Today everybody is downwind or downstream from somebody else.

-- William Ruckelshaus

• point sources (e.g., factories, sewage treatment plants, mines, oil wells, oil tankers);

• nonpoint sources (e.g., acid deposition, substances picked up in runoff, seepage into groundwater);

• nonpoint source water pollution from agriculture is largest source of water pollution in the U.S. (64% of pollutants into streams & 57% of pollutants entering lakes)

Sources of Pollution

• disease–causing agents (500+ identified)

• 3.2 mil die yearly from contaminated water complications

• oxygen demanding wastes

• Plant debris, animal wastes

• fertilizers

• water–soluble inorganic chemicals

• Acids, salts, metals

• organic chemicals

• Pesticides, oil & gasoline, plastics, PCBs

• sediment

• water–soluble radioactive isotopes

• thermal pollution

Types & Sources of Water Pollution

decomposing wastes deplete dissolved oxygen

•dissolved oxygen (DO) indicatorof water quality

Oxygen–Demanding Wastes

• amount of dissolved oxygen needed by aerobic decomposers to break down organic materials in a certain volume over a 5–day incubation period at 20° C

• greater BOD --> more rapidly oxygen depleted

• consequences of high BOD are the same as those for low dissolved oxygen

• Sources of BOD:• leaves and woody debris• dead plants and animals• animal manure• effluents from pulp and paper mills• wastewater treatment plants• feedlots• food-processing plants• failing septic systems• urban stormwater runoff

Biological Oxygen Demand (BOD)

Clean ZoneDecomposition

Zone

Septic ZoneRecovery

Zone

Clean Zone

Normal clean water organisms(trout, perch, bass,

mayfly, stonefly)

Trash fish(carp, gar,leeches)

Fish absent, fungi,sludge worms,bacteria

(anaerobic)

Trash fish(carp, gar,leeches)

Normal clean water organisms(trout, perch, bass,

mayfly, stonefly)

8 ppmDissolved oxygen (ppm)

Biological oxygendemand

8 ppmTypes of

organisms

BOD & DO & Water Quality

"oxygen sag curve"

Flowing water can often recover rapidly by dilution & decay.© Brooks/Cole Publishing Company / ITP

Pollution of Fresh Water

results when human activities accelerate input of nutrients (which?) to a lake

© Brooks/Cole Publishing Company / ITP

Cultural Eutrophication

Lakes and reservoirs pollution persists due to

•Little mixing between layers

•Little flow into & out of

•Turnover can take as long as 100 years

• basin contains >95% of fresh surface water in U.S. & 20% of world

• severe cultural eutrophication since the 1960s

• $20 billion pollution–control program improved water quality since 1972

• ¾ of shoreline still not suitable for swimming

Fig. 12–22© Brooks/Cole Publishing Company / ITP

Great Lakes

Organic chemicals pollution: Cuyahoga River, Cleveland OH

So polluted that it caught on fire in 1868, 1936, 1959, 1969 and burned for several days.

Today: not flammable, water quality is good enough for boating

concentrations increase at increasing levels in the food chain -- PCBs (polychlorinated biphenyls), heavy metals, certain pesticides

© Brooks/Cole Publishing Company / ITP

Biological Magnification

Groundwater

Supplies nearly ½ of drinking water in the US (95% of drinking water in rural areas)

Many pollutants can seep into groundwater (pesticides, fertilizers, gasoline, organic solvents)

Fig. 21-7, p. 501

Coal strip mine runoff

Polluted air

Deicing road salt

Pesticidesand fertilizers

Hazardous waste

injection well

Pumping well

Gasoline station

Water pumping well

LandfillSewer

Buried gasoline and solvent tanks

Cesspool, septic tank

Groundwater flow

Confined aquifer

Confined freshwater aquifer

Unconfined freshwater aquifer

Accidentalspills

Waste lagoonLeakage from faulty casing

Discharge

• coastal areas most impacted – especially wetlands & estuaries, coral reefs, & mangrove swamps;

• half of world's population lives within 100 km (60 miles) of oceans & 14 of 15 largest cities coastal;

• in U.S. about 35% of municipal sewage discharged virtually untreated in marine waters;

• ocean ultimate repository of waste;

• dumping of industrial waste directly into ocean off U.S. coasts stopped, but many countries still dump large quantities of toxic substances.

© Brooks/Cole Publishing Company / ITP

Ocean Pollution

Fig. 21-10, p. 505

Healthy zoneClear, oxygen-richwaters promote growthof plankton and sea grasses,and support fish.

Oxygen-depleted zoneSedimentation and algaeovergrowth reduce sunlight,kill beneficial sea grasses, useup oxygen, and degrade habitat.

Red tidesExcess nitrogen causesexplosive growth of toxicmicroscopic algae,poisoning fish andmarine mammals.

FarmsRunoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.

Toxic sedimentsChemicals and toxic metals contaminate shellfish beds, kill spawning fish, andaccumulate in the tissues of bottom feeders.

Construction sitesSediments are washed intowaterways, choking fish and plants, clouding waters, and blocking sunlight.

Urban sprawlBacteria and viruses fromsewers and septic tanks contaminate shellfish beds

Oxygen-depletedzone

Closedbeach

CitiesToxic metals and oil from streets and parking lots pollute waters;

IndustryNitrogen oxidesfrom autos andsmokestacks,toxic chemicals,and heavy metals in effluents flow into bays and estuaries.

Closedshellfish beds

Pacific garbage patch

• largest estuary in U.S.

• severely degraded by water pollution from 6 states

• deposition of air pollutants

© Brooks/Cole Publishing Company / ITP

Example: Chesapeake Bay

What is hypoxia? Where else do we see it in the U.S.?

The Gulf of Mexico Dead Zone