Каталог :: Экология

Реферат: Urbanization


Urbanization is one of the most controversial problems of modern society. Although it is an essential process of social and economical development of humans, it also the source of the problems that people never faced before. Anyone familiar with the world development trends knows that nearly half of the world’s population lives in urban areas and the number are expected to grow by 2% every year. Because of greater engagements in non-farm activities and driven by financial or educational needs people shifts to cities, causing the rapid growth of urban areas. Cities play not only the role of employment, shelter and service but also play the role of center of culture, education and portal to the rest of the world. Although, cities and their ecology have a thousand years of evolving history, the term “urbanization and ecology” surprisingly only appeared very recently. For example, term ”Urbanization” was born only in the middle of 19th century, when with the expansion of industry people started to move from rural to urban areas causing vast pressure on the capacity of cities. Air pollution, acid rain, and imbalance of ecology made the term “ecology of urbanization” more and more relevant in 20th century and made the public pay more attention to this issue. It is kind of scary to realize that this kind of important issue is only a little bit older than me. Modern urbanization process has tons of problems, starting with insufficient housing and ending with global ecology impact. In this paper, I tried to cover a little piece of the ecology problems that urban areas are facing these days: air, water, waste and ecological footprint. The paper is designed to cover the basic ideas of ecological impact and how significant it can be if we don’t realize it soon.

Urbanization and ecology

Everybody knows the obvious correlation between urbanization and economic development; some Asian countries rapidly developed during 70’s and 80’s, the time when the large movement of population from rural to urban was recorded. According to UN report, worldwide, cities produce on average 60 percent of a country’s GNP. Bangkok, for example, produces 40 percent of Thailand’s output, whereas only 12 percent of its population lives in this city. Cities are undoubtedly the basis for any functioning economy and it will keep remaining important in the future. As mentioned in the introduction, cities are the centers of culture and economic prosper, but the mismanagement and poor economical development can turn the cities into centers of unemployment, poverty and pollution. As the city grows it needs more lumber, more steel, more labor and more land. They absorb the agricultural land for urban use, the forest for construction and all sorts of raw materials for growth. A city the size of San Francisco has more copper and aluminum than a medium size mine; more lumber than some countries have in their forest. Cities behave like a giant growing monster, eating and swallow everything round it, while at the same time spoiling and wasting surrounding areas. High concentration of cars and industries causes the air and water pollution, high demand produces extra wastes and high density requires more land. In many cases cities are the only cause of the instability of the sensitive ecosystem of the region. Until recent time the false attitude was popular that only cities of developed countries has an ecology problem. Breaking point was in 1972 when UN’s Stockholm conference on ecology declared that ecology of urbanization is one of the difficult problem almost in all countries, no matter where. One of the reasons of environmental pollution in the developing countries is weak legislation enforcement. Cheap production cost, weak legislation enforcement and corrupted officials are the signs of easy money in developing countries. As a result many corporations from developed countries moved their production of hazardous and dangerous products in to third world. Instead of paying millions of dollars for cleaning and security equipments, they are enjoying a quite safe and cheap environment in hosting countries and harming environment without even bothering about it. Most of these productions usually located within the urban zones. For example, research done in Nicaragua in 1980, found the source of mercury poisoning among the population in capital city. Uncontrolled down throw of mercury by American corporation leaded to enormous poising of environment. In fact the content of mercury in the city water was 12 times higher than it was allowed in the US.

