National Air Monitoring Conference

November 8, 2006

Las Vegas, Nevada

Matthew S. Landis

U.S. EPA Office of Research and Development, RTP, NC

Methods for Ambient Speciated

Mercury Monitoring

Acknowledgements

Frank Schaedlich & Dan SchneebergerTekran, Inc.

Robert Stevens & Tom AtkesonFlorida Department of Environmental Protection

Eric PrestboFrontier Geosciences, Inc.

Ambient Measurements to Support

Atmospheric Mercury Research

�Elucidate Atmospheric Chemistry

�Quantify Impacts from Specific Sources

�Evaluate Deterministic Models

�Provide Emission Reduction Accountability

�Species have Different Behaviors

– Elemental Mercury: Hg0

– Reactive Mercury: Hg2+

– Particulate Mercury: Hg(p)

�Atmospheric Transport & Deposition Modeling

�Bioaccumulation, Exposure & Risk Assessment

Why Speciate Mercury?

Hg0

Hg(II)

Contemporary Atmospheric Mercury

Conceptual Model

Global - Regional - Local

Hg(p)

Source: UNEP Global Mercury Assessment, 2002, using J. Pacyna 1995 data, as presented by AMAP (1998)

Spatial Distribution of Global

Atmospheric Mercury Emissions

Source: EPA estimates derived from UNEP Global Mercury Assessment, UNEP, Geneva, December 2002

• Coal and fuel combustion

is by far the largest source

category

• Estimates are rough; most

countries do not have Hg

inventories

• We need to further develop

reliable emissions

inventories

Anthropogenic Air Emissions of Mercury:

Distribution by Industrial Sector in 1995

Total: 2,382 metric tons: 2,382 metric tons: 2,382 metric tons: 2,382 metric tons

Coal/Fuel

combustion

1470 (62%)

Non-ferrous metal production170 (7%)Pig iron and

steel production30 (1%)

Cementproduction130 (5%)

Waste disposal110 (5%)

Artisanal gold mining300 (13%)

Chlor-alkali172 (7%)

Source N Hg2+

/Total Hg(%) ± Std. Dev.

Cement Productiona 3 25 ± 4

Incinerator (medical)a 3 95 ± 5

Incinerator (municipal)a 8 78 ± 8

Coal-fired Utility Boilerb 19 67 ± 27

Anthropogenic Hg Emissions

Observed as Hg2+

a Stevens et al., 1996b Prestbo and Bloom, 1995

�Impregnated Filter

�Refluxing Mist Chamber

�Tubular Denuder

Ambient RGM Methodologies

Challenges Measuring RGM

�Reject much larger elemental component

�Method must be 1-2 orders of magnitude more

sensitive than total mercury methods

�Quantitatively pass RGM to the collector

�Exclude particulate phase mercury while avoiding

filter artifact

1 mm Annular Space

Etched Inner Surface

Quartz Annular Denuder

* Landis et al. Environ. Sci. Technol., 2002, 36, 3000-3009

SEM Micrographs of Quartz Surfaces

Laboratory Evaluation

Total RGM Loading Total Recovered Behind Denuder

HgCl 2 (ng)

0

2

4

6

8

10

12

14

97.2%

97.8%

Collection Efficiency for HgCl2

Collocated Manual Annular Denuder RGM (pg m-3)

0 25 50 75 100 125 150

Ma

nua

l A

nnu

lar

Denud

er

RG

M (

pg m

-3)

0

25

50

75

100

125

150

Front Denuder RGM (pg)

0 100 200 300 400 500

Both

De

nu

de

rs R

GM

(p

g)

0

100

200

300

400

500

< 12 Hours (93%)

> 12 Hours (83%)

(n= 47)

Annular Denuder Performance

RGM (pg m-3)

0 20 40 60 80 100

RG

M (

pg m

-3)

0

20

40

60

80

100

Both Denuders Heated

Y Heated; X Not Heated

Barrow, Alaska (2001)

