摘要:are riparian, there are characteristic differencesbetween them. In some cases, river water transittime is only around two weeks, while in othercases it can take several decades. Previousstudies carried out within the frameworkof international cooperation (in the upperDanube area: the Vienna basin, Szigetköz, andBudapest) proved that the isotopic compositionof Danube river water differs significantlyfrom background water recharging from localprecipitation.