Rocky Mountain National Park (ROMO) is experiencing a number of deleterious effects due to atmospheric nitrogen and sulfur compounds. These effects include visibility degradation, changes in ecosystem function and surface water chemistry from atmospheric deposition, and human health concerns due to elevated ozone concentrations.

The nitrogen compounds include both oxidized and reduced nitrogen. Emissions of nitrogen compounds need to be reduced to alleviate these deleterious effects. Various regulatory programs are underway to address emission reductions, many of which will be achieved from the most easily identified contributors to oxidized nitrogen related effects at the park.

STATEMENT OF THE PROBLEM

ROcky Mountain Atmospheric Nitrogen and Sulfur study (ROMANS)

Wet deposition patterns and trends

N deposition “hot spot” in northern Colorado Rockies

Current N deposition ~ 20x natural levels

Nitrogen deposition increasing at high elevation sites

Ammonium deposition increasing faster than nitrate

NADP 2004 Annual Summary

Burns (2003)Niwot Saddle NADP site

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.

ROMANS OBJECTIVES

The urban/industrial-agricultural interface

NOx

HNO3 + NH3 NH4NO3(p)+hv

Organic nitrogen?

VOC

If chemical transport models were “perfect” then all apportionment problems would best be addressed through the exercise of these models.BUT THEY ARE NOT! –especially when addressing species other than ozone and sulfate.

Apportionment Strategy

Apportionment Strategy (Weight of Evidence)• Concentration gradients.• Which way is the wind coming from?• Simple back trajectories.• Frequency with which the air mass passes

over source areas before it arrives at the receptor -residence time analysis.

• Trajectory receptor models.• Receptor models.• Chemical transport models.• Hybrid Models.

Dinosaur

Gore Pass

Grant, NE

Springfield

BrushLoch Vale

Core SiteLyons

Timber Creek Beaver Meadows

STUDY DESIGN

CORE SITE

Time series of PILS and IMPROVE sulfate and nitrate

NH4NO316%

POM15%

blac1%

bcm22%

babsf5% babsc

0%

(NH4)2(SO4)41%

Vr= 40 km

Spring atmospheric scattering estimations

(NH4)2(SO4)18%

NH4NO35%

POM50%

SOIL7%

blac2%

BSCM8%

babs_fine8%

babs_coarse2%

Vr=27 KM

Summer atmospheric scattering estimations

Comparison of visibility on clear day and a day with Vr=25 km

Wet Concentration and Deposition (Spring)

Wet Concentration and Deposition (Summer)

Relative contributions of individual N deposition pathways to total measured N deposition

SUMMERTotal Dep = 6228 ug/m2

SPRINGTotal Dep=3326 ug/m2

Concentration Gradients

Spring overviewConcentrations lower in mountainsGases dominate at eastern and western sites

Highest ammonia at Brush in NE Colorado

Particles dominate in mountains

Summer overview

Concentrations higher than in springHighest concentrations again east of RMNPIncreasing N gas importance in mountains

Concentration Gradient Across Monitoring Network

Concentration Gradient Across Rocky Mt NP

Colorado Front Range Upslope Events

• Easterly Winds Transport Airmasses from Front Range and Further East to Rocky Mountain

Wind Direction for a Major Episode

Rain

WIND DIRECTION AND PARTICLE CONCENTRATIONS

Simple Trajectory Analysis

Nitrate Wet Deposition Flux [ug/m2/Day]

0

2000

4000

6000

8000

10000

12000

8/17 8/18 8/19 8/20 8/21 8/22 8/23 9/6 9/8

MS1 MS2 BM LV HV RB RK AC LI

However, most of the upslope events were associated with precipitation events – accounts for between 80-90% of the deposition.

Upslope trajectories occurred: Aug 20-22, Sept 2-3, 6, 8

Statistical Analysis of Many Trajectories (Residence Time)

NH3 Spring

NH3 SummerNH3 Summer

NOx Spring

Apportionment of Gas/Particle Species Using Modeled Tracer

Existing CAMx 36 km and 12 km nested grids, and approximate location of 4 km grid

National Park ServiceU.S. Department of the Interior

Cooperative Institute for Research in the AtmosphereColorado State University

d1

d2

d3

SOURCE REGIONS for CAMX RUNSNH3

SO2

NOx

ikjikjj

ki Sa=C ε+∑Where

k = 1 ... m, the number of observations,i = 1 ... n, the number of sources contributing to receptor,j = 1 ... N, the number of source region vectors,Cki = concentrations of ammonia from source i for time period k,akj = time weighting functions, andSji = source vectors.εik = error term including random and lack of fit error.

