Fate and transport of Cryptosporidium parvum oocysts in repacked soil columns: Influence of soil properties and surfactant

A series of laboratory experiments was performed to investigate the transport and retention of viable C. parvum oocysts in soil columns homogeneously packed with loamy sand soils (Lewiston and Greenson series) and sandy loam soils (Sparta and Gilford series), and under hydrologic conditions involving the presence of an anionic surfactant-Aerosol 22 in artificial rainfall. To characterize the effect of surfactant on the mobility of C. parvum oocysts in the soils used in this study, these results were compared with previous laboratory-scale column experiments of a previous study using soils contaminated with oocysts, under conditions identical to those described here except for the absence of the surfactant in the percolating water. Quantitative polymerase chain reaction was used for the detection and quantification of C. parvum oocysts in soil leachates to assess their breakthrough and in soil matrices to characterize their spatial distribution. Alterations in the rate and extent of transport of C. parvum oocysts were discerned per the physicochemical parameters analyzed-soil types, soil chemistry, and surfactant-and resulted in either the enhancement or hinderance of C. parvum oocysts adsorption to surfaces, and their movement in soils. In the case of loamy sand soils, the transport of C. parvum oocysts through the soil matrices increased with the application of surfactant for Sparta series and remained at a similar level for Gilford series. Regarding sandy loam soils, the movement of C. parvum oocysts through the soil matrices increased for Greenson series and decreased for Lewiston series with the application of surfactant.