Transfer of organic matter through a peatland system – from terrestrial to aquatic systems

Peatlands are important terrestrial carbon stores and it is important to understand the processes involved in carbon cycling. At Moor House, an upland blanket bog in the United Kingdom (UK), stoichiometric approaches have been adopted to understand carbon cycling through the peatland and this has been used to understand the production, transport and transformation of organic matter from terrestrial to aquatic systems.

Previous results analysing vegetation, peat cores, soil pore water from shallow and deep sample depths, and stream water from Moor House assessed how the composition of organic matter changes through the peatland system, to its export in the stream network. Results showed that there was an increase in the nominal carbon oxidation state (C_ox) of dissolved organic matter (DOM) transferred from soil pore water to stream water. The composition of DOM in soil pore water evolved from near-surface peat layers but stream water DOM was quite distinct in composition. This study assessed the role of DOM in the degradation of peat organic matter by examining the composition of DOM through the peat profile and in separate flow pathways. Sampling was undertaken at Moor House, with sampling from surface, shallow and deep soil water; surface runoff and stream water. Samples were analysed for their elemental content (C, H, N and O), and differential scanning calorimetry and bomb calorimetry.