Doing a Bit for Prevention of Acid Rains

Some lakes in Sweden and the USA ( Adirondack Mountains) were treated by lime as an experiment in order their acidity to be reduced. As lime has calcium carbonate in its base, it is used in a grind or powder form mixed with water. Liming reduces the acidity of a lake and provides a certain reserve of resistance (buffering capacity) in relation to the future acidic addition. If the water exchange in a lake or a pond is fast , i.e. the rate of inflow and out flow is rather large, then liming may be repeated every other or every two years. As the majority of lakes in Adirondack Mountains are difficult to approach by roads, then the use of helicopters and airplanes will make the liming operation a bit more expensive. The speakers, speaking on behalf of the electrical and coal companies, recommend the described approach.

Liming can also be applied to save forests perishing from acid rains. Liming retards the rate of acidification in soils and increases a pH value. However, the growth of trees on limed soils is supposed to be far from optimal. In Schwarzwald (Germany) foresters have introduced into soil a mixture of magnesium sulfate (800 kg per 1 hectare ) and lime (2270 kg per 1hectare). After this treatment trees suffering from the damage considered as not severe began to recover. Foresters are sure that this process may give good result 5-10 years later provided that air is kept clean.

The fact, that trees recover after such processing allows to suspect that mentioned above causes of damage and losses of forests are likely to be true. Magnesium, is supposed to be washed out from soil (as its addition makes use), and soil acidification is harmful ( as liming brings about a positive effect).

Technical means of air purification, measures against acid rains and forests losses are well known. They are the same as those to be used to control sulfur and nitrogen oxides emissions into the atmosphere . Power stations should be equipped with scrubbers to remove sulfur oxides, and fossil fuels burning processes should be modified to reduce nitrogen oxides emission.

In 1982 Norway, Finland and Sweden agreed to reduce sulfur dioxide emissions by 30% by the year of 1993 against the level of 1980. Today eight states have agreed to achieve this limit. Denmark, Western Germany, Switzerland, Austria and Canada have joined three countries- pioneers of this initiative. Great Britain, France and Eastern Germany did not commit themselves to such obligation. Canada has determined the 50% reduction of sulfur dioxide emission as a national target without cooperation with the USA. Though the aim was recently proclaimed , the Canadian government has stated levels of control reductions and fines for their default. At the same time authorities of Ontario gave directives to industrial enterprises- the main source for sulfuric gas emission – to take measures for purification of flue gases and wastes in order to reduce their level in 1994 up to one third of the level of 1980. Only four companies are responsible for 80 % of sulfur dioxide emissions in Ontario.

No doubt, automobiles exhaust much less sulfur oxides, but they remain the major suppliers of nitrogen oxides. Catalytic converters and improved engines are applied to reduce nitrogen oxides emission by a motor-vehicle transport. (the problem of vehicle nitrogen oxides emission was discussed in chapter 9). In the USA these measures against air widely used, but constantly growing motor vehicles traffic slows down the progress in reaching definite standards of air quality.

In contrast to the USA, European countries neglect methods of pollution control of exhaust gases in motor transport . Though European automobile industry possesses all the necessary technologies - automobiles exported to the USA are equipped with required devices. As a respond to shocking reports and forests destruction from air pollution Germany tried to introduce into practice the use of lead-free fuels and catalytic converters. The term was defined as 1986. But automobile lobby has broken this attempt. Then another term was stated for newly produced cars, depending on their engine power -1988 for big cars and 1992 – for small ones. Automobiles not equipped with exhaust gas control remain in use without any changes till expired.