Cavity ring-down spectroscopy sensor development for high-time-resolution measurements of gaseous elemental mercury in ambient air

Pierce, Ashley M.; Obrist, Daniel; Moosmüller, Hans; Faïn, Xavier; Moore, C. W.

doi:10.5194/amt-6-1477-2013

Cited by 17 publications

(29 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the instrument has a detection limit of ∼ 1 ng m −3 and therefore is preferred for industrial level studies but applicable under ambient Hg 0 concentrations (Holland, 2005). More recently, a high frequency (25 Hz) cavity ring-down spectroscopy (CRDS) sensor has been deployed for Hg 0 concentration measurement, but it has a higher detection limit (> 0.35 ng m −3 ) and suffers from the sensor's baseline drifting and interferences with O 3 (Faïn et al, 2010;Pierce et al, 2013). Another laser technique, the laser-induced fluorescence sensor, has been designed and successfully applied for up to 1 day of continuous measurement with improved detection limit (∼ 15 pg m −3 ) (Bauer et al, 2002(Bauer et al, , 2014.…”

Section: Advances In Hg 0 Flux Quantification Methodsmentioning

confidence: 99%

“…In saturated soil, Hg emission is suppressed because the soil pore space is filled with water, which hampers Hg mass transfer (Gillis and Miller, 2000b;Gustin and Stamenkovic, 2005). Pannu et al (2014) investigated Hg 0 flux over boreal soil by manipulating soil moisture, a maximum flux was observed at 60 % soil moisture (water filled pore space), whereas flux became inhibited at 80 %. Repeated rewetting experiments showed a smaller increase in emission, implying "volatizable" Hg 0 needs to be resupplied by means of reduction and dry deposition after a wetting event (Gustin and Stamenkovic, 2005;Song and Van Heyst, 2005;Eckley et al, 2011b).…”

Section: Air-soil Hg Exchangementioning

confidence: 99%

See 1 more Smart Citation

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

et al. 2016

View full text Add to dashboard Cite

Abstract. Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg 0 ) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg 0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg 0 . Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg 0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O 3 , radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling.We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg 0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg 0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg 0 flux observations in East Asia are comparatively larger in magnitude than the rest of the world, suggesting substantial re-emission of previously deposited mercury from anthropogenic sources. The Hg 0 exchange over pristine surfaces (e.g., background soil and water) and vegetation needs better constraints for global analyses of the atmospheric Hg budget. The existing knowledge gap and the associated research needs for future measurements and modeling efforts for the air-surface exchange of Hg 0 are discussed.

show abstract

Section: Advances In Hg 0 Flux Quantification Methodsmentioning

confidence: 99%

Section: Air-soil Hg Exchangementioning

confidence: 99%

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Faïn et al (2010) proposed that CRDS is capable of fast in situ measurements and reported a detection sensitivity of 0.1 ng m −3 with a 10 s time resolution. In more recent work, the same group appears to have acknowledged that, because of O 3 interference, in situ measurements of Hg(0) are not feasible using CRDS and that the sample needs to be stripped of ozone before introduction into the CRDS cavity (Pierce et al, 2013). Under these conditions they report a detection sensitivity of 0.35 ng m −3 with an integration time of 5 min.…”

Section: Comparison With Other Techniquesmentioning

confidence: 90%

“…However, it is clear that these systems require preconcentration and are not capable of fast in situ determination of Hg(0). Pierce et al (2013) provide a review of CRDS and other mercury sensors that might offer an alternative to CVAFS. Faïn et al (2010) proposed that CRDS is capable of fast in situ measurements and reported a detection sensitivity of 0.1 ng m −3 with a 10 s time resolution.…”

Section: Comparison With Other Techniquesmentioning

confidence: 99%

Deployment of a sequential two-photon laser-induced fluorescence sensor for the detection of gaseous elemental mercury at ambient levels: fast, specific, ultrasensitive detection with parts-per-quadrillion sensitivity

