Last modified on 16 February 2015, at 17:19

FHSST Biology/Contents/Index/ES/Human Influence/Air

Oil extractions and gas flumes kill birds. Burning of fossil fuels emits C02 into the environment. Fossil fuels: Most air pollution is caused by the burning of fossil fuels for combustion energy. The three chemicals that most pollute the air are carbon monoxide, sulphur dioxide and hydrogen sulphide. Carbon monoxide is mainly produced by petrol/diesel vehicles. The percentage of carbon monoxide by car pollution is small compared to pollution due to natural causes. Carbon monoxide is seen as a poison to humans rather than bad for the ecosystem. Sulphur dioxide is much more toxic and originates from the combustion of coal and fuel oils, at sulphuric acid plants, and in the processing of metal ores containing sulphur. It is converted to a form of sulphuric acid in the atmosphere which is precipitated onto the Earth and is highly toxic to plants and causes corrosion to various manmade materials. This ‘Acid Rain’ is common in industrialised areas and at high levels can cause inflammation of the respiratory tracts of animals and people. Hydrogen Sulphide are sometimes by-products of petroleum processing, coking and paper making. Hydrogen sulphide may also be produced by anaerobic bacteria in sewerage. This pollutant is viewed more as a nuisance rather than a serious environmental pollutant.

Pollution by particulate matter: produced by industrial processes, auto exhausts, bare soil and fires. Also dust accumulates in cities and areas suffering from erosion due to overgrazing. Soot from combustion processes. This particulate matter suspended in the atmosphere causes a lowering of visibility, soiling of paintwork, corrosion of manmade materials. Many costs accrued to public health because of the aggravation of brachial illness (look up effects to townships) . The future effects of particulate matter in the atmosphere may cause some global cooling although some global warming is also possible.

Smog: Nitrous oxides are emitted into the atmosphere through the combustion of coal, oil or natural gas in power plants and pollutants from internal combustion engines. Incomplete combustion of the auto – engine is by a factor of 6 the most aggravation polluter. Nitrogen dioxide is a respiratory irritant and also absorbs sunlight, especially in the blue wavelengths, and so appears as a yellow-brown gas. It absorbs sunlight and through a chemical reaction produces ozone, formaldehyde and nitrous oxide. The high ozone levels in some cities cause respiratory problems amongst some people. Smog has also affected crops and forests. Smog also damages infrastructure.

Because of the dynamic nature of the atmosphere, pollutants are often transported far from their source. Most sulphur compounds end up in the ocean with no consequences. Some substances seem to pose more of a threat however. One of the more worrying effects is the more efficient transmission of solar radiation, leading to fears of global warming and the increase of skin cancer from UV radiation. Chlorofluorocarbons are one such substance that is released into the atmosphere due to refrigerator cooling systems and aerosol propellants. (Show pic of CFC free cans!) This substance breaks down very slowly. The production of CFCs has been declining in recent years, and is thought to be less of a problem then carbon dioxide. Nitrous oxides produced in the atmosphere from aircraft also seem not to pose a significant threat compared to those of carbon dioxide. Carbon dioxide concentrations have been increasing in the atmosphere since the lat 19th century. It is estimated that 50 – 60 % of carbon dioxide lands up in the sea and the rest goes into terrestrial ecosystems via photosynthesis. The levels of carbon dioxide can be maintained or reduced by protecting and planting forests. Carbon dioxide acts to let in solar radiation but reducing the outward movement of solar radiation, causing a global warming effect. Even slight shifts in temperature can have wide ranging consequences in shifting the boundaries of deserts and suitable cultivation areas. The melting of polar ice caps could also bring about a rise in the sea level.

Something that can be classified as land, air and water pollution: Pesticides: Used to eliminate man’s competitors and also to kill viruses and bacteria that are detrimental to our health. Ideally toxins used as pesticides should break down into harmless substances after they have done their job. In reality though, some substances persist in the environment in a toxic form. Through natural selection, some pest organisms and pathogenic life forms are becoming resistant to pesticides/antibiotics. For example, the malaria carrying mosquito Anopheles is showing some immunity to DDT. A bacteria strain, known as Staphylycoccus, is often unaffected by penicillin. Some pesticides accumulate in the environment, with concentrations becoming more concentrated in organisms higher up on the food chain (example of whales etc.). Chemicals such as copper sulphate have been used for hundreds of years as a pesticide. Sodium chlorate is a well-known weed killer. Modern pesticides are more often complex organic molecules. The most widespread of pesticides are those of the organochlorine group. DDT belongs to this group and was first used in a widespread fashion after the second world war. DDT is highly toxic to most species of insects, but fresh water fish are also vulnerable. All pesticides in this group are long live(10-15 years) and persist in food chains, causing sub-lethal and lethal effects at various - trophic levels. (Example of DDT being at a universal concentration in the environment.). DDT appears to be distributed across the whole world, even in Antarctica. DDT appears to make the egg shells of some birds too thin and the eggs break. Low dosesof DDT affect the behavior and reproduction of fish and amphibians. Although DDT is the most well known of the organochlorine pestices, there are more such as BHC, dieldrin, adlrin, endosulphan and heptachlor which are as toxic. Although most of these have been banned in many countries, substitutes have been developed that are more specific and are less persistant. Interestingly, most people in the USA are not fit for human consumption as they have a too high concentration of DDT.

Noise pollution: relevance for chapter 2. Air, water. Noise levels in many urban industriased areas known to be bad for peoples health.

Warefar: Chapter 2: Air and land and water. Warfare is usually about resources and pre-empts rapid use of these resources. Iraq war and burning of oil wells. Vietnam and destruction of forests. The transmission of disease when in North America blankets infected with smallpox were sent as gifts to the Indians. Zimbabwe, civil war and shooting of wild animals. Vietnam and bombing of rural areas – destroyed trees and crops , made soil more arid and killed wildlife and some erosion. Biocides were used in large scale in Vietnam in order to deny cover and sustenance. About 10 percent of South Vietnam was sprayed one or more times. Forest is taking a long time to re-establish and hampered by high water table. At least 3 sensitive species were affected and malerial mosquitos thrived.

Nuclear explosion will cause immense damage and contamination of ecosystems. The initial explosion will destroy much of an ecosystem, but also miles around the site there will be large amounts of radiation. This radiation will create malformations and mutations in animals due to mutations of genes, which produce important proteins. These malformations could range from impotence to life-threatening scaring. Such consequences can destroy entire ecosystems within months if not days.

Conclusion to chapter 2: Pollution is causing ecosystems to become dominated by generalist species- forest – hardy shrubs and weeds, sensitive phytoplankton to sewage plant algae , diversity In birds, plants and fish to much lower diversity. Dominated by hardy species. From stable populations to instable populations of pest species – certain insects and rodents. Ecosystems that require constant tinkering.