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MESL Biogeochemistry and climate-related research

Carbon Isotopes ratios (d 13C) for tracking sources, ocean carbon cycling and climate changes

Schema of d13C distribution
in the environment

The study of biomarker proxies and their isotope composition provides a tool to characterize the organic material. Among these, some lipidic structures are useful in the study of the origin and dynamics of organic matter in the environment. Thus, some lipids are used as tracers of terrestrial organic matter (long-chain n-alkanes, n-alkanols and n-fatty acids), bacterial production (branched fatty acids) or as indicators of marine primary productivity (unsaturated alkenones and dinosterol). The advances in Isotope Ratio Monitoring - Gas Chromatography Mass Spectrometry (IRM-GCMS) provide information about the sources of biomarkers preserved in sedimentary organic matter, based on the carbon isotope compositions of individual components. Due to the differential 13C/12C values, isotopic carbon data is frequently used to analyse the importance of terrestrial plants with different photosynthetic routes (C3, C4 or CAM), to study the terrestrial sources of organic matter in the oceans or to assess the relevance of marine or terrestrial organic compounds in the estuaries.

Within this framework, MESL is measuring 13C/12C isotope ratios in individual organic compounds for:

  • assessing origin of organic matter from land-based and/or marine sources
  • diagnosing and fingerprinting oil contaminant sources
  • investigating cycling and behaviour in the marine environment
  • exploring the stable carbon isotope fractionation of different phytoplankton taxa in relation to different environmental conditions and productivity regimes
  • studying the transfer of 13C-labelled and non-labelled carbon between the environment and the marine organisms to further understand food web interactions, biochemical cycling and ecosystem functioning
  • reconstructing the environmental and climatic conditions, marine productivity, terrigenous input, as well as, to assess basin-wide vegetation and anthropogenic impacts on geological timescales


References:
  • Carbon isotope composition of fatty acids and sterols in the scleractinian coral Turbinaria reniformis: Effect of light and feeding. Limnol Oceanogr. 54: 1933-1940 (2009).
  • Effect of light and feeding on the fatty acid and sterol composition of zooxanthellae and host tissue isolated from the scleractinian coral Turbinaria reniformis. Limnology and oceanography, v. 53, 2702-2710, (2008).
  • Distribution of lipid biomarkers and carbon isotope fractionation in contrasting trophic environments of the South East Pacific. Biogeosciences, v. 5, 949-968, (2008).
  • Distribution of pigments and fatty acid biomarkers in particulate matter from the frontal structure of the Alboran Sea (SW Mediterranean Sea). Marine chemistry, v. 88, 103-125, (2004)
  • Distribution of sterol and fatty alcohol biomarkers in particulate matter from the frontal structure of the Alboran Sea (SW Mediterranean Sea). Marine Chemistry 82, 161-183, (2003).