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Open-water perennial pools are common natural features of peatlands globally, and peatland restoration often results in new pool creation, yet the concentrations of different forms of aquatic carbon (C) in natural and artificial restoration pools are not well studied. We compared carbon concentrations in both natural pools and restoration pools (4–15 years old) on three blanket peatlands in northern Scotland. At all sites, restoration pools were more acidic and had mean dissolved organic carbon (DOC) concentrations in restoration pools of 23, 22, and 31 mg L−1 compared with natural pool means of 11, 11 and 15 mg L−1 respectively across the three sites. Restoration pools had a greater fulvic acid prevalence than the natural pools and their DOC was more aromatic. Restoration pools were supersaturated with dissolved CO2 at around 10 times atmospheric levels, whereas for natural pools, CO2 concentrations were just above atmospheric levels. Dissolved CH4 concentrations were not different between pool types, but were ~200 times higher than atmospheric levels. Regular sampling at one of the peatland sites over 2.5 years showed that particulate organic carbon (POC) concentrations were generally below 7 mg L−1 except during the warm, dry summer of 2013. At this regularly-sampled site, natural pools were found to process DOC so that mean pool outflow concentrations in overland flow were significantly lower than mean inflow DOC concentrations. Such an effect was not found for the restoration pools. Soil solution and pool water chemistry, and relationships between DOC and CO2 concentrations suggest that different processes are controlling the transformation of C, and therefore the form and amount of C, in natural pools compared to restoration pools.

We consider how the stoichiometry and energy content of organic matter reservoirs and fluxes through and from a peatland enable the fluxes and storage of carbon within a peatland to be constrained. We include the elemental composition of the above- and below-ground biomass, litter, the peat profile, and the dissolved and particulate organic matter within a blanket bog in northern England for which the C budget has previously been measured. The study shows, based only on the elemental composition, and calculation of oxidation and energy contents, that: (a) Dissolved organic carbon (DOC) in first-order streams is significantly more oxidized than in peat pore water but that there was no significant difference in organic carbon oxidation state down the peat profile; (b) The occurrence and speciation of N uptake and release in the peatland with N used and recycled can be predicted; (c) The relatively high oxidation state of DOC in stream water acts as an endpoint for peat-forming reactions; (d) Methanogenesis does not result in deep peat formation as its requirement for energy consumes too much organic matter to form residual peat at depth; (e) Sulfate reduction does occur during the formation of deep peat; (f) Organic matter elemental composition could be constrained to within three bounding equations though the proportions of carbon species could not be specified. (g) The formation of deep peat in this catchment could only be achieved if the dissolved organic matter (DOM) in the peat pore water is the dominant electron acceptor and energy source in the production of residual organic matter; however, it is unclear as to the flux of DOM up or down the peat profile.

The transformations and transitions of organic matter into, through, and out of an ecosystem must obey the second law of thermodynamics. This study considered the transition in the solid components of the organic matter flux through an entire ecosystem. Organic matter samples were taken from each organic matter reservoir and fluvial transfer pathway in a 100% peat‐covered catchment (Moor House National Nature Reserve, North Pennines, UK) and were analyzed by elemental analysis and bomb calorimetry. The samples analyzed were as follows: bulk aboveground and belowground biomass; individual plant functional types (heather, mosses, and sedges); plant litter layer; peat soil; and samples of particulate and dissolved organic matter (POM and DOM). Samples were compared to standards of lignin, cellulose, and plant protein. It was possible to calculate: enthalpy of formation, entropy of formation, and Gibbs free energy of formation for each of the samples and standards. The increase (decreasing negative values) in Gibbs free energy of formation through the ecosystem mean that for all but litter production, the transformations through the system must be balanced by production of low (large negative values) Gibbs free energy of formation products, not only CO2 or CH4 but also DOM. The change in Gibbs free energy of formation down the peat profile shows that reaction of the soil organic matter decreases or even ceases at depth and the majority of the reaction has occurred above 40 cm below the surface. This approach represents a new objective way to test and trace organic matter transformations in and through an ecosystem.

