continuous ammonia monitoring - us epa · – marga – steam jet collection – ic • potential...

Continuous Ammonia MonitoringJim Schwab, ASRC, University at Albany, SUNYWith contributions from Eric Edgerton, ARA, Cary, NC

Additional Contributers

• Minsuk Bae, Yongquan Li, Ken Demerjian, John Spicer – ASRC

• Sara Pryor – Indiana University• Bjarne Jensen - Danish National

Environmental Research Institute • Jian Hou, Xianliang Zhou –

University at Albany School of Public Health

• Donna Kenski - LADCO

Measurement Challenges

• Low concentrations – generally near or less than 1 ppbv, except near sources

• Highly reactive – sticks to surfaces, especially those that are “wetted” or covered with water molecules

• Oxidized nitrogen species (NO, NO2, HNO3, etc.) are generally much more abundant – it can be difficult to “see” the reduced nitrogen species against this background.

Integrated Methods• Passive Samplers

– Tube– Badge

• Active Samplers– Denuders

• Annular• Honeycomb• Tubular

– Filter Packs (ACID-MODES)– Fabric Mesh Filters (Dennis Fitz, UCR)

Source: Eric Edgerton

Mean NH3 at SEARCH Sites (ppb)CY 2004 – Annular Denuder Method

Rural

Suburban

Urban

2.44

0.22

1.84

1.24

0.42

0.75

0.24

0.56

Yorkville

Continuous Methods• Research Methods

– Tunable Diode Laser – TDLAS– Wet Effusive Diffusion Denuder (WEDD)– Wet Scrubbing Long Path Absorption Spectrometer –

WS-LOPAP– Wet Scrubbing IC analysis (URG AIM 9000, Dionex

GP-IC?)– MARGA – Steam Jet Collection – IC

• Potential Routine Methods– Ion Mobility Spectrometer– Laser Acousto-Optical Detection– Chemiluminescence

• SEARCH TRN• API Model 201E or Thermo Model 17C (1 ppb LDL)

– AiRRmonia – ECN, Netherlands, MechatronicsInstruments, b.v.

SEARCH Continuous NH3Method (TRN)• 2-channel oxidized AND reduced nitrogen

chemiluminescence analyzer• Channel 1 samples ambient air through a

sodium carbonate denuder (TN), then two heated converters

• Channel 2 samples ambient air through dual sodium carbonate and citric acid denuders (TN* ), then through a single moly converter

• NH3 operationally defined as TN-TN*

Total Reduced Nitrogen (TRN) Analyzer

650º C Pt Converter

350º C MolyConverters

Total Reactive Nitrogen after Na2CO3 denuder

Total Oxidized Nitrogen after Na2CO3 and citric acid denuders

0

15

30

45

60

75

5/4/05 0:00 5/4/05 3:00 5/4/05 6:00 5/4/05 9:00 5/4/05 12:00 5/4/05 15:00 5/4/05 18:00 5/4/05 21:00

SO2

(ppb

)

0

1

2

3

4

5

6

7

8

9

10

NH

3, N

H4,

NH

x (p

pb)

SO2 NH4 NH3 NHx

NH3 and NH4+ during CFPP Plume Event

NH4+ increases; NH3 disappears; NHx conserved

1-minute NH3 and WD at Yorkville

0

5

10

15

20

8/28/06 0:00 8/28/06 6:00 8/28/06 12:00 8/28/06 18:00

NH

3 (p

pb)

0

45

90

135

180

225

270

315

360

WD

(deg

.)

NH3 WD

Spikes between 90 and 180 degrees suggest nearbyNH3 sources.

Local Sources of NH3 at YRK

Poultry operationswithin several km line up with NH3spikes.

