Below is extract from Conservation & Environmental Management BEN201
POLLUTION
In 1990 a satellite named Voyager 1 was launched from earth and transmitted an image of the earth from a place six thousand million miles away. The image was a bright blue speck, encased in a shimmering diaphanous membrane. This membrane is the life supporting air and water. It has been said that if intelligent life exists way out in space, this is an awesome thought. and at some stage in the future transferring to another planet may be possible for earth people. However, if there is no other life than that on earth, the truth must be faced, for the future there is only one earth.
Due to the negligence by governments and the people they rule, the planet earth has suffered considerable damage. All over the world, we have allowed industry to chemically pollute the precious atmosphere of the planet. It is now time to call a halt, and to come to the realisation that without the life supporting atmosphere, all life on earth cannot be sustained. The pollution of the earth is fast approaching the critical levels where life supporting systems will break down. However, all is not lost yet, if controls and measures are carried out it is possible to halt the deterioration and possibly reverse it.
The shield of gases shelters the earth from the excessive amounts of ultraviolet radiation enabling life to exist on the planet, and dust particles. Heated by the sun and by radiant energy from the earth, the atmosphere circulates around the earth and modifies temperature differences.
Of the water on earth, 97% makes up the seas and oceans, 2% is ice and 1% is the fresh water in the rivers, lakes, ground water, and atmospheric and soil moisture. The soil is the thin mantle of material supporting life on earth. It is the product of climate, parent material such as glacial till and sedimentary rocks, and vegetation. Dependant upon all these are the living organisms of the earth, including humans. Plants use water, carbon dioxide and sunlight to convert raw materials into carbohydrates through photosynthesis. Animal life, in turn depends on plants.
The atmosphere of the earth comprises 78% nitrogen and 21% oxygen. The remainder is composed of several gases, the most important being carbon-dioxide. Carbon dioxide only composes 0.03% of the atmosphere of the earth, but it is the key to the whole system. Plants absorb carbon dioxide to convert sunlight into food. This process is called photosynthesis. In this process the plants give off oxygen. The animals of the planet, including humans, cannot live without oxygen. The plants and animals when using oxygen, exhale carbon dioxide, thus completing the cycle. This is a very good arrangement of the workings of nature. The system is simple and efficient, and if not interfered with will sustain life indefinitely. This serves to stress any interference, by man, in the make up of the atmosphere, could be fatal in the long-term, and unpleasant in the short-term.
Due to progress made by man through the centuries, and in particular the industrialisation of the last two centuries, the quality of atmosphere, the land and the waters of the earth have deteriorated.
Throughout its long history, the earth has changed slowly. Continental drift separated landmasses, oceans invaded and retreated from the land. Mountains rose from the earth’s surface and were worn down by climate and time, thus depositing sediments along the edges of the seas. Climates changed, they warmed and cooled in succession. Life forms appeared and disappeared from earth as the climate changed.
The last major environmental event in the history of the earth occurred during the Pleistocene epoch, between 2.5 million and ten thousand years ago. This is also known as the Ice Age. The subtropical climate was destroyed and the face of the Northern Hemisphere was reshaped. Ice sheets advanced and retreated four times in North America and three times in Europe. The temperature swung between cold and temperate, and this influenced vegetation and animal life. The environment existing today was ultimately formed. The epoch following the Pleistocene is known as the Recent, the Postglacial epoch and the Holocene. During this time the environment on earth has remained essentially stable.
The species Homo sapiens, or as the species is commonly known, humans, appeared later in the history of the earth. However, humans have ultimately, extensively modified the environment of the earth, by their activities. Humans are believed to have first appeared in Africa, but they quickly spread throughout the world. Because of their unique mental and physical capabilities, humans could escape the environmental constraints limiting other species. They could change the environment to suit their needs.
At first humans lived in some harmony with the environment, as did the other animals, but their retreat from the wilderness began with the first prehistoric agricultural revolution. Their ability to control and use fire allowed them to eliminate or modify the natural vegetation. The domestication and herding of grazing animals resulted in overgrazing and soil erosion. In addition, the domestication of crops led to the destruction of natural vegetation to make space for crops. The demand for wood for utilising for fuel led to denuded mountains and depleted forests. Wild animals were slaughtered for food, and destroyed as pests and predators.
While the human population remained small and human technology was modest, the impact of humans on the environment was localised. However, as populations increased and the technology improved and expanded, more significant and widespread problems arose. After the Middle Ages, rapid technological advances culminated in the Industrial Revolution, involving the discovery, use and exploitation of fossil fuels, and in addition, extensive exploitation of the mineral resources of the world. With the onset of the Industrial Revolution, humans began in earnest, to change the face of the earth, the nature of the atmosphere, and the quality of the water. Currently, unprecedented demands on the environment from a rapidly expanding human population and from advancing technology are causing an accelerating and continuing decline in the quality of the environment and its ability to sustain life.
