Pollution Archives

21. Consider the following statements: 1. Agricultural soils release ni

Consider the following statements:

1. Agricultural soils release nitrogen oxides into environment.
2. Cattle release ammonia into environment.
3. Poultry industry releases reactive nitrogen compounds into environment.

Which of the statements given above is/are correct?

1 only

2 and 3 only

4 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2019

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The correct answer is D) 1, 2 and 3.

This question assesses the understanding of sources of atmospheric nitrogen compounds.
1. Agricultural soils release nitrogen oxides into environment: Correct. Nitrous oxide (N₂O), a significant greenhouse gas, is released from agricultural soils through microbial processes (nitrification and denitrification), especially when nitrogen fertilizers are used. Other nitrogen oxides (like NO and NO₂) can also be released, though N₂O is the most significant from soil.
2. Cattle release ammonia into environment: Correct. Livestock, particularly cattle, excrete significant amounts of nitrogen in urine and feces. This nitrogen is converted to ammonia (NH₃) through microbial processes in manure and released into the atmosphere.
3. Poultry industry releases reactive nitrogen compounds into environment: Correct. Similar to cattle, poultry operations generate large amounts of nitrogen-rich manure, which leads to the release of ammonia and other reactive nitrogen compounds into the atmosphere. Poultry litter management is a major source of atmospheric ammonia.

All three statements describe significant anthropogenic sources of nitrogen compounds that impact the environment, contributing to air pollution, acid rain, eutrophication, and climate change (in the case of N₂O). Therefore, all three statements are correct. The options provided seem to have a typo with “4 only”; assuming option D represents “1, 2 and 3”, that is the correct choice.

22. In India, the use of carbofuran, methyl parathion, phorate and triazop

In India, the use of carbofuran, methyl parathion, phorate and triazophos is viewed with apprehension. These chemicals are used as

pesticides in agriculture

preservatives in processed foods

fruit-ripening agents

moisturising agents in cosmetics

This question was previously asked in

UPSC IAS – 2019

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The correct answer is A) pesticides in agriculture.

Carbofuran, methyl parathion, phorate, and triazophos are all chemical compounds widely known and used as pesticides, particularly insecticides and acaricides, in agriculture to control various pests that damage crops. These chemicals belong to the organophosphate and carbamate classes of pesticides, known for their toxicity.

Due to their high toxicity to humans and non-target organisms, including pollinators and aquatic life, the use of these chemicals is viewed with apprehension and has been restricted or banned in many countries, including India, although illegal use may still occur. They are not used as preservatives in processed foods, common fruit-ripening agents (like ethylene), or moisturising agents in cosmetics. Their primary application is in agriculture for pest control.

23. Why is there a great concern about the ‘microbeads’ that are released

Why is there a great concern about the ‘microbeads’ that are released into environment?

They are considered harmful to marine ecosystems.

They are considered to cause skin cancer in children.

They are small enough to be absorbed by crop plants in irrigated fields.

They are often found to be used as food adulterants.

This question was previously asked in

UPSC IAS – 2019

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The correct answer is A) They are considered harmful to marine ecosystems.

Microbeads are tiny plastic particles, typically less than 5 mm in diameter, used in various products like cosmetics, toothpastes, and abrasive cleaners. When washed down drains, they enter wastewater systems but are often too small to be filtered out. They are then released into rivers, lakes, and oceans. Once in aquatic environments, microbeads persist for a very long time and pose a significant threat to marine life.

Aquatic organisms, from small zooplankton to fish and birds, can ingest microbeads, mistaking them for food. Ingested plastic can cause physical harm, block digestive tracts, and leach harmful chemicals. Microbeads also absorb pollutants from the surrounding water, concentrating toxins which can then be transferred up the food chain. This biomagnification of toxins is a major environmental concern. The widespread presence and persistence of microbeads in marine environments necessitate efforts to reduce their use and prevent their release. Concerns about skin cancer, absorption by crop plants, or use as food adulterants are not the primary reasons for concern about microbeads in the environment.

24. With reference to agricultural soils, consider the following statement

With reference to agricultural soils, consider the following statements :

A high content of organic matter in soil drastically reduces its water holding capacity.
Soil does not play any role in the sulphur cycle.
Irrigation over a period of time can contribute to the salinization of some agricultural lands.

Which of the statements given above is/are correct ?

1 and 2 only

3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2018

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The correct answer is B) 3 only.

