A dataset of major and trace element composition in sediments of the Loire river basin (France), records covering 1778-2022.

This paper introduces a comprehensive database documenting major, metallic, metalloid and rare earth elements in sediments throughout the entire Loire Basin, one of the largest basin of western Europe, flowing to Atlantic ocean. This unique compilation integrates three complementary datasets dealing with sediment collected during 2010-2022 and cores represent concentrations ranging from the mid-19th century up to 2022, riverbank profiles and surface sediments collected in the mid 2010s. The sediment core dataset provides a detailed chronological record and includes sedimentological and geochemical analyses from five cores collected along the Loire River, eight cores from its major tributaries, and one from a neighbouring river (Vilaine). In total, 498 dated samples were analysed for 64 parameters offering insights into long-term environmental changes. To enhance the spatial coverage across the basin, the core-based analyses are supplemented by data from 112 sediment samples recovered in riverbank profiles. These samples were strategically collected in sections of the basin where obtaining sediment cores was not unfeasible. Furthermore, the dataset includes analyses of 91 surface sediment samples, which serve to characterize and locate potential present and past anthropogenic sources of trace elements, thereby providing context for sediment records. This rich and multi-faceted dataset offers a robust spatio-temporal record of contaminants driven by anthropogenic impacts. It is a valuable resource for various environmental research applications. Locally, it has already been successfully utilized to investigate the key drivers of contaminant transfer within the Loire Basin. Globally, the scale and comprehensive nature of this dataset make it particularly well-suited for cross-referencing and comparative studies with other European large-river basins. Currently, the spatial and temporal coverage is limited worldwide. However, this work can contribute to a better understanding of human-induced environmental changes across the continent. Finally, particularly within the European Union context, this dataset also serves an operational purpose. It offers in-depth contextualization for contaminant data collected and archived by stakeholders during regulatory surveys.