Mercury dynamics in the Rocky Mountain, Colorado, Snowpack

Abstract. Gaseous Elemental Mercury (GEM) was monitored at the Niwot Ridge (NWT) long-term ecological research (LTER) site (Colorado, USA, 40° N) from interstitial air extracted from the snowpack at depths ranging from the snow surface to 10 cm above the soil. A highly dynamic cycling of mercury (Hg) in this mid-latitude snowpack was observed. Patterns were driven by both GEM production in surface snow and GEM destruction in the deeper snowpack layers. Thorough mixing and vertical transport processes were observed through the snowpack. GEM was photochemically produced near the snow-air interface leading to enhanced GEM levels in interstitial air of surface snow of up to 8 ng m−3. During low wind periods, GEM in surface snow layers remained significantly above ambient air levels at night as well, which may indicate a potential weak GEM production over night. Analysis of vertical GEM gradients in the snowpack show that surface GEM enhancements efficiently propagated down the snowpack, with a temporal lag in peak GEM levels observed with increasing depth. Downward diffusion was responsible for much of these patterns, although vertical advection also contributed to vertical redistribution. Destruction of GEM in the lower snowpack layers was attributed to dark oxidation of GEM. Analysis of vertical GEM/CO2 flux ratios indicated that this GEM destruction occurred in the snow and not in the underlying soil. The strong, diurnal patterns of photochemical GEM production at the surface ultimately lead to re-emission losses of deposited Hg back to the atmosphere. The NWT data show that highest of GEM production and emission occur shortly after fresh snowfall, indicating that fresh snow possibly resupplies photoreducible Hg to the snowpack.

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Mercury dynamics in the Rocky Mountain, Colorado, snowpack

Biogeosciences ◽

10.5194/bg-10-3793-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 3793-3807 ◽

Cited By ~ 12

Author(s):

X. Faïn ◽

D. Helmig ◽

J. Hueber ◽

D. Obrist ◽

M. W. Williams

Keyword(s):

Rocky Mountain ◽

Co2 Flux ◽

Elemental Mercury ◽

Ambient Air ◽

Transport Processes ◽

Gaseous Elemental Mercury ◽

Air Interface ◽

Surface Snow ◽

Long Term Ecological Research ◽

Interstitial Air

Abstract. Gaseous elemental mercury (GEM) was monitored at the Niwot Ridge (NWT) Long-Term Ecological Research (LTER) site (Colorado, USA, 40° N) from interstitial air extracted from the snowpack at depths ranging from the snow surface to 10 cm above the soil. A highly dynamic cycling of mercury (Hg) in this mid-latitude snowpack was observed. Patterns were driven by both GEM production in surface snow and GEM destruction in the deeper snowpack layers. Thorough mixing and vertical transport processes were observed through the snowpack. GEM was photochemically produced near the snow-air interface throughout the entire winter, leading to enhanced GEM levels in interstitial air of surface snow of up to 8 ng m−3. During low-wind periods, GEM in surface snow layers remained significantly above ambient air levels at night as well, which may indicate a potential weak GEM production overnight. Analyses of vertical GEM gradients in the snowpack show that surface GEM enhancements efficiently propagated down the snowpack, with a temporal lag in peak GEM levels observed with increasing depth. Downward diffusion was responsible for much of these patterns, although vertical advection also contributed to vertical redistribution. Destruction of GEM in the lower snowpack layers was attributed to dark oxidation of GEM. Analysis of vertical GEM / CO2 flux ratios indicated that this GEM destruction occurred in the snow and not in the underlying soil. The strong, diurnal patterns of photochemical GEM production at the surface ultimately lead to re-emission losses of deposited Hg back to the atmosphere. The NWT data show that highest GEM surface production and re-emissions occur shortly after fresh snowfall, which possibly resupplies photoreducible Hg to the snowpack, and that photochemical GEM reduction is not radiation-limited as it is strong even on cloudy days.

