Combined use of geophysical and geochemical methods to assess areas of active, degrading and restored blanket bog

Abstract

Here we combine the use of geo-electrical techniques with geochemical analysis of the solid and liquid phase to determine subsurface properties and general peatland health. Active, degrading and restored peat locations were analysed from the same blanket bog site (ensuring they were under the same environmental conditions, such as rainfall and temperature) at the Garron Plateau, Northern Ireland. A normalized chargeability (ratio of resistivity (inverse of conductivity) and chargeability) profile was compared with organic composition analysis of the solid and liquid phases from active, degrading and restored locations. Results show that the degrading location is undergoing high rates of decomposition and loss of organic matter into the interstitial water, whereas the opposite is true for the active location. The restored peat is showing low rates of decomposition however has a high concentration of organic material in the porewater, primarily composing long chain aliphatic compounds, sourced from vascular plants. The ingression of vascular plants permits the diffusion of oxygen via roots into the subsurface and supports the oxidation of phenols by phenol oxidase, which produces phenoxy radicals and quinones (CO double bonds). This production of conjugated quinones, which are characterized by a CO double bond, in the aerated degrading and restored locations, increase the polarity, cation exchange capacity, and the normalized chargeability of the peat. This higher chargeability is not evident in the active peat due to decreased aerobic decomposition and a domination of sphagnum mosses.

Keywords: Conductivity; Drainage; Normalized chargeability; Phenol oxidase; Quinones; Vascular ingression.