Perennial pools are common natural features of peatlands and their hydrological functioning and turnover may be important for carbon fluxes, aquatic ecology and downstream water quality. Peatland restoration methods such as ditch blocking result in many new pools. However, little is known about the hydrological function of either pool type. We monitored six natural and six artificial pools on a Scottish blanket peatland. Pool water levels were more variable in all seasons in artificial pools having greater water level increases and faster recession responses to storms than natural pools. Pools overflowed by a median of 9 and 54 times pool volume per year for natural and artificial pools respectively but this varied widely because some large pools had small upslope catchments and vice versa. Mean peat water-table depths were similar between natural and artificial pool sites but much more variable over time at the artificial pool site, possibly due to a lower bulk specific yield across this site. Pool levels and pool-level fluctuations were not the same as those of local water tables in the adjacent peat. Pool level time-series were much smoother, with more damped rainfall or recession responses than those for peat water tables. There were strong hydraulic gradients between the peat and pools, with absolute water tables often being 20-30 cm higher or lower than water levels in pools only 1-4 m away. However, as peat hydraulic conductivity was very low (median of 1.5×10-5 and 1.4×10-6 cm s-1 at 30 and 50 cm depths at the natural pool site) there was little deep subsurface flow interaction. We conclude that: 1) for peat restoration projects, a larger total pool surface area is likely to result in smaller flood peaks downstream, at least during summer months, because peatland bulk specific yield will be greater; and 2) surface and near-surface connectivity during storm events and topographic context, rather than pool size alone, must be taken into account in future peatl

Peatlands can accumulate organic matter into long-term carbon (C) storage within the soil profile. This study used solid-state 13C nuclear magnetic resonance (13C-NMR) to investigate the transit of organic C through a peatland ecosystem to understand the molecular budget that accompanies the long-term accumulation of C. Samples of biomass, litter, peat soil profile, particulate organic matter, and dissolved organic matter (DOM) were taken from the Moor House National Nature Reserve, a peat-covered catchment in northern England where both the dry matter and C budget for the ecosystem were known. The results showed that: The interpretation of the 13C-NMR spectra shows that polysaccharides are preferentially removed through the ecosystem, while lignin components are preferentially retained and come to dominate the organic matter accumulated at depth in the profile. The DOM is derived from the oxidation of both biomass and the degradation of lignin, while the particulate organic matter is derived from erosion of the peat profile. The DOM is differentiated by its proportion of oxidized functional groups and not by its aromatic content. The changes in functionality leading to DOM production suggest side chain oxidation resulting in C-C cleavage/depolymerisation of lignin, a common reaction within white rot fungi. The 13C-NMR budget shows that O-alkyl functional groups are disproportionately lost between primary production and accumulation in the deep peat, while C-alkyl functional groups are disproportionately preserved. The carbon lost as gases (CO2 and CH4) was estimated to be composed of 93% polysaccharide-derived carbon and 7% lignin-derived carbon.

This study used thermogravimetric analysis (TGA) to study the transit of organic C through a peatland ecosystem. The biomass, litter, peat soil profile, particulate organic matter (POM), and dissolved organic matter (DOM) fluxes were sampled from the Moor House National Nature Reserve, a peat-covered catchment in northern England where both the dry matter and carbon budget for the catchment were known. The study showed that although TGA traces showed distinct differences between organic matter reservoirs and fluxes, the traces could not readily be associated with particular functionalities or elemental properties. The TGA trace shows that polysaccharides are preferentially removed by humification and degradation with residual peat being dominated by lignin compositions. The DOM is derived from the degradation of lignin while the POM is derived from erosion of the peat profile. The carbon lost as gases (CO2 and CH4) was estimated to be composed of 92 to 95% polysaccharide carbon. The composition of the organic matter lost from the peat ecosystem means that the oxidative ratio (OR) of the ecosystem experienced by the atmosphere was between 0.96 and 0.99: currently, the Intergovernmental Panel on Climate Change uses an OR value of 1.1 for all ecosystems.

Although many studies have considered the carbon or greenhouse gas budgets of peat ecosystems, only a few have considered the nutrient budget of peat soils, and this, in turn, has limited the ability of studies to consider the impact of changes in climate and atmospheric deposition on the phosphorus budget of a peat soil. This study considered the total phosphorus (P) budget of an upland peat-covered catchment over the period 1993 to 2012. The study has shown (i) total atmospheric deposition of phosphorus varied from 62 to 175 kg P/km2/yr; (ii) the carbon:phosphorus ratio of the peat profile declines significantly from values in the litter layer (C:P = 1326) to approximately constant at 30 cm depth (C:P = 4240); (iii) the total fluvial flux of phosphorus varied from 49 to 111 kg P/km2/yr, of which between 45 and 77% was dissolved P; and (iv) the total phosphorus sink varied from −5.6 to +71.7 kg P/km2/yr with a median of +29.4 kg P/km2/yr, which is within the range of the estimated long-term accumulation rate of phosphorus in the peat profile of between 3 and 32 kg P/km2/yr. The phosphorus budget of the peat ecosystem relies on rapid recycling near the soil surface, and this means that any vegetation management may critically deprive the ecosystem of this nutrient.