Dynamics of respired dissolved organic carbon in a stream data

This resource contains the results from a set of whole-stream isotopically-label dissolved organic carbon (13C-DOC) addition experiments conducted in August 2019 to directly trace the uptake and mineralization of DOC into the stream DIC pool. These experiments were conducted in Blaine Creek, an open-canopy, agricultural, spring-fed stream located a the Montana State University Northwestern Agricultural Research Center in Creston, Montana, USA. Between 8 and 15 August 2019, we conducted three separate pulse releases of NaCl (used as a conservative solute tracer) and a reactive 13C-labeled DOC substrate, either 13C-labeled glucose on 8 and 15 August 2019 (as 3 grams of D-glucose dissolved in 100 mL of deionized water) or 13C-labeled leaf leachate on 9 August 2019. The 13C-labeled leaf leachate was prepared following Kaplan et al. (2008) using uniformly labeled 13C red fescue in deionized water. During each pulse release, we sampled for DOC, pH, alkalinity and CO2 at two sampling stations 41 (denoted as \"upstream\") and 61 meters (denoted as \"downstream\") downstream of the addition site, respectively. We also deployed sensors to collect dissolved O2 and temperature (PME miniDOT) and dissolved CO2 (Eosense eosGP) sensors at 10 minute intervals throughout the study period to estimate CO2 emission fluxes and daily rates of of ecosystem metabolism (i.e., gross primary production and ecosystem respiration). The file \"blaine_65_oxy.csv\" contains the 10-minute interval temperature and dissolved O2 sensor data from the downstream sampling station, which was used to estimate daily rates of metabolism. The file \"pco2_blaine.csv\" contains the 10-minute interval temperature and dissolved CO2 data from both the upstream (denoted as \"white\" in column names) and downstream (denoted as \"bela\" in column names) sampling stations. The file \"site_data.csv\" contains relevant information to each pulse release such as reach length (in meters), mean wetted width (in meters), conservative and reactive tracer masses (in grams for \"salt_mass\" and \"sugar mass\", in milligrams for \"doc_mass_13C_mg\"), alkalinity, travel time between addition and sampling station (in minutes), as well as velocity (v.ms, in meters per second) and discharge (Qest.Ls, in liters per second) estimated from the conservative tracer during each addition. For samples collected throughout each pulse release, we quantified 13-CO2 from headspace equilibrated samples immediately following the experiments using a Cavity Ring-Down Spectrometer (CRDS; Picarro), alkalinity via end-point titration, and DOC concentrations and del13C-DOC using a TOC analyzer (Aurora 1030, OI Analytical) coupled to a Picarro CRDS. The folder \"DOC_runs\" contains individual CSV files for each pulse release with the DOC concentration (\"DOC_conc\", in milligrams per liter), del13C-DOC (\"Delta 13C\"), and alkalinity (in meq/L) for each sampling timepoint. The folder \"picarro_runs\" contains individual CSV files for each pulse release with the CO2 and CH4 concentration (\"CO2\" and \"CH4\" in ppm), del13C-CO2 (\"delCO2\"), and del13C-CH4 (\"delCH4\") values for each sampling timepoint. All file and column names are preserved to ensure coding and modeling workflows associated with this resource function, which can be found at https://github.com/robohall/DOC_uptake References Kaplan, L. A., T. N. Weigner, J. D. Newbold, P. H. Ostrom, and H. Gandhi. 2008. Untangling the complex issue of dissolved organic carbon uptake: a stable isotope approach. Freshwater Biology, 53:855–864.本数据集包含2019年8月开展的一系列全溪流同位素标记溶解有机碳（13C-DOC）添加实验的结果，旨在直接示踪DOC被溪流溶解无机碳（DIC）库吸收并矿化的过程。本实验在美国蒙大拿州克里斯顿的蒙大拿州立大学西北农业研究中心境内的布莱恩溪（Blaine Creek）开展，该溪流为开阔林冠、农业流域的泉水补给型溪流。 2019年8月8日至15日期间，我们先后开展了三次独立的脉冲投放实验，分别投放作为保守溶质示踪剂的氯化钠（NaCl）与反应性13C标记DOC底物：8月8日和15日投放13C标记葡萄糖（将3克D-葡萄糖溶解于100毫升去离子水中），8月9日投放13C标记叶片淋溶液。13C标记叶片淋溶液的制备参照Kaplan等人（2008）的方法，以去离子水中的均匀标记13C紫羊茅为原料制备。 每次脉冲投放实验期间，我们分别在投放点下游41米（记为“上游采样站”）和61米（记为“下游采样站”）两个采样点位采集DOC、pH、碱度与CO2样品。本研究期间，我们还以10分钟的时间间隔部署了溶解氧与温度传感器（PME miniDOT）以及溶解CO2传感器（Eosense eosGP），用于估算CO2排放通量以及生态系统每日代谢速率（即总初级生产力与生态系统呼吸速率）。 文件"blaine_65_oxy.csv"包含下游采样站的10分钟间隔温度与溶解氧传感器数据，该数据用于估算每日生态系统代谢速率。文件"pco2_blaine.csv"包含上游采样站（列名标注为“white”）与下游采样站（列名标注为“bela”）的10分钟间隔温度与溶解CO2数据。文件"site_data.csv"包含每次脉冲投放实验的相关参数，包括河段长度（单位：米）、平均湿润宽度（单位：米）、保守与反应性示踪剂质量（salt_mass和sugar_mass单位为克，doc_mass_13C_mg单位为毫克）、碱度、投放点与采样站之间的运移时间（单位：分钟），以及根据每次投放实验的保守示踪剂估算得到的流速（v.ms，单位：米每秒）与径流量（Qest.Ls，单位：升每秒）。 针对每次脉冲投放实验采集的样品，我们在实验结束后立即使用腔衰荡光谱仪（Cavity Ring-Down Spectrometer，CRDS；Picarro）对顶空平衡样品中的13C-CO2进行定量，通过终点滴定法测定碱度，并使用耦合Picarro CRDS的总有机碳分析仪（Aurora 1030，OI Analytical）测定DOC浓度与δ13C-DOC值。 "DOC_runs"文件夹包含每次脉冲投放实验的独立CSV文件，其中存储了各采样时间点的DOC浓度（DOC_conc，单位：毫克每升）、δ13C-DOC（对应列名“Delta 13C”）以及碱度（单位：毫克当量每升，meq/L）。"picarro_runs"文件夹包含每次脉冲投放实验的独立CSV文件，其中存储了各采样时间点的CO2与CH4浓度（CO2和CH4，单位：ppm）、δ13C-CO2（delCO2）以及δ13C-CH4（delCH4）值。 所有文件与列名均保留原样，以确保与本数据集相关的编码与建模流程可正常运行，相关代码可访问https://github.com/robohall/DOC_uptake获取。 参考文献 Kaplan, L. A., T. N. Weigner, J. D. Newbold, P. H. Ostrom及H. Gandhi. 2008. 解析溶解有机碳吸收的复杂问题：一种稳定同位素方法. 淡水生物学（Freshwater Biology）, 53:855–864.