[1] Biogeochemical cycling of N and S was examined at two watersheds in the Adirondack Mountains, New York, to better understand the retention and loss of these elements during winter and spring snowmelt. We analyzed stable isotope compositions of NO3 (dN-NO3 , dO-NO3 ) and SO4 2 (dS-SO4 2 , dO-SO4 2 ), along with concentrations and fluxes of NO3 and SO4 2 , in precipitation, throughfall, snowp...