Biogenic and abiogenic sedimentation in the northern East China Sea in response to sea-level change during the Late Pleistocene

In order to understand fluctuations in terrestrial and marine environments in response to sea-level change during the last 42 ky, we investigated sedimentation of biogenic and abiogenic components in core MD982195, collected from the northern East China Sea (ECS), one of the largest marginal seas in the world. Amino acids (AAs), major nitrogen compounds in marine organic matter (OM), can be protected inside biogenic material and survive the decomposition process. The total AAs were highly correlated with organic carbon (OC) (r = 0.91; p < 0.05) but less with total nitrogen (TN) (r = 0.76; p < 0.05). Therefore, total AAs and OC contents should reflect primary production (PP) more than TN in core MD982195. PP was approximately constant during 42–15 ka, increased in 15–14 ka was kept constant until 7 ka. Then PP increased from 5 ka to the present. IMAGES program is generally interested in high-resolutional reconstruction of paleo-environments in the area with high sedimentation rate, which is mainly due to abundant supply of lithogenic matter. The positive correlation of lithogenic matter with nonarboreal pollens (NAP) abundance suggests that lithogenic matter and NAP were mainly transported from the coastal lowlands created by the large drop in sea level during the glacial period. Large, millennial-scale fluctuations in sea-surface temperature and salinity did not always correspond to sedimentation pulses of OC and lithogenic matter. Sedimentation of biogenic and abiogenic components was more affected by sea-level change, which controls the positions of the coastline and river mouths and the presence of terrestrial environments on the exposed continental shelf. The Japan Sea is also sensitive to sea-level change because of the shallow sills connecting it to other ocean basins.