Importance of Properly

Heating Sampling System

1 2 3 4 5 6 7 8 9 10 11 12

Part

icula

te H

g (

pg m

-3)

0

25

50

75

100

700

800

Hg 2

+ (

pg

m-3

)

0

50

100

150

200

250

Denuded HgP

Undenuded HgP

Hg+2

Collocated Denuded &

Undenuded Hg(p)

KCl Denuder

Method Detection LimitsField Blanks

N Mean (pg) Std Dev (pg)

66 2.22 1.24

Duration

(hours)

Air Volume

(m3)

MDL

(pg m-3)

1 0.6

2 1.2

6 3.6

12 7.2

2.1

4.1

0.7

0.3

10 LPM Flow Rate

Observed RGM Concentrations

SiteSite NN MaxMax(pg m(pg m--33))

Everglades, FLEverglades, FL 4545

Baltimore, MDBaltimore, MD 3030

RTP, NCRTP, NC 2626

138.7138.7

54.354.3

51.051.0

MeanMean(pg m(pg m--33))

MinMin(pg m(pg m--33))

Std DevStd Dev(pg m(pg m--33))

15.415.4

22.722.7

15.515.5

2.52.5

5.45.4

3.53.5

12.012.0

25.925.9

12.012.0

Field Monitoring Setup

Elutriators

Impactors

Quartz Thermal

Filter Pack

Sampling Box

Heaters

KCL - coated

Annular Denuders

Standard Filter Pack

Manual Denuder

Sampling Box

Analysis of Manual Denuder

Flow Diagram of Tekran 2537A

Mercury Analyzer

Zero

Air

Sample

Air

Manual

Injection

Port

Carrier

Gas

Mass Flow

Controller

Vent

Cell

Vent

Detector

Sample

Pump

Pump

Exhaust

Mass Flow

Meter

Dual

Cartridge

Assembly

B

A

Permeation

Source

Tekran System Description

� Model 2537A Vapor Phase Mercury Analyzer

– Semi-continuous Hg0 Measurements

– Gold Traps for Hg0 Pre-concentration

– Cold Vapor Atomic Fluorescence Spectrometer

� Model 1130 Speciation Unit

– KCl Thermal Annular Denuder (Hg2+)

– Zero Air Source & Pumping Module

� Model 1135 Particulate Unit

– Thermal Quartz Filter & Pyrolyzer Column

Automated Speciation Instrumentation

Typical External Installation

Typical Internal Installation

8-1

8-9

8-1

6

8-2

3

8-3

0

9-6

9-1

3

9-2

0

RG

M (

pg m

-3)

0

100

200

300

400

500

Hg

0 (

ng m

-3)

0

1

2

3

4

5

6

7

8

Hg

P (

pg m

-3)

0

50

100

150

200

250

RGM

Hg0

HgP

Mauna Loa Hg Time Series

7/31 – 9/20, 2001

Tekran System SOP

� Weekly- Replace: denuder, soda & lime trap, impactor frit, filters

- Clean: inlet glassware, impactor, couplers

- Check: trap performance, flows, heaters

- Conduct perm tube calibration

� Monthly- Manual injections (2537A, 1130 inlet)

� Bi-monthly- Replace RPF, zero air filters

� Six Months- Calibrate 2537A permeation tube

� Annual- Replace: 1130 Carbon traps, pump brushes, 2537A lamp

- Calibrate 2505 syringe, flow controllers

QA/QC Inlet Injection

Speciation Methods Summary

�KCl-Coated annular denuders quantity RGM without

known interference problems when following SOP

�RGM is thermally (~500°C) converted to Hg0

�Hg(p) is thermally (~800°C) converted to Hg0

� Low denuder MDL’s allow high-resolution sampling

�Manual method is inexpensive, simple, and mobile

�Tekran provides automated high-resolution data

Questions ???