2.6 km

1.5 km

3.3 km

Method 2 - IMS• Candidate for routine monitoring• IMS – Ion Mobility Spectrometer (AirSentry-IMS

Ammonia Analyzer, Particle Measuring Systems, Boulder, CO)

• Ionization based time-of-flight technique performed at atmospheric pressure

• Instruments are targeted to a specific molecule in a specific concentration range

• Range for this instrument: 0–300 ppb (Lab Intercomparison); 0-100 ppb (Field Deployment)

• Cost (with OBC) ~ $26 K

Operational Details

• Requires up to 5 li/min of clean, dry instrument air (dewpoint ≤ -40º C)

• Internal sample pump option• Factory default “Smoothing Factor” (8)

should be increased for minute (or longer) averaged data

• Optional “On Board Calibration” - integral permeation oven set up (recommended)

• Nickel 63 sealed radioactive source (less than .005 microcuries) – ionization source

NH3 - PSP - Addison, NY; May 7-13, 2006

0

0.20.4

0.6

0.8

11.2

1.4

1.6

5/7/20060:00

5/7/200612:00

5/8/20060:00

5/8/200612:00

5/9/20060:00

5/9/200612:00

5/10/20060:00

5/10/200612:00

5/11/20060:00

5/11/200612:00

5/12/20060:00

5/12/200612:00

5/13/20060:00

5/13/200612:00

5/14/20060:00

NH

3 (p

pb)

NH3 - PSP - Addison, NY; M arch 5-11, 2006

-1

0

1

2

3

4

5

6

7

3/5/20060:00

3/5/200612:00

3/6/20060:00

3/6/200612:00

3/7/20060:00

3/7/200612:00

3/8/20060:00

3/8/200612:00

3/9/20060:00

3/9/200612:00

3/10/20060:00

3/10/200612:00

3/11/20060:00

3/11/200612:00

3/12/20060:00

NH

3 (p

pb)

Preliminary data: do not cite or quote!

IMS Field Data

Laboratory Intercomparison

• September 12-30, 2005 at ASRC• Six measurement Methods – seven

instruments in all (Chemiluminescence method not included in analysis due to “conversion problem”)

• Heated glass manifold for uniformity of sampling environment

• Synthetic air and calibration system• “Ambient” sample for two extended periods

Pranalytica Nitrolux NH3 Analyzer

Photoacoustic spectroscopyCO2 laserLow-noise microphoneIn-line particle filter (40 µm)LDL and cost depend on model

Model 1000 – LDL ~ 1 ppb; Cost ~$24KModel 200 – LDL ~ 0.2 ppb; Cost ~$38KModel 100 – LDL ~ 0.1 ppb; Cost ~$72K

Note: Instrument used was one of the first sold by Pranalyticaand company claims to have made significant improvements to later (i.e. current) instruments

Method Characteristics Tested during Intercomparison• Response to known [NH3] –

accuracy and precision of calibration• Time Response – to step changes

and “spikes”• Comparability during ambient

sampling• Potential interferences

9/28: Zero, 5, 10, 20 ppb

0

5

10

15

20

25

6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

[NH

3] -

ppb

IMS Nitrolux TDL LOPAP WEDD1 WEDD2

Preliminary data: do not cite or quote!

9/26: 40 ppb spike from zero

0

5

10

15

20

25

30

35

40

10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00

[NH

3] -

ppb

IMS Nitrolux TDL LOPAP WEDD1 WEDD2

Preliminary data: do not cite or quote!

9/24: Ambient Spike

0

2

4

6

8

10

12

14

16

18

9/24/200518:00

9/24/200519:00

9/24/200520:00

9/24/200521:00

9/24/200522:00

9/24/200523:00

9/25/20050:00

9/25/20051:00

9/25/20052:00

9/25/20053:00

[NH

3] -

ppb

IMS Nitrolux TDL LOPAP WEDD1

Preliminary data: do not cite or quote!

Sampling and response time• This is an important issue for

gaseous ammonia measurement – it clearly affects methods detecting gaseous ammonia directly and ammonium after scrubbing.

• The TDL is the system of choice for quick and accurate response – but it is not a “routine” method!

Best Candidate Methods for Monitoring – and their Major Shortcoming(s)

(Editorial Opinions!)• ARA TRN (chemiluminescence)

– Not ammonia specific– Three heated converters – difference– Custom implementation of proven analyzer– Response time?

• AirSentry IMS (Particle Measuring)– Response Time

• Nitrolux 200 (or 100) (Pranalytica)– Response Time (worst of all tested

instruments, but should be better in current versions)

– Cost – Highest of “routine monitoring”candidates (for sufficiently low LDL)

Acknowledgements

• Funding from – EPA– NYSERDA– NYSDEC

• Although the research described in this article has been funded in part by the U.S. Environmental Protection Agency, it has not been subjected to the Agency’s required peer and policy review and therefore does not necessary reflect the views of the Agency and no official endorsement should be inferred should be inferred.