The Japanese Association of Groundwater Hydrology (JAGH) celebrated its 60th anniversary in 2019. For the last 10 years, research and business activities have been conducted while exploring the social role and activities to be performed as a public interest incorporated association. In this article, after looking back on research and business activities over the past 10 years, it was shown how the research and business activities of JAGH should proceed for the next 10 years from a perspective industry-government-academia collaboration.

Groundwater discharge in alpine headwaters sustains baseflow in rivers originating in worldʼs mountain ranges, which is critically important for aquatic habitats, run-of-river hydropower generation, and downstream water supply. Groundwater storage in alpine watersheds was long considered negligible, but recent field-based studies have shown that talus, moraine, and rock-glacier aquifers are common in many alpine regions of the world, although bedrock aquifers occur in some geological settings. Spatial extent and distribution of individual aquifers determine the groundwater storage-discharge characteristics in first- and second-order watersheds in the alpine zone, which in turn govern the baseflow characteristics of major rivers. Similar alpine landforms appear to have similar hydrogeological characteristics around the world, suggesting that a common conceptual framework can be used to understand alpine aquifers based on geological and geomorphological settings. Such a framework will be useful for parameterizing storage-discharge characteristics in large river hydrological models.

Gasoline is a typical substance in the soil pollution with petroleum hydrocarbons. In this study, focusing on hydrocarbons of methane series (alkanes: n-pentane ~ n-dodecane) which are main constituents of gasoline, the acute toxicity tests were carried out. The difference in the acute toxic effect on luminous bacteria due to the variation in the carbon number of the alkanes was assessed.

In the tests on 100 vol％of the alkanes without methanol solvent, the acute toxicity of the alkanes could not be clearly assessed since the bacteria might not absorb the alkanes which were hydrophobic. On the other hand, in the tests on the alkanes dissolved in methanol solvent, significant results could be obtained. The higher the carbon number of alkane and also the higher the concentration, the longer it took for the relative luminescence intensity ratio to reach a constant value. Regardless of the species of alkane, overall, the relative luminescence intensity ratio became lower as the alkane concentration became higher. The effects of the alkane concentration on the relative luminescence intensity ratio tended to be strongly in the alkanes with lower carbon number than alkanes with higher carbon number. This was presumed that reaction rate for the acute toxicity effect on the luminous bacteria becomes lower as the carbon number of the alkanes becomes higher. Therefore, when performing the acute toxicity evaluation for the alkanes under the test conditions in this study, the data at a reaction times of 60 minutes will be desirable to use rather than those at 30 minutes. Also, this study indicated that the results of the acute toxicity evaluation for the substances, such as gasoline, consisting of mixed

Arsenite-arsenate separation analysis technique using a commercial anion exchange resin column with quaternary ammonium cations as anion exchange groups was studied. The selection of the optimum conditions for the valence-dependent separation of inorganic arsenic and the influence of coexisting anions were examined experimentally. By calculation based on the first dissociation constants of arsenite and arsenate, the optimum pH range of the test solution for valence separation of arsenic was estimated to be 4.3 to 7.1. When the test solution adjusted to the above pH was passed through the column, the arsenic in the test solution was separated appropriately by valence, because the arsenite is not adsorbed and the arsenate is adsorbed on the resin. Also, the arsenate adsorbed on the resin could be easily recovered almost completely by using HCl or HNO₃. The strength of the inhibition effect of coexisting anions on the recovery of arsenic was clarified to be “CH₃COO^－ << Cl^－ < NO₃^－ < SO₄^2－”. The arsenite-arsenate separation analysis technique proposed in this study separated and recovered arsenite and arsenate with an experimental error of about 6％under the experimental conditions.