Pollution: UPSC Previous Year Questions (Environment and Ecology)

Explanation

Water Pollution is the contamination of water bodies, usually as a result of human activities. Heavy metal water pollution is the contamination of water with toxic heavy metals, such as lead, mercury, cadmium, arsenic, and chromium etc. Heavy metals can enter the water through natural processes and human activities. Options 1, 3 and 5 are correct: Arsenic, Fluoride, Iron, Uranium, Nitrate, are some major groundwater pollutants in India.

Option 2 is incorrect: Sorbitol is a sugar alcohol found in fruits and plants with diuretic, laxative and cathartic properties. It is not related with drinking water pollution.

Option 4 is incorrect: Formaldehyde is used to preserve fish longer. The use of this chemical is banned in fresh foods by the Food Safety and Standards Authority of India. The International Agency for Research on Cancer (IARC) of WHO classifies formaldehyde as "carcinogenic to humans". Formaldehyde is not established as a drinking water pollutant.

Explanation

E-waste is any electrical or electronic equipment that’s been discarded. Recently, India’s first e-waste clinic was inaugurated in Bhopal. E-waste Sources Constituents PCBs, glass panels, and Computer monitors Lead Resistors & Semiconductors Cadmium Relays and switches, &PCBs Mercury Galvanised steel plates & decorator or hardener Chromium Cabling, Computer & housing Plastics & PVC Electronic equipments & circuit boards Brominated flame-retardants Front panels of CRTs Barium, Phosphorus & Heavy metals Copper wires, PCB tracks Copper Nickel Cadmium batteries Nickel Lithium-ion battery Lithium Motherboards Beryllium Options 1, 2, 3, 5 and 6 are correct: All elements in these options are the harmful constituents that are released into the environment due to improper disposal of e-waste.

Option 4 is incorrect: Heptachlor is a pesticide classified under Persistent Organic Pollutants (POPs) per the Stockholm Convention. It is unrelated to e-waste.

Option 7 is incorrect: Plutonium, while used in some industrial and military applications, is a radioactive material and is not classified as part of e-waste.

Explanation

Normal rain has a pH of about 5.6 when pH falls below this; it is called Acid rain (pH 4.2 to 4.4). Acid rain results when Sulphur Dioxide (SO₂) & Nitrogen Oxides (NOX) react with water, oxygen & other chemicals to form Sulfuric & Nitric acids. NOx + SO₂ + Moisture + other chemicals Acid Rain (HNO₃ + H₂ SO₄) Acid rain harms microorganisms in the soil; inhibits the activity of nitrogen fixation bacteria; soil acidification; ocean acidification; affects the growth of plants; food chain; kills aquatic animals; corrosion of metals and weathering of stone buildings & statues.

Explanation

Photochemical smog, often referred to as "Los Angeles smog," is most commonly found in urban areas with high numbers of automobiles. It does not require smoke or fog to form. This type of smog is formed from the nitrogen oxides and hydrocarbon (peroxyacetyl nitrate, a hazardous pollutant) vapors released by vehicles and other sources, which then undergo photochemical reactions in the lower atmosphere in the presence of sunlight.

Explanation

Aflatoxins are produced by certain species of fungi (moulds), specifically Aspergillus flavus and Aspergillus parasiticus, which often grow on stored grains and oilseeds under conditions of high humidity and temperature. Exposure to aflatoxins can lead to serious health issues, including liver cancer, especially in children. Beyond health risks, aflatoxins cause significant economic losses, with an estimated 25% of global food crops affected annually.