Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 3 2009 10.5194/hess-13-423-2009 http://www.hydrol-earth-syst-sci.net/13/423/2009/ http://www.hydrol-earth-syst-sci.net/13/423/2009/hess-13-423-2009.html http://www.hydrol-earth-syst-sci.net/13/423/2009/hess-13-423-2009.pdf 423 439 2009-03-25 Spatial and temporal dynamics of stream chemistry in a forested watershed K. B. Piatek kathryn.piatek@mail.wvu.edu S. F. Christopher M. J. Mitchell West Virginia University, Division of Forestry and Natural Resources, P.O. Box 6125, Morgantown, WV 26506, USA State University of New York College at Buffalo, The Great Lakes Center, Buffalo, NY 14222, USA State University of New York, College of Environmental Sciences and Forestry, 1 Forestry Drive, Syracuse, NY 13210, USA Spatial dynamics of solute chemistry and natural abundance isotopes of nitrate (¹⁵N and ¹⁸O) were examined in seven locations and at the watershed outlet in 2001 and 2002 in a forest watershed in the Adirondack Mountains of New York State, USA. Temporal dynamics were examined during five discharge periods: winter, snowmelt, spring, summer, and fall, based on discharge levels at the watershed outlet. Solute concentrations were variable across space and time with significant (<i>p</i>&le;0.05) interaction effects. Year*period was significant for pH, NH₄⁺, NO₃^-, total N, DOC, and total Al suggesting that inter-annual variability in discharge levels was more important for these solutes than intra-annual variability. Period*sampling point was significant for pH, Mg²⁺, Ca²⁺, sum of base cations, Si, and total Al suggesting that the differences in concentration of these solutes among sampling points were moderated by discharge levels. In general, groundwater sources located in upper watershed controlled stream chemistry at higher elevations with highest pH, Ca²⁺, sum of base cations, Si, and SO₄^2- concentrations, with higher values in summer, and dilution effects during snowmelt. Two low elevation wetlands had a substantial influence over stream chemistry at those locations contributing lowest NO₃^- and highest DOC. Snowmelt exhibited among the lowest pH, sum of base cations, and SO₄^2-, and highest NO₃^-, total N, and total Al; snowmelt appeared to dilute groundwater, and flush stored soil-derived solutes. Summer discharge, composed mainly of groundwater, exhibited the lowest flow, among the highest Mg²⁺, Ca²⁺, and lowest DON, DOC, and total Al concentrations. 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