Carbon isotopes of n-alkanoic acids in Antarctic ornithogenic sediments as indicators of sedimentary lipid sources and paleocological change

• Published in: The Science of the total environment Vol. 709; p. 135926
• Main Authors: Chen, Xin, Wei, Yangyang, Nie, Yaguang, Wang, Jianjun, Emslie, Steven D., Liu, Xiaodong
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.03.2020
• Subjects: Animals; Antarctic Regions; Antarctica; Carbon; Carbon isotope ratios; Carbon Isotopes; Geologic Sediments; Lipids - chemistry; n-alkanoic acids; Nitrogen Isotopes; Ornithogenic sediments; Penguin population change; Seals, Earless; Spheniscidae; Antarctic Regions; Ornithogenic sediments; Penguin population change; Antarctica; Carbon isotope ratios; n-alkanoic acids
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.135926

Sedimentary n-alkanoic acids are ubiquitous in the environment and their carbon isotopic composition is increasingly used to identify the source of organic matter and to reconstruct past climatic and ecological changes. Here we investigate the distribution and carbon isotope ratios of n-alkanoic acids in two sediment profiles influenced by animal excrement in Antarctica. We found that organic matter input from animal excrement is the predominate source of short- and mid-chain n-alkanoic acids in the ornithogenic sediments. Decreased δ13C values are closely related to increased excrement input of penguins and seals that occupied the study site, especially in C16n-alkanoic acid. Long-chain (>C24) n-alkanoic acids likely originate from moss and heterotrophic microbes, and the δ13C values of C26n-alkanoic acid were consistent with organic biomarkers and bio-elements from animal excrement. Two possible processes are suggested to explain the close relationship between C26n-alkanoic acid δ13C values and animal excrement input. All the results indicate that the carbon isotopes of n-alkanoic acids in ornithogenic sediments can be used to indicate historical population change of penguins or seals in Antarctica. [Display omitted] •Long-chain n-alkanoic acids are abundant in Antarctic ornithogenic sediments.•These long-chain compounds derive from moss and heterotrophic microbes.•The δ13C of n-alkanoic acids has the potential to indicate historical change of penguin and seal.•The δ13C values of C16 and C26n-alkanoic acids are the strongest response to animal excrement input.