ROLE OF MINERALOGY AND DISSOLVED ORGANIC CARBON on THE REMOVAL OF CRYPTOSPORIDIUM PARVUM OOCYSTS AND OOCYSTS SURROGATES IN DISPARATE AGRICULTURAL SOILS

The World Health Organization reports that the primary cause of death among children is due to contamination of drinking water by waterborne pathogens like Cryptosporidium parvum oocysts. Farm animals are often the reservoirs of oocysts and the regions surrounding agricultural activities are sources of dissolved organic carbon (DOC). Oocysts from the manure can contaminate surface and ground water in response to rainfall events by migration over or through soils. Flow-through column experiments were conducted to study the movement of C.parvum oocysts and microspheres through two disparate agriculture soils. The “Poamoho” soil, from the island of Oahu is of volcanic origin that has undergone intense weathering. Consequently, it has a very high metal oxide (32%) and clay content (68%) . The much younger “Lalamilo soil”, derived from volcanic ashes of the island of Hawaii, is comparatively fine-grained with a high soil organic matter (43%) and metal oxides (57%) content. A third agricultural “Drummer“ soil from Illinois that is rich in organic matter (13%) and quartz (40%) was used as a reference. Oocyst transport occurred through preferential flow paths in Poamoho and Drummer soil. However, 2-µm microsphere exhibited high degrees of reversible attachment in Lalamilo soil. Amendments of Poamoho and Drummer soils clays or 4mg/L Suwannee River humic acid substantively increased the negative charge of the oocysts but not the 2-µm microspheres. These studies indicate that it is necessary to take the individual soil properties into account when predicting the movement of oocysts through the subsurfaces. Also, the presence of DOC can substantively modify the manner in which pathogens and microspheres interact with the granular media.