Isotopic assessment of NO3 and SO4 2 mobility during winter in two adjacent watersheds in the Adirondack Mountains, New York

[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, snowpack, snowmelt, soil water, groundwater, and stream water. Isotopic results showed no evidence of NO3 and SO4 2 transformations in the forest canopy and snowpack; however, markedly decreased dO values of NO3 and SO4 2 in forest floor water suggest that microbial processing occurred in organic soil horizons. Similarly low dO values of NO3 and SO4 2