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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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A cavity ring-down spectroscopy sensor for measurements of gaseous elemental mercury – Part 1: Development for high time resolution measurements in ambient air

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-8995-2012 ◽

2012 ◽

Vol 5 (6) ◽

pp. 8995-9020

Author(s):

A. Pierce ◽

D. Obrist ◽

H. Moosmüller ◽

X. Faïn ◽

C. Moore

Keyword(s):

Time Resolution ◽

Frequency Conversion ◽

Elemental Mercury ◽

Ambient Air ◽

High Time ◽

High Time Resolution ◽

Concentration Data ◽

Cavity Ring Down Spectroscopy ◽

Gaseous Elemental Mercury ◽

Cavity Ring Down

Abstract. The ability to make high time resolution measurements of gaseous elemental mercury (GEM) concentrations in air is imperative for the understanding of mercury cycling. Here we describe further development and field implementation of a laboratory prototype pulsed cavity ring-down spectroscopy (CRDS) system for high time resolution, continuous and automated measurement of GEM concentrations in ambient air. In particular, we present use of an external, isotopically enriched Hg cell for automated wavelength locking and wavelength stabilization to maintain laser wavelength on the peak of GEM absorption line in ambient air. We further describe implementation of differential absorption measurements using a piezoelectric tuning element that allows for continuous accounting of system baseline extinction losses needed to calculate GEM absorption coefficients. Data acquisition systems and software programs were modified to acquire high-speed ring-down data at 50 Hz repetition rate as well as process and analyze data in real time. The system was installed in a mobile trailer, and inlet systems and temperature controls were designed to minimize effects of changes in ambient air temperature and ozone (O3) concentration. Data that identify technical challenges and interferences that occurred during measurements, including temperature fluctuations, interferences by ambient O3 and drifts in frequency conversion efficiencies are discussed. Successful development of a CRDS system capable of measuring ambient air GEM concentrations with high time resolution is based on minimizing these interferences.

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Evaluation of cation exchange membrane performance under exposure to high Hg0 and HgBr2 concentrations

Atmospheric Measurement Techniques ◽

10.5194/amt-12-1207-2019 ◽

2019 ◽

Vol 12 (2) ◽

pp. 1207-1217 ◽

Cited By ~ 7

Author(s):

Matthieu B. Miller ◽

Sarrah M. Dunham-Cheatham ◽

Mae Sexauer Gustin ◽

Grant C. Edwards

Keyword(s):

Cation Exchange ◽

High Efficiency ◽

Absolute Humidity ◽

Elemental Mercury ◽

Mercury Vapor ◽

Ambient Air ◽

Atmospheric Mercury ◽

Promising Alternative ◽

Gaseous Elemental Mercury ◽

High Concentrations

Abstract. Reactive mercury (RM), the sum of both gaseous oxidized Hg and particulate bound Hg, is an important component of the global atmospheric mercury cycle, but measurement currently depends on uncalibrated operationally defined methods with large uncertainty and demonstrated interferences and artifacts. Cation exchange membranes (CEMs) provide a promising alternative methodology for quantification of RM, but method validation and improvements are ongoing. For the CEM material to be reliable, uptake of gaseous elemental mercury (GEM) must be negligible under all conditions and RM compounds must be captured and retained with high efficiency. In this study, the performance of CEM material under exposure to high concentrations of GEM (1.43×106 to 1.85×106 pg m−3) and reactive gaseous mercury bromide (HgBr2 ∼5000 pg m−3) was explored using a custom-built mercury vapor permeation system. Quantification of total permeated Hg was measured via pyrolysis at 600 ∘C and detection using a Tekran® 2537A. Permeation tests were conducted over 24 to 72 h in clean laboratory air, with absolute humidity levels ranging from 0.1 to 10 g m−3 water vapor. GEM uptake by the CEM material averaged no more than 0.004 % of total exposure for all test conditions, which equates to a non-detectable GEM artifact for typical ambient air sample concentrations. Recovery of HgBr2 on CEM filters was on average 127 % compared to calculated total permeated HgBr2 based on the downstream Tekran® 2537A data. The low HgBr2 breakthrough on the downstream CEMs (< 1 %) suggests that the elevated recoveries are more likely related to suboptimal pyrolyzer conditions or inefficient collection on the Tekran® 2537A gold traps.

