Release of nutrients into a forested catchment of southern Italy

This work aims to improve the knowledge of nutrient exchanges between soil and atmosphere through a comparative analysis of the contribution coming from atmospheric depositions and their release in water runoff. The study has been realized on a mountain catchment, crossed by Bonis stream, tributary of Cino river and located in Sila Greca plateau (Calabria, Southern Italy). This experimental basin, laying on a basement formed by inclusive and plutonic rocks, extends for an area of 139 hectares, spreading from 975 to 1301 m a.s.l. The catchment is forested for about 95 % of its surface area with the main presence of Pinus laricio Poiret populations differentiated for age, density, tree canopy cover and stand characteristics within an area without human settlements and pollution sources. The basin has been instrumented, since 1986, to measure the main abiotic features in inflow and outflow discharges. These chemical and physical parameters, as N-NH4, N-NO2, N-NO3, P-PO4, S-SO4, Cl, pH and conductivity, have been analyzed on a fortnightly basis. From collected data, it has been estimated, for each nutrient, its annual and monthly mean weighed concentrations to value the basin resilience after external inputs and its rolling action after some events, as acid depositions. In conclusion, the monitoring of mountain catchments could supply useful data about the global changes of atmospheric chemistry and, as a consequence, on the variability in quality control of surface waters, considering that mountain catchments supply most of water resources of a good-quality level for mankind.