Pollution Archives

71. Thermal pollution which involves release of excessive amounts of heate

Thermal pollution which involves release of excessive amounts of heated water in aquatic systems is harmful. It is because hot water:

[amp_mcq option1=”kills aquatic plants.” option2=”causes oxygen starvation.” option3=”kills aquatic microbes.” option4=”causes CO₂ depletion.” correct=”option2″]

This question was previously asked in

UPSC Geoscientist – 2020

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The release of excessive heated water into aquatic systems causes thermal pollution, which is harmful because hot water holds less dissolved oxygen compared to cold water, leading to oxygen starvation for aquatic organisms.

– Solubility of gases in water decreases as temperature increases. Therefore, less oxygen can dissolve in hot water.
– Higher water temperatures increase the metabolic rates of fish and other aquatic organisms, which increases their demand for oxygen.
– The combined effect of reduced oxygen availability and increased oxygen demand can lead to stress, suffocation, and death of aquatic life.

– Thermal pollution can also affect the reproduction, growth, and behavior of aquatic species.
– It can alter species composition, favoring tolerant species and eliminating sensitive ones.
– Sources of thermal pollution often include cooling water discharges from power plants, industrial facilities, and urban runoff.

72. Which of the following particulate matters (size based) are notified p

Which of the following particulate matters (size based) are notified pollutants in National Ambient Air Quality Standards (NAAQS)?

[amp_mcq option1=”PM 10 and PM 3.5″ option2=”PM 9 and PM 2.5″ option3=”PM 10 and PM 2.5″ option4=”PM 5 and PM 3.5″ correct=”option3″]

This question was previously asked in

UPSC Geoscientist – 2020

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India’s National Ambient Air Quality Standards (NAAQS), as revised in 2009, include standards for particulate matter based on size, specifically PM 10 and PM 2.5.

– Particulate matter is a mixture of solid particles and liquid droplets found in the air.
– PM10 refers to particles with a diameter of 10 micrometers or less.
– PM2.5 refers to fine particles with a diameter of 2.5 micrometers or less.
– Both PM10 and PM2.5 are regulated under NAAQS due to their significant health impacts.

– The NAAQS specify concentration limits for PM10 and PM2.5 over different averaging periods (e.g., 24-hour and annual mean).
– Other pollutants listed in NAAQS include Sulphur Dioxide (SO₂), Nitrogen Dioxide (NO₂), Carbon Monoxide (CO), Ozone (O₃), Lead (Pb), Ammonia (NH₃), Benzene (C₆H₆), Benzo(a)Pyrene (BaP), Arsenic (As), and Nickel (Ni).

73. Fertilizers are used to obtain higher yields of crops. However, all nu

Fertilizers are used to obtain higher yields of crops. However, all nutrients are usually not available in fertilizers. Which one of the following nutrients is usually not available in fertilizers?

[amp_mcq option1=”Iron” option2=”Potassium” option3=”Nitrogen” option4=”Phosphorus” correct=”option1″]

This question was previously asked in

UPSC CDS-2 – 2021

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Fertilizers are primarily used to supply essential nutrients to plants, most commonly Nitrogen (N), Phosphorus (P), and Potassium (K), known as macronutrients. While plants also require micronutrients like Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Boron (B), Molybdenum (Mo), and Chlorine (Cl), standard or general-purpose fertilizers usually focus on NPK. Iron is a micronutrient and is not always available in all standard fertilizer formulations, though it may be included in specific micronutrient mixtures or specialized fertilizers.

Nitrogen, Phosphorus, and Potassium are the primary nutrients universally found in common fertilizers. Iron is a micronutrient whose availability varies depending on the fertilizer type and the specific needs of the soil and crop.

Macronutrients (N, P, K) are required by plants in larger quantities, while micronutrients (like Fe) are needed in smaller amounts. While important for plant health, the question asks which one is *usually not available* in fertilizers, implying it’s not a guaranteed component unlike N, P, or K in most standard products.

74. Which one of the following is not included in the National Air Quality

Which one of the following is not included in the National Air Quality Index?

