Distribution of stable isotopes in the River Sava in Serbia

Grab water samples were collected from the research ship ‘ARGUS’ at four locations in Serbia, Ostružnica (17 rkm), Šabac (103.6 rkm), Sremska Mitrovica (136.4 rkm), and Jamena (195.0 rkm) from the mid-river, and near the left and right banks during longitudinal survey of the River Sava performed in August 2006. The stable isotope ratios of hydrogen and oxygen (2H/1H and 18O/16O) were determined along with other physicochemical and biological parameters. The δ18O values of river water ranged from −9.2‰ to −8.5‰, and δ2H values ranged from −66‰ to −61‰. Samples taken from the mid-river along the main stem of the Sava at all examined locations appeared to be isotopically the same stream water with a value of −9.0 ± 0.1‰ for δ18O and −65 ± 1.0‰ for δ2H. The results are considered in relation to the isotopic changes known to occur in water subjected to evaporation and mixing.