Submitted to: Pathogens in the Environment Workshop Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2004
Publication Date: 2/23/2004
Citation: Pachepsky, Y.A., Bradford, S.A., Sadeghi, A.M., Guber, A.K., Shelton, D.R. 2004. Modeling fate and transport of manure-borne pathogens in the environment. In: Proceedings of the Pathogens in the Environment Workshop, February 23-25, 2004, Kansas City, Missouri. p. 34-38. Interpretive Summary: The purpose of this work is to review the status and the research needs of the pathogen water transport modeling. At core and pedon scales, modeling serves a research tool to test hypotheses about mechanisms and factors of pathogen transport and fate. At hillslope and watershed scales, modeling serves as a knowledge packaging and delivery tool to address issues of public concern. The pathogen fate and transport (PFT) modeling greatly depends on correct representation of water transport in models, as water serves as a carrier and a milieu. Fundamental processes that need to be represented in PFT models include release of pathogens from manure to flowing water, interactions of pathogens, manure particles, and clays, partitioning of pathogens from water to soil and sediment particles, and plants, and inactivation due to environmental conditions and biotic effects. Transport of manure-borne microorganisms has to be studied, simulated and mitigated with explicit simulation of manure being a carrier, an abode, and a food source for pathogens. Modeling is an important tool for designing vegetated buffer strips. Several models have been developed and applied to estimate manure-borne pathogen transport at the watershed scale. None of the models has a pathogen-specific parameter database to date. Deriving those parameters by upscaling from field plots and hillslopes may be more feasible in terms of gathering experimental data. Many pathogen fate and transport models exist and coexist, and a work on model intercomparison seems to be needed.
Technical Abstract: Pathogen dissemination pathways in the environment include water transport, aerial transport, produce, and movement of organisms-carriers. The purpose of this talk is to review the status and the research needs of the pathogen water transport modeling. The majority of published PFT models at the soil core scale are only partly applicable to microbial leaching from either land-applied or naturally deposited manures. Our data indicate that transport of manure-borne microorganisms has to be studied, simulated and mitigated as the colloid-facilitated transport. The field plot/pedon scale presents a special interest for modeling because this scale is relevant to the design of vegetated buffer strips, efficiency of which with respect of manure-borne pathogen retention remains controversial. We found a simple kinematic wave-based transport model to be applicable to the bacteria transport both in runoff and with infiltrating water, although modeling for vegetated strips with layered soil requires more details in simulations of the soil water transport. Further studies are needed to elucidate manure and microorganism release factors. None of the many models developed for the watershed scale has a pathogen-specific database to date, and none of the models has a tested module of fate and transport of pathogens in surface water. We pursue the research direction based on the upscaling with a compulsory representation of preferential pathway at fine scale. The complexity of flow pathways and pathogen transport mechanisms implies that many pathogen fate and transport models can exist and coexist. Model intercomparison is needed.