Global Mercury Modeling at Environment Canada. Ashu Dastoor &Didier Davignon. Air Quality Research Division Environment Canada

Transcription

1 Global Mercury Modeling at Environment Canada Ashu Dastoor &Didier Davignon Air Quality Research Division Environment Canada

2 Atmospheric Mercury Cycling in Environment Canada s Mercury Model - GRAHM Transport Within atmospheric meteorological model Resolution for HTAP simulations: 2 0 X2 0 horizontal, top 10 mb; 28 levels Gas-phase chemistry GEM RGM TPM O3, Halogens O3 from MOZART Halogens parameterized from satellite data & seasalt distribution Evaporation Gas/liquid exchange Heterogeneous Chemistry? Evaporation Cloud properties Met process GEM RGM TPM O 3, OH, HO 2, (Cl), SO 3, aerosols Transport Anthropogenic emissions GEM, RGM, TPM Pacyna yr 2000, 2188 Mg/yr Point sources Plume rise Area sources Terrestrial emissions 1600 Mg/yr (Mason & Sheu) Dry deposition GEM, RGM, TPM Polar & MBL regions Halogen chemistry Deposition evasion Wet deposition Met process Oceanic emissions Mg/yr Boundary Layer turbulent mixing Dry deposition GEM, RGM, TPM

3 TGM ng/m3 Inter-hemispheric gradient of TGM Observed and from GRAHM simulation S 60S 30S Eq. 30N 60N 90N Latitude Observed (left; Lamborg et al., 2002) and modeled (right)

4 Current Global Mercury Modeling at Environment Canada Source-receptor relationship experiments for HTAP model intercomparison study Intercontinental transport of mercury to the Arctic within IPY project Intercontinental Atmospheric Transport of Anthropogenic Pollutants to the Arctic (INCATPA) Modeling of halogen chemistry related fast cycling of mercury in MBL and Polar Regions and its impact on global mercury cycling. Development of GRAHM/GEM-MACH (multi-pollutant, air-quality modelling system with size segregated and chemically speciated representation of aerosols).

5 Schematic of the cycling of mercury in Polar Regions Steffen, 2007

6 Elemental mercury vapor concentration at Alert for the whole year Mercury concentration (ng/m 3 ) Mercury depletion Mercury reduction Mean mercury concentration in the Arctic Date (Julian Date)

7 Monthly averaged BrO concentrations (ng m-3) in the surface layer derived from GOME data for March and May 2003.

8 Simulated Surface Air GEM Concentrations (ng standard m -3 ) Winter Spring Summer Fall

9 Model simulated and measured concentrations of GEM (ng standard m-3) at Alert, Canada

10 Annual average deposition of mercury including halogen oxidation in boundary layer

11 Surface Mercury Fluxes (metric tons) within the Arctic Circle (North of 66.5 latitude) & interannual range for years ( net flux is positive downward) Jan-Feb Mar-May Jun-Aug Sept-Dec Annual Re-emission 10 (10) 164 ( ) 58 (57-59) 22 (22-23) 254 ( ) Deposition 36 (32-39) 244 ( ) 72 (68-74) 76 (75-77) 428 ( ) Accumulation Hg-Br: Ariya Accumulation Hg-Br: Donohoe 26 (22-29) 80 (77-83) 14 (12-16) 54 (54) 174 ( ) 27 (22-31) 65 (62-69) 16 (11-21) 55 (55) 164 ( ) Mass Balance at Barrow: March 25-April 7, 2003 (Brooks et al. 2006) Measured - deposition: 1.7 μgm-2, re-emission: μgm-2 & gain 0.7± 0.2 μgm-2 Simulated deposition:1.8 μgm-2, re-emission: 1.0 μgm-2 & gain 0.8 μgm-2

12 Task Force on Hemispheric Transport of Air Pollution Coordinated Modeling Studies Objective: to improve understanding of the intercontinental transport of air pollutants and to estimate the intercontinental flows of air pollutants. Two sets of experiments were developed: 1. Source-Receptor relationships 2. Passive tracer experiment

