SULFUR AND NITROGEN BUDGETS FOR 5 FORESTED APPALACHIAN PLATEAU BASINS

Sulfur and nitrogen input-output budgets were estimated for five fores ted Appalachian Plateau basins in Pennsylvania for the period October 1988 to March 1990. Wet and dry deposition inputs were determined on a weekly basis from data collected at atmospheric deposition monitoring stations located near the study sites. Stream export was estimated fr om intensively sampled stream chemistry and continuous discharge data collected on all five basins. On four of the five basins, deposited su lfur was essentially in balance with stream flow export of sulfur (92- 120% exported) for the 1989 water year. The fifth basin had net retent ion of deposited sulfur, with only 42% exported. All five basins retai ned the vast majority of deposited nitrogen(only 3-18% exported). The fraction of atmospherically deposited sulfur exported in stream flow w as greater by a mean factor of 14 versus nitrogen, implying that sulfu r dominates base cation leaching processes on these non-carbonate-base d catchments; Although basins in the study were relatively homogeneous in terms of topography, climate, geology and land use, local basin co nditions caused significant differences in input-output budgets, point ing to the need for replicated basin studies in a region. (C) 1997 by John Wiley & Sons, Ltd.