Genetic Microbial Source Tracking Support QMRA Modeling for a Riverine Wetland Drinking Water Resource

Julia Derx; Katalin Demeter; Rita Linke; Sílvia Cervero-Aragó; Gerhard Lindner; Gabrielle Stalder; Jack Schijven; Regina Sommer; Julia Walochnik; Alexander K T Kirschner; Jürgen Komma; Alfred P Blaschke; Andreas H Farnleitner

doi:10.3389/fmicb.2021.668778

Genetic Microbial Source Tracking Support QMRA Modeling for a Riverine Wetland Drinking Water Resource

Front Microbiol. 2021 Jul 14:12:668778. doi: 10.3389/fmicb.2021.668778. eCollection 2021.

Authors

Affiliations

¹ Institute of Hydraulic Engineering and Water Resources Management, TU Wien, Vienna, Austria..
² Research Group Environmental Microbiology and Molecular Diagnostics E166/5/3, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria.
³ Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria.
⁴ Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria.
⁵ Department of Statistics, Informatics and Modelling, National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands.
⁶ Faculty of Geosciences, Department of Earth Sciences, Utrecht University, Utrecht, Netherlands.
⁷ Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Vienna, Austria.
⁸ Division Water Quality and Health, Department of Pharmacology, Physiology, and Microbiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria.

Abstract

Riverine wetlands are important natural habitats and contain valuable drinking water resources. The transport of human- and animal-associated fecal pathogens into the surface water bodies poses potential risks to water safety. The aim of this study was to develop a new integrative modeling approach supported by microbial source tracking (MST) markers for quantifying the transport pathways of two important reference pathogens, Cryptosporidium and Giardia, from external (allochthonous) and internal (autochthonous) fecal sources in riverine wetlands considering safe drinking water production. The probabilistic-deterministic model QMRAcatch (v 1.1 python backwater) was modified and extended to account for short-time variations in flow and microbial transport at hourly time steps. As input to the model, we determined the discharge rates, volumes and inundated areas of the backwater channel based on 2-D hydrodynamic flow simulations. To test if we considered all relevant fecal pollution sources and transport pathways, we validated QMRAcatch using measured concentrations of human, ruminant, pig and bird associated MST markers as well as E. coli in a Danube wetland area from 2010 to 2015. For the model validation, we obtained MST marker decay rates in water from the literature, adjusted them within confidence limits, and simulated the MST marker concentrations in the backwater channel, resulting in mean absolute errors of < 0.7 log₁₀ particles/L (Kruskal-Wallis p > 0.05). In the scenarios, we investigated (i) the impact of river discharges into the backwater channel (allochthonous sources), (ii) the resuspension of pathogens from animal fecal deposits in inundated areas, and (iii) the pathogen release from animal fecal deposits after rainfall (autochthonous sources). Autochthonous and allochthonous human and animal sources resulted in mean loads and concentrations of Cryptosporidium and Giardia (oo)cysts in the backwater channel of 3-13 × 10⁹ particles/hour and 0.4-1.2 particles/L during floods and rainfall events, and in required pathogen treatment reductions to achieve safe drinking water of 5.0-6.2 log₁₀. The integrative modeling approach supports the sustainable and proactive drinking water safety management of alluvial backwater areas.

Keywords: Cryptosporidium; Giardia; QMRA; genetic microbial source tracking markers; hydrodynamic model; microbial decay in environment; microbial fate and transport model.