Isotopic characteristics of the Sava River basin in Slovenia

摘要

First results of isotopic research in the Sava River basin in Slovenia are presented. The seasonal variability of δ~(18)O and δD of the river Sava reflects the isotopic composition of precipitation. Tritium concentrations up to 18.3 T.U. in the Sava River basin indicate that modern recharge occurs, except in the Krsko—Brezice area. Dissolved inorganic carbon (DIC) concentrations and its isotopic composition (δ~(13)C_(DIC)) were used to trace watershed inputs and fluvial processes affecting the inorganic pool of the carbon budget. The total DIC flux of the river Sava was estimated to be 1.10 x 10~8 mol C/day in the spring of 2004, and lower, 4.4 x 10~7 mol C/day in the fall of 2004. An isotopic mass balance calculation at the Slovenian-Croatian border show that the relative contributions of the tributaries, exchange with the atmosphere, dissolution of carbonates, and degradation of organic matter to the total DIC flux were 70, —0.9, 20, 11 in the spring, and 62, -5, 26, 17 in fall of 2004, respectively.