Industrial Pollution
In the previous section, mention was made of the carbon dioxide–oxygen cycle. This section commences with a wider analysis of this process.
Pollution can be defined as: The unwelcome concentration of substances which interfere and upset the capacity of the environment to behave naturally. These substances are detrimental to the well-being of humans and other living things, be they flora or fauna.
If an ecosystem is undisturbed, all the substances are processed through an intricate network of biochemical cycles. During these cycles, substances are taken up by the plants.
These substances move through the food chain to larger and more complex organisms. On the death of these organisms, they decompose into simpler forms which are reused when they are taken
up by the plants. The substances that can be used by the biological systems of the environment are called biodegradable substances.
Pollution occurs when the environment becomes overloaded beyond the capacity of the normal processing systems. These processing systems can break down in several ways, examples of which are given below:
• If there is an excess of substances that are normally helpful, such as the nutrients nitrogen and phosphorus.
• If there is an excess of substances that in small amounts are harmless. It is possible that these substances are important or useful, in normal life, but in large concentrated amounts they can become toxic. One example is the mineral copper. Copper is necessary, in small amounts for healthy plant growth, but in large quantities it becomes a pollutant.
• Synthetic compounds, or man made compounds. These substances are often poisonous in the environment, and trace amounts can often have toxic effects. Examples are DDT and dioxin.
• Substances that are not in any way, or any amount biodegradable, such as plastics.
Some of these pollutants will kill living organisms outright. Other sub-lethal pollutants do not kill, but they cause long-term biological damage because they interfere with the reproductive systems of organisms, or make them vulnerable to disease.
TYPES OF POLLUTANTS
Pollutants can be grouped according to the main ecosystem they affect. However, it should be noted that one pollutant often affects more than one ecosystem. These groupings are shown below:
Air Pollutants
Pollutants that effect air quality include the following:
Sulphur dioxide: This is caused by the burning of fossil fuels. It causes acid rain and respiratory problems for mammals including humans, eg. forest fires in Malaysia.
Nitrogen oxides: These are caused by vehicle emissions (Internal combustion engines).
Volatile hydrocarbons: These are also caused by vehicle emissions.They combine with nitrogen oxides to form photochemical smog. These emissions cause respiratory problems.
Carbon monoxide: This is caused by unburnt molecules of fuel and comes from vehicle emissions. This gas restricts oxygen intake, causes drowsiness, headaches and ultimately death. It affects plant life.
Carbon-dioxide: This is caused mainly by the burning of fossil fuels. It is conducive to global warming. Carbon dioxide has increased in the earth’s atmosphere mainly due to increased burning of fossil fuels. The amount of carbon dioxide in the atmosphere remained stable for centuries at about two hundred and sixty parts per million, but over the past century it has increased to three hundred and fifty parts per million. The significance of this change is the potential for raising the temperature of the earth through the process of global warming. Carbon dioxide in the atmosphere prevents the escape of outgoing long-wave radiation from the earth to outer space. As more heat is produced and less escapes, the temperature of the earth increases. If this trend continues, it could have profound environmental effects. It would speed up the melting of the polar ice caps and raise sea levels. This would change the climate, both locally and globally. It would alter natural vegetation and affect crop production. These changes, in turn, would have an enormous impact on human civilisation.
Since the year 1850, there has been a mean rise in global temperature of approximately 1 degree Celsius. Some scientists have predicted that a rising level of carbon dioxide and other greenhouse gases will cause the temperature to continue to increase. The estimates range from 2-6 degrees Celsius by the middle of the twenty first century.
Chloroflurocarbons (CFCs) eg aerosols, refrigeration, air conditioning, and foam blowing industries: These substances can destroy the earth’s protective ozone layer.
Methane: This is produced by decomposing rubbish (e.g. large quantities produced from rubbish tips), sewerage treatment plants, and from grazing animals such as cattle (e.g. feedlots).
Noise: Caused by industry and traffic. It is very stressful and can ultimately negatively impact hearing.
Most of the dangerous pollution in the atmosphere is invisible. Treating pollutants properly before their release can be expensive. Unfortunately the cost to the environment of releasing such pollutants is seldom considered. Not much of the highly dangerous pollutants are emitted by accident. They are usually emitted purposefully. Legislation against the emission of pollution exists, but sadly, far too many manufacturers seem to sidestep the issue and there are often no proper inspections and controls in spite of legislation, or penalties are not severe enough to deter manufacturers from deliberately emitting such pollutants.
In developing countries, more intensive monitoring is being carried out and these industries polluting the environment are forced to reduce the pollution.
