the acid neutralizing capacity of a water. It is
usually expressed as "M" alkalinity (the methyl orange
endpoint at a pH @ 4.3) and "P" alkalinity (the phenolphthalein
endpoint at a pH @ 8.3).
Several ions contribute to alkalinity, but it is generally
due to bicarbonate (HCO3
–1), carbonate (CO3
–2), and hydroxyl
(OH–1) ions.