Are there other sources of carbonate and bicarbonate, besides the common source calcium carbonate?

Document ID

Document ID TE119

Published Date

Published Date 27/05/2017
Question
Are there other sources of carbonate and bicarbonate, besides the common source calcium carbonate?
Summary
Other carbonate and bicarbonate sources of alkalinity
Answer
Another source of carbonate and bicarbonate is carbonic acid. Carbon dioxide and water are converted to carbonic acid through the following reaction:
CO2 + H2O -> H2CO3 (carbonic acid)

Carbonic acid provides bicarbonate and carbonate for buffering, just like CaCO3:
H2CO3 -> HCO3- + H+
HCO3- -> CO32- + H+

While conversion of carbon dioxide to carbonic acid produces ions capable of buffering pH, it also causes a decrease in pH (increase in H+) that CaCO3 does not. Notice in the reaction that as carbonic acid (H2CO3) reacts to form carbonate (CO32-), 2 hydrogen ions H+) are released into the water.