Chapter 2: POLLUTION AND CONTROL



Introduction

An average human needs 12-15 times more air than food.


Particulate matter of size 2.5 microns or less causes greatest harm to humans. These can’t be removed even by electrostatic precipitators which remove 99% of all particulate matter from exhaust of thermal power plants.


Even for cars that emit toxic fumes, the presence of catalytic converters is essential. In these converters metals like platinum – palladium, rhodium are present. These convert the un-burnt hydrocarbons, carbon monoxide, and nitric oxide into water, carbon dioxide and nitrogen gas.




But unleaded petrol must be used otherwise the catalyst in the converters are inactivated by lead.

Triethyl lead is used as an anti knock agent for smooth running of vehicles. The lead if inhaled then causes damage to kidney, liver and development of red blood cells.


In cities, clouded high rise buildings trap the warm air and thus raise the temperature of the cities. These creates Urban Heat Islands.




                                                      Fig 1: Urban heating effect


Iron and steel industries produce blast furnace slag, steel melting slag and fly ash. This is non biodegradable and now it’s used by cement industry to make blended cement.




Global warming is the rise of temperature of the earth due to absorption of long wave terrestrial radiation by the green house gases. 3°c increase can lead to decrease in precipitation by 10%. It will cause polar icecaps to melt and flood the coastal areas. Coastal ecosystems like swamps and marshes will be damaged. Rainfall may fluctuate and grains may mature early leading to smaller grain size and lower yield. Hurricanes, tornadoes may increase in intensity. Temperate areas might lose soil moisture lowering agricultural productivity.


Due to rise in water temperatures the smaller fishes are migrating to other areas and the bigger fishes are affected. Big fishes may become extinct affecting marine ecosystem and livelihoods of fishermen.


The UV radiations from the sun are of three categories – A, B, C. UV- C radiations are the most damaging to humans.


Air Pollution - China and India



Although the deaths recorded due to outdoor air pollution is higher in China than India. The rate of growth of air pollution deaths and the deaths per lakh population is higher in India. So more people die here due to outdoor air pollution.

The indoor air pollution deaths mostly due to cooking from fossil fuels is also higher in India than China. The measures taken by India to reduce indoor air pollution related deaths like promotion of LPG and CNG for cooking has reduced the number of deaths.

However the deaths due to outdoor air pollution have only increased due to increase in cars, and power plants. India had set emission standard norms for power plants in 2015 but not 1 has implemented them fully.

Water pollution and control:




When sewage water is released in the rivers the microbes use up more oxygen for degradation as it’s oxygen requiring process. This increases the biochemical oxygen demand. The oxygen isn’t available for aquatic animals and plants and hence they die.


When excess nutrients are present in soil the planktonic organisms bloom and hence the competition for fishes and other plants increase. This leads to algal bloom and fish mortality. The water quality also deteriorates. This is called Accelerated Eutrophication.




An algal weed named water hyacinth is known as the terror of Bengal for its fast growing rate.


Limit of photosynthesis i.e. Penetration of sunlight below the ocean surface is 125m.



                                                            Fig 2: Light and ocean


Thermal pollution is caused when the heated water released by thermal, nuclear, chemical industries is released into river, seas and oceans. The aquatic animals are suited to a constant temperature and when the temperature increases above a range it affects them. The hot water increases their metabolism and affects their growth.


Mosquito borne diseases related with water:



  1. Malaria – female anopheles mosquito
  2. Filariasis – Culex mosquito
  3. Dengue – Aedes Aeqypti


International drinking standards for water:



  1. Fluoride: the concentration of fluorine in water should be 1 ppm. This converts the hydroxyapatite on the surface of the teeth into flourapatite thus hardening them.
  2. Lead: the concentration should e 50 ppm otherwise it will damage health.
  3. Sulphate: <500 ppm otherwise it has laxative effect.
  4. Nitrate: <50 ppm otherwise causes blue baby syndrome or Methemoglobinemia.
  5. Minamata disease caused due to mercury poisoning as high quantity of mercury was released in water.
  6. Itai – Itai disease is caused by cadmium poisoning. Lead causes displexia.
  7. Black lung disease or pneumoconiosis is due to deposits of coal in lungs of miners.


85% of Indian population depends on ground water for its domestic consumption.


Radiation:


It is a form of energy travelling through space.




Non ionizing: these are electro-magnetic waves with long wavelengths that have energy to excite the electrons to vibrate faster but not to ionize them.


Ionizing: These are of short wavelengths and cause ionizing of water molecules. These break the chemical bonds and damage living tissues.


Radiation damage can be somatic or genetic. Somatic doesn’t affect genes or mutation. Genetic affects genes resulting in birth defects. These are passed on to the next generation.



Quiz

Score more than 80% marks and move ahead else stay back and read again!