Summary of Part B: Mercury

Transcription

1 Summary of Part B: Mercury Nicola Pirrone CNR Institute of Atmospheric Pollution Research Rome, Italy 6 th Meeting of the TF HTAP Mercure Brussels Center Louise, Brussels June 2010

2 B1 - Conceptual Overview (30 pages) Lead Author: Robert Mason Contributing Authors: Ian Hedgecock, Nicola Pirrone, Noriyuki Suzuki, Leonard Levin B2 Observations (57 pages) Lead Author: Ralf Ebinghaus Contributing Authors: Aurélien Dommergue, Dan Jaffe, Gerald J. Keeler, Hans Herbert Kock, Nicola Pirrone, David Schmeltz, Francesca Sprovieri B3 Emissions (24 pages) Lead Author: Nicola Pirrone Contributing Authors: Sergio Cinnirella, Xinbin Feng, Hans Friedli, Leonard Levin, Jozef Pacyna, Elisabeth G. Pacyna, David Streets, Kyrre Sundseth B4 - Global and Regional Modeling (50 pages) Lead Authors: Oleg Travnikov, Che-Jen Lin, Ashu Dastoor Contributing Authors: O. Russell Bullock, Ian M. Hedgecock, Christopher Holmes, Ilia Ilyin, Lyatt Jaeglé, Gerlinde Jung, Li Pan, Pruek Pongprueksa, Christian Seigneur, Henrik Skov B5 Impacts (39 pages) Lead Author: Elsie Sunderland Contributing Authors: Elizabeth Corbitt, Daniel Cossa, David Evers, Hans Friedli, David Krabbenhoft, Leonard Levin, Nicola Pirrone, Glenn Rice B6 Executive Summary (10 pages) Authors: Nicola Pirrone, Ian M. Hedgecock Part B = 210 pages

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7 The Mercury Cycle B1 - Conceptual Overview A: Major Ecosystem Inputs and Outputs of Mercury Evasion from Soil and Vegetation Wet Deposition and Dry Deposition of Gaseous and Particulate Hg Evasion Watershed Retention and Transport/Runoff of Hg and CH 3 Hg Bioaccumulation of CH 3 Hg Biota B: Major Aquatic Mercury Pathways CH 3 Hg(II) demethylation reduction Hg(II) evasion Hg(0) methylation oxidation Burial in Sediments diffusion resuspension sedimentation diffusion resuspension Source: Sunderland & Mason, 2007

8 Major Findings B1 - Conceptual Overview Mercury impact is not directly related to its atmospheric burden, which is mostly as Hg 0, which has a low deposition velocity and is relatively insoluble. Oxidized forms of Hg are removed from the atmosphere more readily. Given the long residence time of Hg 0 in the atmosphere, this is the major transport pathway for the global redistribution of Hg. Levels of MeHg in fish are used as the major environmental impact indicator of Hg contamination, and they respond both to changes in atmospheric Hg inputs and composition, and changes in environmental conditions in the atmosphere and in aquatic ecosystems. The response time to changes in atmospheric oxidized Hg (RGHg) input is most rapid, with the response to changes in Hg 0, and to other environmental variables being much slower. The current lack of understanding of a number of important processes in the environmental cycling of Hg between the earth's surface and the atmosphere, and the transformations which take place in the atmosphere, make it almost impossible to predict the changes that might occur due to climate change. Without detailed information from a monitoring network, it will be very difficult to estimate the changes that may occur and to make accurate predictions of future trends.

9 Recommendations B1 - Conceptual Overview Studies are needed on possible measures to reduce the global atmospheric Hg pool. Efforts to control the inputs of oxidized Hg will have more immediate benefit but long term reduction in the Hg 0 content of the atmosphere is also needed to achieve the required health and environmental thresholds. More studies of the mechanisms of exchange of atmospheric Hg with the aquatic environment are needed, and these fluxes need to be better quantified and constrained. Further studies of the atmospheric oxidation mechanisms of Hg 0 are needed as, in the absence of oxidized emissions; this is a critical process step between atmospheric Hg and its environmental impact.