Fresh Water Pollutants
Pollutants that affect fresh water include the following:
Sewage, inadequate sanitation: The pathogens in sewage can cause such things as typhoid, cholera and gastroenteritis. The nutrients in the sewage can cause eutrophication, killing animal and plant life in the water by deprivation of oxygen.
Fertilisers: These are leached out of the soil, or washed across the soil surface. They enter rivers, streams and lakes casing eutrophication, especially phosphorus (eg from superphosphate).
Sediments: This is caused by poor land management which leads to erosion. The sediments can settle in waterways and estuaries and smother aquatic organisms, while heavy sediment deposition can affect boat passage in waterways, lakes and estuaries. Sediment in suspension can reduce the amount of light reaching organisms, and reduce the quality of the water for domestic consumption (showers, drinking), agricultural use (e.g. irrigation, watering stock), and industrial use. The quantity is reduced by the filling of dams, rivers and lakes.
Agricultural chemicals (e.g. pesticides, veterinary products, growth promoters): These, or their ‘breakdown’ products (chemicals produced as the product breaks down), can be toxic to both plants and animals. Many interfere with the reproductive processes of birds and mammals. Many are extremely toxic to fish. Some reach waterways in surface run off, others by direct spray (poor spraying practices).
Extensive use of synthetic pesticides derived from chlorinated hydrocarbons (e.g. DDT, Dieldrin, Endrin) has had disastrous environmental side effects. These organochlorin pesticides are highly persistent and they resist biological degradation. They are relatively insoluble in water. They cling to plant tissues and accumulate in soils, the bottom muds of ponds and streams, and in the atmosphere. Once volatised, the pesticides are distributed worldwide, and in doing so, they contaminate wilderness areas far removed from agricultural regions, and even the Arctic and Antarctic zones.
Although these synthetic chemicals are not found naturally in nature, they nevertheless enter the food chain. The pesticides are taken in by plant eaters, or they are absorbed through the skin by such aquatic organisms as fish and various invertebrates. The pesticide is further concentrated as it passes from plant eaters to meat eaters, becoming more highly concentrated in the tissues of animals at the high end of the food chain, like the peregrine falcon, the bald eagle, and the osprey. Chlorinated hydrocarbons probably interfere in the calcium metabolism of birds, causing thinning of the shells, and subsequent reproductive failure. As a result, some predatory and fish eating birds have been brought close to extinction.
Because of the dangers of pesticides to wildlife and humans, and because insects have developed resistance to many pesticides, the use of halogenated hydrocarbons is declining rapidly in the Western world, although large quantities are still shipped to developing countries.
Toxic metals: These are by-products of industry. They are a threat to both health and life of both fauna and flora. Significant quantities of lead can also enter waterways through the activities of hunters (e.g. duck hunting) and fishing (lead weights).
Toxic substances: These are chemicals and mixtures of chemicals whose manufacturing, processing, distribution, use and disposal present an unreasonable risk to human health and the environment. Many of these toxic substances are synthetic chemicals that enter the environment and there persist for long periods. Major concentrations of toxic substances occur in chemical dump sites. If chemicals seep into soil and water, they can contaminate water supplies, air, crops and domestic animals. They have even been associated with human birth defects, miscarriages, and organic diseases.
Despite the known dangers, the problem is not decreasing. In a recent period of fifteen years, more than four million new synthetic chemicals were manufactured, and new ones are being created at the rate of five hundred to one thousand per day.
Marine Pollutants
Pollutants that affect marine life include the following:
Sewage: inadequate sanitation: This has the same effect as in fresh water and is detrimental to both animal and plant life.
Fertilisers: These are washed down by rivers into the sea, and cause eutrophication.
Oil spills: These spills smother marine plants, birds and other animals, and can cause death. They also pollute beaches when the oil is washed ashore. This is not only an eyesore and an inconvenience. It also kills marine shore plants and animals (e.g. seals, otters, penguins).
Plastics: These can cause the death of marine animals. The animals swallow the plastic causing blockages in the digestive system, with subsequent death. eg dolphins mistaking plastic bags as jellyfish.
Pesticides: These are from agricultural and health services (e.g. mosquito control programs). They interfere with the reproductive processes of birds and mammals. Some may cause cancers, and other health problems.
Land Pollutants: Pollutants that contaminate land include solid wastes. Solid waste is classified as hazardous (e.g. radioactive, pesticides, medical poisons, heavy metals including mercury, lead, zinc and chrome) or non-hazardous (e.g. domestic, mining, industrial, scrap metal).
• Hazardous waste is health and life threatening to plants, animals and humans.
• Non-hazardous waste is unsightly, and its disposal takes up much space, labour and time.
