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Leaf wax n-alkanes
Abstract:
Abstract The Mediterranean Peninsula increasingly suffers from droughts and aridity, the first consequences of global climate change in that region. Precise scenarios for the region's future climate predictions require knowledge about the processes of past climate changes, but information about the Western Mediterranean climate and its history is controversial. For this study, we applied compound-specific δ13C and δ2H analyses on long-chain n-alkanes in the ~8 m El Paraíso loess-paleosoil sequence (LPS), Central Spain, to investigate climate and environmental changes during the Late Quaternary. The δ13C values are most enriched during marine isotope stage (MIS) 3, indicating more arid conditions, while lower values during \MIS\} 4 and 2 are interpreted to document more humid conditions. Low values are also recorded for the Holocene colluvium, which can at least partly be explained with higher concentrations in atmospheric CO2. The δ2H values are mostly enriched during the last glacial compared to the Holocene. We suggest that this is mainly controlled by isotopic effects related to the moisture source, yet other possible effects like evapotranspirative enrichment and changes in atmospheric circulation patterns shouldn't be ruled out. Our results corroborate previous findings based on leaf wax patterns, geomorphological records, and climate models. They all indicate relatively humid conditions during \{MIS\} 2 compared to more arid phases during \{MIS\ 3.