[amp_mcq option1=”Sulphur” option2=”Nitrogen dioxide” option3=”Lead” option4=”Methane” correct=”option4″]

This question was previously asked in

UPSC CDS-2 – 2017

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Methane is not included in the pollutants measured for the National Air Quality Index (NAQI) in India.

The National Air Quality Index (NAQI) in India measures the levels of eight major air pollutants: Particulate Matter (PM₁₀ and PM₂.₅), Ozone (O₃), Sulphur Dioxide (SO₂), Nitrogen Dioxide (NO₂), Carbon Monoxide (CO), Ammonia (NH₃), and Lead (Pb).

Methane (CH₄) is a significant greenhouse gas contributing to climate change, but it is not one of the standard criteria pollutants monitored for reporting ambient air quality health impacts via the NAQI. Sulphur, Nitrogen dioxide, and Lead are represented by SO₂, NO₂, and Pb respectively, which are part of the NAQI pollutants.

75. Which of the following radioactive substances enters/enter the human b

Which of the following radioactive substances enters/enter the human body through food chain and causes/cause many physiological disorders?

[amp_mcq option1=”Strontium-90″ option2=”Iodine-131″ option3=”Cesium-137″ option4=”All of the above” correct=”option4″]

This question was previously asked in

UPSC CDS-2 – 2017

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Strontium-90, Iodine-131, and Cesium-137 are all radioactive isotopes that can enter the human body through contaminated food and water sources, becoming part of the food chain, and causing various physiological disorders.

These radioactive isotopes can accumulate in specific organs or tissues due to their chemical similarity to essential elements (Sr-90 to Calcium, I-131 to Iodine, Cs-137 to Potassium), leading to cellular damage and increased cancer risk.

These isotopes are common byproducts of nuclear fission, released during nuclear accidents (like Chernobyl or Fukushima) or nuclear weapons testing. Their presence in the environment poses long-term health risks through contamination of soil, water, plants, and animals, ultimately affecting humans via the food chain.

76. Blue Baby Syndrome is caused by the contamination of

Blue Baby Syndrome is caused by the contamination of

[amp_mcq option1=”nitrite (NO₂^–)” option2=”sulphite (SO₃^2-)” option3=”nitrate (NO₃^–)” option4=”sulphate (SO₄^2-)” correct=”option3″]

This question was previously asked in

UPSC CDS-2 – 2017

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The correct answer is nitrate (NO₃^–).

Blue Baby Syndrome, or methemoglobinemia, is primarily caused by the ingestion of water contaminated with high levels of nitrate. While nitrite (NO₂^–) is the substance that directly causes the conversion of hemoglobin to methemoglobin in the blood, the environmental contaminant commonly responsible, especially in drinking water from agricultural areas, is nitrate. Nitrate is converted to nitrite by bacteria in the digestive system, particularly in infants, leading to the syndrome.

Infants under six months are particularly susceptible because their digestive systems are more prone to converting nitrate to nitrite, and they have a less developed enzyme system to counteract methemoglobin formation. Sources of nitrate contamination in water often include fertilizer runoff, septic systems, and manure storage.

77. Which one of the following statements is not correct?

Which one of the following statements is not correct?

[amp_mcq option1=”Centre for Science and Environment in a recent study found that a number of commonly available brands of prepackaged breads tested positive for potassium bromate and potassium iodate.” option2=”Food Safety and Standards Authority of India recommended to the Health Ministry to remove potassium bromate from the list of permissible food additives.” option3=”The Union Government banned the use of potassium bromate as a food additive on the basis of the above recommendation.” option4=”Potassium bromate is a neurotoxin.” correct=”option4″]

This question was previously asked in

UPSC CDS-2 – 2016

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Statements A, B, and C accurately reflect events surrounding the controversy regarding potassium bromate in bread in India around 2016. The Centre for Science and Environment (CSE) did publish a study finding potassium bromate in bread. The Food Safety and Standards Authority of India (FSSAI) did recommend removing it from the list of permissible additives. The Union Government subsequently banned its use as a food additive. However, statement D is incorrect. While potassium bromate is considered harmful, it is primarily classified as a potential carcinogen (Group 2B by the International Agency for Research on Cancer – IARC), not a neurotoxin. There is no significant evidence classifying it primarily as a neurotoxin.

