Evaluation of methods to sample fecal indicator bacteria in foreshore sand and pore water at freshwater beaches

Laura J. Vogel, Thomas A. Edge, Denis M. O'Carroll, Helena M Solo-Gabriele, Caitlin S.E. Kushnir, Clare E. Robinson

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Fecal indicator bacteria (FIB) are known to accumulate in foreshore beach sand and pore water (referred to as foreshore reservoir) where they act as a non-point source for contaminating adjacent surface waters. While guidelines exist for sampling surface waters at recreational beaches, there is no widely-accepted method to collect sand/sediment or pore water samples for FIB enumeration. The effect of different sampling strategies in quantifying the abundance of FIB in the foreshore reservoir is unclear. Sampling was conducted at six freshwater beaches with different sand types to evaluate sampling methods for characterizing the abundance of E. coli in the foreshore reservoir as well as the partitioning of E. coli between different components in the foreshore reservoir (pore water, saturated sand, unsaturated sand). Methods were evaluated for collection of pore water (drive point, shovel, and careful excavation), unsaturated sand (top 1 cm, top 5 cm), and saturated sand (sediment core, shovel, and careful excavation). Ankle-depth surface water samples were also collected for comparison. Pore water sampled with a shovel resulted in the highest observed E. coli concentrations (only statistically significant at fine sand beaches) and lowest variability compared to other sampling methods. Collection of the top 1 cm of unsaturated sand resulted in higher and more variable concentrations than the top 5 cm of sand. There were no statistical differences in E. coli concentrations when using different methods to sample the saturated sand. Overall, the unsaturated sand had the highest amount of E. coli when compared to saturated sand and pore water (considered on a bulk volumetric basis). The findings presented will help determine the appropriate sampling strategy for characterizing FIB abundance in the foreshore reservoir as a means of predicting its potential impact on nearshore surface water quality and public health risk.

Original languageEnglish (US)
Pages (from-to)204-212
Number of pages9
JournalWater Research
Volume121
DOIs
StatePublished - Sep 15 2017

Fingerprint

Beaches
Bacteria
porewater
beach
Sand
bacterium
sand
Water
Escherichia coli
Sampling
Surface waters
sampling
surface water
Excavation
indicator
method
evaluation
Sediments
excavation
Public risks

Keywords

  • Beaches
  • E. coli
  • Recreational water quality
  • Sampling methods
  • Sand

ASJC Scopus subject areas

  • Ecological Modeling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

Cite this

Evaluation of methods to sample fecal indicator bacteria in foreshore sand and pore water at freshwater beaches. / Vogel, Laura J.; Edge, Thomas A.; O'Carroll, Denis M.; Solo-Gabriele, Helena M; Kushnir, Caitlin S.E.; Robinson, Clare E.

In: Water Research, Vol. 121, 15.09.2017, p. 204-212.

Research output: Contribution to journalArticle

Vogel, Laura J. ; Edge, Thomas A. ; O'Carroll, Denis M. ; Solo-Gabriele, Helena M ; Kushnir, Caitlin S.E. ; Robinson, Clare E. / Evaluation of methods to sample fecal indicator bacteria in foreshore sand and pore water at freshwater beaches. In: Water Research. 2017 ; Vol. 121. pp. 204-212.
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