Air and water of condition of urbanization

Air pollution Under the term “ecological disaster” we understand that one constant system changes to another unstable system. For example, increase in average temperature on Earth leads to melting of polar ice, which can have an unpredictable consequence; or spread of the ozone hole can bring all sorts of diseases or death to a many life forms. One or all of these disasters would occur as the product of our activity if the countries won’t pay enough attention to greenhouse effect of emission. Urban air pollution is one of the most important environmental problems. High concentration of transportation, industry and people turns the city into perfect polluter of the air. According the statistical data, the main sources of air pollution are vehicle exhaust, industrial emissions, and domestic use of wood, coal and refuse for heating and cooking. But in the city the lion share of air pollution belongs to transportation. Vehicles contribute about 14% of total global air pollution but in big cities it can contribute up to 80% of the city’s emission. There are about 600 million units of vehicles in the world, and every type produces about 3-4 kg of carbon dioxide, more than our nature can absorb. In most European and North American cities, the concentrations of SO2 and Suspended Particulate Matter (SPM includes dust, fumes, mists and smoke — SO2 and troposphere ozone) have decreased substantially in recent years. However, in the US every second person has a car, about 170 million cars with the population of 280 million people; high concentration of industry and transportation turned the US into one of the biggest air polluters in the world, even though the number is decreasing. The US account for 26% of the total air pollution in the world. The problem is not only in developed countries. In many developing countries, rapid urbanization has resulted in increasing air pollution in many cities. WHO air quality guidelines are often not met and, in mega cities such as Beijing, Calcutta, Mexico City and Rio de Janeiro, high levels of Suspended Particulate Matter (SPM) prevail. The result of air and water pollution is chronic and infectious respiratory disease; water borne diseases; increased mortality rates, particularly among children; and premature deaths – the highest rate being among the poor. In Cairo, the leading polluted city, there are about 10.6 million people with respiratory disorder (SEI 1999). Air pollution is not only the cause of lung disease, but also has become the cause of heard attacks, birth defects and cancer. In developing countries, transportation is not the main source of air pollution. For example China and India together have about 600 million bicycles and much, much fewer cars. If in the US every second person has a car, in China only every 79th person has a car, so the sources of pollution are different. People move from rural to urban areas to find better job and a better life, so many cities in China have a housing problem. Because the city can’t offer decent housing, people live in small self-built shelters and usually heating and cooking is done by burning a very low quality coal, because it is the only cheap source of energy. Beijing is one of the air polluted cities in the world and because of air pollution they have a desert problem. All green plants around the city are dead and any efforts to plant new trees and grass have had a miserable result. The geographical location plays not last role in the determination of air pollution of cities. For example, some cities in South America, which are located in high mountains have natural problem with free flow of air movement that removes polluted air. Besides, the low oxygen concentration in high mountain areas causes the partial burn of the fuel, which simply worsens the situation. For example Mexico city, the second largest city in the world, has a big problem with smog – dry, smoky fogs, which consist of carbon dioxide and nitrogen dioxide. Sometimes the smog stays for few days in the city without any movement, causing enormous harm to the health of citizens of Mexico city. Water pollution Water pollution problems vary in severity around the world, depending on population densities, the types and amounts of industrial and agricultural development, and the number and efficiency of waste treatment systems that are used. For a millennia, people have used water as a convenient sink into which to dump wastes. The pollution comes from many sources, including untreated sewage, chemical discharges, petroleum leaks and spills, and agricultural chemicals that are washed off or seep downward from farm fields. In one area after another, the amounts and types of waste discharged have outstripped nature's ability to break them down into less harmful elements. Pollution spoils large quantities of water which then cannot be used, or at best can be used for restricted purposes only. A growing number of regions face increasing water stresses because more people are both polluting and demanding more water for all uses from a renewable but finite resource. They are thus suffering from scarcities caused by failure to adapt to the amount of water that is regularly made available by rain and snowfall. Water demands are so high that a number of large rivers decrease in volume as they flow downstream, with the result that downstream users face shortages, and ecosystems suffer, both in the rivers and in adjacent coastal areas. Many underground water resources, known as groundwater, are being drained faster than nature can replenish them. Intensive and misuse of underground water leads to drainage of water recourses around the city, deserting the big areas beyond the cities boundaries. In some cases, groundwater depletion results in the land above aquifers sinking. Land subsidence caused by high water withdrawals has been recorded in many countries, including Mexico, the United States, Japan, China and Thailand, with the land sinking from 1 to 10 meters. South and Southeast Asia are facing severe water pollution problems. Rivers such as the Yellow (China), Ganges (India), and Amu and Syr Darya (Central Asia) top the list of the world’s most polluted rivers. In cities in the developing countries of the region, most water bodies are now heavily polluted with domestic sewage, industrial effluents, chemicals and solid wastes. Most rivers in Nepal’s urban areas have been polluted and their waters are now unfit for human use, while drinking water in Katmandu is contaminated with coliform bacteria, iron, ammonia and other contaminants. There are estimates that in developing countries, which often lack the resources to build and maintain sewage treatment a system, 90 per cent of waste water is discharged without treatment. A UN study found that in Latin America, virtually all domestic sewage and industrial waste is discharged untreated into the nearest streams. In most areas, domestic sewage volumes are far higher than those of industrial discharges. There were similar findings from West Africa, where there were signs of shallow aquifers being contaminated by the seepage of human wastes.

