Numerical Modeling of Microbial Fate and Transport in Natural Waters: Review and Implications for Normal and Extreme Storm Events

Chelsea J Weiskerger,Mantha S Phanikumar

doi:10.3390/w12071876

Abstract

Degradation of water quality in recreational areas can be a substantial public health concern. Models can help beach managers make contemporaneous decisions to protect public health at recreational areas, via the use of microbial fate and transport simulation. Approaches to modeling microbial fate and transport vary widely in response to local hydrometeorological contexts, but many parameterizations include terms for base mortality, solar inactivation, and sedimentation of microbial contaminants. Models using these parameterizations can predict up to 87% of variation in observed microbial concentrations in nearshore water, with root mean squared errors ranging from 0.41 to 5.37 log10 Colony Forming Units (CFU) 100 mL−1. This indicates that some models predict microbial fate and transport more reliably than others and that there remains room for model improvement across the board. Model refinement will be integral to microbial fate and transport simulation in the face of less readily observable processes affecting water quality in nearshore areas. Management of contamination phenomena such as the release of storm-associated river plumes and the exchange of contaminants between water and sand at the beach can benefit greatly from optimized fate and transport modeling in the absence of directly observable data.

Highlights

Water systems and the recreational opportunities that they afford bring millions of people outside each year, especially during warm weather
Over 75% of people traveling in the summer visit beaches, and in Chicago alone 20 million people go to Lake Michigan beaches annually, on average [1,2]
This monitoring, often involves obtaining samples and either culturing for fecal indicator organisms (FIO) such as E. coli or enterococci or using quantitative Polymerase Chain Reactions to determine FIO concentrations in the water. These approaches take time, leading to a delay of up to 24 hours before obtaining water quality information to effectively manage beach usage for public health. This delay can be the difference between keeping beachgoers safe by advising against beach access and putting them in danger by keeping a contaminated beach open for recreation

Summary

Introduction

Water systems and the recreational opportunities that they afford bring millions of people outside each year, especially during warm weather. To protect public health and the safety of beachgoers, the Beaches Environmental Assessment and Coastal Health (BEACH) Act of 2000 requires routine monitoring of coastal water quality at both marine and freshwater beaches across the USA [3] This monitoring, often involves obtaining samples and either culturing for fecal indicator organisms (FIO) such as E. coli or enterococci or using quantitative Polymerase Chain Reactions (qPCR) to determine FIO concentrations in the water. These approaches take time, leading to a delay of up to 24 hours before obtaining water quality information to effectively manage beach usage for public health. This delay can be the difference between keeping beachgoers safe by advising against beach access and putting them in danger by keeping a contaminated beach open for recreation

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