ROCCH, the French Chemical Contaminant Monitoring Network, regularly provides a new dataset for assessing the chemical quality status of French coastal waters. Concentrations of trace metal elements and organic compounds are measured in samples of marine surface sediments collected in the English Channel, Bay of Biscay and mediterranean lagoons, during 4 campaigns over a period of 6 years. Samples of fine sediment material, from 200 to 250 monitoring stations, are freeze-dried and sieved prior to analysis. The results are submitted to the international databases of Regional Sea Convention (OSPAR Convention for North East Atlantic and Barcelona Convention for Mediterranean) and diffused to public Stakeholders.

The ROCCHSED campaign (sediment component of the ROCCH programme), which took place in spring 2023, analysed around 140 historical chemical substances (metals, PAHs, etc.) and emerging substances (PBDEs, PFAS, etc.), measured nitrogen and phosphorus concentrations and counted microplastic particles in surface sediments sampled at around sixty points in twenty one lagoons in Occitanie, Bouches du Rhône and Corsica (France). Results were compared to references to evaluate chemical quality of the lagoon ecosystems.