Effects of Man on the Environment PDF

Effects of Man on the Environmen t  Population Growth You should be able to: describe the factors that affect the growth of natural populations; and explain how man overcomes the constraints to human population growth. UNIT V III ENVIRONMENT CONTINU...

Effects of Man on the Environmen t  Population Growth You should be able to: describe the factors that affect the growth of natural populations; and explain how man overcomes the constraints to human population growth. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Growth of Natural Populations A population is a group of individuals of the same species living in the same place. Population growth rate is directly affected by two basic factors – birth rate and death rate. The rate at which babies are born is the birth rate, while the rate at which individuals die is the death rate. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth A typical population growth curve UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Growth phase Initially, the population growth rate is slow as there are only a few reproducing individuals that rarely meet and mate. The population growth increases rapidly (exponential growth) because of several factors. These factors include an abundant food supply, a lack of predation and disease. Amount of resources available > Amount required + rapid population growth + relatively low death rate = net population growth Maximum growth rate is at this stage. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Stability phase Eventually, the population growth slows down, due to the interaction of a few factors: Food supply. As the population increases, the food supply will start to run out. Predation. The low number of prey can only sustain a small number of predators. With more prey, predators have more food so their population also increases. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Stability phase Competition. Since members of a population share the same physical space and resources, they will compete with one another for food, territory and mates. Disease. Under overcrowded conditions, diseases spread easily, causing sickness and death. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth When the death rate is more or less equal to the birth rate, the population stabilises and growth stops. This population is known as the carrying capacity of the environment. This is the maximum population size that the resources of the environment can sustain for a period of time. The exponential growth of the population is kept in check by disease and predation. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Decline Phase Decline refers to a reduction in the number of individuals in a population. The possible factors causing decline are: ◦ a sudden change in the environment. ◦ the arrival of new predators or overpredation which is due to the increasing number of predators. ◦ Man’s actions UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Human population growth Humans are subjected to the same population growth constraints as other organisms, but they are able to overcome some of these constraints. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Space. Man has developed machines to clear forests and fill water bodies to create more land to support his needs. High-rise buildings can overcome land constraints to house schools, offices and apartments. Food. With the help of technological advances in agriculture, man is able to supply sufficient food to keep up with the rapid population growth. Disease. With better medical care and sanitation, the transmission of diseases has been greatly reduced. More treatments are also becoming available for diseases that previously had no cures. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Population Growth Although the quality of human life has improved drastically in the past century, there is still a great divide between the developed and less developed countries. The Earth’s resources, though plentiful, are limited  the exponential growth of humans cannot go on forever. There are certain factors that could stop future exponential increase in the world population. - Increased use and knowledge of contraceptive as countries develop. - As status of women increase, they no longer see their roles as only child bearers. - More women are marrying and having children at a later age. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN  Resources and their Use You should be able to: describe various resources and their limits; and understand the importance of recycling, and explain the difficulties encountered in recycling manufactured materials. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Resources and their Use Natural Resources Resources can be classified as being renewable or non- renewable. Renewable resources are those that can be reused or quickly replenished. Non-renewable resources are in limited supply, and cannot be replaced. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Resources and their Use UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Resources and their Use UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Resources and their Use Alternative sources of energy As Man become more aware that energy resources of the Earth are being used up at an alarming rate, they are turning to alternative sources for energy. These sources include solar, geothermal, tides and wind. The main advantage of these sources of energy is that they are renewable. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Resources and their Use Reduce, Reuse and Recycle Waste can either be biodegradable or not. To better manage waste, a strategy known as the 3Rs is developed. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Resources and their Use The Importance of Recycling Conserves land Reduces pollution Saves energy and resources UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Resources and their Use The Challenges of Recycling Recycling is an attitude and a habit to adopt as garbage has to be sorted before being discarded. It may be more costly to recycle products than make products from raw materials. It is usually more profitable for large companies. Recycling bins must be available and placed at strategic locations so people can see them. A certain amount of waste must be accumulated before it becomes worthwhile to be sent to the recycling factories. