Abstracts of Annual Meeting of the Geochemical Society of Japan

Allan Hills 84001, a unique Martian meteorite, shows extremely old crystallization age and complicated shock metamorphic history. While igneous phosphate minerals are volumetrically minor, they concentrate trace elements in the magma and give various information. Phosphates contain U and Th, and has been used for U-Th-Pb dating. In this study, we determine U-Pb age of phosphates in ALH 84001 from measurements of single-grain with size of 50-100 micron, using NanoSIMS. From obtained distributions of U and Pb within a grain, the thermal history of the meteorite can be estimated.

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In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid-leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their p-process isotopic abundances leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of p-process isotopes, ⁸⁴Sr, ¹³⁰Ba, ¹³²Ba, ¹³⁶Ce, ¹³⁸Ce, and ¹⁴⁴Sm were observed, particularly in the first chemical separate。

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Monthly measurements (January - May, 2013) of reactive oxygen species (ROS), which include H₂O₂, NO and OH radicals in Kurose river of Higashi-Hiroshima, Japan were carried out. Water samples were collected at six different locations (upstream to downstream) of the river. H₂O₂ concentrations were analyzed via Fenton reaction. NO and .OH were measured using 4,5-diaminofluorescein-2 (DAF-2) and benzene as probes, respectively. Range of mean values showed that H2O2 concentrations were from 94-172 nM, while those of NO and .OH photoformation rates(x 10^-10 Ms^-1) were from 0.03?14.81 and 0.06?6.36, respectively. Lifetimes of NO and .OH were 0.11-0.49 s and 0.39-5.84 ?s, respectively. Steady-state concentrations of NO and .OH were 0.01?3.66 (x 10^-10 M) and 0.52?27.46 (x 10^-16 M), respectively. There was a strong correlation (r² = 0.933) between NO photoformation rates and the [NO₂^-] present in the river, suggesting the anion as the major NO precursor; also, >70% of the photoformed .OH was contributed by the NO₂^-.

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The presence of pesticide residues in surface water bodies is one of the most important environmental concerns. Pesticides include Fenitrothion (O,O-Dimethyl O-(3-methyl-4-nitrophenyl phosphorothioate), Diuron (3-[3,4-dichlorophenyl]-1,1-dimethylurea) and Irgarol (2-[tert-butylamino]-4-[cyclopropylamino]-6-[methylthio]-1,3,5-triazine). Diuron, Irgarol and Fenitrothion are toxic to reef building (hermatypic) corals, non-target algae and wide variety of aquatic organisms respectively hence the need for their continuous monitoring. In this study, water samples were collected from Kurose River in Higashi-Hiroshima at monthly intervals. Pesticide extraction was by Solid Phase Extraction (SPE) and analysis by an HPLC system equipped with a UV-Vis detector (SPD-10A, Shimadzu). Sampling points from upstream to downstream were Namitakiji, Tokumasakami, Izumi, Ochiya, Hinotsume and Kurosebunka Centre. The pesticide ranges were; Diuron (not detected (n.d) - 4620ng/L), Irgarol (n.d - 50ng/L) and Fenitrothion (n.d - 310ng/L). Diuron levels were highest in May (Time rice fields are prepared for planting). Fenitrothion levels were highest in April (Attributed to use in rice nursery beds). Irgarol levels (Only detected at Izumi - Midstream of Kurose River) were highest in May but lower than Diuron (Attributed to the fact that Irgarol sources are protective paints for structures and not rice fields). Results compare well with study by Sakugawa et al., (2010), who found highest levels of Diuron at Misonou (An area very close to Izumi). Fenitrothion and Irgarol results also compared well with other studies done in same area.

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