A study by Indian Institute of Tropical Meteorology and India Meteorological Department revealed that in many parts of the country the ratio of harmful acid is increasing day by day in the” life-giving” rainfall, particularly in the last 10 years. Research of rainwater samples from different places of the country, such as Nagpur, Visakhapatnam, Allahabad, Mohanbari (Assam) and Kodaikanal in the year 2001-2012 showed an intervening level of water, which is water’s pH level is extended from 4.77 to 5.32.
Normal rainwater has a pH of about 5.6, is slightly acidic because CO2 (carbon dioxide) dissolves into it forming weak carbonic acid. So rainwater with pH level below 5.65 is considered acidic; hence these busy places have been getting `acid rain’ and polluting the country.
Acidity and alkalinity solution are measured using a pH scale (Potential of hydrogen, or pH), for where the pH or potential of Hydrogen level of pure water is 7.0, which sum is neutral. But in normal water with a pH level lower than 7 is considered acidic. The higher a substance’s pH (greater than 7), the more alkaline it is and the lower a substance’s pH (less than 7), the more acidic it is.
Acid rain results when polluting gases such as oxides of nitrogen and sulphur [sulphur dioxide (SO2) and nitrogen oxides (NOX)] are emitted from power plants, automobiles, manufacturing, oil refineries and other industries and mixing into the atmosphere and transported by wind and air currents. The nitrogen oxides (NOX) and sulphur dioxide (SO2) react with water, oxygen and other chemicals to form nitric and sulphuric acids. These then mix with water and other materials before falling to the ground as Acid rain water.
Acid rain is not only responsible to reduce soil nutrition (dissolve salts of heavy metals found in rocks and soil and other natural surfaces) but also corrosive to monuments, steel structures and stone buildings. Acid rain has been shown to have adverse impacts on insect and aquatic life-forms also and ultimately, human, animal and plant physiologies. “Acid rain causes leaching of soil nutrients, which means that these nutrients are not available to plants and crops grown in the soil, affecting crop nutrition and productivity. Among other harmful effects, acid rain has had a corrosive effect on monuments in the country, like the case of the Taj Mahal,” scientists who were linked with the study said. It does not directly affect the human health but by mixing of acid in rainwater may give some diseases of heart and lungs like asthma and bronchitis.
The research led by two scientists V Vizaya Bhaskar and P S P Rao, which was published in the Journal of Atmospheric Chemistry (Springer). According to the study, almost all Global Atmosphere Watch (GAW) stations in the country showed a decreasing trend in pH levels with each passing decade during the period of analysis (1981 to 2012).
The scientists analysed samples of collected acid rain from 10 GAW stations in India (Mohanbari, Srinagar, Jodhpur, Nagpur, Pune, Vishakhapatnam, Port Blair, Allahabad, Kodaikanal (Tamil Nadu) and Minicoy in Lakshadweep – spread across the length and breadth of the country.