Measurement of soil redox and electrodes

Platinum and suitable reference electrodes are relatively easy and inexpensive to construct, but the measurement technique may significantly alter measured voltages. Quantification of H2 may be more reliable than Eh measurements for identifying anoxic redox process. Quantification of H2 may be achieved by using a gas-stripping procedure by N2 displacement following sample collection (Chapelle etal. 1996). However, because of complexities in interpretation, 

The limitations have been described (James Bartlett 2000), especially with respect to how long the electrodes can be left in place in the soil and with respect to interpreting the Eh values obtained. A specific limitation relates to the inadequacy of Pt electrode potential measurement. 

Other electrodes which have been examined are as follows graphite electrodes, simple Ag, AgCl reference electrodes (Farrell etal. 1991) microelectrodes constructed from micropipets (Pang Zhang 1998 Shaikh etal. 1985). James and Bartell (2000) also list several general reviews and examples of redox measurements. 

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