10 B2 Measurements Worldwide Mercury Measurements

11 B2 Measurements Worldwide Mercury Measurements

12 Past Trends B2 Measurements Chemical analysis of lake sediments, ice cores and peat deposits from both hemispheres indicates about a threefold increase of mercury deposition since pre-industrial times from: Lindberg, S., Bullock, R., Ebinghaus, R., Engstrom, D., Feng, X., Fitzgerald, W., Pirrone, N., Prestbo, E. and Seigneur C. (2007) A Synthesis of Progress and Uncertainties in Attributing the Sources of Mercury in Deposition. Ambio, Vol. 36, No. 1, pp

13 Monitoring of More Recent Change B2 Measurements Asian mercury emissions are suggested to be rapidly increasing at least in the past decade In principal, an increase of the global atmospheric Hg pool should also be reflected in the background Hg concentration in ambient air. Regional differences, temporal trends and potential sources and source regions can be identified by monitoring networks.

14 Monitoring Network in the framework of MAMCS, MOE, MERCYMS B2 Measurements 1. Mallorca ( N, E); 2. Calabria (39 25 N, E); 3. Sicily (36 40 N, 15 l0 E); 4. Turkey ( N, E); 5. Israel (32 40 N, E); 6. Germany ( N, ); 7. Germany ( N, E); 8. Sweden ( N, ll E); 9. Sweden ( , E); 10.Ireland (53 20 N, 9 54 W)

15 B2 Measurements Source: Sprovieri et al. ACPD, 2010

16 Atmospheric and Air-Water Interface Studies since See special issue in: Atmospheric Environment 2001, 2003, 2005 Marine Chemistry 2007 Atmospheric Chemistry and Physics, B2 Measurements

17 B2 Measurements Source: Sprovieri et al. ACPD, 2010

18 B2 Measurements Source: Sprovieri et al. ACPD, 2010

19 Ḅ2 Measurements Spatial characteristics of atmospheric Hg in U.S Source: Sprovieri et al. ACPD, 2010

20 Spatial characteristics of atmospheric Hg in U.S. B2 Measurements Sites near point sources (urban areas and mines (< 50 km) Sites influenced by regional point sources (< 500 km) Hg 0 Range of Means (ng/m3) RGM Mean - Max (pg/m3) Hgp Mean - Max (pg/m3) Precip. [Hg T ] Mean - Max (ng/l) Background sites High altitude site (3 km) NA

21 CAMNet Alert B2 Measurements CAMNet active other CAMNet closed Little Fox Lake Fort Chipewyan Whistler Bratts Lake Reifel Island Esther Kuujjuarapik ELA Burnt Island Egbert Mingan St. Anicet Pt. Petre South Hampton Kejimkujik St. Andrews Source: Sprovieri et al. ACPD, 2010

22 B2 Measurements 11 CAMNet sites were analyzed for temporal trends ( ) decreasing trend for TGM at several rural sites was seen from 1995 to 2005 (-2.2 to -16.6%); changes are mostly driven by local or regional variations in Hg emissions; other sites reflect hemispherical global background concentrations of airborne mercury, where slight decreases or no statistically significant trend in TGM concentrations exist over the same time period.

23 B2 Measurements Source: Sprovieri et al. ACPD, 2010

24 B2 Measurements Current Global Hg-background Concentration In the Northern Hemisphere 1.5 to 1.7 ng m -3 In the Southern Hemisphere 1.1 to 1.3 ng m -3 Key Sources: Sprovieri, F., Pirrone, N., Ebinghaus, R., Kock, H., and Dommergue, A. (2010) Worldwide atmospheric mercury measurements: a review and synthesis of spatial and temporal trends. Atmos. Chem. Phys. Discuss., 10, , Lindberg, S., Bullock, R., Ebinghaus, R., Engstrom, D., Feng, X., Fitzgerald, W., Pirrone, N., Prestbo, E. and Seigneur C. (2007) A Synthesis of Progress and Uncertainties in Attributing the Sources of Mercury in Deposition. Ambio, Vol. 36, No. 1, pp

25 B2 Measurements Long-term monitoring at single background locations The question of trends

26 Long-Term Measurements at Mace Head from today B2 Measurements TGM (24 h av. ), Mace Head, Ireland, Since 2003 funded by: 0.0 Aug/ 95 Jan/ 96 Jul/ 96 Jan/ 97 Jul/ 97 Jan/ 98 Jul/ 98 Jan/ 99 Jul/ 99 Jan/ 00 Jul/ 00 Jan/ 01 Since 2003 funded by: Jun/ 01 Dec/ 01 Jun/ 02 Dec/ 02 Jun/ 03 Dec/ 03 Jun/ 04 Dec/ 04 Jun/ 05 Dec/ 05 Jun/ 06 Dec/ 06 May/ 07 Nov/ 07

