Question

Depletion of the stratospheric ozone layer occurs when molecules of ozone are destroyed by chemicals such as... A. CFC B. DDT ?. \(\mathrm{O}_{3}\) D. \(\mathrm{PCB}\) E. \(\mathrm{CH}_{4}\)

Short answer

A. CFC

Step-by-step solution

Identify the Key Concept

Understand that the exercise is about the depletion of the stratospheric ozone layer and the chemicals responsible for this process.

List the Chemicals Known for Ozone Depletion

Recall that certain chemicals, such as chlorofluorocarbons (CFCs), are known to cause significant depletion of the stratospheric ozone layer.

Evaluate Each Option

Consider each of the given options to identify the one directly linked to ozone layer depletion: A. CFC - Known for causing ozone depletion. B. DDT - A pesticide, but not linked to ozone depletion. C. \(\text{O}_3\) - Ozone itself, not a depleting agent. D. PCB - Chemicals harmful to health but not linked to ozone depletion. E. \(\text{CH}_4\) - Methane, contributes to greenhouse effect but not directly to ozone depletion.

Select the Correct Answer

Based on the evaluations, the chemical that is directly responsible for the depletion of the ozone layer is CFC.

Key concepts

chlorofluorocarbons (CFCs)

Chlorofluorocarbons (CFCs) are synthetic compounds made up of chlorine, fluorine, and carbon. They were once widely used in products like air conditioners, refrigerators, and aerosol sprays due to their stability and non-flammability. Unfortunately, this chemical stability also allows CFCs to rise into the stratosphere where they cause significant harm.

When CFCs reach the stratosphere, ultraviolet (UV) radiation from the sun breaks them down. This process releases chlorine atoms, which then react with ozone (O3) molecules, causing the ozone molecules to break apart. The net result is a thinning of the ozone layer, which leads to an increase in the amount of harmful UV-B radiation reaching the Earth’s surface. This increase in UV-B radiation can lead to higher rates of skin cancer, cataracts, and other health problems, as well as damaging ecosystems and wildlife.

Due to their harmful effects, the production of CFCs has been largely phased out under international agreements, such as the Montreal Protocol. However, existing CFCs can remain in the atmosphere for many years, continuing to contribute to ozone depletion even today.

ozone layer

The ozone layer is a region of the Earth's stratosphere that contains a high concentration of ozone (O3) molecules. It acts as a protective shield, absorbing the majority of the sun’s harmful ultraviolet (UV) radiation. Without the ozone layer, life on Earth would be at greater risk from UV radiation.

The importance of the ozone layer became evident when scientists discovered that it was being depleted by chemicals like chlorofluorocarbons (CFCs). When these chemicals reach the stratosphere, they release chlorine atoms that react with ozone molecules, breaking them apart.

This process creates what is known as an 'ozone hole,' particularly observed over Antarctica. The thinning of the ozone layer leads to an increase in UV-B radiation reaching the Earth’s surface, resulting in various environmental and health consequences.

• Harm to marine ecosystems: Increased UV-B can affect the productivity of phytoplankton, the base of the marine food web.
• Damage to terrestrial plant life: Excessive UV-B radiation can inhibit plant growth.
• Health risks: Increased UV-B exposure leads to higher rates of skin cancer and cataracts in humans.

Protecting the ozone layer remains a vital effort, with international steps like the Montreal Protocol aiming to phase out ozone-depleting substances.

environmental science

Environmental science is a multidisciplinary field that studies the interaction between natural systems and human activities. It aims to understand how humans impact the environment and how these impacts can be managed and mitigated. One key area of study within environmental science is the depletion of the ozone layer, which has significant implications for both human health and ecosystems.

By studying environmental issues like ozone depletion, scientists can develop strategies to protect the environment. This has led to international agreements such as the Montreal Protocol, which has successfully reduced the production of many ozone-depleting substances.

• Research: Environmental scientists use data from satellites, ground stations, and other sources to monitor ozone levels and track changes over time.
• Policy development: Scientific findings inform policies and regulations aimed at protecting the ozone layer and reducing harmful emissions.
• Public awareness: Educating the public about the importance of the ozone layer and the steps they can take to protect it is crucial for long-term environmental health.

Environmental science continues to play a vital role in addressing global challenges, promoting sustainable practices, and ensuring a healthy planet for future generations.