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Question 35

Consider the following:
1. Carbon monoxide
2. Methane
3. Ozone
4. Sulphur dioxide
Which of the above are released into atmosphere due to the burning of crop/biomass residue?

AOptions

A) 1 and 2 only

B) 2, 3 and 4 only

C) 1 and 4 only

D) 1, 2, 3 and 4

BSolution

The burning of crop residue (stubble burning) and other forms of biomass is a major source of air pollution. Incomplete combustion of organic matter releases a complex mixture of gases and particulate matter into the atmosphere. All the listed substances are indeed released:

1. Carbon monoxide (CO): This is a product of incomplete combustion and is a highly toxic gas.

2. Methane (CH4): Another product of incomplete combustion and a potent greenhouse gas, released when biomass burns without sufficient oxygen.

3. Ozone (O3): While ozone itself is not directly emitted, its precursors, such as volatile organic compounds (VOCs) and nitrogen oxides (NOx), are released during biomass burning. These precursors then react in the presence of sunlight to form ground-level ozone, which is a harmful air pollutant.

4. Sulphur dioxide (SO2): Although biomass typically has lower sulfur content compared to fossil fuels, some amount of SO2 is still released during its combustion, depending on the specific composition of the biomass residue.

In addition to these, particulate matter (PM2.5, PM10), carbon dioxide (CO2), and other harmful compounds are also released during crop/biomass residue burning.

CStrategy

For questions on sources of pollution, consider the basic chemistry of combustion. Incomplete combustion of organic matter generally leads to the release of a variety of pollutants, including carbon monoxide, methane, and precursors for secondary pollutants like ozone. Be broad in your consideration of potential emissions.

DSyllabus Analysis

This question falls under the Environment & Ecology section of the UPSC Prelims syllabus, specifically related to air pollution and its sources, particularly from agricultural practices.

EQuestion Analysis

Easy to Medium. The impact of stubble burning is a well-publicized environmental issue, and the primary pollutants released are generally known.