H2SO4→H++HSO4
Sulphur acid dissociates into H2 and hydrogen sulphur ion, making acidic
Causes of Acid rain
It is mainly since the industrial revolution that the massive increase in air pollution has resulted in increases in acid rain; this is largely due sulphur dioxide and nitrogen oxides in that are found in pollution from industry, coal and oil fired power stations and cars. The effect of smelting metal ore and the increase of airline travel giving out large amounts of carbon dioxide.
The burning of all fossil fuels will result in combustion gasses and other by products such as soot and ash, if these gasses are not treated but simply vented out into the air, (this is a much cheaper option and therefore the one that most power stations and industry use) they will give rise to acid rain because of there high sulphur dioxide and nitrogen oxides content present in them.
The gasses will rise and form into it the acid rain clouds, but the problem will this type of pollution that it may fall as acid rain hundreds or even thousands of kilometres away carried on wind spread currents and jet streams in the high atmosphere. As an example the vast amount of acid rain that falls in Sweden and other northern European countries is caused by pollution created in the UK by heavy industry and fossil fuel burning power stations
ACID RAIN FORMATION & TRANSPORT
There are also natural causes of acid rain such as volcano eruptions, lightning and bacterial action in soils and vegetation, agricultural activity has also had a large effect on the level of green house gas in the environment i.e. methane from sheep and cattle.
Volcanoes and sea spray are typical natural sources of SO2. Lightning is the most common natural source of NOx. Contributions from natural sources are generally small compared to those from human activity.
Effects of Acid Rain
The main effect that acid rain has on humans
Is increasing breathing problems sulphur dioxide and nitrous oxides that are responsible for acid rain increase problems such as asthma and coughs. They can also cause headaches irritation (swelling and redness) of the eyes, nose and throat.
Acid rain also causes millions of pounds worth of damage to buildings and structure to the country each year. The damage the acid rain as on the structures depends mainly on the acidity of the rain, (the more acidic the greater the damage is caused). Acid rain wears rocks down gradually over long periods of time, this can be devastating, causing bridges to collapse or become so unstable they can not been used safely. Acid rain also eats away a statues and houses over a long period of time.
This effect is mainly destructive to the limestone content of the building, bridge etc. but another effect is the corrosion of metals in cars etc.
Acid rain has had a devastating effect on the environment, because it only takes a small increase in the pH of rain water to harm plants and animals that live near areas such as rivers and lakes, This acidic rain can damage plants and trees in several ways, in high concentrations the leaves an the trees and plants are destroyed by the rain simply falling on them, this prolonged defoliation will starve the tree of food and kill it.
The rain will also fall onto the soil washing out ions such as magnesium and calcium this depletion of minerals that are available to the plants and tree will also kill them. As the plants and trees that are most susceptible to acid rain are killed off they leave the remaining ones vulnerable because of soil erosion that is caused by the destruction of foliage.
Animals such as birds and fish that live on or in the rivers and lakes are killed as the water becomes more acidic and toxic metals such as aluminium and mercury are washed out of the chemical compounds in the soils and into the river and lake water.
An example of this can be found in Sweden where almost 10,000 lakes are contaminated with levels of mercury that are so high that people are advised not to eat any fish that are caught in them.
Impact of global warming
Global warming is another problem that may be attributed to pollution, the green house gasses as they are called (carbon dioxide, methane, CFC, s) form a layer in the atmosphere, the sun radiates short wave radiation that passed through them and heats the surface of the earth, as the surface of the earth heats up it radiates long wave radiation back up into the atmosphere, this type of heat radiation is absorbed by the layer or greenhouse gas and some is radiated back down giving the green house effect.
The Green House Effect
This process as been important for life on earth, however now the increase of these gasses due to pollution has lead to the layer becoming larger and stopping more of the heat energy escaping into space, this causes the earth to slowly become warmer.
The effect of this rise in temperature would result in the melting of large areas of pack ice around to Artic and Antarctic and the retreat of the polar glaciers, this will result in massive amounts of water being released into the oceans and result in rise is sea levels that will flood large amounts of low lying land including many capital city’s of the world.
At the present 46 million people live in areas at risk of flooding due to storm surges. Scientists estimate that a 50cm rise in sea levels would increase this number to 92 million and a one-metre rise would put 118 million lives in peril. This figure was based on a current population density and present level of sea defence measures.
The would also put peoples lively-hoods in danger, with crops being covered by the high level of water rising, especially in poorer country’s. Not only this, but there would be a greater risk of disease like malaria, dengue and yellow fever. If the temperature raises the number of people at risk but also rise dramatically with the risk of malaria having a greater advantage. Air pollution and exposure to greater extremes in temperature could lead to greater frequency of asthma and respiratory diseases.
Deserts are likely to become more extreme and result in decreased soil erosion. Mountains glaciers could retreat and inland wetlands would be affected by global warming with resultant changes in habitat for the current species.
There is always an alterative for this, we as human beings could start to counteract the effects of global warming just by being conscious of our actions. We could reduce the amount of energy consumption by making fewer journeys and using better insulation in our homes. This would lessen the need to burn coal and oils, and lead to reduced emissions of carbon dioxide and nitrous oxide.
Environmental groups like Greenpeace and friends of the earth would like to see a switch to renewable and clean sources of energy such as solar, wind and hydroelectric power.
THE GREENHOUSE EFFECT
Global warming is happening however it is not possible to conclude that it is due to pollution, some people believe that it is part of a cycle the earth goes through every tens of thousands of years.
Conclusion
The carbon found in fossil fuels like coal was stored in vegetation in the vast prehistoric forests over millions of years, the carbon in oil was formed in a similar way but from sea creatures under the oceans again over millions of years. This carbon store that has taken millions to form is now being burned as fuel and the carbon it converted into energy and carbon dioxide. This results in massive amounts of new greenhouse gasses being formed faster then the earth’s environment can reduce them by photosynthesis in plants and trees etc.
My conclusion is that there must be an immediate reduction in the emission greenhouse gasses, gasses that form acid rain and CFC’s. The best approach is to reduce the gasses by the conservation of energy but where this is not practical there are many alternatives, for example fitting a catalytic converter to a car will reduce its nitrogen oxide emissions by up to 90% (this will unfortunately also increase the carbon dioxide)
Sulphur dioxide may be reduced from power station etc. by adding chemicals to it during combustion, (limestone) it can be further reduced by treating the combustion gasses with a spray mixture of water and limestone, this does form a saleable by product (gypsum), used in plaster and other building materials.
It is also important to use new technologies that are more energy efficient these include compact fluorescent lamps that can reduce energy consumption by up to 75% compared with traditional incandescent lamps, electrical powered cars, and high levels of thermal insulation in buildings, combined with the increase in renewable energy from wind, wave and solar power. This will reduce the emissions of carbon dioxide, the greenhouse gas most responsible for global warming.
Bibliography
Collins revision guide (GCSE science)
AQA modular science