27 TGM Conc. at Temperate and Polar Coasts B2 Measurements Alert Data: Schroeder, Steffen and co-worker; Mace Head Data: Ebinghaus, Kock and co-worker

28 Major Findings B2 Measurements Concentration data and trends Mercury concentration measurements in ambient air of documented and accepted quality are available since the mid 1970 and concentration data are available for both hemispheres. Long-term monitoring of atmospheric mercury with high time resolution has been started at Alert, Canada (January 1995) and Mace Head, Ireland (September 1995), followed by numerous other sites since then. Consensus exists about the current global Hg 0 background concentration with 1.5 to 1.7 ng m -3 in the Northern Hemisphere and 1.1 to 1.3 ng m -3 in the Southern Hemisphere (at sea level). Competing hypotheses on trends in atmospheric TGM levels in the global atmosphere exist for the time period mid 1970 to 2000

29 Major Findings B2 Measurements Over water measurements TGM measurements on board ships proved to provide valuable complementary information to measurements from the ground based monitoring network. All cruises show a pronounced concentration gradient between the hemispheres with a ratio NH/SH: 1.45 The inter-hemispherical gradient with 30% higher TGM concentrations in the northern hemisphere remained nearly constant since mid Open-ocean investigations have demonstrated the importance of air sea exchange in controlling the Hg concentration in the atmosphere. Most studies, have revealed a net flux of Hg 0 from the ocean into the atmosphere, based on the DGM saturation of the water phase.

30 Major Findings B2 Measurements Emission estimates and field observations Asian emissions are considered to be of global importance and are suggested to be rapidly increasing in the past decade. Experimental data show long-range transport across the Pacific and suggest a significant underestimate of Asian mercury emissions Potentially increased Asian emissions are neither reflected in the long-term measurement of TGM at Mace Head ( ), nor in the precipitation data of the North American MDN. The reason for this is not yet clear.

31 Major Findings B2 Measurements AMDEs and global cycling Atmospheric mercury depletion events (AMDEs) have been detected at numerous sites in the Arctic and Antarctic environment Atmospheric mercury depletion events (AMDEs) have recently also been detected at a non-polar station (Cape Point), the chemistry involved seems to be different We have limited understanding of the chemical cycling of mercury and other atmospheric components in remote regions with seasonally variable sea-ice coverage.

32 Recommendations B2 Measurements Observational networks The establishment of a coordinated global monitoring network is highly recommended. This should incorporate already existing long-termatmospheric mercury monitoring stations and a number of additional sites, especially in the Southern hemisphere Such a mercury network should be closely linked to existing sites with globally representative distribution and a long-term perspective, such as WMO GAW sites It should be ensured that this measurement network is strongly supported my regional and global modelling, for scenario analysis and to support decision making for protecting human and environmental health. The combination of intermittent shipboard and long-term ground measurements can provide information about the worldwide distribution and trend of atmospheric Hg. Occasional shipboard measurements should thus be a part of the global monitoring network for atmospheric Hg. More effort should be dedicated to Deposition Networks with large spatial coverage and long-term perspective

33 Recommendations B2 Measurements Atmospheric chemistry and source attribution We need a better understanding of the interplay of sources and removal processes since the spatial pattern of Hg concentrations in wet deposition has some aspects that cannot be fully reconciled. We need a better understanding which sites would respond most quickly to changes in emissions and which sites are independent of local or regional sources and predominantly influenced by the global pool We need more long-term data and spatial coverage to understand long-term changes in RGM and PM Intercontinental transport of mercury can be estimated from Hg/CO measurements at fixed stations however, more emphasis should be addressed to the question why results based on this approach differ significantly from emission estimates, i.e. the possible underestimation of anthropogenic sources, the possibility of large and presently unaccounted natural sources and erroneous speciation of anthropogenic emissions estimates

34 Recommendations B2 Measurements Polar regions Long term measurements of Hg 0 and other atmospheric Hg species in the Polar Regions are very limited and need to be increased. More research and investigation on possible reaction mechanisms and chemical kinetics of atmospheric mercury in Polar regions are required to successfully improve our understanding of chemicalphysical processes involved in the mercury cycle in order to assess the resulting net input into the polar biosphere.

