Modern calibration of biomarkers in the marine channels of the Canadian Arctic Archipelago using the PIP25 approach
Two lipid biomarkers, IP25 (a highly branched isoprenoid hydrocarbon; an ice proxy containing 25 carbon atom skeleton) and brassicasterol (phytoplankton derived biomarker), accumulate and become preserved in the marine sediments on the seafloor. IP25 is produced by sea ice algae (marine diatoms) while brassicasterol is produced by a suite of open-water algae (dinoflagellates, diatoms), allowing for determination of sea surface conditions in relation to sea ice conditions during accumulation. Absence of IP25 in marine sediments can indicate permanent sea ice coverage or absence of sea ice completely. High IP25 concentrations reveal sea ice conditions by which sea ice algae can thrive. High brassicasterol concentrations are an indicator of ice free surface conditions, whereas, an absence of brassicasterol would suggest sea ice coverage. Following extraction and quantification via Gas Chromatography Mass Spectroscopy, their respective concentrations can be related to each other in a ratio known as PIP25 (Phytoplankton-IP25 index) to reconstruct specific sea ice conditions (marginal ice zone, perennial ice cover, ice free, etc.). The PIP25 approach allows for currently accumulating IP25 and brassicasterol to be related to observed modern sea ice conditions, therefore providing a regionally appropriate calibration for the study of past conditions in the geological record. This study focuses on the modern calibration of these biomarkers in the marine channels of the Canadian Arctic Archipelago.
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