Cartographie et caractéristiques des sédiments superficiels du secteur conchylicole de l'étang de Thau

Sediments from the shell-fish culture areas in the Lagoon of Thau are mainly constituted of sand and mud elements ; at a depth of about 80 cm to 1 meter in the sediment, much coarser elements are found. These sediments are more clayey in the N-E corners of each area and in a general way, richer in organic matter than the other areas of the lagoon, with very negative oxido-reduction potentials. Ammonia and phosphate amounts in intersticial waters are very high. A gradient of concentration from the bottom towards the surface of the sediment is observed, thus inducing diffusing flows in the water column.