35 Development of the GEO Task HE-09-02d B2 Measurements An important contribution to the future development of the GEO Task HE-09-02d will be provided by GMOS in addition to the contributions from other countries that act as Co-Leads and as Contributors. Status of Play: The European Commission just approved for funding the proposal Global Mercury Observation System GMOS with a total budget of about 9 M. GMOS Coordinator: Nicola Pirrone, CNR-IIA, Italy GMOS involves 24 partners from all over the world. GMOS will start in Nov and will end in 2015.

36 GMOS partnership B2 Measurements

37 GMOS Overarching Objectives B2 Measurements To establish a Global Observation System for Mercury able to provide ambient concentrations and deposition fluxes of mercury species around the world, by combining observations from permanent ground-based stations, and from oceanographic and tropospheric measurement campaigns. To validate regional and global scale atmospheric mercury modelling systems able to predict the temporal variations and spatial distributions of ambient concentrations of atmospheric mercury, and Hg fluxes to and from terrestrial and aquatic receptors. To evaluate and identify source-receptor relationships at country scale and their temporal trends for current and projected scenarios of mercury emissions from anthropogenic and natural sources. To develop interoperable tools to allow the sharing of observational and models output data produced by GMOS, for the purposes of research and policy development and implementation as well as at enabling societal benefits of Earth observations, including advances in scientific understanding in the nine Societal Benefit Areas (SBA) established in GEOSS.

38 B2 Measurements GMOS Ground-Based Observation System

39 GMOS Oceanographic Program B2 Measurements

40 GMOS Aircraft-Based Program B2 Measurements

41 Global Anthropogenic Emissions of Mercury (Mg/yr) B3 Emissions Stationary combustion Waste disposal VCM production Intentional use Artisanal gold prod. Cremation Pig iron and steel production Non-ferrous metal production Mercury production Commercial gold production Cement production Caustic soda production Other Coal bed fires A A B C D E F G H A A B C D E F G H A Pirrone et al., 1996; B Pacyna et al., 2003; C Pacyna et al., 2006; D Streets et al., 2009b E Pirrone et al., 2008; F Pacyna et al., 2009; G Pirrone et al., 2009; H Pirrone et al., 2010

42 Global Anthropogenic Emissions of Mercury (Mg/yr) B3 Emissions Total (Anthropogenic) A A B C D E F G H A Pirrone et al., 1996; B Pacyna et al., 2003; C Pacyna et al., 2006; D Streets et al., 2009b E Pirrone et al., 2008; F Pacyna et al., 2009; G Pirrone et al., 2009; H Pirrone et al., 2010

43 B3 Emissions Global Anthropogenic Emissions of Mercury (Mg/yr)

44 Global Anthropogenic Emissions of Mercury (%) B3 Emissions Rest of the World 43% South Africa 2% China 26% India 10% South America 2% North America 7% Russia 3% Australia 1% Europe 6%

45 Global Anthropogenic Emissions of Mercury (%) B3 Emissions Waste disposal 8% Commercial gold production 17% Coal bed fires 2% VCM production 1% Other 3% Stationary combustion 35% Mercury production 2% Caustic soda production 7% Cement production 10% Non-ferrous metal production 13% Pig iron and steel production 2%

46 Total (Natural) B3 Emissions A B C D E F G A Bergan et al., 1999; B Mason and Sheu, 2002; C Lamborg et al., 2002; D Seigneur et al., 2004; E Selin et al., 2007; F Mason, 2009; G Pirrone et al., 2010 Evasion after mercury depletion events 4% Lakes 2% Forest 7% Biomass burning 13% Volcanoes and geothermal areas 2% Tundra/Grasslan d/savannah/prai rie/chaparral Desert/Metallife 9% rrous/nonvegetated Zones 10% Agricultural areas 2% Total Oceans 51%

47 B3 Emissions Mercury Emissions in 2020 and 2050 by Scenario and World Region (Mg yr-1) Year Scenario North America Central and South America Africa Europe, Russia, Middle East Asia and Oceania World Reference 2020 SQ [AMAP/UNEP, 2008] 2020 EXEC [AMAP/UNEP, 2008] 2020 MFTR [AMAP/UNEP, 2008] 2050 A1B [Streets et al., 2009b] 2050 A [Streets et al., 2009b] 2050 B [Streets et al., 2009b] 2050 B [Streets et al., 2009b]

