Fig. 4. Relationship between topography and redox regime. The oxidation-reduction values distribution in form of box plots (see legend) (a) Polygon 1 and (c) Polygon 2. Cross section through studied low-center polygons with morphological units and installation depths (points filled in black) of the lower electrodes (directly above the permafrost table), (b) Polygon 1 (day of installation 28 June 1999), (d) Polygon 2 (day of installation 30 July 2000).