Recharge and source‐water insights from the Galapagos Islands using noble gases and stable isotopes

A novel approach using noble gases and stable isotopes reveals distinct recharge patterns in the Galápagos Islands' fractured basaltic aquifers. The study, conducted on Santa Cruz and San Cristóbal islands, demonstrates that low-altitude springs (<420 m) and basal aquifer samples are primarily recharged during the hot season, while high-altitude springs (>420 m) show recharge from both the garúa (cooler) and hot seasons. Noble gas temperatures (NGTs) and stable isotopes independently corroborate these findings, with young water ages further supporting seasonal recharge preservation. High-altitude samples exhibit systematic deviations in dissolved noble gases, challenging conventional degassing models. The study proposes that mixing of high-altitude rainwater (≥1500 m) with low-altitude fog droplets (~400 m) during the garúa season could explain these patterns, offering new insights into groundwater dynamics in volcanic island environments.

Warrier, R. B., Castro, M. C., & Hall, C. M. (2012). Recharge and source‐water insights from the Galapagos Islands using noble gases and stable isotopes. Water Resources Research, 48(3). Portico. https://doi.org/10.1029/2011wr010954