Recent deposits and suspended sediments off the Po della Pila (Po River, main mouth), Italy

Present sedimentary conditions in the prodeltaic marine area immediately in front of the Po della Pila (Po River main mouth) are characterized by a maximum thickness of Holocene muds of 10-12 m at a depth of 20-25 m and by two different sedimentary cycles, with the more recent lens-shaped unit (2.5-4.0 m thick) probably deposited in the last 300 yrs. The nearshore prodelta area is characterized by rapidly accumulating deposits (2-4 cm/yr) enriched in smectite, gas, organic material (1 2~o) and trace metals. The water system presented well marked vertical stratification during the summer of 1985, revealing three distinct water bodies: (1) riverine and diluted waters (average depth of 3 m), (2) middle depth waters (10-20 m) and (3) bottom waters. Temperature, oxygen and particulate organic carbon decrease with depth whilst total suspended matter, yellow substances and total particulate carbon show maxima at the surface and in the bottom layers, and minima in the intermediate waters, where the organic fraction comprises 42% of the total.