Acid rain study

a) Acid rain is a term used to describe wet forms of acid pollution that can be found in rain, snow, fog or water vapour. This type of rainfall usually has a lower pH (below 5.6 average) when acidic. It is formed when secondary pollutants formed from the oxidation of nitrogen oxides of sulphur dioxide are released into the atmosphere. These substances react with the surroundings and react with other gases in the atmosphere to form acids, which can eventually incorporate with water vapour in the clouds to form sulphuric and nitric acids.

The major substances which produce acid rain is sulphur dioxide (SO2) and nitrogen oxides (NOx). Natural and human actions are responsible for the production of these pollutants. The natural processes are mainly unavoidable and include decomposition of organic matter, volcanic eruptions that release sulphur dioxide and degassing from oceanic plankton. The volcanic eruption in Philippines in 1991 resulted in a temporary decrease of global temperatures for more than two years.

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Acid rain has been recognised for centuries but it was not known until the 19th century that these were linked with human actions. It is known to be caused from emissions released into the atmosphere from factories burning fossil fuels such as coal and oil. In the Victorian times, coal fires released huge amounts of sulphurous fumes through the chimneys as well. Harmful substances are also released from exhaust fumes which contain sulphur dioxide and nitrogen oxide which form acids in the atmosphere.

Dry acid deposition can be formed when sulphuric acid in the atmosphere condenses which can result in fogs, mists and hazes over urban areas.

b) The table showing the acidity of commonly occurring substances in order starting from the most alkaline:



Oven spray cleaner


Ammonia solution


Kitchen surface cleaner


Sea water


Distilled water




Washing up liquid


Pure rainwater


Acid rain








Lowest recorded acid rain


Dilute nitric acid


Acidic substances such as sulphuric acid can react easily with metals such as potassium. When it reacts it can be dangerous and can burn and destroy the metal completely. Acidity is measured using a pH scale from 1 to 14.An alkaline substance would about 9 to 14 and an acid substance 1 to 4. Neutral substances are of pH value 7. The acid in acid rain is very weak and dilute as it is mixed with a large amount of water in the atmosphere. That is why it cannot actually burn us. Acid rain with a pH value below 2 can be considered 5000 times more acidic than normal rainwater and this has occurred in West Virginia in 1978. Normal rainfall is normally slightly acidic as it is mixed with carbon dioxide, oxides of sulphur and oxides of nitrogen, which occur naturally in the air forming weak acids.

c) On the next page…

d) The type of soil a plant grows in can determine the growth for the plant. Many soils have properties which can decrease an impact on it such as being able to neutralize acids. This is because they have a lot of lime in them which is alkali and can neutralize these acids. Soils made of siliceous minerals or weathered bedrock are not so good at this job. In these kinds of soils the increase in acidity can result in leaching of several important nutrients such as calcium, potassium and magnesium. Leaching occurs as a form of filtration of useful nutrients from soils. A deficiency in these nutrients can result in poor root and stem growth.

The increase in mobilisation of toxic metals can interfere in the active uptake of nutrients into the roots which can eventually damage them. These metals include Lead (Pb), copper (Cu), cadmium (Cd) and aluminium (Al). Reductions in soil pH can prevent the growth of germinating seeds and the growth of young seedlings. Many significant soil organisms require the correct pH to survive. Acid rain can result in a pH of below 6.0, therefore destroying these organisms. This can then result in decomposition which is known to release vast amounts of sulphur products which could form more acid rain.

Acid rain releases metals into the soils, which can be transferred through the roots, and into the plant. Some of these plants could be vegetables which would later be consumed by humans. The results of acidification on the top soil can lead to reduced intake of water and nutrients, damage to fine root hairs and decomposition slowed down thus less nutrients for plants. The decline of trees in areas such as Scandinavia and Brazil have resulted in nutrients such as Magnesium and Calcium being washed away as there is no canopy to protect the undergrowth. This has now led to soil erosion and loss of humus in soils. The infertile soil has resulted in this decline of plant growth in these areas.

