Interpretation and application of carbon isotope ratios in freshwater diatom silica

Webb, Megan and Barker, Philip A. and Wynn, Peter M. and Heiri, Oliver and van Hardenbroek, Maarten and Pick, Frances and Russell, James M. and Stott, Andy W. and Leng, Melanie J. (2016) Interpretation and application of carbon isotope ratios in freshwater diatom silica. Journal of Quaternary Science, 31 (4). pp. 300-309. ISSN 1099-1417

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Carbon incorporated into diatom frustule walls is protected from degradation enabling analysis for carbon isotope composition (δ13Cdiatom). This presents potential for tracing carbon cycles via a single photosynthetic host with well-constrained ecophysiology. Improved understanding of environmental processes controlling carbon delivery and assimilation is essential to interpret changes in freshwater δ13Cdiatom. Here relationships between water chemistry and δ13Cdiatom from contemporary regional data sets are investigated. Modern diatom and water samples were collected from river catchments within England and lake sediments from across Europe. The data suggest dissolved, biogenically produced carbon supplied proportionately to catchment productivity was critical in the rivers and soft water lakes. However, dissolved carbon from calcareous geology overwhelmed the carbon signature in hard water catchments. Both results demonstrate carbon source characteristics were the most important control on δ13Cdiatom, with a greater impact than productivity. Application of these principles was made to a sediment record from Lake Tanganyika. δ13Cdiatom co-varied with δ13Cbulk through the last glacial and Holocene. This suggests carbon supply was again dominant and exceeded authigenic demand. This first systematic evaluation of contemporary δ13Cdiatom controls demonstrates that diatoms have the potential to supply a record of carbon cycling through lake catchments from sediment records over millennial timescales.

Item Type: Article
Keywords: carbon cycling; diatom frustule carbon; Lake Tanganyika; palaeoclimate; stable carbon isotopes
Schools/Departments: University of Nottingham UK Campus > Faculty of Social Sciences > School of Geography
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Depositing User: Eprints, Support
Date Deposited: 30 Jun 2016 08:58
Last Modified: 14 Sep 2016 02:02

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