1. TF HTAP Workshop, Potsdam, 2016 GMOS: Multi-model assessment of mercury pollution and processes Environment Canada Oleg Travnikov, Johannes Bieser, Ashu Dastoor, Carey Friedman, Ian Hedgecock, Volker Matthias, Andrew Ryzhkov, Noelle Selin, Francesco De Simone, Shaojie Song, Xin Yang

2. TF HTAP Workshop, Potsdam, 2016 GMOS Mercury Modelling Task Force Global Mercury Observation System (GMOS) Aircraft measurements Marine cruises RV Urania Ground-based sites Hg processes in the atmosphere Objectives: Evaluation of model performance using GMOS measurement data Multi-model study of Hg emissions and atmospheric processes Assessment of Hg intercontinental transport and future scenarios

3. TF HTAP Workshop, Potsdam, 2016 Participating chemical transport models (CTM): ModelScaleInstitution GLEMOSglobal/regionalEMEP/MSC-E ECHMERITglobalCNR-IIA (Italy) GEM-MACH-HgglobalEnvironment Canada GEOS-ChemglobalMIT (USA) CMAQ-HgregionalHZG (Germany) WRF-ChemregionalCNR-IIA (Italy) p-TOMCATglobalCambridge (UK) GMOS Mercury Modelling Task Force

4. TF HTAP Workshop, Potsdam, 2016 Participating chemical transport models (CTM): ModelScaleInstitution GLEMOSglobal/regionalEMEP/MSC-E ECHMERITglobalCNR-IIA (Italy) GEM-MACH-HgglobalEnvironment Canada GEOS-ChemglobalMIT (USA) CMAQ-HgregionalHZG (Germany) WRF-ChemregionalCNR-IIA (Italy) p-TOMCATglobalCambridge (UK) GMOS Mercury Modelling Task Force

5. TF HTAP Workshop, Potsdam, 2016 Measurement data Monitoring networks: GMOS (global) EMEP (Europe) NADP/MDN (USA/Canada) AMNet (USA) NAtChem (Canada) GMOS partners: Measurement data used for the analysis (2013) Location of monitoring sites GEM/TGM in air (31 sites) Wet deposition (135 sites) GEM, GOM, PBM in air (25 sites)

6. TF HTAP Workshop, Potsdam, 2016 Model evaluation vs. measurements GLEMOS GEOS-Chem GEM-MACH-HgECHMERIT Hg 0 air concentration (2013)

7. TF HTAP Workshop, Potsdam, 2016 Base run Simulation with the state-of-the-art model configuration (BASE) Model experiments Emission effects Model run with no anthropogenic emissions (NOANT) Modified speciation of Hg anthropogenic emissions (ANTSPEC) Unified natural/secondary emissions (COMNAT) Improved emissions base on inverse modelling (INVEMI) Atmospheric chemistry Model run with no atmospheric chemistry (NOCHEM) Simulation with Br oxidation chemistry with two different sets of Br air concentration (BRCHEM1 and BRCHEM2) Simulation with OH - initiated oxidation chemistry (OHCHEM) Simulation with O 3 - initiated oxidation chemistry (O3CHEM)

8. TF HTAP Workshop, Potsdam, 2016 Model experiments Source region apportionment Evaluation of Hg dispersion from 14 major source regions (Europe, North America, East Asia, South Asia etc.) Emission sectors apportionment Evaluation of Hg dispersion from 3 groups of emission sectors (stationary combustion, industrial sources, intentional use) Study setup Anthropogenic emissions: AMAP/UNEP inventory for 2010 Natural/legacy emissions: Model specific Target year: 2013

9. TF HTAP Workshop, Potsdam, 2016 Study of atmospheric chemistry Seasonal variation of Hg wet deposition Measurements ECHMERITGLEMOSGEM-MACH-HgGEOS-Chem Sites measuring Hg wet deposition 0 20 40 60 80 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Wet deposition, ng/m 2 /day 99 sites 0 10 20 30 40 50 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Wet deposition, ng/m 2 /day 14 sites