48 B4. Global and regional modelling of Hg Global Hg concentration and deposition levels B4 Modeling Hg 0 concentration, ng/m λ = 85ºW North America Ensemble mean estimates of Hg concentration in air Latitude Hg 0 concentration, ng/m λ = 10єE Europe Latitude Hg 0 concentration, ng/m λ = 150ºW Pacific Ocean Latitude Hg 0 concentration, ng/m λ = 110ºE East Asia Latitude CTM-Hg GEOS-Chem GRAHM GLEMOS CMAQ-Hg ECHMERIT

49 B4. Global and regional modelling of Hg Global Hg concentration and deposition levels B4 Modeling Hg 0 concentration, ng/m Arctic Europe & N.Africa North America Hg 0 concentration East Asia South Asia Africa South America Australia & Oceania North Atlantic Pacific Total deposition flux, g/km 2 /y Arctic Europe & N.Africa North America East Asia South Asia Hg deposition Africa South America Australia & Oceania North Atlantic Pacific CTM-Hg GEOS-Chem GRAHM GLEMOS CMAQ-Hg ECHMERIT The differences between models are largest in the regions of sparse measurements (e.g. oceans, the Arctic, South Asia, and Africa) The largest uncertainty of simulated atmospheric deposition of Hg is associated with dry deposition

50 B4. Global and regional modelling of Hg Source attribution for Hg deposition B4 Modeling Deposition flux, g/km 2 /y Europe Deposition flux, g/km 2 /y North America Deposition flux, g/km 2 /y East Asia 0 GEOS-Chem GRAHM GLEMOS CMAQ-Hg 0 GEOS-Chem GRAHM GLEMOS CMAQ-Hg 0 GEOS-Chem GRAHM GLEMOS CMAQ-Hg Europe North America East Asia South Asia Other Natural & re-emission Multi-model source attribution study provides consistent estimates of source relative contributions despite the significant differences in emissions and chemistry between the models.

51 B4. Global and regional modelling of Hg Contribution of intercontinental transport to Hg deposition B4 Modeling Contribution of foreign sources, % Arctic Europe North America East Asia South Asia GEOS-Chem GRAHM GLEMOS CMAQ-Hg Intercontinental transport of Hg is significant, particularly in regions with few local emission sources. The contribution of foreign anthropogenic sources varies from 10% to 30%, on average in different regions

52 B4. Global and regional modelling of Hg Future changes of Hg deposition B4 Modeling Total emission, t/y Hg emission scenarios Europe North America 2005 East Asia South Asia 2020 SQ 2020 EXEC 2020 MFTR Other Relative deposition change, % Relative deposition change, % SQ 2020 EXEC Europe 2020 MFTR East Asia Relative deposition change, % Relative deposition change, % SQ 2020 EXEC North America 2020 MFTR South Asia SQ 2020 EXEC 2020 MFTR SQ 2020 EXEC 2020 MFTR Depending on applied emission scenario the change of Hg deposition between 2005 and 2020 will increase by 2-25% for SQ and decrease by 25-35% for EXEC and MFTR in different industrial regions.

53 5 B4. Global and regional modelling of Hg Hg 0 air concentration Evaluation of model uncertainty 50 Hg wet deposition flux B4 Modeling Model, ng/m 3 2 Model, g/km 2 /y Observed, ng/m 3 Observed, g/km 2 /y CTM-Hg GEOS-Chem GRAHM GLEMOS CMAQ-Hg ECHMERIT The model uncertainties range from 20% for the simulated air concentration of Hg 0, up to 80% for the simulated total deposition. The largest uncertainty of total deposition is associated with dry uptake.

