Dissolution of calcium carbonate

Definition

The dissolution of calcium carbonate refers to the process by which calcium carbonate (CaCO₃) dissolves in water, particularly in the presence of carbonic acid formed when CO₂ is dissolved in water. This process is crucial in understanding how ocean acidification affects marine ecosystems, especially those involving organisms that rely on calcium carbonate for their shells and skeletons, such as corals and mollusks.

5 Must Know Facts For Your Next Test

1. As CO₂ levels rise in the atmosphere, more CO₂ dissolves in ocean waters, increasing the formation of carbonic acid and lowering the pH, which enhances the dissolution of calcium carbonate.
2. The dissolution of calcium carbonate negatively impacts calcifying organisms, leading to weaker shells and skeletons, making them more vulnerable to predation and environmental stressors.
3. Coral reefs are particularly at risk from increased dissolution, as they rely on calcium carbonate to build their structures; decreased availability may hinder their growth and resilience.
4. The rate of dissolution can vary based on local conditions such as temperature, salinity, and organic matter content, all of which influence the overall health of marine ecosystems.
5. Monitoring the saturation state of aragonite and calcite helps scientists predict how changes in ocean chemistry affect marine life and overall biodiversity.

Review Questions

• How does the increase in atmospheric CO₂ relate to the dissolution of calcium carbonate in marine environments?
  • When atmospheric CO₂ levels rise, a significant portion is absorbed by the oceans. This process results in an increase in carbonic acid concentration in seawater, which lowers the pH. As the pH decreases, the chemical equilibrium shifts towards increased dissolution of calcium carbonate, which can have detrimental effects on marine organisms that depend on this compound for their structures.
• Discuss the implications of calcium carbonate dissolution for coral reef ecosystems.
  • The dissolution of calcium carbonate poses a serious threat to coral reef ecosystems. As coral polyps use calcium carbonate to build their skeletons, increased dissolution leads to weaker structures and reduced growth rates. This vulnerability not only affects individual corals but also compromises the entire reef system's integrity, biodiversity, and resilience against environmental changes.
• Evaluate the broader ecological consequences of continued calcium carbonate dissolution in oceans affected by acidification.
  • Continued calcium carbonate dissolution due to ocean acidification will likely lead to significant ecological changes. The decline of calcifying organisms like corals and mollusks can disrupt food webs and reduce biodiversity. This loss impacts species that rely on these organisms for habitat or food. Furthermore, weakened coral reefs lead to diminished coastal protection against storms and erosion, resulting in socioeconomic challenges for human communities dependent on healthy marine ecosystems for livelihoods and tourism.

Related terms

Ocean acidification: The decrease in pH of the ocean caused by increased absorption of atmospheric CO₂, leading to higher concentrations of carbonic acid in seawater.

Calcifying organisms: Marine organisms that produce calcium carbonate structures, including corals, mollusks, and some plankton species, which are significantly affected by changes in ocean chemistry.

Calcium carbonate saturation state: A measure of the thermodynamic potential for calcium carbonate to precipitate or dissolve in seawater, indicating the balance between dissolved ions and solid carbonate minerals.