Modeling the photoinactivation and transport of somatic and F-specific coliphages at a great lakes beach

Authors: SAFAIE, AMMAR - Michigan State University; NGUEN, TUAN - Michigan State University; WEISKERGER, CHELSEA - Michigan State University; ACREY, BRAD - Us Environmental Protection Agency (EPA); ZEPP, RICHARD - National Exposure Research Laboratory (NERL); MOLINA, MARIROSA - National Exposure Research Laboratory (NERL); CYTERSKI, MICHAEL - National Exposure Research Laboratory (NERL); WHELAN, GENE - National Exposure Research Laboratory (NERL); Pachepsky, Yakov; PHANIKUMAR, MANTHA - Michigan State University

Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2020
Publication Date: 11/30/2020
Citation: Safaie, A., Nguen, T., Weiskerger, C., Acrey, B., Zepp, R., Molina, M., Cyterski, M., Whelan, G., Pachepsky, Y.A., Phanikumar, M. 2020. Modeling the photoinactivation and transport of somatic and F-specific coliphages at a great lakes beach . Water Research. https://doi.org/10.1002/jeq2.20153.
DOI: https://doi.org/10.1002/jeq2.20153

Interpretive Summary: Search continues for microbial indicator organisms that could be routinely used to assess risks of water contamination with pathogenic microorganisms harmful for human health. Illnesses resulting from exposure to contaminated water are primarily caused by viral pathogens in both recreational and in other water uses. Viral indicator organisms may be more suitable for beach management. Coliphages constitute the group of viruses that are candidates for being the indicators. However, it needs to be proven that the current knowledge base about coliphage environmental fate and transport is sufficient to interpret and predict their behavior in natural waters. We developed the first fate and transport model for coliphages in beach environment and tested it with monitoring data from a beach site in southern Lake Michigan. Coliphage concentrations were well predicted by the mechanistic models. Results of this work will further stimulate developments of new microbial water quality indicators and related policies and guidance to improve public health protection.

Technical Abstract: Freshwater beaches in the Great Lakes region provide recreational opportunities for millions of residents and visitors and hold considerable economic value. Microbiological water quality at these beaches can be impacted by a variety of sources and activities including storm water runoff, loading from tributaries, agricultural activities and urban sources such as publicly operated treatment works. Fecal indicator organisms (FIOs) such as E. coli and enterococci are often used as surrogates of contamination and to aid management (e.g., open/close beaches, issue advisories). The weak association between traditional FIOs and pathogens is well-known and bacteriophages may have advantages here due to their similarity to viral pathogens in terms of size and persistence in the environment. Although mechanistic modeling of FIOs received attention in the past, efforts to model viruses and bacteriophages in the environment are relatively limited. In this paper, we describe the development and application of a fate and transport model of somatic and F-specific bacteriophages for Washington Park beach in Lake Michigan. A three-dimensional model of lake circulation and phage transport is first tested using current data obtained during the summer of 2014. The light-based inactivation of the phages was modeled based on organism-specific action spectra and results are presented for observed and simulated phage and E. coli concentrations over the summer of 2015. Results indicate that the mechanistic model is able to describe observed concentrations of phages and E. coli well and that the model can be used to test hypotheses about potential sources and their behavior.