State Water Resources Research Institute Program

Project ID: 2009IL173B
Title: Attachement and Transport Mechanisms of Cryptosporidium parvum Oocysts in Subsurface Environments: A Multi-Scale Study
Project Type: Research
Start Date: 5/01/2009
End Date: 4/30/2010
Congressional District: 15
Focus Categories: Water Quantity, Groundwater, Agriculture
Keywords: pathogen transport, groundwater contamination, manure
Principal Investigator: Nguyen, Helen; Liu, Yuanyuan
Federal Funds: $ 33,807
Non-Federal Matching Funds: $ 67,616
Abstract: Pathogens including Cryptosporidium parvum oocysts found in surface runoff are one of the leading causes of impaired river and estuary water. Over one million cattles are able to produce approximately 8000 oocysts annually for every person in the state of Illinois. This number of oocysts far exceeds the infectious dose for humans. Knowledge on the fate and transport of C. parvum oocysts in agricultural runoff is currently lacking and is urgently needed to protect water supplies for many parts of the state. The introduction of pathogenic oocysts to subsurface environments is of major concern as groundwater is a primary source of drinking water in Illinois. The results of this project will provide a scientific basis for water resources and environmental sustainability.

This project uses a multi-scale approach to identify chemical and physical factors that influence attachment and mobility of C. parvum oocysts. A comprehensive understanding of these factors will be used to develop a model to predict the fate and transport of oocysts in the subsurface environment. The objectives of this project are: (1) to investigate the role of oocyst wall macromolecules in the deposition and transport of C. parvum oocysts by systematically modifying the oocyst wall; (2) to determine the attachment mechanisms of C. parvum oocysts on inorganic (i.e. quartz) and organic (i.e. coated with natural organic matter) soil surfaces on a microscopic scale; and (3) to determine the transport of C. parvum oocysts in the subsurface environment in micromodel and column setups. The experimental approach ranges from a microscopic to a macroscopic scale. A novel microscopic technique consisting of a radial stagnation point flow (RSPF) cell combined with a microscope will be used to monitor attachment and detachment kinetics of oocysts under well-defined flow conditions in real time. Deposition and detachment experiments will be conducted with systematically varied solution conditions to determine the mechanisms of oocyst interaction with representative soil surfaces. Pore scale transport of oocysts will be studied using a precisely fabricated micromodel. Knowledge on oocyst deposition and transport at the microscale will be applied to elucidate transport at the continuum scale of column setup.

The main hypothesis of this project is that reversibility of oocyst deposition and subsequent transport depends on the composition of pore-water. Water contaminated with manure has significantly higher salt and organic matter than clean water such as rain. A significant portion of oocysts deposited on soil surfaces in solutions with ionic strengths ranging from 3-30 mM is expected to detach during a sudden drop in ionic strength due to rain fall. Mobilization of the previously attached oocysts provides an additional rapid transport pathway of pathogens to water source. This hypothesis will be tested using both deposition experiments in a RSPF and transport experiments in a micromodel and column setup.

This project will provide partial support to Ms. Yuanyuan Liu, a doctoral student in the Environmental Engineering and Science program at the University of Illinois at Urbana-Champaign. Under the supervision of the PI, Ms. Liu has submitted a manuscript to Langmuir journal based on the results obtained during her first year of research on deposition kinetics of oocysts on natural organic matter. The funding from IWCR is critical to extend our preliminary research and at the same time generate new knowledge necessary for a long-term research program focused on controlling and monitoring pathogens for water resources.

Progress/Completion Report, 2009, PDF

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