This document summarizes a study examining virus concentrations in Lake Geneva, which is used as a drinking water source. The researchers used 3D water quality modeling combined with measurements of virus concentrations in sewage to simulate virus transport and decay in the lake. They found that norovirus posed the greatest infection risk, while enterovirus posed the least. The results showed that virus concentrations at specific sites depended on factors like distance from contamination sources, season, wind conditions, and virus decay rates. Stochastic simulations helped account for uncertainties, and the researchers suggested further refinements to consolidate the model.

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Chaojie Li1, Émile Sylvestre2, Xavier Fernandez Cassi3,Tim Julian2, Tamar Kohn1
1Laboratory of Environmental Chemistry(LCE), EPFL, Lausanne 1015, Switzerland 2Department Environmental Microbiology, Eawag, Überlandstrasse 133, 8600, Dübendorf, Switzerland
3Faculty of Pharmacy and Food Sciences, UB, Av. de Joan XXIII, 27-31, 08028, Barcelona, Spain

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Study site: Lake Geneva
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Located on the border of
Switzerland and France.
Used as a drinking water
source and recreational
water site by more than
800,000 inhabitants. It
has a surface area of 580
km2 and a maximum
depth of 310 m.

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A schematic view
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Methods overview
3D Water quality modeling
Sewage virus measurement
and characterization
Environmental virus decay
Simulated virus concentration

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Methods overview
3D Water quality modeling
QMRA
Sewage virus measurement
and characterization
Environmental virus decay
Simulated virus concentration

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Hydrodynamic and water quality module
Source: http://meteolakes.ch/
Hydrodynamics: Delft3D 4 Based online platform: Δt =1 min, Δx ≈400 m, 100 Z-layers.
Water quality: Delft3D-WAQ, validated with surrogate of total suspended matter. Spatial and temporal
inactivation of virus included.

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Environmental inactivation of waterborne virus
𝑙𝑜𝑔10𝑘 = 𝛽0 + ෍
𝑖=1
𝑛
𝛽𝑖𝑥𝑖 + 𝜀
Boehm, A. B., Silverman, A. I., Schriewer, A., & Goodwin, K. (2019). Systematic review and meta analysis of decay rates of waterborne mammalian viruses and coliphages
in surface waters. Water Research, 164, 114898.
Virus type Beta 0 Beta temp Beta solar (surface)
Rotavirus -0.6 0.04 0.51
Norovirus -1.08 0.04 0.43
Adenovirus -1.2 0.07 0.13
Enterovirus -0.25 0.03 1.07
The first-order inactivation rate, k

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𝐸𝑥𝑝𝑜𝑛𝑒𝑛𝑡𝑖𝑎𝑙:
𝑃 = 1 − 𝑒(−𝑟∗𝑑𝑜𝑠𝑒)
𝐵𝑒𝑡𝑎 − 𝑃𝑜𝑖𝑠𝑠𝑜𝑛:
𝑃 = 1 − (1 + 𝐷𝑜𝑠𝑒/𝛽)−𝛼
Dose-response models for
different viruses:
Source: http://qmrawiki.org/
𝐵𝑒𝑡𝑎 − 𝐵𝑖𝑛𝑜𝑚𝑖𝑎𝑙:
𝑃 = 1 −
𝛤(𝛼+𝛽)𝛤(𝛽+𝑑)
𝛤(𝛽)𝛤(𝛼+𝛽+𝑑)
Enterovirus
Adenovirus
Rotavirus
Norovirus

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Case studies: Site and scenarios
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Release sources:
Vidy WWTP and
Morges WWTP.
Site of interest:
Morges recreational
site.
Weekly simulation: 3 days of continuous release of raw sewage + 4 dry days. 24 cases in year 2019.

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Measurement of virus concentration in raw sewage
PCR measurements
DNA and RNA Samples from sewage
Rotavirus has higher annual mean concentration then the rest, also shows possible seasonality.

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Characterizing virus concentrations in sewage
PLN performs slightly better than the
PGA distribution.
Poisson lognormal
Poisson gamma
Parameter Virus Adenovirus Enterovirus Norovirus Rotavirus (Summer/Winter)
Mean of samples
(GC/ml)
561 482 10488 1041/18446
DICm PLN 179 176 253 114/143
DICm PGA 181 183 247 113/178
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Concentration evolvement over one week
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Nearshore virus concentration and infection risks
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Two sources:
Vidy WWTP and
Morges WWTP.
One source:
Vidy WWTP.

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The influence of environmental stressors
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The influence of environmental stressors
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Stochastic simulations for risk characterization
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The incoming sewage virus
concentration was considered a
stochastic process. The uncertainties
related to the water intake volume
and the dose-response relationships
were not included in this study.

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Annual risk characterization
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Eastward wind
Westward wind
Source: NEMS meteroblue
Annual mean Westward wind Eastward wind Eastward/Westward
Adenovirus 0.078 0.089 0.045 51%
Enterovirus 0.0003 0.0003 0.0001 33%
Norovirus 0.685 0.713 0.603 85%
Rotavirus 0.035 0.04 0.021 53%

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Norovirus is the most acute species among the viruses studied according to the
case studies while enterovirus poses the least danger.
Summary and outlook
The relative distance to the contamination sources, the season, wind conditions
as well as inactivation rates are essential in determining virus concentrations at
a specific site in lakes.
Stochastic simulations can indicate uncertainties in risk assessment. More
information on the sewage virus concentration and uncertainties related to the
dose-response of viruses would further consolidate the model.
Online visualization of the results, the implement of flexible mesh and hopefully a
better coupling scheme for the inactivation module.

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Acknowledgements
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Prof. Tamar Kohn
Dr. Tim Julian Dr. Émile Sylvestre Dr. Xavier Fernandez Cassi
&

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Thank you!
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