All questions of Ocean Acidification for UPSC CSE Exam

The correct answer is option 'A' - Statement 1 only.

Explanation:
1. CFCs molecules are made up of calcium, fluorine, and carbon. - Incorrect
CFCs (chlorofluorocarbons) are not made up of calcium. They are compounds composed of carbon, fluorine, and chlorine atoms. The most common CFCs contain chlorine and fluorine, such as CFC-11 (trichlorofluoromethane) and CFC-12 (dichlorodifluoromethane).

2. Unlike other chemicals, CFCs cannot be eliminated from the atmosphere by the usual scavenging processes like photodissociation, rain-out, and oxidation. - Correct
This statement is true. CFCs are known for their stability and resistance to degradation in the atmosphere. They are non-reactive and do not undergo photodissociation or oxidation easily. This means that once released into the atmosphere, CFCs can persist for a long time and can be transported to the upper atmosphere where they can cause damage to the ozone layer.

CFCs were widely used in various applications such as refrigeration, air conditioning, aerosol propellants, and foam blowing agents. However, it was later discovered that CFCs are major contributors to ozone depletion. When CFCs are released into the atmosphere, they can reach the stratosphere where they can be broken down by ultraviolet (UV) radiation from the sun. The breakdown of CFCs releases chlorine atoms, which can then catalytically destroy ozone molecules.

Due to the detrimental effects of CFCs on the ozone layer, the production and use of most CFCs have been phased out under the Montreal Protocol, an international environmental agreement. Alternative substances with lower ozone depletion potential, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), have been developed and used as replacements for CFCs.

In conclusion, statement 1 is incorrect as CFCs do not contain calcium. Statement 2 is correct as CFCs are resistant to usual atmospheric scavenging processes, making them persistent and capable of causing damage to the ozone layer.

Explanation:

1. Ozone absorbs sunlight, causing the characteristic decrease in temperature with increase in altitude in the stratosphere:
This statement is correct. Ozone is a gas composed of three oxygen atoms (O3) and is found in the Earth's stratosphere. Ozone molecules in the stratosphere absorb ultraviolet (UV) radiation from the Sun, which causes a temperature increase in the ozone layer. This absorption of UV radiation by ozone prevents most of it from reaching the Earth's surface, protecting life on Earth from harmful UV radiation.

As altitude increases in the stratosphere, the concentration of ozone decreases. This decrease in ozone concentration leads to a decrease in temperature because there are fewer ozone molecules to absorb the sunlight and convert it into heat. Therefore, the characteristic decrease in temperature with increasing altitude in the stratosphere is caused by ozone absorbing sunlight.

2. The vortex is a ring of rapidly circulating air that confines the ozone depletion in the Antarctic region:
This statement is not correct. The vortex is not a ring of rapidly circulating air that confines ozone depletion in the Antarctic region. The correct term for this phenomenon is the "ozone hole."

The ozone hole is a region of exceptionally low ozone concentration in the stratosphere over the Antarctic during the Southern Hemisphere's spring (September to November). It is not caused by a vortex, but rather by chemical reactions involving man-made chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS). These substances are released into the atmosphere and eventually reach the stratosphere, where they break down ozone molecules.

The formation of the ozone hole is influenced by a combination of factors, including the presence of polar stratospheric clouds, low temperatures, and the unique atmospheric circulation patterns over the Antarctic. The "polar vortex" is a term used to describe the strong, persistent winds that encircle the polar regions, including the Antarctic. It is not the cause of the ozone hole but can contribute to its formation by isolating the Antarctic region and preventing the exchange of air with the rest of the atmosphere.

In conclusion, statement 1 is correct as ozone absorbs sunlight, causing the characteristic decrease in temperature with increasing altitude in the stratosphere. However, statement 2 is not correct as the vortex does not confine ozone depletion in the Antarctic region. The correct term for the phenomenon is the "ozone hole," which is primarily caused by chemical reactions involving ozone-depleting substances and is influenced by various atmospheric factors.

Understanding Bromine-Containing Compounds
Bromine-containing compounds play a significant role in various applications, particularly in fire suppression and refrigeration. In this context, let’s examine the two types of compounds mentioned: Halons and HBFCs.
1. Halons
- Definition: Halons are a group of brominated compounds used primarily as fire extinguishing agents.
- Composition: They typically contain bromine along with carbon and fluorine.
- Functionality: Halons are effective in suppressing fires due to their ability to interrupt the combustion process.
2. HBFCs (Hydrobromo Fluorocarbons)
- Definition: HBFCs are another class of bromine-containing compounds that include hydrogen, bromine, fluorine, and carbon.
- Application: They are used in refrigeration and as solvents, similar to other halogenated compounds.
- Environmental Impact: Like Halons, HBFCs have been scrutinized for their ozone-depleting potential.
Conclusion
Both Halons and HBFCs are recognized as bromine-containing compounds. They serve critical roles in fire suppression and refrigeration, respectively. The significance of these compounds extends to their environmental implications, particularly regarding ozone layer depletion.
Since both statements about Halons and HBFCs being bromine-containing compounds are correct, the right answer is:
Correct Answer: c) Both of them

Explanation:

1. Rate of Ozone Destruction:
- The statement is correct as the rate at which ozone is being destroyed is indeed much faster than the rate at which it is being formed.
- Ozone depletion is primarily caused by human-made chemicals like chlorofluorocarbons (CFCs) and halons, which break down ozone molecules in the stratosphere.

2. Ozone Depletion over Antarctic:
- The statement is also correct as the best example of ozone depletion is the ozone hole that forms over the Antarctic region.
- The Antarctic ozone hole is a severe depletion of the ozone layer above Antarctica that occurs during the Southern Hemisphere spring (September-November).
- The ozone hole is characterized by extremely low ozone concentrations, with levels dropping to about 50% of their pre-1980 levels.

Conclusion:
- Both statements are correct as they highlight the significant issue of ozone depletion, especially over the Antarctic region where ozone levels have been drastically reduced. This depletion has serious implications for human health and the environment.

Understanding Ocean Acidification
Ocean acidification is a significant environmental issue caused by the absorption of excess atmospheric CO2 by the oceans. This process lowers the pH of seawater, adversely affecting marine ecosystems, particularly organisms like corals and shellfish that rely on calcium carbonate.
Measures to Mitigate Ocean Acidification
To combat ocean acidification, the following measures are crucial:
1. Reducing CO2
- Lowering carbon dioxide emissions is fundamental to addressing ocean acidification. As CO2 levels decrease in the atmosphere, less of it is absorbed by the oceans, resulting in reduced acidification.
2. Promoting Government Policies to Cap CO2 Emissions
- Implementing government policies that set limits on CO2 emissions can lead to a significant decrease in atmospheric CO2 levels. Such initiatives may include carbon pricing, renewable energy incentives, and stricter regulations on fossil fuel use.
3. Eliminating Offshore Drilling
- Offshore drilling contributes to greenhouse gas emissions and poses risks of oil spills, which can harm marine life. By phasing out offshore drilling, we can reduce CO2 emissions and protect ocean ecosystems from potential contamination.
Conclusion
All three measures—reducing CO2, promoting government policies to cap emissions, and eliminating offshore drilling—are effective strategies to mitigate the effects of ocean acidification. Therefore, the correct answer is option 'D': all of the above. By implementing these measures collectively, we can work towards healthier oceans and a more sustainable future.