Biogeochemical Data from Field Samples and Laboratory Experiments, Boulder Creek Watershed, Colorado (2019-2023)

Biogeochemical processes are key drivers of chemical solubility and mobilization. Understanding these processes will lead to improved predictive capabilities and may aid with watershed management decisions. This data release presents results from the Boulder Creek, Colorado watershed, including analyses of water and sediment. From April to August 2019, water samples were collected weekly at 2 sites along Boulder Creek and 4 tributary sites draining into Boulder Creek. In August 2022, water samples were collected every 2 hours for 34 hours at 2 sites on Boulder Creek (upstream and downstream of the city of Boulder). Samples for both studies were analyzed for major cations and anions, dissolved organic carbon, UV absorbance, total dissolved nitrogen, ammonium, nitrate, alkalinity, trace metals, water isotopes, and field parameters including dissolved oxygen, pH, water temperature, and specific conductance. In August 2022, bed sediment (0-3 cm depth) samples were collected at 8 sites along Boulder Creek. The sediment was dried, sieved, pulverized, digested, and then analyzed for metals, total carbon, sulfur, and carbonate. In 2021 and 2022, laboratory incubations of sediment and stream water were conducted to assess how different oxidation-reduction conditions affect metal and nutrient concentrations. Sediment cores (0-5 cm and 5-10 cm depth) and surface water were collected from Boulder Creek at three sites upstream, within, and downstream of the city of Boulder. Samples were collected from incubation reactors over time and analyzed for major cations and anions, dissolved organic carbon, UV absorbance, total dissolved nitrogen, ammonium, nitrate, trace metals, total arsenic, pH, and specific conductance. Sediments used for the incubations were further characterized by sequential extractions with hydroxylamine and dithionite and analyzed for major cations and trace metals. Site information, soil characterization details, incubation preparation and biogeochemical nutrient data, sediment sequential extraction data, and water-quality data are presented in this data release as ten comma-separated values (.csv) formatted tables. A data dictionary file describes the data found in the .csv files. Method details and references are located in the metadata file “Boulder Creek Watershed Data (2019-2023).xml.”