P/M Speciation Relationships

Definition

The set of rules comparing P-alkalinity to M-alkalinity to determine the hydroxide, carbonate, and bicarbonate breakdown of a water.

If P equals 0 all alkalinity is bicarbonate; if P is less than half M it is a bicarbonate-carbonate mix; if P equals half M it is all carbonate; if P is greater than half M it is a carbonate-hydroxide mix; and if P equals M it is all hydroxide. The accompanying table gives the species amounts, for example carbonate equal to 2P and bicarbonate equal to M minus 2P in the bicarbonate-carbonate case. These relationships convert two field titrations into a full speciation picture.

Related concepts

P- and M-alkalinity Titration · M-alkalinity · Half-Carbonate Behavior

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Part of The Blueprint of Water · 📏 measurement