Hydrocarbon Pollution from Vehicle Exhaust
Vehicle exhaust contains a number of airborne pollutants that affect the health of animals and plants and the chemical nature of the atmosphere. Carbon dioxide and hydrocarbon emissions, two of the main ingredients of vehicle exhaust fumes, add to global warming and are produced as a by-product of the combustion of petroleum-based fuels.
Acid Rain
Chemicals such as sulphur dioxide and nitrous oxides interact with sunlight, moisture, and oxidants to produce sulphuric and nitric acids. These are carried in the atmosphere and come to Earth in rainfall and snowfall, commonly referred to as acid rain.
Acid rain is a localized problem. The acidity of some rain that falls in northern North America and Europe is equivalent to that of vinegar. Acid rain corrodes metals, weathers stone buildings and monuments, injures and kills vegetation, and acidifies lakes, streams, and soils, especially in north-eastern North America and northern Europe. In these regions the acid level in the lakes has killed some fish populations. It is also now a problem in the southeastern and western United States. Acid rain can also slow forest growth, and this has been a major problem. It is associated with forest decline at higher regions in both North America and Europe.
Marshy Spruce Forest Damaged by Acid Rain
Forests, lakes, ponds, and other land and water habitats in the world are being severely damaged by the effects of acid rain. Acid rain is caused by the sulphur dioxide and nitrogen compounds with water in the atmosphere to produce rain with a very low pH. Normally, rainwater has a pH of 6.5, making it very slightly acidic. However, in acid rain, the pH of water may drop to as low as 2.0 or 3.0, similar to the acidity of vinegar. Acid rain burns the leaves of plants, poisons lakewater, which kills most if not all of the fish, insect and plant life.
Toxic Substances
The manufacturing, processing, distribution, use, and disposal of toxic substances (chemical and mixtures of chemicals) present an unreasonable risk to human health and the environment. Most of these toxic substances are synthetic chemicals that enter the environment and stay there for long periods of time. Large amounts of toxic substances occur in chemical dump sites. If they find their way into soil and water, the chemicals can poison water supplies, air, crops, and domestic animals, and have been associated with human birth defects, miscarriages, and organ diseases. Despite known dangers, the problem is not diminishing. In a recent 15-year period, more than 70,000 new synthetic chemicals were manufactured, and new ones are being created at the rate of 500 to 1,000 each year.
The pollution of rivers and streams with chemicals has become one of the most worrying problems of the 20th century. Chemical pollution entering rivers and streams comes from two major sources: those which can be easily identified, such as factories, refineries or outfall pipes and those from sources that cannot be precisely identified; such as runoff from agricultural or mining sites or seepage from septic tanks or sewage drain fields. It is thought that each year 10 million people worldwide die from drinking contaminated water.
Loss of Wild Lands
Increasing numbers of human beings are intruding on remaining wild lands—even in those remote places thought relatively safe from human invasion. Continual demands for energy are forcing the development of Arctic regions for oil and gas and threatening there’s plant and wildlife. Tropical forests, especially in southeastern Asia and the Amazon River Basin, are being destroyed at an alarming rate for timber, the land is then used for crops, grazing lands, pine plantations, and settlements. It was estimated at one point in the 1980s that such forest lands were being cleared or converted at the rate of 20 hectares a minute; another estimate put the rate at more than 200,000 sq km a year. In 1993 satellite data provided a rate of about 15,000 sq km a year in the Amazon Basin area alone. This tropical deforestation has already resulted in the extinction of as many as 750,000 species, and is likely to wipeout millions if allowed to continue unchecked. This would mean the loss of many products: food, fibres, medical drugs, dyes, gums, and resins. As well as this, the increase in croplands and grazing areas for domestic livestock in Africa, and illegal trade in endangered species and wildlife products, could mean the end of Africa’s large mammals.
Slash and Burn Deforestation
The deforestation technique of slash and burn, utilized extensively to clear large areas of forest for agricultural and other purposes, causes an enormous amount of environmental damage. The large amount of carbon dioxide given off into the atmosphere during burning adds to the greenhouse effect. The removal of all trees and groundcover destroys animal habitats and greatly accelerates erosion, adding to the sediment loads of rivers and making seasonal flooding much more severe.
Soil Erosion
Soil erosion is increasing on every continent but Antarctica and is damaging one fifth to one third of the cropland in the world, threatening the world’s food supply. For example, erosion is affecting the productivity of 35 per cent of all cropland in the United States. In the developing world, increasing needs for food and firewood have resulted in deforestation and the farming of steep slopes, causing severe erosion. Adding to the problem is the loss of prime cropland to industry, dams, urban sprawl, and highways. The amount of topsoil lost each year is at least 25 million tonnes, which is enough, to grow 9 million tonnes of wheat. About half of all erosion is in the United States, the former Soviet Union, India, and China. Soil erosion and the loss of cropland and forests also reduce the moisture-holding ability of soils and add sediments to streams, lakes, and reservoirs.
Gully Formation Due to Soil Erosion
Gully formation, a severe form of soil erosion, is a natural geological process that can be greatly increased by human activities such as deforestation, overgrazing of cattle, and poor agricultural practices. Erosion attacks the moisture-bearing ability of soils and adds soil deposits to waterways. This destruction is continuing at an increased rate on every continent, as overpopulation and industrialization increase demands on the remaining soil.
The Earth Summit
In June 1992 the United Nations Conference on Environment and Development, known as the Earth Summit, gathered for 12 days on the outskirts of Rio de Janeiro, Brazil. The Earth Summit developed a broad agenda for environmental, economic, and political change. The purpose of the conference was to identify long-term environmental reforms and to start putting those reforms into action. Meetings were held to discuss and adopt documents on the environment. The major topics covered included climate change, biodiversity, and forest protection. The Earth Summit was an historic event of great importance. Not only did it make the environment a priority on the world’s agenda, but also delegates from 178 countries attended, including many prime ministers and presidents, making it the largest conference ever held.
The United Nations Conference on Environment and Development, also called the Earth Summit, was held in June 1992 in Rio de Janeiro, Brazil. There were representatives from 178 countries who attended the 12-day summit.
The Outlook
The environmental outlook for the future is mixed. In spite of economic and political changes, interest and concern about the environment remains high. Air quality has improved in some areas in the developed world but has deteriorated in many developing countries, and problems of acid rain, CFC’s and ozone reduction, and heavy air pollution in Eastern Europe still need solutions and action. Until acid rain is under control, loss of the life in northern lakes and streams will continue, and forest growth will be affected.
Water pollution will remain a growing problem as increasing human populations put additional pressure on the environment. Seepage of toxic wastes into underground water sources and the passage of salt water into coastal freshwater reserves have not been stopped. Exhaustion of natural water supplies in many parts of the world and growing demand for water will bring severe problems to agriculture, industry, and cities. This shortage will force water-usage restrictions and will increase the cost of water consumption. Water could become the “energy crisis” of the early 2000s.
Pollution of coastal and fresh water along with over-harvesting has so reduced the fish population, that five to ten years of little or no fishing will be required for stocks to recover.
Without a lot of effort to save habitats and stop poaching and the illegal wildlife trade, many wildlife species will become extinct. In spite of our knowledge of how to reduce soil erosion, it is still a worldwide problem, because too many farmers and developers show little interest in controlling it. Finally, the destruction of wild lands, could result in massive extinctions of animal and plant life.
