enhanced delaware air toxics assessment study project ......real-time single particle mass...
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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
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60000
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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
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0.35
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0 25 50 75 100 125 150 175 200 225 250
C+NH+
NH4+
C3+C3H3+, C2HN+
CNO+, C2H6N+
C3H8N+C2H4NO+
NO+CH4N+CH2O+
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m/z85 ALL
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All m/z 58
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500
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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