Dissolved inorganic carbon

Definition

Dissolved inorganic carbon (DIC) refers to the forms of carbon found in ocean water, mainly consisting of carbon dioxide (CO2), bicarbonate (HCO3^-), and carbonate ions (CO3^2-). These forms of carbon play a crucial role in the ocean's carbon cycle, influencing both the chemistry of seawater and the processes that contribute to ocean acidification.

5 Must Know Facts For Your Next Test

1. Approximately 90% of dissolved inorganic carbon in seawater is in the form of bicarbonate ions, with carbonate and dissolved CO2 making up the remainder.
2. DIC concentrations are influenced by biological processes like photosynthesis and respiration, as well as physical processes such as upwelling and mixing.
3. The dissolution of CO2 in ocean water leads to a decrease in pH, contributing to ocean acidification, which adversely affects calcifying organisms like corals and shellfish.
4. Monitoring DIC levels is essential for understanding the health of marine ecosystems and their responses to climate change.
5. Dissolved inorganic carbon plays a key role in buffering ocean pH levels, helping to stabilize the chemistry of seawater despite varying CO2 concentrations.

Review Questions

• How does dissolved inorganic carbon influence the chemical balance of ocean waters?
  • Dissolved inorganic carbon influences the chemical balance of ocean waters primarily by affecting pH levels through the equilibrium between CO2, bicarbonate, and carbonate ions. When CO2 is absorbed by seawater, it reacts with water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions, lowering the pH. This shift not only affects the carbonate chemistry but also has implications for marine organisms that rely on stable pH for growth and survival.
• Discuss the relationship between dissolved inorganic carbon and ocean acidification, including its effects on marine life.
  • The relationship between dissolved inorganic carbon and ocean acidification stems from the absorption of excess atmospheric CO2 by oceans. As CO2 dissolves in seawater, it increases DIC levels and contributes to the formation of carbonic acid, resulting in lower pH values. This acidification poses significant threats to marine life, particularly organisms that depend on calcium carbonate for their shells or skeletons. A more acidic environment hinders their ability to calcify, potentially leading to declines in populations such as corals and shellfish.
• Evaluate the importance of monitoring dissolved inorganic carbon levels in understanding climate change impacts on marine ecosystems.
  • Monitoring dissolved inorganic carbon levels is crucial for evaluating climate change impacts on marine ecosystems because it provides insights into how increased atmospheric CO2 concentrations affect ocean chemistry. Changes in DIC can influence nutrient availability and biological productivity, affecting food webs and ecosystem dynamics. Furthermore, understanding DIC fluctuations helps predict how marine organisms adapt or decline in response to ongoing ocean acidification, allowing scientists to implement better conservation strategies and manage fisheries sustainably amid changing environmental conditions.

Related terms

Carbon cycle: The series of processes by which carbon compounds are interconverted in the environment, including respiration, photosynthesis, and decomposition.

Ocean acidification: The decrease in pH levels of ocean water caused by the absorption of excess atmospheric CO2, leading to harmful effects on marine life.

pH: A measure of the acidity or alkalinity of a solution, where lower values indicate higher acidity.