Environmental problems arise both due to natural processes and human activities. These problems adversely affect human and other forms of life.
Environmental problems may occur due to natural disasters or degradation caused by human activities. A disaster whether it is natural or man-made results in large scale damage to life and property. The effect of these disasters can be felt either locally or at the global level.
India being a country of many rivers and with tropical climate is one of the most flood-prone countries of the world. Floods are frequent because most of the rivers are full of water during monsoons. Flooding is caused by the inadequate capacity within the banks of the rivers to contain the high flow of water due to heavy rainfall. Areas having poor drainage get flooded by accumulation of water.
India has a long coastline, which is vulnerable to the tropical cyclones in the Bay of Bengal and the Arabian Sea. The Bay of Bengal region is frequently battered by storms and cyclones. Cyclones are intense low-pressure areas in the form of depressions or cyclone storms. Severe cyclones are associated with hurricane, winds, etc.
There are two cyclone seasons in India, the pre-monsoon season (April-May) and the post-monsoon season (October-December). The states of Odisha, Andhra Pradesh, Tamil Nadu and West Bengal are the most affected states due to cyclones.
Earthquake is a common phenomenon. It is the shaking, rolling or sudden shock of the earth’s surface. The intensity of earthquake is related to the amount of energy released when rocks give way to the forces within the earth. It is measured with the help of an instrument known as seismograph. The intensity of an earthquake is measured on the Richter scale.
From prehistoric times forests and fire have remained inseparable. Forest fires have become a major cause of concern because it threatens human habitats and deprives humans from accessing forest resources.
The word Tsunami is a Japanese word meaning ‘Harbor wave’. It involves the displacement of very large quantities of water due to earthquakes, landslides or volcanic eruptions. Tsunami occurs due to earthquakes under the ocean. Natural barriers such as shoreline tree cover can mitigate effects of Tsunami.
A landslide is the gravitational movement of a mass of rock, earth or debris down a slope. It occurs when a hilly slope becomes unstable. The natural reasons of a landslide are groundwater pressure acting to destabilize the slope, volcanic eruptions, earthquakes, erosion, etc. This is one of the natural environmental problems which is influenced by human activities such as deforestation, dynamite blasting of rocks, earth work, constructions, vibrations, etc. These activities need cutting down of trees whose roots hold the soil in place.
Landslides are a major hazard in most mountains and hilly regions as well as in steep river banks and coastlines. Landslides cause damage to lives, property and disruption in movement of traffic on highways (linking people living in hilly areas). They are a common feature in hilly areas.
A cloudburst is an extreme amount of precipitation, sometimes with hailstorms and thunderstorms. It occurs for few minutes and can create flood conditions which often results in landslides.
Large population size would require large scale resources such as water, food, space, energy, land, fuel, etc. which will certainly have a drastic effect on the environment at the local as well as global level. Although the growth in the human population leads to added stress on our resources indiscriminate and irresponsible use of our natural resources makes it even worse.
Large population means more land under cultivation for food production and water for irrigation, more fertilizers and pesticides in the environment. Forests are also cleared to create space for housing, roads, educational institutes, industries, etc. To meet the demand of food, housing and energy, environmental resources are being depleted at a fast pace. Environment has the potential to replenish most of its resources over a certain period of time. However, over-exploitation of resources and human activities has resulted in many environmental problems, such as:
Cutting of the natural forest cover is called deforestation. Forests are being cut for various purposes, such as for growing crops and grazing cattle, meeting the demand of wood and paper, etc.
Cutting down of forests may result in the following:
Any undesirable change in the environment due to human activity is pollution. Each activity, human or industrial, discharges some unwanted substances in the environment. The presence of unwanted substances in a concentration which can have an adverse effect on organisms and environment is called pollution.
Thus, an undesirable change in the physical, chemical and biological characteristics of the environment especially air, water and land that may adversely affect human population and the wild life and cultural assets (buildings and monuments, etc.) is called pollution.
Depending upon the area or the part of environment affected, pollution may be of the following types:
Anything which is unwanted or useless is termed as waste. The waste generated from various sources can be categorized into two types - Biodegradable waste and Non-biodegradable waste.
1. Biodegradable waste includes substances that can be degraded by microbes into harmless and non-toxic substances. Agricultural and animal wastes like leaves, twigs, hay, dung, etc. are biodegradable wastes.