Let’s evaluate each statement:
1. **A high content of organic matter in soil drastically reduces its water holding capacity:** This statement is incorrect. Organic matter is like a sponge; it significantly *increases* the soil’s ability to absorb and retain water. Soils with high organic matter content hold much more water than soils with low organic matter.
2. **Soil does not play any role in the sulphur cycle:** This statement is incorrect. Soil plays a vital role in the sulphur cycle. It is a major reservoir for sulphur, primarily in organic form. Microorganisms in the soil are essential for the transformation of sulphur compounds (e.g., decomposition of organic matter releasing sulphate, oxidation and reduction reactions of sulphur compounds). Plant uptake of sulphate from the soil is also a key part of the cycle.
3. **Irrigation over a period of time can contribute to the salinization of some agricultural lands:** This statement is correct. Irrigation water, especially in arid and semi-arid regions, contains dissolved salts. When water is applied to fields, plants use some water, and much of it evaporates from the soil surface. The dissolved salts, however, are left behind. Without adequate drainage, these salts accumulate in the topsoil over time, leading to salinization, which reduces soil fertility and plant growth.

Soil health is critical for sustainable agriculture and ecosystem function. Organic matter content not only improves water holding capacity but also enhances soil structure, aeration, nutrient availability, and supports beneficial microbial activity. Salinization is a major land degradation issue globally, often exacerbated by unsustainable irrigation practices and poor drainage.

25. Which of the following is/are the possible consequence/s of heavy sand

Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds ?
Consider the following statements:

Decreased salinity in the river
Pollution of groundwater
Lowering of the water-table

Select the correct answer using the code given below:

1 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2018

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The correct answer is B) 2 and 3 only.

Let’s evaluate each statement:
1. **Decreased salinity in the river:** Heavy sand mining typically impacts the physical structure of the riverbed and flow dynamics, and potentially groundwater interaction. It does not directly cause a decrease in salinity in the river water itself. In coastal areas, it might affect the balance between freshwater and saltwater, potentially leading to increased saltwater intrusion rather than decreased salinity in river areas influenced by tides. This statement is incorrect.
2. **Pollution of groundwater:** Sand and gravel in a riverbed act as a natural filter, helping to purify water as it infiltrates into the groundwater system. Heavy sand mining removes this protective layer, making the groundwater aquifer more vulnerable to contamination from surface pollutants (like agricultural runoff, industrial waste, sewage). This statement is correct.
3. **Lowering of the water-table:** Riverbeds are often hydraulically connected to the surrounding groundwater table. Removing large quantities of sand from the riverbed lowers the base level of the river and disrupts this connection. This can lead to a corresponding drop in the groundwater table in adjacent areas, affecting wells and vegetation that rely on shallow groundwater. This statement is correct.

Besides pollution of groundwater and lowering of the water table, heavy sand mining can also cause erosion of riverbanks, destabilize bridges and other infrastructure, degrade riparian habitat, and alter river morphology, impacting aquatic life. It can also lead to a coarsening of the riverbed sediment downstream.

26. Biological Oxygen Demand (BOD) is a standard criterion for

Biological Oxygen Demand (BOD) is a standard criterion for

Measuring oxygen levels in blood

Computing oxygen levels in forest ecosystems

Pollution assay in aquatic ecosystems

Assessing oxygen levels in high altitude regions

This question was previously asked in

UPSC IAS – 2017

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The correct answer is C) Pollution assay in aquatic ecosystems.

Biological Oxygen Demand (BOD) is a measure used to indicate the amount of dissolved oxygen consumed by microorganisms in a water sample while they decompose organic matter under aerobic conditions. It is a standard test for assessing the level of organic pollution in water bodies.

High BOD values indicate that there is a large amount of biodegradable organic material in the water, which consumes a significant amount of dissolved oxygen as it decomposes. This depletion of oxygen can harm aquatic life. Therefore, BOD is a crucial parameter in evaluating the quality of water and the extent of pollution in rivers, lakes, and other aquatic ecosystems. Options A, B, and D relate to oxygen levels in blood, forests, or high altitudes, which are not measured by BOD.

27. In the context of solving pollution problems, what is/are the advantag

In the context of solving pollution problems, what is/are the advantage/advantages of bioremediation technique?

1. It is a technique for cleaning up pollution by enhancing the same biodegradation process that occurs in nature.
2. Any contaminant with heavy metals such as cadmium and lead can be readily and completely treated by bioremediation using microorganisms.
3. Genetic engineering can be used to create microorganisms specifically designed for bioremediation.

Select the correct answer using the code given below:

1 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2017

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The correct answer is C, stating that statements 1 and 3 are correct.

Bioremediation is a waste management technique that uses organisms, primarily microorganisms, to neutralize pollutants in a contaminated site by degrading them into less toxic or non-toxic substances. Genetic engineering can enhance the capabilities of these microorganisms for specific bioremediation tasks.

