Biogeochemistry

, Volume 109, Issue 1, pp 253–270

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
Article

DOI: 10.1007/s10533-011-9624-9

Cite this article as:
Clark, J.M., Heinemeyer, A., Martin, P. et al. Biogeochemistry (2012) 109: 253. doi:10.1007/s10533-011-9624-9

Abstract

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.

Keywords

Dissolved organic carbon DOC Sulphate Drought Episodic acidification Peat Climate change 

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