Suspended sediment concentrations from water samples collected from the shallows and a tidal creek of Northern San Francisco Bay, California, 2022-2023

Water samples were collected periodically between April 2022 and June 2023 using a peristaltic pump, Niskin bottle, or sample bottle. Sampling positions were recorded using a hand-held global navigation satellite system (GNSS) receiver. Samples were placed in cold storage until processed.

The suspended sediment concentrations of the samples were determined in the USGS Pacific Coastal and Marine Science Center sediment lab. Suspended sediment concentrations were determined by a filtering a known, subsampled volume of sample through a pre-weighed filter, which is then dried and reweighed to determine the mass of suspended sediment on the filter. Suspended sediment concentrations were calculated by subtracting the weight of the filter from the weight of the reweight (post filtering) filter. The resulting weight (in milligrams) is divided by the volume of sample filtered (in liters) to get the concentration of suspended sediments.

The suspended sediment carbon analysis was performed by the PCMSC sediment and carbon labs employing a coulometric titration technique described in Engleman and others (1985) and UIC operating manuals for the UIC CM5200 autosampler furnace, the UIC CM5230 acidification module, and the UIC CM5017 coulometer. Total carbon (TC), total inorganic carbon (TIC), total organic carbon (TOC) and percent calcium carbonate (CaCO3) are reported as percent dry weight. Approximately 1 liter of the water-sediment samples were centrifuged to remove the water and concentrate the sediment. The sediment was dried and pulverized and ready to be processed for percent carbon analysis. For TC analysis, the dried samples were weighed and wrapped in an aluminum capsule then combusted at 950 degrees Celsius in an UIC CM5200 autosampler furnace attached to an UIC CM5017 coulometer. The carbon dioxide (CO2) produced by combusting the sample was then converted to TC by the UIC CM5017 coulometer. For TIC, the dried samples were weighed and loaded into an UIC CM5230 acidification module attached to an UIC CM5017 coulometer. The samples were then digested in a perchloric acid solution, and the CO2 generated was measured and converted to TIC. Two analyses per sample were run and the results were averaged. TOC was calculated by subtracting TIC from TC. The TIC value was then multiplied by 8.333 (the molar stochiometric ratio of CaCO3 to C) to convert TIC to percent CaCO3.