When Carbon dioxide mixes with ocean water it lowers the pH and causes acidification. The level of atmospheric CO2 is increasing after industrial revolution . This increase in CO2 lowers the pH and hence the acidity. When CO2 reacts with H2O it forms weak carbonic acid. It furtherreacts with water to release bicarbonate ions and hydronium ions. This increasesacidity and creates a situation where there would be less of dissolved oxygen.These changes will have an unprecedented impact on marine life.
Effect of Ocean acidification:
- Oceans are an important reservoir for CO2, absorbing a significant quantity of it (one-third) produced by anthropogenic activities and effectively buffering climate change.
- The uptake of atmospheric carbon dioxide is occurring at a rate exceeding the natural buffering capacity of the oceans.
- Increasing acidity depresses metabolic rates and immune responses in some organisms.
- Seawater absorbs CO2 to produce carbonic acid, bicarbonate and carbonate ions.
- However, the increase in atmospheric CO2 levels lead to a decrease in pH level, an increase in the concentration of carbonic acid and bicarbonate ions, causing a decrease in the concentration of carbonate ions.
- The decrease in the amount of carbonate ions available makes it more difficult for marine calcifying organisms, such as coral (calcareous corals) and some plankton (calcareous plankton), to form biogenic calcium carbonate.
- Commercial fisheries are threatened because acidification harms calcifying organisms which form the base of the Arctic food webs.
- Increasing acidity accentuates coral bleaching as corals are very sensitive to changes in water composition.