ORIGINAL PAPER Chemical Dynamics and Evaluation of Biogeochemical Processes in Alpine River Kamnis ˇka Bistrica, North Slovenia Tjas ˇa Kanduc ˇ • Martina Burnik S ˇ turm • Jennifer McIntosh Received: 7 January 2013 / Accepted: 24 June 2013 / Published online: 3 July 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract Biogeochemical processes were investigated in alpine river—Kamnis ˇka Bis- trica River (North Slovenia), which represents an ideal natural laboratory for studying anthropogenic impacts in catchments with high weathering capacity. The Kamnis ˇka Bis- trica River water chemistry is dominated by HCO 3 - , Ca 2? and Mg 2? , and Ca 2? /Mg 2? molar ratios indicate that calcite weathering is the major source of solutes to the river system. The Kamnis ˇka Bistrica River and its tributaries are oversaturated with respect to calcite and dolomite. pCO 2 concentrations were on average up to 25 times over atmo- spheric values. d 13 C DIC values ranged from -12.7 to -2.7 %, controlled by biogeo- chemical processes in the catchment and within the stream; carbonate dissolution is the most important biogeochemical process affecting carbon isotopes in the upstream portions of the catchment, while carbonate dissolution and organic matter degradation control carbon isotope signatures downstream. Contributions of DIC from various biogeochemical processes were determined using steady state equations for different sampling seasons at the mouth of the Kamnis ˇka Bistrica River; results indicate that: (1) 1.9–2.2 % of DIC came from exchange with atmospheric CO 2 , (2) 0–27.5 % of DIC came from degradation of organic matter, (3) 25.4–41.5 % of DIC came from dissolution of carbonates and (4) 33–85 % of DIC came from tributaries. d 15 N values of nitrate ranged from -5.2 % at the Electronic supplementary material The online version of this article (doi:10.1007/s10498-013-9197-4) contains supplementary material, which is available to authorized users. T. Kanduc ˇ(&) Department of Environmental Sciences, Joz ˇef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia e-mail: tjasa.kanduc@ijs.si M. B. S ˇ turm Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Savoyenstrasse 1, 1160 Vienna, Austria J. McIntosh Department of Hydrology and Water Resources, University of Arizona, 1133 E. James E., Rogers Way, Tucson, AZ, USA 123 Aquat Geochem (2013) 19:323–346 DOI 10.1007/s10498-013-9197-4