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MODULE - 1 Environmental Science Senior Secondary Course Environment through Ages Notes 3 DEGRADATION OF NATURAL ENVIRONMENT When humans evolved more than two millions years ago, the natural resources were over abundant as compared to human needs. As human population increased, more and more food and resources for shelter were required and these were drawn at an increasing rate from the environment. Even today, natural resources are being exploited by humans to meet their needs. In this lesson you shall learn how human activities degrade and deplete the natural resources of the environment. OBJECTIVES After completing this lesson, you will be able to: · recall the concept of environmental degradation and factors that cause it; · explain how exploitation of natural resources leads to environmental degradation; · explain the relationship between population growth and environmental degradation; · explain the relationship between urbanization and deterioration in environment; · explain the causes and effects of deforestation; · draw a relationship between excessive mining and environmental degradation; · explain the meaning of fossil fuels and the impact of their use on the environment; · discuss how modernization of agriculture has adversely affected the environment; · discuss the impact of industrialization on abiotic (air, water and soil) and biotic resources (plants and animals) of the environment; · list local, regional and global backlashes caused by environmental degradation; · describe the impact of environmental degradation on life. 32 Degradation of Natural Environment MODULE - 1 Environment through Ages 3.1 CONCEPT OF ENVIRONMENTAL DEGRADATION Increasing use of natural resources by rapidly increasing human population has resulted in overexploitation of natural resources. The consequences of such exploitation are clearly seen in soil erosion, loss of biodiversity and pollution of land, air and water bodies. The Notes degradation of the environment from overexploitation has reached a level which is threatening human well-being and survival. 3.2 RECKLESS EXPLOITATION OF NATURAL RESOURCES LEADS TO ENVIRONMENTAL DEGRADATION In nature, there exists an ecological balance. The activities of various organisms are balanced. The interaction between abiotic and biotic components are so fine tuned that there exists an equilibrium in nature. As years passed by, human activities interfered with this equilibrium. Uncontrolled human activities caused damage to the environment. Some of the human activities that have led to environmental degradation are mentioned below- 1. Forests are natural resources but they have been cut down for use by humans for converting them into the cultivable fields, for building houses and for taking away logs for making shelters and furniture or fuel. The rate at which trees are cut far exceeds the rate at which trees grow, so forests are getting denuded. 2. Trees lose lot of water through transpiration. This helps in forming rain clouds. Cutting of trees and clearing of forest reduced rainfall in the area. Also removal of plants and trees leads to soil erosion. 3. Forests are natural habitats of wild life. Extinction of wild life species is on the rise because their natural habitats are being destroyed due to deforestation. 4. Non-renewable energy resources such as coal, natural gas and petroleum are being used up speedily, leading to their depletion. These are examples show the loss of natural resources due to the overuse by humans. On the other hand, 1. Excessive burning of coal, wood, kerosene, petrol etc. release toxic gases such as SO (sulphur dioxide), NOx (oxide of nitrogen),CO(carbon monoxide) and 2 hydrocarbons in the air. These gases are also emitted by industries, power plants, automobiles and aircrafts. The toxic gases pollute air which adversely effects human health and plants. 2. Acid water from mines, toxic waste of industries, chemical fertilizers and pesticides from agricultural fields have polluted rivers and other water bodies. 33 MODULE - 1 Environmental Science Senior Secondary Course Environment through Ages 3. The problem of soil pollution is increasing day by day in villages, cities and industrial areas due to faulty disposal of solid and liquid wastes generated from households and industries. Thus humans have spoilt the environment by (i) depleting natural resources to a critical Notes level and (ii) causing pollution to natural water bodies and land areas. 3.3 IMPACT OF POPULATION GROWTH ON ENVIRONMENT The enormous increase in human population is making the future of humans insecure. It is estimated that 5 million people lived in the world at the time when agriculture begin about 12000 years ago. The population of our country alone is now well over one billion. 3.3.1 Factors leading to rise in population Many factors have contributed to the enormous rise in human population. These are listed below: 1. Improved agricultural practices have helped in increasing food production, hence food became available. 2. Progress in medicine prevented deaths due to injury and epidemic diseases. 3. Average longevity of humans has increased since heart, lung and kidney disorders as well as other diseases can now be diagnosed and treated through modern medical technology. 3.3.2 Impact of population growth on environment With growing population, requirement for space, shelter, and commodities have exerted enormous pressure on the environment. To provide for these, land use has change dramatically. It has already been seen that forests have been cleared for cultivation of grain and fruit crops. 1. Clearing land for cultivation to grow more food Forests and natural grasslands have been converted to farmlands. Wetlands have been drained and arid lands have been irrigated. These changes have been made to grow more food and more raw materials. But in doing so, the natural resources have been depleted and the landscapes have undergone drastic changes. For example, forests have been cleaned over large for cultivation of agriculture crops. Many mangrove forests known to reduce erosion and stabilize shorelines have been cleared use for growing food crops to meet the needs of the growing population. 2. Water scarcity Water received as rainfall, flows into rivers, lakes and other water bodies. Some of it seeps into the ground and reaches the ground water. At certain depth of the soil, all the pore spaces between soil particles are saturated with water. This depth is called Water 34 Degradation of Natural Environment MODULE - 1 Environment through Table. The water table may remain stable if the drawn from the ground water is replenished Ages by the seepage of the rain water. But if water withdrawal exceeds beyond the rate of replenishment of the ground water table keep on receding and resulting in drying out of wells. In many areas excessive withdrawl has depleted ground water resources causing acute water scarcity. Notes 3. Need for human settlements Apart from excessive land use changes for growing food, large population means greater requirement for shelter. To make houses for so many, stones and other building materials have to be quarried more rocks have to be blown off and more water to be used. 4. Need for transport Elaborate network of transport is required to fulfill the growing need of teeming millions. Various modes of transports have been developed which consume growing quantities of fossil fuels such as coal, gas and petroleum, polluting the atmosphere. 5. Need for various commodities Articles of everyday use such as plastic vessels, mugs, buckets etc., agricultural implements, machinery, chemicals, cosmetics etc are manufactured in factories. The raw materials and fossil fuels and water needed to run industries for manufacturing these products lead to their depletion. Rapid industrialization has also led to pollution from dumping of industrial effluents into rivers and other water bodies. Rapid industrialization has caused much damage to the environment. Mining activities have depleted stock of mineral resources particularly fossil fuels. Present day industrial civilization is becoming a burden on nature and it is time for us to learn to live in harmony with nature. 6. Slum development Over populated areas result in congested roads and slum formation which lack basic amenities like drinking water, drainage, waste disposal, lack of hygienic conditions and filthy environment create potential conditions for public health problems including spread of epidemic diseases. Discharge of untreated effluents and throwing of waste into water bodies have polluted most of the lakes and rivers. 7. Pollution resulting from overpopulation Holy rivers Ganga, Yamuna and other are suffering from pollution due to discharge of effluents from industries, human settlements, bathing, washing of clothes and throwing of garbage into the river. INTEXT QUESTIONS 3.1 1. State any two types of environmental degradation caused by humans. ______________________________________________________________ 35
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