Presentation on theme: "University of Khartoum Institute of Environmental Sciences Dip/ M.Sc in Enviromental Sciences Fundamentals of Environmental Science By: Dr. Zeinab Osman."— Presentation transcript:
University of Khartoum Institute of Environmental Sciences Dip/ M.Sc in Enviromental Sciences Fundamentals of Environmental Science By: Dr. Zeinab Osman Saeed
Lecture nu 7
Man-Environment interaction Earliest men lived as hunters. They depended on a small number of animals and wild vegetation on earth. They were able to fit into food web, carbon cycle and nitrogen cycle of their ecosystem. Once agricultural techniques had been improved, the earth could support a larger population.
Agriculture The development of agriculture has been central to the advancement of human civilization. Its practice forced humans to form settled communities with divisions of labor and practices different from those of hunting and gathering. Two serious environmental issues regarding agriculture are the greenhouse effect and pollution from fertilizers and pesticides.
Monoculture When a large piece of land is used to grow crops of the same species for a long time. Effects: 1. Deforestation 2. soil erosion 3. Flooding mud slides 4. Siltation and sedimentation 5. Habitat destruction 6. Species extinction
Environmental impacts of agriculture Greenhouse effect: Increasing CO2 emissions. Biofuels Methane from rice agriculture.
Fertilizers Nitrogen and phosphorous fertilizers have increased the soil nutrient levels Fertilizers cause irreparable damage to the environment. The fixation of nitrogen for agriculture has drastically increased the amount of nitrogen present as the nutrative ions ammonium and nitrate.
Phosphorus cycle The phosphorous used by plants is predominantly in the form of phosphate salts. Phosphate salts are absorbed through the roots of plants and used to make organic compounds. As animals eat these plants, P is also consumed and passed up the food chain. The decomposition of these animals or the excretion of organic phosphate returns phosphorous into the soil or water thereby completing the cycle.
Eutrophication The natural process by which lakes, streams and some estuaries age. Activities such as land clearing, application of fertilizers, agricultural runoff and release of human waste have resulted in the mobilization of nutrients such as nitrogen and phosphorous into aquatic systems, increasing the growth of unwanted algae and aquatic weeds. As these die, they reduce the oxygen supply available to other organisms. The debris accumulated from dead organisms eventually fills bodies of water.
Groundwater contamination Fertilizer contamination of water can be a human health hazard. Nitrate(NO3-) is reduced in the intestines to nitrite (NO2-). Nitrite in turn oxidizes iron ions contained in hemoglobin from Fe2+ to Fe3+. This form of iron is not effective in binding oxygen which results in blue baby syndrome which causes respiratory failure in infants.
Desertification Desertification is the degradation of land in arid and dry sub-humid areas, resulting primarily from natural activities and influenced by climatic variations. It is also a failure of the ecological succession process. A major impact of desertification is biodiversity loss and loss of productive capacity.
Desertification This degradation of formerly productive land is a complex process. It involves multiple causes, and it proceeds at varying rates in different climates. Desertification may intensify a general climatic trend toward greater aridity, or it may initiate a change in local climate.
Desertification The Sahelian drought that began in 1968 was responsible for the deaths of between 100,000 and 250,000 people, the disruption of millions of lives, and the collapse of the agricultural bases of five countries.
Causes Desertification is induced by several factors, primarily anthropogenic causes. The primary reasons for desertification are: overgrazing over-cultivation increased fire frequency water impoundment
Causes deforestation overdrafting of groundwater increased soil salinity global climate change
Industrialisation Industrialisation is the process of social and economic change whereby a human group is transformed from a pre-industrial society into an industrial one. It is a part of a wider modernization process, where social change and economic development are closely related with technological innovation, particularly with the development of large- scale energy and it metallurgy production
Industrialization through innovation in manufacturing processes first started with the Industrial Revolution in the north-west and midlands of England in the eighteenth century. It spread to Europe and North America in the nineteenth century, and to the rest of the world in the twentieth.
The mechanization of production spread to the countries surrounding England in western and northern Europe and to British settler colonies, making those areas the wealthiest and shaping what is now know as the Western world.
Effect on environment Industrialization has spawned its own health problems. Modern stressors include noise, air, water pollution, poor nutrition, dangerous machinery, impersonal work, isolation, poverty, homelessness, and substance abuse. Health problems in industrial nations are as much caused by economic, social, political, and cultural factors as by pathogens. Industrialization has become a major medical issue world wide.
Factories and urbanization Industrialization led to the creation of the factory. Arguably the first was John Lombe's water-powered silk mill at Derby, operational by The factory system was largely responsible for the rise of the modern city, as large numbers of workers migrated into the cities in search of employment in the factories. Nowhere was this better illustrated than the mills and associated industries of Manchester, the world's first industrial city.
Urbanization is the physical growth of rural or natural land into urban areas as a result of population immigration to an existing urban area. Effects include change in density and administration services. While the exact definition and population size of urbanized areas varies among different countries, urbanization is attributed to growth of cities.
Urbanization It is also defined by the United Nations as movement of people from rural to urban areas with population growth equating to urban migration. The UN projects half the world population will live in urban areas at the end of Urbanization refers to a process in which an increasing proportion of an entire population lives in cities and the suburbs of cities.
Urbanization Historically, it has been closely connected with industrialization. When more and more inanimate sources of energy were used to enhance human productivity (industrialization), surpluses increased in both agriculture and industry. Larger and larger proportions of a population could live in cities. Economic forces were such that cities became the ideal places to locate factories and their workers.
Urbanization A "city" refers to a place of relatively dense settlement -- dense enough so that city residents can not grow their own food. A city population, therefore, is always dependent upon its "hinterlands" to provide it with food.
The global proportion of urban population The UN World Urbanization Prospects report showed that, the global proportion of urban population rose dramatically from 13% (220 million) in 1900, to 29% (732 million) in 1950, to 49% (3.2 billion) in The same report projected that the figure is likely to rise to 60% (4.9 billion) by 2030.
In regard to future trends, it is estimated 93% of urban growth will occur in Asia and Africa, and to a lesser extent in Latin America and the Caribbean. By 2050 over 6 billion people, two thirds of humanity, will be living in towns and cities.
Causes Urbanization occurs naturally from individual and corporate efforts to reduce time and expense in commuting and transportation while improving opportunities for jobs, education, housing, and transportation. People move into cities to seek economic opportunities. In rural areas, often on small family farms, it is difficult to improve one's standard of living beyond basic needs.
Causes Cities, in contrast, are known to be places where money, services and wealth are centralized. Businesses, which generate jobs and capital, are usually located in urban areas. Whether the source is trade or tourism, it is also through the cities that foreign money flows into a country. There are better basic services as well as other specialist services that aren't found in rural areas. There are more job opportunities and a greater variety of jobs.
Causes Health is another major factor. People, especially the elderly are often forced to move to cities where there are doctors and hospitals that can cater for their health needs. Other factors include a greater variety of entertainment (restaurants, movie theaters, theme parks, etc) and a better quality of education, namely universities
Environmental effects The urban heat island has become a growing concern. This effect causes the city to become 2 to 10 o F (1 to 6 o C) warmer than surrounding landscapes. Impacts also include reducing soil moisture and intensification of carbon dioxide emissions Pollution. Waste.