CE34 - Contaminants, écosystèmes et santé

Integrated biogeochemical, geographical and hydrological approaches to track sources of contaminants in mixed land-use watersheds – CHYPSTER

Identification of contaminant sources in watersheds for water quality prediction

The sources of contaminants impacting rivers are numerous and sometimes difficult to identify. The CHYPSTER project proposes to develop integrated tools to identify the sources (diffuse/point sources) of anthropogenic contaminants and to predict the contamination of rivers as a function of hydrological conditions, land-use changes and climate change.

Improvement of tools to characterize sources (diffuse/point sources) of contaminants

The presence of numerous chemical and microbiological contaminants in aquatic ecosystems can lead to significant degradation of the ecological status of natural waters and increase human and animal exposures to these contaminants through drinking water, crop irrigation, or recreational uses; they may also trigger a rise of antimicrobial resistance genes and bacterial pathogens in hydrosystems. Mesoscale watersheds (~10-103 km²) are particularly sensitive to such contaminations. Increasing surface artificialization as well as climate change could aggravate these impacts and results in critical degradation of water quality in these watersheds. The sources of contaminants impacting the rivers are numerous. While point sources are relatively easy to identify, it is more difficult to identify all non-point sources of contaminants, especially in mixed land-use mesoscale watersheds.<br />The CHYPSTER project aims to define and test a new integrated methodology to identify sources of anthropogenic contaminants and to predict the contamination of rivers as a function of hydrological conditions, land use changes and climate change. This approach is applied to two mesoscale watersheds (the Claduègne in Ardèche; and the Ratier, a sub-basin of the Yzeron, near Lyon), by combining a diagnosis of land-uses and practices, the analysis and monitoring of biogeochemical fingerprints, and distributed hydrological modeling. A better knowledge of the nature of the main chemical contaminants encountered in the watersheds, as well as their sources and the role of these different factors in their fate, will allow a better understanding of their large-scale dissemination and, in the long term, contribute to limiting the emission of these contaminants in the natural environment and/or to proposing adapted mitigation strategies.

The first step is to identify and locate potential sources of contaminants at the watershed scale, in order to define water sampling sites for chemical and microbiological analyses. In this aim, surveys are conducted with stakeholders in the territory in order to identify practices and management methods at the watershed scale. At the same time, maps of land use and cover are produced from remote sensing data and various databases in order to finely represent the activities and uses in the two watersheds studied: the Claduègne watershed and the Ratier watershed (sub-basin of the Yzeron).
The CHYPSTER project is then based on the acquisition of a large set of data from analyses (chemical and microbiological) of water samples collected on these two watersheds with, on the one hand, field campaigns of the sources (identified during the previous step) and, on the other hand, the monitoring of hydrological events at the watersheds' outlets. The sources of contaminants are characterized in order to define specific biogeochemical fingerprints, which will then be combined with the fluxes simulated at the watershed outlets by a distributed hydrological model. The model validated on hydrological events monitoring will be applied to targeted scenarios to estimate the contribution of sources and predict contaminant cocktails in the river, according to different watershed trajectories evaluated with local socio-economic stakeholders.

The sampling methodology for sources (diffuse/point sources) related to land use and land cover is finalized and applied in the project. About 10 «source« sites targeted for sampling have been identified and located in each of the two watersheds studied. Several sampling campaigns have been carried out and have resulted in the collection of more than 170 samples (out of 180 planned). The results of the chemical and microbiological analyses carried out on the samples collected are stored in a database. These data are already being used to refine the methodology for the construction of biogeochemical footprints of the Yzeron and Claduègne sources. In addition, a first mapping to identify contaminant sources using low-cost tools (spectrophotometric and microbiological analyses) has been carried out on the Ratier basin (Yzeron). Samples were collected for UV-Vis and qPCR analyses at more than 50 sites over one day.
In order to be able to use the J2000P distributed hydrological model to decompose river flows and plot the contributions of different sources, a spatial flow decomposition module was developed and applied to the Ratier watershed. Integrated to the J2000P model, this module allows to track the contributions to the total flow of the different sources of contamination identified on the basins of the project, at each time step and at any point of the hydrographic network (including the outlets). This spatial flow decomposition module is currently integrated into the J2000P model of the Ratier watershed. It will also be integrated in the Claduègne watershed in the future. The next step will be to compare the hydrological modeling at the watersheds outlets with the decompositions of the biogeochemical mixing models for the targeted hydrological events.

