WaterPollution

pollutants, sources and effects
Point and nonpoint sources
Is the water safe to drink?

and animal waste
Oxygen-Demanding Waste
Organic debris & waste + aerobic bacteria
Source: Sewage, feedlots, paper-mills, food processing
Inorganic Chemicals
Acids, Metals, Salts
Sources: Surface runoff, Industrial effluent, household cleansers
Radioactive Materials
Iodine, radon, uranium, cesium, thorium
Source: Coal & Nuclear Power plants, mining, weapons production, natural

Plant Nutrients
Nitrates, Phosphates,
Source: Sewage, manure, agricultural and landscaping runoff
Organic Chemicals
Oil, Gasoline, Plastics, Pesticides, Solvents, detergents
Sources: Industrial effluent, Household cleansers, runoff from farms and yards
Eroded Sediment
Soil, Silt
Heat/Thermal Pollution
Source: Power plants, Industrial

water quality
Recharge groundwater
Fertile soils
Nearby rivers for use and recreation
Flatlands for urbanization and farming

and water diversion
Bangladesh

roots stabilize soil and aid water flow

Vegetation releases
water slowly and
reduces flooding

Forested Hillside

Flooding After Deforestation of a Hillside

topsoil

Gullies and
landslides

Heavy rain leaches nutrients from soil and erodes topsoil

Rapid runoff
causes flooding

After Deforestation

Roads
destabilize
hillsides

Agriculture land
is flooded and
silted up

Silt from erosion blocks rivers and
reservoirs and causes flooding downstream

Flooding After Deforestation of a Hillside

approach

little flow hinder rapid dilution of pollutants
Lakes more vulnerable to pollutants than streams
How pollutants enter lakes
Eutrophication: causes and effects
Oligotrophic and eutrophic lakes
Cultural eutrophication
Preventing or removing eutrophication

and dispersion
Consequences of lower dissolved oxygen
Fewer bacteria to decompose wastes
Cooler temperatures: slow down chemical reactions
“Degradable” and nondegradable wastes in groundwater

casing

Hazardous waste injection well

Pesticides
and fertilizers

Gasoline station

Buried gasoline and solvent tank

Sewer

Cesspool septic tank

De-icing road salt

Unconfined freshwater aquifer

Confined freshwater aquifer

Water pumping well

Landfill

Polluted air

Groundwater Pollution

including fuel leaks
Arsenic
Protecting groundwater: Prevention is best

cheapest, easiest, and most effective method but is still being developed)

Find substitutes for toxic chemicals

Keep toxic chemicals out of the environment

Install monitoring wells near
landfills and underground tanks

Require leak detectors on underground tanks

Ban hazardous waste disposal
in landfills and injection wells

Inject microorganisms to clean up contamination (less expensive but still costly)

Store harmful liquids in aboveground tanks with leak detection and collection systems

Prevention

Cleanup

Pump to surface, clean, and return to aquifer (very expensive)

Solutions

Groundwater Pollution

Preventing and Cleaning Up Pollution in Groundwater

in oceans
Ocean dumping controversies

flow into bays and estuaries.

Cities
Toxic metals and
oil from streets and
parking lots pollute
waters; sewage
adds nitrogen and
phosphorus.

Urban sprawl
Bacteria and viruses from sewers and septic tanks contaminate shellfish beds and close beaches; runoff of fertilization from lawns adds nitrogen and phosphorus.

Construction sites
Sediments are washed into waterways,
choking fish and plants, clouding
waters, and blocking sunlight.

Farms
Run off of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.

Red tides
Excess nitrogen causes explosive growth of toxic microscopic algae, poisoning fish and marine mammals.

Healthy zone
Clear, oxygen-rich waters
promote growth of plankton
and sea grasses, and support fish.

Toxic sediments
Chemicals and toxic metals
contaminate shellfish beds,
kill spawning fish, and
accumulate in the tissues
of bottom feeders.

Closed
shellfish beds

Closed
beach

Oxygen-depleted
zone

Coastal Water Pollution

Oxygen-depleted zone
Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat.

blowouts
Exxon Valdez
Volatile hydrocarbons kill larvae
Tar-like globs coat birds and marine mammals
Oil destroys insulation and buoyancy
Heavy oil sinks and kills bottom organisms
Coral reefs die
Slow recovery
Oil slicks ruin beaches
Limited effectiveness of clean up methods

in coastal waters

Reduce input of toxic pollutants

Separate sewage and storm lines

Regulate coastal development

Recycle used oil

Require double hulls for oil tankers

Require at least secondary
treatment of coastal sewage

Use wetlands, solar-aquatic, or
other methods to treat sewage

Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful byproducts
(still under development)

Protect sensitive areas from development, oil drilling, and oil shipping

Ban ocean dumping of sludge and hazardous dredged material

Improve oil-spill cleanup
capabilities

Solutions

Coastal Water Pollution

Preventing and Cleaning Up Pollution in Coastal Waters

fertilizer use
Use plant buffer zones around fields
Integrated pest management: Only use pesticides when necessary
Use plant buffers around animal feedlots
Keep feedlots away from slopes, surface water and flood zones

sewage treatment
Secondary (biological) sewage treatment
Urban sewage treatment (Clean Water Act)
Sewage treatment facilities in many cities fail to meet federal standards
Bleaching and disinfection
Disinfectants: chlorine, ozone, and ultraviolet radiation

(for cleanout)

Drain
field

Vent pipe

Nonperforated pipe

Gravel or
crushed
stone

tank

Chlorine
disinfection tank

Sludge

Sludge digester

Activated sludge

Air pump

(kills bacteria)

To river, lake,
or ocean

Sludge drying bed

Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland

Primary

Secondary

nature to treat sewage
Using wetlands to treat sewage

and developers

State and local officials want more discretion

developing countries
Bottled water