Description
Thirteen samples were collected from the main pond of Famosa Slough, San Diego, CA and analyzed for the concentrations of the metals Cu, Ag, Zn, Cd and Pb. Loss on ignition and the percent detrital minerals were analyzed to indicate the metal concentrations independent of the detrital fraction. Loss on ignition was higher on the south and east sides indicating an accumulation of organics in the back of the slough. Cu appeared to be a general pollutant of the pond, while Ag was only detectable on the east side of the slough. These metals could enter the slough via the numerous drains, storm pipes and surface streets that discharge into the slough. Ag most likely enters via a fresh water stream at the south end of the main pond. Zn had generally high concentrations with the samples taken at the inlet to the slough from its channel containing the highest concentrations. This inlet is the main source of water into the slough and serves as a pathway for tidal ebb and flow from the San Diego River. Pb was the most concentrated contaminant in the slough. The highest value of 3300 ppm (leachable fraction only) also occurred at the culvert leading into the main pond. This indicates that leaded gasoline from automobile traffic on West Point Loma Blvd., which crosses over the slough where the channel and pond meet, and Interstate 8, which passes over the channel where it meets the San Diego river, are the most likely sources of lead to the Famosa Slough.