10. TF HTAP Workshop, Potsdam, 2016 0 20 40 60 80 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Wet deposition, ng/m 2 /day Hg 0 + Br (Br dataset I) 0 20 40 60 80 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Wet deposition, ng/m 2 /day Hg 0 + O 3 0 20 40 60 80 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Wet deposition, ng/m 2 /day Hg 0 + OH 0 20 40 60 80 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Wet deposition, ng/m 2 /day Hg 0 + Br (Br dataset II) Study of atmospheric chemistry Seasonal variation of wet deposition (North America) MeasurementsECHMERITGLEMOSGEM-MACH-HgGEOS-Chem 1 10 100 1000 -90-60-300306090 Latitude Br concentration, ppq Br concentration Br dataset I Br dataset II

11. TF HTAP Workshop, Potsdam, 2016 Simulated Hg deposition flux (2013) Mercury dispersion on a global scale Contribution of current emissions vs. legacy and natural sources 0 5 10 15 20 25 Average Hg deposition, g/km 2 /y Anthropogenic sources Legacy/natural sources

12. TF HTAP Workshop, Potsdam, 2016 Simulated Hg deposition flux (2013) Intercontinental transport Source apportionment of Hg anthropogenic deposition 0 2 4 6 8 10 12 Average Hg deposition, g/km 2 /y EuropeAfrica Middle East North America Central America South America South Asia East Asia Southeast Asia Australia and NZ CIS countries Antarctica Arctic Source/receptor regions

13. TF HTAP Workshop, Potsdam, 2016 Simulated Hg deposition flux (2013) Mercury atmospheric load to the ocean Hg anthropogenic deposition to aquatic regions (FAO) 0 1 2 3 4 5 Average Hg deposition, g/km 2 /y Source regions EuropeAfrica Middle East North America Central America South America South Asia East Asia Southeast Asia Australia and NZ CIS countries Antarctica Arctic Other regions

14. TF HTAP Workshop, Potsdam, 2016 Industrial sources Hg deposition from different emission sectors (2013) Stationary combustion Effect of Hg emission speciation Intentional use and product waste Speciation of global Hg emissions 0300600900 Intentional use & product waste Industrial sources Stationary combustion Hg emission, t/y Hg 0 HgII gas HgII part

15. TF HTAP Workshop, Potsdam, 2016 Future changes of mercury pollution Model evaluation of future emission scenarios (2035) Hg emission scenarios for 2035: ‘Current Policy’ scenario (CP 2035) Governmental policies and measures existing in 2010 have been adopted, including those that have not been fully implemented ‘New Policy’ scenario (NP 2035) Policy commitments announced by countries worldwide to reduce GHG emissions and phase out fossil-energy subsidies have been fully implemented ‘Maximum Feasible Reduction’ scenario (MFR 2035) Maximum possible Hg emission reductions that could be achieved if no other constraints have been taken into account Anthropogenic Hg emissions in 2010 and 2035 0.0 0.5 1.0 1.5 2.0 2.5 2010CP 2035 NP 2035 MFR 2035 Total emission, kt

16. TF HTAP Workshop, Potsdam, 2016 Source and receptor regions Model evaluation of future emission scenarios (2035) Future changes of mercury pollution 0 1 2 3 4 2010CP 2035 NP 2035 MFR 2035 Average Hg deposition, g/km 2 /y North America 0 2 4 6 8 10 2010CP 2035 NP 2035 MFR 2035 Average Hg deposition, g/km 2 /y Europe 0 5 10 15 20 25 2010CP 2035 NP 2035 MFR 2035 Average Hg deposition, g/km 2 /y South Asia 0 5 10 15 2010CP 2035 NP 2035 MFR 2035 Average Hg deposition, g/km 2 /y East Asia 0 1 2 2010CP 2035 NP 2035 MFR 2035 Average Hg deposition, g/km 2 /y Arctic

17. TF HTAP Workshop, Potsdam, 2016 Summary An ensemble of global models has been applied to study Hg emission, dispersion and cycling in the atmosphere Oxidation chemistry of Hg in the atmosphere is still not fully understood. There is possibility of multiple oxidation mechanisms Contribution of current anthropogenic emissions to deposition varies between 20% and 50% in different regions. Contribution of intercontinental transport is comparable or prevails over domestic sources in most regions except for South and East Asia Emissions speciation strongly affects the range of Hg dispersion and deposition. Hg speciation in available inventories contains significant uncertainties Future scenarios predict decrease of Hg deposition in the next 20 years except for South and East Asia where the ‘Current Policy’ can lead to deposition growth