Task 2 – Changes in UK emissions

a) The greatest source of sulphur dioxide in 1981 was in power stations with nearly 3000 tonnes of emissions. The greatest source of sulphur dioxide in 1991 was in power stations as well with just over 2500 tonnes of emissions. The greatest source of nitrogen oxides in 1981 was in power stations with nearly 1000 tonnes of emissions. The greatest source of nitrogen oxides in 1991 was road transport with nearly 1500 tonnes of emissions.

b) In the 1990’s more technology was introduced and the population increased so more vehicles were used. The public transport is not as efficient so people rely on vehicles. There are also more motorways and roads since the 19th century and the world since then has developed greatly. The number of power stations across the country increased so more sulphur dioxide and nitrogen oxides were released than in 1981. Although improved technology has allowed us to reduce certain types of air pollution, the emissions released cannot all be reduced. Most people need electricity to survive and power stations are very efficient in this way. Other sources of renewable energy can be expensive and time-consuming to produce the same amount of energy in the same amount of time.

c) In 1981, the emissions of nitrogen oxides (NOx) were low in sources such as domestic, commercial/public, refineries, other industry, shipping and other transport. Power stations and road transport were emitting nearly 1,000 tonnes. At that time, cars and roads had rapidly improved and developed for the growing population. Power stations were found to be very efficient and less time-consuming to product energy. Ten years later, in 1991, the emission of nitrogen oxides increased to nearly 1500 tonnes in road transport as the population continued to grow. The amount emitted in power stations decreased slightly possibly because the risks to the environment were noticed and alternative energy solutions were sought.

In 1981, the emissions of sulphur dioxide (SO2) were extremely high in the uses of power stations and higher in all other areas than nitrogen oxides. Power stations were efficient and reliable and there were not many other alternative energy producers at the time. The amount emitted in road transport was much lower than nitrogen oxides and did not increase by many ten years later. Power stations were the most emitters at this time and still are in 1991 although decreasing slightly. Shipping has increased slightly. Other transport, refineries, domestic and commercial/public have all decreased slightly.

d) The differences within the eight categories are that now, alternative energy producers have been sought and used to reduce emissions of sulphur dioxide and nitrogen oxides. Power stations were and still are seen to emit the most of the pollutants and road transport could rapidly catch up. The population is increasing, technology is improving and more people require energy and vehicles. Some people do not think other forms of transport as very efficient such as railways and vehicles are used more widely. Factories and companies are always considering alternative solutions but could in the next ten years be level with road transport. Domestic pollution does not release as much pollution as improved gas-fires have been developed to release less pollution since the early 1900’s when coal-fires released huge amounts of emissions of sulphur dioxide.

e) “Acid rain is the creation of human activity.”

I agree that most forms of acid depositions are man-made from polluters such as road transport and the burning of fossil fuels. These gases are released into the atmosphere and can have horrendous effects of plant, water, fish and buildings. The long-term effects of these pollutants on the atmosphere can result in global warming and many scientists believe there will be an increase in sea levels, as polar ice caps will melt due to the altering climate.

Human sources include exhaust fumes from vehicles, smoke from factories, and the waste gases produced by heating our homes and other buildings. These man- made sources increased dramatically during the 20th century, due to rapid population growth in which people required more energy and more fossil fuels were burned and more power stations were built for this purpose. The development of new materials and products, which can improve our lifestyle, are also polluting such as improved cars and aerosols.

Human activity is responsible for 65 million tonnes of sulphur dioxide deposited into the atmosphere in 1985 in contrast with natural sources which are responsible for only 25 million tonnes a year. It is accountable for 21 million tonnes annually of nitrogen oxides and this is about the same for natural sources with 15-20 million sources a year. This shows that sulphur dioxide is major hazard to our environment and most of it is man-made. Nitrogen oxides are responsible for the same as natural but if all this were decreased we would not have as much polluting our atmosphere. It is about time we realised the pollution we are causing to our environment.

Task 3 – Acid rain between countries

a) On the next pages…

b) My graph shows that Germany, United Kingdom, Poland and Italy have the highest emissions and Poland, Germany, United Kingdom and France have the highest depositions. Sweden, Austria, Switzerland and Norway have the lowest emissions and Belgium, Netherlands, Denmark and Switzerland have the lowest depositions. My graph tells me that depositions are normally found thousands of miles away from where it was produced and can have severe effects where deposited. Also countries with a larger population are also releasing more emissions.

