Buffers

Understanding Buffers

  • A buffer is a solution that can resist drastic changes in pH upon the addition of small amounts of acid or base.

  • Buffers are made up of a weak acid and its conjugate base or a weak base and its conjugate acid. In an aqueous solution, both the acid/base and its conjugate are present and work together to moderate pH changes.

  • The chemical equilibrium between the weak acid/base and its conjugate allows for the uptake or release of protons (H+) in response to changes in the solution’s pH.

Buffers in the Ocean

  • One prominent example of buffers in natural systems is the carbonate buffer system in the ocean.

  • This buffering system includes several chemical species: carbon dioxide (CO2), carbonic acid (H2CO3), bicarbonate ions (HCO3-), and carbonate ions (CO3–).

  • These components exist in equilibrium with each other and with pH changes in the water, which continually drives reactions in one direction or the other, effectively diminishing substantial pH swings.

  • The predominant buffer in ocean waters is the bicarbonate ion (HCO3-).

Effects of Ocean Acidification on Buffering Capacity

  • The ongoing absorption of anthropogenic CO2 by the ocean, which forms additional carbonic acid, is shifting this equilibrium and causing ocean acidification.

  • As more CO2 is absorbed, more carbonic acid is formed, which further dissociates into bicarbonate ions and protons, thus increasingly acidity and potentially exhausting the buffering capacity of seawater.

  • As this pH lowering continues, the ocean’s natural buffer system becomes less effective since it is not able to keep up with the growing quantity of absorbed CO2.

Implications of Reduced Buffering Capacity

  • As the buffering capacity is diminished, the risk of drastic changes in ocean pH increase, with potentially severe repercussions for marine life and ecosystems.

  • Significant pH decreases can affect the biological activity of marine organisms, including their metabolic rates, reproduction, and growth.

  • Humans are also implicated in these changes, as they rely heavily on marine ecosystems for food, employment, and economic activity. Understanding the oceanic buffer system and human impacts on it is therefore crucial for addressing these global problems.