Advanced Sampling and Data Analysis for Source Attribution of Ambient Particulate Arsenic and Other Air Toxics Metals in St. Louis

Missouri Department of Natural Resources, Air Pollution Control Program and Environmental Services Program

Washington University, St. Louis

U. S. EPA

Introduction

● The St. Louis Community Air Project (CAP) and the Blair St. National Air Toxics Trends Station (NATTS) have collected ambient air quality data that showed elevated concentrations of arsenic (among other hazardous air pollutants) were present in the ambient air in St. Louis. Accompanying these elevated ambient arsenic concentrations was an excess risk of cancer due to a lifetime inhalation exposure to ambient arsenic.

● This Community-Scale Air Toxics Monitoring Project will attempt to identify and locate possible sources of arsenic emissions in the greater St. Louis area.

● The first task of this project was to analyze quality-assured ambient arsenic data and an arsenic emissions inventory for the greater St. Louis area.

Summary of CAP and NATTS Monitoring Results

CAP: average arsenic concentration ~ MDL ~ 1/100,000 cancer benchmark = 0.002 ug/m3

Blair St. and Arnold PM2.5 STN arsenic average about 0.002 ug/m3, Bonne Terre about 0.001 ug/m3

NATTS: average arsenic concentrations ~ 0.002 to 0.001 ug/m3 at Blair St.; MDL ~ 0.00002 ug/m3 = 0.02 ng/m3

Blair St. NATTSAnnual Average PM10 Arsenic Concentration

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

2005 2006 2007 (Jan-Jun only)

ug

/m3

Arsenic 1E-06 Risk-Based Concentration

Excess Cancer Risk Characterization for Arsenic (PM10 and PM2.5) Based on Blair St.

Ambient Monitoring Data

Size Category Year

Annual

Arithmetic Mean

(μg/m3)

Risk-Based Concentration

(Risk = 1E-06, 70-Year)

(μg/m3)

Excess

Cancer Risk (1E-06)

PM10 (NATTS, analyzed by ICPMS)

2004 0.001660 2E-04 8

2005 0.002330 2E-04 12

2006 0.001060 2E-04 5

2007 0.001120 2E-04 6

PM2.5 (STN, analyzed by XRF)

2004 0.0029 2E-04 15

2005 0.0026 2E-04 13

2006 0.0017 2E-04 9

2007 0.0015 2E-04 8

Arsenic Emission Inventory for the Greater St. Louis Area

● Staff received the 2002 National Emissions Inventory (NEI) stack-level emissions data for sources of arsenic compounds (inorganic, including arsine) for the seven surrounding counties and St. Louis City from U.S. EPA Region 7 staff. Staff obtained the 1999 NEI from the 1999 National-Scale Air Toxics Assessment.

● Staff queried the 1999 and 2002 NEI to identify and locate tentative sources of arsenic emissions in St. Louis City and,● Jefferson, St. Charles, and St. Louis Counties, MO● Madison, Monroe, Randolph, and St. Clair Counties, IL.

1st Quarter 01-05

2nd Quarter 01-05

3rd Quarter 01-05

4th Quarter 01-05

Quarterly Wind Directions, St. Louis

Arsenic High Days, Blair St. (ug/m3) WD WSDate PM2.5 PM10 (deg) (mph)

4/24/2003 0.03450 112 64/27/2003 0.01374 131 39/9/2003 0.00841 84 2

9/18/2003 0.01487 0.01574 140 29/21/2003 0.00874 140 310/9/2003 0.01227 98 14/30/2004 0.01097 177 17/5/2004 0.00937 175 27/8/2004 0.00945 149 3

7/29/2004 0.00974 145 29/3/2004 0.01590 136 2

9/21/2004 0.01519 153 29/30/2004 0.01307 153 23/29/2005 0.01108 0.00995 150 64/16/2005 0.01156 0.00865 147 26/9/2005 0.01491 0.01491 187 28/2/2005 0.01179 0.01060 150 3

8/14/2005 0.01040 1 19/4/2005 0.00853 125 2

12/21/2005 0.01063 259 21/26/2006 0.00875 150 311/4/2006 0.01209 158 4

Blair St., Frequency of Direction on High Arsenic Days

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Conditional probability function (CPF) plots for PM2.5 arsenic at the St. Louis – Midwest Supersite and PM10 arsenic at the Blair St. NATTS site. CPF plots constructed using top 25% of 24-hour integrated arsenic and hourly-average winds measured at East St. Louis. STL-SS and Blair data for the periods 6/01-5/03 and 7/02-12/06, respectively.

