Location: Contaminant Fate and Transport ResearchTitle: Transport and fate of microbial pathogens in agricultural settings Author
Submitted to: Critical Reviews in Environmental Science Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2013
Publication Date: 2/27/2013
Publication URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2370.pdf
Citation: Bradford, S.A., Morales, V.L., Zhang, W., Harvey, R.W., Packman, A.I., Mohanram, A., Welty, C. 2013. Transport and fate of microbial pathogens in agricultural settings. Critical Reviews in Environmental Science Technology. 43(8):775-893. Interpretive Summary: An understanding of the transport and survival of microbial pathogens in agricultural settings is needed to assess the risk of pathogen contamination to water and food resources, and to develop control strategies and treatment options. However, many gaps in knowledge still remain in predicting the fate and transport of pathogens in runoff water, through the shallow unsaturated vadose zone and saturated groundwater. This review summarizes current approaches, potential benefits, and challenges to understanding pathogen transport and fate in agricultural settings at various scales, and provides a conceptual and mathematical framework to address these issues. This information will be of interest to scientists and engineers concerned with the transport and fate of pathogens in soils, groundwater, runoff water, and on fresh produce.
Technical Abstract: An understanding of the transport and survival of microbial pathogens (pathogens hereafter) in agricultural settings is needed to assess the risk of pathogen contamination to water and food resources, and to develop control strategies and treatment options. However, many knowledge gaps still remain in predicting the fate and transport of pathogens in runoff water, and then through the shallow vadose zone and groundwater. A number of transport pathways, processes, factors, and mathematical models often are needed to describe pathogen fate in agricultural settings. The level of complexity is dramatically enhanced by soil heterogeneity, as well as by temporal variability in temperature, water inputs, and pathogen sources. There is substantial variability in pathogen migration pathways, leading to changes in the dominant processes that control pathogen transport over different spatial and temporal scales. For example, intense rainfall events can generate runoff and preferential flow that can rapidly transport pathogens. Pathogens that survive for extended periods of time have a greatly enhanced probability of remaining viable when subjected to such rapid-transport events. Conversely, in dry seasons, pathogen transport depends more strongly on retention at diverse environmental surfaces controlled by a multitude of coupled physical, chemical, and microbiological factors. These interactions are incompletely characterized, leading to a lack of consensus on the proper mathematical framework to model pathogen transport even at the column scale. In addition, little is known about how to quantify transport and survival parameters at the scale of agricultural fields or watersheds. This review summarizes current conceptual and quantitative models for pathogen transport and fate in agricultural settings over a wide range of spatial and temporal scales. The authors also discuss the benefits that can be realized by improved modeling, and potential treatments to mitigate the risk of waterborne disease transmission.