The effects of meteorological parameters and diffusive barrier reuse on the sampling rate of a passive air sampler for gaseous mercury

McLagan, David S.; Mitchell, Carl P. J.; Huang, Haiyong; Hussain, Batual Abdul; Lei, Ying Duan; Wania, Frank

doi:10.5194/amt-10-3651-2017

Cited by 35 publications

(64 citation statements)

References 30 publications

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“…The variability of the maximum uncertainty of the PAS (8.7 ± 505 5.7 %) was improved by the application of a temperature and wind speed adjusted SR (Eq. 3) recommended by McLagan et al (2017b). This is in the same range as uncertainties attributed to active measurement instruments (Aspmo et al, 2005;Slemr et al, 2015;Temme et al, 2007) and is unprecedented in gaseous Hg passive air sampling (McLagan et al, 2016a).…”

Section: Recommendations and Conclusionsupporting

confidence: 57%

“…The network now includes over 40 sites across all seven continents (Pozo et al, 2006;55 Shunthirasingham et al, 2010;Herkert et al 2018 (McLagan et al, 2016b). Also the variability of its sampling rate (SR; volume of air effectively stripped of gaseous Hg per unit 60 time) caused by meteorological parameters is small, increasing slightly with both temperature and wind speed across ranges relevant to outdoor deployments (McLagan et al, 2017b).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Global evaluation and calibration of a passive air sampler for gaseous mercury

McLagan¹,

Mitchell²,

Steffen³

et al. 2018

Preprint

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Abstract. Passive air samplers (PASs) for gaseous mercury (Hg) were deployed for time periods between 1 month and 1 year at 20 sites across the globe with continuous atmospheric Hg monitoring using active Tekran instruments. The purpose was to evaluate the accuracy of the PAS vis-à-vis the industry standard active instruments and to determine a sampling rate (SR; the volume of air stripped of gaseous Hg per unit of time) that is applicable across a broad variety of 5 conditions. The sites spanned a wide range of latitudes, altitudes, meteorological conditions, and gaseous Hg concentrations. Precision, based on 378 replicated deployments performed by numerous personnel at multiple sites, is 3.6 ± 3.0 % * , confirming the PAS's excellent reproducibility and ease-of-use. Using a SR previously determined at a single site, gaseous Hg concentrations derived from the globally distributed PASs deviate from Tekran-based 10 concentrations by 14.2 ± 10 %. A recalibration using the entire new data set yields a slightly higher SR of 0.1354 ± 0.016 m 3 day -1 . When concentrations are derived from the PAS using this revised SR the difference is reduced to 8.8 ± 7.5 %. At the mean gaseous Hg concentration across the study sites of 1.54 ng m -3 , this represents an ability to resolve concentrations to within 0.13 ng . m -3 . Adjusting the sampling rate to deployment specific temperatures and wind speeds does 15 not decrease the difference in active-passive concentration further (8.7 ± 5.7 %), but reduces its variability by leading to better agreement in Hg concentrations measured at sites with very high and very low temperatures and very high wind speeds. This value (8.7 ± 5.7 %) represents a conservative assessment of the overall uncertainty of the PAS due to inherent uncertainties of the Tekran instruments. Going forward, the recalibrated SR adjusted for temperature and wind speed 20 should be used, especially if conditions are highly variable or deviate considerably from the average of the deployments in this study (9.89 °C, 3.41 m s -1 ). Overall, the study demonstrates that the sampler is capable of recording background gaseous Hg concentrations across a wide range of environmental conditions with accuracy similar to that of industry standard active sampling instruments. Results at sites with active speciation units were inconclusive on whether the PASs 25 take up total gaseous Hg or solely gaseous elemental Hg primarily because gaseous oxidized Hg concentrations were in a similar range as the uncertainty of the PAS.* subscripted numbers are not significant, but are reported to reduce rounding errors in subsequent studies (see Section 2.3 for details) Atmos. Chem. Phys. Discuss., https://doi

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Section: Recommendations and Conclusionsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Global evaluation and calibration of a passive air sampler for gaseous mercury

McLagan¹,

Mitchell²,

Steffen³

et al. 2018

Preprint

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“…Total Hg in the HGR-AC sorbent was quantified using an Automated Mercury Analyzer (AMA254, Leco Instruments) according to USEPA method 7473 (USEPA 2007). Full details of the method for analyzing this particular sorbent can be found elsewhere (McLagan et al 2017a(McLagan et al , 2017b. All samples were adjusted for field blank concentrations, which overall were low at 0.4 ± 0.2 ng .…”

Section: Discussionmentioning

confidence: 99%

Identifying and evaluating urban mercury emission sources through passive sampler-based mapping of atmospheric concentrations

McLagan

Hussain

Huang

et al. 2018

Environ. Res. Lett.

