The University of Arizona
SWES dept logo Environmental Biogeochemistry Group Sabino Canyon in fall color
Department of Soil, Water and Environmental Science

Research Project:

Influence of Soluble Organic Matter on Cryptosporidium Oocyst Mobility in Variable Charge Soils

Oocysts, the environmental form of the protozoan pathogen Cryptosporidium parvum, can pose a serious threat to drinking water sources because of their ubiquity, environmental persistence, high resistance to chemical disinfection, and the low numbers needed to cause disease. In many areas of the United States, livestock animals are the major source of C. parvum and sorption to soil particles is the primary mechanism limiting the introduction of this pathogen into source waters. Very little information is available on the transport and attachment behaviors of oocysts in soils characterized by variable charge surfaces that are common to vast areas of the southeastern U.S., Hawaii, and Puerto Rico. The main objective of this research is to provide information needed to how effectively and by what mechanisms C. parvum oocysts are immobilized in watersheds containing by variable charge soils and how the immobilization is impacted by dissolved and co-sorbing organic matter and particle surface chemistry. This project will employ FTIR micro-spectroscopy methods under development in our lab.

Group Contacts:
Jon Chorover and Xiaodong Gao  


Dr. Chittaranjan Ray (University of Hawaii)
Dr. Ronald Harvey (USGS Boulder, CO)  

Funding Source:

USDA, National Research Initiative, Water and Watersheds Program  

Selected Project References (click here for full publication list):

  • Gao, X. D., and J. Chorover. 2009. In-situ monitoring of Cryptosporidium parvum ÷ocyst surface adhesion using ATR-FTIR spectroscopy. Colloids Surf. B: Biointerfaces 71, 169-176.

  • Gao, X. D., D. W. Metge, C. Ray, R. Harvey, and J. Chorover. 2009. Surface complexation of carboxylate adheres Cryptosporidium parvum ÷ocysts to the hematite-water interface. Environ. Sci. Technol. 43, 7423-7429.

  • Gao, X. D.; Chorover, J. Adsorption of sodium dodecylsulfate (SDS) at ZnSe and a-Fe2O3 surfaces: Combining infrared spectroscopy and batch uptake studies. J. Colloid Interface Sci. 2010, 348, 167-176.

  • Gao, X., and J. Chorover. 2010. Amphiphile disruption of pathogen attachment at the hematite (a-Fe2O3)-water interface. In review




Updated November 18, 2010

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