Question

In the human-induced process called acid precipitation, the main biogeochemical cycles that are altered are the _____ cycles and one effect in lakes is to ______ population of nitrifying bacteria.

• A. Phosphorus and nitrogen, decrease
• B. Nitrogen and sulphur, decrease
• C. Nitrogen and sulphur increase
• D. Phosphorus and sulphur, decrease

Answer 1

Answer: (B)

Nitrogen and sulphur, decrease

Acid rain or acid precipitation is rainfall and other forms of precipitation with a pH of less than 5. Acid rain is caused by large scale emission of acidic gases into the atmosphere from thermal power plants, industries and automobiles. The common ones are sulphur dioxide, nitrogen oxides $\left({NO}_x\right)$, volatile organic carbons $\left({VOC}_s\right)$ and hydrogen chloride. Sulphur dioxide and nitrogen oxides are changed in the atmosphere into sulphuric acid and nitric acid by combining with oxygen and water. When such rain falls on land, it acidifies the soil and water. Nitrifying bacterial populations and thereby densities decrease in acid stressed water and soil.

So, the correct answer is 'Nitrogen and sulphur, decrease'.