Current and future levels of mercury atmospheric pollution on a global scale

Abstract

Abstract. An assessment of current and future emissions, air concentrations, and atmospheric deposition of mercury worldwide is presented on the basis of results obtained during the performance of the EU GMOS (Global Mercury Observation System) project. Emission estimates for mercury were prepared with the main goal of applying them in models to assess current (2013) and future (2035) air concentrations and atmospheric deposition of this contaminant. The combustion of fossil fuels (mainly coal) for energy and heat production in power plants and in industrial and residential boilers, as well as artisanal and small-scale gold mining, is one of the major anthropogenic sources of Hg emissions to the atmosphere at present. These sources account for about 37 and 25 % of the total anthropogenic Hg emissions globally, estimated to be about 2000 t. Emissions in Asian countries, particularly in China and India, dominate the total emissions of Hg. The current estimates of mercury emissions from natural processes (primary mercury emissions and re-emissions), including mercury depletion events, were estimated to be 5207 t year−1, which represents nearly 70 % of the global mercury emission budget. Oceans are the most important sources (36 %), followed by biomass burning (9 %). A comparison of the 2035 anthropogenic emissions estimated for three different scenarios with current anthropogenic emissions indicates a reduction of these emissions in 2035 up to 85 % for the best-case scenario. Two global chemical transport models (GLEMOS and ECHMERIT) have been used for the evaluation of future mercury pollution levels considering future emission scenarios. Projections of future changes in mercury deposition on a global scale simulated by these models for three anthropogenic emissions scenarios of 2035 indicate a decrease in up to 50 % deposition in the Northern Hemisphere and up to 35 % in Southern Hemisphere for the best-case scenario. The EU GMOS project has proved to be a very important research instrument for supporting the scientific justification for the Minamata Convention and monitoring of the implementation of targets of this convention, as well as the EU Mercury Strategy. This project provided the state of the art with regard to the development of the latest emission inventories for mercury, future emission scenarios, dispersion modelling of atmospheric mercury on a global and regional scale, and source–receptor techniques for mercury emission apportionment on a global scale.

Sensitivity model study of regional mercury dispersion in the atmosphere

“…The NOANT experiment is a hypothetical scenario, but it allows the contribution of anthropogenic emissions to total deposition, which is roughly two-thirds, not counting the fact that natural emissions from the oceans are in part previously deposited Hg from anthropogenic sources. A number of policy scenarios were used during the GMOS project to estimate future trends in the anthropogenic emission of Hg (Pacyna et al, 2016). Pacyna et al (2016) describe the results of modelling studies using these scenarios to assess Hg concentration and deposition fields, for present (2013) and future anthropogenic (2035) Hg emissions.…”

“…A number of policy scenarios were used during the GMOS project to estimate future trends in the anthropogenic emission of Hg (Pacyna et al, 2016). Pacyna et al (2016) describe the results of modelling studies using these scenarios to assess Hg concentration and deposition fields, for present (2013) and future anthropogenic (2035) Hg emissions.…”

“…Compared to the north of Europe, however, southern and eastern Europe still lack monitoring stations. Within GMOS global chemical transport models (CTMs) have been used to evaluate the intercontinental transport of anthropogenic Hg and analyse different future Hg emission scenarios (Pacyna et al, 2016), source-receptor relationships (Travnikov et al, 2010) and Hg cycles in the polar regions . Regionalscale models have been used for a closer study of the processes that occur in specific areas at much higher spatial resolution than the global CTMs Bieser et al, 2014).…”

A synthesis of research needs for improving the understanding of atmospheric mercury cycling

“…Existing emission inventories are thought to be relatively accurate for anthropogenic emission source categories such as energy and industrial sectors in the United States and Europe, but with large uncertainties for other anthropogenic sources, and even larger uncertainties for natural sources and re-emission estimation (Pacyna et al, 2016).…”

Airborne mercury species at the Råö background monitoring site in Sweden: distribution of mercury as an effect of long-range transport

“…Atmospheric mercury has both natural and anthropogenic sources and is believed to have increased by a factor of 3 or more since industrialisation (Lamborg et al, 2002). The principal manmade emission sources of mercury are artisanal and small-scale gold production, coal combustion, non-ferrous and other primary metal production as well as cement production (Pacyna et al, 2016). Re-emission of mercury to the atmosphere is caused by reduction of deposited oxidised mercury on sea and land surfaces and enhances distribution and atmospheric exposure of mercury to the environment.…”