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Elgiar TR, Lyman SN, Andron TD, Gratz L, Hallar AG, Horvat M, Vijayakumaran Nair S, O'Neil T, Volkamer R, Živković I. Traceable Calibration of Atmospheric Oxidized Mercury Measurements. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:10706-10716. [PMID: 38850513 DOI: 10.1021/acs.est.4c02209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2024]
Abstract
Most previous measurements of oxidized mercury were collected using a method now known to be biased low. In this study, a dual-channel system with an oxidized mercury detection limit of 6-12 pg m-3 was deployed alongside a permeation tube-based automated calibrator at a mountain top site in Steamboat Springs Colorado, USA, in 2021 and 2022. Permeation tubes containing elemental mercury and mercury halides were characterized via an International System of Units (SI)-traceable gravimetric method and gas chromatography/mass spectrometry before deployment in the calibrator. The dual-channel system recovered 97 ± 4 and 100 ± 8% (±standard deviation) of injected elemental mercury and HgBr2, respectively. Total Hg permeation rates and Hg speciation from the gravimetric method, the chromatography system, the dual-channel system, and an independent SI-traceable measurement method performed at the Jožef Stefan Institute laboratory were all comparable within the respective uncertainties of each method. These are the first measurements of oxidized mercury at low environmental concentrations that have been verified against an SI-traceable calibration system in field conditions while sampling ambient air, and they show that accurate, routinely calibrated oxidized mercury measurements are achievable.
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Affiliation(s)
- Tyler R Elgiar
- Bingham Research Center, Utah State University, Vernal, Utah 84078, United States
| | - Seth N Lyman
- Bingham Research Center, Utah State University, Vernal, Utah 84078, United States
- Department of Chemistry and Biochemistry, Utah State University, Logan ,Utah 84322, United States
| | - Teodor D Andron
- JoŽef Stefan Institute, Ljubljana 1000, Slovenia
- JoŽef Stefan International Postgraduate School, Ljubljana 1000, Slovenia
| | - Lynne Gratz
- Reed College, Portland, Oregon 97202, United States
| | - A Gannet Hallar
- Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Milena Horvat
- JoŽef Stefan Institute, Ljubljana 1000, Slovenia
- JoŽef Stefan International Postgraduate School, Ljubljana 1000, Slovenia
| | - Sreekanth Vijayakumaran Nair
- JoŽef Stefan Institute, Ljubljana 1000, Slovenia
- JoŽef Stefan International Postgraduate School, Ljubljana 1000, Slovenia
| | - Trevor O'Neil
- Bingham Research Center, Utah State University, Vernal, Utah 84078, United States
| | - Rainer Volkamer
- Department of Chemistry & CIRES, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Igor Živković
- JoŽef Stefan Institute, Ljubljana 1000, Slovenia
- JoŽef Stefan International Postgraduate School, Ljubljana 1000, Slovenia
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Vijayakumaran Nair S, Gačnik J, Živković I, Andron TD, Ali SW, Kotnik J, Horvat M. Application of traceable calibration for gaseous oxidized mercury in air. Anal Chim Acta 2024; 1288:342168. [PMID: 38220300 DOI: 10.1016/j.aca.2023.342168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/28/2023] [Accepted: 12/17/2023] [Indexed: 01/16/2024]
Abstract
BACKGROUND The current speciation methods for mercury (Hg) measurements are fraught with considerable uncertainty, from sample collection to calibration. High reactivity of gaseous oxidized Hg (GOM) species and their ultra-trace level presence makes them difficult to sample and calibrate. Given that improper calibration may lead to measurement biases, reliable and metrologically traceable calibration methods are required for accurately quantifying GOM in air. In the present study, we applied the recently developed calibration method based on non-thermal plasma oxidation of elemental Hg, to a commercially available Hg air speciation system for actual environmental measurements of GOM for the first time. RESULTS Hg species such as HgO, HgCl2, and HgBr2 were produced with trace amounts of reactant gases (oxygen and electrolytically produced chlorine and bromine) and the production was driven by plasma-assisted oxidation. The plasma oxidation efficiency of elemental Hg with oxygen was 98.5 ± 7.5 % (k = 2), while that for chlorine and bromine was 96.8 ± 6.9 % (k = 2) and 97.4 ± 9.6 % (k = 2), respectively. The calibration method was tested against the internal permeation (Hg0) source of the Tekran 2537B Hg analyzer on-field by loading HgO to different KCl-coated denuders using the plasma. GOM concentrations were measured using the Tekran speciation system. With internal calibration, concentrations were up to 9.1 % lower than those in plasma calibration, thereby emphasizing the importance of the calibration strategy. Measurement uncertainty (k = 2) further emphasizes this distinction. Internal calibration measurement uncertainty was 36.8 %, while plasma calibration boasted lower uncertainty at 13.8 %. SIGNIFICANCE The non-thermal plasma calibration strategy, as a unique and discrete calibration method traceable to the NIST SRM 3133 for ambient air GOM measurements, provide a higher level of confidence in the accuracy of GOM measurements with several advantages over other methods. Calibrations at extreme low concentrations (<100 pg) are possible with this method relevant to ambient air GOM concentrations.
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Affiliation(s)
- Sreekanth Vijayakumaran Nair
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia
| | - Jan Gačnik
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia
| | - Igor Živković
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia
| | - Teodor Daniel Andron
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia
| | - Saeed Waqar Ali
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia
| | - Jože Kotnik
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia
| | - Milena Horvat
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia.
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