54 B4. Global and regional modelling of Hg Key findings (1) B4 Modeling Intercontinental transport of mercury can occur through two pathways. One is the direct transport of emitted mercury plumes from one continent to another. The other pathway is through the mercury emission input of a source region into the global mercury pool. Contribution of foreign anthropogenic sources to annual deposition fluxes varies from 10% to 30%, on average anywhere on the globe. Besides, from 35 to 70% of total deposition to most regions consists of deposition contributed by global natural and secondary emissions East Asia is the most dominant source region contributing to 10-14% Hg to deposition in other regions, followed by contributions from Europe (2-5%), South Asia (2-3%) and North America (1-2%)

55 B4. Global and regional modelling of Hg Key findings (2) B4 Modeling The large contribution of natural sources and secondary emission of legacy Hg reduces response of Hg deposition to the reduction in anthropogenic emissions. However, the response could be larger in the long-term perspective due to the lagged effect of Hg recycling from planetary surfaces. Depending on the applied emission scenario the change of Hg deposition between 2005 and 2020 will increase by 2-25% for SQ and decrease by 25-35% for EXEC and MFTR in different industrial regions. In remote regions, such as the Arctic, the changes are expected to be smaller from 1.5-5% increase (SQ) to 15-20% decrease (EXEC, MFTR). The magnitudes of model uncertainties range from 20% for the simulated air concentration of Hg 0, up to 80% for the simulated total deposition. However, the simulation results for the relative source attribution have a smaller uncertainty at about 30%.

56 B4. Global and regional modelling of Hg Recommendations (1) B4 Modeling There is a need for a comprehensive interoperable measurement network for mercury in the environment to constrain models and track future mercury trends. Regular observations of wet and, in particular, dry deposition of Hg are highly required for the improvement of model formulation and Hg deposition estimates Better understanding of Hg chemistry through laboratory studies and field measurements are needed, particularly, for the gaseous and heterogeneous phase oxidation mechanisms, kinetics and products under different atmospheric conditions Reliable assessment of intercontinental or global-scale dispersion of Hg requires development of multi-media biogeochemical models that take into account the entire cycle of Hg in the environment. It is particularly relevant for evaluation of long-term trends, future scenarios and the impact of climate change on mercury pollution

57 B4. Global and regional modelling of Hg Recommendations (2) B4 Modeling Model estimates of the effect of Hg intercontinental transport on regional pollution levels highly depend on the availability of reliable anthropogenic emissions data and, in particular, on speciation of Hg emissions. Therefore, further improvements of global Hg emission inventories are needed In light of the importance of natural and secondary emissions for Hg concentration and deposition over the globe under current and future conditions, more studies are required for quantitative and mechanistic understanding of Hg emissions from various surfaces (soils, water, and vegetation) More efforts are needed for elaboration of future Hg emission scenarios as well as the application of chemical transport models in evaluating future changes of Hg pollution levels

58 Contribution of Intercontinental Transport to Atmospheric Mercury Deposition B5 Impact FINDING: Fish are the main source of human exposure to mercury. In regions that have not been contaminated by large local sources of mercury, the majority of population-wide human exposure is from marine fish consumption. Concentrations of mercury in commonly consumed migratory marine fish such as tuna and swordfish are affected by intercontinental transport and deposition of mercury to marine ecosystems. RECOMMENDATION: Reducing in global anthropogenic mercury sources is recommended as a method for reducing the mercury burden in pelagic marine fish and associated human exposures.

59 Tilefish Shark Swordfish Orange Roughy Marlin Tuna-fresh Tuna-canned alb Bluefish Grouper, Rockfish Scorpionfish Halibut Sea trout Figure 5.1. Reported mercury concentrations (ug/g wet weight) in fish sold in the U.S. commercial market. [Data from: U.S. FDA, 2006]. Sablefish Snapper Lobster Mackerel Skate Tuna-canned lght Impact on Human Health Cod Croaker Squid Whitefish Pollock Crab B5 Impact FINDING: Fish consumption patterns differ across geographic regions and vary according to traditional diets, recreational activities, and proximity to supply of fresh seafood products [Mahaffey et al., 2009; Moya, 2004]. Individual variability in mercury exposures across populations reflects these differences as well as the types and origins of seafood products consumed. RECOMMENDATION: Effectively managing MeHg risks requires information on the exposure pathway at both local and global scales. Most fish consumed globally are marine and estuarine species harvested from open ocean environments. Thus, understanding the impacts of intercontinental mercury sources on the distribution of mercury in open-ocean environments is especially important. Figure 5.2. Seafood consumption and total mercury intake from estuarine and marine fish and shellfish in the U.S. commercial market. Left panel: Seafood consumption estimated from NMFS fisheries supply data compared with available data for marine and estuarine fish consumption from the continuing study of food intake by individuals (CSFII) dietary survey data [U.S. EPA, 2002]. Right panel: Percentage of total mercury intake (product of seafood supply and mercury concentrations) for the top 15 seafood categories; intake is allocated by the source region for each of the fisheries products [Atlantic, Pacific, imported (foreign sources), and high seas landings]. Salmon includes both canned and fresh and frozen products; Anchovies et al. includes anchovies, herring, shad, and sardines; Flounders includes flounder, plaice, and sole; Haddock et al. includes haddock, hake, whiting, and monkfish; and Grouper et al. includes grouper and seabass

