Spatial and temporal dynamics of fecal coliform and Escherichia coli associated with suspended solids and water within five northern california estuaries

David J. Lewis, Edward R Atwill, Maria das Graças C Pereira, Ronald Bond

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Fecal coliform and Escherichia coli associated with suspended solids (SS) and water in five northern California estuaries were studied to document process influences and water quality monitoring biases affecting indicator bacteria concentrations. We collected and analyzed 2371 samples during 10 sampling events for the five studied estuaries. Concentrations during wet-season stormflow conditions were greater than during wet-season base flow and dryseason base flow conditions. Results also document concentration gradients across the length of the studied estuaries and with depth of sample collection. Highest concentrations were associated with shallow samples collected furthest inland. Corresponding decreases occurred the deeper and closer to the estuary mouth a sample was collected. Results also identify direct relationships of wind speed and discharge velocity and indirectrelationship of tide stage to indicator bacteria concentrations. Bacteria associated withsuspended solids (SS), after conversion to the same units of measurement (mass), were three orders of magnitude greater than in the water fraction. However, the mean proportion contributed by SS to composite water sample concentrations was 8% (SE 0.3) for fecal coliform and 7% (SE 0.3) for E. coli. Bacteria from the SS proportion is related to seasonality, tide stage, and discharge velocity that are consistent with mechanisms for entrainment, transport of SS, and reduced particle settling. These results are important for both managing and monitoring these systems by improving sample spatial and temporal context and corresponding bacteria concentration values across the freshwater-saltwater interface.

Original languageEnglish (US)
Pages (from-to)229-238
Number of pages10
JournalJournal of Environmental Quality
Volume42
Issue number1
DOIs
StatePublished - Jan 2013

ASJC Scopus subject areas

  • Environmental Engineering
  • Pollution
  • Management, Monitoring, Policy and Law
  • Waste Management and Disposal
  • Water Science and Technology

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