Twenty-six groundwater samples were collected From Tanegashima, Yakushima, and Nakanoshima islands between July 27 and August 2, 2003. The interpretation of chemical analyses suggested that the groundwater on the islands have been affected by sea salt (ss). Chlorine (Cl^-) concentrations on Yakushima, which were inversely related to elevation, were considerably lower than those on Nakanoshima and Tanegashima, reflecting higher annual rainfall on Yakushima. However, groundwater samples from Yakushima had a higher ratio of ss components—more than 50% (except one sample). Non-sea salt (nss) components of the groundwater on Tanegashima, Yakushima, and Nakanoshima were found to be affected mostly by the chemical weathering of plagioclase feldspars. The groundwater on Tanegashima was also thought to be affected by ion exchange between clay minerals and Ca²⁺. The effects of sulfuric acid and carbonic acid on chemical weathering were nearly equivalent on Nakanoshima. Therefore, the average concentrations of nssSO₄^2- and dissolved SiO₂ were remarkably higher than those for Yakushima and Tanegashima. The arithmetic mean concentration of nssK⁺ on Yakushima was high even though the total concentration of all nss components was low. The nssK⁺ probably originates from chemical weathering of K-feldspar in granite. The total concentration of nss components on Yakushima was remarkably lower than that on Tanegashima or Nakanoshima. Low NO₃^--N concentrations in these mountainous and forested islands reflect a low load from anthropogenic activities.

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北海道幌延町において，堆積岩を対象とした深地層の研究施設を利用して，地上からの地球化学調査技術の妥当性を検証した。また，地下施設建設が周辺の地球化学状態に及ぼす影響について考察した。地上からのボーリング調査について，調査数量と水質深度分布の予測向上の関係を整理した結果，3本程度の基本ボーリング調査と断層・割れ目帯など高透水性の水理地質構造を対象とした追加ボーリング調査により，数キロメータースケールの調査解析断面の水質分布について不確実性も含めて評価できることが明らかになった。地下施設建設に伴う地下水の塩分濃度，pH，酸化還元状態の擾乱を観察した結果，一部の高透水性地質構造の周辺において，地下坑道への湧水による水圧や塩分濃度の変化が確認された。この変化量は事前の予測解析結果と整合的であった。これらの成果は，他の堆積岩地域における地上からのボーリング調査や地下施設建設時の地球化学調査の計画監理にも参照可能と考えられる。

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