Question

Ocean acidification is caused by which of the following?

• A. SO$_2$
• B. CO$_2$
• C. NO$_x$
• D. O$_3$

Hint:

Ocean acidification: \[ \boxed{ \mathrm{CO_2} + \mathrm{H_2O} \rightarrow \mathrm{H_2CO_3} } \] Carbonic acid lowers the pH of seawater.

Answer 1

The Correct Option is B

Step 1: Think about what enters the ocean from the air.
The atmosphere constantly exchanges gases with the ocean surface, and one gas dissolves in seawater in large amounts because of the industrial emissions we produce.
Step 2: See what happens once that gas dissolves.
When $CO_2$ dissolves in water it reacts to form carbonic acid, $CO_2 + H_2O \rightarrow H_2CO_3$, and this acid breaks down further to release hydrogen ions.
Step 3: Connect this to acidification.
More hydrogen ions in seawater means a lower pH, and that drop in pH is exactly what we call ocean acidification. Rising atmospheric $CO_2$ from burning fossil fuels is the main driver behind it.
\[ \boxed{CO_2} \]