Branched glycerol dialkyl glycerol tetraethers (brGDGTs) from lake sediments in Alaska, Yukon, and Northwest Territories ...

• Main Authors: Porter, Trevor, Otininao, Gerard, Bergman, Matthew, Buceta, Rhys, Phillips, Michael
• Format: Dataset
• Language: English
• Published: Canadian Cryospheric Information Network 2022
• Subjects: Northwest Territories; Alaska; Yukon
• Online Access: https://dx.doi.org/10.21963/13282; https://www.polardata.ca/pdcsearch?doi_id=13282

The brGDGTs used in this study derive from the shallow sediments of 43 lakes in Alaska, Yukon, and Northwest Territories across a latitudinal gradient of 59.5 to 69.4 °N and elevations of 2 to 1187 masl in July 2019. The top 5-10 cm of lake sediment was collected from ~30 cm water depth and stored in Whirlpack bags. The samples were kept at -20 °C at camp and then shipped to the University of Toronto, Mississauga. BrGDGTs were ultimately obtained from 6 grams of sediment following successive purification via column chromatography. The purified samples were analyzed for brGDGT abundance via ultra-high-performance liquid chromatography - mass spectrometry using an Agilent Technologies 1290 Series II UHPLC coupled to an AB Sciex 4500Q triple quadrupole mass spectrometer at the University of Toronto, Mississauga. The resultant brGDGT distributions are presented as relative abundances, which were then used to calculate a variety of common indices (MBT’5me, CBT’, and IR6me). To assess climate sensitivity, monthly ... : The purpose of this work is to investigate distributions of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in lakes of Alaska, Yukon, and Northwest Territories and to quantify regional relationships between modern brGDGT assemblages and climate parameters. BrGDGTs are a popular indicator of past climate conditions and are well-studied on a global scale. However, the degree to which brGDGTs vary with climate parameters, such as temperature, varies with the environment in which the brGDGTs are produced and may further vary regionally. As such, maximizing the precision of reconstructed climate conditions from the brGDGT climate proxy requires the development, and subsequent employment, of environmentally appropriate calibrations. Until now, brGDGT distributions have remained uncharacterized in Alaska and NW Canada, where the number of available climate proxies is limited. This work will therefore provide new opportunities to better understand past climate and how climate varies through time in this ...