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Measurements of atmospheric gaseous elemental mercury (GEM) and GEM fluxes in the seas of Southeast Asia in October-December 2019

10.5194/egusphere-egu2020-12394 ◽

2020 ◽

Author(s):

Viktor Kalinchuk ◽

Evgeny Lopatnikov ◽

Anatoly Astakhov ◽

Maksim Ivanov ◽

Renat Shakirov ◽

...

Keyword(s):

South China Sea ◽

Sea Of Japan ◽

South China ◽

Elemental Mercury ◽

Ambient Air ◽

The South China Sea ◽

The Sea Of Japan ◽

The South ◽

Gaseous Elemental Mercury ◽

China Sea

Measurements of gaseous elemental mercury (GEM) in the marine boundary layer (MBL) and GEM evasion fluxes were carried out during the Russian-Vietnam cruise conducted from the Sea of Japan to the South China Sea from October 25 to December 7, 2019. All GEM measurements were performed using two RA-915M mercury analysers (Lumex LLC, Russia). Atmospheric GEM concentrations were measured at two levels (about 2 m and 20 m above the sea surface) with a time resolution of 30 minutes. GEM fluxes were measured in the South China Sea using a dynamic flux chamber.GEM concentrations ranged between 0.56 ng/m3 and 25.47 ng/m3, and between 0.39 ng/m3 and 23.95 ng/m3 with medians of 1.38 ng/m3 and 1.45 ng/m3 for 2 m and 20 m measurements, respectively. GEM concentrations were significantly affected by air transport of GEM. Concentration Weighted Trajectory (CWT) analysis showed several source regions potentially influencing GEM concentrations in the ambient air during the cruise: the south of the South China Sea, Vietnam, the southeastern China, the south of Japan and the Korean peninsula. Maximum concentrations (up to 25 ng/m3) were registered in Haiphong (Vietnam).Hg(0) fluxes measured at 7 stations in the South China Sea ranged from 1.1 ng/m2/h to 2.5 ng/m2/h, with median value of 2.07 ng/m2/h. These values were 1,5 times higher than those that were measured by the same method in the Sea of Japan and the Sea of Okhotsk a month earlier.This work was supported by the Russian Science Foundation (RSF) (Project &#8470; 19-77-10011).

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Eddy covariance flux measurements of gaseous elemental mercury over a grassland

Atmospheric Measurement Techniques ◽

10.5194/amt-13-2057-2020 ◽

2020 ◽

Vol 13 (4) ◽

pp. 2057-2074 ◽

Cited By ~ 2

Author(s):

Stefan Osterwalder ◽

Werner Eugster ◽

Iris Feigenwinter ◽

Martin Jiskra

Keyword(s):

Detection Limit ◽

Eddy Covariance ◽

Co2 Flux ◽

Elemental Mercury ◽

Terrestrial Ecosystems ◽

Co2 Uptake ◽

Global Networks ◽

Gaseous Elemental Mercury ◽

Flux Measurements

Abstract. Direct measurements of the net ecosystem exchange (NEE) of gaseous elemental mercury (Hg0) 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 Hg0 flux estimates. It currently remains unclear whether terrestrial ecosystems are net sinks or sources of atmospheric Hg0. Here, we show a detailed validation of direct Hg0 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 Hg0 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 Hg0 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 Hg0 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 CO2 uptake, which did not recover during the afternoon. The median CO2 flux was only 24 % of the median CO2 flux measured during the same period in the previous year (2017). We suggest that partial stomata closure also dampened Hg0 uptake by vegetation, resulting in a NEE of Hg0 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 Hg0 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 long-term observations on terrestrial atmosphere Hg0 exchange necessary to validate regional and global mercury models.

