Dynamics and Biogeochemistry of River Corridors and Wetlands (Proceedings of symposium S4 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 294, 2005, 3-9

1 School of Geography, University of Leeds, Leeds LS2 9JT, UK

2 Centre for Sustainable Water Management, The Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK

3 Centre for Ecology and Hydrology, The Lancaster Environment Centre, Lancaster LA1 4AP, UK

4 Department of Geography, University of Durham, Durham DH1 3LE, UK

Abstract The dynamics of dissolved organic carbon (DOC) in blanket peat soil solution has been monitored at an upland catchment in northern Britain in relation to key environmental controls. Dissolved organic carbon (DOC) displayed a strong seasonal cycle that showed a clear relationship with soil temperature. However, in years of significant water table drawdown (>25 cm), summer DOC concentrations were substantially lower than in "normal" years, suggesting that factors other than temperature controlled the release of DOC. Major episodic release of sulphate (SO₄^2-), and an associated decline in pH, was also observed during drought periods. Controlled laboratory experiments were conducted over a 22 week period to factor out the relationships between water table depth, temperature and soil solution chemistry on DOC dynamics. The results from the laboratory experiments closely followed the patterns observed in the field data. Results suggest that changes in soil solution chemistry (especially SO₄^2-), in response to changes in soil hydrology, exerted a stronger control on DOC dynamics under drought conditions than variations in temperature alone.