CIRCOLAZIONE DELL AZOTO IN VAL MASINO: STUDI CONDOTTI IN AMBIENTI DI ALTA QUOTA

Nitrogen dynamics in running waters and snowpack samples were investigated in the high-elevation part of the Val Masino catchment, in the Italian Alps. his area was studied and monitored since 1994 within the CON.ECO.FOR. project. Studies of the soil solution showed a complete assimilation of nitrogen in forested areas, but the atmospheric deposition trends and the evolution of nitrate in the Masino stream suggested an intermediate condition of N saturation. In 2007 the DIVALPA project started, aiming to identify the nitrate sources and the most important biogeochemical processes responsible for nitrogen loads in the stream at 1190 m asl. Median measured N-NO3 - concentrations were 16 ?eq/l in running waters, 4 ?eq/l in snow and 24 ?eq/l in rain. A PCA analysis was performed on the chemical species concentration of the running water sites and three principal axes, explaining 73 % of the total variation, were identiied.