As High Days, Arnold (ug/m3) WD WSDate Arnold PM2.5 (deg) (mph)

5/28/2001 0.01096 54 1.56/9/2001 0.00986 93 0.1

10/28/2001 0.00977 172 2.47/4/2002 0.01595 313 0.2

4/27/2003 0.00840 159 1.06/17/2003 0.00919 7 0.68/22/2004 0.00925 180 0.84/19/2005 0.00819 188 3.96/30/2005 0.01557 248 1.2

Arnold, Frequency of Direction on High Arsenic Days

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Grant School, Frequency of Direction on High Arsenic Days

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As High Days, Grant (ug/m3) WD WSDate Grant PM2.5 (deg) (mph)

8/29/2001 0.00536 112 2.911/9/2001 0.00688 246 2.411/21/2001 0.00956 188 4.42/19/2002 0.01471 172 7.43/18/2002 0.00524 99 3.25/5/2002 0.00512 173 5.3

Considerations

● Ambient monitoring at the Blair St. NATTS reveal that the ambient PM10 and PM2.5 arsenic concentrations dropped in St. Louis City between 2004 and the first half of 2007. Future measurement and data analysis will determine whether this trend will continue for the long term.

● Despite this downward trend, these ambient PM10 and PM2.5 arsenic concentrations are still associated with a cancer risk greater than 1− in −1,000,000 based on a 70-year exposure.

Considerations

● According to the 1999 and 2002 NEIs, the majority of the point sources of arsenic compounds and associated facilities were located on the eastern side of the Mississippi River in the Illinois counties of Madison and St. Clair.

● The largest amount of arsenic compounds released to the ambient air, however, occurred on the western side of the Mississippi River in the Missouri counties of Jefferson and St. Charles.

Project Goals

● This community-scale air toxics monitoring project may help to identify the general area where sources of arsenic compounds are located, if not the sources themselves, the climatology involved, and other aspects of the ambient data.

● This project may also provide information on whether the existing emission inventories are providing adequate information on the magnitude of these emissions.

● The project will also provide results for other toxic metals, including lead, which may be of interest in determining whether urban concentrations are near levels of concern, and where source areas may be.

Project Plan

• Phase I. Spatially and Temporally Enhanced 24-hour Integrated Measurements: 1-in-3 day PM10 sampling and metals analysis at 4 sites in the St. Louis area for 1 year (MDL~0.02-0.03 ng/m3, 24-hr samples)

• Phase II. High Time Resolution Measurements: Time-resolved near-real-time analysis at six sites in the St. Louis area for 1 month at each site (MDL<0.1 ng/m3, possibly as low as 0.01 ng/m3, 4-hr samples)

• Data Analysis and Reporting: source apportionment, source identification, model comparisons – MDNR and Washington University

Project Timeline

Work Plan Task Performance Period (Project Quarter): Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8Section Calendar Quarter (assuming 10/1/07 Start): 07Q4 08Q1 08Q2 08Q3 08Q4 09Q1 09Q2 09Q33a 1. Monitor siting3b 2. Phase I QAPP Q1|

3. Integrated sampling and analysis-- - ICP-MS method optimization3c - Routine sampling and ICP-MS analysis3c - Data uploaded to AQS Q2| Q3| Q4| Q5|

4. Sampler construction and testing3d - Bid offer and selection3d - Sampler construction and testing3e 5. Phase II QAPP Q3|

6. High time resolution sampling and analysis 3f - Routine monitoring (6 mo. over a 9 mo. period)3g 7. Data analysis3h 8. Final Project Report preparation

Hall St.

Blair St.

Washington University

Arnold

(Phase I)

Blair Street

Hall Street

Washington University

Arnold West

Cooper Environmental ServicesXact 620 Ambient Air Toxic Metals Monitor

PM size-selective inlet

Temperature controlled 19 inch rack

Heater

Sampling & Analysis Module

Operator interface/control panel

Flow control module

This and the following slide provided by John Cooper, Cooper Environmental Services

XACT SAMPLING AND ANALYSIS

X-Ray TubeX-Ray Tube

Filter TapeFilter Tape

Aerosol DepositAerosol Deposit

Chemistry ZoneChemistry Zone

Sample FlowSample Flow

Analysis AreaAnalysis Area

Filter TapeFilter Tape

Previous sample is analyzed while current sample is collected

Phase I Analytes• Arsenic• Cadmium• Chromium• Lead• Manganese• Nickel

Potential Xact AnalytesMeasured by XRF

Potential Phase II Locations

• Blair Street• Arnold West?• Chain of Rocks??• Illinois???• Others?

Hall St.

Blair St.

Washington University

Arnold

(Phase I)

(Phase II)

?