The sedimentary infill of the Pertusillo freshwater reservoir (Val d'Agri, Southern Italy)

Freshwater reservoirs fed by multiple tributaries supplying water and sediments from different catchment areas are poorly known, notwithstanding their worldwide diffusion and environmental value. The purpose of this study, focused on the sedimentary Mill of the Pertusillo freshwater reservoir in Southern Italy, was to illustrate the complex sedimentary pattern that can develop in these water bodies, characterized by multiple point sources of sediments, complex hydrodynamics and dramatic water-level fluctuations. The environmental studies of such reservoirs must necessarily take into account the complexity of the sedimentary processes and the variability of bottom sediments where pollutant accumulate, in order to understand the complex geochemical pattern of these basins, that play an important role for the human life. 15 sediment cores, up to ~2 m long, were collected to study the sedimentable and lithostratigraphic characteristics of the sedimentary infill of the Pertusillo reservoir, in Val d'Agri (Southern Italy). 11 lithofacies were identified, whose areal variability is the result of the complex sedimentary processes in the reservoir, related to its complex morphology and hydrology with dramatic seasonal fluctuations of the water level, and to the presence of multiple tributaries. Two mam different depositional areas separated by a transition zone were identified in the reservoir: a proximal coarser-grained deltaic area, characterized by high hydrodynamics and sediment variability, with multiple longitudinal and lateral deltas, and a distal quiet and muddy "lacustrine" area, where black anoxic beds also occur. The latter are common in eutrophicated waters, due to the abundance of nitrogen and phosphorous produced mainly by agricultural and industrial activities, both present in the study area, where the large Val d'Agri oil field occurs. © by PSP