Waste management

Some estimates show that New York wastes round 24’000 ton material everyday. It contains metal, glass, plastics, paper, food and etc. It also includes dangerous substances like mercury from battery, phosphate from bulbs and other different type of toxic waste from paintings, detergents, home cleaners and etc. The sad fact is that wealthy city tends to use more energy and produce more waste than similar developing country’s cities. Developing countries trash about 2-3 times less waste than developed country. To satisfy an average costumer, for example, a company uses more packaging than it needed or more advertisements than it requires, which in other words mean more waste. Among the nations, the US produces the highest waste per person – 520 kg waste per person a year; in comparison Norway, Spain, Nederland – 200-300 kg, African cities – much less. Depending on the country and its economic stand, there are different approaches to the waste management. Rich and developed countries or countries with scarce land supply use high tech processes to handle the waste. But on opposite side, poor and developing countries are still using the simple methods of waste discharge. Open Waste Area and Land Filling. Until recent time, 90% of waste in US is used to bury. Open dumping takes more space and more energy to handle it and usually becomes the shelter of different type of leaving creatures; rats, mosquitoes, bags - the potential carriers of diseases. The process of rotting of organic waste spreads strong smell to surrounding area, and the wind disseminates the loose trashes. In developed countries there are almost no open dumping areas nowadays (except for solid waste), but in third world it is the only way of handling the waste; cheaper and more convenient. The heartbreaking fact is that those open waste areas, in third world, become shelter and the only source of income for many poor people. Ecological impact of open dumping is wide and significant. The content of waste can be various, starting from usual organic waste and ending with heavy chemical products, which can be dissolved by rain or snow water. It leaks to underground water and can spread many miles away from the original source. In the past, people used open dumping because most of the waste used to be absorbed by the nature; wind, water, ground and sun dissolve the waste. But with the advance of the technology many items just simply don’t dissolve easily. For example, paper takes two to ten years to completely disappear, cans – more than 90 years, filter from cigars – more than 100 years, plastic bags – 200 years, plastic – 500 years, glass – 1000 years. With the danger of heavy pollution many countries changed open dumping to land filling. Waste problem was solved for a decade, no more headaches for government. But with more pollution of underground water and threat to health, people realized the hidden danger. Nowadays, land filling is a very sophisticated process; just simple burying turned into high technological storage areas. In the US 20 years ago, simply bury of waste cost $2 per kg, now cost round $100 per kg; burying one liter of organic dissolvent costs more than its production and it has an increasing tendency. With production of 160 million tons of waste every year, the US has not only the problem of the expenditure, but also the rapid fill ups of land filling areas. Waste-to-energy High-density areas like Europe don’t have much land to landfill so they preferred to burn the waste instead of burying. The first systematic chain furnace was tested in England in 1874. Burning decreases the size of waste about 70 - 90 percent and ashes easily turn into construction materials. This method was adapted on both sides of Atlantic Ocean; in Europe early, in America little bit later. In the developed world waste burning is used for production of electrical and steam energy, construction supplies and crude iron. For example, the leading US’s waste company the “Waste Management Co.” produces about 623 megawatts of energy every year, which is equivalent of supplying 550,000 homes with energy. According company’s report:” . “WM” has processed over 100 million tons of municipal solid waste into energy since 1975, saving more than 150 million barrels of oil while producing 50 billion kilowatt hours of electricity.” Burning the waste for a production of energy also has its downside. Waste itself is a very difficult burning material. It requires special expensive process to be burnt and not everywhere it repaid the expenditure. For example Moscow had a problem when they tried to establish the new plant. Mayor of Moscow agreed to put in budget to purchase of furnace from western countries but refused to buy the cleaning equipment, because the emission cleaning equipment cost almost the same price as the plant itself. Without the cleaning equipment amount of carbon dioxide it excretes into the air is enormous. Moscow has an air pollution problem without the waste burning plant so the project was canceled. Most of the third world burning plants work because of subsidies of international organizations. But in many, many developing countries this technology just simply didn’t find the usage. It is much cheaper just burning the waste on open area than trying to turn into energy. Recycling So far the most perspective management of waste known to people is recycling. It doesn’t require much government subsidy, doesn’t pollute environment and it is economically efficient. Sweden is one of the highest recyclers of thee aluminum cans, 8 of 10 cans is recycled. Production of cans from recycled material cost only 40% of its original cost. From recycled material produced construction material, furniture, paper towels and all sorts of plastic items. Besides of its economical meaning it has great positive impact on environment; there are less need to cut the tree or explore the new mine. In the US, nowadays, about 20 % of the waste is recycled.

