In order to examine possible formation of organics in slightly reducing primitive atmospheres, mixtures of N₂，CH₄，CO₂ and H₂O were irradiated with high-energy protons or UV light, or were subjected to spark discharges, and amino acids and carboxylic acids in the products were determined. While UV and spark discharges did not yielded amino acids if the molar ratio of CH4 was less than 10%, amino acid precursors gave amino acids even if it was as low as 0.5%. Carboxylic acids were formed by spark discharges or proton irradiation even when no methane was added. It has been reported that young solar-type stars occur superflares. It was suggested that major energy sources for production of amino acids in the primitive Earth atmosphere was extraterrestrial high-energy particles such as galactic cosmic rays and/or solar energetic particles.

At this talk, the speaker presents the results of field studies in the Kyusyu/Okinawa region for the elucidation of secondary organic aerosol (SOA) in the real atmosphere. In the studies the semi-real time measurements using aerosol mass spectrometry and offline analysis for concentration and stable carbon isotope ratio of low-volatile water soluble organic carbon (LV-WSOC) were performed. The resutls demonstrated a high correlation between the strength of a fragment ion from carboxylic acid and the concentration of LV-WSOC. Data analysis suggested that the carboxlic acid and LV-WSOC are likely SOA origin. Furthermore, the analysis implied that the LV-WSOC also contained some extent of LV-WSCO from an unknown different origin.

Carbonates are common minerals through geologic time, and carbonate geochronology provides time constraints on evolutional history of organisms, paleoenvironmental changes, tectonic events, and subsurface fluid-flow changes. Application of in situ U-Pb dating method to carbonates has been limited by the lack of carbonate reference materials with homogeneous U and Pb concentrations and isotopic compositions. In this study, we tried to synthesize a new calcite reference material with homogeneous elemental and isotopic compositions. The calcites were synthesized by heating amorphous calcium carbonates precipitated with a dopant solution containing U, Pb, and rare earth elements with known Pb isotopic composition. The elemental and isotopic homogeneity of the synthetic calcite was evaluated using laser ablation inductively coupled plasma mass spectrometry.

Radiocarbon (14C) has been widely used in determining the age of various geological materials and events. The validity of ages, particularly for sediments, has often been questioned due to the incorporation of carbon-bearing components with different abundances of 13C and 14C. For the purpose of isolating various carbon sources in sediment, a procedure is adopted in this study including 1) size fractionation before regular sample pretreatment and 2) temperature stepped-combustion in place of conventional high temperature oxidation. Then, this procedure was applied on terrace sediments from two study areas at western Taiwan.The first step in this study was to carry out a radiocarbon study of sediment samples collected from Nanfu terrace in western Taiwan. Humic acids (HA) and humins were extracted from the very fine and coarse grain-size fractions of sediment using a standard acid-base-acid (ABA) pretreatment. The humin extracts were combusted at 400 and 1100 °C by stepped-combustion, to yield a low-temperature (LT) carbon component and a high-temperature (HT) carbon component. A consistent relationship can be observed by comparing the ages of the LT and HT humin fractions to the HA fractions of samples collected at 2 depths within the Nanfu terrace profile. The HA ages are the youngest on average, and overlap with the LT ages, and the carbon contained in the HT fraction is always distinctly older than both the LT and HA ages. To better understand the relationship between 14C age and combustion temperature, incremental stepped-combustion experiments were conducted with one of the samples (1E) using 50 °C steps that ranged from 300°C to 1100 °C. The 14C results of the stepped-combustion products show a clear division between 2 isotopically identifiable carbon constituents, from carbon released below 400 °C and carbon released above 550°C. By comparing the δ13C and 14C results, a third carbon isotopic component is identified in the humin that is released when combusted at ~500°C.Since organic matter is mainly bound to clay minerals in fine sediments, the next phase of this study was to focus on carbon contained in clays. The same temperature stepped-combustion procedure was applied to well-crystalized clay minerals (kaolinite, illite and illite-smectite) in a series of experiments ranging from 350°C to 1100°C. Distinct carbon components were identified in the samples using both their 13C and 14C contents. Two carbon end-members were observed for all of the clay minerals: a low temperature component (＜400°C), relatively depleted in 13C and enriched in 14C; and a high temperature component (＞550°C), relatively enriched in 13C and depleted in 14C. The high temperature carbon component is relatively old and not released until the clay is completely oxidized. This observation suggests that this carbon was incorporated into the clay mineral when it first formed by weathering.The same procedure was applied to field sediments collected from terraces along the Kueichung River, in southwestern Taiwan, sieved to ＜64 μm. The results from sediments are similar to the well-crystallized clay minerals, with distinct low temperature (relatively young) and high temperature (relatively old) end members. One of the sediments also contained a third carbon component, possibly detrital carbon. The radiocarbon dates on these various carbon fractions provide a range of dates enabling us to place constraints on the timing of terrace development in Taiwan.The procedure used in this study successfully separates carbon sources in terrace sediments. Organic carbon bound on minerals is well accepted in previous researches, but this study is the first to provide 14C ages of distinct carbon sources from organo-mineral complex. It implies by this procedure radiocarbon dating technique can be applied on any kind of sediment, and its age interpretation will be varied based on the binding mechanism.