60 Impact on Terrestrial Ecosystems B5 Impact Figure 5.4. Soil storage and emissions of mercury in soils simulated by the model for pre-industrial and present-day conditions. Anthropogenic enrichment is computed as the difference between present-day and preindustrial budgets. Source: Smith-Downey et al. [2010].

61 Impact on Terrestrial and Frewater Ecosystems B5 Impact FINDING: Adverse impacts from recent and current anthropogenic mercury inputs into the environment is documented across broad areas of North America on fish, birds, and mammals. Because the ability to predict MeHg impacts in upper trophic level wildlife using models and measurements of air, sediment and water is presently limited, additional biological field sampling efforts are needed to reach a level of certainty for science-based decisionmaking. RECOMMENDATION: Based on recent advances in developing statisticallyreplicable and defensible field experiments for identifying LOAELs the use of wildlife for monitoring spatial gradients and temporal trends of environmental mercury loads related to atmospheric deposition is possible. Preliminary results suggest that intercontinental mercury transport contributes to adverse effects of mercury exposure on ecological health.

62 Impact on Polar Ecosystems B5 Impact FINDING: Observations made in the polar regions constitute direct evidence of a link between sunlight-assisted Hg(0) oxidation, greatly enhanced atmospheric Hg(II) wet and/or dry deposition, and elevated Hg concentrations in the polar snow-pack. Antarctic and Arctic coastal sites experience episodic mercury depletion events, which occur predominantly in the late winter and early spring. Polar regions receive most of their mercury from intercontinental transport and are highly susceptible to the effects of climate driven changes in atmospheric and oceanographic circulation. RECOMMENDATION: Further investigation is needed on the unique reactivity of mercury place in the troposphere of polar regions and the contribution of oxidized mercury from these regions to the global budget of atmospheric Hg. In addition, the role of snow and ice surfaces on deposition in these regions requires elucidation, including both experimental monitoring and modeling studies.

63 Impact on Marine Ecosystems B5 Impact Figure 5.5. Atmospheric Hg(II) deposition from Asian sources over the North Pacific Ocean. Source: Strode et al. [2008].

64 Impact on Marine Ecosystems B5 Impact Intercontinental transport from major hydrographic circulation patterns in the oceans Figure 5.6. Surface water total mercury concentrations in the North Pacific Ocean. Source: Sunderland et al. [2009].

65 Impact on Marine Ecosystems B5 Impact Intercontinental transport from major hydrographic circulation patterns in the oceans Figure 5.7. Enrichment of total mercury concentrations in intermediate waters of the North Pacific Ocean. Sources: [Laurier et al., 2004; Sunderland et al., 2009]. The enhanced local contribution to deposition off the Asian continent (Figure 5.5) that is also observed as enriched surface seawater concentrations (Figure 5.6) is the probable source of enriched immediate water mass concentrations in the eastern North Pacific (Figure 5.7).

66 Impact on Marine Ecosystems B5 Impact FINDING: Global changes in open ocean mercury concentrations can be attributed to intercontinental mercury transport as part of the global pool and localized deposition of mercury plumes from large source regions such as Northeastern Asia. In addition to atmospheric transport, large-scale oceanic transport can also be responsible for long-range transport of mercury from the original emissions source and likely impact marine fish concentrations globally. RECOMMENDATION: Additional research is needed on the importance of large scale oceanographic currents for redistributing mercury deposited in nearshore regions from concentrated source regions and coastal pollution sources.

67 Implications for Policy B5 Impact Present 2050 A1B 2050 A B B2 Figure 5.9. Modeled future mercury deposition scenarios for Asia based on the emissions scenarios developed by Streets et al. [2009]. Source: Corbitt et al. [2010].

68 Implications for Policy B5 Impact Figure Temporal evolution of fish MeHg source attributions for various model lake ecosystems to deposition scenarios for the Northeast and Southeast United States. Source: [Selin et al., 2010].

69 Thanks..