Statement 1 accurately describes bioremediation as enhancing natural biodegradation processes to clean up pollution. Statement 3 is correct; genetic engineering can be employed to develop microorganisms with improved pollutant degradation efficiency or resistance to toxic environments, specifically designed for bioremediation applications (e.g., genetically engineered bacteria). Statement 2 is incorrect. While bioremediation is effective for many organic contaminants, heavy metals like cadmium and lead are elemental and cannot be degraded by microorganisms. Bioremediation techniques might be used to immobilize or transform them into less mobile forms (e.g., through biosorption or bioprecipitation), but they are not ‘readily and completely treated’ by degradation.

28. In the cities of our country, which among the following atmospheric ga

In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index?

1. Carbon dioxide
2. Carbon monoxide
3. Nitrogen dioxide
4. Sulfur dioxide
5. Methane

Select the correct answer using the code given below.

1, 2 and 3 only

2, 3 and 4 only

1, 4 and 5 only

1, 2, 3, 4 and 5

This question was previously asked in

UPSC IAS – 2016

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The Air Quality Index (AQI) in India measures 8 pollutants. The gases typically considered for AQI calculation in urban areas are: Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), and Ozone (O3). Ammonia (NH3) is also included. Particulate matter (PM10 and PM2.5) and Lead (Pb) are also measured.
From the given list:
1. Carbon dioxide (CO2): Not included in standard AQI as it is primarily a greenhouse gas, not an air pollutant causing direct, immediate health impacts at typical ambient concentrations, unlike the others.
2. Carbon monoxide (CO): Included.
3. Nitrogen dioxide (NO2): Included.
4. Sulfur dioxide (SO2): Included.
5. Methane (CH4): Not included in standard AQI; it is a greenhouse gas.
Therefore, CO, NO2, and SO2 are among the atmospheric gases normally considered in calculating the value of Air Quality Index in cities.

Standard urban AQI measures pollutants like CO, NO2, SO2, O3, PM2.5, PM10. CO2 and Methane are greenhouse gases not typically included in AQI.

The AQI is a tool for effective communication of air quality status to people in simple terms. It transforms complex air quality data into a single number and color, indicating health implications.

29. Why does the Government of India promote the use of ‘Neem-coated Urea’

Why does the Government of India promote the use of ‘Neem-coated Urea’ in agriculture?

Release of Neem oil in the soil increases nitrogen fixation by the soil microorganisms

Neem coating slows down the rate of dissolution of urea in the soil

Nitrous oxide, which is a greenhouse gas, is not at all released into atmosphere by crop fields

It is a combination of a weedicide and a fertilizer for particular crops

This question was previously asked in

UPSC IAS – 2016

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The primary reason the Government promotes Neem-coated Urea is that the coating slows down the release of nitrogen from the urea into the soil.

Neem coating acts as a nitrification inhibitor. It slows down the conversion of urea into ammonium nitrate and then into nitrates by soil bacteria. This process makes nitrogen available to plants over a longer period, reduces nitrogen loss through leaching and volatilization, and increases nitrogen use efficiency by crops.

– By slowing down nitrification, Neem-coated Urea also helps reduce the emission of nitrous oxide (N2O), a potent greenhouse gas produced during the nitrification and denitrification processes in soil. So, while it doesn’t *eliminate* N2O release entirely, it reduces it compared to uncoated urea.
– Increased nitrogen efficiency means farmers need less urea, saving costs and reducing environmental impact.
– Neem has certain pest repellent properties, which might offer minor benefits, but the main purpose of coating urea with neem oil is to control the rate of nitrogen release.

30. With reference to bio-toilets used by the Indian Railways, consider th

With reference to bio-toilets used by the Indian Railways, consider the following statements:

1. The decomposition of human waste in the bio-toilets is initiated by a fungal inoculum.
2. Ammonia and water vapour are the only end products in this decomposition which are released into the atmosphere.

Which of the statements given above is/are correct?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC IAS – 2015

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Both statements are incorrect.

Indian Railways’ bio-toilets use a bacterial inoculum, not fungal, for the anaerobic decomposition of human waste. The end products of this decomposition include biogas (primarily methane and carbon dioxide) and treated water, not solely ammonia and water vapour.

The anaerobic bacteria consortium (specifically, bacteria from the DRDO-developed inoculum) breaks down the complex organic matter in human waste. The biogas is released into the atmosphere (or sometimes vented), and the treated liquid effluent is disinfected and discharged. While some ammonia might be produced, it is not the only end product released along with water vapour.