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Erik Jeppesen

Geochemical records of anoxic water mass expansion in an oligotrophic alpine lake (Yunnan Province, SW China) in response to climate warming since the 1980s

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DOI

  • Yongdong Zhang, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences
  • ,
  • Yaling Su, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences
  • ,
  • Zhengwen Liu, Jinan University
  • ,
  • Erik Jeppesen
  • Jinlei Yu, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences
  • ,
  • Miao Jin, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences

In order to elucidate the effect of recent warming, we studied lipid biomarkers and trace elements in a dated sediment core from Lake Heihai, a small, deep, and ultraoligotrophic alpine lake in Yunnan Province (SW China), being only marginally affected by anthropogenic activities. The variation in lipid biomarkers (such as 10-methyl-C16:0 fatty acid (FA), iso-branched C15 (i-C15) and anteiso-branched C15 (ai-C15) FA, and tetrahymanol) suggests a rapid productivity increase in sulfate reducing bacteria and ciliates since 1980, likely reflecting expansion of the hypolimnion anoxia and a prolonged duration of an oxic–anoxic chemocline in the water column. The concentrations of element molybdenum (Mo) in pre-1980 sediments approach the values in average crust. After 1980, the concentration increased, reaching levels approximately sixfold higher than the initial abundances. This likely reflects a high authigenic Mo deposition when the bottom water was more anoxic and enrichment in H2S. The suggested spatial and temporal expansion of the anoxic bottom water since 1980 was probably a response to the regional climate warming, resulting in stronger water column stratification and terrestrial grass inputs to the lake, and thus higher dissolved oxygen (DO) loss in hypolimnion.

Original languageEnglish
JournalThe Holocene
Volume26
Issue11
Pages (from-to)1847-1857
Number of pages11
ISSN0959-6836
DOIs
Publication statusPublished - 1 Nov 2016

    Research areas

  • biomarker, climate warming, dissolved oxygen, Lake Heihai, molybdenum, sediment

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