Shankar IAS Summary: Environmental Pollution- 3 | Shankar IAS for Environment: Summaries & MCQs - UPSC PDF Download

Chemistry of Acid Rain

Six fundamental steps contribute to the formation of acid rain:

1. The atmosphere receives sulfur and nitrogen oxides from both natural and man-made sources.
2. Some of these oxides precipitate directly to the ground as dry deposition, either near the source or at a distance.
3. Sunlight induces the formation of photooxidants, including ozone, in the atmosphere.
4. These photo-oxidants react with sulfur and nitrogen oxides, resulting in the production of H2SO4 and HNO3 through oxidation.
5. The sulfur and nitrogen oxides, photo-oxidants, and other gases (such as NH3) are involved in the process.
6. Acid rain, containing ions of sulfate, nitrate, ammonium, and hydrogen, falls as wet deposition.

Infertile Soil

Impact of Acid Rain

A. Soil

• Exchange between hydrogen ions and nutrient cations like potassium and magnesium causes the leaching of nutrients, leading to soil infertility.
• Decreased respiration of soil organisms is observed.
• An increase in ammonia due to decreased nutrients reduces the rate of decomposition.
• The nitrate level in the soil is found to decrease.
• Acid rain impact on soil is less in India due to predominantly alkaline soils with good buffering capacity.

B. Vegetation

• Acid rain affects trees and undergrowth, causing reduced or abnormal growth.
• Symptoms include discoloration and loss of foliar biomass, loss of feeder-root biomass (especially in conifers), premature aging of older needles in conifers, increased susceptibility to damage, death of herbaceous vegetation under affected trees, and prolific lichen production on affected trees.

C. Microorganisms

• pH influences the proliferation of microbial species, leading to a shift from bacteria-bound to fungi-bound microflora.
• This shift causes a delay in the decomposition of soil organic material and an increase in fungal diseases in aquatic life and forests.

D. Wildlife

• Effects on wildlife are not always evident but can impact productivity and survival.
• Direct effects include damage to eggs and tadpoles of breeding frogs and salamanders.
• Indirect effects involve the release of metals from soils into the aquatic environment, where they may be ingested by animals, leading to potential toxic effects.
• Other indirect effects include loss or alteration of food and habitat resources.

WildlifeE. Humans

• Acid rain affects human health in various ways.
• Obvious effects include bad smells, reduced visibility, and irritation of the skin, eyes, and respiratory tract.
• Direct effects encompass chronic bronchitis, pulmonary emphysema, and cancer.
• Indirect effects involve food poisoning through contaminated drinking water and food.
• Increased levels of toxic heavy metals like manganese, copper, cadmium, and aluminum contribute to adverse effects on human health.

F. Acid rain damage on Materials

G. Socio-economic Impacts of Acid Rain: The detrimental effects of acid rain on agriculture and fishing contribute to the degradation of key life quality indicators, including Gross National Product (GNP) and per capita income. This impact is particularly pronounced in predominantly agricultural and developing nations such as India.