Landscape controls on stream water nitrate ions in the Archer Creek Catchment of the Adirondack Park, New York

Stream water NO3- concentrations of catchments within the northeast U.S. have shown substantial variation over time and among sites. I evaluated the mechanisms explaining the marked differences in stream water chemistry between two nearly adjacent subcatchments (S14 and S15) in the Archer Creek Catchment in the Adirondack Mountains of New York. Analyses of hydrological events provided further information on hydrological controls on stream water NO3-.; Subcatchment 14 had two-fold greater stream water Ca2+ and NO3- concentrations than S15. These differences in stream water chemistry were attributed to variability in tree species composition and soil properties. Soils in S14 had significantly higher total elemental and exchangeable Ca2+ and extractable NO3 - concentrations. The total basal areas of base-rich indicator tree species including sugar maple were significantly greater in S14 while S15 had significantly more American beech and eastern white pine.; Using combined hydrometric and hydrochemical data I developed a conceptual model of NO3- release in the two subcatchments during late summer/early fall storms 2002 and snowmelt 2003. The relative contributions of water sources were similar between the two subcatchments. Temporal pattern of stream chemistry varied due to differences in the concentration of solutes in water sources.; I further characterized the groundwater as well as stream water in the entire Archer Creek Catchment and its subcatchments. The variability in groundwater chemistry between subcatchments was explained by varying attributes of the catchments such as differences in NO3- production in S14 versus all other subcatchments. These synoptic results agree with the more detailed studies of S14 and S15 with respect to temporal patterns of water sources.; This research has provided a better perception of landscape controls on stream water NO3- and other solutes in the Archer Creek Catchment. It has suggested that differences in surface water chemistry need to account for the role of soil properties and tree species composition in affecting biogeochemical relationships. To evaluate overall landscape controls on surface water chemistry it is important to characterize water and solute sources of surface waters and how these source areas vary with space and time.