APES 9.1/9.2: Jackson M, Ryan F, Ryan G

Stratospheric ozone depletion

caused by ozone-depleting chemicals (ODCs) such as CFCs, methyl chloroform or trichloromethane (CHCl3), carbon tetrachloride (CCl4), halon (haloalkanes), methyl bromide (CH3Br)— all of which attack stratospheric ozone. The Cl or Br atoms "attack" the ozone molecules and cause the thinning of this layer.

stratospheric ozone

The ozone in the stratosphere 10 to 50 km above the earth's surface.

Ozone thinning is more pronounced at poles

-Sunlight needed to create O3 (no sun, no ozone)-Destruction is enhanced by colder temperatures
-Wind currents concentrate CFC's at poles

Excess UV exposure

Decreased photosynthesis on land and in the ocean. Can lead to mutations in skin cells that can result in skin cancer.

CFCs (chlorofluorocarbons)

chemicals used in coolants, solvents, and aerosol cans that damage the ozone layer.

stratospheric ice crystals

provide a site of conversion for chlorine-containing compounds that reduces ozone levels

What is the importance of stratospheric ozone to life on Earth?

The stratospheric ozone layer is important to the evolution of life on Earth and the continued health and survival of life on Earth.

What causes stratospheric ozone depletion?

Stratospheric ozone depletion is caused by anthropogenic factors, such as chlorofluorocarbons (CFCs) and natural factors, such as the melting of ice crystals in the atmosphere at the beginning of the Antarctic spring.

What are the common substitutes for CFCs?

HCFCs and CFCs

Are the substitutes for CFCs temporary or permanent?

They are temporary, as they deplete ozone but at a lesser speed

What are some ways that humans use chlorofluorocarbons (CFCs)?

CFCs are used as refrigerant chemicals and propellants in aerosol containers (hair spray, febreeze, etc)

What was the Montreal Protocol?

It was a international treaty to phase out the use of CFCs in global production.

What does carbonic acid (with increased hydrogen ions) bonded with carbonate form?

It forms bicarbonate/H2CO3

What do Cl atoms do to the ozone from CFCs?

It breaks down O3 into O2 over and over