This project will provide new knowledge on the characterization of chemical cocktails and microbial contamination of freshwater ecosystems. The results will facilitate the location, identification and quantification of the main sources of contaminants related to mixed land-use (multiple sources) and mesoscale watersheds, in order to define and initiate relevant actions (e.g., management of storm water outfalls and retention basins for the urban part, buffer zones in agricultural areas) to reduce inputs of contaminants to the hydrosystems and associated ecological risks and impacts. The future projections of river water quality, based on land use and cover change scenarios, will provide keys for water resources and land-use management at the watershed scale to reduce the potential contamination. This project will contribute to the development of innovative tools and markers for water quality monitoring, transferable to other research laboratories, including private ones.

The CHYPSTER project was presented at the OZCAR seminar (March 2022) and the OTHU seminar (June 2022), which allowed to communicate the objectives and the first results of the project to a large scientific audience at the national level. The advances on hydrological and geochemical models have been presented at several national and international conferences (O. Grandjouan thesis).
The article Bouchali et al. (Microorganisms, 2023; doi.org/10.3390/microorganisms11040922) presents an exploratory study of the modalities of correlations analyses between concentrations of pharmaceutical compounds and bacterial taxonomic entities for collected samples within impacted watersheds.
The paper by Boukra et al. (STOTEN, 2023; dx.doi.org/10.1016/j.scitotenv.2023.162104) explores the relationship between land use and cover, and dissolved organic matter fingerprints obtained in river samples downstream of homogeneous sub-watersheds.

The presence of numerous chemical and microbiological contaminants in aquatic ecosystems, including toxic (e.g. endocrine disruptors) and/or persistent contaminants can lead to a significant degradation of the ecological status of natural waters and increase human and animal exposures to these contaminants through drinking water, crop irrigation or recreational uses; they may also trigger a rise of antimicrobial resistance (AMR) genes and bacterial pathogens in hydrosystems. Mesoscale watersheds (~10-1000 km²) with mixed land-use and heterogeneous geologies are particularly sensitive to such contaminations. In the near future, increasing surface artificialization as well as climate change could result in critical degradation of water quality in these watersheds. The identification of contaminant sources in mesoscale watersheds, including non-point sources, the estimation of their contributions to watershed outlets, and the prediction of water quality in a context of climate change and land-use trajectory are key issues for the development of action plans to reduce contamination of freshwater ecosystems and protect their ecological state.
This CHYPSTER project aims to define a new interdisciplinary approach to identify the sources of anthropogenic contaminants and predict future water quality trajectories based on hydrological processes, changes in land-use and anthropogenic activities, and climate change. This approach will be applied on two mesoscale watersheds (the Claduègne and Yzeron sites that belong to the national research infrastructure OZCAR) by combining diagnosis of land cover and uses of chemicals, biogeochemical fingerprinting, and distributed hydrological modelling. Methodological expertise in spatial analysis, combining geomatics and survey, will be mobilized in order to identify potential sources of contaminants and their location. Advanced passive sampling, and target and non-target analytical tools, both chemical and microbiological, will be deployed to obtain specific datasets on contaminant sources and allow building-up new biogeochemical fingerprints that will be combined with flow contributions estimated by the hydrological model for hydrological events. The use of the validated hydrological model on scenarios of climate change and territories trajectories evaluated with local socio-economic actors will allow to make predictions on the surface water chemical and microbiological qualities at the outlet of watersheds.
This project will bring new knowledge on the characterization of chemical cocktails and microbial contamination (AMR and pathogen–related genes, source-specific keystone taxa) of freshwater ecosystems. The results will facilitate the location, identification and quantification of the main sources of contaminants (including Contaminants of Emerging Concerns [CECs]) along with land-use in catchments of mixed land-use (multiple sources) and mesoscale, in order to define and then initiate relevant actions (e.g. management of storm water outfalls and retention basins for the urban part, buffer zones in agricultural areas) to reduce contaminant pressure onto hydrosystems and the related hazards and ecological impacts. The projections of future river hydrology and water quality according to land-use and land cover change scenarios will also give keys for water and soils management at the catchment scale, in order to reduce contaminations. This project will also contribute to the development of innovative tools and markers for the monitoring of water quality that will be transferable to other research laboratories including private ones. Interestingly, the use of passive samplers termed germcatchers will allow to infer the relationships between chemical pollutants and bacterial taxa developing as biofilms in river systems. These data will thus bring novel insights on resistomes emerging in the environment, and the associated AMR gene recruitments or bacterial taxa enrichments.

Project coordination

Marina Coquery (Fonctionnement des hydrosystèmes)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

PACTE Pacte - Laboratoire de sciences sociales
RiverLy Fonctionnement des hydrosystèmes
LEM Ecologie microbienne
IRD-IGE Institut des Géosciences de l'Environnement

Help of the ANR 610,453 euros
Beginning and duration of the scientific project: September 2021 - 48 Months

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