1. Stubble burning

• Stubble burning also called as parali burning, stubble burning is a method of removing paddy crop residues from the field to sow wheat.
• It is usually done in the last week of September to November.
• It is usually required in areas that use the combined harvesting method which leaves crop residue behind.
• It is practised by the farmers to prepare the land for the next cultivation.
• It is practised mainly in the Indo-Gangetic plains of Punjab, Haryana, and UP to clear the fields for rabi crop sowing.

Why stubble burning is practised?

• Limited duration- Multiple cropping and shortened intervals between crops give a very short window of about 10–15 days during which the field needs to be prepared for the next crop.
• There is only short time available between rice harvesting and sowing of wheat as delay in sowing wheat affects the wheat crop.
• Cheap- It is considered one of the cheapest methods to clean the field after the harvesting season.
• Labour shortage- Use of expensive labour for stubble extraction is not feasible, especially in Punjab and Haryana where farm sizes are large.
• Clears all stubble- The use of mechanized harvesters leaves stubble of 10– 30 cm in the field, depending on the type of crop, which was not the case earlier with manual harvesting.
• Low crop residue- The low commercial and economic value of crop residue, coupled with the high costs of processing, reduces its value for farmers.

Impacts of stubble burning

• Air pollution- It emits toxic pollutants in the atmosphere containing harmful gases like carbon monoxide (CO), methane (CH4), carcinogenic polycyclic aromatic hydrocarbons, volatile organic compounds (VOC).
• The combustion of agricultural residue is a prominent contributor to air pollution in certain regions of northern India.
• Soil fertility- Soil becomes less fertile and its nutrients are destroyed when the husk is burnt on the ground.
• Heat penetration- Stubble burning generates heat that penetrates into the soil, causing an increase in erosion, loss of useful microbes and moisture.
• Climate change- The release of toxic gases from stubble burning will increase global warming, further aggravating the climate change.
• Uncontrolled firing- Risk of fires spreading out of control, could turn into huge pit of flames.

Strategies to reduce stubble burning

• Promote agri-implements- Punjab has rolled out schemes for providing subsidy for mechanical implements that can mix the crop residue with soil to improve fertility.
• Promote co-ownership models for the agri-implements which can make such implements accessible to farmers.
• Foster awareness- Farmers should understand the value of crop residues and use of agri implements in extraction and packaging.
• Power generation- State governments need to incentivise establishment of biomass-based power plants through fiscal interventions and prioritization. Example- Biomass co-firing
• Promote R&D- Punjab Agricultural University is developing a variant of paddy straw that has lower silica content, thereby making it suitable for utilisation in biomass-based power plants.
• Biofuel production- The State governments, along with appropriate policy interventions from the Central government need to incentivise utilisation of biofuels.
• Industrial application- Biomass pellets can be sold commercially as the main fuel for industrial boilers and replace coal. Micro-pelletization should be incentivised and its local usage promoted.
• Crop residue collection mechanism- Create a uniform decentralised mechanism for the collection, storage and commercial sale of crop residue.

Chhattisgarh model

• A gauthan is a dedicated 5-acre plot, held in common by each village.
• Here, all the unused parali (paira in Chhattisgarhi) is collected through parali daan (people’s donations) and converted into organic fertiliser by rural youth.

2. GRAP

Graded Response Action Plan (GRAP) is a set of emergency measuresthat kick in to prevent further deterioration of air quality once it reaches a certain threshold in the Delhi-NCR region. It was approved by the Supreme Court in 2016 after the Supreme Court’s order in the matter of  C. Mehta vs. Union of India (2016)and notified in 2017.

