MERCURY AS A GLOBAL POLLUTANT

1. MERCURY AS A GLOBAL POLLUTANT JOHAN C. VAREKAMP EARTH & ENVIRONMENTAL SCIENCES WESLEYAN UNIVERSITY MIDDLETOWN CT USA

2. Mercury droplets on cinnabar (HgS)

3. MERCURY AND HUMAN HEALTH Mercury has no known biological function and binds tightly to sulfhydryl groups, inhibiting molecular functions -SH • reduces membrane permeability • reacts with and disrupts phosphate bonds in ATP/ADP • replaces cations in important molecules

4. ENVIRONMENTAL CONCERN HUMAN HEALTH CONCERN: HG IS A NEUROTOXIN

5. Victim of the “Minamata Bay” (Japan) tragedy, the first documented disaster of Hg pollution (1956)

6. Exposure to mercury? • Eating fish or shellfish • Breathing vapors (home, work) • Dental work and medical treatments • Religious rituals that include Hg inhalation (Santaria in Haiti)

7. Fish Consumption Primary form of human exposure to methylmercury is through fish consumption. Population at greatest risk: small children and pregnant women that consume fish EPA - RfD is 0.1 ug MeHg/day

11. Never ending discussion about the magnitude of the pre-industrial Hg flux versus the human-made flux.

13. Delivery pathways of Hg to the coastal environment • Atmospheric deposition in the watersheds and fluvial transport to the coast • Point source contamination on land with fluvial transport to the coast • Direct discharge through outfall pipes of waste water treatment plants • Dredge and sludge dumping

14. Some important forms of Mercury in the environment: CH3-Hg+ organic, charged, lipophilic Hg2+ oxidized Hg0 reduced, elemental,volatile CH3-Hg-CH3 organic, volatile, lipophilic

15. aerobic volatilization Hg0 bioaccumulation reduction CH3-Hg+ Hg2+ demethylation (CH3)2-Hg methylation (Sulfate reducing bacteria) anaerobic

16. Hg Transport • Dissolved metals (e.g., in complexes with dissolved organic matter) • Attached to fine particles: • Inorganic • Organic

17. Repositories of metals • Coastal subtidal sediments (delivery mainly by particulate deposition) • Coastal salt marshes and estuarine marshes (delivery mainly by particulate deposition and to some degree through in situ atmospheric deposition)

19. Sediment Cores • Environmental archives that contain contamination records of metals • Record can be blurred by • Chemical mobility in the sediment column • Discontinuous sediment deposition (flood deposits) • Bioturbation

23. Mercury Levels • Normal modern soil background levels for mercury in the northeast USA are around 200 to 300 parts per billion • Mostly due to atmospheric deposition • Sediment samples with higher Hg suggest point sources of Hg in watershed • Hg inventories: total amount of Hg deposited on 1 cm2 over the full pollution period

24. GRAIN SIZE EFFECT ON HG INVENTORIES

25. SR FI PI DB

26. Mercury profile core Chapman Pond, CT River, CT

27. Mercury profile from core BFB3A, Farm River marsh, Branford, CT

35. THE STILL RIVER, WESTERN CONNECTICUT

38. ~1955

39. Fowler Island core, Housatonic River

40. Pope Island core, Housatonic River

42. Floods of 1955 Wooster Square, Danbury

43. The floods of 1955 in Waterbury, CT after two hurricanes hit in a few weeks time

44. Norwalk River Core 1955 1900 1820

45. Housatonic River, Still River, Norwalk River: strong evidence for Hg from hat-making sourcesSource signals modified by floods The return of the mad hatter

46. Lee Hat Factory Mallory Hat Factory

47. 1985 End of an Era! The last hat operations, a merger of Mallory, Lee, Stetson, and Disney, ceased in 1985.

48. EVERYONE wore hats. Men, women,

50. The Carroting Solution …had nothing to do with vegetables. This bright yellow-orange solution of mercury and nitric acid was used to treat animal fur from pelts. It made the fur fibers mat into felt more easily.