Nitrogen Deposition at Rocky Mountain National Park: the RoMANS

Study

Mike BarnaBill MalmBret SchichtelKristi Gebhart

Air Resources Division National Park Service

National Park ServiceU.S. Department of the Interior

Ozone and NOx in the West MeetingNovember 11, 2009

Santa Fe, NM

RoMANS

• Nitrogen deposition at Rocky Mountain NP has exceeded a critical load of 1.5 kg/ha/yr

• RoMANS: Rocky Mountain Atmospheric Nitrogen and Sulfur Study

• Field measurement campaigns conducted in spring and summer of 2006

• Which source regions / source types are contributing to N deposition at RMNP?

RoMANS participants

• FEDERAL GOVERNMENT AGENCIES• NPS • NOAA• USGS• USFS• EPA

• STATE OF COLORADO• Colorado State University• Colorado Department of Public Health and Environment

• CONTRACTORS• Air Resource Specialists• University of California• Desert Research Institute• Research Triangle Institute

RoMANS objectives

•Characterize the atmospheric concentrations of sulfur and nitrogen species in gaseous, particulate and aqueous phases (precipitation and clouds) along the east and west sides of the Continental Divide (Organic Nitrogen?)

– GAS: NH3, R-NH2, NOX(NO+NO2), NOY(HNO3, PAN, etc)

– PARTICLE: NH4, NO3, ORGANICS (reduced and oxidized)?

– WET (rain, snow, and clouds): NH4, NO3, ORGANICS (reduced and oxidized)?

•Identify the relative contributions to atmospheric sulfur and nitrogen species in RMNP from within and outside of the state of Colorado.

•Identify the relative contributions to atmospheric sulfur and nitrogen species in RMNP from emission sources along the Colorado Front Range versus other areas within Colorado.

•Identify the relative contributions to atmospheric sulfur and nitrogen species from mobile sources, agricultural activities, large and small point sources within the state of Colorado.

•Characterize the atmospheric concentrations of sulfur and nitrogen species in gaseous, particulate and aqueous phases (precipitation and clouds) along the east and west sides of the Continental Divide (Organic Nitrogen?)

– GAS: NH3, R-NH2, NOX(NO+NO2), NOY(HNO3, PAN, etc)

– PARTICLE: NH4, NO3, ORGANICS (reduced and oxidized)?

– WET (rain, snow, and clouds): NH4, NO3, ORGANICS (reduced and oxidized)?

•Identify the relative contributions to atmospheric sulfur and nitrogen species in RMNP from within and outside of the state of Colorado.

•Identify the relative contributions to atmospheric sulfur and nitrogen species in RMNP from emission sources along the Colorado Front Range versus other areas within Colorado.

•Identify the relative contributions to atmospheric sulfur and nitrogen species from mobile sources, agricultural activities, large and small point sources within the state of Colorado.

Concerns about N deposition

• Low capacity to sequester atmospheric N deposition

• N enrichment and shifts in diatom communities in alpine lakes

• N enrichment in organic soil layer and Engelmann spruce needles on eastern slope

See Fenn et al. (2003) for review of N deposition ecological effects

Increasing wet N deposition

Wet ammonium concentration deposition trends

Wet nitrate concentration deposition trends

Sources of reduced/oxidized N

Vegetation Feedlots-Fossil Fuel Combustion Organic N

Wild animals –Ecosystem respiration

Feedlots – FertilizerMobile & Area Sources

NH3 NH4

Soil ReleaseLightningWild fire

Fossil-Fuel Combustion (power plants- mobile sources-oil and gas) Fertilizer, Prescribed fire

NO2 NO3

Naturally Occurring AnthropogenicCompound

• What happens to emitted NOx & NH3?

• NH3: rapid deposition, NH3 NH4+, no gas-phase oxidation

• NOx: complicated photochemistry, HNO3 NO3-, some species rapidly deposit (HNO3, NO.)

