@Article{RN433, Author = {Massmann, G. and Sültenfuß, J. and Pekdeger, A.}, Journal = {Water Resources Research}, Pages = {1-13}, Title = {Analysis of long-term dispersion in a river-recharged aquifer using tritium/helium data}, Volume = {45, W02431}, Year = {2009}, Abstract = {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.}, Project = {nasri}, En_type = {Journal Article}, Access = {public}, Doi = {10.1029/2007WR006746}, en_id = {433} }