13 Source-Receptor Experiments: The Four Regions

14 Anthropogenic emissions, 2000 (total=2188mg/y) Canada 0.4% U.S.A. 5.0% Mexico 1.2% Europe 7.9% Russia 3.3% South & Central America 2.9% Brazil 1.5% India & neighbourgs 6.8% Japan & Koreas 10.3% Africa 6.5% China & neighbourgs 28.0% South Africa 11.7% EA 38% EU 11% SA 9% NA 7% Australia and Pacific Southest Asia 5.8% 1.7% West & Central Asia 7.1% Pacyna and Pacyna, 2006

15 Total Mercury deposition for 2001 using all emissions Total deposition from each of the four regions NA EU SA EA

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18 Objective: assess the level of POPs and Hg coming into Canadian Arctic from the Pan-Pacific Area Environment Canada Project Team Hayley Hung, Alexandra Steffen, Ashu Dastoor, Yi-Fan Li, Jianmin Ma, Tom Harner, Ed Sverko, Yushan Su, Sherry Bennett Collaboration Canada, China, Japan, Russia, USA, Vietnam

19 Coordinated measurements of POPs and Hg with researchers around the Pan-pacific area Build on existing air pollutant monitoring networks Couple measurements with computer models to describe the movement of POPs and Hg Assess climate change impact of these pollutants entering the Arctic.

20 INCATPA Site Map Mt. Changbai Wudalianchi Xuencheng Dillingham Fairbanks

21 Characteristics of LRT of mercury into the Arctic Model simulations air concentrations at the measurement sites and identification of episodes. Significance of mercury chemistry and dry and wet deposition processes in LRT. Relative contribution of direct emissions vs re-emissions from a source region Meteorological characteristics of the seasonal transport into and in the Arctic atmosphere in lower and middle troposphere. Role of halogen chemistry in LRT to the Arctic Impact of climate change on the LRT and deposition of mercury

22 Spring 2004 Experiment: Simultaneous Observations at Mt.Bachelor and Okinawa ( Jaffe et al. 2005) Okinawa Mauna Loa MBO Okinawa: Hg 0,RGM, PHg, CO, O 3, aerosols, etc. MBO: Total Hg 0, CO, O 3, aerosols, etc.

23 Simulated air concentrations of mercury(ng/m3) for April 23-25, 2004 at 500mb showing episode of Asian outflow of mercury observed at Mt. Bachelor, Oregon, USA by Jaffe et al. (Atmos. Environ. 2005) April 23, 06Z April 23, 18Z April 24, 06Z April 24, 18Z April 25, 06Z April 25, 18

24 Mercury concentrations observed by Daniel Jaffe et al. (2004) and modeled by GRAHM at Mt. Batchelor in central Oregon, USA The Asian emission simulation uses the scale on the right. April 25

25 DF FR Latitudinal and longitudinal trends of mercury flux ratios (FR) and anthropogenic flux (ΔF), and variation with lake area, for 49 sediment cores from Canada and northeastern USA FR = recent (post -1990) / pre-1850 fluxes and ΔF (μg m-2 y-1) = recent (post 1990) pre-1850 fluxes 7.0 Mercury FR vs Mercury FR vs latitude 6.0 Longitude arctic sub-arctic mid-latitude Mercury DF vs latitude arctic sub-arctic mid-latitude Latitude ( o N) Mercury DF vs lake size Lake area (km 2 ) Arctic Sub-arctic Mid-latitude Arctic Sub-arctic Mid-latitude Slide from Derek Muir-Mercury: Total Annual Deposition (representing ~mid-late 1990s) based on Sediment cores for 49 lakes Muir et al, SETAC Poster Nov. 2006

26 micro g /m2 ug/m2.y GRAHM Model Total Hg Annual Deposition for 49 lakes for Latitude Longitude Simulated deposition is in the observed range (0-30 ug/m2/yr) which suggests that the total deposition to the lakes is dominated by the direct atmospheric deposition. Stronger latitudinal and longitudinal gradients simulated by the model compared to sediment data imply the impact of the watershed characteristics.