Articles | Volume 17, issue 3
Atmos. Chem. Phys., 17, 1881–1899, 2017

Special issue: Global Mercury Observation System – Atmosphere...

Atmos. Chem. Phys., 17, 1881–1899, 2017

Research article 08 Feb 2017

Research article | 08 Feb 2017

Particulate-phase mercury emissions from biomass burning and impact on resulting deposition: a modelling assessment

Francesco De Simone1, Paulo Artaxo2, Mariantonia Bencardino1, Sergio Cinnirella1, Francesco Carbone1, Francesco D'Amore1, Aurélien Dommergue3, Xin Bin Feng4, Christian N. Gencarelli1, Ian M. Hedgecock1, Matthew S. Landis5, Francesca Sprovieri1, Noriuki Suzuki6, Ingvar Wängberg7, and Nicola Pirrone8 Francesco De Simone et al.
  • 1CNR-Institute of Atmospheric Pollution Research, Division of Rende, UNICAL-Polifunzionale, 87036 Rende, Italy
  • 2University of Sao Paulo, Sao Paulo, Brazil
  • 3Univ. Grenoble Alpes, CNRS, IRD, IGE, Grenoble, France
  • 4Institute of Geochemistry, State Key Laboratory of Environmental Geochemistry, Chinese Academy of Sciences, Guiyang, China
  • 5Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC, USA
  • 6National Institute for Environmental Studies (NIES), Ministry of Environment, Okinawa, Japan
  • 7IVL, Swedish Environmental Research Inst. Ltd., Göteborg, Sweden
  • 8CNR-Institute of Atmospheric Pollution Research, Area della Ricerca di Roma 1, Via Salaria km 29 300, Monterotondo, 00015 Rome, Italy

Abstract. Mercury (Hg) emissions from biomass burning (BB) are an important source of atmospheric Hg and a major factor driving the interannual variation of Hg concentrations in the troposphere. The greatest fraction of Hg from BB is released in the form of elemental Hg (Hg0(g)). However, little is known about the fraction of Hg bound to particulate matter (HgP) released from BB, and the factors controlling this fraction are also uncertain. In light of the aims of the Minamata Convention to reduce intentional Hg use and emissions from anthropogenic activities, the relative importance of Hg emissions from BB will have an increasing impact on Hg deposition fluxes. Hg speciation is one of the most important factors determining the redistribution of Hg in the atmosphere and the geographical distribution of Hg deposition. Using the latest version of the Global Fire Emissions Database (GFEDv4.1s) and the global Hg chemistry transport model, ECHMERIT, the impact of Hg speciation in BB emissions, and the factors which influence speciation, on Hg deposition have been investigated for the year 2013. The role of other uncertainties related to physical and chemical atmospheric processes involving Hg and the influence of model parametrisations were also investigated, since their interactions with Hg speciation are complex. The comparison with atmospheric HgP concentrations observed at two remote sites, Amsterdam Island (AMD) and Manaus (MAN), in the Amazon showed a significant improvement when considering a fraction of HgP from BB. The set of sensitivity runs also showed how the quantity and geographical distribution of HgP emitted from BB has a limited impact on a global scale, although the inclusion of increasing fractions HgP does limit Hg0(g) availability to the global atmospheric pool. This reduces the fraction of Hg from BB which deposits to the world's oceans from 71 to 62 %. The impact locally is, however, significant on northern boreal and tropical forests, where fires are frequent, uncontrolled and lead to notable Hg inputs to local ecosystems. In the light of ongoing climatic changes this effect could be potentially be exacerbated in the future.

Short summary
Biomass burning (BB) releases of Hg, usually considered to be Hg(0), are a significant global source of atmospheric Hg. However there is experimental evidence that a fraction of this Hg is bound to particulate matter, Hg(P). This modelling study shows how increasing fractions of Hg(P) reduce the availability of Hg to the global pool, raising Hg exposure for those regions characterized by high BB, with implications for the sub-Arctic and also rice-growing areas in South-East Asia.
Final-revised paper