• Implementation:
  • From 2021 onwards, the GRAP is being implemented by the
    • Till 2020, the Supreme Court-appointed Environment Pollution (Prevention & Control) Authority (EPCA)used to order States to implement GRAP measures.
  • The EPCA was dissolved and replaced by the Commission for Air Quality Management (CAQM)in 2020.
  • CAQM relies on air quality andmeteorological forecasts by the Indian Institute of Tropical Meteorology (IITM) and the India Meteorological Department (IMD).
• Revision:
  • Stage I (Poor Air Quality - AQI 201-300):Enforce NGT / Hon’ble SC’s order on over aged diesel / petrol vehicles.
  • Stage II (Very Poor- AQI 301-400):Targeted actions to combat air pollution at identified hotspots in the region. Regulated operations of DG (Diesel Generators) have been set across all sectors in the NCR.
  • Stage III (''Severe''- AQI 401-450):Impose strict restrictions on BS III petrol and BS IV diesel four-wheelers in certain areas and may suspend physical classes in schools for primary grade children up to Class 5.
  • Stage IV (Severe Plus- AQI greater than 450):When the AQI exceeds 450, four-wheelers registered outside Delhi, except for electric vehicles, CNG vehicles, and BS-VI diesel vehicles and vehicle carrying essential commodity, will not be allowed to enter the city.

Note: An AQI is a number used by government agencies to measure the air pollution levels and communicate it to the population. As the AQI increases, it means that a large percentage of the population will experience severe adverse health effects.

Initiatives to Combat Air Pollution

• Graded Response Action Plan (Delhi)
• Polluter Pay principle
• Smog Tower
• Tallest Air Purifier
• National Clean Air Programme (NCAP)
• BS-VI vehicles
• New Commission for Air Quality Management
• Turbo Happy Seeder (THS)
• Air Quality and Weather Forecasting and Research (SAFAR)
• Dashboard for Monitoring Air Quality
• National Air Quality Index (AQI)
• Air (Prevention and Control of Pollution) Act, 1981
• Pradhan Mantri Ujjwala Yojana (PMUY)

3. CRYPTOBIOSIS

Cryptobiosis is the condition of inactive metabolic activity during adverse environmental conditions. In this state, the organism can live for a longer period until the conditions are favourable again. Reproduction, development and repair stop due to the inactivation of the metabolic activities.

Cryptobiotic desiccation is the most common. For eg; nematodes, brine shrimp, yeast, tardigrades, etc. It explains the two potential states of life. Many organisms cannot exhibit this phenomenon because freezing or drying disrupts their membranes, which allows the leakage of small molecules or denatures the proteins.

Types of Cryptobiosis

Anhydrobiosis

Anhydrobiosis means “life without water”. It refers to the ability of some organisms to survive extreme water stress. This has been observed in lichens, cyanobacteria, yeast, mosses, algae, etc. This state is induced by desiccation.

Anoxybiosis

This situation occurs during lack of oxygen when the organism becomes turgid by taking in water and immobilising.

Chemobiosis

It is the suspension of metabolic activities in response to high levels of metabolic toxins. Tardigrades exhibit chemobiosis.

Cryobiosis

This type of cryptobiosis occurs during reduced temperatures. When the water surrounding the organism freezes, cryobiosis is initiated and all the metabolic activities of the organisms are paused.

Osmobiosis

It occurs in response to increased solute concentration of the solution in which the organism lives. However, less is known about this type.

Examples Of Animals Exhibiting Cryptobiosis

Brine shrimp

These are crustaceans that are found in salty lakes all over the world. They produce cysts known as “dormant eggs”, during unfavourable conditions. The cyst is metabolically inactive and can survive in dry and anaerobic conditions. These can survive boiling temperatures and temperatures below freezing point.

Yeast

The active dry yeast is commonly used in baking as a leaving agent. The live yeast is encapsulated in a thick, dry jacket of dead cells with some growth medium. Yeast can be stored at room temperature, or in the refrigerator or freezer for a very long time.

Tardigrades

These are microscopic organisms found in water. A matured tardigrade is 0.5 mm long with eight legs. They have the ability to suspend their metabolism and undergo cryptobiosis for almost 10 years. Due to this nature, they are able to survive extreme temperatures, pressure, desiccation, and radiation.

Bacteria

During environmental stress, the bacteria form dormant, tough, non-reproductive structures known as endospores. They help the bacteria to survive when the conditions are not favourable for survival. They are resistant to radiation, drying, temperature, chemical disinfectants, and starvation.

Cryptobiosis in Humans

Cryptobiosis in humans is known as suspended animation. Researchers have devised ways to save lives through cryptobiosis. Doctors in the US have been working on a technique known as Emergency Preservation and Resuscitation. In this, the blood in the body is replaced with cold saline fluid, which would decrease the body temperature to 10°C.  This chills the body and the brain and there is very less requirement for oxygen by the body. This reduces the chances of brain damage. By doing this they can get ample time to cure severe injuries such as those caused by accidents and gunshots. Soon after the treatment, the saline is replaced with blood and the body rewarms gradually. The process has successfully experimented on pigs.

