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ARL Mercury Measurements in the mid-Atlantic and Gulf of Mexico Regions: Status and Update. Winston Luke, Paul Kelley, Mark Cohen NOAA/Air Resources Laboratory Prepared for EPA/NOAA Meeting Silver Spring, June 24, 2009. Measurements at Beltsville, MD CASTNet Site. Monitoring sites.

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Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

ARL Mercury Measurements in the mid-Atlantic and Gulf of Mexico Regions: Status and Update

Winston Luke, Paul Kelley, Mark Cohen

NOAA/Air Resources Laboratory

Prepared for EPA/NOAA Meeting

Silver Spring, June 24, 2009



Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Monitoring sites

rural AQS

other AQS

NADP/MDN

CASTNet

Symbol color

indicates type

of mercury source

Hg site

IMPROVE

coal

incinerator

metals

manuf/other

Symbol size and

shape indicates

1999 mercury

emissions, kg/yr

1 - 50

50 - 100

100 - 200

200 – 400

400 - 700

700 – 1000

> 1000

Beltsville, MD

CASTNet Site

Harford County MSW Incin

Brandon Shores

and H.A. Wagner

100 miles

from DC

Montgomery County

MSW Incin

Eddystone

Dickerson

Arlington - Pentagon MSW Incin

Possum Point

Beltsville monitoring site

Chalk Point

Morgantown

Bremo


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Site is impacted by a variety of local-regional sources with unique emissions characteristics. Coupled chemical-meteorological analysis will yield important insights into mercury emissions, transport, transformation, and removal at the site.


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

As at Grand Bay, higher RGM is typically associated with high O3 concentrations and chemically aged air masses, suggesting that reactive gaseous mercury concentrations at the site reflect the influence of regional continental emissions.



Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)

All back trajectories run

at 12 km resolution


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)



Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)



Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)



Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)



Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

size/shape of symbol denotes amount of mercury emitted (kg/yr)

color of symbol denotes type of mercury source

Back-trajectories

starting at the

indicated fraction

of the mixed layer

height. Circles on

the trajectories mark the hourly positions

0.1

coal-fired power plants

10 - 50

0.3

other fuel combustion

50 - 100

0.5

waste incineration

100 – 200

0.7

metallurgical

200 - 400

manufacturing & other

0.9

400 - 600

Large Point Sources of Reactive Gaseous Mercury (RGM) Emissions Based on the 2002 U.S EPA

National Emissions Inventory (NEI)





Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Issues/Updates/Challenges at Beltsville (kg/yr)

  • The more polluted environment at Beltsville leads to significant trap bias

  • in Tekran 2537. Cleaning gold traps, even in Aqua Regia, provides only temporary improvement. Traps must really be replaced every 6 months ($1400/pair per instrument).

  • We will explore the option of making our own gold traps to save considerable expense.

  • EPA-purchased 2537B detector has been plagued by more persistent problems than any of the 2537A’s fielded by NOAA at Grand Bay or Beltsville. Problems are mostly transient and so far have defied diagnosis at Tekran. It may be necessary to return the instrument for a thorough analysis and repair.

  • Power stability at Beltsville, for the most part acceptable, deteriorated in Summer 2008. We will monitor stability closely this Summer.

  • We are collaborating with Mark Engle and Allan Kolker, USGS-Reston, to collect MOUDI and Hi-Vol aerosol samples periodically at the site.



Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

View from top of 10 m tower looking at the southerly (prevailing wind) sampling sector over the U.S. Fish and Wildlife Service Pavilion at Grand Bay NERR


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

As in 2007, most pronounced correlation was between ozone and RGM, especially during the Spring (March-May).

Similar concentrations of RGM and O3 were observed in Springtime 2007 and 2008. Higher RGM in Summer ’08 than Summer ‘07

Spring 2007

Spring 2008


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Across all seasons, higher RGM levels were associated with drier air parcels containing aged emissions. Together with the RGM/O3 correlation, this suggests that aged continental emissions, not extremely local sources, are responsible for enhanced RGM at the site.

Downward mixing from the middle and upper trop may be involved as well.

Lack of increase of FPM at high RH suggests no phase partitioning of RGM to small particles at high RH, but sea salt aerosols may take up RGM.


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Two systems were configured identically (pink), then System 2 was fitted with a 10-micron cut point elutriator (blue) over the course of several days.

