Mechanisms controlling the carbon stable isotope composition of phytoplankton in karst reservoirs

  • Baoli Wang | baoliwang@163.com State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, China.
  • Cong-Qiang Liu State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, China.
  • Xi Peng State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences; Graduate University of Chinese Academy of Sciences, China.
  • Fushun Wang Institute of Applied Radiation, School of Environmental and Chemical Engineering, Shanghai University, China.

Abstract

In order to systematically understand the mechanisms controlling the carbon stable isotope composition of phytoplankton (δ13CPHY)in freshwater ecosystems, seasonal changes in δ13CPHY and related environmental factors were determined in karst reservoirs from the Wujiang river basin, China. Substantial and systematic differences within seasons and reservoirs were observed for δ13CPHY, which ranged from -39.2‰ to -15.1‰. An increase in water temperature triggered fast growth of phytoplankton which assimilated more dissolved inorganic carbon (DIC), resulting in the increase of δ13CPHY, δ13CDIC and pH. When the concentration of dissolved carbon dioxide (CO2) was less than 10 mmol L–1, phytoplankton shifted to using HCO3– as a carbon source. This resulted in the sharp increase of δ13CPHY. The carbon stable isotope composition of phytoplankton tended to decrease with the increase of Bacillariophyta, which dominated in January and April, but tended to increase with the increase of Chlorophyta and Dinophyta, which dominated in July. Multiple regression equations suggested that the influence of biological factors such as taxonomic difference on δ13CPHY could be equal or more important than that of physical and chemical factors. Thus, the effect of taxonomic differences on δ13CPHY must be considered when explaining the δ13C of organic matter in lacustrine ecosystem.

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Published
2013-02-06
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Original Articles
Keywords:
δ13C, temperature, taxonomic difference, phytoplankton, karst reservoir
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How to Cite
1.
Wang B, Liu C-Q, Peng X, Wang F. Mechanisms controlling the carbon stable isotope composition of phytoplankton in karst reservoirs. J Limnol [Internet]. 2013Feb.6 [cited 2021May7];72(1):e11. Available from: https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2013.e11