Charcoal and soil, water, and reservoir sediment-core chemistry in the North Fork Salmon Creek basin and Conconully Reservoir, Washington, 2022-2023

SEDIMENT GRAIN SIZE ANALYSIS: The laser particle counter was calibrated with three manufacturer-provided standards every day. Process duplicates were analyzed every 20 samples and were within 15 percent. CARBON ANALYSIS: Process duplicates for carbon analyses were run for every sample and were within 15 percent. SHORT-LIVED RADIONUCLIDE ACTIVITIES: Radionuclide activities were calculated by comparison to reference standards with the same geometry and counting time. Reported uncertainties include 1-standard-deviation counting errors, detector efficiency, and background corrections. Detector efficiency for Cesium-137 was determined using International Atomic Energy Agency (IAEA) Standard Reference Material 300. Detector efficiency for Lead-210 was determined using IAEA standards RGU-1 and RGTh-1. SOLID-PHASE ELEMENTAL CHEMISTRY: For elemental chemistry determinations, long-term internal reference materials were used to standardize the data. The percent recovery for all elements was within 15 percent of reference values for concentrations that were not less than five times the limit of detection. AQUEOUS MULTI-ELEMENT CHEMISTRY: USGS T-series water standards and blanks were analyzed for quality control with every run. Measured values were within +/- 20 percent of accepted values. Elements not meeting this criterion and values outside of the calibration-standard range were flagged as informational. POLYCYCLIC AROMATIC HYDROCARBONS (PAHs): External calibration curves, internal standards, lab blanks, and spiked matrix samples were analyzed with every batch. Percent recovery acceptance criteria in spiked matrix samples for the 16 priority PAHs were 70-130 percent except for Fluorene, which was 60-140 percent, and 50-150 percent for other PAHs. All quantified values are shown without censorship with corresponding lab flags.