PYQs

1] Consider the following: [2022]

1. Carbon monoxide
2. Nitrogen oxide
3. Ozone
4. Sulphur dioxide
Excess of which of the above in the environment is/are the cause(s) of acid rain?

a) 1, 2 and 3
b) 2 and 4 only
c) 4 only
d) 1, 3 and 4

Explanation

Acid rain is a term that refers to a mixture of wet and dry deposition from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The primary causes of acid rain are emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx), which react with the water molecules in the atmosphere to produce acids.

Carbon monoxide (CO) is a colorless, odorless, and toxic gas, but it does not contribute to acid rain. It is primarily a concern because it can be harmful to human health, particularly in enclosed spaces.

Nitrogen oxides (NOx), including nitrogen dioxide (NO₂) and nitric oxide (NO), are significant contributors to acid rain. They react with water, oxygen, and other chemicals in the atmosphere to form nitric acid, which can then fall to the ground in precipitation, contributing to the acidification of ecosystems.

Ozone (O₃) is a molecule composed of three oxygen atoms. It is not a direct contributor to acid rain. Ozone at ground level is a harmful air pollutant and a key component of smog, but it does not form acidic compounds that lead to acid rain.

Sulfur dioxide (SO₂) is a gas that is produced by volcanic eruptions and industrial processes, particularly the combustion of coal and oil at power plants and the smelting of mineral ores that contain sulfur. In the atmosphere, SO₂ can oxidize to form sulfuric acid (H₂SO₄), which is a major component of acid rain. The largest source of SO₂ in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. Smaller sources of SO₂ emissions include: industrial processes such as extracting metal from ore; natural sources such as volcanoes; and locomotives, ships and other vehicles and heavy equipment that burn fuel with a high sulfur content.    

Therefore, the correct answer is “2 and 4 only” because nitrogen oxides and sulfur dioxide are the pollutants that contribute to acid rain, while carbon monoxide and ozone do not.

2] In the context of WHO Air Quality Guidelines, consider the following statements: [2022]

1. The 24-hour mean of PM 2.5 should not exceed 15 pig/m3 and annual mean of PM2.5 should not exceed 5µg/m3.
2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather.
3. PM 10 can penetrate the lung barrier and enter the bloodstream.
4. Excessive ozone in the air can trigger asthma.
Which of the statements given above are correct?

a) 1, 3 and 4
b) 1 and 4 only
c) 2, 3 and 4
d) 1 and 2 only

Explanation

The World Health Organization (WHO) provides guidelines for air quality that set recommended limits for the concentration of pollutants in the air. These guidelines are designed to protect human health from the adverse effects of air pollution.

1. The 24-hour mean of PM2.5 should not exceed 15 µg/m³ and annual mean of PM2.5 should not exceed 5 µg/m³.
This statement is incorrect according to the latest WHO Air Quality Guidelines (2021). The WHO recommends that the 24-hour mean of PM2.5 should not exceed 15 µg/m³, but the annual mean should not exceed 5 µg/m³.

2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather.
This statement is incorrect. Ozone pollution tends to be higher during sunny periods with high temperatures and stagnant air conditions. Inclement weather, which often involves rain and wind, can help disperse pollutants and reduce ozone levels.

3. PM10 can penetrate the lung barrier and enter the bloodstream.
This statement is partially correct. While PM10 (particulate matter with a diameter of 10 micrometers or less) can penetrate deep into the lungs, it is the smaller PM2.5 particles that are more likely to penetrate the lung barrier and enter the bloodstream.

4. Excessive ozone in the air can trigger asthma.
This statement is correct. Ozone is a powerful respiratory irritant, and high levels of ozone can trigger asthma attacks and exacerbate other respiratory conditions.

Based on the analysis above, the correct statements are 1 (with the corrected values for PM2.5) and 4. Therefore, the correct answer is “1 and 4 only” if we correct the values in statement 1 to align with the WHO guidelines.

