Transcript Water Quality - Cloudfront.net

Water Quality
APES Ch. 14
Heavy Metals
 Lead:
 Rarely found naturally in drinking water
 Contaminates through lead containing pipes, solder, &
brass fittings
 Fetuses and infants are most sensitive
 Effects: brain-damage, damage nervous system &
kidneys
Heavy Metals
 Arsenic:
 Occurs naturally in rocks; can be dissolved in
groundwater
 Human activity like mining & industrial uses
 Can be removed by filtration or reverse osmosis
 Associated with cancers
 EPA standard in drinking water is 10 μg/L
 140 million in India drink arsenic contaminated
drinking water
Heavy Metals
 Mercury:
 Occurs naturally but increasing in drinking water due to
human activity
 Human activity:
 Coal burning
 Incineration of garbage
 Hazardous waste
 Medical & dental supplies
 Manufacture of cement (release from limestone in heating
process)
 Petroleum exploration (contaminated wastewater)
Heavy Metals
 Mercury Cont.:
 Inorganic Hg is not harmful but when released into
environment changed in methylmercury by bacteria
 Effects:
 Damage central nerve system (touch, taste, sight)
 Fetus and infants particularly susceptible
 Human exposure to methylmercury occurs mostly from
fish & shellfish
 Bioaccumulation up the food chain
 EPA: reduction of mercury emissions in cement
manufacturing & coal-burning power plants
Acid Deposition
 Acid Deposition: Release of sulfur dioxide & nitrogen
dioxide in atmosphere by industry is converted into
sulfuric acid/nitric acid and deposited 100’s km away
in form of rain or snow (a.k.a acid rain).
 Reduced pH in water bodies
 Lethal to aquatic organisms
 Coal scrubbers remove acidic gases
 Underground acidic water comes from mining
(reaction with pyrite)
 Reaction with acidic water can cause other harmful
metals to become soluble
Synthetics: Pesticides
 Concerns:
 Kill indiscriminately; lethal to unrelated species
 Ex: Endosulfan pesticide kills amphibians
 Side effects of pesticides can effect other species in
unintended ways.
 Ex: DDT & Bald Eagle
 Inert ingredients make pesticide more effective
 Ex: Roundup ingredient (used to penetrate waxy leaves)
is highly toxic to amphibians
Synthetics: Pharmaceuticals &
Hormones
 Common in streams:
 50% of tested streams contain antibiotics &
reproductive hormones
 80% contain non-prescription drugs
 90% contain steroids
 Low risk due to low concentrations but hormones can
effect tissues & are poorly understood
 Extent of hormone effects not understood
Synthetics: Industrial Compounds
 Chemicals used in manufacturing
 Used to be dumped directly into bodies of water
 Ex: Cuyahoga River – all animal life killed, caught on
fire several times; 1969 fire lead to movement to cleanup waterways.
 PCB (polychlorinate biphenyls)
 Manufacture of plastics & electrical transformers
 Lethal carcinogen that is still in the environment (US
stopped in 1979)
 Dredging sediments for PCB’s in 2009
Synthetics: Industrial Compounds
 PBDE’s (polybrominated diphenyl ethers)
 Mostly used in flame retardants in construction,
electronics, & clothing
 Causing concern: detected in fish, aquatic birds, &
human breast milk
 Can lead to brain damage in children
 EU, WA & CA have banned the manufacture
Oil Pollution
 Petroleum products are highly toxic to marine
organisms including algae (base of food chain)
 Persistent
 Extremely difficult to remove
 Sources:
 Undersea drilling platforms (5,000 in US)  Leak estimate – 146,000 kg (322,000 lbs) in NA; global –
0.3 to 1.4 million kg
 Ex: 2010 BP Oil Spill (206 million gal) contaminated
beaches, estuaries (habitat for fish & shellfish); one of
largest environmental disasters in US history
Oil Pollution
 Oil Tanker spills –
 Ex: Exxon Valdez in 1989 leaked 11 million gallons in
Gulf of Alaska
 Killed 250,000 seabirds, 2,800 sea otters, 300 harbor seals, &
22 orca
 20 years later  Clean-up is still continuing today
 Harmed populations rebounded including bald eagles &
salmon; not rebounded, killer whales & sea otters
 14,500 estimated gallons remain in ecosystems
 Now ships required to have double-hulled design
 Large fraction of oil in ocean occurs naturally
Oil Pollution Remediation
 Oil can either float or remain far below in plumes
 Remediation methods:
 Birds & mammals – cleaned by hand
 Floating oil –
 Contain it with a boom (plastic barriers) & then suck it
off the surface
 Apply chemicals that break-up the oil; can be toxic
 Genetically engineered bacteria that consumes oil
 Underwater plumes –
 Currently (BP spill) there is a plume that is 15 x 5 mi @
3,000 ft below
 No agreed upon method