The stable hydrogen isotope composition of lipid biomarkers, such as alkenones, is a promising new tool for the improvement of palaeosalinity reconstructions. Laboratory studies confirmed the correlation between lipid biomarker dD composition (dDLipid), water dD composition (dDH2O) and salinity; yet there is limited insight into the applicability of this proxy in oceanic environments. To fill this gap, we test the use of the dD composition of alkenones (dDC37) and palmitic acid (dDPA) as salinity proxies using samples of surface suspended material along the distinct salinity gradient induced by the Amazon Plume. Our results indicate a positive correlation between salinity and dDH2O, while the relationship between dDH2O and dDLipid is more complex: dDPAM correlates strongly with dDH2O (r2 = 0.81) and shows a salinity-dependent isotopic fractionation factor. dDC37 only correlates with dDH2O in a small number (n = 8) of samples with alkenone concentrations 〉 10 ng L**-1, while there is no correlation if all samples are taken into account. These findings are mirrored by alkenone-based temperature reconstructions, which are inaccurate for samples with low alkenone concentrations. Deviations in dDC37 and temperature are likely to be caused by limited haptophyte algae growth due to low salinity and light limitation imposed by...
Event Label ; Latitude Of Event ; Longitude Of Event ; Depth, Water ; Sea Surface Temperature ; Sea Surface Temperature, Standard Deviation ; Sea Surface Salinity ; Standard Deviation ; Alkenone, C37 ; Hexadecanoic Acid ; Alkenone, Unsaturation Index Uk'37 ; Alkenone C37/C38 Ratio ; Comment ; Delta Deuterium, Water ; Delta Deuterium, Standard Deviation ; Delta Deuterium, Alkenone, C37 ; Error ; Delta Deuterium, Palmitic Acid ; Measured ; Mass Spectrometer Finnigan Mat 253 ; Msm20/3 ; Maria S. Merian ; Center For Marine Environmental Sciences (Marum)
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