Acid Rain in Europe

Since they can be carried many hundreds of kilometers by winds, acid pollutants emitted in one country may be deposited as acid rain in other countries. As industrialization expanded across Europe during the 1970 and 1980s, with the use of tall chimneys in industry and power generation increasing, acid deposition became a particularly prevalent problem.

Within Europe, emission of air pollutants vary greatly, depending upon many factors such as the size of population, the degree of industrialization, pollution control equipment used, agricultural practices applied, the number of road vehicles and political attitudes on environmental issues.

Across Europe the amounts of sulfur dioxide and nitrogen oxides being emitted from a country were found to be different to the amounts of acidic pollution being deposited there. Some countries were emitting only small quantities of pollutants yet deposition was observed to be several times greater, for example in Norway, Sweden, Austria and Switzerland. Other countries such as Bulgaria, Italy, the Czech Republic and the UK emit more pollution than is deposited in their country because of prevailing wind directions.

Acid Depositions in Canada and British Columbia

The problem of acid deposition in Canada tends to be localized to the east of the Manitoba border with Ontario. This area of Canada has a large number of industries causing the release of acid substances into the atmosphere. This area is also influenced by pollution from industrial areas in eastern United States.

Researches have shown that almost half of the acid deposition that falls in southeastern Canada is due to combustion from factories in seven states: Ohio, Indiana, Pennsylvania, Illinois, Missouri, West Virginia, and Tennessee.

Habitats on the west coast of Vancouver Island and coastal mountainous regions have the lowest potential for neutralization.

Large amounts of acid-forming pollutants are created in British Columbia. Most of the nitrogen oxide emissions are created from the combustion of fuels by vehicles. Many industries in British Columbia release sulfur dioxide into the atmosphere including natural gas processing plants, pulp mills, smelters, oil refineries and power plants. Data from recordings stations in several cities indicate that sulphate deposition levels from these sources are well below the eastern Canadian standard developed for the protection of moderately sensitive aquatic systems. Measurements of acidity indicate that precipitation falling in British Columbia generally has a pH similar to naturally occurring rainwater with no pollutants. Finally, a province wide survey of over 750 lakes between 1977 and 1986 found acidic 10 lakes. Subsequent investigations of these 10 lakes revealed that their acidic nature was due to natural causes.

Industrial Emissions Control

Acidic emissions of sulfur dioxide and nitrogen oxides arise from many industrial sources as a result of combustion processes. Industries also emit nitrogen oxides which can also cause rainfall to become more acidic. There are many technologies which can be used in industry to reduce the emissions of pollutants to the atmosphere and these can be applied before, during or after combustion.

Examples of pre-combustion sulfur control technology (removing sulfur before burning) include coal scrubbing and oil desulfurisation.

Another removal process is to change the design of the boiler and to install pressurized fluidized bed combusts (FBC) which removes sulfur from coal during the burning process. Another process which removes sulfur dioxide from coal during combustion is the Integrated Gasification Combined Cycle. Coal is gasified under pressure with a mixture of air and steam which results in the formation of gas which can then be burned to produce electricity.

One of the post-combustion sulfur controls (removing sulfur after burning) is Flue Gas Desulfurisation (FGD).

In 1979, the United Nations Economic Commission for Europe (UNECE) implemented the Convention on Long-Range Transboundary Pollution. In 1985 most UNECE members adopted the Protocol on the Reduction of Sulfur Emissions, agreeing to reduce sulfur dioxide emissions by 30% (from 1980 levels) by 1993. This was called the 30% club. All of the countries that signed the Protocol achieved this reduction, and many of those that did not sign, have met these reductions.

In 1988 a Directive was introduced for European Community (EC) countries which required power stations to reduce emissions of sulfur dioxide and nitrogen oxides.

There is a close connection between sulfur and nitrogen emissions , asid depositions, an increase in water acidity and decrease in its alcalinity.