Chemical variability in the Sacramento River and in Northern San Francisco Bay

Specific conductance and concentrations of alkalinity, dissolved silica, nitrate, and ammonium were measured daily in the Sacramento River flow to northern San Francisco Bay during the rainfall seasons of 1983 and 1984 (high flow) and during late summer and early fall of 1984 (low flow). Flow and concentrations of chemical species varied in response to storm events during high flow, but flow was more variable than concentrations of chemical species. Runoff from agriculturally developed areas appeared to increase specific conductance and concentrations of alkalinity during high flow. During low flow, inputs of agricultural tailwaters caused variations in concentrations of alkalinity and dissolved silica. Dilution of municipal waste by river flow caused variability in concentrations of ammonium during both high flow and low flow. Distributions of alkalinity, dissolved silica, nitrate, and ammonium were measured in northern San Francisco Bay during late summer and fall of 1984. Changes in distributions of alkalinity in the estuary were caused by variations in alkalinity in the Sacramento River. Changes in distributions of dissolved silica, nitrate, and ammonium appeared to be primarily related to variations in supply by the river and removal by phytoplankton. Effects of removal by phytoplankton were large for ammonium and dissolved silica, but appeared relatively small for nitrate.