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Hindcasting nitrogen deposition to determine an ecological critical load

January 1, 2006

Using an estimated background nitrogen (N) deposition value of 0.5 kg N·ha−1·yr−1 in 1900, and a 19-year record of measured values from Loch Vale (Colorado, USA; NADP site CO98), I reconstructed an N-deposition history using exponential equations that correlated well with EPA-reported NOx emissions from Colorado and from the sum of emissions of 11 western states. The mean wet N-deposition values for the period 1950–1964 was ~1.5 kg N·ha−1·yr−1, corresponding to the reported time of alteration of diatom assemblages attributed to N deposition in alpine lakes in Rocky Mountain National Park (USA). This value becomes the critical load defining the threshold for ecological change from eutrophication. Thus if an N-deposition threshold for ecological change can be identified, and the date at which that threshold was crossed is known, hindcasting can derive the amount of atmospheric deposition at the time of change, at least for alpine lakes. Independent support for the technique and the deposition amount comes from experimental studies, ecosystem modeling, and paleolimnological records from northern Wyoming (USA).

Publication Year 2006
Title Hindcasting nitrogen deposition to determine an ecological critical load
DOI 10.1890/1051-0761(2006)016[0433:HNDTDA]2.0.CO;2
Authors Jill Baron
Publication Type Article
Publication Subtype Journal Article
Series Title Ecological Applications
Index ID 1015121
Record Source USGS Publications Warehouse
USGS Organization Fort Collins Science Center