Microbial DNA. A brand-new tracer of groundwater flow

To understanding better how the groundwater flow passes and its influence on the water chemistry we employ a brand-new method to analyze microbes with abundance and community constituents transported by groundwater. In the previous studies, estimation of transit time and groundwater flow path by groundwater flow analysis, estimation of averaged residence time of groundwater by chemical analysis such as various radioactive elements and stable isotopes have been widely used in hydrological studies. These methods show an averaged value of chemistry of the investigated water which was blended by various water with different sources and flow passes in subsurface environment. In order to improve the reliability of the estimation of the transport of groundwater, we focus on microbes in particular Microbial DNA. Particles represent the place from which they were transported. Transported microbes express the environment being appropriate for their growth. Interaction among rocks - groundwater - microorganisms is studied to evaluate biogeochemical influences on natural barrier of geological disposal facility for high-level-radioactive wastes. This study shows the possibility to reveal the groundwater history such as groundwater flow and the environment from which groundwater flow through analyzing the density of prokaryotes and microbial community structure analysis. (author)