MEASUREMENT & RELATIONSHIP OF PHYSICAL CHEMICAL PARAMETERS (Cont)
pH: The pH of aqueous solution is controlled by the interrelated chemical reactions that produce or consume hydrogen ions. The pH of a solution is a measure of the effective hydrogen-ion concentration. More specifically, pH is a measure that represents the negative base-10 logarithm of hydrogen-ion activity of a solution, in moles per liter. Solutions having a pH below 7 are described as acidic, and solutions with pH greater than 7 are described as basic or alkaline. .
The electrometric pH-measurement method, using a hydrogen-ion electrode, commonly is used in continuous water-quality pH sensors.
A correctly calibrated pH sensor can accurately measure pH to -+ 0.2 pH units; however, the sensor can be stretched, broken or fouled easily. If the streamflow rates are high, the accuracy of the pH measurement can be affected by streaming-potential effects.