Enhanced Delaware Air Toxics Assessment StudyProject Partners

University of Delaware Murray Johnston PhD

Duke UniversityAndrey Khylstov PhD

EPA Region IIINational Exposure Research Laboratory

Enhanced Delaware Air Toxics Assessment StudyGoals

To better understand, the micro-level air quality impacts of emission sources.

To enhance the spatial resolution of the ambient toxics dataset by incorporating mobile measurements into the program.

To define chromium measurements as CrIII and CrVI.

The study was initiated in 2005 by DNREC.

Add Aerosol and Mobile measurements to enhance temporal and spatial resolution of toxics monitoring network.

Major components – Toxics Monitoring, Emissions inventory, Modeling (local and regional), Risk Assessment, Aerosol Characterization, and Mobile measurements.

Enhanced Delaware Air Toxics Assessment Study Historical Development

Enhanced Delaware Air Toxics Assessment StudyClasses of Air Toxics Monitored

(Traditional Network)

Volatile Organic Compounds (VOC)

Carbonyls

Metals

Enhanced Delaware Air Toxics Assessment Study

Location of Location of Monitoring StationsMonitoring Stations

• Martin Luther King Blvd.area (Urban)

• Lums Pond State Park and Summit Bridge area (Suburban/Rural)

• Delaware City area (Industrial)

• Felton / Killens Pond State Park area (Rural)

• Seaford area (Suburban/Urban)

Monitoring locations established throughout state to provide real data. Data collected approximately every 6 days.

Area of Martin Luther King Monitoring Station

Martin Luther King Monitoring Station

Enhanced Delaware Air Toxics Assessment StudyPartners

Real-Time, Single Particle Mass Spectrometry - Murray Johnston, PhD, Department of Chemistry and Biochemistry University of Delaware.

Mobile Measurements for Formaldehyde and Chromium III, VI – Andrey Khylstov, PhD, Duke University.

193 nmArF laser

Focusing Lens

Flight Tube LinerPost Acceleration Ion

Detector

Rotary Valve

Flow LimitingOrifices

Ionization/ Ion Extraction Region

Pumping Stages

hνPositive Ion PathNegative Ion PathParticle Flow

Nafion Particle Dryer

OutsideAirPositive IonsNegative Ions

Ion SignalOut

Aerodynamic Sizing Inlet

Real-Time Single Particle Mass Spectrometer V.3 (RSMS-3)

M.P. Tolocka, D.A. Lake, M.V. Johnston, A.S. Wexler, “Size-Resolved Fine and UltrafineParticle Composition in Baltimore, Maryland”, Journal of Geophysical Research, Atmospheres (2005) 110, D07S04, doi:10.1029/2004JD004573.

K.J. Bein, Y. Zhao, A.S. Wexler, M.V. Johnston, “Speciation of Size-Resolved Individual Ultrafine Particles in Pittsburgh, Pennsylvania”, Journal of Geophysical Research, Atmospheres (2005) 110, D07S05, doi:10.1029/2004JD004708.

Real-Time Single Particle Mass Spectrometer Sampling Protocol

Sampling interval – 1 hour

Each sampling interval consists of:• 5 successive particle size bins (770, 440, 220, 110, 50 nm)• Acquire single particle spectra for 40 min (5-10 min per bin)

Analysis modes:•Ambient aerosol sampled directly into RSMS-3; operate instrument up to 24 hr. per day (1000-2000 particles/day)

•Ambient aerosol sent into a particle concentrator; concentrator output sampled into RSMS-3; operate ca. 7 hr. per day (up to 10,000 particles/day)

Concurrent particle size distribution measurements with a scanning mobility particle sizer (SMPS; TSI, Inc.)

