Water and bromide transport in a heterogeneous glacial sand

We investigated water flow and bromide transport under agricultural field c onditions, using TDR and tensiometer measurements as well as a bromide trac er experiment. The soil, an Albic Luvisol consisting of sand covering glaci al loam, is highly heterogeneous with polygon nets formed by sand-filled fr ost wedges. Water flow and bromide transport are influenced by the thicknes s of the glacial sand horizon and the soil structure. Both cause a variatio n of the actual evapotranspiration up to +/- 25 mm/ yr. Water and bromide a re preferentially transported on the inclined soil layer boundaries into th e sand wedges. From there infiltrating water may be redistributed into the surrounding glacial till. Approximately, the depths of the bromide centers of mass can be deduced using the piston flow concept. Small-scale mass bala nces of the tracer show that Vertical sections with bromide deficits and br omide surpluses are well balanced within a horizontal range of 1.8 m to 2.8 m. This distance is interpreted as the lateral influence of the sand wedge s.