Groundwater Flow Dynamics in Subarctic Beach Using Radioactive and Stable Isotopes, Gulf of St. Lawrence, Qc

This dataset presents a study of groundwater dynamics along a subarctic coastal environment of the St. Lawrence Gulf. For this purpose, sampling was conducted along a sandy beach located at the base of coastal cliffs in Rivière St. Jean, Quebec, Canada. Water samples were collected to measure concentrations of stable water isotopes (δ2H and δ18O) and short-lived radioisotopic tracers (222Rn, 223Ra, 224Raex). Additional measurements included water temperature and salinity to characterize basic properties of the water masses. Samples were collected from the cliffs, the beach and the seawater. Three sampling campaigns were conducted in 2023 to capture seasonal variations: February (freezing period), April (thawing period) and October (before the new freezing period). A total of 54 samples were collected in these periods to document temporal changes in groundwater flow patterns under variable ice conditions. The results obtained provide significant insights into groundwater recirculation processes and freshwater contribution rates in seasonally frozen coastal environments.