Personnel: Pippa Chapman, Simon Bottrell, Joanna Clark, Rob Newton and Rebecca Bartlett (EBI, University of Leeds), Chris Evans (Centre for Ecology and Hydrolgy) and Don Monteith (UCL)
Project period: 3 years from March 2006
Figure 1: River water enriched in dissolved organic carbon during a storm event
Dissolved organic carbon (DOC) is turning our upland rivers and lakes darker (Figure 1). But they may be returning to pre-industrial states rather than suffering from climate change as some think, according to researchers from the University of Leeds, Centre for Ecology & Hydrology (CEH) and University College London. Since 1988, levels of DOC in UK upland waters (represented by the UK Acid Waters Monitoring Network) have risen 91 percent on average (Figure 2), and similar changes are occurring in parts of Scandinavia and North America. Some blame climate change, predicting peatlands will begin releasing vast quantities of climate-changing carbon. But this may be overly pessimistic. Recent analysis of available monitoring and experimental data undertaken by the research team suggest the biggest consistent factor affecting these ecosystems is reduced acid rain (Evans et al., 2006). Less acidic soils allow more of the DOC produced by plants and soils to leach into streams and lakes. Rising temperatures, increased droughts and rising plant productivity could all contribute, but we suspect they're not the main cause. Not everyone agrees, and there's a lively ongoing debate. So this spring, research funded by the Natural Environment Research Council (NERC) started at the University of Leeds to test the researchers’ ideas. The team will experiment with soil from polluted and unpolluted sites across the UK, to examine how changing acidity and temperature affect DOC release. This research should help predict changes in the peatland carbon cycle, and in the ecology of upland waters.
Figure 2: Box and whisker plots summarising DOC concentrations in samples of river and lake water collected from all 22 AWMN sites