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Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water

Environmental Science and Technology

By:
, , ,
DOI: 10.1021/es203847n

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Abstract

Characterization of diel variability of fecal indicator bacteria concentration in nearshore waters is of particular importance for development of water sampling standards and protection of public health. Significant nighttime increase in Escherichia coli (E. coli) concentration in beach water, previously observed at marine sites, has also been identified in summer 2000 from fixed locations in waist- and knee-deep waters at Chicago 63rd Street Beach, an embayed, tideless, freshwater beach with low currents at night (approximately 0.015 m s–1). A theoretical model using wave-induced mass transport velocity for advection was developed to assess the contribution of surface waves to the observed nighttime E. coli replenishment in the nearshore water. Using average wave conditions for the summer season of year 2000, the model predicted an amount of E. coli transported from water of intermediate depth, where sediment resuspension occurred intermittently, that would be sufficient to have elevated E. coli concentration in the surf and swash zones as observed. The nighttime replenishment of E. coli in the surf and swash zones revealed here is an important phase in the cycle of diel variations of E. coli concentration in nearshore water. According to previous findings in Ge et al. (Environ. Sci. Technol. 2010, 44, 6731–6737), enhanced current circulation in the embayment during the day tends to displace and deposit material offshore, which partially sets up the system by the early evening for a new period of nighttime onshore movement. This wave-induced mass transport effect, although facilitating a significant base supply of material shoreward, can be perturbed or significantly influenced by high currents (orders of magnitude larger than a typical wave-induced mass transport velocity), current-induced turbulence, and tidal forcing.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water
Series title:
Environmental Science and Technology
DOI:
10.1021/es203847n
Volume
46
Issue:
4
Year Published:
2012
Language:
English
Publisher:
ACS Publications
Publisher location:
Washington, D.C.
Contributing office(s):
Great Lakes Science Center
Description:
8 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
2204
Last page:
2211
Country:
United States
State:
Illinois
City:
Chicago
Other Geospatial:
63rd Street Beach