CLIMATIC CONTROL OF NITRATE LOSS FROM FORESTED WATERSHEDS IN THE NORTHEAST UNITED-STATES

Increased losses of nitrate from watersheds may accelerate the depleti on of nutrient cations and affect the acidification and trophic status of surface waters. Patterns of nitrate concentrations and losses were evaluated in four forested watersheds (East Bear Brook Watershed, Lea d Mountain, ME; Watershed 6, Hubbard Brook Experimental Forest, White Mountains, NH; Arbutus Watershed, Huntington Forest, Adirondack Mounta ins, NY; Biscuit Brook, Catskill Mountains, NY) located across the nor theastern United States. A synchronous pattern was observed in nitrate concentrations of drainage waters from these four sites from 1983 thr ough 1993. Most notably, high concentrations and high drainage water l osses followed an anomalous cold period (mean daily temperature -11.4 to -16 degrees C in December 1989) for all four sites. After high nitr ate losses during the snowmelt of 1990, nitrate concentrations and flu xes decreased at all sites. These results suggest that climatic variat ion can have a major effect on nitrogen flux and cycling and may influ ence temporal patterns of nitrate loss in a region.