GDGT concentration and stable carbon isotope from Mackenzie Delta lakes

Glycerol Dialkyl Glycerol Tetraethers (GDGTs) have been analyzed from lacustrine sediment cores (3 lakes) in the Mackenzie Delta (Northwestern Territories, Canada). The cores are covering the last 200 years. GDGT have been extracted using EDGE and separated over aluminium oxide column using dichloromethane:methanol (1:1), then filtered. They have been quantified using an internal standard on a HPLC (high precision liquid chromatograph). Their compound-specific 13C ratios have been measured at low resolution (~3 samples per cores) on a SWIM-IRMS (spooling-wire microcombustion device interfaced with an isotope-ratio mass spectrometer). Their values have been compared to 13C of the bulk and 13C of diplopten to assess their sources and the metabolism of their producers.