Ammonia: Measurement role in National Ambient Air

NetworksRich Scheffe

Office of Air Quality Planning and Standards, U.S. EPA

Acknowledgements

• Brian Timin, EPA• Spyros Pandis, CMU• Jay Turner, Washington University• Eric Edgerton, ARA• Jim Homolya, EPA

Topics• Role of NH3 in air quality management• Overview of NH3/related measurements in

routine networks• Measurement issues• National Monitoring Strategy and

associated recommendations

NH3…effects

• Deposition– watershed eutrophication– Acidification/neutralization

• Global climate radiation budget (aerosol)• National Air program standards

– PM10

– PM2.5

Regulatory Timetables

Phase IIAcid Rain

Compliance

MercuryDetermination

ProposedUtilityMACT

New Fine PM NAAQSImplementation Plans

Designate Areasfor Fine PM NAAQS

Ozone

Acid Rain, PM2.5, Haze, Toxics

1-hr Severe Area

Attainment Date

Compliance for BART Sources

NSR Permits for new sources & modifications that increase emissions

99 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17

OTC NOx

Trading

1-hr Serious Area Attainment

Date

NOx

SIPs Due

Designate areas for8-hr Ozone NAAQS

NOx

SIP CallRed-uc-tions

00 18

FinalUtilityMACT

Compliancewith Utility MACT

Assess Effectiveness of Regional Ozone Strategies

Regional Haze SIPs due

Latest attainmentdate for Fine PM

NAAQS 3

Compliance for BART sources under the Trading Program

Second Regional Haze SIPs due

Marg-inal 8-hr Ozone

NAAQS Attain-ment Date Possible

Regional NOx

Reductions ?(SIP call II)1

Interstate Transport Rule to Address SO2/ NOx Emissions for Fine PM NAAQS and Regional Haze

Note: Dotted lines indicate a range of possible dates.

1 Further action on ozone would be considered based on the 2007 assessment.2 The SIP-submittal and attainment dates are keyed off the date of designation; for example, if PM or ozone are designated in 2004, the first attainment date is 2009

EPA is required to update the new source performance standards (NSPS) for boilers and turbines every 8 years

Serious 8-hr Ozone NAAQS attainment

Date

Moderate 8-hr Ozone NAAQS AttainmentDate

8-hrOzone Attain-mentDemon-stration SIPs due

In developing the timeline of current CAA requirements, it was necessary for EPA to make assumptions about rulemakings that have not been completed or, in some case, not even started. EPA’s rulemakings will be conducted through the usual notice-and-comment process, and the conclusions may vary from these assumptions.

Further progress under the Clean Air Act is complex, burdensome and uncertain

Complex system

• Measurements– Stability/volatility

• Ammonium nitrate, association with nitric acid (sticky)– Real exposure indoors?...given volatility?

• Consequently, NH4, NH3g, HNO3g all present challenges

• Uncertain emission estimates– Diversity of area sources– Many agricultural based

• Modeling confounded by heterogeneous processes and above (i.e., ability to diagnose)

NH3 is not a “central” player in atmospheric chemistry; however, various inter-pollutant interactions impact pollutant/component specific

strategies?fine particle (FP) formation.

·OH

O3

HONO

VOC

Radical PoolHO2·; RO2·

Carbonyls

NO

HNO3

FP

NO2

SOx

H2SO4

NH3

HOOH

hv

hv

CO

hv

SOx

Clouds/Aqueous

orgaer

Source

Secondary

Sink

PAN N2O5

Nighttime N2O5

·NO3

Chemistry

H O2

hv

O1

D

O3

P

hv

Figure 4. Linkage between oxidant chemistry and

NH4NO3

Organic Carbon

Ozone

Sulfate

Nitrate

Reductions of?

Impacts on major aerosol components due to precursor reductions…confusing!

???

???

???

???

VOC/COSOxNOx

Consequently,

Is NH3 limiting…..in formation of ammoniumnitrate?

• Or, where and when are are NOxcontrols most effective in reducing p-NO3?

Limiting Reactant: Ammonia or Nitric Acid(courtesy, Pandis, CMU)?

0 10 20 30 40

0

20

40

60

80

10

30

50

Ammonium Nitrate (µg m-3)

Tota

l Nitr

ic A

cid

(µg

m-3

)

Total Ammonia (µg m-3)

A

B

A:Ammonia limited

B: Nitric acid limited

The Sulfuric Acid/Ammonia System 2001…courtesy, Pandis, CMU

02468

101214161820

0 1 2 3 3.6 5 10

AmmoniaAmmoniumSulfateBisulfateSulfuric acid

Total Available Ammonia (µg m-3)

Co

nce

ntr

atio

n (µ

g m

-3)

2 Ammonia:1 Sulfate

Model Sensitivity Runs

• When/where are Nox controls most effective?

• Impact on nitrates associated with SO2 and VOC reductions

CMAQ Ammonia Sensitivity Runs-50% NH3 Reduction- January

Basecase Nitrate Nitrate with 50% Ammonia Reduction

50% NOx Reduction- JanuaryEffect on Sulfate and Nitrate

50% NOx Reduction- Reduced NH3 base (50% NH3 reduction)- January effect on Sulfate and Nitrate

50% SO2 Reduction- JulyEffect on Sulfate and Nitrate

50% SO2 Reduction- JanuaryEffect on Sulfate and Nitrate

Seasonal Average IMPROVE Nitrate

Seasonal Average Particulate Nitrate- IMPROVEand CASTNET Visibility Network*

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

Improve Observations (ug/m3)

CM

AQ

Pre

dic

tio

ns

(ug

/m3)