Real-Time Single Particle Mass Spectrometer Urban Aerosol Measurements with RSMS-3

107,000(through 8/05)

Apr 2005 - Jan 2006Wilmington

365,000Mar 2002 - Dec 2002Baltimore

236,000Aug 2001 - Aug 2002Pittsburgh

23,000Aug-Sept 2000Houston

18,000Aug 1999Atlanta

Particles AnalyzedDatesLocation

Real-Time Single Particle Mass SpectrometerMass Spectra of a Single 50 nm Diameter Particle

Baltimore, MD (17:20 EST, 7/20/02)

m/z200150100500

Na+

K+

K2O+Pb+

m/z200150100500

Na+

K+

K2O+Pb+

m/z200150100500

O-

SO-

SO2-

orS2

-SO3

-SO4

-

m/z200150100500

O-

SO-

SO2-

orS2

-SO3

-SO4

-

200150100500

O-

SO-

SO2-

orS2

-SO3

-SO4

-

PositiveIons

NegativeIons

Real-Time Single Particle Mass Spectrometer Summary of Single Particle Measurements in

Wilmington, Delaware (April-August 2005)

82,401July 13 – Aug 25

20,479May 4 - June 3

4,941April 3-22

Particle HitsTime Period

0

1000

2000

3000

4000

5000

60000

30

60

90

120

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0

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All Data

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All Particles

Particle Hits vs. Wind DirectionMay-June July-Aug

Mobile Sampling

Objective:

To provide information on the spatial distribution of pollutants throughout the city as well as variability within neighborhoods with the spatial scale of the order of 100 meters.

Methodology:

Mobile measurements of:• PM water-soluble chromium species, • gas-phase formaldehyde, and • aerosol number size distribution • ozone (possible)Time resolution: 10 – 40 secSpatial resolution: ~ 100 m

Reagent for Cr(VI)

Steam Jet AerosolCollector (SJAC)

Liquid

Sample

Oxidant for Cr(III)

Syringepump

SyringepumpReagent for Cr(III)

Reactor*

Reactor*

Waste

Waste

Lamp

Spectrometer

Spectrometer

PC

Ambient air Sample(16.7LPM)

Absorbance@ 546nm

PeristalticPump

Absorbance@ 546nm

• Liquid sample containing collected aerosols is used for Cr(VI) and Cr(III) analysis.• Cr(VI) is analyzed using the diphenycarbazide colorimetric method. Absorbance at 546nm is used for concentration determination.• The analytical method for Cr(III) is similar to that of Cr (VI), except that Cr (III) needs to be oxidized to Cr(VI) before analysis.• *Teflon AF-2400 tubing Liquid core waveguide is used inside the reactor for lower detection limit.

Mobile Sampling (Chromium III, VI)

SpectrometerPC

Sampling Air

To Pump

Liquid sample

Peristaltic Pump

Reagent

Heated Reactor

Temperature Controller

UV LED

• Ambient HCHO is collected by the wet denuder with collection efficiency ~70%.

• Collected HCHO liquid sample is analyzed with fluorometric method with UV LED emission at 375nm, and excitation measured at 465nm.

Wet Denuder

Mobile Sampling (Formaldehyde)

• Time resolution for Cr (VI), Cr(III) and HCHO– As low as 1 second– Normally run at several

seconds for lower noise level

• Limit of Detection of Cr (VI)– 0.190 ng/m3 Cr(VI)

• Limit of Detection of Cr (III)– 1.935 ng/m3 Cr(III)

• Limit of Detection of HCHO– 0.026 umol/m3

Air sample line

Steam Jet Aerosol Collector

Syringe Pump

PeristalticPump

Reactors for Cr(VI) &Cr(III)

Lamp

SpectrometersReactor for HCHO

Temp.Controller

Mobile Sampling

Mobile SamplingScanning Mobility Particle Sizer (SMPS)

Measures :• Number size distribution• Volume size distribution• Number concentration• Volume concentration below 350 nmSize range: 12 nm – 350 nmTime resolution: 40 s

Volume of particles smaller than 0.3 μm is proxy for traffic-related PM2.5

Condensation Particle

Counter (CPC)

Differential MobilityAnalyzer (DMA)

