1. Mercury Monitoring in Ambient Air F.H. Schaedlich
Introduction to Model 1130/35 Automated Ambient Air Speciated Mercury Monitor
F.H. Schaedlich
Rev: November 3, 2003
Tekran Inc.

2. Acknowledgements Matt Landis US EPA 1 Robert K. Stevens Florida DEP 2a
Tom Atkeson Florida DEP 2b
Eric Prestbo Frontier Geosciences 3
Steve Lindberg Oak Ridge Nat’l Labs 4
Gerald Keeler University of Michigan 5
1 Research Triangle Park, NC 27711
2a At US EPA, Research Triangle Park, NC 27711
2b Tallahassee, FL
414 Pontius Ave. N., Suite B, Seattle, WA 98109
PO Box 2008, Oak Ridge, TN
5 School of Public Health, 109 Observatory Street, MI

3. Total Gaseous Mercury Monitoring
Part 1
Total Gaseous Mercury Monitoring

4. Why measure parts per Quadrillion of Mercury ?
Mercury Monitoring in Ambient Air
Why measure parts per Quadrillion of Mercury ?
Mercury is one of the most potent neurotoxins known
Bio-accumulates up the food chain by factors of up to 10,000,000 times
Sub-ppt levels in air can accumulate to toxic ppm levels in fish
Levels are increasing worldwide
Long life in the atmosphere means that mercury emissions are of global concern
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5. Total Gaseous Mercury Monitoring
Originally implemented manually
Gold coated silica field cartridges
Analysis using dual stage thermal desorption with CVAFS (atomic fluorescence) detection
Gold preconcentration with AA (atomic absorption) detection had been shown to be subject to serious artifacts when attempting to measure ambient levels

6. Model 2537A Mercury Analyzer
Mercury Monitoring in Ambient Air
Model 2537A Mercury Analyzer
Automated implementation of gold/AF manual method
Instrument protected by US and international patents
Has largely supplanted manual cartridge methods
Provides continuous total gaseous (TGM) readings with update rate as low as minutes
Detection limit < 0.1 ng/m3 (5 min. samples)
Automatic recalibration with internal Hg0 permeation source
Capable of unattended operation for extended periods
Tekran Inc.

7. Mercury Monitoring in Ambient Air
Model 2537A Analyzer
Tekran Inc.

8. Principles of Operation
Mercury in sample gas is preconcentrated onto (pat’d) pure gold cartridge
Adsorbed mercury is thermally desorbed
Detected by atomic fluorescence detector
Two cartridges are used to alternately sample and desorb
No gaps in data stream

9. Flow Diagram of Model 2537A Mercury Analyzer (Pat’d)
Mercury Monitoring in Ambient Air
Flow Diagram of Model 2537A Mercury Analyzer (Pat’d)
Dual cartridges. One samples while the other is being desorbed. The roles are then reversed.
Calibration is performed using an internal permeation source. An injection port is available for manual saturated mercury vapour injections.
Sample flow is measured using a mass flow controller connected to a variable speed pump in a closed loop arrangement.
A full size tank of argon carrier lasts about 2 months.
Tekran Inc.

10. Pure Gold Cartridge (Pat’d)
Mercury Monitoring in Ambient Air
Pure Gold Cartridge (Pat’d)
Pure gold only is used as adsorbent
No quartz wool or silica
No memory effect
Extremely durable design
Lasts for years of continuous use
Cartridge design is protected by separate US and international patents
Tekran Inc.

11. Mercury Monitoring in Ambient Air
Pure Gold Cartridge
Tekran Inc.

12. Mercury Monitoring in Ambient Air
Atomic Fluorescence
Much more sensitive than atomic adsorption
MDL < 0.1 pg absolute
Not subject to interferences
AA requires some sort of compensation/correction scheme
Interfering compounds (e.g. SO2, O3, organics) often present in concentrations thousands of times higher than Hg
Inherently linear
Detector linear over >5 orders of magnitude
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13. Tekran AF Detector Features
Mercury Monitoring in Ambient Air
Tekran AF Detector Features
Most sensitive, most stable and lowest noise AF detector available
Some reasons why:
Temperature controlled lamp block
Optical feedback loop for constant lamp intensity
Optical path purged with argon for stability
< 10 ml/min required for optical purge
Magnetic shield on photomultiplier tube
Tekran Inc.