c) On the next pages…

d) My graph on the percentages of sulphur received in European countries tells me that areas across Eastern Europe are suffering the most. United Kingdom, which emits the most sulphur dioxide, seems to receive the less because all of its pollution is being blown by the wind across Europe. This makes countries like Norway, Austria, Sweden and other parts of Scandinavia very vulnerable to acid deposition. Norway, Austria, Sweden and Switzerland have the highest percentage of sulphur received in which most of it probably does not originate in these countries at all. Czech Republic, Italy, Germany and United Kingdom have the least sulphur dioxide received from other countries.

e) The explanations for the differences between the highest and lowest figures on the graphs and map 1 are that MEDC’s such as Germany and United Kingdom have plenty of money to build power stations and buy fossil fuels from abroad. This is how huge amounts of emissions are released, mainly from MEDC’s building so many power stations. Smaller countries, with the least population like Norway want to preserve their environment and trees but are the ones suffering the most of the depositions. It is mainly the countries with a rapidly growing population needing more energy and releasing more pollution.

Countries, as in my graph, like Austria and Norway have higher depositions than emissions because countries like the USA and UK are having their emissions blown by the wind thousands of miles across to Eastern Europe. Countries similar to Germany, as in Map 1, have their emissions blown to the south-east in Summer to countries like Poland and in winter blown to countries like Denmark and this is how many parts of Scandinavia are polluted.

United Kingdom’s emissions get blown across to Norway and Sweden in summer and winter and also to Belgium and Netherlands. Up to 20,000 thousand emissions get blown across Eastern Europe every year from the UK and up to 30,000 from Germany as well. Countries like Austria, Switzerland and Norway release less than 1000 tonnes of sulphur but the distribution of emissions from other countries do deposit in these countries. Acidity levels in Eastern Europe have been as high as 4.0 due to acid rain in these areas. Poland, Czech Republic and Italy have their emissions blown southwards.

Task 4 – Global problems of acid rain

“Is acid rain a global problem?”

Acid rain is a global problem and requires international co-operation to help solve the problem. It is a global problem because air currents that produce our daily weather also carry pollutants over long distances. When pollution travels between countries like this it is known as trans-boundary air pollution. Pollutants that they have not produced themselves can affect the people and environment in far-off places. For example, polar bears and the Inuit people in the Artic have high levels of chemical contamination that has originated thousands of miles away. The greatest source of acid rain is from MEDC’s such as UK and USA and this may be because of their rapidly growing population requiring a lot more energy than other countries like Poland and therefore more power stations are built for this purpose.

Countries need to co-operate with other to monitor and control the amount of emissions emitted. It can be complicated for some countries as they can be unwilling to take responsibility, especially if they are less affected by the problem. It is important that there is international co-operation as acid rain currently affects the whole world and can lead to global warming if not recognised. If one country is the only one willing to reduce the problem it may not take any effect as the emissions from another country can have just as severe effects. Global recognition can help us to reduce emissions altogether so every country will be least affected and least polluting.

There is currently great pressure on the natural resources of our Earth. Developing countries (LEDC’s) currently account for only a small proportion of global pollution but if they develop standards of living similar to that of Europe or USA, it is likely that the world’s climate could dramatically change. Emissions from these now MEDC’s could be blown across to countries like USA and UK that currently produce most of the emissions and suffer the least. There have been numerous reports of effects of acid rain in central Europe and parts of North America with acid levels up to 4.0 pH. This is why, thinking globally can help us to reduce emissions and help neutralize acids and pay for damage in countries that suffer depositions.

Task 5 – Solutions to the acid rain problem

a) The measures that can be taken to solve or reduce the acid rain problem can be sorted into two categories: short-term measures and long-term measures. Short-term measures are used to immediately reduce levels of pollution. Removing lead from petrol and fitting scrubbers to power station chimneys can reduce levels drastically. Long-term measures are used to remove pollutants completely. Scrubbers can be fitted to coal-fired power stations to remove sulphur dioxide and nitrogen oxides before they enter the atmosphere. Modern scrubbers remove 95% of emissions. Also converting power stations to use natural gas to generate electricity instead of coal as natural gas is less polluting and does not emit sulphur.

The use of renewable energy, such as the sun to power solar cars and buildings or the wind to generate electricity does not release any emissions and is useful, as non-renewable energy sources will eventually run out. Denmark, for example leads the world in wind power and export the most wind turbines. Solar power is popular for remote areas and regions across the equator, where the sunlight is at its most. PV cells convert the sun’s energy into electricity and are popular in LEDC’s. Nuclear power is also a cheaper solution as the energy costs less than fossil fuels. There are currently 429 nuclear power stations across Europe.

