Date of Award

12-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Engineering and Earth Sciences

Committee Member

Dr. Christophe Darnault, Committee Chair

Committee Member

Dr. Kevin Finneran

Committee Member

Dr. David Ladner

Abstract

Toxoplasma gondii is among the most prevalent parasites affecting warm-blooded animals, including humans. In humans, it poses health risks for immunocompromised populations and for fetuses including damage to the eyes brain and other organs. Humans may come in contact with T. gondii through the consumption of infected animal flesh or accidental contact with cat feces. Its life cycle includes numerous intermediate hosts and felids as the definitive host, which has allowed for its spread through nearly the entire world. T. gondii has been detected in open water, soil and animal feeds. Its transport has not been well studied to this point. Understanding of transport of T. gondii is necessitated by its presence in soils and human health risks. Surfactants may be introduced in agricultural settings through the application of reused water and sludge to fields, through environmental remediation or the use of pesticides that include surfactants. Surfactants may influence water flow and soil hydrology properties, impacting the flow of water and pathogens conveyed within it. The aim of this study is to assess the way the presence of surfactant influences the transport of T. gondii through soil. Continuous rainfall of a KCl solution was simulated on columns of sandy loam and loamy sand soils. Flow within the columns was vertical and gravity driven. Artificial rain on select columns contained an anionic surfactant, Aerosol 22. After steady state was reached, a pulse containing T. gondii oocysts and KBr as a tracer was applied. In those columns where Aerosol 22 was included in the rain, it was also present in the pulses. T. gondii and KBr breakthrough curves were created to characterize transport. Following cessation of the simulated rainfall, soil columns were cut to assess retention of the oocysts within the soil and concentrations of oocysts are given by depth. For both soil and leachate samples, T. gondii was quantified using qPCR. Toxoplasma gondii oocysts were detected in all columns retained in porous media and in leachate. Surfactant was shown to enhance transport in all soil series studied.

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