14. Mercury Monitoring in Ambient Air
Tekran AF Detector
Tekran Inc.

15. Internal Permeation Source
Mercury Monitoring in Ambient Air
Internal Permeation Source
Allows automated, unattended calibrations
Ensures that analyzer results are always accurate
Allows standard additions to sample gas
Ensures that analyzer is working properly even when confronted with difficult matrices
Long life permeation tube
Low emission rate: Approx 30 µg/yr
Theoretical life: thousands of years!
Special auto-flush feature ensures no carryover after activation
Tekran Inc.

16. Perm Source Flow Diagram
Mercury Monitoring in Ambient Air
Perm Source Flow Diagram
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17. Integrates into Monitoring Networks
Designed to look and operate like other continuous ambient air monitors
Rack mountable
Easy to use interface
Two analog chart outputs
Serial output provides hi-resolution results and:
Instrument performance variables
Full record of each calibration
Record of instrument setup parameters

18. Operational Characteristics
Mercury Monitoring in Ambient Air
Operational Characteristics
Lamp lasts in excess of one year of continuous operation
Inexpensive, multi-sourced
Unlimited shelf life
No special isotopes required
No zero drift !
Each reading is an integrated peak value
Detector drift does not affect results
Tekran Inc.

19. Mercury Monitoring in Ambient Air
Reporting Basis
Reports data readings based on sample volumes corrected to 0°C, 760 mm
All Hg concentrations in the literature are reported on this volume basis
No reading-by-reading temperature and pressure corrections required to normalize data
Reporting at other conditions (e.g. 20 °C) is possible simply by changing internal menu setting
Tekran Inc.

20. True Ambient Measurement
Tekran Model 2537A is the only analyzer available that is capable of accurately and precisely measuring true ambient mercury values
Can measure mercury in actual gas matrices
Virtually any analyzer (even uncompensated AA units) can give correct answers when measuring mercury in zero air!

21. Other Applications
With appropriate accessories and front ends the Tekran Model 2537A can perform:
Process gas monitoring
Continuous emissions monitoring (CEM)
Mercury flux measurement
Both chamber & gradient methods!
Standard additions
Speciation: ionic (reactive gaseous) mercury
Speciation: particulate bound mercury

22. Sample Data: Chlor-Alkali Plant
Mercury Monitoring in Ambient Air
Sample Data: Chlor-Alkali Plant
Plot of wind direction vs. ambient mercury values
Two months of continuous monitoring
Plant is located 18 miles distant
Fish consumption advisories in effect
Fish levels were > 1.5 ppm even though air readings were only slightly elevated
Global background:~1.5 ng/m3
This plant is in North Carolina.
Tekran Inc.

23. Depletions of Mercury in the Arctic
The 2537A is capable
of extremely precise
measurement of even
sub-ambient readings.
In cases where two instruments are
running, they track each other very closely.

24. Validation of Depletion Events
This line shows the % recovery of periodic automated standard additions of elemental mercury to the sample matrix. The recoveries are ~ 100%, yielding absolute confidence that these unusual values represented a genuine, hitherto unknown phenomenon.

25. Reactive Gaseous Mercury Monitoring
Part 2
Reactive Gaseous Mercury Monitoring

26. Mercury Monitoring in Ambient Air
Tekran’s Objectives
Development of an automated method to measure and differentiate different forms of mercury in ambient air
Reactive Gaseous Mercury (RGM)
Fine Fraction Particulate Mercury (HgP)
Elemental mercury (Hg0)
Tekran Inc.

27. Why Ambient Air Mercury Speciation ?
Mercury Monitoring in Ambient Air
Why Ambient Air Mercury Speciation ?
Different forms of gaseous Hg have vastly different behaviors and environmental impacts
Forms can interconvert in the atmosphere and in various reservoirs
Classes of mercury in ambient air:
Elemental mercury: Hg0, GEM
Reactive mercury: HgII, RGM, Hg2+
Particulate mercury: HgP, TPM
Won’t talk about particulate mercury due to time constraints.
Tekran Inc.

