Ocean acidification

What is ocean acidification?

Ocean is the main source which sinks atmospheric CO₂. Ocean absorbs nearly 30% of the CO₂ that is released to the atmosphere. CO₂ is common in Earth’s atmosphere. Both plants and animals need CO₂. Plants need CO₂ for the photosynthesis and growth. In respiration animals exhale CO₂. Since the beginning of the industrial era the amount of CO₂ emitted to the atmosphere has increased because of the burning of fossil fuels and the increase of population. So, the amount of CO₂ absorb by the ocean is high. This cause the drop of the ocean’s pH. value. Normally the pH. value of the ocean is between 8.0-8.3. that means its little bit alkaline.

When CO₂ dissolves in ocean a series of chemical reactions happen. It forms Carbonic acid (H₂CO₃). This carbonic acid is weak and it releases hydrogen ions (H⁺).

CO_{2 (aq)} + H₂O _(l) ↔ H₂CO_{3 (aq)} ↔ HCO^-_{3 (aq)} + H⁺_(aq) ↔ CO^2-_3(aq) + 2H⁺_(aq)

So, the H⁺ concentration of the ocean water increases and it lowers the pH. value of the ocean. This declining of the ocean’s pH. value is known as ocean acidification. Records shows that since the industrial revolution pH. has dropped from 8.2 to 8.1. some may think that the drop in the pH. of 0.1 is not a big issue. But the pH. scale is a logarithmic scale. The drop of the pH. value from one unit means the 10-fold increase in the hydrogen ion concentration. So, if the pH. decline in this rate it will cause long-term issues in the ocean ecosystem.

Impacts on the life in the ocean.

Ocean acidification may not harm all the organisms in the ocean, but it may badly affect some of them. This ocean acidification cause damage to the coral reefs. Corals form their skeleton by calcium carbonate. When the acidity of the ocean increases the calcium carbonate skeleton may corrode. And, it affects to the shell fish like oysters, mussels, clams, urchins, and starfish. Their shells also tend to dissolve because of the acidity. These shellfish face problems in building their shells because of the acidity in water. In acidic water mussels can’t hold into rocks well using their byssal threads.

Some crustaceans like crabs, shrimps and lobsters can grow stronger shells in acidic water and some organisms have adapted to higher acidity level in the ocean.

Zooplankton and phytoplankton like foraminifera, pteropods and coccolithophores also have CaCO₃ shells and that shells are damaged because of acidity. As they are important in food webs and primary productivity the whole ecosystem will face huge problems in future.

Precautions like implementing rules and regulations, educating people about the ocean acidification, reducing carbon footprint, reducing energy use and reducing electric usage cane be taken to minimize ocean acidification.