Mercury: Environmental Impact and Human Health
Mercury, a potent environmental pollutant, poses significant risks to human health. This overview explores the origins of mercury poisoning throughout history, including notable incidents such as the Minamata disaster and modern-day cases like Jeremy Piven's and Richard Gelfond's struggles with mercury poisoning from excessive fish consumption. The global issue of mercury contamination from fish consumption is highlighted, along with the biogeochemical cycle of mercury and its critical role in the atmosphere. The unique properties of elemental mercury and its transformation into toxic mercuric compounds are discussed.
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A brief human history of mercury poisoning Qinshihuang.jpgQin Shi Huang, 1st emperor of China Mad hatters http://upload.wikimedia.org/wikipedia/en/8/8d/Tomokos_hand.gif Minimata disaster Iraq grain disaster http://enhs.umn.edu/current/5103_spring2003/mercury/iraqmercury.gif 200 BC Karen Wetterhahn, Dartmouth professor 19th-20th century http://i.ytimg.com/vi/h049Hgfk-BI/hqdefault.jpg 1950s 1971 1997
The perils of eating too much fish Jeremy Piven, actor Richard Gelfond IMAX CEO http://img2-2.timeinc.net/people/i/2007/specials/redcarpet/sagnominees/jeremy_piven180.jpg Both hospitalized for extended time due to mercury poisoning from daily fish consumption over many years
Mercury from fish consumption: a global environmental issue EPA reference dose (RfD): 0.1 g kg-1 d-1 (about 2 fish meals per week) Children IQ deficits (fetal exposure) Well-established $8 billion per year cost in US Adult cardiovascular, fertility effects Suspected 1.6 Mercury biomagnification factor 1.4 Hg (mg/kg) 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Tilefish Tilefish Tuna-fresh Skate Skate Cod Cod Crab Crab Shark Shark Halibut Sea trout Sea trout Swordfish Marlin Marlin Bluefish Grouper, Rockfish Snapper Snapper Lobster Lobster Croaker Croaker Squid Squid Whitefish Salmon Canned Tuna (lt) Pollock Pollock Mackerel Sablefish Grouper, Rockfish Scorpionfish Orange Roughy Lobster Mackerel Sablefish Halibut Scorpionfish Whitefish Swordfish Tuna-canned alb Tuna-canned lght Bluefish Canned Tuna (alb) Orange Roughy
Mercury (Hg) is present in atmosphere as an elemental gas an amazing property shared only with noble gases Mass number = 80: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 Filling of subshells makes elemental Hg(0) stable, liquid, volatile Mercury can also shed its two outer electrons (6s2) to produce Hg(II) (mercuric) compounds oxidation Hg(0) reduction elemental mercury 6s2 Hg(II) mercuric compounds
Biogeochemical cycle of mercury: critical role of atmosphere ANTHROPOGENIC PERTURBATION: fuel combustion mining WATER-SOLUBLE VOLATILE oxidation ~10x natural Hg(II) Hg(0) [head] volcanoes erosion ATMOSPHERE OCEAN/SOIL Hg(0) Hg(II) particulate Hg reduction biological uptake burial uplift SEDIMENTS
Atmosphere enables global transport of mercury Present-day emission of mercury to atmosphere from coal and mining Implies gPresent-day cale transport of anthropogenic emissions Observed variability of atmospheric Hg implies an atmospheric lifetime against deposition of 0.5 years UNEP [2013]; Shah et al. [2021]
Mercury wet deposition is controlled by global transport EPA deposition data (circles), model (background) Florida T-storm https://www.eol.ucar.edu/dir_off/ASR/FY2000/images/hector1.jpg Global Hg(II) pool scavenging Highest mercury deposition in US is along the Gulf Coast, where thunderstorms scavenge globally transported mercury from high altitudes Selin and Jacob [2008]
How to oxidize Hg(0) to Hg(II) in the atmosphere? Radical oxidant X OH, Br Shah et al. [2021]
Sources of bromine atoms hv hv OH HOBr Br2 hv BrO CHBr3 bromoform Br weeks CH4 O3 HO2 HBr Br-- deposition ocean plankton plankton sea-salt aerosol
as simulated by GEOS-Chem model Shah et al. [2021]
UNEP Minimata Convention on Mercury (2013) Requires best available technology for coal-fired power plants Mercury mining to be banned in 15 years Regulation of mercury use in artisanal gold mining
Global biogeochemical model for mercury thermocline
Grasshopper effect keeps mercury in environment for decades mercury [head] Land Ocean rivers deep ocean SEDIMENTS Fate of an atmospheric pulse emitted at time zero: Atmosphere Surface soils Reservoir fraction Deep soils Coastal sediments Deep sediments 0 Amos et al. [2014]
What can we hope from the Minimata Convention? Effect of zeroing all human emissions by 2015 Zeroing human emissions right now would decrease ocean mercury by 50% by 2100, while keeping emissions constant would increase it by 40% Amos et al. [2013, 2014]
The wild card of climate change: potential mobilization of the large soil mercury pool Atmosphere: 5,000 tons Increasing soil respiration due to warmer temperature http://www.arcturius.org/chroniques/wp-content/uploads/2013/04/Ocean2.jpg http://www.wetlands.org/Portals/0/Gallery/Album/105/Copy%20(2)%20of%20(MS)%20peatland%20erosioin%20caused%20by%20overgrazing.JPG Global soils: 270,000 tons mercury Oceans: 330,000 tons Climate change may be as important as emission controls for the future of environmental mercury in the century ahead.