Summer

Fall

Spring

Winter

*CASTNET Visibility network data is for 8 sites- fall only

Where are the measurements?• Ammonium (Dry)....PM2.5 speciation (including IMPROVE);

CASTNET

• Ammonium Wet (NADP)

• NH3….SEARCH/ARIES…..network

• Special studies (PM2.5 Supersites)

Trends (54)Supplemental (~215 sites currently known)SupersitesDaily Sites IMPROVEIMPROVE Protocol Castnet conversion Deploy in 2002 Deploy in 2003

Current/Planned Urban & Rural PM2.5 Speciation Networks

SS SS

SS

01/02

SS

SS

SS

SS

SS

SEARCH Enhanced Air Quality Measurement Network

Oak Grove (OAK)

Centreville (CTR)

Pensacola (PNS)

Yorkville (YRK)

Jefferson Street (JST)

North Birmingham (BHM)

Gulfport (GFP)

Outer Landing Field #8 (OLF)

rural urban suburban

CASTNET NH4…1992 CASTNET NH4…2002

Measurement Issues, NH3

• Integrated methods– Absorption, extraction, analysis

• CASTNET filter pack/denuder system (1 week)• Acid denuders in low volume particle samplers (typically 24

hr.)– Labor intensive, lack temporal detail

• Semi-continuous methods– Cycled difference techniques– IC particle/gas methods– Optical techniques (FTIR, DOAS)– Cost, familiarity, reliability, commercial availability

Measurement Issues, NH4

• PM2.5 speciation networks– 24 hr. integrated measurement; 1/3 day– 54 trends sites; ~200 SIP sites

• Acid gas denuding; nylon (basic) filter substarte

– small subset of IMPROVE sites• Acid/base gas denuding; nylon (basic) filter substrate…traps NO3 loss…what about NH3 loss?

Recent Example Applications

• St. Louis Supersite (Integrated)• Search/ARIES…ARA (continuous)

Daily 24-Hour Integrated Ammonia: St. LouisUrban/Rural Contrast (Aug-Nov 2001)..courtesy of Jay Turner, Washington

University

0

2

4

6

8

10

12

14

08/17/01 08/27/01 09/06/01 09/16/01 09/26/01 10/06/01 10/16/01 10/26/01 11/05/01 11/15/01 11/25/01

Am

mon

ia C

once

ntra

tion

(ppb

)

Park Hills, MO (90 km south of St. Louis)

East St. Louis, IL (3km east of City of St. Louis, MO, central business district)

Lat. 33.95 NLong. 85.01 WElev. 390 m

Trace gasesMet

Particleanalyzers

Yorkville, GA SEARCH Site (courtesy, ARA..Edgerton)

Instrumentation

• 10 meter met• Trace gas: O3, CO, SO2, NO, NO2(photolytic),

HNO3, NOy• Filter PM 2.5: FRM Mass, Particle Composition

Monitor (PCM) Speciation Monitor• Filter PM Coarse Mass (Dichot)• Semi-Continuous PM: Nephelometer,

Aethelometer, R&P 5400, Harvard SO4, ARA NO3/NH4, Dried 30°C TEOM

TRN Diagram

TRN NH3 vs Denuder NH324 Hour Samples

Continuous NH3 = 1.12 Denuder NH3 - 0.19R2 = 0.92

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

Denuder NH3, ug/m3

Con

tinu

ous

NH

3, ug

/m3

HNO3, NH3, NH4NO3 events

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.09/

24/0

3 0:

00

9/24

/03

6:00

9/24

/03

12:0

0

9/24

/03

18:0

0

9/25

/03

0:00

9/25

/03

6:00

9/25

/03

12:0

0

9/25

/03

18:0

0

9/26

/03

0:00

9/26

/03

6:00

9/26

/03

12:0

0

9/26

/03

18:0

0

9/27

/03

0:00

9/27

/03

6:00

9/27

/03

12:0

0

9/27

/03

18:0

0

[HN

O3]

ppb

v [N

O3]

ug/

m3,

[NH

4] u

g/m

3

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

[NH

3], p

pbv

HNO3 NH4 NO3 NH3

NOy Budget Time-Series

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

9/12/0

39/1

3/03

9/14/0

39/1

5/03

9/16/0

39/1

7/03

9/18/0

39/1

9/03

9/20/0

39/2

1/03

9/22/0

39/2

3/03

9/24/0

39/2

5/03

9/26/0

39/2

7/03

9/28/0

39/2

9/03

9/30/0

3

[NO

], [N

O2]

, [H

NO

3], [

NO

y], p

pbv

NO NO2 NOy HNO3

What should we do?• New National Monitoring Strategy• NCORE multiple pollutant stations• Emphasis on more science based

measurements, model evaluation, long term program accountability

National Core Network: NCORE• Goal: Move from loosely tied single-pollutant networks to

coordinated, highly leveraged multi-pollutant networks with real time reporting capability

PAMSPM

O3

O3

PM

PM

SO2

Toxics

PM

CO

IMPROVECASTNET

Level 2: ~ 75 Multi-pollutant (MP)

Sites,“Core Species” Plus Leveraging From

PAMS, Speciation Program,

Air Toxics

Level 1. 3-10 Master Sites Comprehensive

Measurements, Advance Methods

Serving Science and Technology Transfer

Needs

Level 3: Single Pollutant Sites (e.g.> 500 sites each for O3 and

PM2.5 Mapping Support

L2

Level 3

L1

NCore Measurements

Minimum “Core” Level 2 MeasurementsContinuous N,SO2,CO, PM2.5, PM10, O3; PM2.5 FRM, Meteorology (T,RH,WS,WD)…NH3, HNO3 at subset?