The receptor model

( ) ∑ Φ=j

jkjkkC α

Ck = the measured hourly aerosol concentrationsΑjk = the regression coefficientsΦjk = the average of modeled concentrations arriving at the receptor from sources areas grouped according to eigenvectors, v

Spring NH3/NH4 Northeast Region Spring NH4 Region 7

Spring NH3/NH4 Region 8 Spring NOX Region 2

Grouping of Source Regions

APPORTIONMENT TO SOURCE REGIONS(NH3 SPRING)

APPORTIONMENT TO SOURCE REGIONS(NH3 SUMMER)

APPORTIONMENT TO SOURCE REGIONS(HNO3 SPRING)

Average Apportionments (gas/particle concentrations)

Average SpringApportionments

(wet deposition)

Spring Average Wet NH4 Fractional Contribution

Denver25%

Western CO0%

Northeastern CO44%

Estes 3%

local 4%

Other14%

East WY8%

Calif 2%

Spring Average Wet NO3 Fractional Deposition

Denver51%

Western CO0%

Northeastern CO

22%

Estes 11%

Other5%

NW CO 2%

Four Corners 1%

East WY7%

Calif 1%

Average SummerApportionments

(wet deposition)

Summer Average SO4 Fractional Wet Deposition

Denver2%

Local14%

NW CO 3%

Calif 36%

S Nevada3%

NGS 1%

Four Corners14%

East WY2%

Other13% Western CO

5%Estes

7%

Summer Average NH4 Fractional Wet Deposition

Denver1%

Western CO24%

Northeastern CO6%

Estes 4%

Local29%

Calif 5%

SW WY 5%

East WY1%

Other25%

Summer Average NO3 Fractional Wet Deposition

Denver7%

Western CO12%

Este2%

Loca6%

NW CO5%

Calif 14%

S Nevada9%

NGS 1%

Four Corners

9%

SW WY 2%

East WY3%

Other30%

SUMMARY A substantial portion of ammonia, ammonium, nitrate, and nitric acid originates in the state of Colorado.Sulfur species tend to more associated with longer range transport and come from outside the state.More sources contribute during the summer than spring.Natural emissions of ammonia appear to contribute significantly to ammonia and ammonium concentrations and deposition.During the Spring during upslope conditions northeastern Colorado contributes most of the ammonia and wet deposited ammonium.The town of Estes Park appears to contribute significantly to nitric acid and nitrate during the spring time frame.During the summer sources in California and off the coast of California contribute significantly.

END

FOOD FOR THOUGHT?

Concerns about N deposition

Low capacity to sequester atmospheric N depositionN enrichment and shifts in diatom communities in alpine lakesN enrichment in organic soil layer and Engelmann spruce needles on eastern slope

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

Contribution of Fires to ?

Wildfire

Prescribed Fire Residential Wood Burning

Agricultural Fire

Role of Ammonia?Direct ecosystem effectsResponse of a basic gas neutralizing acidity in particles and gases. (neutralization of acidic sulfate aerosols – reaction with nitric acid vapor – reactions with organic salts) Response of PM formation can be dislocated from where ammonia reduction first took place.Ammonia deposition via cloud uptake and subsequent rain, dry deposition in the gas vs particle phase have vastly different time scales that leads to different lifetimes and particle response.

Standard Receptor modelsReceptor models typically rely on measured mass concentrations of particles and gases at a receptor site –typically yield relative contributions of sources to mass/extinction at one point in time.

CMBPMFUNMIXEOF (across species for one time)Etc

Other types of receptor techniques apportion, on the average, one species to sources using multiple receptor sites.

EOF (one species across space and time)Etc.

Time series of PILS data

Increasing Wet Nitrogen Deposition?

Wet nitrate concentration deposition trends

Wet ammonium concentration deposition trends

J B k t l G i I tit t f T h l

Meteorology

Air Quality

Source‐oriented Model(3D Air‐quality Model)

(CMAQ, CAMx)

Receptor (monitor)

Receptor Model(CMB, PMF)

Source  Impacts

Chemistry

Receptor model C=f(F,S)

Source‐compositions (F)

Integrate measurements and deterministically modeled parameters into a receptor framework –usually referred to as a hybrid model

Number size distribution used for estimatingvisibility effects and POM mass

Semi continuous POM concentrations derived from number size distribution

Summer Mean SD Min Max

SI 0.83 0.22 0.35 1.62

SO4I 0.68 0.17 0.27 1.21

SO4U 0.65 0.17 0.28 1.20

SO4PIL 0.84 0.20 0.39 1.47

Spring Mean SD Min Max

SI 0.56 0.30 0.13 1.40

SO4I 0.49 0.28 0.11 1.28

SO4U 0.51 0.27 0.11 1.27

SO4PIL 0.57 0.40 0.12 1.81

Timeline of major species concentrations and flux measured in precipitation during the spring and summer field campaigns

Time evolution of cumulative precipitation and wet deposition of major solute species for two time periods

Trajectories and Relative Source Contributions

Spring Apportionments (wet deposition)