NH3 NOx

NH3 and NOx emissions

2006 v. 2012 NOx emissions in UBAQS

RoMANS field sites

Dinosaur

Gore Pass

Grant, NE

Springfield

BrushLoch Vale

Core SiteLyons

Timber Creek Beaver Meadows

Core site at RMNP

RoMANS period typical?

Spring (Mar 25 - Apr 30)

0

0.2

0.4

0.6

0.8

1

1.2

N_NH4 N_NO3 Total N S_SO4

Co

nc

en

tra

tio

n (

mg

/l)

Climatology (2000-05) ROMANS (2006)

Summer (Jul 6 - Aug 11)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

N_NH4 N_NO3 Total N S_SO4

Co

nc

en

tra

tio

n (

mg

/l)

Climatology (2000-05) ROMANS (2006)

Spring (Mar 25 - Apr 30)

0

0.1

0.2

0.3

0.4

0.5

0.6

N_NH4 N_NO3 Total N S_SO4

Co

nc

en

tra

tio

n (

mg

/l)

Climatology (2000-05) ROMANS (2006)

Summer (Jul 6 - Aug 11)

00.10.20.30.40.50.60.70.80.9

N_NH4 N_NO3 Total N S_SO4

Co

nc

en

tra

tio

n (

mg

/l)

Climatology (2000-05) ROMANS (2006)

Loch Vale

Beaver Meadows

RoMANS trajectories

Rocky Mountain National Park Concentration Weighted Residence Time

Mar 27, 2006 - Aug 11, 2006Weighted by N.TotDep.BM.kghayr

Includes Months: 3,4,7,8

Heights = 0 - 8860 m, input = Hy47 EDASGDAS , Traj Len = 5 days, 100 m start

< 0.00050.0005 to 0.0010.001 to 0.0020.002 to 0.0040.004 to 0.0080.008 to 0.0160.016 to 0.0320.032 to 0.0640.064 to 0.128> 0.128

Percent of Endpoints

All days from January 1, 2000 – December 31, 2007

Deposition Weighted Residence Time

All days from During RoMANS study period

Wind direction and concentration

Apportionment strategy

• Concentration gradients• Which way is the wind coming from?• Simple back trajectories• Residence time analysis• Trajectory receptor models• Receptor models• Chemical transport models• Hybrid Models

NOx

NH3

Wet Deposition (Spring)14000 35

30

25

20

15

10

5

0

12000

10000

8000

6000

4000

2000

0

3/2

6

3/2

9

4/1

5

4/1

74

/18

4/2

34

/24

4/2

8We

t D

ep

osit

ion

N o

r S

(g

/m2 )

Precip

ita

tio

n (

mm

)

SO4 NO3 NH4 DON mmprecip

Spring Average Wet NH4 Fractional Contribution

Denver12%

Northeastern CO

62%

Other17%

Estes 1%

East WY7%

Calif 1%

Spring Average Wet NO3 Fractional Deposition

Denver52%

Other39%

Northeastern CO1%

NW CO 2%

East WY6%

Summer Average NH4 Wet Dep

Denver2%

Western CO24%

Northeastern CO7%

Estes 1%

Local32%

Other24%

Calif 7%

East WY2%

SW WY 1%

Summer Average NO3 Wet Dep

Denver10%

Western CO3%

Northeastern CO3%

Local8%

NW CO 5%

Calif 17%S Nevada

15%

NGS 2%

Four Corners8%

SW WY 2%

East WY3%

Other21%

Estes 3%

14000 35

30

25

20

15

10

5

0

12000

10000

8000

6000

4000

2000

0

7/0

67/0

77/0

87/0

9

7/1

1

7/1

5

7/1

7

7/1

97/2

0

7/2

37/2

47/2

57/2

6

7/3

07/3

1

8/0

3

8/0

5

8/0

7

8/1

08/1

1We

t D

ep

osit

ion N

or S

(g/m

2 )

Pre

cip

itatio

n (m

m)

SO4 NO3 NH4 DON mmprecip

Wet Deposition (Summer)

Wet + Dry Deposition for Spring and Summer (in state vs out of state)

20

measured species:

‘missing N’ species:

‘Missing’ nitrogen

N dry deposition of Rocky Mountain NP

• N dry deposition at RMNP based on CASTNet

• Only three N species are typically ‘measured’ for dry deposition: NH4+, NO3- and HNO3

• What happens when we consider the dry deposition of total N at RMNP?

