Metals and Mercury

1. Metals and Mercury

2. Biological pollution Discovery of coliform bacteriahad the greatest impact on municipal water systems and water treatment. 1/3 weight of average uninfected human waste Not necessarily a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present Coliforms are naturally present in the environment; fecal coliforms only come from human and animal fecal waste.

3. Forms of Water Treatment Suspended Solids Flocculation Sand filtration Flocculation – bringing together of high numbers of small particles to create larger particles which settle out of water quickly. Advanced treatment uses chlorine disinfection To remove pathogenic organisms from water.

4. Scientists demonstrate that microorganisms can cause disease. 1880s First application of chlorine disinfectants to U.S. municipal water facilities in Jersey City and Chicago. 1908 First U.S. drinking water bacterial standard. 1915

5. Over 1,000 U.S. cities employ chlorine disinfection. 1918 More than 19,000 municipal water systems operate throughout the U.S. 1960

6. Biological Pollution and Chlorination Chlorine is currently employed by over 98 percent of all U.S. water utilities that disinfect drinking water

7. Effectiveness of Chlorination: Typhoid Yardstick 174 per 100,000 persons died of Typhoid in 1891 bacterium Salmonella typhi Deaths per 100,000 1860 1910 1935 Today: < 40 per 200 million people

8. Metals: Mercury

9. Heavy Metals and Metalloids Arsenic Erosion of natural deposits; pesticide waste, runoff from glass & electronics production wastes, treated lumber, groundwater Mercury Erosion of natural deposits; discharge from refineries and factories; runoff from landfills, coal burning Lead Corrosion of household plumbing systems; natural deposits, paint, fuels, electronics

11. Arsenic Wells in Floodplain and Delta Sediments Natural erosion of arsenic to water- bearing units. Well depths between 20m and 100 m Water Bearing Muds

12. WHO/U.S limit: 10 ppb Bangladesh limit: 50 ppb Some wells contain 500 - 1000 ppb Majority of wells > 50 ppb arsenic

13. Lead (Plumbum) Father of all metals Possible cause of the dementia which affected Roman Emperors and Citizens. -lead pipes -lead acetate sugar of lead sweetener for wine Contemporary Sources: Paint, ceramics, glass, soils, pipes, Solder, brass faucets, gasoline

14. Mercury Got Fish?

15. Mercury Advisories 70% of states Where does it come from?

16. Enters water bodies principally from the atmosphere Mercury is naturally occurring (coal, volcanism, rock weathering) The number 1 anthropogenic source is the combustion of coal 48 tons of elemental mercury to the atmosphere each year.

17. Mercury The drinking water standard for Mercury is 0.002 mg/L. 1 gram annually Electrical products such as dry-cell batteries, fluorescent light bulbs, switches, and other control equipment account for 50% of mercury used.

18. Fluorescent Lights A typical fluorescent lamp is composed of a phosphor-coated glass tube with electrodes located at either end. The tube contains a small amount of mercury vapor. When a voltage is applied, the electrodes energize the mercury vapor, causing it to emit ultraviolet (UV) energy. The phosphor coating absorbs the UV energy, causing the phosphor to fluoresce and emit visible light. Phosphor Coating Hg gas UV Voltage

19. Recycling and Handling Each year, an estimated 600 million fluorescent lamps are disposed of in US landfills amounting to 30,000 pounds of mercury waste.

20. Forms of Mercury The dominant inorganic forms are Hgo and Hg2+. Hg2+ often occurs as HgCl2 (mercuric chloride) in many aqueous environments. Hg2+ (inorganic) interacts with soil and sediment particles (- charge) becoming part of lake bottom sediments (limits availability)

21. - charge Interaction with Sediment Particles - charge Small organic and Inorganic particles Hg2+ Hg2+ Hg2+ - charge

22. Mercury Bound to Sediments Mercury, however, can undergo chemical changes in lakes which render mercury more environmentally dangerous Hg2+ Hg2+ sediments Negatively charged particles bind mercury And retain it in bottom sediments. - charge

23. Mercury Methylation Mercury can be converted to more toxic forms in bottom sediments under anaerobic conditions

24. Mercury Methylation Methylation: conversion of inorganic forms of mercury, Hg2+,to an organic form: methyl mercury under anaerobic conditions Hg2+(CH3Hg+) metylmercury Methylmercury is strongly accumulated in the body and is generally more toxic than inorganic Hg

25. Mercury Methylation • Requires 4 elements: • anaerobic conditions • a carbon source (organic sediments) • a source of sulfur (SO4-) • sulfur reducing bacteria Occurs primarily in bottom sediments as a byproduct of the life processes of anaerobic sulfate-reducing bacteria (SO4 to HS-) that live in high sulfur, low oxygen environments. Sulfate Respiration C6H12O6 + 3SO42- + 3H+ = 6HCO3- + 3HS- When sulfur accepts electrons it is said to be “reduced”.

26. The exact role of sulfate-reducing bacteria In mercury methylation is poorly understood However, bacterial sulfate respiration requires sulfate. The addition of sulfate to water stimulates the metabolic activity of sulfate-reducing bacteria and the inadvertent methylation of inorganic mercury Sulfate concentrations in EAA runoff and Lake Okeechobee average more than 50 times background concentrations than in the pristine Everglades Sulfate

27. Hg2+ from coal, volcanism, rock weathering, point sources Water Sediments (Bound) Sulfur reducing bacteria, low O2 methylmercury Aquatic Organisms

28. Enhanced Risk Methylmercury attaches to proteins in animals (enters food chain) Methylmercury has a half-life in human blood of about 70 days (almost twice as long as inorganic mercury (Hg2+). Methylmercury is strongly accumulated in the body and is generally more toxic than inorganic Hg Bioaccumulation: concentration of a chemical in organisms relative to the amount in water. Biomagnification: concentration of a chemical in organisms as it moves up the food chain.

29. Bio-magnification

30. Bioconcentration and Biomagnification Chemical Concentration in organism Chemical Concentration in water BAF =

31. Minamata Bay Chisso Corporation, a company located in Kumamoto Japan, dumped an estimated 27 tons of mercury compounds into Minamata Bay Between 1932 and 1968. 1963 plastics, drugs, and perfumes acetaldehyde As of March 2001, 2,265 victims had been officially recognized (1,784 died) and over 10,000 had received compensation from Chisso

32. Assessing Your Risk http://www.edf.org/page.cfm?tagID=17694 http://www.mercuryfacts.org/fSafeFish.cfm Nearly all fish and shellfish contain traces of methylmercury. However, larger fish that have lived longer have the highest levels of methylmercury because they've had more time to accumulate it. These large fish (swordfish, shark, king mackerel and tilefish) pose the greatest risk. Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish. Fish sticks and "fast-food" are commonly made from fish that are low in mercury.