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Performance of a new diffusive sampler for Hg0 determination in the troposphere

Environmental Chemistry ◽

10.1071/en06082 ◽

2007 ◽

Vol 4 (2) ◽

pp. 75 ◽

Cited By ~ 20

Author(s):

Henrik Skov ◽

Britt T. Sørensen ◽

Matthew S. Landis ◽

Matthew S. Johnson ◽

Paolo Sacco ◽

...

Keyword(s):

Detection Limit ◽

Elemental Mercury ◽

Ambient Air ◽

Atmospheric Mercury ◽

Point Sources ◽

Gaseous Elemental Mercury ◽

Marine Predators ◽

Diffusive Sampler ◽

Ambient Concentrations ◽

Areas Of Interest

Environmental context. Mercury is of concern to both the public and to the scientific community because it is found at high levels in some marine predators, prompting the US EPA and others to make guidelines restricting the consumption of some species. Most mercury in the environment is emitted to the atmosphere, but it is not known how it is transferred from the atmosphere to the marine environment. Therefore, it is important to study the connection between emission of mercury, its transport and removal from the atmosphere. We have developed a new sampler that is inexpensive, easy to use and with a sufficiently high detection limit that it can be used to measure the low mercury concentrations in the atmosphere at a reasonable time resolution. Abstract. Mercury behaves uniquely in the atmosphere due to its volatility and long lifetime. The existing methods for measuring atmospheric mercury are either expensive or labour intensive. The present paper presents a new measurement technique, the diffusive sampler, that is portable, inexpensive, easy to use, and does not need a power supply. The sampler is sufficiently sensitive that it can measure mercury at low ambient levels with an exposure time of 1 to 3 days. The sampler is based on the Radiello diffusive sampler, which was used to collect volatile organic compounds. In the present paper, the method is validated under controlled laboratory conditions. The uptake rate of the Radiello diffusive sampler is determined using known concentrations of gaseous elemental mercury, and is measured as a function of wind speed, relative humidity and temperature. The Radiello sampler has a detection limit of 0.14 ng m–3 for 1 day of exposure and thus can be used to measure mercury concentrations at the low levels found in ambient air. The Radiello sampler is therefore useful for mapping concentrations close to sources and sinks, in addition to ambient concentrations. For example, the sampler can be used to describe the geographical extent of Arctic mercury depletion episodes where gaseous elemental mercury is removed and stays close to 0 ng m–3 for days, and it can be a powerful tool for mapping gradients around point sources and other areas of interest.

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Mercury in the snow and firn at Summit Station, Central Greenland, and implications for the study of past atmospheric mercury levels

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-3441-2008 ◽

2008 ◽

Vol 8 (13) ◽

pp. 3441-3457 ◽

Cited By ~ 45

Author(s):

X. Faïn ◽

C. P. Ferrari ◽

A. Dommergue ◽

M. Albert ◽

M. Battle ◽

...

Keyword(s):

Elemental Mercury ◽

Atmospheric Mercury ◽

Main Process ◽

Near Surface ◽

Gaseous Elemental Mercury ◽

Chemical Mechanisms ◽

The Past ◽

Diel Variations ◽

History Of ◽

Interstitial Air

Abstract. Gaseous Elemental Mercury (Hg° or GEM) was investigated at Summit Station, Greenland, in the interstitial air extracted from the perennial snowpack (firn) at depths ranging from the surface to 30 m, during summer 2005 and spring 2006. Photolytic production and destruction of Hg° were observed close to the snow surface during summer 2005 and spring 2006, and we observed dark oxidation of GEM up to 270 cm depth in June 2006. Photochemical transformation of gaseous elemental mercury resulted in diel variations in the concentrations of this gas in the near-surface interstitial air, but destruction of Hg° was predominant in June, and production was the main process in July. This seasonal evolution of the chemical mechanisms involving gaseous elemental mercury produces a signal that propagates downward through the firn air, but is unobservably small below 15 m in depth. As a consequence, multi-annual averaged records of GEM concentration should be well preserved in deep firn air at depths below 15 m, and available for the reconstruction of the past atmospheric history of GEM over the last decades.