• Oxidized N (the NOy budget):

• NOx, HNO3, NO3-, PAN + other organic nitrates, HONO, nitrate radical + N2O5

• Reduced N:

• NH3, NH4+

• Simulate this ‘missing N’ with CAMx

Modeled dry deposition at RMNP

N-NOx4%

N-PAN3%

N-NxOy10%

N-Org N2%

N-NH328%

N-HONO0%

N-PNO30%

N-HNO353%

N-PNH40%

Yearly CAMx and CASTNet estimates of dry deposited N at RMNP for 2002

0.0

0.5

1.0

1.5

2.0

2.5

[HNO3,NO3,NH4] [HNO3,NO3,NH4] [Total N]

CASTNet CAMX CAMX

N D

ry D

epo

siti

on

[kg

/ha/

yr]

N-PNO3

N-PNH4

N-NOx

N-PAN

N-NxOy

N-Org N

N-NH3

N-HONO

N-HNO3

New NHx measurements

• A new module to the IMPROVE sampler• Measures both NH3 and NH4+• Proposed sites (likely to change):

• Chiricahua AZ• Bandelier NM• Mesa Verde CO• Rocky Mtn CO• Brooklyn Lake WY• Yellostone WY• Glacier MT• Teddy Rosevelt ND• Wind Cave SD• Craters of  the Moon ID

What we found

• A substantial portion of deposited Nitrogen originates from within the state of Colorado (about a 55:45 split)– Of the reduced nitrogen about 70% comes from

Colorado sources– Of the Oxidized nitrogen the split is closer to 40% from

Colorado sources

• During the Spring upslope conditions cause most of the N deposition.– Associated with large single deposition episodes– Reduced nitrogen is primarily from northeastern

Colorado – Oxidized nitrogen is primarily form Denver and its

associated sources

What we found (cont’d)

• During the summer deposition episodes are smaller but more frequent so that total deposition is greater than during the Spring. – Sources of reduced nitrogen are about equally split

between northeastern and western Colorado. Local emissions may also contribute significantly.

– Sources of oxidized nitrogen come from oil and gas and power plants in the 4-corners region and general transport form the southwest

• In general about ½ of total nitrogen deposition comes from the east and about ½ from the west

• More diverse sources contribute during the summer than spring.

The end

Process analysis in CAMx

Order Process Information Units 1 Initial concentration μmole/m3

2 Gas phase chemistry μmole/m3

3 Area emissions μmole/m3

4 Point source emission μmole/m3

5 Plume-in-rid change μmole/m3

6 West boundary advection μmole/m3

7 East boundary advection μmole/m3

8 South boundary advection μmole/m3

9 North boundary advection μmole/m3

10 Bottom boundary advection μmole/m3

11 Top boundary advection μmole/m3

12 Dilution in the vertical μmole/m3

13 West boundary diffusion μmole/m3

14 East boundary diffusion μmole/m3

15 South boundary diffusion μmole/m3

16 North boundary diffusion μmole/m3

17 Bottom boundary diffusion μmole/m3

18 Top boundary diffusion μmole/m3

19 Dry deposition μmole/m3

20 Wet deposition μmole/m3

21 Heterogeneous chemistry μmole/m3

22 Final concentration μmole/m3

23 Units conversion ppm/(μmole/m3) 24 Average cell volume m3

Process analysis: ammonia

‘Local’ dry deposition of ammonia