Ammonia and its influence on nitrogen deposition and fine particle formation

Jeffrey L. Collett, Jr. Atmospheric Science Department, Colorado State University

Acknowledgments • People

– CSU: Katie Benedict, Yi, Li, Tony Prenni, Ashley Evanoski-Cole, Derek Day, Florian Schwandner, Suresh Raja, Taehyoung Lee, Amy Sullivan, Kip Carrico, Sonia Kreidenweis

– NPS: Bret Schichtel, William Malm – ARS: Mark Tigges, John Molenar, Stephen Holcomb, Cassie Archuleta,

Lincoln Sherman – Shell: Angela Zivkovich – UC Davis: Chuck McDade, Jose Mojica, Mark van de Water – RTI: Eva Hardison, David Hardison

• Funding – U.S. National Park Service – U.S. Department of Agriculture – Shell Exploration and Production Company

Reactive nitrogen emissions

• Nitrogen oxides – NOx = NO + NO2 – Formed by high temperature

reaction of N2 and O2

– NOx reacts in the atmosphere to form nitric acid (HNO3) and other species

• Ammonia (NH3) • Livestock and fertilizer are

largest sources

NH3 emission sources

USEPA (2004)

USEPA

Particulate atmospheric nitrogen

• Ammonium nitrate – NH3(g) + HNO3(g) <=>

NH4NO3(p) – Sensitive to temperature

and relative humidity

• Ammonium sulfate – 2 NH3 + H2SO4

=>(NH4)2SO4

• Particles ~200-600 nm in diameter – Long lifetimes in

atmosphere (several days) – Important cause of haze

Denver brown cloud (Denver Post)

Reactive nitrogen deposition

• Wet deposition – Precipitation scavenges gases

and particles and deposits them on surface

– Easier to measure

• Dry deposition – Difficult/expensive to measure – Estimate as product of

measured concentration and modeled deposition velocity

– Gas/particle partitioning is key • Vd,NH3 >> Vd,NH4+

• Vd,HNO3 >> Vd,NO3-

Hand et al. (2011) IMPROVE report

HISTORICAL CHANGES IN REACTIVE N WET DEPOSITION

Nitrate Ion Wet Deposition

http://nadp.sws.uiuc.edu/data/

1995-97 1984-86

2003-05 2007-09

Ammonium Ion Wet Deposition

http://nadp.sws.uiuc.edu/data/

1995-97 1984-86

2003-05 2007-09

Changes in NH4+ wet deposition

NH4+

Lehmann et al., 2005

Changes in NO3- wet deposition and

NOx emissions

Lehmann and Gay, 2011

NO3- NOx

Change in NH4+ fraction in U.S. wet inorganic N deposition

Li et al., in prep

THE IMPORTANCE OF NH3 FOR N DEPOSITION AND PARTICLE FORMATION: A FEW EXAMPLES

Concerns about nitrogen deposition

RoMANS (Rocky Mountain Airborne Nitrogen and Sulfur) Study

• Major field studies – Spring

and Summer 2006

– 2008-09

RoMANS 2006 core site wet deposition

•Spring flux dominated by single event -- summer flux contributed by several events •Substantial oxidized, reduced, and organic N

Spring overview

• Strong concentration gradient

• Low concentrations west of RMNP

• High concentrations east of RMNP

• Ammonia peaks in NE Colorado

0

20

40

60

80

100

120

140

3/29 3/30 3/31 4/1 4/2 4/3 4/4 4/5 4/6 4/7 4/8 4/9 4/10 4/11 4/12 4/13 4/14 4/15 4/16 4/17 4/18 4/19 4/20 4/21 4/22 4/23 4/24 4/25 4/26 4/27 4/28 4/29 4/30 5/1

Date

Con

c.(n

eq/m

3)

SO4= NO3- NH4+

RMNP particle timelines

• Highly variable concentrations • Pollutant mix (sulfate, nitrate, and ammonium) varies

between episodes

Sulfate dominated

Mix of sulfate and

nitrate

Nitrate dominated

A closer look… • Ammonium nitrate episodes associated with upslope flow

from east of RMNP

0

20

40

60

80

100

120

140

4/20 4/21 4/22 4/23 4/24 4/25 4/26 4/27

Date

neq

/m3

0

90

180

270

360

WD

(D

eg

ree)

