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Synchronicity of long-term nitrate patterns in forested catchments across the northeastern U.S.
Citation:
STODDARD, J. L. AND G. P. OELSNER. Synchronicity of long-term nitrate patterns in forested catchments across the northeastern U.S. Presented at ASLO/NABS Meeting, Santa Fe, NM, June 06 - 11, 2010.
Impact/Purpose:
Nitrogen movement through minimally-disturbed catchments can be affected by a variety of biogeochemical processes, climatic effects, hydrology and in-stream or in-lake processes.
Description:
Nitrogen movement through minimally-disturbed catchments can be affected by a variety of biogeochemical processes, climatic effects, hydrology and in-stream or in-lake processes. These combine to create dizzying complexity in long-term and seasonal nitrate patterns, with adjacent catchments often exhibiting very different nitrate behavior. We examined long-term (1993-2008) patterns of nitrate concentrations in 60 forested catchments from U.S. EPA’s Long-Term Monitoring Project. Normalized and smoothed nitrate patterns exhibit large-scale (i.e., regional) patterns amid all of their complexity. Concentration peaks occur at nearly ass sites in 1990 and again in 1997. After 1997, behavior is more varied, but still shows groups of sites with synchronous peaks in concentrations. The 1990 peak has been attributed (Mitchell et al. 1996) to an exceptionally cold winter, with widespread soil freezing. Although climate is an obvious suspect for causing such regional behavior, it is difficult to identify any climatic patterns that explain those of nitrate.