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Title: Modeling microorganism transport and survival in the subsurface

Author
item Bradford, Scott
item WANG, YUSONG - University Of California
item KIM, HYUNJUNG - Chonbuk National University
item TORKZABAN, SAEED - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item SIMUNEK, JIRI - University Of California

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2013
Publication Date: 6/23/2014
Citation: Bradford, S.A., Wang, Y., Kim, H., Torkzaban, S., Simunek, J. 2014. Modeling microorganism transport and survival in the subsurface. Journal of Environmental Quality. 43(2):421-440.

Interpretive Summary: Mathematical models can be useful tools to help understand and predict the complexities of microbial transport and survival in soils and aquifers. This information is critical for improving many industrial and environmental applications. This paper highlights existing microbial transport and survival models, and then demonstrates their ability to simulate the fate of E.coli species under a variety of environmentally relevant scenarios. Results demonstrate challenges and limitations of models to describe and predict microbial fate. In general, model parameters may be optimized to simulate a diversity of observed behavior. Improved methods are needed to predict model parameters in natural systems. This information will be of interest to scientists, engineers, and regulators that are concerned with the fate of microorganisms in the environment.

Technical Abstract: An understanding of microbial transport and survival in the subsurface is needed for public health, environmental applications, and industrial processes. Much research has therefore been directed to quantify mechanisms influencing microbial fate, and the results demonstrate a complex coupling among many physical, chemical, and biological factors. Mathematical models can be used to help understand and predict the complexities of microbial transport and survival in the subsurface under given assumptions and conditions. This review highlights existing model formulations that can be used for this purpose. In particular, we discuss models based on the advection–dispersion equation, with terms for kinetic retention to solid–water and/or air–water interfaces; blocking and ripening; release that is dependent on the resident time, diffusion, and transients in solution chemistry, water velocity, and water saturation; and microbial decay (first-order and Weibull) and growth (logistic and Monod) that is dependent on temperature, nutrient concentration, and/or microbial concentration. We highlight a two-region model to account for microbe migration in the vicinity of a solid phase and use it to simulate the coupled transport and survival of Escherichia coli species under a variety of environmentally relevant scenarios. This review identifies challenges and limitations of models to describe and predict microbial transport and survival. In particular, many model parameters have to be optimized to simulate a diversity of observed transport, retention, and survival behavior at the laboratory scale. Improved theory and models are needed to predict the fate of microorganisms in natural subsurface systems that are highly dynamic and heterogeneous.