Utility of brGDGTs as temperature and precipitation proxies in subtropical China

Abstract

Bacterial branched glycerol dialkyl glycerol tetraethers (brGDGTs) have been successfully used as quantitative climate proxies for reconstructing annual mean air temperature (MAT) and soil pH from sediments. However, reconstructions derived from brGDGTs in regions with diverse hydrological and atmospheric conditions require further refinement. In this study, we investigated the suitability of brGDGTs as temperature and precipitation proxies from surface soils on opposite slopes of Mount Fanjing in subtropical China. The results show a clear altitudinal lapse rate of MBT′5ME-derived MAT and between-slope differences in MAT at given altitude. Moreover, the MBT′5ME-derived MAT values are more strongly related to the MAT from March to November than that of the whole year. A turning point is also observed from the measured pH and CBT′-derived pH gradients at altitude of 1400 m~1500 m, in accordance with the fog horizon, where precipitation reaches the maximum value. The findings prove that brGDGTs from soil transects can be used as indicators for reconstructions of climate parameters from subtropical regions of China.

Predominance of hexamethylated 6-methyl branched glycerol dialkyl glycerol tetraethers in the Mariana Trench: source and environmental implication

“…The sample information was listed in the Supplement. The soil samples are from globally distributed soils (De Jonge et al, 2014a;Ding et al, 2015;Xiao et al, 2015;Yang et al, 2015;Lei et al, 2016;Wang et al, 2016Wang et al, , 2018Wang et al, , 2019Li et al, 2018;. The peat samples are from 96 different peatlands around the world (Naafs et al, 2017).…”

Evidence for seasonality in early Eocene high latitude sea-surface temperatures

“…5). It is known that brGDGT production is seasonally influenced and a warm-season bias is present in some modern soils (Wang et al, 2018), although it appears that the brGDGT distribution in peat is dominated by production below the water table where the seasonal temperature cycle is muted (Naafs et al, 2017). However, there are uncertainties in the interpretation of brGDGT temperature estimates as information on the ecology of the bacterial producers of brGDGTs is scarce with most producers of these lipids unidentified (Naafs et al, 2017).…”

Holocene mean annual air temperature (MAAT) reconstruction based on branched glycerol dialkyl glycerol tetraethers from Lake Ximenglongtan, southwestern China

“…Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are ubiquitous in terrestrial environments including soils, peats and lacustrine sediments, have demonstrated a strong potential for paleotemperature reconstruction (e.g., Weijers et al, 2007;Schouten et al, 2013;Wang et al, 2018). The degrees of cyclization and methylation of branched tetraethers (CBT and MBT or MBT´, respectively), are correlated with environmental pH and temperature (Weijers et al, 2007;Peterse et al, 2012).…”