Testing the use of biomarkers to trace organic carbon in a small rural catchment in the U.K

Abstract

rham University MRes thesis
Kathryn Ruth Melvin
Abstract
Testing the use of biomarkers to trace organic carbon in a small rural catchment in the U.K
The interaction between climate change and the carbon cycle on land is a pressing topic that is frequently discussed within both academia and government. Extensive research has been undertaken into organic carbon export in forested river systems, including estimating the organic carbon (OC) fluxes transported towards, and deposited in, the ocean. However, the origins of carbon transported by smaller, anthropogenically-modified river systems that are widespread in the UK are more poorly constrained. A novel approach to trace the source and pathway of OC is to use biomarkers – identifiable organic compounds that can be linked to the biological processes that formed them. This approach has been widely applied to reconstruct past environmental change and climate, but has recently been recognised as having promise to trace OC transport in rivers. In this thesis, the biomarker method was applied to a small river catchment to explore if this analysis could better constrain the origins, types and transfer of OC, furthering knowledge of the importance of catchment and fluvial process in a wider context. This thesis focuses on the River Esk in the North York Moors. The River Esk has been studied extensively because of the geology and the varied land use, from peatlands to agricultural and small forest areas, so that this catchment provides varied land uses and has the potential input of distinct OC sources which can be identified using the biomarker method. River sediments collected using a time-integrated sampling method were used to explore spatial patterns. Further work and the inclusion of more seasonal data would add even more information that is missing in this area of study. It was concluded that the use of biomarkers gave additional information when trying to understand river processes. All sample sites using biomarker analysis gave data consistent with what would be typically expected for the surroundings. An interesting difference was observed in two of the sample sites, where the biomarkers indicated an aged fossil signal. A human influence was confirmed as both sites were major sites in the iron industry in the 1800s.