Parent and alkylated polycyclic aromatic hydrocarbons (PAHs) and per- and polyfluoroalkyl substances (PFAS) in north San Francisco Bay, Napa River, and Sonoma Creek in 2018 and 2019

GRAIN SIZE: Duplicate analyses of sediment grain size, run every 20 samples, are within 15 percent. TOTAL ORGANIC CARBON (TOC): TOC analyses were run in duplicate. Percent differences between duplicates range from less than 1 percent (8 samples) to 59 percent (Marsh19-06). The median TOC difference between duplicates is 3 percent (n=35). CARBON TO NITROGEN RATIOS: Precision of total carbon to total nitrogen ratios relative to reference materials of known composition is better than 1 percent. STABLE CARBON ISOTOPE RATIOS (d13C): The analytical precision of d13C ratios relative to internationally calibrated in-house reference materials is better than 0.2 permil. SHORT-LIVED COSMOGENIC RADIONUCLIDES: Sample activities were calculated by comparison to certified reference materials with the same geometry and counting time. Reported uncertainties include 1 standard deviation counting errors, detector efficiency, and background corrections. Radioisotope activities three or more times higher than reported uncertainties are considered to be statistically significant. POLYCYCLIC AROMATIC HYDROCARBONS (PAHs): Quality Control (QC) measures for PAHs included external calibration curves, internal standards, lab blanks, spiked matrix samples, and field and lab duplicates. All raw data are shown without censorship with corresponding QC flags and definitions. Percent recoveries of PAH compounds in spiked matrix samples are acceptable between 50 percent and 150 percent except for 1,4,6,7-Tetramethylnaphthalene, which is up to 200 percent. A field duplicate collected at SP19-05 has PAH concentrations that differed by 1 percent to 55 percent among compounds without quality control flags (n=64) and the median difference is 19 percent. A PAH Lab duplicate run on SP19-08 has concentrations that differed by 1 percent to 40 percent among compounds without quality control flags (n=64). The median difference is 13 percent. PAH weights and concentrations are reported with three significant figures (XX.X, X.XX, 0.XXX, and 0.0XXX) rather than a fixed measurement resolution. PER- AND POLY-FLUOROALKYL SUBSTANCES (PFAS): QC measures for PFAS included external calibration curves, internal standards, lab blanks, spiked matrix samples, and field and lab duplicates. Percent recoveries of PFAS compounds in spiked matrix samples are acceptable between 40 percent and 150 percent except for 8:2 Fluorotelomersulfonate, which is up to 170 percent. No PFAS were detected in the field duplicate. Lab duplicates were run on Marsh19-02 and Marsh19-07. One PFAS compound (PFOS) detected in both samples and their duplicates differed by 122 percent (Marsh19-02) and 15 percent (Marsh19-07), the former due to low concentration levels less than 5 times the Reporting Limit (RL). One PFAS compound (6:2 FTS) was detected in the duplicate of Marsh19-02 and not in the original sample but was only 3 times the Lab Blank value and should be considered an estimated maximum value. PFAS weights and concentrations are reported with three significant figures (XX.X, X.XX, 0.XXX, and 0.0XXX) rather than a fixed measurement resolution.