Results suggest that there may be as much mercury in the coarse (sea salt) aerosol fraction as in the fine fraction.

Studies will be repeated periodically at the site.


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Upgrades to the Site 2 was fitted with a 10-micron cut point elutriator (blue) over the course of several days.

  • Under the auspices of the Mississippi Department of Environmental Quality, precipitation collectors will be added at the Grand Bay NERR for the measurement of:

  • Rainfall amounts

  • Ott Pluvio gauge

  • Major ions in precipitation (NTN)

  • Aerochem collector, upgrade to NCON when approved

  • Total mercury and trace metals in precipitation (MDN)

  • Aerochem collector, upgrade to NCON when approved

  • Siting criteria have been reviewed and approved, and purchase requisitions have been prepared for site improvement and instrument procurement.


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Planned Intensive, Spring-Summer 2010 2 was fitted with a 10-micron cut point elutriator (blue) over the course of several days.

  • Collaborative research involving NOAA, GA Tech, Florida State University, and others

  • Focus is on the role of halogen species in the MBL and their oxidation of

  • Hg(0) to RGM species, at the surface and aloft.

  • Components include ongoing speciated mercury and ancillary trace gas measurements at the NERR. A 3-wavelength nephelometer will be added, as will radiosonde/ozonesonde launches from the NERR to determine thermal and chemical structure of the troposphere.

  • Greg Huey (GA Tech) will measure Br2, BrO, BrCl, and HOBr at the surface via Chemical Ionization Mass Spectrometry.

  • Tony Hynes (U. Miami) will attempt to measure total and speciated RGM at the surface and aloft using coated and uncoated denuders using the technique of programmable thermal desorption.

  • Other measurements and participants to be added as work progresses.


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Data Reduction Scheme at ARL/HQ 2 was fitted with a 10-micron cut point elutriator (blue) over the course of several days.

  • A batch file is executed that first concatenates all the five-minute data files

  • During review of the raw data, three files (.bGEM, .bRGM, .bFPM) are produced by-hand that contain the JDD start and end times of any period of bad data. The program then reads these files and flags the data

  • A FORTRAN program is then run in batch mode

  • All automatic calibrations are parsed out and written to a

  • separate file

  • GEM trap bias is calculated for each hour. If it exceeds 10%

  • then each five-minute period in the GEM cycle and each period in the

  • desorb cycle is adjusted to increase the low-trap result up to the

  • proper ratio.

  • GEM for the hour is just the average of the 12 five-minute results.

  • FPM for the hour is the sum of the three FPM desorbs minus three

  • times the pyrolyzer value.


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Data Reduction Scheme at ARL/HQ (cont’d) 2 was fitted with a 10-micron cut point elutriator (blue) over the course of several days.

RGM for the hour is the sum of the three RGM desorbs minus three

times the second flush value. If flush values exceed 1.0 ngm/m3 then

there is a leak in the system and the GEM, RGM & FPM are all

flagged with -555.55.

If there has been more than 2.1 hours since the previous desorb and

greater than 1.1 hours since the last automatic calibration, then the

RGM & FPM are flagged with -333.33.

If average GEM for the hour is less than 0.8ngm/m3 then GEM,

RGM & FPM are flagged with -888.88.

Hours where results are missing or there is an unexpected number

of GEM / RGM / FPM cycles are flagged -999.99.

Each row in the results file (.prHg) is assigned a JDD & decimal year

timestamp for the midpoint of the hour, as well as the MM/DD/YY

HH/MM/SS values. Start and end times of each desorb are also

reported, along with trap bias ratio.


Arl mercury measurements in the mid atlantic and gulf of mexico regions status and update

Data Reduction Scheme at ARL/HQ (cont’d) 2 was fitted with a 10-micron cut point elutriator (blue) over the course of several days.

A “.stHg” file is generated that contains statistics on the processed

data. This includes the JDD start & end times used to flag data, any

warnings such as high or low GEM readings, high or low flow

volumes, low baseline voltages, multiple peaks or over-ranges, and

any periods that data is automatically rejected.

Calibration times and intervals between calibrations are listed.

Time of power resets are also listed.

At the end of this file is a listing of overall statistics such as: number

of A low bias hours, number of B low bias hours, number of leaky

hours, number of hours where the time between desorbs was outside

limits, number of hours where the proper timing sequence was not

found, number of hours that had negative desorb results for RGM or

FPM, and total number of valid processed hours.