, Volume 109, Issue 1–3, pp 253–270 | Cite as

Processes controlling DOC in pore water during simulated drought cycles in six different UK peats

  • J. M. Clark
  • A. Heinemeyer
  • P. Martin
  • S. H. Bottrell


The effect of episodic drought on dissolved organic carbon (DOC) dynamics in peatlands has been the subject of considerable debate, as decomposition and DOC production is thought to increase under aerobic conditions, yet decreased DOC concentrations have been observed during drought periods. Decreased DOC solubility due to drought-induced acidification driven by sulphur (S) redox reactions has been proposed as a causal mechanism; however evidence is based on a limited number of studies carried out at a few sites. To test this hypothesis on a range of different peats, we carried out controlled drought simulation experiments on peat cores collected from six sites across Great Britain. Our data show a concurrent increase in sulphate (SO4) and a decrease in DOC across all sites during simulated water table draw-down, although the magnitude of the relationship between SO4 and DOC differed between sites. Instead, we found a consistent relationship across all sites between DOC decrease and acidification measured by the pore water acid neutralising capacity (ANC). ANC provided a more consistent measure of drought-induced acidification than SO4 alone because it accounts for differences in base cation and acid anions concentrations between sites. Rewetting resulted in rapid DOC increases without a concurrent increase in soil respiration, suggesting DOC changes were primarily controlled by soil acidity not soil biota. These results highlight the need for an integrated analysis of hydrologically driven chemical and biological processes in peatlands to improve our understanding and ability to predict the interaction between atmospheric pollution and changing climatic conditions from plot to regional and global scales.


Dissolved organic carbon DOC Sulphate Drought Episodic acidification Peat Climate change 



This research was supported by the School of Geography, University of Leeds Research Development Fund and Natural Environment Research Council (NERC) (NE/D00599X/1). J.M. Clark was also supported by a fellowship from the Grantham Institute for Climate Change, Imperial College. A. Heinemeyer was funded through a NERC grant (F14/G6/105) as part of the Centre for Terrestrial Carbon Dynamics. We thank The Applecross Estate, Scottish Natural Heritage, Forestry Commission, Natural England, Jeff Dowey and Simon Bennett-Evans for access to the field sites; Ron Smith (CEH Edinburgh) for providing deposition estimates; Miles Ratcliffe, David Ashley and Rachel Gasior for assistance with the soil analysis; David Cooper and Vicky Bell (CEH) for help calculating baseline climatic data; UK Meteorological Office. MIDAS Land Surface Stations data (1853-current), [Internet]. British Atmospheric Data Centre, 2006, 2010. Available from We also thank two anonymous referees and the editors for their comments which have helped to improve the manuscript.


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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • J. M. Clark
    • 1
    • 2
    • 3
  • A. Heinemeyer
    • 4
  • P. Martin
    • 5
    • 6
  • S. H. Bottrell
    • 2
  1. 1.Soil Research Centre, Department of Geography and Environmental Science, School of Human and Environmental SciencesUniversity of ReadingReadingUK
  2. 2.School of Earth and Environment and School of GeographyUniversity of LeedsLeedsUK
  3. 3.Grantham Institute for Climate Change Fellow, Civil and Environmental EngineeringImperial College LondonLondonUK
  4. 4.Stockholm Environment Institute at the Environment Department and Centre for Terrestrial Carbon Dynamics (York-Centre)University of YorkYorkUK
  5. 5.Department of BiologyUniversity of YorkYorkUK
  6. 6.National Oceanography Centre, SouthamptonSouthamptonUK

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