar oxygen, and the planetary oxygen differ from the solar oxygen. With Bootstrap statistical examination of meteorite data, we show that the planetary oxygen must be the same as the solar oxygen, and hence the self-shielding hypothesis cannot be warranted.

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