Assessing the impact of catchment management and climatic change on dissolved organic carbon flux in relation to drinking water treatment.

Jonathan Ritson1, Graham Nigel1, Templeton Michael1, Freeman Chris2, Clark Joanna3
1 Civil and Environmental Engineering, Imperial College London
2 Wolfson Carbon Capture Laboratory, School of Biological Sciences, Bangor University
3 Walker Institute for Climate Systems Research and Soil Research Centre, Geography and Environmental Science, School of Human and Environmental Sciences, University of Reading

P 7.16 in Controls of dissolved organic matter fluxes in ecosystems

Poster Session 1 on Monday, 16:30-18:30

Current restoration programmes in the UK and internationally seek to raise peatland water tables and support the prevalence of Sphagnum Spp., however vascular species may become more dominant under future climate change projections. How these two drivers will effect dissolved organic carbon (DOC) flux and the treatment of surface waters for potable water is currently unclear. We collected samples of typical UK upland vegetation (Calluna vulgaris, Sphagnum spp., Molinia caerulea) and samples of peat collected from depths of 0-5 cm and 5-10 cm from beneath stands of Sphagnum spp. and Molinia caerulea in Exmoor National Park, UK. DOC leachate was extracted from the vegetation, producing significantly different (Kruskall-Wallace p=0.025) amounts of DOC with Molinia caerulea producing the most (4.86 ±0.56 mg/g dry weight) and Sphagnum spp. the least (2.46 ±0.29 mg/g dry weight). The DOC leachate also had different specific ultraviolet absorption at 254nm (SUVA) (Kruskall-Wallace p=0.005) however this did not correspond to differences in removal efficiency by coagulation/flocculation with ferric sulphate (Kruskall-Wallace p=0.399). This would suggest that shifts in dominant vegetation from Sphagnum spp. to vascular species will increase DOC concentrations in surface waters but that scale-up or optimisation of current treatment practices may be capable of dealing with this. No significant differences were found between peat from beneath different vegetative sources (Kruskall-Wallace p=0.248) or from different depths (Kruskall-Wallace p=0.094), suggesting that changes in dominant vegetation will not affect the quantity or quality of DOC released from peat, only that from fresh litter and vegetation. These results lend technical justification to current programmes to support Sphagnum spp. for water quality purposes and point to the importance of changes in litter input as a control on DOC flux.

last modified 2014-04-03