Sheath Flow

AerosolIn Neutralizer

Size Distribution – Pittsburgh July 2001

101 102 103

Size Distribution – Pittsburgh July 2001

101 102 103

Number Distribution Volume Distribution

SMPS

Diameter (nm)

Customer FocusExample of Aliphatic Amine Particle Classes:

12% by Number (PM 0.5) during May-June 2005

0

0.05

0.1

0.15

0.2

0.25

0 25 50 75 100 125 150 175 200 225 250

C+

NH+NH4+

NO+CH4N+CH2O+

C3+C3H3+, C2HN+

CNO+, C2H6N+

C5H11N+C2H7NO+

0

0.05

0.1

0.15

0.2

0.25

0 25 50 75 100 125 150 175 200 225 250

C+

NH+NH4+

NO+CH4N+CH2O+

C3+C3H3+, C2HN+

CNO+, C2H6N+

C5H11N+C2H7NO+

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 25 50 75 100 125 150 175 200 225 250

C+NH+

NH4+

C3+C3H3+, C2HN+

CNO+, C2H6N+

C3H8N+C2H4NO+

NO+CH4N+CH2O+

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 25 50 75 100 125 150 175 200 225 250

C+NH+

NH4+

C3+C3H3+, C2HN+

CNO+, C2H6N+

C3H8N+C2H4NO+

NO+CH4N+CH2O+

0

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m/z85 ALL

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50

100

150

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All m/z 58

0

500

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20000

30

60

90

120

150

180

210

240

270

300

330

0

500

1000

1500

2000

All Particles

Few amine particles from the north and west relative to the

total particle hits

Customer FocusEmission Profile of a Diesel Locomotive using SMPS

Two Amtrak Diesel Engines Attached to One Another (No Freight Cars) Passing the MLK Site at 12:14 PM EST (6/08/05)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

5.18e+002

Impactor D50

10 100 1000

21.7

Con

c. (

dN #

/cm

³)[e

3]

Diameter (nm)

12:13 PM EST

Wind Direction = 208° at 3.6mph

0.0

0.5

1.0

1.5

2.0

2.5

3.0 2.61e+004Impactor D50

10 100 1000

21.7

Con

c. (

dN #

/cm

³)[e

3]

Diameter (nm)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

2.61e+004

Impactor D50

10 100 1000

21.7

Conc

. (dN

#/cm

³)[e4

]

Diameter (nm)

12:14 PM EST

Wind Direction = 250° at 4.5mph

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1.70e+003

Impactor D50

10 100 1000

21.7

Con

c. (

dN #

/cm

³)[e

3]

Diameter (nm)

12:15 PM EST

Wind Direction = 260° at 1.9mph

0.0

0.5

1.0

1.5

2.0

2.5

3.0

7.03e+002

Impactor D50

10 100 1000

21.7

Con

c. (

dN #

/cm

³)[e

3]

Diameter (nm)

12:16 PM EST

Wind Direction = 96° at 0.9mph

Customer FocusAnalyzing Sub-Grid Variability

Typically, photochemical models provide results at a coarse grid resolution For every grid resolution, there are sub-grid features:

CMAQ 4x4 km grid

Local details within a grid cell

SGV distribution

Customer FocusAnalyzing Sub-Grid Variability

Detailed fine-scale measurements are needed for model evaluation

Customer Focus Analyzing Sub-Grid Variability

Using Fine-Scale Mobile Measurements to Analyze SGVLocations of mobile measurements in Wilmington, DE

4 km x 4 kmarea

represents one CMAQ

grid cell

Examples:3-hour average concentrations of CrVI and fine particulates from mobile measurements in Wilmington, DE

Conclusions

Real-Time Mass Spectrometry will enable DNREC to better define potential source impacts at the MLK site. This information will be helpful in defining control strategies.

Mobile Monitoring will help with the evaluation of the modeling exercises that are being performed as part of this toxics project.

A lot still needs to be done.

Progress Report

Spring and Summer Sampling intensives are complete.

Need to complete the Fall and Winter intensives.

Data analysis to meet project objectives.

Questions