C, N AND THEIR STABLE ISOTOPES IN SUSPENDED AND SEDIMENTED MATTER FROM THE PO ESTUARY (ITALY)

C and N content, C/N (atomic) ratio, and C and N isotopic composition (delta(13)C and delta(15)N) were determined on suspended particulate m atter and sediment samples obtained from riverine, estuarine and marin e environments in two cruises (September 1995 and March 1996) in the P o estuary (Italy). Isotopic tracers of C and N, reported for the first time for this environment, gave information on sources of organic mat ter and their distributions. An end-member mixing model based on delta (13)C values was applied to estimate the relative importance of riveri ne and marine sources of organic matter in suspended particulate matte r and sediments.