SO4= NO3- NH4+ WD 30 per. Mov. Avg. (WD)

precip

Annual mountain to plains gradient

0.0

0.2

0.4

0.6

0.8

1.0

Con

cent

ratio

n (µ

mol

/m3 )

NH3

Brush Loveland RMNP

0.00

0.01

0.02

0.03

0.04

11/1 12/1 1/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 10/1 11/1 12/1

Con

cent

ratio

n (µ

mol

/m3 )

HNO3

RMNP reactive N concentrations

0.00.20.40.60.81.01.21.41.61.82.0

11/1

1/08

11/2

5/08

12/9

/08

12/2

3/08

1/6/

09

1/20

/09

2/3/

09

2/17

/09

3/3/

09

3/17

/09

3/31

/09

4/14

/09

4/28

/09

5/12

/09

5/26

/09

6/9/

09

6/23

/09

7/7/

09

7/21

/09

8/4/

09

8/18

/09

9/1/

09

9/15

/09

9/29

/09

10/1

3/09

10/2

7/09

11/1

0/09

Con

cent

ratio

n (µ

g/m

3) NH4

NH3

Benedict et al., 2013a

0.0

0.5

1.0

1.5

2.0

2.5

3.0

11/1

1/08

11/2

5/08

12/9

/08

12/2

3/08

1/6/

09

1/20

/09

2/3/

09

2/17

/09

3/3/

09

3/17

/09

3/31

/09

4/14

/09

4/28

/09

5/12

/09

5/26

/09

6/9/

09

6/23

/09

7/7/

09

7/21

/09

8/4/

09

8/18

/09

9/1/

09

9/15

/09

9/29

/09

10/1

3/09

10/2

7/09

11/1

0/09

Con

cent

ratio

n (µ

g/m

3) NO3

HNO3

RMNP seasonal dry deposition budget

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Jan.

Feb.

Mar

.

Apr

.

May

June

July

Aug

.

Sept

.

Oct

.

Nov

.

Dec

.

Dep

ositi

on (k

g N

/ha)

Dry HNO3 Dry NH3 Dry NO3 Dry NH4

• Ammonia deposition most important; spring and summer peaks

Benedict et al., 2013a

RMNP N deposition – annual budget

• Wet deposition biggest contributor to N deposition

• Dry deposition

strongly dominated by NH3

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Dry NO3

Dry ON

Dry NH4

Dry HNO3

Wet ON

Dry NH3

Wet NO3

Wet NH4

Total Deposition 11/08-11/09 (kg N/ha)

Particle ON only

Benedict et al., 2013a

The 2011 Grand Teton Reactive Nitrogen Deposition Study

(GrandTReNDS)

Craters of the Moon AMoN

Driggs (DR)

Clarisse et al. (2009) IASI satellite NH3

Selected GrandTReNDS sites

Precipitation Collection Met Station

URG

AMS, PILS, Gas Rack, SMPS, OPC, APS,

MOUDI

Weekly NH3 Passive

Grand Targhee

Driggs, ID (west)

GTNP East

Atmospheric Concentrations

0.0

1.0

2.0

3.0N

H3

(µg/

m3 )

Driggs

Lower GrandTargheeNOAA ClimateCenterUpper GrandTarghee

0.0

0.5

1.0

1.5

HN

O3

(µg/

m3 )

HNO3

0.00.51.01.52.0

NH

4+ (µ

g/m

3 ) NH4

+

0.00.51.01.52.0

1-A

pr

15-A

pr

29-A

pr

3-M

ay

27-M

ay

10-J

un

24-J

un

8-Ju

l

22-J

ul

5-A

ug

19-A

ug

2-Se

p

16-S

ep

30-S

ep

NO

3-

(µg/

m3 )

NO3-

NH3

Benedict et al., JGR, 2013b

GrandTReNDS deposition budgets

• Reduced nitrogen comprises 50-80% of the N deposition budget – even more important here

than in Rocky Mountain National Park

Benedict et al., JGR, 2013b

Long-term measurements of the NHx-NOx-SOx system in Boulder, WY – one of the largest

U.S. natural gas producing regions

CSU, Air Resource Specialists, Shell

Reduced nitrogen shows typical summer max

Oxidized nitrogen shows unusual winter max tied to

winter photochemical smog

How much NH3 is available to react with NOx oxidation products to generate fine particles and lead to haze

formation?

