Water Pollution

Water Pollution Overview

Sewage dumping

Water Pollution Overview

Ocean Pollution

Water Pollution Overview

Urban Water Pollution

Water Pollution Overview

Urban Runoff

Water Pollution Overview

Eutrophication

Water Pollution Overview

Agricultural Runoff

Water Pollution Overview

Acid Mine Drainage

Water Pollution Overview

Unsafe drinking water and disease

Water Pollution Overview

Erosion and sediment deposition

Water Pollution Overview

Oil Spills

What is water pollution?

• Any physical, biological or chemical change in water quality that adversely affects living organisms or makes the water unsuitable for desired uses

• Review:– point sources– nonpoint sources

• Make sure you know examples of these!

Types of Water Pollution(fresh water mainly)

• Infectious agents• Oxygen demanding wastes• Plant nutrients and Eutrophication• Toxic inorganic materials• Organic chemicals• Sediment and suspended solids• Thermal pollution/ thermal shock

1. Infectious Agents

Safe to Swim?

Infectious Agents• Most serious water pollutants in terms of human

health• Ex. typhoid, cholera, dysentery, polio, hepatitis• 25,000,000 deaths each year (2/3 of child deaths,

80% of sickness in developing countries)• Comes from untreated human wastes and animal

wastes• 2.5 billion people lack sanitation (more lack clean

water)

How to test for unsafe water

• Water that is unsafe to drink usually has many types of bacteria in it.

• Instead of testing for all types, usually the common coliform bacteria is measured

• one colony of bacteria per 100ml is considered unsafe to drink by WHO standards

• 200 colonies per 100 ml is considered unsafe to swim by EPA standards.

2. Oxygen-demanding Wastes

Oxygen-demanding Wastes• Healthy water has a high level of dissolved oxygen

(> 8ppm)• Oxygen-poor water (<2ppm) only supports

detritivores• Oxygen is added to the water by diffusion from air

(affect of temperature) and photosynthesis• Oxygen is removed by respirati on of plants and

animals• The addition of sewage and wastes stimulates

oxygen consumption by detritivores

Measuring Oxygen Content

• BOD: Biological Oxygen Demand– this measures the demand for oxygen that the

detritivores place on the system– how much O2 is used by organisms over a 5

day period• DO: Dissolved oxygen content

– how much oxygen is dissolved in the water– is affected by temperature and aeration

Water Quality: DO

“Oxygen Sag”•The oxygen sag is the pattern of dissolved oxygen in a stream that is being dumped into

•The pattern of organisms is determined by the DO content

•Know the different types of organisms and where they occur

•The length of the oxygen sag will depend upon how fast the stream is flowing, and how turbid it is

Oxygen Sag cont.

3. Plant Nutrients and Eutrophication

Eutrophication

• Water ecosystems (lakes) are usually limited by the amount of nutrients in them.

• Over succession, lakes gradually increase in nutrients and productivity

• Humans artificially increase the amount of nutrients in lakes through fertilizers, run-off

• The increase in nutrients leads to a series of stems culminating in eutrophication

Steps of Eutrophication• Nutrients are added to water• Increase in nutrients cause an algae bloom• As the algae bloom progresses, the algae

begin to die, and organic material accumulates on the bottom of the lake

• This material supports a boom in the decomposer populations

• The decomposers rapidly rob the lake of its oxygen, suffocating most other organisms in the process

What Eutrophication Looks Like

4. Toxic Inorganic materials

Toxic Inorganic materials

• Heavy metals:– mercury, lead, cadmium and nickel– lead pipes– gold mining– mining wastes, mine drainage– tin on boat bottoms

Nonmetallic salts

• Occurs in desert soils• As water evaporates, high levels of toxins

are left behind• Also from road runoff• ex. selenium and arsenic• also table salt in very high concentrations• ex. Salton Sea

Acids and Bases

• Produced during leather tanning, metal smelting, plating, petroleum distillation and organic chemical formation

• Coal mining produced sulfuric acid ACID MINE DRAINAGE

• Acid rain (HNO3 and H2SO4)

