• Nihira Prakash

Acid Rain

Acid rain is something we all must have heard of. It's a form of precipitation that has elevated levels of hydrogen ions or in simpler words, low pH. It's known to have adverse effects on plants, aquatic animals, and infrastructure.

Numerous efforts have been made right since the 1970s to decrease the release of the two main gases responsible for acid rain into the atmosphere by various governments and most of them have shown positive results as well. Acid rains lead to adverse impacts on forests, freshwaters bodies and soils. It leads to killing of insects and aquatic organisms, and also causes paint to peel. Corrosion of metal on structures like bridges is also a very common effect of acid rain. Moreover, acid rains impact human health too in a bad way.

The most important gas which leads to acidification is sulphur dioxide.Nitrogen oxides can also be produced naturally by lightning strikes, and sulphur dioxide is produced by volcanic eruptions. Emissions of nitrogen oxides that are later oxidized to form nitric acid should be taken into account as there are stricter controls over the emissions of sulfur compounds and less heed over nitrogen compounds. Stats suggest that 70 Tg per year in the form of SO2 comes from fossil fuel combustion and industry, 2.8 Tg from wildfires, and 7–8 Tg per year from volcanoes.

Facts say that fumaroles from the Laguna Caliente, which is a crater of Poás Volcano, is responsible for extremely high volume of acid rains and smog, with acidity as high as a pH of the value 2. Acid rain caused by these fumaroles clear out large areas of any sort of crops and vegetation and causes irritation to the eyes and lungs of the people settled nearby this area.

Moreover, gases that lead to acid rains are created not just in the atmosphere but through various biological processes we get to see on the land, in wetlands, and in the oceans. The major biological source of sulphur compounds is dimethyl sulphide.

Human activities like livestock rearing, factories and industries, motor vehicles and generation of electricity are the main causes of acid rain with loads of sulfur and nitrogen compounds. Electricity generation by the use of coal is one of the greatest contributors to the air pollution which is directly related and responsible for acid rains. The harmful gases that are released can spread over hundreds of kilometers in the atmosphere, making it worse on windy days, before they are converted into acids.

In industrialized areas, pH readings during rainfalls are as low as 2.4 in wells! Acid rain due to industries is a substantial problem in countries like China and Russia. Areas here all burn sulfur-containing fuels like coal to generate heat and electricity. A well known example of this effect is the acid rain which falls in Scandinavia.

This issue of acid rain isn't taken a lot into account as acids rain isn't an 'every second day' issue, but it soon might become one. The amount of these rains is not only increasing with population and industrial evolution, but is becoming more and more widespread. The usage of tall smokestacks, which we see often when we pass through industrial settlements, to reduce local pollution leads to the spread of harmful gases and therefore acid rain over a larger area by releasing gases into regional atmospheric circulation.