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1 Presented by Scott Weir, Air Quality Coordinator Kickapoo Tribe in Kansas

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2 Chemistry of Mercury and Adverse Health Effects

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3 The Chemistry and Adverse Health Effects of Mercury Liquid metal Vaporizes easily Persistent Elemental - cannot be destroyed Health Effects/Biological damage Mercury in Environment and Ecosystems Mercury cycle Aquatic systems and methylation Biological amplification up the food chain

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4 Unusual properties of mercury created intense interest among alchemists Symbol for Hg Ouroboros

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5 Amalgamation Peculiar affinity for certain other metals Attracted attention of alchemists Forms an amalgam with silver or gold was used in dental fillings reflective surface on antique mirrors used in gold mining, past and present Rapidly corrodes aluminum upon contact possible sabotage of aircraft in World War II

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6 Elemental Mercury Generally obtained from cinnabar (HgS), a red ore Only metal which occurs as liquid at standard temperature and pressure Slowly vaporizes at ambient temperatures Freezes at -38.83 o C (-37.89 o F) Once known as hydrargyrum (from Greek words meaning silver water) hence chemical symbol Hg Also called quicksilver (i.e., live silver)

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7 Hg occurs in three oxidation states Hg(0) Elemental mercury Metal or vapor Hg(I) monovalent mercury ion; Hg 2 2+ E.g., Mercurous Chloride: Hg 2 Cl 2 Hg(II) divalent mercury ion; Hg 2+ E.g., Mercuric chloride: HgCl 2

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8 Divalent Mercury: Hg 2+ Most common form in organic and inorganic mercury compounds Easily washed out of air with precipitation Referred to as reactive gaseous mercury

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9 Toxicity of Mercury Mercury poisoning Inhalation or ingestion of HgS dust Ingestion of water soluble mercuric chloride (HgCl 2 ) or methylmercury ([CH 3 Hg] + ) Inhalation of mercury vapor Ingestion of contaminated fish/seafood

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10 Toxicity of Mercury Severity of health effects depends on 1)chemical form of mercury 2)dose received 3)duration of exposure 4)age of person exposed 5)route of exposure (inhalation, ingestion, etc.) 6)overall health of person exposed

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11 Toxicity of Elemental Mercury Mercury is a potent toxin Vapor is harmful chronic exposure leads to Mad Hatter Disease (erethism mercurialis) Loss of hair, teeth and nails Deafness Lack of coordination Poor memory Emotional disturbances Kidney damage

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12 Toxicity of Mercury In general, the younger the patient, the more severe the effects Fetuses, infants and children primary adverse health effect is impaired neurological development Prenatal exposure can be especially severe Negative impacts on cognition, memory, attention span, language development, and fine motor / spatial skills are well documented

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Sources and the Global Pool of Atmospheric Mercury

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Atmospheric Mercury Mercury occurs in three forms in atmosphere Elemental Vapor (Hg 0 ) Predominant form in atmosphere Some converted to reactive gaseous mercury (Hg 2+ ) Gaseous Divalent (Hg(II)) Predominant form flushed from atmosphere by precipitation Particulate Phase (Hg(p))

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Atmospheric Mercury Most circulating atmospheric mercury is Hg(0) vapor Readily transported and remains in atmosphere for 6 months to 2 years Hg(0) gradually oxidized to water-soluble divalent mercury (Hg 2+ ) Removed from atmosphere by wet deposition

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Atmospheric Mercury Inorganic compounds containing divalent mercury occur in atmospheric aerosols Mercuric chloride: HgCl 2 probably most prevalent compound Mercuric nitrate: Hg(NO 3 ) 2 Mercuric sulfate: HgSO 4

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Natural Sources of Atmospheric Mercury Hg occurs in deposits worldwide, mostly as cinnabar (mercuric sulfide, HgS) Natural emissions to atmosphere volcanic and geothermal activity (including oceanic vents) additional input from erosion of geologic surfaces containing mercury

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Natural vs. Anthropogenic Sources of Atmospheric Mercury Natural sources (e.g., volcanoes) = about one-third of atmospheric Hg emissions Anthropogenic sources (e.g., coal-fired EGUs & gold mining) = about one-third of atmospheric Hg emissions Remaining one-third of emissions due to recycling of Hg already in the environment

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Anthropogenic Sources of Atmospheric Mercury Human-generated portion of mercury emissions : 65% stationary combustion (mostly coal-fired power plants, which account for 40% of U.S. emissions) 11% . gold mining 7% . non-ferrous smelters 6.5% . cement production 3.0% . waste disposal 3.0% . caustic soda production 4.5% . other sources

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Part of the problem: Mercury is a natural contaminant in coal. About 40% of the mercury in fish originates with coal-fired power plants.

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An example

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There are 18 coal-fired Power Plants within 150 miles of the Kickapoo Tribe in Kansas

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Coal Train 1.5 miles long 150 cars Car capacity: 102-121 tons Train capacity: 15,300 - 18,150 tons

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In 2011, the 6 major power plants to the south of the KTIK reservation burned 18,347,194 tons of coal.

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Thats 36,694,388,000 pounds of coal

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In 2011, the 6 major power plants to the south of the KTIK reservation emitted 1,512.4 lbs. of Hg.

