Subsurface Transport of in Soils of Wisconsin's Carbonate Aquifer Region.

Abstract

is a waterborne pathogen known to have a significant reservoir in bovine manure. Land-dependent manure disposal may not result in significant or reliable pathogen attenuation and, therefore, presents a risk for transport of pathogenic spp. to groundwater. One factor missing in the existing literature is the role soil characteristics play in affecting oocyst transport. Of specific concern in regions with carbonate geology are macropores and other soil structures that contribute to preferential flow. Therefore, research is needed to understand soil type effects and important transport pathways for pathogens such as oocysts to drinking water wells. This study investigated transport potential in several soils overlying Wisconsin's vulnerable carbonate aquifer and related the soil transport to soil series and textural class. Experimental work involved monitoring the transport of oocysts through intact soil columns of different soil series under simulated rain conditions. Results demonstrate that a significant portion of oocysts will sorb or be physically entrapped in the soil, especially in soil with high clay content. However, silt loam soils with comparatively lower clay content demonstrated an ability to transport oocysts through the soil profile primarily via the first flush of water infiltrating through soil macropores. The rate of oocyst migration in silt loam soils paralleled the bromide tracer front, thus bypassing the soils' ability to strain or adsorb oocysts out of infiltrating water. Nevertheless, proper manure treatment and management are necessary to minimize public health risks.