Tetraether lipids from the southern Yellow Sea of China: Implications for the variability of East Asia Winter Monsoon in the Holocene

Abstract

To better understand the origin and distribution of organic matter (OM) in the Yellow Sea (YS) and to delineate potential interactions between the atmosphere and the marine system during the Holocene, we reconstructed terrestrial input and temperature variation for the last 8.8ka BP, using glycerol dialkyl glycerol tetraethers (GDGTs) obtained from a 4.4m sediment core (YSC-1) from the southern YS. The archaea-derived isoprenoid GDGTs (iGDGTs) were dominated by GDGT-0 and crenarchaeol. The iGDGTs and bacteria-derived branched GDGTs (bGDGTs) correlated well and varied in opposition to the BIT (branched vs. isoprenoid tetraether) index. This may be due to varying river runoff and influence of the YS Coastal Current (YSCC) and YS Warm Current (YSWC), related to the East Asia Winter Monsoon (EAWM), which made the BIT proxy less suitable for tracing soil OM input to the YS. TEX86 (tetraether index of tetraethers consisting of 86 carbons)-derived sea surface temperature values (SST) varied from 9 to 16°C, close to the SST in the YS cold season. The MBT/CBT (methylation of branched tetraethers and cyclization of branched tetraethers)-derived continental temperature ranged from 10 to 19°C, indicating an annual mean air temperature for the middle and low drainage basin of the YS. These two temperature records were decoupled but both correlated with the variation in the EAWM, suggesting an intimate link between EAWM and temperature variation in East Asia.