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There is some good news

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31 and more Accumulation rates in four rural eastern Minnesota lakes and four Minneapolis-area lakes peaked in the 1960s and 1970s, declined in 1980s Declining mercury accumulation rates in 1980s are attributed to reductions in regional mercury sources, resulting from: decreased industrial uses of mercury; improved technologies at coal-burning facilities; shift from coal to natural gas for heating; and decreased waste incineration

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and even more MERCURY AND AIR TOXICS STANDARDS (MATS) Replaces Clean Air Mercury Rule (CAMR), which was based on cap and trade Applicable to new electricity generation facilities Establishes emission limits for Hg as well as for other metals, particulate matter and acid gases

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Mercury in the Environment and Introduction to Deposition

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34 Mercury in the Environment Persistent pollutant Remains in the atmosphere for 6 months to 2 years Accumulates in soils, sediments, ponds and lakes Bioaccumulates efficiently, especially in aquatic systems

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35 Mercury Cycle

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36 The Mercury Cycle Inorganic mercury from coal-burning emitted as gaseous elemental mercury, reactive gaseous mercury and particle-bound mercury Gaseous elemental mercury directly enters the global atmospheric pool circulates for up to 2 years Reactive gaseous mercury and particle-bound mercury generally deposited locally and regionally

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37 The Mercury Cycle (cont.) Inorganic mercury (from coal-fired EGUs or mercury/gold mining operations) enters aquatic systems via deposition and runoff Some inorganic mercury attaches to suspended sediment, but... Some enters organic-rich wetlands converted to methylmercury by natural bacterial processes enters streams and lakes with organic matter Some inorganic and methylmercury remains in the soil Some leaves via stream flow, and Some re-emitted from soil to atmosphere

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Methylmercury [CH 3 Hg] +

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39 Methylation of Mercury Occurs primarily in wetlands (but also in sediments) Abundant organic matter Low dissolved oxygen levels Sulfate-reducing bacteria Breakdown organic matter Use sulfate for respiration Methylmercury is by-product of process

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40 Methylation of Mercury Moderate sulfate levels generally enhance formation of methylmercury Low sulfate levels limit methylation High sulfate levels inhibit methylation because sulfate is converted to sulfide, which binds directly to mercury Newly flooded lands and repeated wetting/drying cycles result in high methylation rates due to rapid decay of organic matter and sulfate reduction

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41 Ecosystem Sensitivity for Mercury Methylation Deposition: only one factor affecting amount of mercury in fish Water bodies vary greatly in extent to which deposited mercury is methylated Factors that affect methylation Dissolved organic carbon pH Sulfate concentration Acid neutralizing capacity Wetlands or other hydric soils

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42 Methylmercury [CH 3 Hg] + Bioaccumulative environmental toxin Formed from inorganic mercury by action of anaerobic microorganisms in aquatic systems Sulphate-reducing bacteria are primarily responsible Methylation predominantly occurs in wetland/floodplain soils and lake sediments In lakes, methylmercury is also de-methylated in sediments and removed in outlet streams

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43 Methylmercury [CH 3 Hg] + Not readily eliminated from organisms Biological half-life in aquatic ecosystems is 72 days Biomagnified in aquatic food chains from bacteria and plankton, through macroinvertebrates, to herbivorous fish and to piscivorous (fish-eating) fish Predators, i.e., fish-eating birds and mammals (including humans), are at top of food chain and receive highest doses Concentration of methylmercury in top aquatic predators can reach a level a million times higher than level in water

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44 Bioaccumulation

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45 Methylmercury Exposure Methylmercury levels in freshwater fish vary with the level of deposition of mercury from atmosphere Also dependent upon methylation rate / bacterial activity Models suggest 70% of mercury deposited into ocean is re-emitted to atmosphere But methylmercury stays in upper ocean for about 11 years

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46 Methylmercury Exposure (cont.) Research indicates that mercury content in many marine animals is 12 times higher than pre-industrial levels - This implies that much of mercury in marine animals comes from anthropogenic sources Indigenous populations in Arctic who consume top marine predators (fish, seals, and whales) have some of worlds highest exposures to methylmercury

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47 Biochemistry of Methylmercury [CH 3 Hg] + Readily combines with anions such as chloride (Cl ), hydroxide (OH - ) and nitrate (NO 3 ) Very high affinity for sulfur-containing anions, particularly thiol (-SH) groups on amino acid cysteine Methylmercuric-cysteinyl complex is recognized in body as essential amino acid methionine

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48 Structural similarity between l-methionine and methylmercury-cysteine

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49 Human Health Effects of Methylmercury [CH 3 Hg] + Completely absorbed by human gastrointestinal tract in utero damage readily transported across placenta absorbed by developing fetus Incorporation in proteins results in abnormal molecular structure affects cellular structure and function Biological persistence half-life in human bloodstream is about 50 days Causes severe neurological damage in infants and children Linked to increased risk of cardiovascular disease in adults

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50 Fish Tissue Sampling Provides Information About Mercury Levels in Local Fish Populations

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51 KTIK has two ponds under a fish consumption advisory to limit mercury exposure

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For Additional Information United Nations Environment Programme (UNEP) publications about mercury http://www.unep.org/hazardoussubstances/Mercury/Informationmaterials/ReportsandPublication s/tabid/3593/Default.aspx http://www.unep.org/hazardoussubstances/Mercury/Informationmaterials/ReportsandPublication s/tabid/3593/Default.aspx UNEP - Global Mercury Assessment 2013: Sources, emissions, releases and environmental transport http://www.unep.org/publications/contents/pub_details_search.asp?ID=6282 http://www.unep.org/publications/contents/pub_details_search.asp?ID=6282 UNEP - Technical Background Report for the Global Mercury Assessment 2013 http://www.amap.no/documents/doc/Technical-Background-Report-for-the-Global- Mercury-Assessment-2013/848 http://www.amap.no/documents/doc/Technical-Background-Report-for-the-Global- Mercury-Assessment-2013/848 UNEP - Mercury: Time to act http://www.unep.org/publications/contents/pub_details_search.asp?ID=6281 http://www.unep.org/publications/contents/pub_details_search.asp?ID=6281 USGS publication pending; under peer review The Quality of Our Nations Waters: Mercury in the Nations Streams Levels, Trends and Implications