CNR – Institute of Atmospheric Pollution Research, Rende, Italy Climate Change and Future Scenarios in the Arctic Region Venice International

CNR – Institute of Atmospheric Pollution Research, Rende, Italy

http://www.iia.cnr.it

Climate Change and Future Scenarios in the Arctic Region

Venice International University, Isola di San Servolo

11-12 December 2014

The Polar Mercury Cycle in a changing climate

Ian M. Hedgecock1 and Nicola Pirrone2

[email protected] CNR – Institute of Atmospheric Pollution Research, Rende, Italy2 CNR – Institute of Atmospheric Pollution Research, Area della Ricerca di Roma 1, Monterotondo, Rome, Italy

mailto:[email protected]

Recent Progress towards limiting Mercury in the Environment



Hg Species in the EnvironmentElemental Mercury, Hg0

Unreactive, not very soluble, transported long distances, makes up most of the Hg in the atmosphere, and the major part of anthropogenic and almost all natural emissions

Oxidised Inorganic Mercury, HgII

The major component in mercury deposition fluxes, soluble, can be methylated in the water column, lasts a few days in the atmosphere

Methyl Mercury, MeHgXDeadly

Dimethyl Mercury Hg(CH3)2 – practically irrelevantCNR – Institute of Atmospheric Pollution Research, Rende, Italy


The impact of methylmercury on health



The fox on the leftlives on the coast and feeds on sea birds, and sometimes seal carcasses.The one on the right lives Inland and eats rodents and non-marine birds.

Bocharova et al.,Correlation between Feeding Ecology and Mercury Levels in Historical and Modern Arctic Foxes (Vulpes lagopus). PLoS ONE, 2013; 8 (5): e60879

The processes influencing Mercuryfluxes in the Arctic



• Atmospheric transport via the atmosphere of Hg0

• In-situ oxidation of Hg0 to HgII by Br, during the Bromine explosion

• Deposition of HgII, but also subsequent reduction followed by re-emission of Hg

• Methylation of HgII in (lakes, sediments, ocean)• Uptake by biota and subsequent bio-magnification

through the food web

All of which are likely to influenced by climate change

The chemistry behind the Bromine explosion is complex



Bromine is derived from sea-salt present both in sea-ice and because sea-salt aerosol deposits on the snow. Acidification of the snow (nitrate), solar radiation and wind blowing through the snow layers release Br compounds to the atmosphere.Pratt et al., Photochemical production of molecular bromine in Arctic surface snowpacks, Nature Geoscience 6, 351–356 (2013)

Recent studies show that it isn’t that simple



Cloud plumes from cracks of open water in the Arctic sea ice cover. Image credit: University of Hamburg, Germany

The age and salinity of sea-ice• The chemistry behind the Bromine explosion is influenced by, temperature,

solar radiation and salinity• Perennial sea-ice is less saline and less prone to form leads than seasonal

sea-ice• The boundary layer over ice is often low, hence the quantity of Hg available

to be oxidised is limited• When leads form they produce significant convection and therefore act to

pump Hg down from higher in the troposphere than when they are not present.

• The increased salinity of seasonal ice rather than perennial ice can lead to increased Bromine production especially during cold spells

Nghiem, S. V., et al. (2012), Field and satellite observations of the formation and distribution of Arctic atmospheric bromine above a rejuvenated sea ice cover, J. Geophys. Res., 117, D00S05Moore et al., (2014), Covective forcing if mercury and ozone in the Arctic boundary layer induced by leads in sea ice, Nature, 506, 81–84CNR – Institute of Atmospheric Pollution Research, Rende, Italy


And Chlorine tooScientists studying the atmosphere above Barrow, Alaska, have discovered unprecedented levels of molecular chlorine in the air, a new study reports.

“We don’t really know the mechanism. It’s a mystery to us right now,” Huey said. “But the sea ice is changing dramatically, so we’re in a time where we have absolutely no predictive power over what’s going to happen to this chemistry. We’re really in the dark about the chlorine.”

Researcher Jin Liao checks the instrumentation in Barrow, Alaska, during a research trip to measure molecular chlorine in the atmosphere. (Photo: Georgia Institute of Technology)Jin Liao et al., (2014) High levels of molecular chlorine in the Arctic atmosphere, Nature Geoscience 7, 91–94CNR – Institute of Atmospheric Pollution Research, Rende, Italy


Rivers



A recent study suggests that riverine input of Hg to the Arctic is significantly higher than once thought, and that input from rivers is twice that from the atmosphere.Which rivers is a good question as another study has shown that the burbot fish in two Russian rivers, the Lena and the Mezen, are safe to eat. Leandro et al., (2013), Low and Declining Mercury in Arctic Russian Rivers, ES&T, 48, 747-752

From Fisher et al., (2012), Riverine source of Arctic Ocean mercury inferred from atmospheric observations, Nature Geoscience 5, 499–504

And the less known unknownsWhile the impact of changing sea ice age and coverage are being studied and becoming better understood, the impact of riverine inputs is less well studied.

However as pointed out in a review by Stern et al., a number of consequences of climate change really are unquantifiable:

Permafrost melting – mercury release, more microbial activity?Ocean stratification – more oligotrophic waters increasing the rate of Hg methylation in the ocean?

Animal behaviour and animal feeding habits are likely to change, will they be more or less exposed to Hg contamination?

Stern et al., (2012), How does climate change influence arctic mercury? STOTEN, 414, 22–42CNR – Institute of Atmospheric Pollution Research, Rende, Italy


Further detailsThe Global Mercury Observation System www.gmos.eu

http://www.cnrmerc.org/ National Reference Centre for Mercury (CNRM)

Thank you

Documents

CNR – Institute of Atmospheric Pollution Research, Rende, Italy Climate Change and Future Scenarios in the Arctic Region Venice International