2. Non-biodegradable waste cannot be easily degraded. Aluminum cans, plastics, glass, electronic waste, batteries, etc. are examples of non-biodegradable wastes.
Waste can also be classified as municipal waste, hazardous waste, biomedical waste, etc. Radioactive waste comes under the category of hazardous waste.
With the increasing population size, waste generated is becoming unmanageable. Open dumps and heaps of garbage is a common site. This unhygienic atmosphere leads to problems related to human health and environment because untreated, uncovered waste is a breeding ground for flies, rats, mosquitoes and other insects which spread various diseases. The rainwater run off from such sites contaminates nearby land and water.
If a waste material is processed by some means and converted to a product, we call the process recycling. It helps in efficient management of wastes and also reduces the load on natural resources. Recycling of plastics and paper, converting municipal waste into manure, and rice husk into wood particle board are some such examples. Use of cattle dung for the production of biogas is also good example of recycling of waste for the production of energy.
The ozone layer present in the earth’s atmosphere prevents the entry of sun’s harmful ultraviolet (UV) radiations reaching the Earth’s surface. Industrial use of chemicals called chlorofluorocarbons (CFCs) in refrigeration, air conditioning, cleaning solvents, fire extinguishers and aerosols (spray cans of perfumes, insecticides, medicines, etc.) damage the ozone layer.
Chlorine present in the CFCs on reacting with ozone (O3) layer splits the ozone molecule to form oxygen (O2). Thus, amount of ozone gets reduced and cannot prevent the entry of UV radiations. There has been a reduction by 30-40% in the thickness of the ozone umbrella or shield over the Arctic and Antarctic regions. This thinning of ozone layer is called ozone hole.
The depletion of ozone layer may lead to the following hazards:
Greenhouse is referred to as a chamber where plants are grown in a closed warm environment as compared to the outside temperature. This is normally practised in cold region of the hills. The solar radiations bringing heat (in the form of infra-red rays from the sun) are trapped inside the chamber. The atmosphere on earth can also act in a similar way.
Industrialization and urbanization has lead to deforestation and release of gases, such as CO2, CH4 and N2O into the atmosphere. These gases have converted the earth’s atmosphere into a Greenhouse. Heat contained in the solar radiations is allowed to come in, but the heat contained in it is not sent back due to increasing concentration of CO2 and other greenhouse gases. As a result, the earth’s average temperature is increasing each year leading to global warming.
Effects of global warming
Although the increase in global temperature in the last hundred years has been estimated to rise by only 1 degree, it has resulted in serious consequences, such as:
Pollutants like sulphur dioxide which is released while burning sulphur containing fuel and particulate matter like soot present in stagnant air masses, get modified in sunlight and form a sheet called photochemical smog.
Smog is a combination of fog, smoke and fumes released by mills and factories, homes and automobiles.
When sunlight falls on stagnant air under low humid conditions in the presence of pollutants such as SO2 soot, nitrogen oxide and hydrocarbons, photochemical smog is formed. (Photochemical: chemical reactions in the presence of light). Smog stays close to the ground and reduces visibility.
Photochemical smog is also called Pan smog due to the production of peroxyacetyl nitrate (PAN) and ozone which form from hydrocarbons and nitrogen oxides in the air in presence of solar radiation. PAN and Ozone are called photochemical oxidants. Both of these are toxic irritants to human lungs.
Smog formation is accompanied by temperature inversion or Thermal inversion. Temperature inversion causes smog to settle and remain near the ground till wind sweeps it away. Normally, warm air rises up into atmosphere. When a layer of cool air at the ground level is trapped there by an overlying layer of warm stagnant air, it is called temperature or thermal inversion.
Exposure to smog causes respiratory problems, bronchitis, sore throat, cold, headache and irritation to eye (red shot eyes). Smog also destroys crops and reduces crop yield.
Acid rain is caused when nitrogen oxides, SO2 and particulate matter in the atmosphere react with H2O to produce acids. Acid rain is harmful to the environment. It affects life in water and on land. The fish cannot survive in acidic water below pH 4.5. It can also damage trees in the forests.
In humans, it can cause asthma and premature deaths when food, water or air which is in contact with acid deposits is consumed. The soil characteristics are also greatly affected; this has an effect on the crops and agricultural productivity. The buildings, monuments are also damaged by acid rain. It also increases the corrosion rate of metals.