Atmospheric particle evolution during a nighttime atmospheric mercury depletion event in sub-Arctic at Kuujjuarapik/Whapmagoostui, Québec, Canada

Gauchard, Pierre-Alexis; Ferrari, Christophe; Dommergue, Aurélien; Poissant, Laurier; Pilote, Martin; Guéhenneux, Gaëlle; Boutron, Claude F.; Baussand, Patrick

doi:10.1016/j.scitotenv.2004.05.022

Cited by 23 publications

(9 citation statements)

References 22 publications

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“…Engle et al, 2010;Peleg et al, 2015;Fu et al, 2016;Howard et al, 2017) and differ from the better-known polar AMDEs (Steffen et al, 2008, and reference within), as the former take place in the absence of sunlight and photolytic reactions. HYSPLIT trajectories showed no distinct source pattern for NAMDE nights, suggesting that the observed phenomena are due to local interactions and not the result of long-range transport of depleted air masses such as those observed by Gauchard et al (2005), Mastromonaco et al (2016) and Moore et al (2014).…”

Section: Nocturnal Atmospheric Mercury Depletion Eventsmentioning

confidence: 80%

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

Howard

Edwards

2018

Atmos. Chem. Phys.

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Abstract. Aerodynamic gradient measurements of the airsurface exchange of gaseous elemental mercury (GEM) were undertaken over a 40 ha alpine grassland in Australia's Snowy Mountains region across a 3-week period during the late austral summer. Bi-directional GEM fluxes were observed throughout the study, with overall mean value of 0.2 ± 14.5 ng m −2 h −1 and mean nocturnal fluxes of −1.5 ± 7.8 ng m −2 h −1 compared to diurnal fluxes of 1.8 ± 18.6 ng m −2 h −1 . Deposition velocities ranged from −2.2 to 2.9 cm s −1 , whilst ambient GEM concentrations throughout the study were 0.59 ± 0.10 ng m −3 . Cumulative GEM fluxes correlated well with 24 h running mean soil temperatures, and one precipitation event was shown to have a positive impact on diurnal emission fluxes. The underlying vegetation had largely senesced and showed little stomatal control on fluxes. Nocturnal atmospheric mercury depletion events (NAMDEs) were observed concomitant with O 3 depletion and dew formation under shallow, stable nocturnal boundary layers. A mass balance box model was able to reproduce ambient GEM concentration patterns during NAMDE and non-NAMDE nights without invoking chemical oxidation of GEM throughout the column, indicating a significant role of surface processes controlling deposition in these events. Surface deposition was enhanced under NAMDE nights, though uptake to dew likely represents less than one-fifth of this enhanced deposition. Instead, enhancement of the surface GEM gradient as a result of oxidation at the surface in the presence of dew is hypothesised to be responsible for a large portion of GEM depletion during these particular events. GEM emission pulses following nights with significant deposition provide evidence for the prompt recycling of 17 % of deposited mercury, with the remaining portion retained in surface sinks. The long-term impacts of any sinks are however likely to be minimal, as cumulative GEM flux across the study period was close to zero.

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Section: Nocturnal Atmospheric Mercury Depletion Eventsmentioning

confidence: 80%

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

Howard

Edwards

2018

Atmos. Chem. Phys.

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“…Local chemical reactions originating from an open water lead formed on the Hudson Bay, at a few kilometers from the sampling site, may have produced the AMDE A that triggered the enrichment of THg observed within the snowpack (Figure 2b). The origin of air mass for snow THg concentrations during AMDEs has also been assessed during international field campaigns organized at Svalbard [ Gauchard et al , 2005] and Whapmagoostui‐Kuujjuarapik [ Gauchard et al , 2004].…”

Section: Resultsmentioning

confidence: 99%

Fate of inorganic mercury and methyl mercury within the snow cover in the low arctic tundra on the shore of Hudson Bay (Québec, Canada)