et al. 2014

View full text Add to dashboard Cite

Abstract. The operation of a laser-based sensor for gasphase elemental mercury, Hg(0), is described. It utilizes sequential two-photon laser excitation with detection of blueshifted laser-induced fluorescence (LIF) to provide a highly specific detection scheme that precludes detection of anything other than atomic mercury. It has high sensitivity, fast temporal resolution, and can be deployed for in situ measurements in the open atmosphere with essentially no perturbation of the environment. An ambient sample can also be pulled through a fluorescence cell, allowing for standard addition calibrations of the concentration. No type of preconcentration is required and there appears to be no significant interferences from other atmospheric constituents, including gas-phase oxidized mercury species. As a consequence, it is not necessary to remove oxidized mercury, commonly referred to as reactive gaseous mercury (RGM), from the air sample. The instrument has been deployed as part of an instrument intercomparison and compares well with conventional instrumentation that utilizes preconcentration on gold followed by analysis using cold-vapor atomic fluorescence spectroscopy (CVAFS). Currently, the achievable detection sensitivity is ∼ 15 pg m −3 (∼ 5 × 10 4 atoms cm −3 , ∼ 2 ppq) at a sampling rate of 0.1 Hz, i.e., averaging 100 shots with a 10 Hz laser system. Preliminary results are described for a 50 Hz instrument that utilizes a modified excitation sequence and has monitored ambient elemental mercury with an effective sampling rate of 10 Hz. Additional work is required to produce the precision necessary to perform eddy correlation measurements. Addition of a pyrolysis channel should allow for the measurement of total gaseous mercury (TGM) and hence RGM (by difference) with good sensitivity and time resolution.

show abstract

“…The first application of the EC technique to measure NEE of Hg 0 reported an emission flux of 849 ng m −2 h −1 over contaminated soils (85 mg Hg kg −1 dry soil) during a pilot campaign in Nevada, USA (Pierce et al, 2015). The EC system was based on a fast response (25 Hz), field-deployable pulsed cavity ring-down spectrometer (CRDS; Faïn et al, 2010;Pierce et al, 2013).…”

mentioning

confidence: 99%

Eddy covariance flux measurements of gaseous elemental mercury over a grassland

et al. 2020

View full text Add to dashboard Cite

Direct measurements of the net ecosystem exchange (NEE) of gaseous elemental mercury (Hg 0 ) are important to improve our understanding of global Hg cycling and, ultimately, human and wildlife Hg exposure. The lack of long-term, ecosystem-scale measurements causes large uncertainties in Hg 0 flux estimates. It currently remains unclear whether terrestrial ecosystems are net sinks or sources of atmospheric Hg 0 . Here, we show a detailed validation of direct Hg 0 flux measurements based on the eddy covariance technique (Eddy Mercury) using a Lumex RA-915 AM mercury monitor. The flux detection limit derived from a zero-flux experiment in the laboratory was 0.22 ng m −2 h −1 (maximum) with a 50 % cutoff at 0.074 ng m −2 h −1 . We present eddy covariance NEE measurements of Hg 0 over a low-Hg soil (41-75 ng Hg g −1 in the topsoil, referring to a depth of 0-10 cm), conducted in summer 2018 at a managed grassland at the Swiss FluxNet site in Chamau, Switzerland (CH-Cha). The statistical estimate of the Hg 0 flux detection limit under outdoor conditions at the site was 5.9 ng m −2 h −1 (50 % cutoff). We measured a net summertime emission over a period of 34 d with a median Hg 0 flux of 2.5 ng m −2 h −1 (with a −0.6 to 7.4 ng m −2 h −1 range between the 25th and 75th percentiles). We observed a distinct diel cycle with higher median daytime fluxes (8.4 ng m −2 h −1 ) than nighttime fluxes (1.0 ng m −2 h −1 ). Drought stress during the measurement campaign in summer 2018 induced partial stomata closure of vegetation. Partial stomata closure led to a midday depression in CO 2 uptake, which did not recover during the afternoon. The median CO 2 flux was only 24 % of the median CO 2 flux measured during the same period in the previous year (2017). We suggest that partial stomata closure also dampened Hg 0 uptake by vegetation, resulting in a NEE of Hg 0 that was dominated by soil emission. Finally, we provide suggestions to further improve the precision and handling of the "Eddy Mercury" system in order to assure its suitability for long-term NEE measurements of Hg 0 over natural background surfaces with low soil Hg concentrations (< 100 ng g −1 ). With these improvements, Eddy Mercury has the potential to be integrated into global networks of micrometeorological tower sites (FluxNet) and to provide the longterm observations on terrestrial atmosphere Hg 0 exchange necessary to validate regional and global mercury models.

show abstract

Cavity ring-down spectroscopy sensor development for high-time-resolution measurements of gaseous elemental mercury in ambient air

Cited by 17 publications

References 42 publications

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

Deployment of a sequential two-photon laser-induced fluorescence sensor for the detection of gaseous elemental mercury at ambient levels: fast, specific, ultrasensitive detection with parts-per-quadrillion sensitivity

Eddy covariance flux measurements of gaseous elemental mercury over a grassland

Contact Info

Product

Resources

About