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Interpretation and application of carbon isotope ratios in freshwater diatom silica
Author(s) -
Webb Megan,
Barker Philip A.,
Wynn Peter M.,
Heiri Oliver,
van Hardenbroek Maarten,
Pick Frances,
Russell James M.,
Stott Andy W.,
Leng Melanie J.
Publication year - 2016
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.2837
Subject(s) - authigenic , diatom , carbon cycle , dissolved organic carbon , isotopes of carbon , geology , biogenic silica , total inorganic carbon , environmental science , sediment , drainage basin , hydrology (agriculture) , biogeochemical cycle , oceanography , total organic carbon , ecology , ecosystem , geomorphology , carbon dioxide , geography , biology , cartography , geotechnical engineering
Carbon incorporated into diatom frustule walls is protected from degradation enabling analysis for carbon isotope composition (δ 13 C diatom ). 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 δ 13 C diatom . Here relationships between water chemistry and δ 13 C diatom 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 δ 13 C diatom , with a greater impact than productivity. Application of these principles was made to a sediment record from Lake Tanganyika. δ 13 C diatom co‐varied with δ 13 C bulk through the last glacial and Holocene. This suggests carbon supply was again dominant and exceeded authigenic demand. This first systematic evaluation of contemporary δ 13 C diatom controls demonstrates that diatoms have the potential to supply a record of carbon cycling through lake catchments from sediment records over millennial timescales.