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Beyond emissions from coal-fired power generation, urban sources of mercury (Hg) to the atmosphere, especially minor fugitive sources, are relatively poorly characterized. To identify urban sources of fugitive Hg emissions, passive air samplers (PASs) were deployed for periods of 4-6 weeks in the summer of 2016 at 145 sites across the Greater Toronto Area (GTA). PASs were also deployed along transects of increasing distance from five sites listed as Hg sources in the National Pollution Release Inventory (NPRI) within or near the GTA. Mean gaseous Hg concentrations in downtown Toronto (1.77 ± 0.28 ng m −3 ) are slightly, but significantly elevated relative to other parts of the GTA (1.42 ± 0.20 ng m −3 ). Similarly, concentrations at sites close to waste/recycling (1.61 ± 0.22 ng m −3 ) and hospitals/dental facilities (1.63 ± 0.21 ng m −3 ) are significantly higher than at sites presumably distant from potential sources (1.37 ± 0.20 ng m −3 ). Gaseous Hg concentrations are elevated near four of five NPRI source sites, but not near a wastewater treatment plant. Measured or predicted concentrations (using extrapolated transect relationships) close to known Hg sources do not correlate with reported NPRI emissions. For example, the Hg disposal company Aevitas Inc. has the lowest reported NPRI emissions (0.11 kg yr −1 ) among the five sources, but measured (12.3 ng m −3 ) and predicted (60.0 ng m −3 ) concentrations outside the facility are the highest. The PAS's ability to precisely and accurately discriminate small differences in gaseous Hg concentration (<0.2 ng m −3 ) at and near global background concentrations enables the mapping of the spatial concentration variability and the identification of fugitive Hg emission sources.

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“…If the adsorption amount of contaminants in the passive sampler only occurs through laminar diffusion, wind speed does not necessarily affect SR. However, in practical application, turbulence also affects adsorption; therefore, most passive samplers currently used are susceptible to the influence of wind speed and even wind direction [21,30]. During the 3rd measurement period, the average SR (0.077 ± 0.014 m 3 day −1 ) was slightly lower than that during the other two measurement periods, probably because the temperature was relatively low (on average 16.8 • C) while it was 27.1 • C and 24.5 • C during the 1st and 2nd periods, respectively.…”

Section: Sampling Ratementioning

confidence: 99%

“…Sulfur and the halogen elements significantly shorten the lifetime of the catalyst in the analytical instrument [18,19], whereas the addition of powdered Na 2 CO 3 substantially increases the catalyst's life [20]. Most previous studies found that the uptake rate by a Hg passive sampler was affected by meteorological factors including temperature and wind speed [8,21]; however, how they affected was different for each study. This study was initiated to develop and to apply a passive sampler for GEM, and the limitations of the passive sampler were identified.…”

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confidence: 99%

Application of the Passive Sampler Developed for Atmospheric Mercury and Its Limitation

et al. 2019

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In this study, a passive sampler for gaseous elemental mercury (GEM) was developed and applied to field monitoring. Three Radiello® diffusive bodies with gold-coated beads as Hg adsorbent were installed in an acrylic external shield. Hg uptake mass linearly increased as the deployment time increased until 8 weeks with an average gaseous Hg concentration of 2 ng m−3. The average of the experimental sampling rate (SR) was 0.083 m3 day−1 and showed a good correlation with theoretical SRs, indicating that a major adsorption mechanism was molecular diffusion. Nonetheless, the experimental SR was approximately 33% lower than the modeled SR, which could be associated with inefficient uptake of GEM in the sampler or uncertainty in constraining model parameters. It was shown that the experimental SR was statistically affected by temperature and wind speed but the calibration equation for the SR by meteorological variables should be obtained with a wider range of variables in further investigation. When the uptake rates were compared to the active Hg measurements, the correlation was not significant because the passive sampler was not sufficiently adept at detecting a small difference in the GEM concentration of from 1.8 to 2.0 ng m−3. However, the results for spatial Hg concentrations measured near cement plants in Korea suggest a possible application in field monitoring. Future research is needed to fully employ the developed passive sampler in quantitative assessment of Hg concentrations.

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The effects of meteorological parameters and diffusive barrier reuse on the sampling rate of a passive air sampler for gaseous mercury

Cited by 35 publications

References 30 publications

Global evaluation and calibration of a passive air sampler for gaseous mercury

Global evaluation and calibration of a passive air sampler for gaseous mercury

Identifying and evaluating urban mercury emission sources through passive sampler-based mapping of atmospheric concentrations

Application of the Passive Sampler Developed for Atmospheric Mercury and Its Limitation

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