Distribution of H and O stable isotopes in the surface waters of the Sava River, the major tributary of the Danube River

摘要

The presented paper describes spatial and temporal variations in extended stable isotope datasets of hydrogen and oxygen (delta H-2 and delta O-18) in the Sava River water that were used to estimate the mean residence time (MRT) of stream water using an exponential flow model. The re-examining MRT was 2 years in the Slovenian part of the Sava River and was in a good agreement with previous estimates and with the MRT estimated in the Sava River at Ostrulnica near Belgrade, Serbia. A MRT 2.2 years was observed in the Danube River at Vina also near Belgrade. The spatial distribution of delta O-18 in precipitation over the Sava River Basin (SRB) was mapped based on the long-term weighted mean annual delta O-18 values and established relationship with various geographical controls (latitude, longitude and altitude). The modelled delta O-18 values in precipitation agree with the measured values in the surface river water at different locations indicating that the spatial variation in the isotopic composition of precipitation is the dominant factor controlling surface water isotope ratios over the SRB.