地球化学
Online ISSN : 2188-5923
Print ISSN : 0386-4073
ISSN-L : 0386-4073
52 巻, 3 号
選択された号の論文の2件中1~2を表示しています
2017年度日本地球化学会賞受賞記念論文
  • 角皆 潤
    2018 年 52 巻 3 号 p. 107-129
    発行日: 2018/09/25
    公開日: 2018/09/25
    ジャーナル フリー

    By using the hydrogen isotope exchange equilibrium between molecular hydrogen (H2) and water vapor, a new method called HIReTS (Hydrogen Isotopes Remote Temperature Sensing) was proposed for remote sensing of fumarole outlet temperatures. In this method, the hydrogen isotopic composition (δD) of fumarolic H2 is obtained remotely from observation in a volcanic plume, and the outlet temperature is then derived from the obtained δD of fumarolic H2. The HIReTS method can be used to obtain the fumarolic temperature remotely in active volcanoes when the actual fumaroles are inaccessible. Recent advances in using the 17O-excess (Δ17O) of nitrate were summarized as well. Within the possible sources of nitrate in the natural environment, only atmospheric nitrate that is produced from atmospheric NO through photochemical reactions can be characterized by the anomalous enrichment in 17O, reflecting the transfer of an oxygen atom from ozone. In addition, Δ17O is stable during partial metabolism—such as denitrification and assimilation, so by using these characteristics of Δ17O, the author and co-workers were able to trace the fate of atmospheric nitrate deposited onto surface ecosystems. This also allowed the author and co-workers to propose a new method to quantify nitrate dynamics—production rate through nitrification and metabolic rate through assimilation and denitrification—in aquatic environments, using the Δ17O of nitrate. The Δ17O method is considered to offer an alternative to the traditional artificial tracer techniques for the determination of nitrate dynamics, including temporal variations.

2017年度日本地球化学会奨励賞受賞記念論文
  • 吉村 寿紘
    2018 年 52 巻 3 号 p. 131-142
    発行日: 2018/09/25
    公開日: 2018/09/25
    ジャーナル フリー

    Major cations (Na, Mg, K and Ca) are essential for life and play a major role in the global geochemical cycles. Dissolved cations in terrestrial waters derive from both silicate and carbonate rocks, and rivers and groundwater deliver them to the ocean, where there is a steady-state balance between inputs and outputs over geological time. Calcium carbonates are central components in understanding the chemical budgets of major cations for modern and past oceans. Biogenic CaCO3 is an important tool for elucidating the oceanic chemical evolution and past climate changes. Recent advances in mass spectroscopy techniques have made it possible to explore the stable isotope system of Mg, Ca, K and Sr in geologic materials, each of which are novel indicator for constraining the interplay of natural systems in the geological past; continental weathering, carbonate budgets, mid-ocean ridge spreading rates, etc.

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