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Evaluation of cation exchange membrane performance under exposure to high Hg0 and HgBr2 concentrations

10.5194/amt-2018-127 ◽

2018 ◽

Author(s):

Matthieu B. Miller ◽

Mae S. Gustin ◽

Sarrah M. Dunham-Cheatham ◽

Grant C. Edwards

Keyword(s):

Cation Exchange ◽

High Efficiency ◽

Collection Efficiency ◽

Absolute Humidity ◽

Elemental Mercury ◽

Ambient Air ◽

Atmospheric Mercury ◽

Promising Alternative ◽

Gaseous Elemental Mercury ◽

Mercury Uptake

Abstract. Reactive mercury (RM) is an important component of the global atmospheric mercury cycle, but measurement currently depends on un-calibrated, operationally defined methods with large uncertainty and demonstrated interferences and artifacts. Cation exchange membranes (CEM) provide a promising alternative methodology for quantification of RM, but method validation and improvement are ongoing. For the CEM material to be reliable, uptake of gaseous elemental mercury (GEM) must be negligible for all conditions, and RM compounds must be captured and retained with high efficiency. In this study the performance of CEM material under exposure to high concentrations of GEM (1.43 × 106–1.85 × 106 pg m−3) and reactive gaseous mercury bromide (HgBr2 ~ 5000 pg m−3) was explored, using a custom-built mercury vapor permeation system, with quantification of total permeated Hg accomplished via pyrolysis at 600 °C and detection using a Tekran® 2537A. Permeation tests were conducted for 24 to 72 hours in clean laboratory air, with absolute humidity levels ranging from 0.1–10 g m−3 water vapor. Gaseous elemental mercury uptake by the CEM material averaged no more than 0.004 % of total exposure for all test conditions, which equates to a non-detectable GEM artifact for typical ambient air sample concentrations. Recovery of HgBr2 on CEM filters was > 100 % compared to calculated total permeated HgBr2, suggesting incomplete thermal decomposition at the pyrolyzer, as the CEM material collected HgBr2 with less than 1 % downstream breakthrough on average, implying a high collection efficiency.

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Studies of mercury species in the atomosphere in downtown Toronto

10.32920/ryerson.14649438 ◽

2021 ◽

Author(s):

Xinjie Song

Keyword(s):

Meteorological Parameters ◽

Inorganic Mercury ◽

Elemental Mercury ◽

Ambient Air ◽

Temporal Variations ◽

Anthropogenic Sources ◽

Mercury Species ◽

Gaseous Elemental Mercury ◽

Reactive Gaseous Mercury ◽

Mean Concentration

This study had been carried out in downtown Toronto from December 2003 to November 2004. Gaseous elemental mercury (GEM), reactive gaseous mercury (RGM, also called gaseous oxidized inorganic mercury, GOIM) and mercury associated with particles having size (PM<2.5) were simultaneously measured using Tekran mercury speciation unit. Mean concentration, standard deviation and distribution of GEM, PM<2.5 and RGM were 4.52 +/- 3.13 ng m⁻³ (98.7%), 21.51 +/- 16.35 pg m⁻³ (0.5%) and 14.19 +/- 13.24 pg m⁻³ (0.3%), respectively. Local and regional anthropogenic sources are believed to contribute [to] the elevated value and high temporal variations. Overall, the mercury species concentrations are lower in winter than in the other three seasons. Nighttime GEM, PM<2.5 and RGM concentrations are higher than those of daytime. Correlation analysis was conducted between each mercury species and the meteorological parameters (i.e., surface ambient air temperature, relative humidity, wind direction), as well as among the mercury species in this study.

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Mercury dynamics in the Rocky Mountain, Colorado, Snowpack