Biology

POLLUTION

What is pollution?

Effects of Pollution on Human Beings and other Organisms

Pollution

  • This is the introduction of foreign material, poisonous compounds and excess nutrients or energy to the environment in harmful proportions.
  • Any such substance is called a pollutant. Effects and Control of causes of Pollutants in Air, Water and Soil
  • Industrialisation and urbanisation are the main causes of pollution.
  • As human beings exploit natural resources the delicate balance in the biosphere gets disturbed.
  • The disturbance leads to the creation of conditions that are un-favourable to humans and other organisms.

Sources of Pollutants

  • Motor vehicles release carbon (II) oxide, sulphur (IV) oxide, and nitrogen oxides and hydrocarbons.
  • Agricultural chemicals, fertilizers and pesticides.
  • Factories, manufacturing and metal processing industries.
  • They release toxic substances and gases as well as synthetic compounds that are bio-undegradable.
  • They release solid particles or droplets of poisonous substances e.g. arsenic, beryllium, lead and cadmium.
  • Radioactive waste: Leakages from nuclear power stations and testing sites release radioactive elements like strontium-90 which can eventually reach man through the food chain.
  • Domestic waste and sewage are released raw into water bodies.
  • Oil spills from accidents in the seas and leakage of oil tankers as well as from offshore drilling and storage and processing.
See also  WATER POLLUTION

Water Pollution.

  • In most cases, chex, pical wastes from industries are discharged into water.
  • Toxic chemicals such as mercury compounds may be ingested by organisms.
  • Insecticides like DDT, and weed¬killers eventually get into the water and contaminate it.
  • Oil and detergents also pollute water.
  • Excess nitrates and phosphates from sewage and fertilisers cause overgrowth of algae and bacteria in water.
  • This is called eutrophication.
  • As a result there is insufficient oxygen which causes the deaths of animals in the water.

Air pollution:

  • Smoke from industries and motor vehicles contains poisonous chemicals like carbon (II) oxide, carbon (IV) oxide, sulphur (IV) oxide and oxides of nitrogen.
  • When sulphur (IV) oxide and oxides of nitrogen dissolve in rain, they fall as acid rain.
  • Accumulation of carbon (IV) oxide in the atmosphere causes the infrared light to be confined within the atmosphere, the earth’s temperature rises.
  • This is called the greenhouse effect.
  • Carbon particles in smoke coat the leaves of plants and hinder gaseous exchange and photosynthesis.
  • The particles also form smog in the air.
  • Lead compounds are from vehicle exhaust pipes.
  • All these have negative effects on man and the environment.
See also  PRACTICAL ACTIVITIES TO DEMONSTRATE CONTINUOUS VARIATIONS

Soil/Land pollution:

  • Plastics and other man-made materials are biologically non-degradable i.e they are not acted upon by micro-organisms.
  • Scrap metal and slag from mines also pollute land.
  • Failure to rehabilitate mines and quarries also pollute land.

Effects of Pollutants to Humans and other organisms

  • Chemical pollutants e.g. nitrogen oxides, fluorides, mercury and lead cause physiological and metabolic disorders to humans and domestic animals.
  • Some hydrocarbons as well as radioactive pollutants acts as mutagens (cause mutations) and carcinogens induce cancer.
  • Radioactive pollutants like strontium, caesium and lithium are absorbed into body surface and cause harm to bone marrow and the thyroid gland.
  • Communicable diseases like cholera are spread through water polluted with sewage.
  • Thermal pollution result in death of some fish due to decreased oxygen in the water.
  • Oil spills disrupt normal functioning of coastal ecosystems.
  • Birds that eat fish die due to inability to fly as feathers get covered by oil.
  • Molluscs and crustaceans on rocky shores also die.

Control of Air Pollution

  • Use of lead-free petrol and low sulphur diesel in vehicles.
  • Use of smokeless fuels e.g. electricity or solar.
  • Filtration of waste gases to remove harmful gases.
  • Liquid dissolution of waste gases.
  • Factories are subjected to thorough audits to ensure that they do not pollute the environment.
  • Factories should be erected far away from residential areas.
  • Reduce volume or intensity of sound.
  • Use of ear muffs.
  • Vehicle exhaust systems should be fitted with catalytic oxidisers.
  • Regular servicing of vehicles to ensure complete combustion of fuel.
See also  ACTIVE TRANSPORT

Water Pollution

  • Treatment of sewage.
  • Treatment of industrial waste before discharge into water.
  • Use of controlled amounts of agrochemicals.
  • Organic farming and biological control.
  • Avoid spillage of oils and other chemicals into water.
  • Good water management.
  • Stiff penalties for oil spillage.
  • Use of Pseudomonas bacteria that naturally feed on oil and break it up.

Soil Pollution

  • Addition of lime to farms to counteract the effect of agrochemicals.
  • Recycling of solid waste.
  • Compacting and incineration of solid waste.
  • Use of biodegradable materials and chemicals.
  • Good soil management to avoid soil erosion.

See also

HYDROPHYTES (WATER PLANTS)

POPULATION ESTIMATION METHODS

FOOD CHAINS

THE ECOSYSTEM

ECOLOGY

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