부산대학교 도서관

The TEX 86 paleothermometer was applied for reconstructing sea surface temperature (SST) from glycerol dialkyl glycerol tetraethers (GDGTs) in marine sediments. It has become clear that GDGT-producing archaea live throughout the water column, with maximum concentration usually well below the surface mixed layer of the ocean. Why the TEX 86 parameter correlates well with SST remains poorly understood. Here we evaluate the fidelity of the TEX 86 thermometer using surface sediments and suspended particles from the Yellow Sea (YS), a shallow marginal sea between China and the Korean peninsula. The highest concentration of GDGTs in the water column at a site (A02) from the middle of the YS occurred in the bottom layer, at 70 m. This contrasts with phytoplankton lipids, which were most abundant near the surface. Consistent with the maximum abundance of GDGTs in bottom water, TEX 86 values in surface sediments correlated better with mean annual bottom water temperature (BWT, R 2 0.81) than with mean annual SST ( R 2 0.74). Moreover, TEX H 86 temperature derived from a global core top calibration gave values 0.1–9.4 °C colder than mean annual SST but much closer to mean annual BWT (2.7–4 °C). Lastly, TEX 86 and U 37 K ′ paleotemperature values displayed distinctly different trends over the last 12 kyr for sediments from the shelf between the YS and the East China Sea (ECS), consistent with the notion that TEX 86 and U 37 K ′ reflect different temperature signals. This preponderance of evidence supports the use of TEX 86 as a proxy for BWT in the YS. Therefore, we propose a local calibration of TEX L 86 for reconstructing mean annual BWT (TEX L 86 = 0.03 BWT-0.94; R 2 0.86, n = 22, P < 0.0001). The combination of alkenone ( U 37 K ′ ) derived SST with TEX L 86 BWT yielded a quantitative reconstruction of the vertical thermal gradient in the YS, and an insight into understanding the impact of the Kuroshio Current and East Asian monsoon on the YS. [ABSTRACT FROM AUTHOR]