Warren W. Wood 1976 The unstable nature of many chemical and physical constituents in ground water requires special collection procedures and field analysis immediately after collection. This report describes the techniques and equipment commonly used m the collection and field analysis of samples for pH, temperature, carbonate, bicarbonate, specific conductance, Eh, and dissolved oxygen. application/pdf 10.3133/twri01D2 en U.S. Geological Survey Guidelines for collection and field analysis of ground-water samples for selected unstable constituents reports