The ecological footprint of Urbanization

Everybody, from a single individual to a whole city or country, has an impact on the Earth, because they consume the products and services of nature. Their ecological impact corresponds to the amount of nature they occupy to keep us going. The definition of footprint is: "The ecological footprint is the corresponding area of productive land and aquatic ecosystems required to produce the resources used, and to assimilate the wastes produced, by a defined population at a specified material standard of living, wherever on Earth that land may be located." If the footprint exceeds the available biologically productive area of the country, it runs an ecological deficit, which in other words the country’s area alone cannot provide sufficient ecological services to satisfy its population’s current patterns of consumption. London - with 12% of Britain's population covering 170,000 hectares - comes to some 21 million hectares or 125 times the surface area of the city itself, equivalent to the entire productive land in the UK. The city of Vancouver, Canada, indicates that city appropriates the productive output of an land area nearly 174 times larger that its political area to support its present consumer lifestyle. Other researchers found that the aggregate consumption of wood, paper, fiber and food by the inhabitants of 29 cities in the Baltic Sea drainage basin appropriates an area 200 times larger than the cities themselves. Footprint of the Netherlands appropriates between 100,000 sq. kilometers and 140,000 square kilometers of agricultural land, mostly in the third world, for food production alone, it is almost 3-4 times larger than the actual land. Scientists have calculated that a typical North American city with a population of 650’000 people would require 30’000 km sq of land, an area roughly the size of Vancouver Island in Canada, to meet its domestic needs without including the environmental demand of industry and I believe that the ecological footprint would be enormous. A similar sized city in India would require only 2’900 sq km. Despite small size, few natural resources, and relatively large populations, both Holland and Japan enjoy high material standards and positive current accounts and trade balances as measured in monetary terms. However, our analysis of physical flows shows that these and most other so-called "advanced" economies are running massive, unaccounted ecological deficits with the rest of the planet. The different data of different researchers emphasizes that most developed countries are over-populated in ecological terms - they could not maintain themselves at current material standards if forced by changing circumstances to live on their remaining endowments of domestic natural capital.


Researchers like to characterize humanity's impact on the environment through three factors: population, consumption and technology. Someone said:” The pollution problem is a consequence of over population”. The humanity almost doubled within the century and soon we are going to double again, no wonder that we are facing the pollution problems. There are not much can be done about population growth, because we all have the freedom of living and breading. Everyone would like to leave behind the posterity. So maybe we must concentrate on cutting back on consumption. I’m not saying that we must give up all the comfort that our modern world offers to us but at least we must try to use fewer, like saving the energy by turning off the unused electrical equipment or thinking twice before buying the co-called transportation “SUV” which travels only eleven miles on one gallon of gas, which is insane. And finally, we must try to develop our technology on high level and share with others. More efficient and safe technology is our last hope on better environment. Imagine, what will happen if all transportation will work on battery or by the wind. It is so exciting to think about all the benefits that humanity can derive from it. Urbanization will continue to play a leading role in the economy, environment and people’s life. The challenge is just to learn how to live with urbanization while using its benefits and guiding undesirable and negative impacts in manageable direction.