IB Environmental systems and societies Topic 6.4B Ozone Depletion Revision Notes (SL/HL)

IB Environmental systems and societies Topic 6.4B Ozone Depletion Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Ozone’s Natural Balance: Formation Equals Destruction

Stratospheric ozone has stayed roughly constant for thousands of years because ozone forms and is destroyed at the same rate.
Formation: UV splits oxygen molecules (O₂) into single oxygen atoms (O), which combine with more O₂ to make ozone (O₃).
Destruction: when ozone absorbs UV, it splits back into O₂ and a free O atom.
The freed oxygen atom can recombine with more oxygen, so the cycle sustains itself.
The result is a steady-state equilibrium where ozone destroyed equals ozone produced.
Ozone fluctuates by season and location, but stays stable under natural, pre-industrial conditions.

Note

This balance is not static.
It is a dynamic equilibrium, with formation and destruction happening constantly.

Ozone-Depleting Substances: How Humans Break the Balance

Definition

Ozone-depleting substances (ODSs)

Ozone-depleting substances (ODSs) are chemicals that accelerate ozone destruction beyond natural levels.

Ozone-depleting substances (ODSs) speed up ozone destruction, disrupting the natural equilibrium.
This tips the balance toward net ozone loss, especially over polar regions like Antarctica.
They include CFCs, halons, HCFCs, carbon tetrachloride and methyl bromide.
They became popular because they were non-toxic, non-reactive and excellent refrigerants, used in:
1. aerosols;
2. refrigeration and air-conditioning;

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Paywall

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Note

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Excepteur sint occaecat cupidatat non proident

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Tip

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Ozone’s Natural Balance: Formation Equals Destruction

Stratospheric ozone has stayed roughly constant for thousands of years because ozone forms and is destroyed at the same rate.
Formation: UV splits oxygen molecules (O₂) into single oxygen atoms (O), which combine with more O₂ to make ozone (O₃).
Destruction: when ozone absorbs UV, it splits back into O₂ and a free O atom.
The freed oxygen atom can recombine with more oxygen, so the cycle sustains itself.
The result is a steady-state equilibrium where ozone destroyed equals ozone produced.
Ozone fluctuates by season and location, but stays stable under natural, pre-industrial conditions.

Note

This balance is not static.
It is a dynamic equilibrium, with formation and destruction happening constantly.

Ozone-Depleting Substances: How Humans Break the Balance

Definition

Ozone-depleting substances (ODSs)

Ozone-depleting substances (ODSs) are chemicals that accelerate ozone destruction beyond natural levels.

Ozone-depleting substances (ODSs) speed up ozone destruction, disrupting the natural equilibrium.
This tips the balance toward net ozone loss, especially over polar regions like Antarctica.
They include CFCs, halons, HCFCs, carbon tetrachloride and methyl bromide.
They became popular because they were non-toxic, non-reactive and excellent refrigerants, used in:
1. aerosols;
2. refrigeration and air-conditioning;

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 6.4B Ozone Depletion Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Ozone’s Natural Balance: Formation Equals Destruction

Ozone-Depleting Substances: How Humans Break the Balance

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Ozone’s Natural Balance: Formation Equals Destruction

Ozone-Depleting Substances: How Humans Break the Balance

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account