Aragonite

Definition

Aragonite is a mineral form of calcium carbonate (CaCO₃) that is less stable than its polymorph calcite. It plays a significant role in biomineralization, as many marine organisms utilize aragonite to form their shells and skeletons, contributing to the biogeochemical cycling of carbon in marine ecosystems.

5 Must Know Facts For Your Next Test

1. Aragonite is less stable than calcite, which means it can convert into calcite over geological time scales through diagenesis.
2. Many marine organisms, including mollusks and corals, preferentially deposit aragonite due to its favorable properties for forming protective structures.
3. Aragonite plays a critical role in the ocean's carbonate chemistry, acting as a buffer for pH levels and influencing the overall health of marine ecosystems.
4. The solubility of aragonite is higher than that of calcite, making it more susceptible to dissolution in acidic conditions, which poses challenges for organisms in changing ocean environments.
5. Understanding the formation and stability of aragonite is essential for predicting how marine life will respond to climate change and ocean acidification.

Review Questions

• How do marine organisms utilize aragonite in their physiological processes?
  • Marine organisms like mollusks and corals utilize aragonite to form their shells and skeletons. This mineral provides structural support and protection against predators and environmental factors. The ability to produce aragonite through biomineralization enables these organisms to thrive in various marine environments, showcasing the intricate relationship between biology and geology.
• Evaluate the implications of aragonite's solubility in relation to climate change and ocean acidification.
  • Aragonite's higher solubility compared to calcite means that it is more vulnerable to dissolution in acidic conditions, which are becoming more prevalent due to climate change. This poses significant risks for marine organisms that rely on aragonite for their structural integrity. As ocean acidity increases, the ability of these organisms to produce and maintain aragonite structures could be compromised, leading to broader ecological consequences in marine ecosystems.
• Synthesize information on the role of aragonite in the biogeochemical cycling of carbon and discuss its significance for marine ecosystems.
  • Aragonite plays a pivotal role in the biogeochemical cycling of carbon by acting as a carbon sink when marine organisms sequester carbon dioxide from the atmosphere to form calcium carbonate structures. As these organisms die and their aragonite shells sink to the ocean floor, they effectively remove carbon from the surface environment, helping to regulate atmospheric CO₂ levels. This process is crucial for maintaining ocean health and balance within marine ecosystems, especially in light of ongoing changes due to human activity.

Related terms

Biomineralization: The process by which living organisms produce minerals to harden or stiffen existing tissues, often seen in the formation of shells and skeletons.

Calcification:

The accumulation of calcium carbonate in an organism's tissues, often resulting in the formation of hard structures like shells or corals.

Marine Carbonate System: The interplay of carbon dioxide, bicarbonate, carbonate ions, and calcium in seawater that regulates ocean chemistry and influences biological processes.