Environmental change in Yellow Sea during the last deglaciation to the early Holocene (15,000-8,000 BP)

Abstract

This study is the first reconstruction of the paleoenvironment and paleovegetation during the Holocene (interglacial) and last deglaciation periods of the Yellow Sea. Carbon isotope and biomarker (n-alkane and alkenone) compositions of organic carbon matter (OM) from core 11 YS PCL14 collected from the central Yellow Sea recorded past changes in East Asian Monsoon (EAM) climates. The result shows the variability of the EAM affected the sedimentary profile of total organic carbon (TOC), the stable isotopes of bulk organic carbon (delta C-13(org)), the atomic ratio of carbon and nitrogen (C/N ratio), and biomarker content. The oscillations of TOC along the sediment core might be associated with the paleoceanographic conditions (changes in the sea level) related to the contribution of the autochthonous and allochthonous OM input. Two climatic conditions were distinguished (warm/humid and cold/dry) based on the n-alkane proxy, and the observed changes in delta C-13 of individual n-alkane (delta C-13(ALK)) between the Holocene and last deglaciation were attributed to changes in plant distribution/type. A shift in vegetation type between climatic periods occurred as a result of different photosynthetic response to CO2 and temperature among C-3 and C-4 plants. The most interesting new finding of this work is the fact that alkenone derived temperature changed independently with global climate change, which might be related to the influence of the Kuroshio current in the Yellow Sea. The variations in the intensity of the EAM could be the main mechanism accounting for the paleoenvironmental and paleoceanographic variation observed in the central Yellow Sea. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.