EGU General Assembly 2022
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Temporal evolution of dissolved gases in groundwater of Tenerife Island

Cecilia Amonte1,2, Nemesio M. Pérez1,2, Gladys V. Melián1,2, María Asensio-Ramos1, Eleazar Padrón1,2, Pedro A. Hernández1,2, and Ana Meire Feijoo1
Cecilia Amonte et al.
  • 1Instituto Volcanológico de Canarias (INVOLCAN), 38320 San Cristóbal de La Laguna, Tenerife, Canary Islands (
  • 2Instituto Tecnológico y de Energías Renovables (ITER), 38600 Granadilla de Abona, Tenerife, Canary Islands

The oceanic active volcanic island of Tenerife (2,034 km2) is the largest of the Canarian archipelago. There are more than 1,000 galleries (horizontal drillings) in the island, which are used for groundwater exploitation and allow reaching the aquifer at different depths and elevations. This work presents the first extensive study on the temporal variation of dissolved gases in groundwaters from Fuente del Valle and San Fernando galleries (Tenerife, Spain) since April 2016 to June 2020. This investigation is focused on the chemical and isotopic content of several dissolved gas species (CO2, He, O2, N2 and CH4) present in the groundwaters and its relationship with the seismic activity registered in the island. The results show CO2 as the major dissolved gas specie in the groundwater from both galleries presenting a mean value of 260 cm3STP·L-1 and 69 cm3STP·L-1 for Fuente del Valle and San Fernando, respectively. The average δ13C-CO2 data (-3.9‰ for Fuente del Valle and -6.4‰ for San Fernando) suggest a clear endogenous origin as result of interaction of them with deep-origin fluid. A bubbling gas sample from Fuente del Valle gallery was analysed, obtaining a CO2 rich gas (87 Vol.%) with a considerable He enrichment (7.3 ppm). The isotopic data of both components in the bubbling gas support the results obtained in the dissolved gases, showing an endogenous component that could be affected by the different activity of the hydrothermal system. During the study period, an important seismic swarm occurred on October 2, 2016, followed by an increase of the seismic activity in and around Tenerife. After this event, important geochemical variations were registered in the dissolved gas species, such as dissolved CO2 and He content and the CO2/O2, He/CO2, He/N2 and CH4/CO2 ratios. These findings suggest an injection of fluids into the hydrothermal system during October 2016, a fact that evidences the connection between the groundwaters and the hydrothermal system. The present work demonstrates the importance of dissolved gases studies in groundwater for volcanic surveillance.

How to cite: Amonte, C., Pérez, N. M., Melián, G. V., Asensio-Ramos, M., Padrón, E., Hernández, P. A., and Meire Feijoo, A.: Temporal evolution of dissolved gases in groundwater of Tenerife Island, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8458,, 2022.