Potassium bromate was identified as a potential health hazard (specifically, a potential carcinogen) when used as a food additive, leading to its ban in India.

Potassium bromate was traditionally used as a flour improver, helping in dough development and giving a soft texture to bread. Due to its classification as a potential carcinogen and its ban in numerous countries, calls were made for its prohibition in India, which resulted in the FSSAI recommendation and subsequent government ban in 2016.

78. Excessive use of which of the following fertilizers may be responsible

Excessive use of which of the following fertilizers may be responsible for the presence of a toxic substance in groundwater?

[amp_mcq option1=”Nitrogen” option2=”Phosphate only” option3=”Potassium only” option4=”Phosphate and potassium” correct=”option1″]

This question was previously asked in

UPSC CDS-2 – 2016

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Excessive use of nitrogen fertilizers, particularly those containing nitrates or ammonium, can lead to the leaching of nitrates (NO₃⁻) into groundwater.

Nitrates are highly soluble and negatively charged, making them mobile in soil water and susceptible to leaching, especially in well-drained soils and areas with high rainfall or irrigation. Elevated levels of nitrates in drinking water are a human health concern, particularly for infants, as nitrates can be converted to nitrites in the digestive system, interfering with the blood’s oxygen-carrying capacity (causing methemoglobinemia). Phosphates are generally less mobile in soil due to adsorption to soil particles. Potassium is also relatively mobile but does not pose the same level of direct toxicity risk in drinking water as nitrates at common concentrations.

Nitrate contamination of groundwater is a significant environmental issue in agricultural regions worldwide. Other sources of nitrates include livestock manure and septic systems.

79. Which one of the following air pollutants combines with the haemoglobi

Which one of the following air pollutants combines with the haemoglobin of human blood and reduces its oxygen-carrying capacity, leading to suffocation and may cause even death?

[amp_mcq option1=”Chlorofluorocarbon” option2=”Fly ash” option3=”Carbon monoxide” option4=”Sulphur dioxide” correct=”option3″]

This question was previously asked in

UPSC CDS-2 – 2016

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Carbon monoxide (CO) is a toxic gas that readily binds to haemoglobin in red blood cells, forming carboxyhaemoglobin (COHb). This binding affinity is much higher than that of oxygen.

The formation of carboxyhaemoglobin reduces the amount of haemoglobin available to transport oxygen from the lungs to the body’s tissues. This leads to oxygen deprivation, causing symptoms like headache, dizziness, nausea, and in severe cases, suffocation and death. Other listed pollutants do not primarily affect oxygen transport in this manner. Chlorofluorocarbons (CFCs) damage the ozone layer. Fly ash is particulate matter from combustion. Sulphur dioxide (SO₂) is a respiratory irritant and contributor to acid rain.

Carbon monoxide is produced from the incomplete combustion of carbon-containing fuels (e.g., in vehicles, furnaces, stoves). Because it is odourless, colourless, and tasteless, it is often called the “silent killer”.

80. Which one of the following gases is released mostly from landfills in

Which one of the following gases is released mostly from landfills in urban areas?

[amp_mcq option1=”Nitrogen” option2=”Hydrogen” option3=”Methane” option4=”Oxygen” correct=”option3″]

This question was previously asked in

UPSC CDS-2 – 2016

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Methane is the gas released mostly from landfills in urban areas.

Landfills are significant sources of landfill gas, which is produced by the anaerobic decomposition of organic solid waste. The primary components of landfill gas are methane (CH4) and carbon dioxide (CO2). While CO2 is also released, methane is often present in high concentrations (typically 40-60%) and is a potent greenhouse gas.

Landfill gas collection systems are often installed in large landfills to capture methane for energy generation or flaring to reduce its release into the atmosphere. Other gases like nitrogen, oxygen, and hydrogen might be present in trace amounts, but methane and carbon dioxide constitute the bulk of the gas produced.