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School of Geography

River Basin Processes and Management Projects

Greenhouse gas emissions associated with non-gaseous losses of carbon from peatlands - fate of particulate and dissolved carbon

PI: Sheila Palmer

Co-I: Pippa Chapman, Joseph Holden 

Overview: Peatlands hold the UK's largest single store of carbon. In good condition, they can contribute to attempts to offset climate change due to fossil fuel burning, steadily drawing down CO2 from the atmosphere and storing it securely over millennia. On the other hand, if they are destabilised by poor land-management, pollution, warming or drying, they can release CO2 back to the atmosphere, exacerbating climate change. In addition, peatlands 'leak' some of the carbon they hold into the rivers that drain them, as dissolved organic carbon (DOC), particulate organic carbon (POC) and inorganic carbon (IC). Although this riverine loss occurs from all peatland systems (it is the DOC which gives peaty rivers their characteristic brown colour), the amount of carbon released can increase if peatlands become unstable, for example through the gully erosion seen in areas such as the Peak District.

At present, we do not know where all the carbon transported from peatlands into rivers goes. If it is passively transported down rivers and back into sediments in lakes, reservoirs or coastal waters, this relocation of carbon from one secure store to another will not affect the climate. If, on the other hand, it is actively processed in the river system, and decomposed to CO2 or to the more powerful greenhouse gas methane, this will contribute to global warming. By establishing how much of the total river carbon flux is converted into greenhouse gases, we hope to be able to complete our understanding of the greenhouse gas balance of peatlands. We will then be better able to manage the UK's peatlands so that they can make a positive contribution to global climate by helping to lock up greenhouse gases.

To determine the fate of the riverine carbon released from peatlands, we will study how the different forms of river carbon are processed at a range of critical locations within river systems. These range from small headwater streams, lakes and reservoirs, the confluences between streams draining peatlands and other streams with different chemistry, down to the estuary. We will also consider the role of drinking water treatment works where this carbon is removed by a variety of methods. The approaches used will combine a programme of laboratory experiments designed to identify  the processes which  remove DOC, POC and IC from the water, where and how fast they occur, with a parallel programme of field-based experiments and measurements at a range of peatland sites across England and Wales. Ultimately, we hope to be able to determine what proportion of each of these forms of carbon is ultimately emitted to the atmosphere as greenhouse gases, and to identify methods of managing the land, or water supply systems, which could help to reduce these emissions.

Start date: 01 September 2010

End date: 31 August 2013

Funder: Department for Environment, Food and Rural Affairs (Defra)