Transcript Ch 4-3 Envir

Chapter 4
Land, Water and Air
Resources
Section 3
Water Pollution and Solutions
Notes 4-3
Limited Supply
 Most water on Earth is salty
 97%
 Only 3% of all water is usable (fresh)
 2/3 of all fresh water is in the form of ice
 Groundwater is another form of fresh
water
 Water stored in layers of soil and rock under
the surface of the earth
Renewing Supply
 Fresh water is renewable
 Water cycle continuously renews fresh water
 When water evaporates, it leaves the pollution
behind
 Water is fresh once it is in the form of water
vapor
 However, water can re-pollute itself if it falls
through pollution
 Forms acid rain
Water Shortages
 Occur when people use water fast than it
can be renewed
 Happens often in a drought
 Can also make fresh water, for places that
do not have enough rain fall to produce
the water that they need, by taking salt out
of sea water
Water Pollution
 Any change in water that has a harmful
effect on people or other living things
 Iron or copper: make drink and bathing
unpleasant
 Mercury or benzene: cause sickness or death
 Most pollution is caused by human activities
 Sewage: water and human waste washed
down sinks, toilets and showers
 Can make people very ill
Water Pollution
 Agricultural Waste:
 Animals waste and farm chemicals
 Fertilizers: chemicals that provide nutrients to
help crops grow better
 Pesticides: chemicals that kill crop-destroying
organisms
 These can build up to harmful concentrations
Water Pollution
 Industry and Mining:
 Chemical plants, paper and textile mills, and
factories use metal that can pollute.
 Metal can harm ecosystems: people, animals,
plants and environment
 Sediments:
 Tiny particles of rock, silt and sand
 Can be washed into areas where it covers
food, nesting sites and eggs of organisms
Water Pollution
 Oil and Gasoline:
 Oil spills kill fish, birds and other life in ocean
areas
 Gasoline can leak out of underground tanks
and get into groundwater and drinking water
 Heat:
 Power plants sometimes put hot water used
to cool devices back into the environment too
soon
 Causes plants and animals to die
 Cooling towers are now used to keep this
from happening
Cleaning Up the Water
 To reduce water pollution:
1. Treat wastes so they are less harmful
2. Find substitutes for pollutants
 Sewage Treatment
 Primary Treatment: removes solid materials
from wastewater
 Water passes through filters
 Solids are held in tanks and particles settle out
Cleaning Up the Water
 Secondary Treatment: bacteria break down solid
wastes
 Water is treated with chlorine to kill disease causing
organisms
 Arcata, CA
 Wastewater flows into ponds with algae
 Algae breaks down sewage
 Water moves to marshes with cattails and bulrushes to
clean the water
 Areas are also for habitats for fish and birds
 Also areas for bike riding and trails for recreation
Cleaning Up the Water
 Oil and Gasoline
 Oil spills can be cleaned up with bacteria
 Bacteria eat the oil and reproduce as long as there is
food
 They die off as soon as their food disappears
 Big oil spills affect the wildlife before the bacteria can
restore the ecosystem
 Gasoline spills are hard to clean up
 Soil can be removed
 However, if gasoline reaches the groundwater…much
worse!
 Water has to be pumped out and cleaned
 Then it can be put back into the ground
Cleaning Up the Water
 Industrial Chemicals
 Industries can recycle their wastes
 They save money and reduce pollution
 Industries can change how they produce their product
 Use less water or create less harmful wastes
 Farming Chemicals
 Finding alternatives to pesticides and fertilizers
 DDT (dichloro-diphenyl-trichloroethane)
 1972 DDT usage was stopped
 Today it is labeled as a probable human carcinogen
 Stays in an organism for a long time
What can you do?
 Little changes can make a big difference
 Don’t pour harsh chemicals down the drain
 Don’t dump them in the grass
 Paint thinner
 Motor oil
 Garden chemicals
 Use environmentally friendly cleaning supplies