Feedback mechanisms between snow and atmospheric mercury: Results and observations from field campaigns on the Antarctic plateau

Spolaor, Andrea; Angot, Hélène; Roman, Marco; Dommergue, Aurélien; Scarchilli, Claudio; Vardè, Massimiliano; Guasta, Massimo Del; Pedeli, Xanthi; Varin, Cristiano; Sprovieri, Francesca; Magand, Olivier; Legrand, Michel; Barbante, Carlo; Cairns, Warren R. L.

doi:10.1016/j.chemosphere.2017.12.180

Cited by 18 publications

(22 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While used in several chemical transport models, O 3 -and OH-based chemical mechanisms are unlikely as pure gas-phase reactions since the formation of HgO is endothermic (Subir et al, 2011). The two-step Br-initiated scheme (R3-R10) can explain polar atmospheric mercury depletion events (Sprovieri et al, 2005;Steffen et al, 2008) and is likely the dominant Hg 0 oxidation pathway globally (Holmes et al, 2006;Horowitz et al, 2017;Ye et al, 2018). The recombination of Hg 0 and Br forms unstable Hg I Br, which either dissociates or is oxidized to Hg II by NO 2 , HO 2 , OH, Br, or BrO.…”

Section: Atmospheric Mercury Chemistrymentioning

confidence: 99%

Understanding mercury oxidation and air–snow exchange on the East Antarctic Plateau: a modeling study

et al. 2018

Self Cite

View full text Add to dashboard Cite

Abstract. Distinct diurnal and seasonal variations of mercury (Hg) have been observed in near-surface air at Concordia Station on the East Antarctic Plateau, but the processes controlling these characteristics are not well understood. Here, we use a box model to interpret the Hg0 (gaseous elemental mercury) measurements in thes year 2013. The model includes atmospheric Hg0 oxidation (by OH, O3, or bromine), surface snow HgII (oxidized mercury) reduction, and air–snow exchange, and is driven by meteorological fields from a regional climate model. The simulations suggest that a photochemically driven mercury diurnal cycle occurs at the air–snow interface in austral summer. The fast oxidation of Hg0 in summer may be provided by a two-step bromine-initiated scheme, which is favored by low temperature and high nitrogen oxides at Concordia. The summertime diurnal variations of Hg0 (peaking during daytime) may be confined within several tens of meters above the snow surface and affected by changing mixed layer depths. Snow re-emission of Hg0 is mainly driven by photoreduction of snow HgII in summer. Intermittent warming events and a hypothesized reduction of HgII occurring in snow in the dark may be important processes controlling the mercury variations in the non-summer period, although their relative importance is uncertain. The Br-initiated oxidation of Hg0 is expected to be slower at Summit Station in Greenland than at Concordia (due to their difference in temperature and levels of nitrogen oxides and ozone), which may contribute to the observed differences in the summertime diurnal variations of Hg0 between these two polar inland stations.

show abstract

Section: Atmospheric Mercury Chemistrymentioning

confidence: 99%

Understanding mercury oxidation and air–snow exchange on the East Antarctic Plateau: a modeling study

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…It has been shown that surface Arctic snow could lose up to 90 % of its total Hg content within 48 hours (Poulain et al, 2004). Similar, re-emission/loss rates of Hg from snow surface (35-50 %) and drifting snow (65-75 %) over 10.5 h have been suggested in chamber experiments (Sherman et al, 2010) while, in a study performed on the Antarctic Plateau, Spolaor et al 2018 suggest a loss of 90% of mercury in the upper snow layer within a few hours.…”

Section: Introductionmentioning

confidence: 62%

“…Each sample was weighed and the exact amount of HCl was added to reach a final concentration of 2 % (Planchon et al, 2004;Spolaor et al, 2018).…”

