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December 5, 2023

Excess reactive nitrogen from vehicle emissions has the potential to negatively impact ecosystems, through increased soil acidification, biodiversity loss, or other cascading effects. A new paper out in the journal Water, Air, Soil Pollution describes an unexpected finding from a study of local vehicle emissions and nitrogen deposition in Rocky Mountain National Park. 

satellite imagery of Bear Lake corridor with inset map of rocky mountain national park. Study sites marked in red and blue.
(a) This study took place near the parking lot for Bear Lake, a highly visited area of Rocky Mountain National Park. Open, grassland sites are shown in blue, with a closeup view in (b); throughfall sites are shown in orange, with a closeup view in (c). Figure from Rocci and others (2023).


While others have found evidence that vehicle nitrogen emissions are deposited in soils and vegetation with decreasing concentrations farther away from the source (such as a large parking lot), the authors found no influence of road proximity on inorganic nitrogen deposition in throughfall or grassland (open) sites, possibly due to terrain complexity. These findings do not negate vehicles as a local source of nitrogen emissions, but suggest elevated nitrogen deposition adjacent to busy roads cannot be assumed for complex terrains.

The paper, "Proximity to roads does not modify inorganic nitrogen deposition in a topographically complex, high traffic, subalpine forest (IP-144811)" has implications for managing sources of pollution in Rocky Mountain National Park. The paper DOI is 10.1007/s11270-023-06762-2


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