3] Consider the following statements: [2020]

1. Coal ash contains arsenic, lead and mercury.
2. Coal-fired power plants release sulphur dioxide and oxides of nitrogen into the environment.
3. High ash content is observed in Indian coal.
Which of the statements given above is/are correct?

a) 1 only
b) 2 and 3 only
c) 3 only
d) 1, 2 and 3

Explanation

Coal ash, the residue left after coal is burned, contains a variety of heavy metals, including arsenic, lead, and mercury. These substances are harmful to human health and the environment. If not properly managed, they can contaminate water sources and soil.

When coal is burned in power plants, it releases various pollutants into the atmosphere. Among these pollutants are sulfur dioxide (SO₂) and nitrogen oxides (NOx). SO₂ contributes to acid rain and respiratory problems, while NOx plays a significant role in the formation of ground-level ozone and smog, also contributing to respiratory issues.

Indian coal is known for its high ash content, often ranging from 30% to 45%. This ash content is significantly higher than that found in coal from many other parts of the world. The high ash content poses challenges for combustion and pollution control in power plants. It also requires more sophisticated handling and disposal methods to manage the large volumes of ash produced.

4] Consider the following statements: [2019]

The Environment Protection Act, 1986 empowers the Government of India to
1. State the requirement of public participation in the process of environmental protection, and the procedure and manner in which it is sought
2. Lay down the standards for emission or discharge of environmental pollutants from various sources
Which of the statements given above is/are correct?

a) 1 only
b) 2 only
c) Both 1 and 2
d) Neither 1 nor 2

Explanation

The Environment Protection Act, 1986 is an important legislation enacted by the Government of India to protect and improve the environment. It empowers the central government to take necessary measures to protect and improve the environment and to prevent and control environmental pollution.

The Act empowers the government to state the requirement of public participation in the process of environmental protection and the procedure and manner in which it is sought. This means that the central government can involve the public in the decision-making process related to environmental protection. This is important because it ensures that the public's concerns and opinions are taken into account while making decisions related to the environment.

The Act also lays down the standards for emission or discharge of environmental pollutants from various sources. This means that the central government can set limits on the amount of pollutants that can be emitted or discharged by industries, vehicles, and other sources. This is important because it helps to control the amount of pollution in the environment and protect the health of people and wildlife.

In conclusion, both the statements given in the question are correct. The Environment Protection Act, 1986 empowers the Government of India to state the requirement of public participation in the process of environmental protection and the procedure and manner in which it is sought. It also lays down the standards for emission or discharge of environmental pollutants from various sources.

5] In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of the Air Quality Index? [2016]

1. Carbon dioxide
2. Carbon monoxide
3. Nitrogen dioxide
4. Sulphur dioxide
5. Methane
Select the correct answer using the code given below.

a) 1, 2 and 3 only
b) 2, 3 and 4 only
c) 1, 4 and 5 only
d) 1, 2, 3, 4 and 5

Explanation

• The Air Quality Index is acquired by measuring emissions of eight major pollutants present in the air: Particulate matter (PM2.5 and PM10), Ozone (O3), Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Lead (Pb) and Ammonia (NH3) emissions.
• Readings are noted every hour. Each country has their air quality indexes based on its air quality standards.
• The government agencies are responsible for communicating to the public about the health hazards and how to keep a check on them.
• Under the Swachh Bharat Abhiyan, the National Air Quality Index was launched in September 2014 in New Delhi to measure India’s air quality index.
  • National Air Quality Index: Launched in 2014 with outline ‘One Number – One Color -One Description’ for the common man to judge the air quality within his vicinity.
• The Central Pollution Control Board (CPCB) has formed an expert group of medical professionals, air quality experts, academia, advocacy groups, and SPCBs. Also, a technical study was awarded to IIT Kanpur.
  • In 2014, the IIT Kanpur and the expert group recommended an AQI scheme for India.
• Six cities of India- New Delhi, Kolkata, Mumbai, Pune, and Ahmedabad have a continuous monitoring system that records data in real-time.
• There are six categories of AQI:
  • Good (0-50)
  • Satisfactory (50-100)
  • Moderately polluted (100-200)
  • Poor (200-300)
  • Very Poor (300-400)
  • Severe (400-500)
• The colour-coded AQI index was launched in India in 2014, and it helps the public and the government understand the condition of the air and what subsequent measures are to be taken to combat the situation, based on its severity.

