Analysis of long-term dispersion in a river-recharged aquifer using tritium/helium data

Large-scale dispersion was studied in an unconsolidated, sandy, glaciofluvial, river-recharged, and confined aquifer in Germany. Groundwater observation wells from a 3.5-km-long transect located in flow direction from the river Oder into a large lowland area (Oderbruch polder) were sampled for noble gases in order to date the groundwater with the tritium and helium (3H-3He) technique. The apparent 3H-3He ages of the groundwater increased from only a few months to >40 years along the flow path. Highest values for initial 3H (sum of 3H and its decay product tritiogenic helium, 3Hetri) were encountered in 2.6-km river distance. Concentrations of 4He in the water increased to 1.1 × 10-7 cm3 STP/g with distance from the river. The initial 3H data enabled an estimation of the longitudinal dispersivity with a simplified one-dimensional transport model. The best fit of modeled and measured initial H data was obtained using a dispersivity of 120 m. Deviations of modeled hydraulic ages and measured apparent 3H- 3He ages for older samples can be explained by dispersive mixing.

Do you want to download “{filename}” {filesize}?

In order to optimally design and continuously improve our website for you, we use cookies. By continuing to use the website, you agree to the use of cookies. For more information on cookies, please see our privacy policy.