Water Pollution. Some of the stuff that it dissolves / suspends is good for us Others, not so good.
29
Water Pollution
Transcript of Water Pollution. Some of the stuff that it dissolves / suspends is good for us Others, not so good.
Water Pollution
Some of the stuff that it dissolves / suspends is good for us
Others, not so good
Can you name 5 things that dissolve in water?
Know of any 2 that can be called ‘pollutants’ – those dangerous to life ?
If we drink polluted water, we can get sick
Figure out some pollutants
C TS K
+ + _ _ _ _ _ _ _
Led ZeppelinBlack Sabbath
Deep PurpleIron Maiden _ _ _ _ _ _ _ _ _ _
+ _ _ _ _ _ _ _GH
Sounds like + _ _ _ _ _ _ _ _
Clue: toothpaste
Figure out some pollutants
C TS K
+ + ARSENIC
Led ZeppelinBlack Sabbath
Deep PurpleIron Maiden HEAVY METAL
+ NITRATEGH
Sounds like + FLUORIDE
Clue: toothpaste
How do we know that water is polluted?
Sometimes it stinks……but not always
Sometimes polluted water changes colour…..but not always
Sometimes it tastes different ……..but not always
How do we know that water is polluted?
Water pollution can be confirmed only by testing it in a lab
Sources of water pollution are generally grouped into two categories
Non-point source of pollution:
Contamination gathered by water over a large area.
Point-source of pollution:
Contaminants enter a waterway at a discrete point
Water can get polluted naturally
When water seeps into the ground, it absorbs different substances depending on the type of soil and rock that it flows through.
Water can get polluted naturally
Some of these substances (arsenic, iron, fluoride, etc.) can be harmful to our health.
Natural pollution is a non-point source of pollution
Arsenic
Fluoride
Natural pollution can introduce chemicals that collect in our bodies. Over time this can cause chronic problems and even
life – threatening diseases.
In groundwater
In groundwater
Does Man Pollute Water?
“ If you had a bottle of life-preserving fluid on which your life depended,
would you pour into it all your sewage and rubbish, along with any other
poisonous chemicals you could find? And yet, that is exactly what we are
doing to our water supply – all over the world.”
This is what a young person like you has to say:
The various ways in which man pollutes water Untreated or inadequately treated municipal sewage
Yamuna, when it leaves Delhi, resembles a sewer full of the city’s wastes. A few hundred kms downstream is Agra, where
this ‘sewer’ is the main municipal drinking water source.
YUCK!
! eutrophication
An example of Point source of pollution
Reaches ground water bodies
Untreated sewage seeps in and contaminates groundwater aquifers
Such aquifers show a higher than acceptable level of nitrate content
The various ways in which man pollutes water Untreated or inadequately treated municipal sewage
An example of Point source of pollution
The various ways in which man pollutes water
When garbage is dumped in a landfill, toxic chemicals leach into the soil and groundwater.
Dumping garbage in surface water bodies
Over 10 million people bathe in the Ganga daily!
The various ways in which man pollutes water
Washing and bathing introduces phosphates and other chemicals into water
The various ways in which man pollutes water
Agriculture is a major source of groundwater
contamination.
AgricultureAn example of Non- Point source of pollution
dissolve in irrigation water or rainwater.
They contaminate surface water and groundwater with pollutants like
nitrates, phosphates, and non degradable synthetic organic pollutants.
The various ways in which man pollutes water
Industry
Agro industries (sugar, food processing, pulp and paper, distilleries) – their wastes have high concentration of dissolved organic matter.
Chemical Industries – If their wastes are not treated properly, the chemicals can destroy our soil and water resources.
Petroleum refining – water used in the process needs to be separated from all the oil before releasing it into nature……but is that done?
An example of Point source of pollution
Minamata disease
The various ways in which man pollutes water
Industry
Thermal power plants – water is needed to cool the process.
The water gets hot and when it’s released into a larger water body, it upsets the ecology by modifying the delicate temperature balance.
This is called ‘Thermal pollution’
An example of Point source of pollution
Effluent treatment plants
Liquid wastes from an industry are treated in effluent treatment plants.
Large industries have in-house effluent treatment plants.
It’s expensive for small industries to have such plants of their own.
In some industrial estates, a group of small industries have a common effluent treatment plant.
A RE-CAP
Water can be polluted by man
Water can be polluted naturally
Sewage in our water bodies Garbage dumps Washing and bathing Pesticides and fertilizers Industries
Divide the class into 5 teams
Draw as many dashes as in the name of a water pollutant or a pollution cause.
Team A starts. They guess a letter. The teacher puts in the letter at the correct place, if it is there in that name.
Else, the letter is written down on one side.
A maximum of 10 wrong guesses are allowed.
The team gets as many points as letters on the side (maximum of 10).
The team with the lowest number of points wins.
Hangman
Eutrophication (pronounced as you-tro-fi-kay-shun)
When wastes with high organic content (such as sewage wastes) are dumped into a water body like a lake or pond, eutrophication can occur, killing all life in the water body.
Organic wastes are rich in nutrients (nitrates and phosphates)
They stimulate excessive plant growth – especially weedy species
Eutrophication
On dying, the plants further add to the organic waste in water.
Microorganisms that decompose the organic material in water use up a lot of dissolved oxygen.
This depletes the available oxygen in the water and upsets the ecological balance, since fish and other life forms perish without adequate oxygen.
Eventually all the oxygen is used up.
Eutrophication
Anaerobic organisms then attack the organic wastes, releasing gases such as methane and hydrogen sulphide.
The result is a foul smelling, waste filled body of water, quite like many of the lakes in India.
These water bodies are also natural groundwater recharge systems and their contamination also leads to groundwater pollution.
Minamata disease Industrial wastewater from the Chisso corporation (manufacturing fertilizers and other chemicals) was released into the Minamata Bay in Japan.
The waste water was rich in methyl mercury.
Mercury content in shellfish in that region increased.
People ate the shellfish and the cats ate the leftovers.
Strange things started to happen – cats had convulsions and died, crows fell from the sky, dead fish floated.
Young children had convulsions and difficulty in walking and speaking. People died. Investigation showed organic mercury poisoning affecting the nervous system.
First discovered in 1956.
Lawsuits and claims continue till today.
