Acidification

• Main Author: Riebesell, Ulf
• Other Authors: Harff, J., Meschede, M., Petersen, Sven, Thiede, Jörn
• Format: Book Part
• Language: English
• Published: Springer 2015
• Subjects: Carbonic acid; Ocean acidification
• Online Access: https://oceanrep.geomar.de/id/eprint/30586/; https://oceanrep.geomar.de/id/eprint/30586/1/Riebesell.pdf; https://doi.org/10.1007/978-94-007-6644-0_39-4

Definition Ocean acidification refers to the process of increasing seawater acidity by dissolving additional carbon dioxide (CO2) from the atmosphere. As CO2 dissolves in seawater, it forms carbonic acid (H2CO3), which readily dissociates into bicarbonate (HCO3−) and hydrogen (H+) ions. The hydrogen ion concentration determines the acidity of seawater, expressed by the pH scale. Part of the hydrogen ions released in this process is buffered by the seawater carbonate system by consuming carbonate ions (CO32−) and forming additional bicarbonate. As pH is defined as the negative logarithm of the hydrogen ion concentration, pH decreases as the acidity increases (Fig. 1). Fig. 1 The process of ocean acidification: (1) atmospheric carbon dioxide (CO2) dissolving in seawater; (2) dissolved CO2 reacting with water to form carbonic acid (H2CO3); (3) carbonic acid dissociating to bicarbonate (HCO3−) and hydrogen ion (H+); and (4) hydrogen ion reacting with carbonate (CO3 . This is an excerpt from the content