Dinosterol δD values in stratified tropical lakes (Cameroon) are affected by eutrophication

作者: Valérie F. Schwab , Yannick Garcin , Dirk Sachse , Gilbert Todou , Olivier Séné

DOI: 10.1016/J.ORGGEOCHEM.2015.08.003

关键词: Trophic levelSedimentary depositional environmentEnvironmental sciencePlanktonEutrophicationEnvironmental chemistryAutotrophSedimentDinosterolHydrologyHeterotroph

摘要: Abstract In freshwater settings, dinosterol (4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol) is produced primarily by dinoflagellates, which encompass various species including autotrophs, mixotrophs and heterotrophs. Due to its source specificity occurrence in lake marine sediments, presence hydrogen isotopic composition (δD) should be valuable proxies for paleohydrological reconstruction. However, because the purity required isotope measurements difficult achieve using standard wet chemical purification methods, their potential as a proxy rarely exploited. this study, we tested δD values of both particulate organic matter (POM) sediments stratified tropical lakes (from Cameroon) proxy, being characterized variable degrees eutrophication. POM sediment samples, correlated with water values, confirming first order influence values. observed that sedimentary was D enriched from ca. 19 54‰ compared dinosterol. The enrichment column conditions, mainly redox at oxic–anoxic interface (Eh OAI). observations suggest paleohydrologic reconstruction ought sensitive depositional environment, addition more positive potentially reflecting increasing Furthermore, concentration partially reduced vs. non-reduced C34 botryococcenes, stanols stenols, bacterial (diploptene, diplopterol ββ-bishomohopanol) planktonic/terrestrial lipids (cholesterol, campesterol dinosterol) Eh OAI. We such molecular conditions combination evaluate effect trophic status on basis accurately reconstructing

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