No abstract

No abstract

We investigated the spatial distribution of glycerol dialkyl glycerol tetraethers (GDGTs), alkenones, and polyunsaturated fatty acids in particulate organic matter collected at four sites along a depth transect from the continental shelf to the Okinawa Trough in the East China GDGTs by an eastward current. At the slope and Okinawa Trough sites, TEX 86 -based temperatures were nearly constant in the water column deeper than 300 m and corresponded to temperatures at the surface and near-surface waters rather than in situ temperatures. This observation is consistent with a hypothesis that Thaumarchaeota cells produced in surface waters are delivered to deeper water and also indicates that the residence time of suspended GDGTs in the deep water column is large enough to mix the GDGTs produced in different seasons.

The East China Sea (ECS) responds to changes in the strength of the Kuroshio and East Asian monsoon activity. Multidecadal resolution records of the palaeotemperature indices ${\rm TEX}_{{\rm 86}}^{{\rm H}} $ and $U_{37}^{K'} $ from core KY07‐04 PC‐1 show that the hydrology of the ECS responded to variability in the East Asian winter monsoon. Unlike Mg/Ca‐derived sea surface temperatures, which show neither warming nor cooling trends during the Holocene, the ${\rm TEX}_{{\rm 86}}^{{\rm H}} $ record showed a general warming trend at a rate of 0.2°C ka−1. This warming was attributable to shrinkage of the Yellow Sea Central Cold Water and/or weaker winter cooling of the surface water. The ${\rm TEX}_{{\rm 86}}^{{\rm H}} $ record indicated a centennial‐scale variability with an ∼1°C amplitude superimposed on the warming trend that reflected changes in the East Asian winter monsoon and/or the Kuroshio. Temperature minima appeared at ca. 3.0, 4.7, 6.2, 7.9 and 9.0 ka, and spectral analysis of the last 7 ka revealed significant peaks with periodicities of approximately 210, 250, and 440 years that were close to those observed in solar radiation. The reconstructed winter monsoon variability is consistent with Chinese documentary records for the last two millennia. Copyright © 2012 John Wiley & Sons, Ltd.