et al. 2007

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[1] Snow samples were collected in the seasonal snow cover of the low arctic tundra (Whapmagoostui-Kuujjuarapik, Québec) during episodic atmospheric mercury depletion events (AMDEs) and in the snowmelt period, long after AMDEs had occurred. Total and methyl mercury analyses were done in order to investigate the critical factors influencing the fate of mercury once deposited in the snowpack. Following AMDEs, snow total mercury (THg) concentrations increased and were inversely proportional to the distance from Hudson Bay. The correlations between MeHg, sulfate (SO 4 2À ), and chlorine (Cl À ) snow concentrations implicated marine aerosols as a significant source of MeHg, independent of AMDEs. However, the newly deposited MeHg was unstable in the snow cover as 15-56% of the MeHg was demethylated or otherwise ''lost'' during the nighttime period. In contrast, during the snowmelt period, marine aerosols were not a significant source of MeHg. MeHg snow concentrations higher than 200 pg L À1 were observed when snow's heterotrophic plate counts, total suspended volatile solids, and total suspended solids were higher than 5.0 Â 10 5 CFU L À1 , 25 mg L À1 , and 90 mg L À1 , respectively. During the snowmelt, although the THg snow concentrations remained at 8-9 ng L À1 , the proportion of MeHg increased from 2.7 to 7.6%. This is the first report suggestive of the presence of mercury methylation activities within the snow cover of the low arctic tundra.Citation: Constant, P., L. Poissant, R. Villemur, E. Yumvihoze, and D. Lean (2007), Fate of inorganic mercury and methyl mercury within the snow cover in the low arctic tundra on the shore

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“…Since their discovery in 1995 at Alert in Nunavut, Canada (4), AMDEs have been observed in many polar regions (e.g., refs 7, 12-14), as well as in the sub-Arctic at Kuujjuarapik/ Whapmagoostui on the eastern coast of Hudson Bay in Quebec, Canada (15), and have been implicated as the source of elevated concentrations of total Hg (THg) found in surface snow in the Canadian Arctic and Hudson Bay region (6,7,16). With the use of atmospheric concentrations of pHg and RGM measured during AMDEs, it has been estimated that ∼150-300 tons of Hg(II) is deposited onto the Canadian Arctic archipelago each spring (7,17).…”

Section: Introductionmentioning

confidence: 99%

Rapid Reduction and Reemission of Mercury Deposited into Snowpacks during Atmospheric Mercury Depletion Events at Churchill, Manitoba, Canada

Kirk

Louis

Sharp

2006

Environ. Sci. Technol.

111

143

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Mercury (Hg) in some Arctic marine mammals has increased to levels that may be toxic to Northern peoples consuming them as traditional food. It has been suggested that sunlight-induced atmospheric reactions called springtime atmospheric Hg depletion events (AMDEs) result in the loading of -150-300 tons of Hg to the Canadian Arctic archipelago each spring and that AMDEs are the ultimate source of Hg to Arctic foodwebs. AMDEs result from the oxidation of gaseous elemental Hg0 (GEM) in Arctic atmospheres to reactive gaseous Hg (RGM) and particulate Hg (pHg), both of which fall out of the atmosphere to snowpacks. We studied the springtime cycling of Hg between air and snowpacks near Churchill, Manitoba, for 2 years to determine the net input of Hg to Hudson Bay from AMDEs. In 2004, we monitored atmospheric concentrations of GEM, pHg, and RGM while simultaneously measuring concentrations of total Hg (THg) in surface snow collected over the sea ice on Hudson Bay. During numerous springtime AMDEs, concentrations of THg in surface snow increased, often to over 60 ng/L, demonstrating that AMDEs resulted in deposition of oxidized Hg (Hg(II)) to snowpacks. However, immediatelyfollowing AMDEs, average concentrations of THg in snow declined drastically from between 67.8+/-7.7 ng/L during AMDEs to only 4.25+/-1.85 ng/L four or more days following them. In 2003, we measured THg in surface snow collected daily over the sea ice and total gaseous Hg (TGM) concentrations in the interstitial airspaces of snowpacks. When concentrations of THg in the surface snow decreased, concentrations of TGM in interstitial airspaces of the snowpack increased sharply from between approximately 1.4-3.4 ng/m(3) to between approximately 20-150 ng/m(3), suggesting thatthere was a reduction of deposited Hg(II) to GEM, which then diffused out of snowpacks. At snowmelt in both 2003 and 2004, average concentrations of THg in meltwater collected over Hudson Bay were only 4.04+/-2.01 ng/L. Using concentrations of THg in meltwater and snow water equivalent, we estimated a net springtime loading of only 2.1+/-1.7 mg/ha of Hg to Hudson Bay from AMDEs, indicating that only a small portion of the Hg(II) deposited during AMDEs enters Hudosn Bay each spring.

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Atmospheric particle evolution during a nighttime atmospheric mercury depletion event in sub-Arctic at Kuujjuarapik/Whapmagoostui, Québec, Canada

Cited by 23 publications

References 22 publications

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

Fate of inorganic mercury and methyl mercury within the snow cover in the low arctic tundra on the shore of Hudson Bay (Québec, Canada)

Rapid Reduction and Reemission of Mercury Deposited into Snowpacks during Atmospheric Mercury Depletion Events at Churchill, Manitoba, Canada

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