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Compound specific radiocarbon analysis of individual fatty acids were carried out for the semi-urban aerosol samples in Chinese loess (Kosa) season. fatty acid distribution shows a bimodal pattern with the maxima at C₁₆ and C₂₄. d¹³C values of fatty acids ranged from -31 to -21 per mil, suggesting that the long chain fatty acids is derived from terrestial higher plants. D¹⁴C values of individual fatty acids ranged from -97 to +123 per mil, which shows that the longer fatty acids are older values. We estimate that the fatty acid contribution by Kosa is 10-20% in the aerosol in this Kosa season.

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Atmospheric transport of particles from land to ocean has been often evaluated from the biomarkers of terrestrial higher plant waxes as long-chain alkanes, fatty alcohols and acids. However, there were a few studies on (paleo)climatological and atmosphere chemical investigations from higher plant terpenoids (HPTs), which were peculiar biomarkers of higher plants with structural variety. In this study, HPTs were analyzed in deep sea sediments off central and northern Japan to reconstruct the historical variations of the transport fluxes of terrestrial materials, and to examine their applicability as proxies for assessing the eolian transport of terrestrial particles to ocean.

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The set of REE partition coefficients between Cpx and silicate melt was the one starting point of the "araurunium" project. Here is presented a new view of the partition coefficients, and its modern significance will be discussed.

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Astrobiogeochemistry of transition metal stable isotopes has been rapidly growing. Because of occurrences of large isotope fractionations associated with biological processes and minimal isotope fractionations during high temperature-pressure metamorphisms, transition metal stable isotopes have a potential to be used as a tool to detect biological activity and trace past biogeochemical cycles of the elements. Its overview and future perspective will be given in the talk.

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Pb isotopic chronometer can serve as a valuable tool in unraveling the history of the early solar system not only because it can provide us with the absolute age of the planetary materials but also because it can, upon meeting certain requirements, determine the age of planetary materials with an uncertainty of few million years or less. In this talk, I would like to introduce some of my recent work on the Pb isotopic systematics of chondritic meteorites, and discuss about possible future which this work may lead to.

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Dynamics and chemical nature of fluorescent dissolved organic matter (FDOM) were investigated in two river waters. DOC monthly and temporarily varied in the two river waters. The FDOM in the river waters identified three characteristic fluorescence peaks, indicating the occurrence of fulvic acids (peak F), fluorescent whitening agents (peak W), and protein-like substances (peak T). The FDOM in upstream and Ohta downstream contained the peaks F and T whereas Kurose downstream waters contained the peaks W and T. The ratio of fluorescence intensity for peak F or W with DOC (FI/DOC-index), diurnal variations and photo irradiation experiments for FDOM indicated that the chemical properties of FDOM in the Kurose downstream are different with those in the Kurose upstream and Ohta river waters.

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Tangential flow ultrafiltration (TFF) was applied to separation of high molecular weight organic matter (HMW-DOM, MW>1kD) dissolved in freshwaters. Tens to hundreds mg of HMW-DOM were separated from 80-100 l of waters in yields of 30-70% of total DOC. In a eutrophic lake, stable isotope ratios of C and N tend to be heavier than those in meso to dystrophic lake waters. The C/N atomic ratio is low in the eutrophic lake. Both parameters appear to indicate that thte productivity within the lake should reflect also on tne nature of HMW-DOM. On the contrary, lipid analyses showed that C29 stigmasterol is the major sterol associated with this size of DOM.

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Recently, natural occurrence arsenic pollution in groundwater has been reported from various areas of the world. In this study, we target the largest polluted area, Bangladesh. Sonargaon area located on 25km south east of Dhaka is affected the significant arsenic pollution. We sampled groundwater from there in rainy and dry season, and analyzed the chemical and isotopic compositions. Based on those chemical characteristics, we investigate the formation mechanism of arsenic polluted groundwater, and also refer the seasonal variation.

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The ancient city of Palmyra lies on a large oasis located in the center of the Syrian Desert. The skeletal remains uncovered from the underground tombs of Palmyra retain traces of osteoporosis and mottled enamel, implying that ancient people of Palmyra suffered fluorosis. Using chemical analysis data of the 13 natural waters available today in this area, the concentration of F^- ions contained in the drinking water, used by the ancient people of Palmyra who suffered fluorosis, were estimated to be 3 ppm on the basis of chemical equilibrium calculation relating to the fluorite dissolution. The analytical data on the F^- concentration of teeth of the ancient people of Palmyra will also be discussed.

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Nitrogen isotope ratios in ground and river waters from Shogawa fan were measured. Delta15N in ground water was 3-4 per mil. Nitrogen in ground water was regarded to be derived from fertilizer spreaded over paddy field in Shogawa fan. Delta15N in Sho River was -2 to -1 permill, thus nitrogen in Sho R. was natural origin. Oyabe River showed delta15N change from -2 (headwaters) to 4 (downstream). This suggests the inflow of irrigation water from paddy field and sewage water in Oyabe River Basin.

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For the extraction of environmental information, absolute dating of sample must be done. As a result of measurements of samples using fluorescence microscopy, it has been clarified that the stalagmite samples obtained from Akiyoshi-dai and Hirao-dai Plateau have fluorescent microbanding with respective average thickness of 26.4 µm and 23.8 µm. The thickness of the layers of a tufa sample from Akiyoshi-dai was 0.5 mm, and that of a tufa sample from Hirao-dai was ranged from 0.1 to 2 mm. The main fluorofore was found to be fulvic acid both for the stalagmite and tufa samples. In case of the Hirao-dai tufa sample, the measurements of the 137Cs g-ray activity were also carried out, and the 137Cs peaks due to the 1945 and the early 60s were detected.

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