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Budget analysis of Escherichia coli at a southern Lake Michigan Beach

Environmental Science and Technology

By:
, , , , ,
DOI: 10.1021/es902232a

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Abstract

Escherichia coli (EC) concentrations at two beaches impacted by river plume dynamics in southern Lake Michigan were analyzed using three-dimensional hydrodynamic and transport models. The relative importance of various physical and biological processes influencing the fate and transport of EC were examined via budget analysis and a first-order sensitivity analysis of model parameters. The along-shore advective fluxofEC(CFU/m2·s)was found to be higher compared to its crossshore counterpart; however, the sum of diffusive and advective components was of a comparable magnitude in both directions showing the importance of cross-shore exchange in EC transport. Examination of individual terms in the EC mass balance equation showed that vertical turbulent mixing in the water column dominated the overall EC transport for the summer conditions simulated. Dilution due to advection and diffusion accounted for a large portion of the total EC budget in the nearshore, and the net EC loss rate within the water column (CFU/m3·s) was an order of magnitude smaller compared to the horizontal and vertical transport rates. This result has important implications for modeling EC at recreational beaches; however, the assessment of the magnitude of EC loss rate is complicated due to the strong coupling between vertical exchange and depth-dependent EC loss processes such as sunlight inactivation and settling. Sensitivity analysis indicated that solar inactivation has the greatest impact on EC loss rates. Although these results are site-specific, they clearly bring out the relative importance of various processes involved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Budget analysis of Escherichia coli at a southern Lake Michigan Beach
Series title:
Environmental Science and Technology
DOI:
10.1021/es902232a
Volume
44
Issue:
3
Year Published:
2010
Language:
English
Publisher:
ACS Publications (American Chemical Society)
Publisher location:
Washington, D.C.
Contributing office(s):
Lake Michigan Ecological Research Station
Description:
7 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1010
Last page:
1016
Country:
United States