Ocean Acidification

Required for Chemistry ATAR 12

What is ocean acidification?

The decrease in pH in the oceans due to absorption of CO2 from the atmosphere.

How can carbon in living organisms be stored after death?

If buried under layers of mud and sand, it can decompose and form fossil fuels like coal and oil.

What happens when fuels are burned?

Carbon dioxide (CO2) is released into the atmosphere.

What has significantly increased CO2 levels in the atmosphere?

The huge increase in burning fossil fuels.

What can trap heat in the atmosphere, affecting ocean temperatures?

CO2.

What is the symbiotic relationship between coral and zooxanthellae?

Coral provides a safe habitat and nutrients for zooxanthellae, which produce sugars for the coral via photosynthesis.

What occurs when ocean temperatures rise in relation to coral?

Algae separate from the coral, leading to coral bleaching and loss of color.

What percent of CO2 ends up in the ocean?

30%.

What is the equilibrium reaction that occurs when CO2 dissolves in water?

CO2 (aq) + H2O (l) ⇌ H2CO3 (aq).

What type of acid is H2CO3?

A weak diprotic acid.

What effect does increased CO2 have on ocean chemistry?

Shifts equilibrium to the right, increasing [H+] and lowering ocean pH.

What is the average current pH of the ocean?

8.1, expected to drop to 7.8 due to continued CO2 emissions.

What is calcification in marine animals?

The process where marine animals with shells rely on reactions between calcium and carbonate ions to form calcium carbonate shells.

How does increased acidification affect carbonate ions?

It shifts the equilibrium left, decreasing [CO3^2-] in the ocean.

What happens to calcium carbonate shells in acidic oceans?

Acids react with carbonates, leading to shell dissolution and weakening.

What is the reaction for the dissolution of calcium carbonate?

2H+ (aq) + CaCO3 (s) → Ca2+ (aq) + CO2 (g) + H2O (l).

What is the overall impact of reduced calcification on marine ecosystems?

It leads to destruction of species, disruption of the food chain, and decreased fish populations.

What is photosynthesis?

The process of taking CO2 from the atmosphere to make glucose using sunlight and chlorophyll.

What is the equation for photosynthesis?

6CO2 (g) + 6H2O (l) + ENERGY → C6H12O6 (aq) + 6O2 (g).

What is respiration in contrast to photosynthesis?

The exothermic reverse process of photosynthesis.

What is the enhanced greenhouse effect?

The process by which certain gases trap heat in the Earth's atmosphere, raising global temperatures.

What role do cold waters play in CO2 solubility?

CO2 is more soluble in cold water.

What are Champagne Sites?

Locations where large amounts of CO2 escape from undersea volcanoes, providing insights into future effects of increased CO2.

What is decalcification in oceans?

H+ (aq) + CO3^2- (aq) → HCO3- (aq); Additional H+ lowers carbonate concentration, making calcification difficult.

What impact does lowered pH have on marine life?

It decreases the rate of calcification and the ability for marine life to form calcium carbonate structures.

What can happen to fish populations due to these biochemical changes?

Decreased fish populations can impact commercial fisheries and the economies dependent on fishing.