Section: Snow Mercury Analysismentioning

confidence: 99%

“…Mercury in its oxidized form can be deposited onto the snowpack, increasing Hg concentrations in the upper snow strata (Obrist et al, 2017). Once present in the snowpack, Hg is very labile, and it can be reduced back to elemental Hg (Hg(0)) and undergo dynamic exchange with the atmosphere above (Song et al, 2018;Spolaor et al, 2018;Steffen et al, 2002). The role of the snowpack is crucial in the mercury cycle in Polar Regions since it acts as both a sink (deposition, accumulation) and a source (re-emission).…”

Section: Introductionmentioning

confidence: 99%

“…Laboratory experiments have been carried out to understand light-induced processes regarding Hg and iodine (Durnford and Dastoor, 2011;Spolaor et al, 2013b). However few experiments have been carried out in the field, with the specific aim of understanding the diurnal dynamics of these elements in surface snow (Dommergue et al, 2003b;Ferrari et al, 2005;Spolaor et al, 2018). The unique high-temporal resolution experiments presented, aim to improve our understanding of the behaviour of these elements in the upper snow layers (0-3 cm) under different light and atmospheric conditions to investigate their short-term (diurnal) variation.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Diurnal cycle of iodine and mercury concentrations in Svalbard surface snow

Spolaor¹,

Barbaro²,

Cappelletti³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

<p><strong>Abstract.</strong> Sunlit snow is highly photochemically active and plays an important role in the exchange of gas-phase species between the cryosphere to the atmosphere. Here, we investigate the behaviour of two selected species in surface snow: mercury (Hg) and iodine (I). Hg can deposit year-round and accumulate in the snowpack. However, photo-induced re-emission of gas phase Hg from the surface has been widely reported. Iodine is active in atmosphere new particle formation, especially in the marine boundary layer, and in the destruction of atmospheric ozone. It can also undergo photochemical re-emission. Although previous studies indicate possible post-depositional processes, little is known about the diurnal behaviour of these two species and their interaction in surface snow. The mechanisms are still poorly constrained and no field experiments have been performed in different seasons to investigate the magnitude of re-emission processes. Three high temporal resolution (hourly samples) 3 days long sampling campaign were carried out near Ny-&#197;lesund (Svalbard) to study the behaviour of mercury and iodine in surface snow under different sunlight and environmental conditions (24&#8201;h-darkness, 24&#8201;h-sunlight and day/night cycles). Our results indicate a clearly different behaviour of Hg and I in surface snow during the different campaign. The day/night experiments demonstrate the existence of a diurnal cycle in surface snow for Hg and iodine, indicating that these species are indeed influenced by the daily solar radiation cycle. Differently bromine did not show any diurnal cycle. The diurnal cycle disappeared also for Hg and iodine during the 24&#8201;h-sunlight period and during 24&#8201;h-darkness experiments supporting the idea of the occurrence (absence) of a continuous recycling/exchange at the snow-air interface. These results demonstrate that this surface snow recycling is seasonally dependent, through sunlight. They also highlight the non-negligible role that snowpack emissions have on ambient air concentrations and potentially on iodine-induced atmospheric nucleation processes.</p>

show abstract

Mercury in precipitated and surface snow at Dome C and a first estimate of mercury depositional fluxes during the Austral summer on the high Antarctic plateau

Cairns

Turetta

Maffezzoli

et al. 2021

Atmospheric Environment

View full text Add to dashboard Cite

Feedback mechanisms between snow and atmospheric mercury: Results and observations from field campaigns on the Antarctic plateau

Cited by 18 publications

References 48 publications

Understanding mercury oxidation and air–snow exchange on the East Antarctic Plateau: a modeling study

Understanding mercury oxidation and air–snow exchange on the East Antarctic Plateau: a modeling study

Diurnal cycle of iodine and mercury concentrations in Svalbard surface snow

Mercury in precipitated and surface snow at Dome C and a first estimate of mercury depositional fluxes during the Austral summer on the high Antarctic plateau

Contact Info

Product

Resources

About