ELEMENT FLUXES AND LINKAGE BETWEEN TERRESTRIAL AND AQUATIC ENVIRONMENTS IN FRESH WATER ALPINE STREAMS

Concentration and quality of carbon (C) and nitrogen (N) in alpine stream water was studied along two vegetation gradients in the Abisko region to assess how changes in vegetation cover, due to climate changes, will affect the studied elements. Stream water samples were collected and analyzed for dissolved organic carbon (DOC), total nitrogen (Tot-N), ammonium (NH4 + ), nitrate (NO3 - ) and spectrophotometric data. We found that DOC and dissolved organic nitrogen (DON) concentrations increased in the stream water with increasing vegetation (R² = 0.64 and R² = 0.44 respectively) and NO3 - concentrations decreased with increased vegetation (R2 = 0.71). The quality indicators SUVA, aromaticity and DOC:DON ratio all showed negative relationships with average catchment altitude (R2 = 55, R2 = 59 and R2 = 46 respectively). These indicators show trends of less bioavailable C reaching the lakes. Our findings suggest that vegetation has an impact on DOC cycling and to a less degree also affecting DON cycling, which will most likely induce responses in aquatic systems.