Sulphur constraints on peatland carbon cycle
Abstract
This study considered the stoichiometry and energy content of organic matter reservoirs and fluxes through and from a peatland. The stoichiometry and energy content were used to constrain the carbon budget of the peatland and the stoichiometric constraints showed that the transition to deep peat was limited by the availability of electron acceptors. The stoichiometry suggests there is insufficient energy available in the organic matter to produce CH4. The alternative pathways need either to use sulphate as a terminal electron acceptor or to use the DOM present in the peat pore water as the energy source. To test these explanations this study considered the sulphur budget of this peatland and the composition of the DOM in the peat profile pore water.
We assess the internal transfer of sulphur from Moor House National Nature Reserve, an upland blanket peat bog in Upper Teasdale, United Kingdom. Samples of above ground vegetation and litter, peat soil cores, and dissolved and particulate organic matter (DOM and POM) from soil pore water and stream water were taken for elemental analysis of sulphur, carbon, hydrogen, nitrogen and oxygen to understand the composition of organic matter and how it changes through the peatland system. We also construct a fluvial sulphur budget from over 20 years of water quality monitoring within the catchment. Results show that sulphur content increases from vegetation to litter and then through the top 25 cm of the peat profile. Sulphur content declined from 25 cm depth in the peat profile, before stabilising from 50 cm depth to the base of the soil core. Sulphur has an average content of 0.56% in soil pore water DOM, compared to 0.89% in stream water DOM. The preliminary fluvial budget indicated a mean input of 13.0 ± 1.4 tonnes SO4/km2/yr across 20 years of precipitation data, while fluvial losses of SO4, dissolved organic sulphur and particulate organic sulphur were on average 89.5 ± 1.5% of the precipitation budget.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B21I2445W
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCESDE: 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCESDE: 1879 Watershed;
- HYDROLOGY