Geochemical data collected in shallow groundwater and river water in a subpolar environment (Matane river, QC, Canada)

The study is based on a complex and unique data set of radon-222 activity (i.e., 222Rn), water stable isotope (i.e., _18O), and ancillary physicochemical parameters (i.e., temperature, electrical conductivity, pH) undertaken to better understand the hydrogeochemical connectivity between groundwater and river water in a meander floodplain (Matane River, QC, Canada). Using an array of 21 piezometers inserted into an 18 ha meander floodplain, the geochemical properties of shallow groundwater were investigated over nine sampling campaigns between 2011 and 2017. The objective was to explore the seasonal geochemical variations in response to river discharge with a specific focus on the spatial extent of the hyporheic zone.