Read the passage and answer the questions:
WATER POLLUTION
Indiscriminate use of water by increasing population and industrial expansion has led degradation of the quality of water considerably. Surface water available from rivers, canals, lakes, etc. is never pure. It contains small quantities of suspended particles, organic and inorganic substances. When concentration of these substances increases, the water becomes polluted, and hence becomes unfit for use. In such a situation, the self-purifying capacity of water is unable to purify the water. Though water pollutants are also created from natural sources (erosion, landslides, decay and decomposition of plants and animals, etc.) pollutants from human activities are the real causes of concern. Human beings pollute the water through industrial, agricultural and cultural activities. Among these activities, industry is the most significant contributor.
Industries produce several undesirable products including industrial wastes, polluted waste water, poisonous gases, chemical residuals, numerous heavy metals, dust, smoke, etc. Most of the industrial wastes are disposed off in running water or lakes. Consequently, poisonous elements reach the reservoirs, rivers and other water bodies, which destroy the bio-system of these waters. Major water polluting industries are leather, pulp and paper, textiles and chemicals.
Various types of chemicals used in modern agriculture such as inorganic fertilisers, pesticides and herbicides are also pollution generating components. These chemicals are washed down to rivers, lakes and tanks. These chemicals also infiltrate the soil to reach the ground water. Fertiliser induces an increase in the nitrate content of surface waters. Cultural activities such as pilgrimage, religious fairs, tourism, etc. also cause water pollution. In India, almost all surface water sources are contaminated and unfit for human consumption.
Water pollution is a source of various water-borne diseases. The diseases commonly caused due to contaminated water are diarrhoea, intestinal worms, hepatitis, etc. The World Health Organization shows that about one-fourth of the communicable diseases in India are water-borne.
Which of the following is mainly responsible for the increase in nitrate content of the surface water?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Fertiliser
Option (1) Landslides — Incorrect. Landslides are a natural source that adds soil and rock, not the chemicals of farming.
Option (2) Fertiliser — Correct. Modern agriculture spreads inorganic fertilisers on the fields. Rain and irrigation water wash these chemicals down into rivers, lakes and tanks, and once there, the fertiliser induces an increase in the nitrate content of surface waters.
Option (3) Tourism — Incorrect. Tourism is a cultural activity; the passage ties nitrate to fertiliser.
Option (4) Cultural Fairs — Incorrect. Fairs too are cultural activities; the nitrate comes from fertiliser.
NCERT (2025-26): “Water Pollution … Various types of chemicals used in modern agriculture such as inorganic fertilisers, pesticides and herbicides are also pollution generating components. These chemicals are washed down to rivers, lakes and tanks. These chemicals also infiltrate the soil to reach the ground water. Fertiliser induces an increase in the nitrate content of surface waters. Cultural activities such as pilgrimage, religious fairs, tourism, etc. also cause water pollution.…” |