Distribution and dispersal of suspended particulate matter on the Ebro continental shelf, northwestern Mediterranean Sea

Hydrographic data, water and bottom-sediment samples, and a GEOPROBE tripod experiment were used to examine the distribution and dynamics of suspended particulate matter on the Ebro shelf in the northwestern Mediterranean Sea. In the absence of strong winds and storms, primary sediment supply from the Ebro River is dispersed along the shelf by a general southward flow. In such calm conditions, suspended-matter concentrations on the shelf are lower than 3 mg/l and transfer of material from the shelf to the slope takes place principally over the shelf edge north of the Columbretes Islands. Very fine sediment deposited in a mid-shelf mud belt (30-80 m deep) is cohesive and resistant to erosion. Only relatively rare, strong storms are able to resuspend particles from the deeper, central region of this cohesive deposit. When resuspension takes place, suspended-particulate-matter concentration increases and the general dispersal pattern of suspended matter is altered. Near the seafloor, distribution of suspended matter is greatly influenced by the distribution of the mid-shelf muds from which particles are resuspended. Resuspension occurs more intensively and frequently along the shallower (20-40 m) edge of the cohesive deposit and near the delta. ?? 1990.