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United States Department of Agriculture

Agricultural Research Service

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Location: Contaminant Fate and Transport Research

2013 Annual Report

1a. Objectives (from AD-416):
The overall objective of this project is to improve our understanding of and ability to predict the transport and fate of pathogenic microorganisms at various spatial scales (from pore to plot scale).

1b. Approach (from AD-416):
Laboratory experiments will be designed to test specific hypotheses with regard to mechanisms controlling pathogen transport and fate in the environment. The specific experimental approaches and techniques will depend on the research question. For example, we may use measurements of electrophoretic mobility, hydrophobicity, surface charge density, enzyme treatment, FTIR, and TEM imaging to examine surface properties of pathogens that influence their interaction in the environment. We may use batch, micromodel systems, DLVO calculations, pore-scale flow and transport simulation techniques, and saturated and unsaturated column experiments to examine mechanisms of pathogen transport, retention, and survival. Information collected from laboratory studies will be used to refine and improve the predictions of models for pathogen transport and fate. Existing models for pathogen transport and survival will be modified to simulate field scale behavior. Documents SCA with UC Riverside. Formerly 5310-32000-002-10S(8/11/11).

3. Progress Report:
Laboratory and numerical studies were conducted to investigate the transport and fate of microbes (E.coli D21g and/or coliphage fX174) in saturated soils with preferential flow. Different macropore lengths and configurations, and solution iconic strength conditions were considered in these experiments. The importance of preferential flow on microbe transport increased with the solution iconic strength, and the macropore length and continuity. Furthermore, E. coli D21g exhibited greater preferential transport than fX174. A variety of modeling approaches were examined to simulate the observed preferential transport behavior (e.g., 2D deterministic model and 1D dual permeability model). The objectives of the SCA and parent project complement each other. For example, objective three of the parent project, "Develop management practices to minimize the transport of pathogens from concentrated dairy and beef cattle operations to water resources" directly relates to our experiments examining pathogen transport during overland flow. Preferential transport of pathogens will also occur during overland flow and this has been studied as part of the SCA research described above.

4. Accomplishments

Last Modified: 05/23/2017
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