Ocean Acidification | Ocean carbon sink | Causes of Ocean Acidification

What is Ocean Acidification?

Ocean acidification occurs due to the change in ocean chemistry which happens due to the uptake of atmospheric chemicals like carbon, sulfur, and nitrogen. The anthropogenic release of carbon dioxide (CO2) is the dominant cause of ocean acidification while in several coastal areas, sulfur and nitrogen are also significant.

The ocean is a sink of Carbon:

The ocean absorbs atmospheric carbon dioxide (CO2).
Carbon capture and storage is called carbon sequestration.
Oceans capture and store carbon from the atmosphere.

Causes of Ocean Acidification:

For the past 200 years, the rapid increase in anthropogenic atmospheric CO2, which directly leads to decreasing ocean pH through an air-sea gas exchange, has been and continues due to the following reasons.
The rapid increase in atmospheric CO2 in the past 200 years due to anthropogenic activities is the leading factor in decreasing ocean pH due to air and sea gas exchange. The primary causes of ocean acidification are as follows.

• Combustion of fossil fuel
• Cutting of forest (Deforestation)
• Industrialization
• Production of cement
• Land-use changes                                                                                           

How carbon dioxide (CO2) is the main cause of ocean acidification?  (Chemical reaction)

When CO2 dissolves in seawater, carbonic acid is produced via the reaction:

In seawater CO2 dissolves and form carbonic acid through the reaction below:

CO2 + H2O.................................  H2CO3

The carbonic acid splits in seawater and releases hydrogen ions and bicarbonate:

H2CO3......................................H+ + HCO3-

The increased concentration of hydrogen ions in seawater increases acidity in oceans. 

The result of the release of hydrogen ions in seawater is that it reacts with any carbonate ion and forms bicarbonate.

H⁺+ CO ₃^2--.................................H2CO3-

The above phenomena remove carbonate ions from seawater and it creates difficulty for aquatic organisms to form calcium carbonate (CaCO3) which is necessary for their shell formation.

How aquatic life affected by ocean acidification? 

The ocean acidification affects some species of microscopic algae and calcifying plankton which are the base of marine chain and food for larger organisms i.e. fish and whales. The equilibrium chemical condition and pH level are important to build calcium-based shells and other structures for many seawater organisms like clams, mussels, sea urchins, microscopic plankton, etc. Ocean acidification affects their growth, reproduction, and survival in such a particular environment.

 

Conclusion:

The ocean acidification will diminish the ocean's capability to capture and store atmospheric carbon and it will severely affect marine life. If concrete steps will not take to curb ocean acidification then its repercussions will be felt by the global economy by disrupting the food chain.