The role of post UK-LGM erosion processes in the long-term storage of buried organic C across Great Britain – A ‘first order' assessment

Abstract

Increasing consideration is being given as to whether and how the subsoil can be utilised as a resource to store greater quantities of organic carbon through a range of ‘frontier' technologies. However, recent work suggests ‘priming’ effects may occur when fresh soil organic carbon (SOC) is mixed with older organic carbon (OC). Combined with increasing intensity of land use and perturbation of the surface environment there is potential for buried organic carbon (OC) to be re-incorporated into the active global C cycle. Therefore, understanding the nature of existing buried organic carbon (OC) within Soil Parent Material (SPM) and landscapes is increasingly important. A major OC burial route within landscapes is via erosion and deposition processes. This paper aims to provide a ‘first order' overview of the role erosion processes have made since the UK Last Glacial Maximum (UK-LGM) in the burial of OC in Great Britain. Using collated information, Monte-Carlo simulations were used to produce ‘first-order' estimates of the mass of OC buried within three deposit types; Devensian Till, Devensian Glacio-fluvial deposits and Holocene Alluvium. Combined median estimates for these three deposit types alone suggest, that 385 MT of OC has been buried in these deposits across Great Britain, demonstrating the importance of post UK-LGM erosion processes in long-term sequestration of OC. The paper provides a basis of a framework to describe where buried OC may be found within UK SPM and landscapes, whilst identifying gaps in our knowledge base. Whilst focusing on Great Britain, the processes are relevant to many countries, each of which will have experienced erosion processes unique to their own history of geology, geomorphology and climate.