Continuous Eh-recordings in sediment columns
© Biologischen Anstalt Helgoland 1975
Long-term recordings of redox-potential in marine sediments performed under laboratory conditions show that the drift of the measured potential after inserting the electrode cannot be neglected.
Cleaning and reinserting an electrode considerably changes the measured potential. This change may reach several hundred mV, depending on the position of the electrode and the composition of the sediment.
It takes several days until the potentials observed before cleaning are obtained again.
The overall Eh-profile in the sediment column is not changed by successive experiments. An electrode at a certain position in the sediment normally will return to the same potential if enough time is allowed for stabilization.
Quick measurements of single Eh-values in systems such as marine sediments must be handled with caution.
The measured shape of the redox-profile strongly depends on the time allowed for stabilization.
The position of the redox-potential-discontinuity defined as the point of inflection of the curve Eh versus depth seems to be the only meaningful parameter derived from quick measurements.