Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 67 Number 2: 127-132 - August 2005

A publication of the National Speleological Society

Measurement of pH for field studies in karst areas
Ira D. Sasowsky and Cory T. Dalton

Abstract

The determination of pH in karst waters is important for evaluating such chemical processes as cave growth, speleothem deposition, and overall water chemistry. Relatively small errors in pH readings can result in significant misinterpretations of the chemical processes taking place. For example, a pH error of 0.5 units would produce a correlative error in SIcalcite of 0.5. To ensure accuracy, pH must be measured in the field, but the conditions in karst settings make this hard to accomplish, and there is minimal published guidance available. Actions that help to improve data quality include: use of a good meter/electrode (accurate to 2 decimal places), careful preparation before field activities, cautious transport of instruments, frequent calibration, measurement in a beaker (not the water body), and allowance of time for equilibration. Instrumentation that allows measurement of very small samples, samples in wells, or continuous monitoring are available, but are more expensive and usually not as accurate.

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