Mercury Biogeochemical Cycle

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1 Mercury Biogeochemical Cycle Hao Zhou 10/09/2017 Today s Discussion Background Compartments Anthropogenic inputs Atmosphere Arctic Soil Freshwater/wetlands Ocean 1

2 Liquid at room temperature Not biodegradable Can exist at significant concentration in the vapor phase Humans cannot create or destroy mercury Bio accumulates in aquatic ecosystem (Contaminated fish ) Measured at very low levels on short time scales Neurological development for infants and children (Methylmercury ) Neurologic and cardiovascular effects on adults (Methylmercury ) 2

3 Mercury (Hg) 66 th most abundant element in Earth s crust Found largely in the ore cinnabar China s first emperor 3

4 From: Trace Elements In Terrestrial Environments (2001) Species of Hg Elemental: Hg 0 Oxidized Hg (2+ or 1+): gases/particles Inorganic Hg: HgCl 2 HgO, Hg(NO 3 ) 2 Organic Hg: CH 3 Hg, (CH 3 ) 2 Hg Environment Atmosphere Water Soil Species Elemental, oxidized Hg Oxidized Hg Elemental, Oxidized Hg 4

5 Mercury Why do we care? Mercury cycle converts inorganic forms (mercury metal) to organic forms (methylemercury) Inorganic mercury in high doses is toxic Methylmercury is a neurotoxic pollutant in very low doses Acute mercury poisoning is called Minamata Disease Methylmercury bio accumulates and bio concentrates upward through the food chain Minimata Disease Minamata disease A neurological syndrome caused by severe mercury poisoning First discovered in Minamata city, Japan, in 1956 Caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation's chemical factory 2,265 victims had been officially recognized as having Minamata disease (1,784 of whom have died) 1.Photo by Eugene Smith

6 How Mercury influence people Adverse Health Effects of Hg Nervous system, renal, cardiovascular effects, cancer, genotoxity, reproductive and developmental effects, gastrointestinal (digestive system) and hepatic (liver) effects, effects on the skin, effects on the immune system, effects on the thyroid gland. 6

7 Global Hg Cycle Selin et al., 2009, copyright 2007 National Academy of Sciences, U.S.A. Global Hg Cycle 2013 UNEP 7

8 Hg Bioaccumulation methylmercury in lake water:1 microorganisms 10 5 macroorganisms 10 6 fish, birds, and humans mercury/default.asp?lang=en&n=d721ac1f 1 Hg in Different Compartments Preindustrial Modern Lindberg et al., 2007 copyright, American Geophysical Union 8

9 Anthropogenic Influences on the Hg Biogeochemical Cycle Hg as a commodity 9

10 Quicksilver Historic Activities Mercury has been mined for over 3500 years Cinnabar yields vermillion (red dye) used in crafts for thousands of years Largely mined in South America by both the Roman Empire and Spanish colonists Life expectancy was under two years for miners Hg content in Wyoming ice core UNEP,

11 Anthropogenic Sources 2013 UNEP Global anthropogenic Hg emission map, UNEP UNEP

12 Temporal variation of Hg anthropogenic emissions UNEP 2013 Global control Minamata Convention on Mercury Products Hg contained production, export and import will be banned by Artisanal and Small Scale Gold Mining Countries need to draw up strategies to reduce the amount of mercury used by small scale miners Power Stations to Cement Factories The new treaty will control mercury emissions and releases from various large industrial facilities 12

13 Minamata Convention 128 signatures, 19 ratifications Mercury control in U.S. History of Regulating Mercury in the U.S. The Clean Air Act provides that EPA must take several steps before regulating air toxics emissions (such as mercury) from power plants. EPA proposed a rule with two basic approaches for controlling mercury from power plants. One approach would require power plants to meet emissions standards reflecting the application of the "maximum achievable control technology" (MACT) determined according to the procedure set forth in section 112(d) of the Clean Air Act. EPA finally issued the final Clean Air Mercury Rule in 2005 EPA proposed a rule that would reduce emissions from new and existing coal and oil fired power plants. This proposed rule would replace the court vacated Clean Air Mercury Rule. EPA has decided to deny all remaining requests of reconsidering certain aspects of the Mercury and Air Toxics Standards (MATS) for power plants. But, the supreme court rules against it this summer, requiring EPA to consider the landmark standards "Utility Air Toxics Study" report to Congress. EPA focused on power plants, analyzing emissions of toxic air pollutants, including mercury. The D.C. Circuit vacated EPA's rule removing power plants from the Clean Air Act list of sources of hazardous air pollutants. At the same time, the Court vacated the Clean Air Mercury Rule In April 2016, the U.S. Supreme Court changed its perspective and refused to stay the MATS. Therefore, MATS became the first standard in the United States for mercury emissions from power plants Source: Regulating Action, EPA. 13

14 Knowledge of atmospheric mercury (Hg) cycling processes and accurate mass balances on local, regional, and global scales is needed to assess Hg impacts on humans, animals, and ecosystems, and to establish Hg emission control policies. A synthesis of research needs for improving the understanding of atmospheric mercury cycling, Atmospheric Chemistry and Physics, 17, , 2017 Hg in the atmosphere Mercury has a significant atmospheric component Can be transported 1000s of km Transport leads to contamination far from point sources of pollution via wet and dry deposition Atmospheric chemistry plays an important role in dry deposition Once transported the landscape takes over converting inorganic to organic 14

15 Atmospheric Mercury Elemental gaseous mercury, Hg(0) Weakly water soluble Global background concentrations ~1 to 2 ng/m 3 Atmospheric lifetime ~0.5 to 2 years Typically >95% of atmospheric Hg Reactive gaseous mercury, RGM(GOM) Divalent, oxidized Highly reactive & water soluble, readily wet/dry deposited Short lifetime (hours to days), pg/m 3 concentrations Particle bound mercury, PBM Condensed Hg, semi volatile Hg bound to aerosols Readily wet/dry deposited Short lifetime (hours to days), pg/m 3 concentrations days to weeks, local source Source: Dirk Felton, NYS Department of Environmental Conservation Atmospheric Mercury Fate Processes Atmospheric Mercury Fate Processes (1) Cohen, Mark, et al. "Modeling the atmospheric transport and deposition of mercury to the Great Lakes." Environmental Research 95.3 (2004):

16 Hg in the Atmosphere Corbitt et al Environmental Science and Technology Mercury in the Arctic 16

17 Mercury in the Arctic Arctic ecosystems are fragile Methyl mercury form is a neurotoxin and accumulates in living organisms Piscivorous fish Polar Bears Whales Seals Indigenous Arctic peoples diet heavily reliant on these organisms Valera et al NeuroToxicology; Tian et al Environment International Mercury in the Arctic Metal Ions in Biological Systems (2005) 17

18 Mercury and Ozone in the Arctic Surface Layer From Steffen et al ACP Mercury in Soils 18

19 Mercury in Soils Gaseous Mercury in Soils Obrist et al ES&T 19

20 Hg Emissions from Soils From: Agnan et al ES&T Hg Emissions from Soils From: Agnan et al ES&T 20

21 Hg in Freshwater Systems Hg in Freshwater Systems Metal Ions in Biological Systems (2005) 21

22 Hg in Freshwater Systems Hg species in water From: Trace Elements In Terrestrial Environments (2001) 22

23 Hg in fish Hg in the Oceans 23

24 3 benefits brain/ 24