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN  Effects of Man’s Activities on the Environment You should be able to: understand the negative impact of human activity on the environment; discuss the implications of pollution on marine and wetland environments; and suggest means by which the environment could be conserved. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Pollution Pollution is the process in which harmful substances are added to the environment. The substances that damage the environment are called pollutants. The rapid increase in human populations also increases industrial activities and produces many toxic chemicals. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Air Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Air Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Air Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Ways of reducing air pollution Use catalytic converters in cars to increase fuel efficiency and reduce emission of carbon monoxide and nitrogen oxides Install pollution control devices such as filters on chimneys of power plants Reduce the burning of fossil fuels in factories Reduce the lead and sulphur dioxide content of fuel used in motor vehicles Burn cleaner fuel like natural gas to provide energy needs Use ozone-friendly products, such as spray cans that carry the “No CFCs” logo. Cut down on the use of cars and motor vehicles, and switch to using public transport or bicycles UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Water Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Water Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Water Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Water Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Water Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Water Pollution UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Sewage Treatment A typical sewage treatment process UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Deforestation Deforestation is the result of several activities, some of which are highlighted below: ◦ Urban development. Land has to be cleared for the construction of homes, industrial buildings, roads, etc. ◦ Commercial agriculture. With rising demand for food, more land has to be cleared for growing crops. ◦ Grazing pastures. Livestock such as cattle and sheep needs large expanses of grassland to move about and graze. ◦ Logging. Timber is a valuable raw material in construction, furniture-making, paper manufacture and firewood. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Effects of Deforestation ◦Soil erosion: no trees to hold the soil  easily eroded; fertile soil gets washed away and over time, land is destructed  dessertification ◦Flooding: eroded soil may be deposited in rivers, thus blocking the flow of water and cause flooding in low-lying areas ◦Species destruction: the loss of forests  loss of habitats for species to live in ◦Climate change: less trees to remove carbon dioxide from the air; loss of Earth’s “green lungs” Case Study: Simpson Bay Lagoon UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Conservation Conservation is the preservation of the Earth’s natural resources so that they are available for future generations. Conservation is important for two main reasons - to ensure that our demand for natural resources can continue to be met, and to maintain our quality of life. The goal of conservation efforts is to manage our natural resources in a sustainable manner. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Conservation measures Education ◦ E.g. Benefits of recycling, taking individual responsibility Legislation ◦ E.g. Ban the hunting and killing of endangered animals, set up nature reserves, ban logging, improve sewage treatment facilities. Conservation agriculture UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN Effects of Man’s Activities on the Environment Conservation agriculture Soil can be conserved if farmers adopt the following conservation measures: Carry out crop rotation which is planting different crops that use different nutrients from the soil, Implement fallow periods which give the soil ample time to recover its minerals, Use of cover crops to maintain soil cover, Use of organic fertilisers like manure and compost, so as to cut down on the use of chemical fertilisers, Plant trees and shrubs on farms(known as agroforestry) to prevent soil erosion. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN  Key Concepts Natural population growth normally has 3 phases – slow growth, rapid exponential growth and stability, where there is little or no growth. Population is prevented from expanding indefinitely by a limited food supply, predation, competition between individuals, and disease. Human population has been growing exponentially in the past two centuries, because of man’s ability to overcome the constraints of natural resources. Renewable resources include land, biotic resources and water. Non-renewable resources include fossil fuels and minerals. The large quantities of non-biodegradable waste which humans generate can be better managed by reducing, reusing and recycling waste materials. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN  Key Concepts Recycling is important as it helps to conserve land, reduce pollution and save energy. Air pollution is caused by the incomplete burning of fuel, the burning of fossil fuels and the manufacture of materials like metal ore. Water pollution is caused mainly by land activities, when toxic waste is discharged into seas and rivers. Water pollutants can enter our bodies through the plants and animals that we consume. Conservation is necessary to maintain the balance in an ecosystem and to preserve resources for the next generation. UNIT V III ENVIRONMENT CONTINUITY AND ANDVARIATION MAN