The role of pipes in carbon export from peatlands

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Since the end of the last ice age large amounts of atmospheric carbon dioxide have been slowly locked up in peat soils in the cool, wet, northern regions of the world as partially decomposed plant remains. If this huge reservoir of carbon was to be released back in to the atmosphere it would cause a significant rise in carbon dioxide and release methane and result in further global warming. At the moment scientists are trying to unravel the mechanisms that control the losses and gains of carbon from this large area of the Earth's surface. Peat soils, which can be up to 5 m or more in thickness, consist of about 90 % water and are important resources for the companies that supply water to homes in the UK. Although it has been known that peat soils contain large numbers of 'pipes' (naturally occurring sub-surface tubes or voids of various lengths and sizes), it has recently been shown that they occur in extremely large numbers in many UK peatlands. Pipe development may also be encouraged by the drainage of peat bogs and also by periods of summer drought such as those which occurred in 1976 and 1995 in northern Europe. Since much of our understanding about water movement in peats tends to exclude the role of pipes, it is important to investigate the role that they play in delivering water and carbon (in various dissolved and gaseous forms and as small water-borne particles) to streams. Peat pipes could provide an important route to connect the large reservoir of carbon stored in peats to peatland pools and streams, and may act as pathways along which carbon can leak away. We aim to investigate how pipes control the loss of water and carbon from peatlands. Most of the research work, which will take three years to complete and involves collaboration between scientists in Leeds, London and Edinburgh, will be carried out at Moor House in the north Pennines, UK in a catchment that has been designated a carbon study catchment by the Centre for Ecology and Hydrology. Our work will involve measuring the concentrations and amounts of carbon and water flowing in pipes and streams. We will use techniques that allow us to determine the age of the carbon being released and therefore where in the peat the carbon is coming from. The overall aim of our work is to help scientists to understand more about the natural processes which affect this important global store of carbon.