title: Using microbiological tracers to assess the impact of winter land use restrictions on the quality of stream headwaters in a small catchment.
abstract: Diverse land use activities can elevate risk of microbiological contamination entering stream headwaters. Spatially distributed water quality monitoring carried out across a 17 km(2) agricultural catchment aimed to characterize microbiological contamination reaching surface water and investigate whether winter agricultural land use restrictions proved effective in addressing water quality degradation. Combined flow and concentration data revealed no significant difference in fecal indicator organism (FIO) fluxes in base flow samples collected during the open and prohibited periods for spreading organic fertilizer, while relative concentrations of Escherichia coli, fecal streptococci and sulfite reducing bacteria indicated consistently fresh fecal pollution reached aquatic receptors during both periods. Microbial source tracking, employing Bacteroides 16S rRNA gene markers, demonstrated a dominance of bovine fecal waste in river water samples upstream of a wastewater treatment plant discharge during open periods. This contrasted with responses during prohibited periods where human-derived signatures dominated. Differences in microbiological signature, when viewed with hydrological data, suggested that increasing groundwater levels restricted vertical infiltration of effluent from on-site wastewater treatment systems and diverted it to drains and surface water. Study results reflect seasonality of contaminant inputs, while suggesting winter land use restrictions can be effective in limiting impacts of agricultural wastes to base flow water quality.
authors.affiliation: School of Planning, Architecture and Civil Engineering, The Queen's University of Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, Northern Ireland, United Kingdom. Electronic address: r.flynn@qub.ac.uk.
authors.forename: Raymond M
authors.initials: RM
authors.lastname: Flynn
authors.affiliation: Environmental Protection Agency, Richview, Clonskeagh, Dublin 14, Ireland; Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Jenny
authors.initials: J
authors.lastname: Deakin
authors.affiliation: Microbiology, School of Natural Sciences, Ryan Institute, NUI, Galway, University Road, Galway, Ireland.
authors.forename: Marie
authors.initials: M
authors.lastname: Archbold
authors.affiliation: School of Planning, Architecture and Civil Engineering, The Queen's University of Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, Northern Ireland, United Kingdom.
authors.forename: Hugh
authors.initials: H
authors.lastname: Cushnan
authors.affiliation: Microbiology, School of Natural Sciences, Ryan Institute, NUI, Galway, University Road, Galway, Ireland.
authors.forename: Kate
authors.initials: K
authors.lastname: Kilroy
authors.affiliation: Microbiology, School of Natural Sciences, Ryan Institute, NUI, Galway, University Road, Galway, Ireland.
authors.forename: Vincent
authors.initials: V
authors.lastname: O'Flaherty
authors.affiliation: Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Misstear
mesh_terms: D000383:Agriculture / Q000331:legislation & jurisprudence / Q000379:methods*; D000818:Animals; D002417:Cattle; D004784:Environmental Monitoring; D058735:Environmental Policy; D006801:Humans; D045483:Rivers / Q000382:microbiology*; D012621:Seasons; D014876:Water Pollution / Q000032:analysis* / Q000706:statistics & numerical data
keywords: Hydrological pathways; Microbial source tracking; Pathogenic microorganisms; Seasonality; Water quality