Stratospheric Ozone Depletion and Reducing Ozone Depletion: Practice Questions

• a.Terrestrial ice melting leads to a decrease in ocean salinity which decreases the total volume of the ocean through chemical contraction.
• b.Thermal expansion increases the volume of existing ocean water due to kinetic energy changes, while melting terrestrial ice adds new mass to the ocean basins.
• c.Thermal expansion only affects the surface layer of the ocean, whereas melting ice sheets affect the deep ocean currents.
• d.Melting sea ice is the primary driver of sea-level rise compared to terrestrial ice because sea ice has a higher density.

• a.

  Methane release increases ocean acidity, which prevents phytoplankton growth, reducing the biological pump's ability to sequester carbon.

• b.

  Increased atmospheric temperatures lead to ocean warming, which destabilizes methane hydrates, releasing \( CH_4 \) that further enhances the greenhouse effect.

• c.

  Methane reacts with stratospheric ozone to form water vapor, which increases cloud albedo and leads to a net cooling effect.

• d.

  The release of methane stimulates the growth of methanotrophic bacteria, which consume dissolved oxygen and cause mass extinction events.

• a.They provide a catalytic surface for chemical reactions that convert inactive reservoir chlorine compounds into highly reactive chlorine gas.
• b.They directly react with ozone molecules in a combustion-like reaction, breaking \(O_{3}\) down into \(O_{2}\) and atomic oxygen.
• c.They trap methane and carbon dioxide in the upper atmosphere, leading to an increase in the global temperature and the thinning of the ozone layer.
• d.They absorb ultraviolet radiation, which prevents the ozone layer from regenerating during the winter months.

• a.Increased \(H^{+}\) ion concentration shifts the equilibrium \(HCO_{3}^{-} \rightleftharpoons H^{+} + CO_{3}^{2-}\) toward the left, decreasing the availability of \(CO_{3}^{2-}\) for shell formation.
• b.The rise in \(CO_{2}\) increases the concentration of \(CO_{3}^{2-}\) ions, leading to the over-calcification and eventual death of phytoplankton.
• c.Increased \(CO_{2}\) reacts directly with calcium carbonate shells to produce calcium bicarbonate, which increases the pH of the ocean water.
• d.Increased \(H^{+}\) ions react with \(OH^{-}\) ions to form water, which reduces the salinity of the ocean and causes osmotic stress in coral reefs.

• a.\(\text{Cl} + \text{O}_3 \rightarrow \text{ClO} + \text{O}_2\) followed by \(\text{ClO} + \text{Cl} \rightarrow \text{Cl}_2 + \text{O}\)
• b.\(\text{Cl} + \text{O}_2 \rightarrow \text{ClO}_2\) followed by \(\text{ClO}_2 + \text{UV} \rightarrow \text{Cl} + \text{O}_2\)
• c.\(\text{CFC} + \text{O}_3 \rightarrow \text{CFCl} + \text{O}_2\) followed by \(\text{CFCl} + \text{O} \rightarrow \text{CFC} + \text{O}_2\)
• d.\(\text{Cl} + \text{O}_3 \rightarrow \text{ClO} + \text{O}_2\) followed by \(\text{ClO} + \text{O} \rightarrow \text{Cl} + \text{O}_2\)

Write your answer out first, then check it against the worked solution.