Carbon dioxide flux and isotopic composition from sedimentary rock weathering, Waiapu River catchment, New Zealand

These data were collected to study oxidative weathering processes in the Waiapu River catchment, New Zealand, with potential carbon release sourced from the oxidation of petrogenic organic carbon or carbonate dissolution coupled to the oxidation of sulfide minerals. There, in mudstones exposed in a highly erosive gully complex, in situ CO2 emissions were measured with drilled gas accumulation chambers following the design by Soulet et al. (2018, Biogeosciences 15, 4087-4102, https://doi.org/10.5194/bg-15-4087-2018). Temporal and spatial variability in CO2 flux can be put in context with environmental changes (e.g., temperature and hydrology). For this, CO2 release from 5 different chambers, which were installed over a transect of ~ 10 m length in a gully above a nearby streambed, was measured several times over a short study period (circa one week). In addition, the gaseous CO2 storage (partial pressure) in the shallow weathering zone was measured prior to a CO2 flux measurement. To understand the source of CO2, gas samples were collected and their stable and radioactive carbon isotope compositions determined. In this process, we identified a contaminant, which was associated with the chamber installation, that can be traced in the gas samples that were collected within 4 days following the installation. Details of the subsequent data analysis and interpretation can be found in: Roylands et al. 2022, Chemical Geology: Capturing the short-term variability of carbon dioxide emissions from sedimentary rock weathering in a remote mountainous catchment, New Zealand. This work was supported by the European Research Council (Starting Grant to Robert G. Hilton, ROC-CO2 project, grant 678779).本数据集采集自新西兰怀阿普河流域（Waiapu River catchment），旨在探究该区域的氧化风化过程，其潜在碳释放来源包括岩石成因有机碳的氧化，或是与硫化物矿物氧化耦合的碳酸盐溶解过程。研究区域的高度侵蚀性冲沟群内出露有泥岩，研究人员采用Soulet等（2018，《生物地球科学》15卷，4087-4102，https://doi.org/10.5194/bg-15-4087-2018）设计的钻孔式气体蓄积室，原位测量了该区域的二氧化碳排放通量。 二氧化碳通量的时空变化可结合环境要素变化（如温度、水文条件）展开分析。为此，研究人员在邻近河床上方的冲沟内，沿约10米长的样带布设了5个不同的气体蓄积室，并在为期约一周的短期研究周期内多次测量其二氧化碳释放量。此外，在开展二氧化碳通量测量前，研究人员还对浅层风化带内的气态二氧化碳储量（分压）进行了测定。 为明确二氧化碳的来源，研究人员采集了气体样本并测定其稳定碳同位素与放射性碳同位素组成。在此过程中，研究人员发现了一类与气体蓄积室安装作业相关的污染物，该污染物可在安装后4天内采集的气体样本中被追溯检出。 后续数据分析与阐释的详细内容可参见：Roylands等2022年发表于《化学地质学》的论文《捕捉新西兰偏远山区流域沉积岩风化产生的二氧化碳排放短期变化》。本研究得到欧洲研究委员会（ERC）资助：授予Robert G. Hilton的启动经费，ROC-CO2项目，项目编号678779。