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Concern over impacts of atmospheric nitrogen deposition to ecosystems in Rocky Mountain National Park, Colorado, has prompted the National Park Service, the State of Colorado Department of Public Health and Environment, the Environmental Protection Agency, and interested stakeholders to collaborate in the Rocky Mountain National Park Initiative, a process to address these impacts. The development of a nitrogen critical load for park aquatic resources has provided the basis for a deposition goal to achieve resource protection, and parties to the Initiative are now discussing strategies to meet that goal by reducing air pollutant emissions that contribute to nitrogen deposition in the Park. Issues being considered...
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Conclusions: Elevation, slope and the percentages of bogs and fens in a landscape influence the degree to which mid-boreal lakes are sensitive to acidic deposition orignating from nearby mining operations. Thresholds/Learnings: Synopsis: This study evaluates the acid sensitivity of lakes in Saskatchewan within ~300km of Fort McMurray. The study area is downwind of atmospheric emissions sources from regional oil sands mining operations and there is concern that the lakes may be threatened by acidification. A helicopter sampling program was implemented in late September 2007 and 2008 to measure 16 chemical variables (e.g., Ca, Mg, Na, pH) and 15 environmental variables (e.g., latitude, elevation, slope, percent bog,...
Using an estimated background nitrogen (N) deposition value of 0.5 kg N-ha-^yr"1 in 1900, and a 19-year record of measured values from Loch Vale (Colorado, USA; NADP site CO98), I reconstructedan N-deposition history using exponential equations thatcorrelatedwellwithEPA-reportedNO*emissionsfromColoradoandfromthesumof emissions of 11 western states. The mean wet N-deposition values for the period 1950-1964 was -1.5 kg Nha'^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...
    map background search result map search result map Chemical characteristics and acid sensitivity of boreal headwater lakes in northwest Saskatchewan. Chemical characteristics and acid sensitivity of boreal headwater lakes in northwest Saskatchewan.