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).本研究针对注入波罗的海南部的瓦诺河（Warnow River）开展了同位素水文生物地球化学组成的时间序列研究。本次采样周期为2017至2021年，共计五年，采样点位设置于河流抵达河口前的河段。采用伸缩杆与塑料烧杯采集表层水样，并将水样妥善保存以用于后续分析。常量元素、微量元素及选定营养盐的测定采用电感耦合等离子体发射光谱仪（ICP-OES，iCAP 7400 Duo，赛默飞世尔科技（Thermo Fischer Scientific））完成；铵态氮（NH₄⁺）与硝态氮（NO₃⁻）的浓度采用QuAAtro全自动化学分析仪系统测定；溶解无机碳（DIC）及其碳同位素组成（δ¹³C_DIC）采用与Gasbench II联用的同位素气体质谱仪（MAT 253）测定；溶解有机碳（DOC）及其碳同位素组成（δ¹³C_DOC）采用Elementar iso TOC cube联用赛默飞MAT 253质谱仪完成测定；水体氢同位素（δ²H_H₂O）与氧同位素（δ¹⁸O_H₂O）采用腔环衰荡光谱（Cavity Ring-Down Spectroscopy，CRDS，Picarro L2140-I）系统测定；硫酸盐的硫同位素（δ³⁴S）与氧同位素（δ¹⁸O_SO₄）采用与EA-Isolink（赛默飞世尔科技（Thermo-Fisher-Scientific））联用的MAT253气体同位素质谱仪（赛默飞世尔-菲尼根（Thermo-Finnigan））完成测定；镭-224（²²⁴Ra）采用镭延迟符合计数器（Radium Delayed Coincidence Counters，RaDeCC）测定。