5. Organic Chemicals

Organic Chemicals

• Pesticides, oils, plastics, pharmaceuticals, pigments, detergents, cleaning solutions, and paints

• DDT, etc. • Stringfellow Site

6. Sediment and suspended solids

Sediment and suspended solids• Largest pollutant by volume in most parts of

world• Erosion has increased sediment levels• 25 billion metric tons of topsoil from runoff

and erosion• 50 billion from grazing, construction etc.• fills reservoirs, fills shipping channels, less

suitable for life, recreation• Small levels of sediment are good

How sediments can be harmful

7. Thermal Pollution

Thermal Pollution• Raising or lowering temperature from

normal levels• Water temps are usually stable so organisms

are poorly adapted to rapid change• oxygen solubility decreases as temperature

increases• most happens in industrial cooling• can be good for raising species that

wouldn’t be there otherwise• but can be harmful--> manatees

Groundwater pollution

Relative Polluters of Rivers

Types of Ocean Pollution• 1. Red tides• Storms bring nutrient-rich runoff to the oceans• these nutrients cause a bloom in phytoplankton in

the oceans

Types of Ocean Pollution

• 2. trash

Types of Ocean Pollution

3. OilOil spills have occurred in most of the shipping lanes in the world (as of 1985)Large effects on sea surface critters

Spain - 2003

Types of Ocean Pollution

• 4. Sewer waste/runoff• many countries of the world (inc. U.S.)

dump their waste into ocean• results in diseases, abnormalities in

organisms

Water Pollution Solutions

Water Pollution Solutions• Ban or regulate phosphate detergents

– advanced water treatment to remove them• Control agricultural runoff

– revegetation, wetlands, riparian, reduce water runs off of farms, reclaim water

• Control urban runoff– golf courses, lawns, pets etc.; reduce use

• Control sediments and acids from mines– revegetation and sediment traps (ponds)

• Control streambank erosion and protect wetlands– protect and revegetate

How is human waste controlled?

• Municipal Treatment– Primary– Secondary– (Tertiary)

• Private Treatment– septic tanks

Sewage Treatment

Treatment of Human Waste

• Primary treatment: taking out solids– grating (removes debris)– moving screen (takes out smaller pieces)– grit tank (sand and gravel settle)– primary sedimentation tank (sludge settles)

Treatment of Human Waste

• Secondary treatment: biological degradation– aeration tank (or filter bed, sewage lagoon)– fluid is mixed with a bacteria rich slurry– air is pumped in which promotes bacterial growth– bacteria and sludge is removed off the bottom

(some is returned to inoculate the aeration tanks)– water is sometimes chlorinated to kill bacteria,

then released

Treatment of Human Waste• Tertiary Treatment: removal of plant nutrients

– removal of nitrates, phosphates and other nutrients which can cause algal blooms

– this is accomplished by passage through a wetland or lagoon

• Sewage treatment works well except:– water in storm drains gets no treatment– during storms, raw sewage is dumped– treated water still has environmental effects

Septic Tanks

• A house-by-house alternative to sewer systems

• Water is pumped into a tank– oils rise to top, solids to bottom– middle water is pumped into a series of pipes

where it can evaporate and be worked on by bacteria

• Works well if maintained, but can leak into ground water

Clean Water Acts

• Federal Water Pollution Control Act– Clean Water Act of 1972 (amended 1977)– goal was to make all U.S. surface waters safe

for fishing and swimming by 1983 and restores and maintain the chemical, physical and biological integrity of the nations waters

– established controls for each major type of pollutant

– provides billions of dollars for sewage treatment plants

Clean Water Acts

• Safe Drinking Water Act 1974– established minimum safe levels for drinking

water• Superfund established 1980• Water Quality Act 1987

– established a national policy for nonpoint sources of pollution

• 1995 - discharges trading policy established

Is the legislation working? Some good news

• Between 1972 and 1992 the amount of rivers and lakes that are fishable and swimable has increased from 36% to 62%

• Average phosphorous levels have dropped from .12ppm to .079ppm

• DDT has dropped from 1.2ppm to .196ppm• But, 44% of lakes, 37% of rivers and 32% of

estuaries are unsafe for fishing and swimming so there is more to do.