Comparability of calibration strategies for measuring mercury concentrations in gas emission sources and the atmosphere

Abstract. A primary mercury gas standard was developed at VSL to establish an SI-traceable reference point for mercury concentrations at emission and background levels in the atmosphere. The majority of mercury concentration measurements are currently made traceable to the empirically determined vapour pressure of mercury. The primary mercury gas standard can be used for the accurate and precise calibration of analytical systems used for measuring mercury concentrations in air. It has been especially developed to support measurements related to ambient air monitoring (1 ng m−3–2 ng m−3), indoor and workplace related mercury concentration levels according to health standards (from 50 ng m−3 upwards) as well as to stationary source emissions (from 1 µg m−3 upwards). The primary mercury gas standard is based on diffusion according to ISO 6154-8. Calibration gas mixtures are obtained by combining calibrated mass flows of nitrogen and air through a generator holding diffusion cells, containing elemental mercury. In this paper, we present the results of comparisons between the primary standard and mercury calibration methods maintained by NPL, a National Metrology Institute (NMI), and JSI, a Designated Institute (DI). The calibration methods currently used at NPL and JSI are based on the bell-jar calibration apparatus in combination with the Dumarey equation or a NIST reference material. For the comparisons, mercury was sampled on sorbent traps to obtain transfer standards with levels between 2 ng and 1000 ng with an expanded uncertainty not exceeding 3 % (k = 2). The comparisons performed show that the results for the primary standard and the NIST reference material are comparable, whereas a difference of −8 % exists between results traceable to the primary standard and the Dumarey equation.

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Comparability of calibration strategies for measuring mercury concentrations in gas emission sources and the atmosphere

Atmospheric Measurement Techniques ◽

10.5194/amt-14-2317-2021 ◽

2021 ◽

Vol 14 (3) ◽

pp. 2317-2326

Author(s):

Iris de Krom ◽

Wijnand Bavius ◽

Ruben Ziel ◽

Elizabeth A. McGhee ◽

Richard J. C. Brown ◽

...

Keyword(s):

Reference Material ◽

Mercury Concentration ◽

International System ◽

Elemental Mercury ◽

Ambient Air ◽

The United States ◽

National Metrology Institute ◽

Calibration Methods ◽

System Of Units ◽

Gas Standard

Abstract. A primary mercury gas standard was developed at Van Swinden Laboratory (VSL) to establish an International System of Units (SI)-traceable reference point for mercury concentrations at emission and background levels in the atmosphere. The majority of mercury concentration measurements are currently made traceable to the empirically determined vapour pressure of mercury. The primary mercury gas standard can be used for the accurate and precise calibration of analytical systems used for measuring mercury concentrations in air. It has been especially developed to support measurements related to ambient air monitoring (1–2 ng m−3), indoor and workplace-related mercury concentration levels according to health standards (from 50 ng m−3 upwards) as well as stationary source emissions (from 1 µg m−3 upwards). The primary mercury gas standard is based on diffusion according to ISO 6154-8. Calibration gas mixtures are obtained by combining calibrated mass flows of nitrogen and air through a generator holding diffusion cells containing elemental mercury. In this paper, we present the results of comparisons between the primary gas standard and mercury calibration methods maintained by NPL (National Physical Laboratory in the United Kingdom), a National Metrology Institute (NMI), and the Jozef Stefan Institute (JSI), a Designated Institute (DI). The calibration methods currently used at NPL and JSI are based on the bell-jar calibration apparatus in combination with the Dumarey equation or a NIST (National Institute of Standards and Technology in the United States) reference material. For the comparisons, mercury was sampled on sorbent traps to obtain transfer standards with levels between 2 and 1000 ng with an expanded uncertainty not exceeding 3 % (k=2). The comparisons performed show that the results for the primary gas standard and the NIST reference material are comparable, whereas a difference of −8 % exists between results traceable to the primary gas standard and the Dumarey equation.

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Ambient air. Monitoring the effects of genetically modified organisms (GMO). Pollen monitoring

10.3403/30309976 ◽

2015 ◽

Keyword(s):

Genetically Modified Organisms ◽

Genetically Modified ◽

Ambient Air ◽

Air Monitoring ◽

Pollen Monitoring ◽

Ambient Air Monitoring

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Technical evaluation of the TSCA Ambient Air Monitoring Program. [Toxic Substances Control Act (TSCA)]

10.2172/5122074 ◽

1992 ◽

Author(s):

L L Smith

Keyword(s):

Monitoring Program ◽

Ambient Air ◽

Air Monitoring ◽

Toxic Substances ◽

Ambient Air Monitoring ◽

Technical Evaluation ◽

Toxic Substances Control Act

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Air Concentrations of Gaseous Elemental Mercury and Vegetation–Air Fluxes within Saltmarshes of the Tagus Estuary, Portugal

Atmosphere ◽

10.3390/atmos12020228 ◽

2021 ◽

Vol 12 (2) ◽

pp. 228

Author(s):

Rute Cesário ◽

Nelson J. O’Driscoll ◽

Sara Justino ◽

Claire E. Wilson ◽

Carlos E. Monteiro ◽

...

Keyword(s):

Leaf Area ◽

Elemental Mercury ◽

Ambient Air ◽

Tagus Estuary ◽

Contaminated Site ◽

Gaseous Elemental Mercury ◽

Mercury Flux ◽

Sarcocornia Fruticosa ◽

Air Concentrations

In situ air concentrations of gaseous elemental mercury (Hg(0)) and vegetation–atmosphere fluxes were quantified in both high (Cala Norte, CN) and low-to-moderate (Alcochete, ALC) Hg-contaminated saltmarsh areas of the Tagus estuary colonized by plant species Halimione portulacoides (Hp) and Sarcocornia fruticosa (Sf). Atmospheric Hg(0) ranged between 1.08–18.15 ng m−3 in CN and 1.18–3.53 ng m−3 in ALC. In CN, most of the high Hg(0) levels occurred during nighttime, while the opposite was observed at ALC, suggesting that photoreduction was not driving the air Hg(0) concentrations at the contaminated site. Vegetation–air Hg(0) fluxes were low in ALC and ranged from −0.76 to 1.52 ng m−2 (leaf area) h−1 for Hp and from −0.40 to 1.28 ng m−2 (leaf area) h−1 for Sf. In CN, higher Hg fluxes were observed for both plants, ranging from −9.90 to 15.45 ng m−2 (leaf area) h−1 for Hp and from −8.93 to 12.58 ng m−2 (leaf area) h−1 for Sf. Mercury flux results at CN were considered less reliable due to large and fast variations in the ambient air concentrations of Hg(0), which may have been influenced by emissions from the nearby chlor-alkali plant, or historical contamination. Improved experimental setup, the influence of high local Hg concentrations and the seasonal activity of the plants must be considered when assessing vegetation–air Hg(0) fluxes in Hg-contaminated areas.

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