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

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.

Organic composition and multiphase stable isotope analysis of active, degrading and restored blanket bog.

Here we used organic composition and stable isotopic analysis to evaluate the effects of drainage and restoration at an ombrotrophic peatland, to assess whether rewetting of blanket bogs will reverse degradation. The organic composition of the peat and the isotopic fractionation between the solid (peat), liquid (pore water) and gas (soil gas) phases on actively accumulating, degrading and restored locations are compared. Fourier Transform Infrared Spectroscopy (FTIR) analysis of the organic material has shown a high level of humification (low decomposition) in the active peat. Stable isotope analysis in the solid, liquid and gas phases has corresponded with this and indicated that the active location is enriched in 13C in the solid and gas phases, 15N in the solid phase, 18O in the liquid and gas phases and D in the liquid phase, suggesting a closed system with limited isotopic fractionation and thus limited water movement and decomposition. The degrading location has a lower level of humification, and is depleted in 13C in the solid phase due to ingression of vascular plants. The restored location has high humification and enrichment of 13C and 15N in the solid phase, and D in the liquid phase suggesting increased microbial activity. 13C and 18O in the gas phase and 18O in the liquid phase are depleted, as a result of microbial mediated gas production and rewetting. FTIR analysis has also indicated a subsurface zone of increased decomposition between the acrotelm and catotelm in both the active and degrading peat. This is due to a stable water table and is not present within the restored location, which we attribute to water table fluctuation associated with rewetting. This zone of increased decomposition adds to the complexity of blanket bog peatlands and the assumption that all systems can be generalized under one conceptual model.