GED Science TestEarth and Space ScienceMedium
A geochemist is studying the impact of increased atmospheric carbon dioxide on marine ecosystems. They observe that as more CO2 dissolves into the ocean, the concentration of hydrogen ions (H+) in seawater increases. Which term best describes the resulting change in ocean chemistry?
- AEutrophication
- BOcean acidification
- CSalinization
- DThermal stratification
Show answer & explanationAnswer & explanation
Correct answer: B. Ocean acidification
When carbon dioxide (CO2) dissolves in seawater, it forms carbonic acid (H2CO3). This acid then dissociates, releasing hydrogen ions (H+) and decreasing the pH of the ocean, a process known as ocean acidification. This increase in H+ ions is the defining characteristic of acidification.
Why the other options are wrong
- A. Eutrophication is nutrient enrichment leading to algal blooms and oxygen depletion.
- C. Salinization is an increase in salt concentration.
- D. Thermal stratification is the layering of water based on temperature differences.
Ocean Acidification
The ongoing decrease in the pH of Earth's oceans, caused by the absorption of excess carbon dioxide (CO2) from the atmosphere.
- CO2 dissolves in seawater to form carbonic acid.
- Carbonic acid releases hydrogen ions (H+), lowering pH.
- Impacts marine organisms, especially those with calcium carbonate shells or skeletons.
Memory trick: Carbon's Ocean Dive, pH Takes a Nosedive.