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Water Pollution (Water Resources: Water Properties (Melting and Boiling…
Water Pollution
Water Resources: Water Properties
Dipolar
Capillary action
Density
Expands when freezes, Ice floats, thermal stratification
Melting and Boiling points
Exist as a gas
all 3 states in normal ranges of temperature
Specific Heat
Very high heat capacity: Long to heat and cool
Heat of vaporization
Need a LOT of energy vaporize
solvent
Effective medium from transporting dissolves
nutrient's
Greenhouse effect
Absorbs solar energy, infrared radiation
WATER RESOURCES: WATER USAGE
10% of annual runoff is withdrawn for human use
water supplies isn’t a problem?
Some areas have a lot of water
Some have very little water
Some have sufficient precipitation averages, however chaotic
variations year on year
Distribution of water availability to population density not a good
match!
Graph Pg 5
Function of the rising demands for water:
Increasing populations
Increasing developmental needs
Water CONTROLLED BY ANOTHER COUNTRY
Egypt needs 97%, Ethiopia controls flow of Nile
Turkey, Syria and Iraq share Euphrates
Bangladesh replies on Ganges,
controlled by India
Israel and Jordan share Jordan River
knock on effect
Upstream pollution in one country can
potentially cause a epidemic in another.
Cooling water for power plants effectively returned “unpolluted” back into
water cycle
Thermal pollution
Graph Page 7
WATER POLLUTANTS: PATHOGENS
Contaminated water known to be responsible for many contagious diseases
Pathogens: Disease causing organisms that grow and multiply host
Infection:
Bacteria
Cholera
Dysentery
Typhoid
Viruses
Hepatitis
Parasitic worms
Bilharzia
Waterborne: Cholera, ingested
Water washed: Scabia, cleanliness
Water based: Bilharzia, contact
Water related: Malaria, carries host
WATER POLLUTANTS: OXYGEN DEMANDING
WASTES
Quality of water measure: DO (Dissolved Oxygen content)
8 to 15mg per litre
Fish need between 5mg/l to 8mg/l
Oxygen demanding wastes use the available DO and decrease available concentrations
Lead to aquatic life being threatened or killed
Undesirable odours, tastes and colours
COD: Chemical Oxygen Demand
Required O2 to chemically oxidize waster
BOD: Biological Oxygen Demand
Required O2 by microorganisms to degrade the waste
WATER POLLUTANTS: NUTRIENTS
nitrogen, phosphorus, carbon, sulphur and calcium
Pollutants where their concentrations are HIGH enough to allow EXCESS
growth of aquatic plants, specifically ALGAE
Blooms of algae
Die and decompose
Remove DO from water during decomposition
Add colour, turbidity, odours and tastes to water
Eutrophication
Nutrient enrichment
Algal growth rates controlled by:
Nitrogen
Phosphorus
Additional run-off
Unbalance
WATER RESOURCES: HYDROLOGIC CYCLE
97%: Oceans
Salts render it useless as a source of water
desalination
Countries do rely on this
Very very expensive
Small scale
Desalination is a process that takes away mineral components from saline water.
sun
Evaporation from wet surfaces
Transpiration from leaves of plants
Energy equivalent to approx. 4000 times the rate we use energy to power
our societies
WATER RESOURCES: HYDROLOGIC CYCLE
Graph pg 4
