Fractionation of hydrogen,oxygen and carbon isotopes in n-alkanes and cellulose of three Sphagnum species |
| |
| Institution: | 1. IGB Leibniz Institute of Freshwater Ecology and Inland Fisheries Berlin, Berlin, Germany;2. Humboldt University Berlin, Berlin, Germany;3. Northern Rivers Institute, School of Geosciences, University of Aberdeen, United Kingdom;1. State key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;2. CAS Key Laboratory of Ocean and Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China |
| |
| Abstract: | Compound-specific isotope measurements of organic compounds are increasingly important in palaeoclimate reconstruction. Searching for more accurate peat-based palaeoenvironmental proxies, compound-specific fractionation of stable C, H and O isotopes of organic compounds synthesized by Sphagnum were determined in a greenhouse study. Three Sphagnum species were grown under controlled climate conditions. Stable isotope ratios of cellulose, bulk organic matter (OM) and C21–C25 n-alkanes were measured to explore whether fractionation in Sphagnum is species-specific, as a result of either environmental conditions or genetic variation. The oxygen isotopic composition (δ18O) of cellulose was equal for all species and all treatments. The hydrogen isotopic composition (δD) of the n-alkanes displayed an unexpected variation among the species, with values between ?154‰ for Sphagnum rubellum and ?184‰ for Sphagnum fallax for the C23 n-alkane, irrespective of groundwater level. The stable carbon isotopic composition (δ13C) of the latter also showed a species-specific pattern. The pattern was similar for the carbon isotope fractionation of bulk OM, although the C23 n-alkane was >10‰ more depleted than the bulk OM. The variation in H fractionation may originate in the lipid biosynthesis, whereas C fractionation is also related to humidity conditions. Our findings clearly emphasize the importance of species identification in palaeoclimate studies based on stable isotopes from peat cores. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