Therefore, the correct answer is “2, 3 and 4 only”.

6] With reference to ‘fly ash’ produced by the power plants using the coal as fuel, which of the following statements is/are correct? [2015]

1. Fly ash can be used in the production of bricks for building construction
2. Fly ash can be used as a replacement for some of the Portland cement contents of concrete
3. Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic elements.
Select the correct answer using the code given below

a) 1 and 2
b) 2 only
c) 1 and 3
d) 3 only

Explanation

Fly ash is a byproduct of burning coal in power plants. It is a fine, powdery substance that is carried away by the flue gases and collected by electrostatic precipitators or bag filters. Fly ash has several uses, some of which are discussed below. 

Fly ash can be used as a raw material in the production of bricks for building construction. The addition of fly ash in brick making can improve the quality of bricks by reducing their permeability, increasing their strength, and enhancing their durability. Fly ash bricks are also cheaper than traditional clay bricks.

Fly ash can be used as a partial replacement for Portland cement in the production of concrete. Portland cement is the primary binding agent in concrete, but it has a high carbon footprint as it requires a lot of energy to produce. By replacing a portion of Portland cement with fly ash, the carbon footprint of concrete can be reduced. Fly ash also improves the workability and durability of concrete. 

Fly ash is composed of various elements, including silicon dioxide, calcium oxide, aluminum oxide, iron oxide, magnesium oxide, and sulfur trioxide. The exact composition of fly ash varies depending on the type of coal burned and the conditions of the combustion process. While fly ash does contain trace amounts of some heavy metals, such as arsenic, cadmium, and lead, they are present at levels that are lower than those considered harmful to human health and the environment.

In conclusion, fly ash is a versatile material that has several uses, including brick production and as a partial replacement for Portland cement in concrete. Fly ash is composed of various elements, including silicon dioxide and calcium oxide, and while it does contain trace amounts of some heavy metals, they are present at levels that are not harmful.
Therefore, the correct answer is “1 and 2”.

7] Lead, ingested or inhaled, is a health hazard. After the addition of lead to petrol has been banned, what still are the sources of lead poisoning? [2012]

1. Smelting units
2. Pens and pencils
3. Paints
4. Hair oils and cosmetics

Select the correct answer using the codes given below:
a) 1,2 & 3 only                       b) 1 and 3 only
c) 2 & 4 only                          d) 1,2,3 & 4

Explanation

Lead, when ingested or inhaled, is a health hazard. Although the addition of lead to petrol has been banned, there are still sources of lead poisoning. These sources include:

1. Smelting Units Smelting units, where metals like lead and zinc are extracted from ores, are a significant source of lead pollution. The fumes and dust generated during the smelting process contain high levels of lead, which can lead to lead poisoning in nearby communities.

2. Paints Lead was commonly used as a pigment in paints, especially in older buildings. When these buildings are renovated or demolished, lead particles can become airborne and pose a risk of lead poisoning.

3. Pens and Pencils Some older pens and pencils may contain lead in their ink or graphite. When children chew on the ends of these writing instruments, they may inadvertently ingest lead.

4. Hair Oils and Cosmetics Some traditional hair oils and cosmetics, particularly those imported from other countries, may contain high levels of lead. When these products are applied to the skin, lead can be absorbed into the body.
Therefore, the correct answer is “1 and 3”.

8] Consider the following: [2011]

1. Carbon dioxide.
2. Oxides of nitrogen.
3. Oxides of Sulphur

Which of the above is/are the emission/emissions from coal combustion at thermal power plants?
a) 1 only                                   b) 2 and  3 only
c) 1 and 3 only                         d) 1, 2, and 3

Explanation

The main emissions from coal combustion at thermal power plants are Carbon dioxide (CO₂), Nitrogen oxides (NOx), Sulfur oxides (SOx), Chlorofluorocarbons (CFCs), carbonaceous material (soot), and air-borne inorganic particles such as fly ash, also known as suspended particulate matter (SPM) and other trace gas species. Carbon dioxide, nitrous oxide, and chlorofluorocarbons are greenhouse gases. Evidence accumulated by the Inter-governmental Panel on Climate Change (IPCC) suggests that emissions of these greenhouse gases might be responsible for climate change, a global concern.