Hydroxylated isoprenoidal GDGTs in the Nordic Seas

The emergence of modern sea ice cover in the Arctic Ocean

“…The occurrence of the phytoplanktic sterol brassicasterol (a proxy indicator of openwater conditions 18 ) ( Fig. 3 and Supplementary Table 3) and elevated SST estimates based on distributions of GDGTs and hydroxyl GDGTs 32,33 (Fig. 3 and Supplementary Table 4) also suggests an absence of perennial sea ice during the studied interval.…”

“…The recently discovered hydroxyl GDGTs 68 have been shown to infer SSTs on a global scale 33 and to indicate the presence of polar waters in the Arctic Ocean 32 . Fietz et al 32 proposed a so-called OH-GDGT% index and a promising SST calibration (slightly modified from Huguet et al 33 ) based on the hydroxyl and isoprenoid GDGTs:…”

“…Fietz et al 32 proposed a so-called OH-GDGT% index and a promising SST calibration (slightly modified from Huguet et al 33 ) based on the hydroxyl and isoprenoid GDGTs:…”

Lake Water Depth Controlling Archaeal Tetraether Distributions in Midlatitude Asia: Implications for Paleo Lake‐Level Reconstruction

“…Recently, %OH‐GDGTs has been proposed as a paleothermometer in view of the significantly negative correlation between %OH‐GDGTs and temperature mainly in marine environments (Fietz et al, ; Huguet et al, ; Lü et al, ). The applicability of this novel proxy is supported by a molecular dynamics simulation study showing that the additional OH group can help to maintain trans‐membrane transport in cold environments (Huguet et al, ).…”

“…Another group of archaeal tetraethers, OH‐GDGTs with 1–2 hydroxyl groups in the biphytanyl moieties of isoGDGTs (Figure S1), could be synthesized by both Euryarchaeota and Thaumarchaeota (Liu et al, ). In the marine environment, the relative abundance of OH‐GDGTs (%OH‐GDGTs) is negatively correlated with sea surface temperatures (Fietz et al, ; Huguet et al, ; Lü et al, ). In lacustrine settings, however, a recent study in Lake Qinghai shows that variations of %OH‐GDGTs in down‐core sediments track past changes in lake water depth rather than temperature over the past 8 kyr, suggesting the potential of %OH‐GDGTs as a lake‐level proxy (Wang, Liu, et al, ).…”