A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow

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Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.

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Catégories consensuelles

aucune

Domaine

Signal candidat: aucuneSignal consensuel: aucune

Devis d'étude

Signal candidat: ObservationnelSignal consensuel: Observationnel

Genre

Signal candidat: EmpiriqueSignal consensuel: Empirique

Score de désaccord entre enseignants

0,380

Score d'incertitude au seuil

1,000

Statut de validation

machine_predicted_unvalidated · codex-gemma-dda1882f352a

Scores Codex et Gemma par catégorie

Scores machine (provisoires)

Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.

Écart entre enseignants

0,208 · la distance entre les deux têtes enseignantes sur ce seul travail

Statut de validation

score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découle

Résumé

Abstract. It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same form in the snow. Kinetic studies undertaken have demonstrated that bromine is the major oxidant depleting Hg in the atmosphere. Modeling results demonstrate that there is a significant deposition of Hg to Polar Regions as a result of AMDEs. Models have also shown that Hg is readily transported to the Arctic from source regions, at times during springtime when this environment is actively transforming Hg from the atmosphere to the snow and ice surfaces. The presence of significant amounts of methyl Hg in snow in the Arctic surrounding AMDEs is important because this species is the link between the environment and impacts to wildlife and humans. Further, much work on methylation and demethylation processes has occurred but these processes are not yet fully understood. Recent changes in the climate and sea ice cover in Polar Regions are likely to have strong effects on the cycling of Hg in this environment; however more research is needed to understand Hg processes in order to formulate meaningful predictions of these changes.

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La notice

Revue

Atmospheric chemistry and physics

Thématique

Mercury impact and mitigation studies

Domaine

Environmental Science

Établissements canadiens

University of OttawaMcGill UniversityUniversity of GuelphUniversité de MontréalCégep Marie-VictorinEnvironment and Climate Change Canada

Organismes subventionnaires

British Antarctic SurveyOffice of Polar ProgramsNational Science Foundation

Mots-clés

Mercury (programming language)SnowAtmosphere (unit)ArcticPolarEnvironmental chemistryThe arcticChemistryAtmospheric chemistryEnvironmental scienceAtmospheric sciencesMeteorologyOceanographyOzoneGeologyGeography

Résumé présent dans OpenAlex

oui

API

/api/v1/works/W2171756948