Data of monitoring the Oplotnica River silicate catchment (Slovenia) using stable carbon and nitrogen isotopes

Herein, we present a dataset of the geochemical and isotopic characteristics of water collected from September 2012 to June 2014 to evaluate biogeochemical processes within the Oplotnica River silicate catchments. Additionally, we collected soil samples at Javorski creek to characterize the soil profiles using stable isotopes of carbon and nitrogen. Discharge and temperature data for the Oplotnica River at the Perovec gauging station were gathered from the Slovenian environment agency. Temperature at both Javorski and Lukanjski creeks was measured on-site, while pH and conductivity were measured in the lab with Metrohm pH low ionic strength glass electrode and Pt1000 electroconductivity electrode, connected to Metrohm 712 Conductometer. Cations (Na+, K+, Ca2+, Mg2+, Mn2+, NH4+) were analyzed with Metrohm Metrosep C4-150/4.0 column without suppression and anions (NO3-, NO32-, SO42-, Cl-, PO43-) with Metrohm Metrosep A Supp 5-150/4.0 column with chemical suppression. Both connected in Metrohm Ion Chromatography modular system. Total alkalinity was measured with double-end point titration (pH=4.5, 4.2) measuring pH with Metrohm pH low ionic strength glass electrode and titrating with 0.01 M HCl controlled by Metrohm 702 SM Titrino titrator. Dissolved organic carbon (DOC) was measured with TOC analyser Shimadzu TOC-5000A as a difference between dissolved total carbon (DTC) and dissolved inorganic carbon (DIC). Thermodynamic modeling was performed with the PHREEQC speciation program to evaluate pCO2 and the saturation state of calcite and dolomite. The major solute composition of the analyzed surface water was as follows: Na+Ca2+Mg2+K+ and HCO3-SO42-Cl-NO3-. In surface water the δ13CDIC ranged from -26.1‰ to -1.4‰, and the 13CPOC from -28.2 to -22.3‰, and 15N from -2.2 to 2.6‰ (measured only in September 2012). 13Corg. ranged from -28.3 to -24.9‰, while 15N ranged from -4.9 to 5.4‰ at three soil profiles (up to a depth of 70 cm) at Tratice I, II and III locations at Javorski creek. Characteristic plants within catchment area have 13C in the range from -31.2 to -29.2‰ and 15N in the range from -8.0 to -5.5‰. Data were collected through field and laboratory analyses. These data were used to calculate saturation indices, partial pressure of CO2 (SIcalcite, SIdolomite, pCO2), and to perform a mass balance calculation of carbon to determine the processes that contribute most to the isotopic composition of dissolved inorganic carbon (δ13CDIC). Furthermore, bicarbonate weathering intensity was calculated within the catchment area. The main conclusions are that the saturation index of calcite (SIcalcite) ranges from -6.1 to -1.9, and the saturation index of dolomite (SIdolomite) ranges from -12.7 to -4.2. The bicarbonate weathering intensity is 10.4 mmol/km²·s, which is typical for silicate catchments.本研究构建了2012年9月至2014年6月采集的水样数据集，涵盖地球化学与同位素特征，用于解析奥普洛特尼察河（Oplotnica River）硅酸盐流域内的生物地球化学过程。此外，我们在亚沃尔斯基溪（Javorski creek）采集了土壤样品，借助碳、氮稳定同位素对土壤剖面进行特征表征。 奥普洛特尼察河佩罗韦茨水文监测站（Perovec gauging station）的流量与水温数据取自斯洛文尼亚环境署。亚沃尔斯基溪与卢坎斯基溪（Lukanjski creeks）的水温采用现场测定方式，而pH值与电导率则在实验室中使用Metrohm低离子强度pH玻璃电极与Pt1000电导电极进行测定，上述电极连接至Metrohm 712电导仪。阳离子（Na+、K+、Ca2+、Mg2+、Mn2+、NH4+）采用Metrohm Metrosep C4-150/4.0色谱柱进行非抑制型分析，阴离子（NO3-、NO32-、SO42-、Cl-、PO43-）采用Metrohm Metrosep A Supp 5-150/4.0色谱柱进行化学抑制型分析，两套色谱系统均集成于Metrohm离子色谱模块化平台中。总碱度采用双终点滴定法（pH=4.5、4.2）测定：以Metrohm低离子强度pH玻璃电极监测pH值，使用Metrohm 702 SM Titrino滴定仪以0.01 mol/L HCl进行滴定。溶解有机碳（Dissolved Organic Carbon, DOC）采用Shimadzu TOC-5000A型总有机碳分析仪，通过溶解总碳（Dissolved Total Carbon, DTC）与溶解无机碳（Dissolved Inorganic Carbon, DIC）的差值计算得到。 本研究采用PHREEQC形态模拟程序开展热力学建模，以计算二氧化碳分压（pCO2）以及方解石、白云石的饱和状态。 所分析地表水的主要溶质组成如下：Na+＞Ca2+＞Mg2+＞K+，HCO3-＞SO42-＞Cl-＞NO3-。地表水中的δ13CDIC取值范围为-26.1‰至-1.4‰，δ13CPOC为-28.2‰至-22.3‰，δ15N为-2.2‰至2.6‰（仅于2012年9月测定）。亚沃尔斯基溪三处土壤剖面（采样深度达70cm，对应Tratice I、II、III点位）的δ13Corg.取值范围为-28.3‰至-24.9‰，δ15N为-4.9‰至5.4‰。流域内典型植物的δ13C取值范围为-31.2‰至-29.2‰，δ15N为-8.0‰至-5.5‰。 本研究通过野外调查与实验室分析获取上述数据，用于计算饱和指数、二氧化碳分压（pCO2）以及方解石饱和指数（SIcalcite）、白云石饱和指数（SIdolomite），并开展碳质量平衡计算，以明确对溶解无机碳同位素组成（δ13CDIC）贡献最大的生物地球化学过程。此外，本研究还计算了流域内的碳酸氢盐风化强度。主要结论如下：方解石饱和指数（SIcalcite）取值范围为-6.1至-1.9，白云石饱和指数（SIdolomite）为-12.7至-4.2；碳酸氢盐风化强度为10.4 mmol/(km²·s)，这一数值符合硅酸盐流域的典型特征。