Revisiting Mt Fuji’s groundwater origins with helium, vanadium and environmental DNA tracers

Abstract

Known locally as the water mountain, for millennia Japan’s iconic Mt Fuji has provided safe drinking water to millions of people via a vast network of groundwater and freshwater springs. Groundwater, which is recharged at high elevations, flows down Fuji’s flanks within three basaltic aquifers, ultimately forming countless pristine freshwater springs among Fuji’s foothills. Here we challenge the current conceptual model of Fuji being a simple system of laminar groundwater flow with little to no vertical exchange between its three aquifers. This model contrasts strongly with Fuji’s extreme tectonic instability due to its unique location on top of the only known continental trench–trench–trench triple junction, its complex geology and its unusual microbial spring water communities. On the basis of a unique combination of microbial environmental DNA, vanadium and helium tracers, we provide evidence for prevailing deep circulation and a previously unknown deep groundwater contribution to Fuji’s freshwater springs. The most substantial deep groundwater upwelling has been found along Japan’s most tectonically active region, the Fujikawa-kako Fault Zone. Our findings broaden the hydrogeological understanding of Fuji and demonstrate the vast potential of combining environmental DNA, on-site noble gas and trace element analyses for groundwater science.

Vanadium in the Environment: Biogeochemistry and Bioremediation

“…207,208 Abundant metal elements in terrestrial systems flow into the ocean through the air−soil−river pathway, 209 including V, with endogenous sources in the ocean. Consequently, oceans are the main sinks of V. 210,211 The V/Ca record in a Porites coral colony collected in an offshore nonestuarine island of the northern South China Sea indicates that it remarkably captures the temporal patterns of anthropogenic activities. 212 Vanadium bromoperoxidase is an abundant and robust enzyme found in all classes of marine algae that catalyzes the oxidation of halides.…”

Editorial: Advances and emerging methods in tracer hydrogeology

“…Owing to recent advances in both analytical and numerical techniques and methods, the information that we are now able to gain from hydrological tracers-both artificial and naturalhas become much more interdisciplinary, precise, and spatially and temporally resolved (Tetzlaff et al, 2015;Brunner et al, 2017;Benischke, 2021;Schilling et al, 2023). The articles in this Research Topic eloquently illustrate the capacity of emerging gas tracer techniques to provide valuable quantitative knowledge about hydrological processes, including the connectivity of surface and subsurface water resources.…”