Transport of Escherichia coli through a Thick Vadose Zone

Abstract

Livestock manure applications on fields can be a source of contamination in water resources, including groundwater. Although fecal indicators like have often been detected in tile drainage systems, few studies have monitored groundwater at depth after manure treatments, especially at sites with a deep, heterogeneous vadose zone. Our hypothesis was that microbial transport through a thick vadose zone would be limited or nonexistent due to attenuation processes, subsurface thickness, and heterogeneity. This study tested this hypothesis by monitoring concentrations beneath a 12-m-thick vadose zone of coarse, heterogeneous glacial sediments after surface application of liquid swine manure. was detected on all 23 sample dates over the 5-mo period (4 Apr. 2012-13 Aug. 2012), with particularly elevated concentrations 1 wk after application and lasting for 5 wk. Variable low-level concentrations before and after the elevated period suggest remobilization and delayed transport of microorganisms to the water table without additional loadings within the flow field. These findings suggest preferential flow pathways allowing deep infiltration of manure bacteria as well as a continued source of bacteria, with variable retention and travel times, over several months. Preferential flow pathways at this site include soil macropores, depression focused infiltration, and pathways related to subsurface heterogeneity and/or fracture flow through finer-grained diamict beds. Further research is needed to confirm the relative contribution of sources, constrain travel times, and define specific transport pathways.

Seasonality of Coliform Bacteria Detection Rates in New Jersey Domestic Wells

“…As septic tank disposal field laterals are only 9 to 18 inches (23 to 46 cm) below the ground surface (New Jersey Administrative Code 2012), fecal-derived coliforms from septic tank leach fields (Arnade 1999) could also undergo temperatureinduced changes in concentrations. The indigenous or non-fecal sources include coliform residents of soils (Van Donsel et al 1967;Ishii et al 2006;Arnaud et al 2015), sediments (Crabill et al 1999), and coliforms contained within biofilms in surface or near-surface rock strata, and within fractures in grout and micro-annuli between the grout and well casing (Ross 2010;Kozuskanich et al 2011;Somaratne and Hallas 2015).…”

Preferential flow paths shape the structure of bacterial communities in a clayey till depth profile

“…2010; Arnaud et al . 2015). However, the extent of this anticipated transport of microorganisms from topsoil to lower fractures remains unknown.…”

Fate of Manure‐Borne Pathogens during Anaerobic Digestion and Solids Separation

“…However, the majority of this manure-520 Tg yr −1 in the United States (USEPA, 2013)-typically undergoes little to no treatment prior to land application. Thus, it can contaminate surface water (Corsi et al, 2014) and groundwater (Arnaud et al, 2015) with zoonotic pathogens via runoff and infiltration, respectively. This contamination with zoonotic pathogens can, in turn, spread waterborne disease to humans through both recreational and drinking water (USDA, 2012).…”