Wednesday, October 9, 2013

Acid Rain Impacts

Location of acid rain and trends
Urban air pollution is probably the most well-known problem created by rapid industrialization. Air pollution around major factories, thermal power plants, open mines and quarries has attracted a lot of attention. Rain over India is much less acidic than most of the other countries in Asia, Europe and North America. However, it has become more and more acidic over the last few decades.

The pH of rain in India ranges from 5.9 to 8.4, and the average is about 6.7. India seems to be much better off than the USA (4.15–6.19), Canada (4.23–5.96), Germany (4.05–4.25), Norway (4.10–4.40), and most other countries. However, there are places in India where things are not so good. Parts of south Bihar and West Bengal are likely to be the worst affected, along with the southernmost tip of the Indian peninsula. Occasional rains with a pH of 4.8 have been reported from Chembur in Mumbai and a pH of 4.5 from Delhi. The more worrying trend is the gradual acidification of the rain in India over the last couple of decades – the pH has decreased from 7.0 to 6.1 in Delhi, and from 9.1 to 6.3 in Agra.

Causes and impacts
Thermal power plants in India, which generally use coal with relatively high sulphur content (0.5 per cent to three per cent), are the major source of oxides of sulphur – they release about 2,500 tons per year. Oxides of nitrogen are produced during high-temperature combustion. The greatest source of nitrogen oxides is road vehicles.

India has been rather lucky to have predominantly alkaline-rich soils. For example, in the Thar Desert in the northwest of India, the aerosols from coastal areas help reduce the acidity to a considerable extent. Higher temperatures prevalent in India also contribute towards transforming the oxides of sulphur to sulphates and oxides of nitrogen to nitrates. India also does not have natural sources of sulphur emission like volcanoes. These factors have kept the acid rain in check so far. However, the emissions from the increasing number of power plants, industries, fossil-fuel burning and vehicles have gradually begun to overcome the natural checks. In 1990, none of the ecosystems in India was threatened by acid rain. However, if steps are not taken to control emissions, by the year 2020 about 85 per cent of the ecosystems will be threatened by acid rain.

Possible solutions
India’s solutions are similar to that of many other countries: the use of cleaner fuels, a gradual switching to renewable energy and the use of catalytic converters. In addition, a 66–130 million-hectare wasteland should provide enough ground for growing biomass and using renewable sources of energy in a sustainable manner.

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