Measures to Counteract Harmful Effect of Acid Rain

Rain water is naturally acidic and while falling down, the rain dissolves the carbon dioxide and water naturally present in the atmosphere to form a weak carbonic acid with a PH of 5.6. Burning of fossil fuels and emissions from vehicles and natural sources results in sulphur dioxide and nitrogen oxide combining with the rain to form a stronger acid, in the form of a wet deposition (acid rain, snow or fog) or a dry deposition in the form of dust.

Vital plant nutrients like potassium, calcium and magnesium ions are eroded from the soil surface and toxic aluminium and lead ions that were once insoluble leaches into the soil affecting the health and productivity of plants in that ecosystem. Aluminium washed into lakes, rivers or reservoirs from surrounding land causes algae to bloom and this has severe impacts on the aquatic ecosystem. The lakes also become so acidic that fish are unable to regulate their internal salt concentration and therefore die in masses, depleting their stock. In addition, acid rain can denature proteins and inhibit the enzyme action of tissues and organisms . Invertebrates with exoskeletons are particularly sensitive and may die as the acid dissolves the calcium compounds that form their skeleton.

Acid deposition further causes corrosion to buildings, statues, railway lines, and iron bridges to name but a few. Buildings and statues especially those made of limestone are damaged by acid rain. The acidic water also corrodes the insides of water pipes and causes copper, aluminium and lead ions to be released from the water pipes into drinking water. The drinking water becomes poisonous causing detrimental effect on human health like “diarrhoea in young children and harm to the liver and kidneys” ). Some research has linked Alzheimer’s disease to higher levels of aluminium in the body. Human diseases like Bronchitis, Asthma and Emphysema are exacerbated when acid rain is produced and in addition treatment of these diseases puts a burden on the National Health Service.

Transboundary pollution caused by prevailing wind patterns affects countries where the acid was not produced and leaves an ecological burden on their society e.g. Scandinavia coniferous forest destroyed by acid rain from pollution in other European countries.

Physical Measures

How to counteract effect of acid rain:

• Power stations change fuels by having cleaner coal;
• Fitting of catalytic converters in cars to reduce Nitrogen dioxide;
• Reduction of acidity in lakes by adding calcium carbonate to neutralise the acid;
• Limiting the number of vehicles on the road, a hard one to achieve in most countries around the world;
• Use of alternative energy sources like hydropower, solar, wind or nuclear;
• Attack on flue gases by scrubbing sulphur also known as flue gas desulphurisation (FGD).

Most of the physical measures above have resulted in reduction of acid rain. However how effective adding calcium or liming in order neutralise the acids in the lake has its limitations. It is costly to lime all the acidified lakes and it is difficult to apply to lakes and streams in remote locations. Flue gas desulphurisation has high operating costs, putting a financial strain for Eastern European countries that are heavily reliant on Coal to retrofit their plants unlike in Western Europe, where most plants have been retrofitted.

Legislative Measures

The 1968 Clean Air Act in the UK brought about the basic principle for the use of tall chimneys for industries burning coal, liquid or gaseous fuels to deal with sulphur dioxide that were emitted. Unfortunately, this Act unintentionally transformed the problem of sulphur dioxide from a local pollution problem to a regional one.

The Sofia Protocol target for reducing nitrogen oxide emissions is a little less successful as many of the countries that signed it are unlikely to meet the targets due to the large volume of traffic that hinders the success of the protocol.

National Emissions Ceilings Directive within the EU: The National Emission Ceilings Directive (NECD) was agreed in 2001. It sets emission ceilings to be achieved from 2010 onwards for sulphur dioxide, nitrogen oxides, non-methane volatile organic compounds and ammonia which cause harm to people’s health and to the natural environment as in the original Gothenburg Protocol. The UK has met all four of its emission ceilings by 2010 and continues to do so.

Conclusion

Despite the fact that acid pollution has decreased as most of the physical and legislative measures taken managed to deal with the problems and most developed countries have fallen sulphate emissions unlike developing countries. However nitrogen oxide levels in most cities around the world are increasing, owing to the huge volume of traffic emissions from vehicles. Moreover, acid rain is harmful to living organisms due to its toxicity and has dire consequences on the soil, forests, streams and lakes of a given ecosystem.