water quality apes ch. 14. heavy metals lead: rarely found naturally in drinking water ...
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Water QualityWater QualityAPES Ch. 14APES 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 clean-up 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