Human activities are responsible for the disturbance of balanced system of an environment. Increasing human population produces a strain on the resources and availability of energy and materials, which deplete. The process of urbanization and industrialization, use of chemical fertilizers and pesticides, hasty approaches to the formulation of developmental projects particularly hydro-electric and those on tourism, road, building, mining and disposal of waste materials are the main developmental activities of man.
All these activities introduce many unwanted substances in the environment and disturb the balanced system of the environment. This is known as ecological balance.
The major ecological imbalances are greenhouse effects, depletion of ozone layer and acid rain.
The greenhouse effect refers to circumstances where the short wavelengths of visible light from the sun pass through a transparent medium (i.e. envelope of gases CO, CO2, SO2, etc.) and are absorbed, but the longer wavelength of the infrared radiation from the heated objects are unable to pass through that medium and are trapped causing more heating and a higher resultant temperature.
The causes of greenhouse effect are as follows;
Due to deforestation.
Due to population growth, the excessive amount of CO2 is being deposited in the atmosphere through furnaces of power plants, automobiles, factories, etc.
Industries which are involved in cement production, fertilizers, coal mining, etc. produce harmful greenhouse gas.
Nitrous oxide is one of the greenhouse gas that is used in fertilizer and contributes to the greenhouse effect.
It results in the increase in temperature of the earth as a whole causing global warming.
The rise in temperature result increases in sea level due to the melting of polar caps.
Warming up of the atmosphere causes natural calamities like flood, hurricanes, and cyclones nearby the oceans.
Higher atmospheric temperature increase evaporation of water from the farms reducing crop yield.
Monsoon may even stop altogether or rainfall may be altered.
Depletion of ozone layer
The ozone layer is a deep layer in earth’s atmosphere that contains ozone which is a naturally occurring molecule containing three oxygen atoms. An essential property of ozone molecule is its ability to block solar radiations of wavelengths less than 290 nanometers from reaching Earth’s surface. In this process, it also absorbs ultraviolet radiations that are dangerous for most living beings.
Chloro Fluro Carbon (CFC) gas released by industry releases chlorine-containing chemicals that react with ozone and causes damage to it.
Volcanic eruption, burning of large forests and savannahs, jet planes also contribute to the depletion of ozone.
In the stratosphere, the CFCl3 is broken down into chloride atoms in the presence of UV radiation. Each chloride atom reacts with more than 10,000 atoms of O3 converting into O2. Here, produced chlorine atom can destroy other molecules of O3.
Due to more UV radiations entering, it increases the earth’s temperature that can lead to the failure of rainfall.
Harmful UV radiations may cause skin cancer.
Higher UV radiation reduces the photosynthesis thus, reducing the productivity of crops.
UV radiation results in the number of phytoplankton and zooplanktons and thus, harms fish and other aquatic life.
Acid rain is a rain or any other form of precipitation that is usually acidic, meaning that it have the higher number of hydrogen ions (low pH). Normal or unpolluted rain has a pH of 5.6%, the acidity is due to the presence of CO2 in the air. But acid rain has a pH value of 4 to 4.5 that is due to SO2 and oxides of nitrogen present in it.
Oxides of sulphur and nitrogen (SO2, NO, NO2 ) are the main air pollutants produced mainly by the combustion of fossil fuels for power generation.
In the atmosphere, SO2 and NO2 react with moisture forming respective acids (H2SO4 and HNO3 ) which then dissolving in water vapor in atmosphere fall onto the earth as acid rain. These acidic oxides may even undergo physical and chemical transformations producing toxic agents. About 60% - 70% of acids in the atmosphere are derived by the oxidation and hydrolysis of SO2 and H2S and rest 30% - 40% from various nitrogen compounds and other compounds.
Acid rain creates particles in the air that can cause respiratory problems.
It also causes building materials to decay more rapidly and paint more likely to peel.
Acid rain when mixed into the soil, it dissolves many of the essential nutrients the plant needs.
Acid rain raises the acidity of water of lake or pond which may destroy the aquatic life.