28. Mercury Monitoring in Ambient Air
Elemental Mercury: Hg0
Typically 90+% of atmospheric Hg loadings
Relatively inert. Long residence time
Hg0 sources impact large areas
Sources: chlor-alkali plants, gold and Hg mining, thermal power plants
Tekran Inc.

29. Reactive Mercury: Hg(II) or RGM
Mercury Monitoring in Ambient Air
Reactive Mercury: Hg(II) or RGM
Consists of ionic, water soluble forms, primarily HgCl2
Usually only a few percent of total gaseous mercury present in the atmosphere
Short range: deposits relatively close to the source of emission
Primary sources: Coal burning power plants, waste incinerators, chlor-alkali plants
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30. Difficulties Measuring RGM
Mercury Monitoring in Ambient Air
Difficulties Measuring RGM
Method must be 1-2 orders of magnitude more sensitive than total mercury methods
Reject much larger elemental component
Must exclude particulate bound mercury, however, conventional particulate filters cannot pass RGM
Apparatus must pass RGM to the collector quantitatively. (RGM is extremely “sticky”)
Tekran Inc.

31. Model 1130 - Principles of Operation
Mercury Monitoring in Ambient Air
Model Principles of Operation
Patented by Tekran. (US 6,475,802)
Quartz, KCl coated annular denuder is thermally desorbed and regenerated
Sampling Phase
Absorbs RGM while passing all elemental Hg
Model 2537A reads Hg0 during this phase
Desorption/Analysis Phase
Zero air used as carrier
RGM released as elemental mercury
Tekran Inc.

32. Mercury Monitoring in Ambient Air
RGM Sampling Phase
Denuder is slightly warm
Inlet slightly warm
Denuder captures all RGM while passing Hg0
Total sample flow is 10 lpm
Analyzer measures Hg0 during this time
Tekran Inc.

33. Mercury Monitoring in Ambient Air
Analysis Phase
Denuder is heated to 500°C
Inlet heated to clean up-stream glassware. (75 °C)
Denuder releases captured RGM as Hg0
Excess zero air flow and heat cleans upstream components
Instrument measures accumulated RGM as Hg0
Tekran Inc.

34. Quartz Denuder Assembly
Mercury Monitoring in Ambient Air
Quartz Denuder Assembly
Elutriator Jet
Impactor
Body & Disk
Zero Air
Inlet
Sample Air
Annulus
Elbow
(not used with 1135)
Coupler
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35. Model 1130 Speciation System
Mercury Monitoring in Ambient Air
Model Speciation System
Denuder Module (top)
Located out of doors
Contains denuder element within high performance oven
Impactor inlet removes coarse particles (> 2.5 um)
Climate controlled enclosure
Tekran Inc.

36. Model 1130 Speciation System
Mercury Monitoring in Ambient Air
Model Speciation System
Pump Module (bottom)
Located beside 2537A
Provides extra flow required during sampling
Generates the zero air required during desorption
Also provides all zero air required by Model 2537A!
Heated line (not shown)
25 ft. length connects the two modules
Tekran Inc.

37. Instrument Characteristics
Fully automated, unattended operation
Denuder exchanged every 1 or 2 weeks
Operates in any environment
Polar (Greenland, USA, Canada, Antarctica)
Sub-tropical (Florida Everglades)
Desert (Nevada)
Marine (ocean cruises)
High altitude (Mauna Loa)

38. Data Characteristics
High time resolution Hg0 data provided during sampling phase
Typically every 2½ or 5 min
Data is averaged to yield one Hg0 point per sampling period
Single RGM integrated value every sample period
Sample period: 0.5 – 3 hours
Analysis Period: 25 – 60 min
Data values are for the exact same time period

39. Method Validation
Method was developed over a two year period at Tekran before being announced
Tested using both HgCl2 and HgI2 as surrogates for RGM
Two prototype units bought by State of Florida
Units evaluated by Frontier Geosciences in Seattle under contract with Florida DEP
Subsequent field testing by Keeler et al, University of Michigan & Lindberg et al., ORNL

40. Mercury Monitoring in Ambient Air
Lab RGM Apparatus - (1997)
Denuder
This is our RGM lab setup, with one denuder and one packed backup trap.
Fortunately, Tekran is good at packaging something like this.
Model 2537A
Coffee Can
Tekran Inc.

