According to international commitments for the Oslo and Paris convention (OSPAR) and for the European framework directives (waterframework directive ¿WFD- and marine strategy framework directive ¿MSFD), France implements a water quality monitoring program which results are sent to the international databases. The ROCCH network (French chemical monitoring network) as a part of the French water quality monitoring network, collects the chemical contamination data in the coastal mollusks flesh and in the marine sediment. Sediment monitoring is carried out during annual campaigns in different façade each year, over the duration of a 6 years WFD or MSFD cycle. In 2019, the samples were collected on the french coasts from English Channel (east part) and North Sea, between Dunkerque and Le Mont Saint-Michel.

ROCCH monitoring in sediments enables the assessment of the chemical quality of the near-continental shelf, and its temporal evolution with comparison with the results obtained in previous campaigns. The results of the 2019 campaign will be compared with those of the RNOSED 93, RNOSED 03, ROCCHSED 09 and ROCCHSED13 campaigns in the same area.

Samples are constituted from the 1^st superficial centimeter of the sediment core, for chemical analysis. The list of studied chemical contaminants in a sample depends on the monitoring program (OSPAR or WFD - MSFD) and includes normalizing parameters like grain size or total organic carbon concentration. The complete list includes up to 45 substances or families of substances, with metals, organic components like hydrocarbons, chlorinated, brominated and fluorinated components, pesticides and biocides (TBT).

Data will be stored in the marine environmental database Quadrige and available via SURVAL tool (Ifremer website). Part of the sediment samples will be strored in the ROCCH bank, available for further scientific works. Use of stored samples can be asked to the ROCCH coordination.