Contribution to the assessment of TCE contamination in coastal ecosystems of the Provence-Alpes-Côte d'Azur region

Technology Critical Elements (TCE) is an emerging family of contaminants including: Rare Earth Elements (REE), Platinum Group Elements (PGE), and "non-traditional" metals and metalloids. These elements have unique physico chemical properties (ductility, conductivity, fluorescence) (Dang et al, 2021). They are increasingly used in advanced technologies fields such as electronics, pharmaceuticals, and renewable energies. Despite their growing use, limited data exist regarding their impact on marine ecosystems, particularly in urban and industrial areas. This knowledge gap comes from the complexity of their analysis and their low concentrations in natural environments. Advances in chemical analysis enable to meet this challenge. Recent studies have shown that the biogeochemical cycles of TCEs can be disrupted by their increasing introduction into the environment (Abdou et al, 2019 ; Knappe et al, 2005). The objective of this project is to provide an assessment of TCE contamination in coastal environments. The study area corresponds to the coastline of the Provence-Alpes-Côte d'Azur (PACA, France) region. Results comes from an analysis of surface sediment samples collected during previous campaigns (SUCHIMED, CARTOCHIM, ROCCHSED). Given the wide variety of elements within the TCE family, this project focused on rare earths and platinum. The samples were analysed using triple Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-QQQ-MS) (CCEM, Nantes) to obtain Rare Earth concentrations measurements. Platinum concentrations were determined using Adsorptive cathodic Stripping Voltammetry (AdSV) (MIO, Toulon). Thanks to the archived samples analyzed, this presentation offers an inistial spatial study of the RRE and Pt contamination along the PACA region coastline over the last thirty years. Platinum’s results showed a sharp divergence in concentration depending on the study site. Higher concentrations are revealed in coastal areas near urban areas or rivers rich in anthropogenic inputs. We presume these increases are linked to anthropogenic activity. REE distribution profiles obtained, european shale normalized, are extremely diverse, reflecting the multiplicity of physico-chemical processes taking place in this zone. Each profile thus becomes the digital fingerprint of the site studied, and proves to be fairly stable over time.