41. Preliminary Results - Toronto
Mercury Monitoring in Ambient Air
Preliminary Results - Toronto
Tekran Inc.

42. Preliminary Results - Toronto
Mercury Monitoring in Ambient Air
Preliminary Results - Toronto
Two curves have been shifted horizontally for visibility
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43. Lab Testing: Frontier Geosciences
Mercury Monitoring in Ambient Air
Lab Testing: Frontier Geosciences
Tekran Inc.

44. Seattle RGM Data Municipal Incinerator Plume
Courtesy: Frontier Geosciences

45. Mercury Levels - Rural Michigan
Courtesy: UMAQL

46. Particulate Mercury Monitoring

47. Mercury Monitoring in Ambient Air
Why Measure HgP ?
Particulate bound mercury (TPM / HgP) is created directly by some industrial processes and also formed downwind of sources by the combination of mercury with existing particulates
HgP is removed even more rapidly via wet and dry deposition than is RGM
Tekran Inc.

48. Particulate Mercury: TPM
Mercury Monitoring in Ambient Air
Particulate Mercury: TPM
Consists of various compounds of mercury bound onto particles
Size range: Generally thought to be < 3 um
Usually only a few percent of total mercury present in the atmosphere
Short range: deposits relatively close to the source of emission
Tekran Inc.

49. Difficulties Measuring HgP
Mercury Monitoring in Ambient Air
Difficulties Measuring HgP
Method must be 1-2 orders of magnitude more sensitive than total mercury methods
Must reject much larger elemental component
Method must also exclude reactive gaseous mercury, however, normal particulate filters have problems in that they retain some RGM
Virtually all conventional measurement methods have recently been found to have serious analytical artifacts due to RGM (Landis, et al, ES&T, 2002)
Artifact is non-quantitative and cannot be subtracted or corrected
Tekran Inc.

50. Model 1135 - Principles of Operation
Mercury Monitoring in Ambient Air
Model Principles of Operation
Sampling Phase
Sample passes through impactor to eliminate coarse particles (> 2.5 um)
Coated denuder captures RGM and eliminates RGM artifact
Quartz, Regenerable Particulate Filter (RPF) captures fine fraction (< 2.5 um) particulates
Desorption/Analysis Phase
Zero air used as carrier
Downstream pyrolyser is activated first
RPF is then heated to desorb captured particulates
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51. RPF Quartz wool captures bulk of particulate matter
Quartz membrane filter disk
Pyrolyzer
(quartz chips)
Air Gap
Tail
Inlet
(from denuder)
Quartz wool captures bulk of particulate matter
Quartz filter membrane provides sharp cut-off (<0.1 um)
Built in pyrolyzer section converts desorbed species to Hg0
Carbon based particulate matter on the filter is oxidized to CO2 during desorption cycle
Tail provides cooling

52. Model 1135 – Particulate Mercury Monitor
Unit stacks on top of Model 1130
Allows simultaneous deter-mination of Hg0, RGM and HgP
Detection limit < 2 pg/m3

53. Model 1130 & Model Flow Path

54. Ambient Air Speciation

55. Sample Installations
Figure 1 - Temporary Model 1130/35 Installation (AES, Quebec Canada)
Figure 2 - Permanent Arctic Model Installation (NOAA, Barrow Alaska)
Figure 3 - Model 1130-P (prototype) Mounted on roof of trailer (US EPA, NERL)
Figure 4 - Temporary Model P Installation (US EPA & Florida DEP)
Figure 5 - Model 1130-P sampling in Antarctica (GKSS & AWI, Germany)

56. Mercury Monitoring in Ambient Air
Conclusion
Measurement of mercury species at ambient levels is now practical
Equipment has shown its utility and reliability in a wide variety of sampling situations around the world
Some additional commitment in resources is required to implement a successful speciated mercury monitoring program
Tekran Inc.

57. Contact fhs@tekran.com
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