Construction and evaluation of redox electrode with summing operational amplifier: Application in study of methane emission

Measurements of redox potential (Eh) provide, qualitative information about oxidation-reduction conditions in hydromorphic soils. However, these measurements are confounded by several theoretical and technical complications. One seldom-discussed problem is interferences in consequence of static, capacitive or inductive coupling of stray fields (noise). This study developed an active redox electrode, which is immune against ambient noise coupling on the transmission line. An integrated voltage follower included into the electrode-body was used to decouple the sensitive high impedance primary circuit from all further devices of the signal chain. The electrode design was field-tested over four months. Trends of Eh on 12 electrodes of this design in a Fluvaquentic Humaquept are presented and discussed in relationship with changing of boundary conditions (precipitation, groundwater level) and emission of methane.