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Title: Future research needs involving pathogens in groundwater

item Bradford, Scott
item HARVEY, RONALD - Us Geological Survey (USGS)

Submitted to: Hydrogeology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2016
Publication Date: 12/2/2016
Citation: Bradford, S.A., Harvey, R.W. 2016. Future research needs involving pathogens in groundwater. Hydrogeology Journal. 24(4):1-8. doi: 10.1007/s.10040-016-1501-0.

Interpretive Summary: Groundwater contamination by pathogenic microorganisms has led to a number of food- and water-borne disease outbreaks, and there is concern that the risk of pathogen contamination to groundwater may increase in the future because of ever-increasing demand for potable groundwater, extreme weather events associated with climate change, land use alterations and ecological disturbances, emerging infectious diseases, and the proliferation of managed aquifer recharge and on-land waste disposal. The purpose of this invited essay is to identify and discuss existing knowledge gaps and potential directions for future studies involving the transport and fate of pathogens in groundwater. This essay is divided into the following topic sections: Sources; Detection; Indicators; Emerging Issues; Retention and Release; Survival; and Mathematical Modeling. In each section we provide a brief review of the literature and then identify critical knowledge gaps that need to be overcome in order to better protect groundwater from pathogen contamination.

Technical Abstract: Contamination of groundwater by enteric pathogens has commonly been associated with disease outbreaks. Proper management and treatment of pathogen sources are important barriers to preventing groundwater contamination. However, non-point sources of pathogen contamination are frequently difficult to identify and existing detection approaches are costly and only provide semi-quantitative information. Easily measured microbial indicators frequently exhibit little correlation with pathogen concentrations or their environmental fate, and new pathogens and antibiotic resistant bacteria are topics of emerging concern. Adequate removal of pathogens during soil passage is therefore critical for safe groundwater production. Processes that enhance pathogen transport (e.g., high velocity zones) and diminish pathogen removal (e.g., reversible retention and enhanced survival) are of special concern because they increase the risk of groundwater contamination, but are still incompletely quantified. Improved theory and modeling tools are needed to analyze experimental data, test hypotheses, understand coupled processes and controlling mechanisms, predict spatial and/or temporal variability in model parameters and uncertainty in pathogen concentrations, assess risk, and develop mitigation and best management approaches to protect groundwater.