Concentration of nutrients in water samples collected from the Upper Clark Fork River (Montana, USA) during water year 2021 (1 Oct 2020 - 30 Sept 2021)

The umbrella Upper Clark Fork River (UCFR) Long Term Research in Environmental Biology (LTREB) monitoring project generating these data is conducted separately and complementarily to the $200 million-dollar (USD) superfund project for ecological restoration of the UCFR, associated tributaries, and head water streams including Silver Bow and Warm Springs Creeks. Restoration along the Upper Clark Fork River includes removal of metal-laden floodplain soils, lowering of the floodplain to its original elevation, and re-vegetation of over 70 km of the river's floodplain closest to contaminant sources. The UCFR LTREB project includes bi-weekly water quality monitoring across a 200-km gradient of heavy metal contamination associated with historic mining. Monitoring includes inorganic phosphorus and nitrogen concentrations, biotic standing stocks, and dissolved and whole-water heavy metal concentrations. The UCFR LTREB monitoring project is conducted within the first 200 km of the Upper Clark Fork River and associated tributaries located in western Montana. The current monitoring program began in 2017 and will be completed in the year 2023, with likely funding extension to 2028. Surface water samples represented in this data product are collected from thirteen sites along the mainstem of the UCFR, and three sites representing major tributaries to the UCFR. Water samples are collected at each monitoring site in triplicate and filtered with a 0.7-µm glass fiber filter. Nutrient samples are analyzed using a spectrophotometric flow injection analyzer (AP2) for nitrate (NO3-N), soluble reactive phosphorus (SRP, as representative of PO4-P), and ammonium (NH4-N) concentrations reported in mg/L. The analysis-ready data of this dataset therefore represent Quality Assurance and Quality Control (QAQC) processed NH4-N, SRP, and NO3-N concentrations from thirteen sites along the mainstem of the UCFR and three tributaries, collected in water year 2021 (1 Oct 2020 - 30 Sept 2021).

支撑本数据集生成的克拉克福克河上游（Upper Clark Fork River, UCFR）环境生物学长期研究（Long Term Research in Environmental Biology, LTREB）监测项目，独立开展且与耗资2亿美元（美元计价）的UCFR及其附属支流、源头溪流（包括银鲍溪与暖春溪）生态修复超级基金项目形成互补。克拉克福克河上游的生态修复工作包括移除携带有重金属的河漫滩土壤、将河漫滩恢复至原始高程，以及对紧邻污染源的70余公里河漫滩进行植被恢复。UCFR LTREB项目针对历史采矿活动造成的200公里重金属污染梯度带开展每两周一次的水质监测，监测指标涵盖无机磷、氮浓度，生物现存量，以及溶解态与全水相重金属浓度。UCFR LTREB监测项目覆盖蒙大拿州西部克拉克福克河上游前200公里河段及其附属支流区域。本次监测计划于2017年启动，原定于2023年结束，目前有望获得经费延长至2028年。本数据集涵盖的地表水样本采集自UCFR干流的13个监测点位，以及UCFR主要支流的3个监测点位。各监测点位均采集三份平行水样，并使用0.7微米玻璃纤维滤膜进行过滤。营养盐样本采用分光光度流动注射分析仪（AP2）进行分析，测定硝酸盐（NO3-N）、可溶性活性磷（SRP，以PO4-P为代表）与氨氮（NH4-N）浓度，单位为mg/L。因此，本数据集的可分析数据为经过质量保证与质量控制（Quality Assurance and Quality Control, QAQC）处理后的氨氮、可溶性活性磷与硝酸盐浓度数据，采集自UCFR干流13个点位与3个支流点位，采样时段为2021水文年（2020年10月1日至2021年9月30日）。