Here we propose a highly-sensitive quantitative approach to determine ultra-trace rare earth elements (REEs) profiles in intact stalagmite samples, allowing the identification and localization of anomalies caused for example by volcanic eruptions. The approach combines a highly sensitive sector field ICPMS with a laser sampling approach in open atmosphere followed by gas exchange for sample introduction. The use of a “jet” vacuum interface and the addition of small amounts of N2 gas allowed for a 20-40 fold sensitivity enhancement compared to the conventional interface configuration. Mass load effects, quantification capabilities and detection power were investigated in analyses of reference materials using various combinations of spot sizes and laser repetition rates. From 160 µm diameter circular laser spots and 10 Hz ablation frequency, limits of detection were in the low or sub-ng g-1 range for REEs. Relative deviations of quantified concentrations from USGS MACS-3 preferred values were smaller than 12%. The analytical approach enabled the determination of REE concentration profiles at the single digit ng g-1 level. This well-characterized open-cell LA-ICPMS methodology gives the potential to apply to other natural carbonates, such as travertine, tufa, and flowstones, for providing a better comprehension of earth and environmental sciences.

The multi-decadal variability of North Atlantic Oscillation (NAO), which has been reported as a driver of modern rapid climate change, pronouncedly made an impact on Europe climate in the past one century. However, lack of longer, continuous, and high-resolved plaeoclimate record hampers our understanding of the rate of the NAO phase change and its responses to the external/internal forcing especially on multi-annual to multi-decadal time scales. We present a multi-annually resolved precipitation record from the northern Mediterranean region over the past 6,500 years. This record and our simulations indicate insolation-induced millennial non-stationary behaviors of the NAO. The revealed irregularly-spaced hydroclimatic fluctuations with multidecadal-to-multicentennial wet/dry events and rapid shifts within a few decades, especially over the last 3 thousand years, are strongly coupled with tropical Pacific thermal conditions. Our results provide hints of potentially more frequent rapid climate change in Atlantic region in the future.

Perchlorate (ClO4-) is of growing concern due to its widespread occurrence on Earth and Mars, as well as potential adverse effect for human beings. In recent, the discovery of ClO4- on Mars has prompted a renewed interest in the formation and preservation of ClO4- in arid and semi-arid deserts on Earth, because the desert could serve as a viable analog for Martian landscape. In this study, we investigated the concentration of Cl-, ClO4-, and NO3- anions in sand, river sediment, moraine, and loess samples collected from the Taklimakan Desert, Xinjiang, NW China by ion chromatograph (IC). Furthermore, the speciation of Cl was determined for selected samples by the bulk XANES and μ-XRF-XRD-XANES techniques. The aims of this study are (i) to clarify the distribution of ClO4- in different types of samples and its possible formation mechanisms; (ii) to provide direct spectroscopic evidences for the presence of ClO4- in the sample; (iii) to provide insights into the prevalence of ClO4- on Mars. The moraine samples generally contain much higher concentrations of ClO4- in comparison with other samples investigated; which suggests that ClO4- could be readily preserved by the moraine resulting from its lack of liquid water. A weaker correlation between NO3- and ClO4- and the low ratios of NO3-/ClO4- were observed in the samples, possibly implying that atmospheric deposition of ClO4- produced by photochemical reaction in the atmosphere is not the only source for ClO4- in the samples from the Taklimakan Desert. These results were further confirmed by the Cl μ–XANES analyses showing different ratios of ClO4- in different interested points in the moraine sample.

