title: Effect of Low Energy Waves on the Accumulation and Transport of Fecal Indicator Bacteria in Sand and Pore Water at Freshwater Beaches.
abstract: Elevated fecal indicator bacteria (FIB) in beach sand and pore water represent an important nonpoint source of contamination to surface waters. This study examines the physical processes governing the accumulation and distribution of FIB in a beach aquifer. Field data indicate E. coli and enterococci can be transported 1 and 2 m, respectively, below the water table. Data were used to calibrate a numerical model whereby FIB are delivered to a beach aquifer by wave-induced infiltration across the beach face. Simulations indicate FIB rapidly accumulate in a beach aquifer with FIB primarily associated with sand rather than freely residing in the pore water. Simulated transport of E. coli in a beach aquifer is complex and does not correlate with conservative tracer transport. Beaches with higher wave-induced infiltration rate and vertical infiltration velocity (i.e., beaches with higher beach slope and wave height, and lower terrestrial groundwater discharge) had greater E. coli accumulation and E. coli was transported deeper below the beach face. For certain beach conditions, the amount of FIB accumulated in sand over 5-6 days was found to be sufficient to trigger a beach advisory if eroded to surface water.
authors.affiliation: Department of Civil and Environmental Engineering, Western University , London ON, Canada N6A 5B9.
authors.forename: Ming Zhi
authors.initials: MZ
authors.lastname: Wu
authors.affiliation: Department of Civil and Environmental Engineering, Western University , London ON, Canada N6A 5B9.|School of Civil and Environmental Engineering, Connected Water Initiative, University of New South Wales , Manly Vale NSW 2093, Australia.
authors.forename: Denis M
authors.identifier: 0000-0001-6557-226X
authors.initials: DM
authors.lastname: O'Carroll
authors.affiliation: Department of Civil and Environmental Engineering, Western University , London ON, Canada N6A 5B9.
authors.forename: Laura J
authors.identifier: 0000-0003-0501-7242
authors.initials: LJ
authors.lastname: Vogel
authors.affiliation: Department of Civil and Environmental Engineering, Western University , London ON, Canada N6A 5B9.
authors.forename: Clare E
authors.identifier: 0000-0002-6156-2328
authors.initials: CE
authors.lastname: Robinson
mesh_terms: D001419:Bacteria; D001493:Bathing Beaches; D016983:Enterococcus; D004926:Escherichia coli; D005243:Feces / Q000382:microbiology; D005618:Fresh Water / Q000382:microbiology; D014867:Water; D014871:Water Microbiology
chemical_list: D014867:Water