Groundwater geochemical study at the Mizunami Underground Research Laboratory; Development of groundwater filtration techniques while maintaining in-situ hydrochemical conditions

Aosai, Daisuke; Yoshida, Haruo*; Mizuno, Takashi   

In this report, we summarize filtration techniques developed and employed at the Underground Research Laboratory. The methods are useful for the physical and chemical characterization of minute particles in contaminated groundwater (including organic and inorganic particles, microbes, etc.), which can effect migration behavior. It is also useful for investigating the adsorption and complexation of particles and elements in groundwater. We performed the filtration of groundwater on site while maintaining in situ pressure and anaerobic conditions and in the laboratory under controlled anaerobic conditions. The results indicate the viability of groundwater filtration under in situ geochemical conditions, if the filtration is performed at controlled pressure and anaerobic conditions and with strict quality control. However, sample contamination occurs if stainless steel equipment is used. Therefore, to avoid contamination, we intend to develop Teflon equipment.