Vehicle pollution can also be reduced by using unleaded petrol and has been known to reduce emissions by 98% in the USA. Catalytic converters are fitted into the exhaust system of a vehicle. Waste gases leave the engine and pass through the converter where platinum metals cause chemical reactions to convert them into less harmful emissions. They can drastically reduce nitrogen oxide emissions by nearly 80%. More efficient engines or vehicles powered using natural gas, battery-power or fuel cells can travel long distances very cheaply. Engines that are part petrol and part electricity have been recently developed.

Liming acidified lakes can neutralize the acids in lakes and restore the original pH required by the sea creatures. Limestone or lime is added to lakes to reduce the acidity. Over 5,500 lakes in Sweden have been treated in this way. Lime can be added by floating rafts, helicopters or lorries. Changing our lifestyle to reduce our energy consumption can also help but making it too sudden can cause economic problems. It would cost less to adopt long-term measures than the expenses of dealing with diseases and environment damage.

Some governments have also introduced taxes to help control emissions. For example, leaded fuel now costs more than unleaded and there has been a 25% increase in the usage of unleaded fuel as it is less polluting. In Denmark, a tax has been introduced on the amount of SO2 emitted, so now it costs polluters more to buy coal for power stations and cheaper to use less polluting sources such as natural gas to encourage users to change their energy sources.

Incentives have also been considered in Japan and the USA. The government would encourage companies to use cleaner methods by reducing the price or placing a ‘subsidy’ (give you money) on wind, solar or other form of renewable source. PV cells have caused a boom in Japan with an increase of 6,800 solar rooftops alone in 1998.

b) Some countries may be willing to solve the acid rain problem because they consider it a global issue. They have international organizations established to co-ordinate policies on emission targets. Some countries, which are severely affected by depositions from other countries, are desperate to reduce emissions by working with those producing the emissions in the first place.

International co-operation does not always work because if one party is unwilling to enforce agreements then a whole group will not. For example, Indonesia’s government has not enforced an agreement to ban forest fires which emit sulphur dioxides. Also LEDC’s may not be able to enforce laws, as people here are poor and trying to earn a living at any way possible. They feel they no longer need to reduce their emissions due to the extra cost involved in changing to newer power sources which they cannot afford for their countries.

This can create a conflict in MEDC’s where higher targets are given than in LEDC’s. Not all countries are equally responsible for emissions but responsibility should be taken if another is at fault, this did not happen in 1980’s as Britain took little responsibility for its emissions across Scandinavia despite complaints from the Norwegian government.

c) Some countries are working together to solve the problem by enforcing laws and agreements. For example, the United Nations Economic Commission for Europe (UNECE) aimed to reduce SO2 emissions by 30% under the leadership of countries in Eastern Europe. Also some countries are willing to help pay for specialist equipment used to tackle emissions for other countries who suffer their depositions. Japan, after producing huge amounts of emissions affecting China, is paying for the damage and equipment used to monitor acid rain there.

Since the 1970’s, many countries have recognised the effects of acid deposition. Many agreements and targets have been signed, set and reached by numerous countries in this time. In 1983, 19 countries aimed to reduce SO2 emissions by 30% and all the countries met this target. Just recently, the United Nations Framework Convection on Climate Change signed by 160 countries is the largest agreement aiming to reduce greenhouse gases.

d) The best way to solve the acid rain problem for the future is to simply reduce our emissions. There is no reliable solution to reduce or solve the problem; adding lime to lakes will not bring back all the life lost. Most of the emissions do not disappear from the atmosphere for about 100 years so it is important to reduce as much as possible. The main principle is that renewable energy can cost a lot more than non-renewable sources. If we all worked globally to reduce our emissions in the first place, there would not be any further costs. This can be done by changing the way we live and behave and many people are currently against changing their lifestyle, but to save the Earth, is our lifestyle that important?

If emissions were reduced, the ozone hole wouldn’t get larger and the emissions of greenhouse gases wouldn’t affect the Earth as much as natural sources do. Thinking globally can make a big difference to the Earth’s climate as global warming is going to affect the whole world anyway.

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