Role of Manure Application on Soil in Preventing Groundwater Contamination by Cryptosporidium

Livestock are reservoirs of human pathogenic Cryptosporidium species and fertilizing fields with livestock manure can result in cryptosporidiosis outbreaks. Significant amounts of Cryptosporidium can reach groundwater by infiltrating through the manure applied soil. To quantify and predict the transport of cryptosporidium in groundwater aquifers, it is essential to understand the interaction between the oocysts and soil particles. The main objective of this study was to investigate adsorption of Cryptosporidium parvum on natural soil by performing isotherm experiments with different types of soil. The role of manure application on soil was the focus of the study. Without manure, very slightly higher adsorption of Cryptosporidium to the clayey soil (1.94×105 to 1.75×106) compared to the loam soil (1.92×105 to 1.68×106) was observed. Good fit of the experimental data to Freundlich or Redlich-Perterson isotherm suggests a role of non-specific physical forces involved in the adsorption of oocysts. With manure, the adsorption of Cryptosporidium to the rocky sand increased by 35.2%-36.2%, while for the loam and clayey soil, the increases in adsorption were minimal, 2.3%- 2.6% and 1.3%-1.5%, respectively. The adsorption parameters identified in this study are of great significance for establishing models which can be used in laboratory and field studies of Cryptosporidium transport in soil.