How did the climate and human activities modulate the sedimentary evolution of the central Yellow Sea Mud, China

The Central Yellow Sea Mud (CYSM) archived important signals of regional environment and climate changes during the Holocene. We performed high-resolution analysis of two sediment cores taken from the CYSM, including measurements of radiocarbon chronology and grain size, as well as the mineralogical and geochemical measurements on the sediment samples. The results indicate that the Yellow River were likely a dominant source of the CYSM before 6.8 ka BP, with minimal contributions from the local small rivers in the Shandong Peninsula and Korean Peninsula, as confirmed by the mineralogical and geochemical evidences. After 6.8 ka BP, the fine-grained sediments accumulated in the CYSM presented a mixture of those from both the Yangtze and Yellow River with an individual contribution of 55 +/- 8% and 45 +/- 6%, respectively, as the sea level reached its highstand and initiated the establishment of modern shelf circulation. The drastic environmental changes in the Yellow River basin after 4.0 ka BP driven by the weakened East Asian Summer Monsoon and enhanced human activities that significantly increased the sediment yield from the Chinese Loess Plateau should be responsible for the abrupt increase in the fine-grained sediment (< 2 mu m) accumulation in the CYSM. After 1.4 ka BP the decrease in precipitation in the Yellow River basin resulted in the imbalance between sediment yield and river runoff, which perhaps induced lower channel aggradation and frequent avulsions, and consequently decreased the accumulation rate of the Yellow River-derived sediment in the CYSM. During the Holocene, the rising sea level played a primary role in shaping the sedimentation of the CYSM including the retreated coastline and estab-lishment of shelf circulation system, whereas the monsoonal climate and human activities dominated the terrestrial sediment supply and accumulation in the CYSM after 4.0 ka BP.

Automated summary

This study provides insights into the environmental and climate changes in the Central Yellow Sea Mud (CYSM) during the Holocene. The contributions of the Yellow River and Yangtze River to the CYSM sedimentation varied over time, with sea level rise, weakened East Asian Summer Monsoon, and human activities playing key roles in sediment transport and accumulation.