Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models

Hélène Angot (1, 2) , Ashu Dastoor , Francesco de Simone (3) , Katarina Gårdfeldt , Christian N Gencarelli (3) , Ian M Hedgecock (3) , Sarka Langer , Olivier Magand (1, 2) , Michelle N Mastromonaco , Claus Nordstrøm , Katrine A Pfaffhuber , Nicola Pirrone , Andrei Ryjkov , Noelle E Selin , Henrik Skov , Shaojie Song , Francesca Sprovieri (3) , Alexandra Steffen , Kenjiro Toyota , Oleg Travnikov , Xin Yang , Aurélien Dommergue (1, 2)

1 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
2 OSUG - Observatoire des Sciences de l'Univers de Grenoble
3 IIA - Institute of Atmospheric Pollution Research

Mercury (Hg) is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions to deposition of Hg onto environmental surfaces, large uncertainties arise from our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission). Atmospheric Hg reactivity is exacerbated in high latitudes and there is still much to be learned from polar regions in terms of atmospheric processes. This paper provides a synthesis of the atmospheric Hg monitoring data available in recent years (2011–2015) in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. The cycle of atmospheric Hg in the Arctic and in Antarctica presents both similarities and differences. Coastal sites in the two regions are both influenced by springtime atmospheric Hg depletion events and by summertime snowpack re-emission and oceanic evasion of Hg. The cycle of atmospheric Hg differs between the two regions primarily because of their different geography. While Arctic sites are significantly influenced by northern hemispheric Hg emissions especially in winter, coastal Antarctic sites are significantly influenced by the reactivity observed on the East Antarctic ice sheet due to katabatic winds. Based on the comparison of multi-model simulations with observations, this paper discusses whether the processes that affect atmospheric Hg seasonality and interannual variability are appropriately represented in the models and identifies research gaps in our understanding of the atmospheric Hg cycling in high latitudes.

Domains: Biodiversity and Ecology; Other; Atmospheric and Oceanic Physics [physics.ao-ph]; Continental interfaces, environment

Hélène Angot, Ashu Dastoor, Francesco de Simone, Katarina Gårdfeldt, Christian N Gencarelli, et al.. Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models. Atmospheric Chemistry and Physics, 2016, 16 (16), pp.10735 - 10763. ⟨10.5194/acp-16-10735-2016⟩. ⟨hal-04383218⟩