HAL Id: hal-02409637
https://hal.archives-ouvertes.fr/hal-02409637
Submitted on 9 Jun 2020
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Microbiological quality of bathing waters versus sanitary regulation and beach users practices. A case study in
Marseilles
Marie-George Tournoud, Samuel Robert, Mylène Toubiana, Marie-Laure Trémélo, Patrick Monfort, Christian Salles
To cite this version:
Marie-George Tournoud, Samuel Robert, Mylène Toubiana, Marie-Laure Trémélo, Patrick Monfort, et al.. Microbiological quality of bathing waters versus sanitary regulation and beach users practices. A case study in Marseilles. Séminaire annuel du Labex DRIIHM, Oct 2019, Lyon, France. 2019. �hal-02409637�
Microbiological quality of bathing waters versus sanitary regulation and beach users practices.
A case study in Marseilles
TOURNOUD Marie-George
1*, ROBERT Samuel
2, TOUBIANA Mylène
1, SALLES Christian
1, APERS-TREMELO Marie-Laure
2, MONFORT Patrick
11
HSM, Univ Montpellier, CNRS, IRD, Montpellier, France.
2
ESPACE, Aix Marseille Université, Université Côte d'Azur, Avignon Université, UMR 7300, Avignon, France.
• Urban beaches are social and ecological coastal interfaces facing up human and environmental challenges, such as allowing bathing activities free from sanitary
issues.
• In France, according to the EC Bathing Water Directive (2006/7/EC), the quality of bathing waters is monitored by the Regional Health Agencies (ARS). Water is sampled once a week during the bathing season, the result is available 24 hours later. In case of insufficient quality, local authorities are in charge of deciding to prohibit bathing.
• In Marseilles, a municipal monitoring of the bathing waters is organized on a daily base, with a sample made at 5 AM. Though a non-standardized method is used to assess the microbiological quality, the result is available in 2 hours, making thus possible to take a faster decision.
• does the sampling strategy lead to a sound assessment of the quality of bathing water on a day-to-day basis ?
• is the microbiological quality of bathing waters linked to the number and the behavior of beach users ?
• what are the users' expectations and their practices regarding the quality of bathing waters ?
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Dynamics of fecal contamination
indicators in bathing waters
versus bathing authorization
Quality of bathing waters
versus number of users
Beach water quality
versus users expectations and practices
à compléter
Prophète beach
There is no obvious
link between fecal
contamination and number of users,
high bacteria levels
are observed on the
early hours of the day
but, for some days,
the peak of attendance matches with high
bacterial levels. 0 50 100 150 200 250 300 350 0 200 400 600 800 1000 1200 1400 8 10 12 14 16 18 20 u fc / 1 0 0 m L N u m b e r o f u se rs July, 12 2017 CTT EI USERS 0 50 100 150 200 250 300 350 0 200 400 600 800 1000 1200 1400 8 10 12 14 16 18 20 u fc / 1 0 0 m L N u m b e r o f u se rs July, 13 2017 CTT EI USERS 0 50 100 150 200 250 300 350 0 200 400 600 800 1000 1200 1400 8 10 12 14 16 18 20 u fc / 1 0 0 m L N u m b e r o f u se rs July, 16 2017 CTT EI USERS 0,1 1 10 100 1000 July,13 2017 C o lif o rm e s T h e rm o to le ra n ts (u fc /1 0 0 m L ) 0,1 1 10 100 1000 July,13 2017 E n té ro c o q u e s (u fc / 1 0 0 m L ) 0,1 1 10 100 1000 July,11 2017 C o lif o rm e s T h e rm o to le ra n ts (U F C / 1 0 0 m L )
Beach users are very much concerned about water quality. But the majority of them do not pay attention to the official measurements of the bathing water quality. Nearly half of them do not use the toilets.
0% 20% 40% 60% 80% 100% Pas important du tout Plutôt pas important Plutôt important Très important NSP NA
Is water quality an important topic at the beach ? 0% 20% 40% 60% 80% 100%
Oui Non Je ne sais pas NA
Do you know if the bathing water quality is monitored at the beach ?
0% 20% 40% 60% 80% 100% Oui Non
Did you see the table providing the data ? 0% 20% 40% 60% 80% 100% Oui Non NA
Do you usually use the toilets at the beach ?
0% 20% 40% 60% 80% 100%
Jamais Peu Fréquemment A chaque fois NA
Usually, do you bath at the beach ?
Bathing is highly
practiced at the beach.
The hourly fluctuations of fecal contamination of bathing waters makes ineffective the unique dawn control made by Marseilles. It is necessary to adapt the strategy according to the variability or to the not-yet identified causes of variability.
0.1 1 10 100 1000 July,11 2017 E n té ro c o q u e s (U F C / 1 0 0 m L )
Pointe Rouge beach
Bathing is prohibited despite of a GOOD bacteriological quality Lave beach Bathing is allowed despite of a BAD bacteriological quality
Despite of significant efforts to manage wastewater and treated effluents, the urban beaches of a large city such as Marseilles are subject to diffuse contaminations requiring a more suitable sanitary control of bathing waters.
The results of the survey of bathers on the use of toilets allow us to say that users themselves could contribute to these contaminations.
Lave beach 3 days (2017) 39 samples - 39 pictures 86 questionnaries Prophète beach 3 days (2016) + 7 days (2017) + 1 day (2018) 143 samples -143 pictures 362 questionnaries
Pointe Rouge beach
3 days (2017)
39 samples - 39 pictures 76 questionnaries
Bathing water quality
hourly water sampling
+ fecal indicators quantification
Users' practices
questionnaries + statistical analysis
Beach attendance
counting beach users + incoming-outgoing users
20m
2 3 4 5 6 7 8 9 10
sampling point
Three urban beaches in Marseilles
In-situ co-observations + three
co-designed field protocols
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Prophète beachLave Pointe Rouge Prophète
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From 8:00 am to 8:00 pm