Temporal characterization of the isotope hydrobiogeochemistry composition of the Warnow River@en

A temporal study of the isotopic hidrobiogeochemical composition of the Warnow River, which drains into the southern Baltic Sea, has been carried out. The sampling covered five years (2017-2021) and it was carried out at a site just before the river reaches the estuary. Surface water was sampled by using a telescopic rod and a plastic beaker and preserved for further analysis. Major and trace elements and selected nutrients were measured using an ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific). Concentrations of NH4 and NO3 were measured using a QuAAtro autoanalyzer system. Dissolved inorganic carbon (DIC), and δ13CDIC were measured using an isotope gas mass spectrometer (MAT 253) coupled to a Gasbench II. Dissolved organic carbon (DOC) and δ13CDOC using an Elementar iso TOC cube with Thermo Electron MAT 253 mass spectrometry, δ18OH2O, and δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I). δ34S and δ18O of SO4 using a gas-isotope mass spectrometer MAT253 (Thermo-Finnigan) with EA-Isolink (Thermo-Fisher-Scientific). 224Ra using a Radium Delayed Coincidence Counters (RaDeCC).