Sedimentable mineral organic detritus as radioecological indicator

The sedimentable mineral organic detritus (SMOD) drawn by rivers can be considered an important matrix for the monitoring of contaminants in aquatic environments. In Italy the collection and radioactivity analysis of SMOD has been introduced and standardised in the 80s. However hydrological parameters, like the flow and the amount of suspended matter close to the sampling points, must be considered to improve the methodology. This technique has been applied by the authors since 1992 to monitor the concentration of both 137Cs (following the Chernobyl accident) and 131I (because of possible waste discharge from Perugia University Hospital) along the Umbrian course of the Tiber River. In this paper the results of 137Cs water concentration are presented and discussed in the light of our interpretative working hypothesis based on hydrological parameters. This work allowed us to reduce the number of sampling points without loss of radioecological information.