Nitrogen Deposition over the US

Raluca Ellis, Fabien PaulotDaven Henze, Daniel Jacob

Harvard University, U. Colorado Boulder

AQAST 3 meeting, June 13, 2012

Funding: AQAST, HUCEAir Quality Management Partner: Bret Schichtel, NPS

Nitrogen in the Nation’s Rain, NADP, 2000

Pathways of Reactive Nitrogen

NH3

NOx

CL = 1.5 wet kg N ha-1 a-1 alpine lakes CL = 3 - 8 kg N ha-1 a-1 forest/trees

CL = 3.0 kg N ha-1 a-1 lichens Pardo et al., Ecol Appl, 2011

Quantify relationship between deposition and ecosystem response = critical loadSpecific to certain resource and defined harmful effect

Total nitrogen deposition to the US (wet + dry)

GEOS-Chem total nitrogen deposition (2006-2008 annual mean)Nested North American model 0.5o x 0.667o resolution

Evaluated using NADP, CASTNet see Zhang et al., ACP, 2012

Total nitrogen deposition to the US (wet + dry)

GEOS-Chem total nitrogen deposition (2006-2008 annual mean)Nested North American model 0.5o x 0.667o resolution

Evaluated using NADP, CASTNet see Zhang et al., ACP, 2012

Parks exceeding critical load nclude Rocky Mountain, Joshua Tree, Great Smoky MountainsMany western parks near critical load

Zhang et al., ACP, 2012

Source Attribution of Reactive Nitrogen

Generally less than 10% but up to 30% near borders

Higher than average in areas affected by lightning and wildfires

NOx emissions are going down but NH3 is increasing

Will N deposition decrease or increase?Will source attribution change?

Can critical load goals be met?

Total N emissions 2050 – 2005 RCP 2.6

RCP future emission scenarios

Total N emissions 2050 – 2005 RCP 8.5

World emissions