HR: 0800h
AN: OS41A-0155    [Abstracts]
TI: Dynamics in Sand of Fecal Indicator Bacteria (FIB) and Salmonella From Contaminated Water, Runoff, and Sewage in an Urbanized Southern California Shoreline
AU: * Mika, K
EM: ktmika@gmail.com
AU: Lee, C
AU: Lin, C
AU: Imamura, G
AU: Chang, C
AU: Jay, J
AB: In urbanized coastal watersheds, FIB can come from a variety of sources, including contaminated freshwater sources such as storm drains or creeks, sewage spills, and overlying waterbodies. To investigate the impact of these sources on bacterial levels in coastal sediments and resultant impacts on water bodies, we studied these three source types in Southern California. First, we sampled at 8am and noon at three locations throughout the summer at an enclosed beach on Avalon Bay, Catalina Island, in collaboration with Southern California Coastal Water Research Project. Using membrane filtration and IDEXX substrate technology, we measured FIB levels in sediment and water and observed a positive correlation between these two factors. Second, we studied bacterial persistence in sediment using human sewage as source. To study bacterial survival in the natural environment, we tested solar disinfection with raking as a disinfection procedure after a large sewage spill in the Los Angeles area. First order decay constants for the E. coli ranged between -0.23 and -1.02 in test plots. Further bench scale studies were conducted to determine the effect of various factors on inactivation kinetics. Decay constants measured in controlled experiments in both February and June on the rooftop ranged from -0.73 to -1.54 even though both temperature and intensity of sunlight varied greatly in these months. Interestingly, microcosms subjected to constant moisture had similar decay constants for enterococci, while E. coli in moistened sand showed very low decay rates. Finally, we further investigated effects of sunlight by assessing the extent of surface sand contamination near two contaminated freshwater sources, one under constant shading, and looked for evidence of human fecal matter.
DE: 0493 Urban systems
DE: 0496 Water quality
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting