The TRAJECTOIRE project is a 4-year project launched in January 2020. It aims to establish, at the outlets of the main French river basins (Rhône, Loire, Seine, Garonne, Rhine, Meuse and Moselle), the trajectories of contaminants produced by humans. It involves studying their journey, from their introduction into the environment, until their presence in environmental compartments, throughout the 20th century. This period was punctuated by both technological and industrial development and then by a gradual awareness of the impact of this development on the environment.
The TRAJECTOIRE project will involve the study of three main families of contaminants introduced into the environment by human activities:
- Microplastics and their by-products, such as phthalates,
- And critical metals: ultra-rare metals used in advanced technologies, such as gadolinium, indium, terbium, europium, palladium, platinum and germanium.
The ultimate goal of the TRAJECTOIRE project is to develop a predictive model for concentrations of contaminants in river systems by considering the evolution of anthropogenic pressures on the basis of scenarios. Research work will make it possible to assess the trajectories of the contaminants studied, i.e. the response of environments subjected to anthropogenic disturbances applied to their river basins, as well as the capacity of large rivers to return to their initial state after a disturbance, in other words, their capacity for resilience.
The TRAJECTOIRE project aims to provide stakeholders with a decision-making tool for environmental measures (regulations), for management methods for dismantling and remediation operations and for the materials for use in new technologies, from the point of view of the protection of hydrosystems.
The TRAJECTOIRE project, led by IRSN, is made up of 7 French partners. The ANR is funding this project as part of its 2018 general call for projects on the theme of “Human-Environmental Interactions”.
At the dawn of the 4th industrial revolution, energy transition cannot ignore questions about and awareness of the potential environmental impact of the use of new materials.
If we want to predict the future of the contaminants resulting from these materials, it is a good idea to take an interest in their trajectories within river systems. Rivers are the final repository for many substances and most of them are stored in their sediments, thus constituting “sedimentary archives” which testify retrospectively to the character and contamination levels of these environments.
By studying the trajectories of certain contaminants used by humans during the 20th century, from the point of view of their history of production, management and consumption, it is possible to identify the causal links and to predict future trajectories depending on political, economic or societal choices.
The TRAJECTOIRE project is structured around 5 Work Packages (WP). Two of them (WP1 and 5) are dedicated to coordination of the research project and to the integration, communication and dissemination of results. WP2, 3 and 4 are respectively dedicated to:
- Analysis of sedimentary archives in order to reconstruct time series for contamination levels (WP2)
- Construction of socio-historical narratives charting anthropogenic pressures (WP3)
- Mathematical analysis of the correlations between the anthropogenic pressures documented by WP3 and the evolution of the contamination levels recorded in WP2, as well as the establishment of a scenario-based predictive model for the trajectories of the contaminants
WP2: Reconstruction of contamination levels at the outlets of the main French river basins.
Sediment samples will be taken at the outlets of the main French river basins in areas that are already well referenced (Rhône, Loire, Seine and Garonne) or from new sites to be identified (Rhine, Meuse and Moselle). The objective is to consider anthropogenic pressures and their consequences for the concentration of contaminants in sediments on a large spatial scale, in order to avoid single-case studies which generally limit extrapolations. Sampling sites should be identified by a relatively continuous rate of sedimentation covering the last 100 years.
These sediments will be dated in order to reconstruct the historical contamination of the main rivers, following three methods: two conventional dating methods involving identifying the 137Cs peaks that result from the atmospheric fallout from nuclear tests (1963) and those from the fallout from the Chernobyl accident, and by analysis of excess concentrations of 210Pb.
The third method dates the sedimentary archives when the data obtained by the other dating methods are ineffective. It uses modelling from IRSN's CASTEAUR computer code to calculate the evolution, in time and space, of the distribution of radionuclides released by human activities.
Sediment analysis will include identification of the properties of the particles and the transportation phase of the contaminants, in order to assess their impact on the variation in concentrations of contaminants.
Finally, the contaminants will be analysed along the sediment cores. The historical reconstruction of the contaminant concentrations will be established on the basis of the dating of the sediment cores while taking account of variability factors (particulate organic matter content, granulometry). In order to distinguish contaminants of natural origin from those of human origin and in order to estimate the evolution of anthropogenic impact over the years, the concentrations of contaminants will be calculated by referring to reference levels which, for example, in the case of high-tech metals, represent the natural concentration of contaminants present in soils, which will have to be determined as part of the project. In the case of radionuclides, the reference values will be typical concentrations of the soils of the river basins which are known from IRSN reports. Finally, in the case of microplastics, the reference values remain to be specified but could, for example, correspond to quantification limits.
WP3: Socio-historical narratives
The construction of socio-chronological narratives for the contaminants will be based on archival documents that refer to production methods and rates, the use and storage of materials containing these contaminants, as well as their release into the environment.
They will contain qualitative and semi-quantitative data on changes in regulations relating to these contaminants and on environmental actions concerning them (recommendations, standards, ban on the use of substances, etc.) and on changes in the industrial heritage and usage practices of the various regions of the river basins under study.
The TRAJECTOIRE project will, first and foremost, use the best documented families of contaminants and river basins in order to populate the model developed in WP4.
WP4: Mathematical analyses and modelling
WP4 aims to link the quantitative data from the sedimentary archives of WP2 with the qualitative and semi-quantitative data from the socio-historical narratives created by WP3 in order to elicit causal links.
In order to perform this analysis, the TRAJECTOIRE project will use a neural network generated by the SNNS software (University of Stuttgart).
The initial stage of WP4 will be about testing and improving the mathematical modelling, built by neural networks, by applying it to the most complete data collections already available.
The main objective will be to include qualitative data in the neural network in order to improve its relevance. This exercise should highlight the pressures that have the greatest impact on the concentrations of contaminants and establish a primary version of the operating rules (recognition rules), defining the causal links between a disturbance of human origin and the resulting concentration rates of contaminants.
The second stage of WP4 will consist of extending the model to the other river basins and contaminants in the study. Using this additional data will improve the neural network by adding other recognition rules.
The model thus validated can be used on scenarios involving disruptive actions or restorative actions in order to estimate the impact of these actions on the concentration of contaminants in the sedimentary deposits and the amount of time required before this impact is noticeable.
The TRAJECTOIRE project thus aims to study how human activities can influence the resilience (or lack thereof) of river basins.