open access

https://hdl.handle.net/2115/44893

Geochemical studies on submarine groundwater discharges in Toyama Bay using methane as a tracer

日本語

Toyama Bay

2005-08-20

日本地球化学会

Chikyukagaku (Geochemistry)

39(3)

131-140

We present here a geochemical study on the SGD in the Toyama Bay using CH4 and its carbon isotope ratio as tracers. We found that all SGD fluids and many of land groundwaters contain less methane than natural water in equilibrium with atmospheric CH4. Theδ13C values of CH4 in the SGD fluids range from -50 to -20‰ VPDB, almost comparable or slightly higher than that of atmospheric CH4. The results suggest that most of methane in the SGD fluids had been derived from the atmosphere and a part of the CH4 is oxidized in the course of groundwater flow through the aquifer, with no CH4 production that is usual in highly anoxic groundwater.This is probably due to little organic matter content in the aquifer and/or a short residence time from recharge to discharge on seafloor. The low concentration and high carbon isotopic ratio of CH4 are similar to those in some of the land groundwaters. The SGD fluid in Uozu should be flowing underground along the Katagai River.

学術雑誌論文

Version of Record

0386-4073

AN00141280