Change search
ReferencesLink to record
Permanent link

Direct link
Tracing late Holocene changes in lake-water total organic carbon: A multi-proxy approach based on sediment bio-geochemistry and a faecal biomarker
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. (Paleolimnologi)
2015 (English)Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
Abstract [en]

Long-term dynamics of lake-water total organic carbon (LW-TOC) concentrations in freshwater lakes provide an important perspective on the recent increases in LW-TOC observed in many of these systems and may assist with the identification of natural and anthropogenic drivers of change. This study examines how LW-TOC in Dragsjön, a lake situated in an area with a long history of anthropogenic land use, has changed in response to natural and anthropogenic perturbations throughout the Holocene. To provide a better understanding of the processes involved, a multi-proxy study was conducted and included multi-element geochemistry (17 major and trace elements), biogenic silica, organic matter (OM) content and composition, and the faecal biomarker “coprostanol”. The direct biomarker for anthropogenic presence, “coprostanol”, and a detailed characterisation of OM composition are for the first time applied for tracing changes in LW-TOC. Natural processes contributed to stable LW-TOC concentrations in Dragsjön for most part of the Holocene. Humans were present in the catchment from AD 100 as indicated by coprostanol, but did not begin to affect LW-TOC until c. AD 1500. In the last 500 years LW-TOC steadily declined from 17 to 10 mg L-1 in response to anthropogenic alterations to the terrestrial biomass balance. The increase in LW-TOC during the last 70 years likely represents a recovery from anthropogenic disturbance rather than a baseline shift in response to any of the number of proposed recent stressors. The faecal biomarker coprostanol and OM composition provided information essential for identifying and characterising the effects of anthropogenic disturbance.

Place, publisher, year, edition, pages
2015. , 39 p.
Keyword [en]
lake-water TOC, faecal biomarkers, Pyrolysis GC/MS, forest grazing
National Category
Other Earth and Related Environmental Sciences
URN: urn:nbn:se:umu:diva-105596OAI: diva2:826865
Subject / course
Examensarbete i Geovetenskap/naturgeografi avseende masterexamen
Educational program
Master's Programme in Geoecology
Available from: 2015-06-26 Created: 2015-06-25 Last updated: 2015-06-26Bibliographically approved

Open Access in DiVA

fulltext(2013 kB)104 downloads
File information
File name FULLTEXT01.pdfFile size 2013 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
Department of Ecology and Environmental Sciences
Other Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 104 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 225 hits
ReferencesLink to record
Permanent link

Direct link