What do high levels of CO2 in water cause

As it combines with water, it forms carbonic acid, making the blood acidic. So CO2 in the bloodstream lowers the blood pH. When CO2 levels become excessive, a condition known as acidosis occurs. This is defined as the pH of the blood becoming less than 7.35.

Explanation:

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.