Summer Apportionments (wet deposition)

The Data

Deposition fluxes broken down for each species bydry gaseous, dry particle, and wet

Instrument Measurement Time Resolution Notes Core Site Secondary Sites Satellite Sites

URG annular denuder/filter-pack sampler

PM2.5 inorganic ionsGaseous NH3, HNO3, and SO2

24 hr X X Beaver Meadows, Brush, Dinosaur, Grant (NE), Springfield, Timber Creek

R&P Partisol denuder/filter-pack sampler

PM2.5 inorganic ionsGaseous NH3, HNO3, and SO2

Operated only during last several days of summer campaign

Alpine

Particle-into-liquid sampler (PILS) – IC

PM2.5 inorganic ions 15 min/2 hr 15-min on-line operation at core site; 2-hr off-line with sample archival at secondary sites; spring only at Lyons

X X

Sunset OC/EC analyzer

PM2.5 OC and EC 1–2 hr X

IMPROVE sampler PM2.5 and PM10 mass, ions, elements, H, and OC/EC

24 hr X

MOUDI impactor Inorganic ion size distributions

48 hr 8 stages from ~0.02-18 µm aerodynamic diameter; samples archived

X Lyons (spring only)

Continuous gas monitors

SO2, NOx, NH3, CO, O3 1 min X

Wet-only auto precip sampler

Precipitation Event/daily

X Lyons (spring)Gore Pass (summer)

Sub-event precipitation sampler

Precipitation Sub-event (e.g., hourly)

X X

Open bucket precipitation collector

Precipitation Daily Changed daily at most sites; 48 hr change typical at

X X X

MONITORED SPECIES

Particle-into-liquid sampler (PILS) – IC

PM2.5 inorganic ions 15 min/2 hr 15-min on-line operation at core site; 2-hr off-line with sample archival at secondary sites; spring only at Lyons

X X

Sunset OC/EC analyzer

PM2.5 OC and EC 1–2 hr X

IMPROVE sampler PM2.5 and PM10 mass, ions, elements, H, and OC/EC

24 hr X

MOUDI impactor Inorganic ion size distributions

48 hr 8 stages from ~0.02-18 µm aerodynamic diameter; samples archived

X Lyons (spring only)

Continuous gas monitors

SO2, NOx, NH3, CO, O3 1 min X

Wet-only auto precip sampler

Precipitation Event/daily

X Lyons (spring)Gore Pass (summer)

Sub-event precipitation sampler

Precipitation Sub-event (e.g., hourly)

X X

Open bucket precipitation collector

Precipitation Daily Changed daily at most sites; 48-hr change typical at Brush and Grant (NE)

X X X

Met station T, RH, WD, WS, Precip, SR,BP

1–5 min 1 min core; 5 min secondary; hourly data only 1st week of spring study at core site

X X

Particle sizing rack Aerosol particle size distributions

15 min Differential mobility particle sizing (DMPS) system, optical particle counter (OPC), aerodynamic particle sizer (APS); ~0.05–10 µm diameter

X

Optec nephelometer Particle light scattering 5 min Open air; no RH control or size cut

X X

Summary of IMPROVE (μg/m3)

PM2.5 Summer

LAC4%

SOIL18%

Ammonium Sulfate

16%

Ammonium Nitrate

3%

POM59%

SEASALT0%

Coarse Summer

LAC1%SOIL

69%

Ammonium Nitrate

3%

Ammonium Sulfate

1%

SEASALT0%

POM26%

Variable Mean Std dev Fraction Minimum Maximum

FM 5.57 2.18 0.98 1.15 12.46

FMrecon 5.47 2.11 1.37 12.39

(NH4)2SO4 0.90 0.26 0.16 0.21 1.67

NH4NO3 0.16 0.15 0.03 0.04 0.53

POM 3.20 1.62 0.58 0.94 9.10

LAC 0.24 0.10 0.04 0.06 0.54

SOIL 0.97 0.53 0.18 0.04 1.84

SEASALT 0.00 0.00 0.00 0.00 0.01

Variable Mean Std dev Fraction Minimum Maximum

CM 4.14 2.46 1.19 -0.55 9.03

CMrecon 4.94 2.45 0.59 9.46

(NH4)2SO4 0.03 0.04 0.01 -0.05 0.12

NH4NO3 0.16 0.11 0.03 0.05 0.48

POM 1.30 0.45 0.26 0.17 2.03

LAC 0.06 0.06 0.01 -0.03 0.23

SOIL 3.36 2.15 0.68 -0.28 7.41

SEASALT 0.02 0.04 0.00 0.00 0.19

CM/2

Time series of semi-continuous particle species

Nitrogen deposition totals by various species and pathwaysin order of contribution to total N deposition

Trajectories for two time periods when ammoniaconcentrations were elevated