Lithology and climate exert a major influence on weathering processes. The complete understanding of weathering processes necessitates a deeper study of inter-relationships of lithology-climate-weathering. In the present study, an attempt has been made to understand the role of climate and source-rock mineralogy in the formation of clay minerals during weathering of granites along an east-west climatic transect of northern India. The Aravalli craton (west), Bundelkhand craton (centre) and Singhbhum craton (east) provided an ideal condition to carry out this study as they are characterised by arid, semi-arid and sub-humid climate, respectively. Analysis of primary minerals present in the least altered granite rocks was carried out using thin section petrography, X-ray diffraction (XRD) technique and normative calculation. Clay mineralogy of weathering profiles along the climatic transect was studied using XRD. In the Aravalli craton, 2:1 clay (smectite, characteristic of the poorly drained environment) was dominant. Illite, interstratified smectite-kaolinite and kaolinite were found only in trace amounts. In the Bundelkhand craton, smectite, illite and kaolinite were dominant with some amount of interstratified smectite-kaolinite minerals and mixed layers (10-14 Å). On the other hand, in the weathering profiles of the Singhbhum craton 2:1 clay (illite) and 1:1 clay (kaolinite) were dominant clay minerals with significant peaks of mixed layer clays as well as interstratified smectite-kaolinite minerals. Interstratified smectite-kaolinite minerals characterised by tailing in the low angle region of kaolinite (7.2 Å) peak are an important ephemeral stage during the transformation of smectite to kaolinite in humid climates. Presence of interstratified smectite-kaolinite minerals is also suggestive of advancement of in situ weathering in the weathering profile. The data generated on clay mineralogy was analysed in the light of primary minerals present in granite of each area, and it was found that the rainfall plays a dominant role in the formation of clay minerals as compared to source-rock mineralogy.

we measured concentration of reactive oxygen species in waters of 8 rivers located in Kanto District to Kyushu District, Japan. Steady state concentration, photochemical formation rate and half-life were determined. Peroxides such as hydrogen peroxide and lipid peroxides were also measured. Soureces and sinks of the reactive oxygen spceis in river water were elucidated and discussed about their roles in mineralization and redox reactions of dissoled organic matter.

River water samples were collected from Chiba prefecture to Fukuoka prefecture and the concentration of hydrogen peroxide was measured. The measurement of hydrogen peroxide was performed by HPLC-fluorescence detection method.As a result, the concentration in the river water was several tens to several hundreds nM, the highest and lowest concentrations were observed in the Yamato River (Osaka prefecture + Nara prefecture) and the Ota River (Hiroshima prefecture), respectively.The regression analysis revealed that the dissolved organic carbon concentration and the combination of solar radiation and water temperature mainly determined the hydrogen peroxide concentration.

The steady state concentrations of singlet oxygen and hydroxyl radicals in the Seto Inland Sea were measured.The steady state concentration of singlet oxygen was around 10-14 M, which was four orders of magnitude higher than the hydroxyl radical. The singlet oxygen concentration was strongly correlated with the concentration of dissolved organic matter.The rate of reaction between these active oxygen species and pesticides such as diazinon and methylmercury was analyzed and the rate of decomposition in sea water was estimated.

It is known that superoxide (O2·−) and nitric oxide (NO ·) are photochemically generated in sea water. Although it was predicted that peroxynitrite (ONOO-) is formed from these two radicals, there were no empirical evidence of its presence in seawater. We developed a fluorescence analytical method for photochemical ONOO- in this study, and succeeded in measuring its concentration in seawater of Seto Inland Sea. The results revealed that ONOO- exists at steady-state concentrations of several pM in seawater of the Seto Inland Sea.

Pesticides are primarily used in agricultural fields to control weeds, insects and fungal pests. This study conducted risk assessment of pesticide residues in Kurose River in Higashi-Hiroshima city, Japan. Water samples were analysed for cyanazine, simetryn, fenarimol and isoprothiolane and diazinon monthly for one year (Mar. 2016 – Feb. 2017) using HPLC. Ecotoxicological risk assessment was done based on Risk Quotient (RQ) index while non-carcinogenic risk for humans were estimated by hazard quotient (HQ). The study revealed fairly high RQ ＞1 for diazinon, consistent with reports elsewhere. However, all the pesticides posed insignificant human health risk (HQ ＜ 1).