Li et al., Atmos. Env., 2013

NH3(g) + NH4+(p) HNO3(g) + NO3

-(p)

Li et al., Atmos. Env., 2013

• Active winter photochemistry produces high ozone and nitric acid • Winter fine particle nitrate formation limited by ammonia availability

https://www.dmr.nd.gov/oilgas/

Oil Production in North Dakota

Bakken Shale Oil and Gas Development

Air quality in the Bakken shale region

Winter fine particle nitrate increasing in parts of western U.S.

Winter 2013 study conducted across region of

extensive oil well drilling to examine air quality impacts

From J. Hand

05

101520 Knife River (KNRI)

05

101520 Medicine Lake (MELA)

Bakken Particle Composition Co

ncen

trat

ion

(µg

m-3

)

Sampling Date

Episode 1 Episode 2

05

101520 Theodore Roosevelt North Unit (THRO-N)

Nitrite Chloride Sodium Potassium Magnesium Calcium Ammonium Nitrate Sulfate

05

101520 Fort Union (FOUN)

Does ammonia limit NH4NO3 formation in Bakken?

0

0.2

0.4

0.6

0.8

1

NH

3 / (N

H4+ +

NH

3) FOUS THRO-N

• Ammonia nearly depleted in Theodore Roosevelt National Park during episode 1, but not episode 2.

• Excess ammonia always available at Fort Union.

• HNO3 currently limits NH4NO3 formation

1 2

HOW CAN WE ROUTINELY MEASURE NH3 AND NH4

+ ?

U.S. network measurements of inorganic N species concentrations

• NO3-

– CASTNet quantifies PM2.5 deposition – PM2.5 concentrations also measured by IMPROVE and CSN

• HNO3 – CASTNet quantifies weekly concentration/deposition

• NH4+

– CASTNet quantifies weekly concentration/deposition • NH3

– AMoN (bi-weekly) – Regional networks (e.g., SEARCH) – Short-term/special studies

Radiello passive NH3 samplers

• Inexpensive • Greater spatial

coverage • ~1-2 week time

resolution • Excellent precision

and good accuracy • NH3 only

Replicate passives

Passive vs. denuder

NE Colorado spatial NH3 gradients

Li et al., in prep

NADP AMoN Network

• Growing network of passive ammonia sampling

• Ideal for NH3 deposition Figure courtesy of Chris Lehmann

Limitations to AMoN passive sampling approach

• Low time resolution (1-2 weeks is typical) makes source attribution difficult

• Does not measure NH4

+

– Leaves total NHx burden unconstrained – Limits ability to understand PM formation – Limits ability to validate model simulations

Pilot IMPROVE NHx network

• Rocky Mountain focus • 9 sites, 1-in-3

day sampling • 4/2011 - 8/2012

• Single phosphorous acid-coated filter to capture NH4

+ + NH3

• Good accuracy vs. reference URG denuder/filter-pack (denuder + filter + backup denuder)

• Excellent field precision demonstrated by co-located samplers

NHx measurement quality

• Highest concentrations at eastern and southern sites

• Seasonal cycle apparent at all sites

• Fall/winter secondary max in ag regions

• Fire influence at Chiricahua in 2011

Chen et al., 2014

IMPROVE NHx data overview

Total N deposition budgets: wet + dry

Li et al., in prep

Anticipated future emissions changes will make NHx increasingly even more important

Ellis et al., 2012

NOx expected to decrease while NH3 increases

Summary • Ammonia is an important contributor to dry & wet deposition of reactive N

• As NOx emissions decrease, NHx is an increasingly important component of N deposition

• Ammonia also a key factor affecting PM acidity and NH4NO3 formation – Abundant ammonia supports greater

NH4NO3 PM formation and haze

• Network measurements needed to routinely characterize NH3 and NH4

+ at higher time resolution to – Understand PM formation – Validate air quality models – Attribute source contributions

Increase in NH4+ fraction

• A sizable increase in the NH4+ fraction (absolute % change) of wet inorganic

nitrogen deposition is seen across most of the country (2010 – 1989)