Between 2009 and 2022, 15 sediment cores were collected from riverbanks, dam reservoirs or secondary river channels along the Loire River and at the most downstream station of its main tributaries before the confluence with the Loire River (Allier, Indre, Cher, Mayenne, Sarthe, Loir rivers). Each site was selected to integrate the contribution of a maximum of potential pollution sources from upstream while avoiding locations immediately downstream of punctual sources with specific geochemical signals that would mask upstream inputs (e.g. wastewater treatment plants, mining or industrial sites…). The chosen site ensured minimal disturbance and alteration of sediment deposition over the past decades, allowing for continuous sediment accumulation. The core metadata has been registered in the CNRS French Core Repository (https://www.cybercarotheque.fr). Analyses focused on major and trace elements compositions (heavy metals and metalloids), all conducted using the same analytical procedures at the French National Centre for Scientific Research (CNRS) SARM-CRPG facilities (Nancy, France; https://sarm.cnrs.fr). In addition, total and organic carbon, grain-size and 137Cs measurements were carried out at the GéHCO research unit (University of Tours) and at the LSCSE research unit (CEA-CNRS-UNSQ) respectively.

Values with #0.00 are below detection limit, empty values are not measured