Assessing silicate catchment dynamics of the oplotnica river (Slovenia) through stable carbon and nitrogen isotopesKanduč, Tjaša (Avtor) Vrabec, Mirijam (Avtor) Verbovšek, Timotej (Avtor) McIntosh, Jennifer (Avtor) Žlindra, Daniel (Avtor) Vilhar, Urša (Avtor) river systemssilicate catchmentwater–soil interactionsThis study investigated the sources of carbon and nitrogen in a small, silicate-dominated catchment (Oplotnica River, Pohorje, Slovenia) with two creeks, Lukanjski and Javorski, from 2012 to 2014. Additionally, carbon and nitrogen cycling in soil profles was studied at Javorski Creek. Isotopic analyses of river water, particulates, and sediments provided a more holistic view of the sources of carbon and nitrogen, weathering contributions, and the evasion or sequestration of CO2 in the atmosphere within the catchments. The weathering of rocks, such as granodiorite and quartz diorite, infuences water geochemistry. The Oplotnica River and its tributaries were characterized by the ion composition: Na+ > Ca2+ > Mg2+ > K+ and HCO3 − > SO4 2− > Cl− > NO3 −. Partial pressure of CO2 concentrations in river and creeks ranged from 1.1 to 13.4 times that of atmospheric pressure, representing a source of CO2 to the atmosphere. The carbon isotope value of dissolved inorganic carbon (δ13CDIC) ranged from−9.8 to−1.4‰ in river, while in the creeks, it ranged from−26.1 to−4.7‰, refecting the degradation of organic matter and exchange with the atmosphere. The intensity of bicarbonate weathering for the Oplotnica River at its gauging station was 10.4 mmol/(l⋅km2 ⋅s), characteristic of silicate watersheds. The isotopic composition of carbon (δ13C) and nitrogen (δ15N) in river sediments refects values typical of soil and temperate (C3) plants. This study is signifcant on both local and global levels, as it addresses the contribution of weathering rates and the release of CO2 to the atmosphere from small silicate watersheds.20252026-01-21 10:28:34Neznano25463UDK: 502/504ISSN pri članku: 1573-1421DOI: 10.1007/s10498-025-09439-wCOBISS_ID: 234492675sl