Historical change of carbon burial in Late Quaternary sediments of the ancient Yellow River delta on the west coast of Bohai Bay, China

Authors

Guangming Zhao, China Geologic Survey
Siyuan Ye, China Geologic Survey
Lei He, China Geologic Survey
Hongming Yuan, China Geologic Survey
Xigui Ding, China Geologic Survey
Jin Wang, China Geologic Survey
Edward Allen Laws, Louisiana State University

Document Type

Article

Publication Date

10-1-2020

Abstract

The ancient Yellow River Delta (YRD) on the west coast of the Bohai Bay is possibly a huge carbon sink due to the high runoff and sediment load of the Yellow River, which transfers huge amounts of particulate carbon from terrestrial sources to the Bohai Sea. In this study, a 30.76 m long core (BXZK11), drilled in 2016, has been analyzed for AMS ¹⁴C dating, grain size, foraminifera, organic carbon (OC), total nitrogen (TN), and stable carbon isotope ratios (δ¹³C) to provide insights into the historical changes of carbon burial in Late Quaternary sediments of the ancient YRD. The results show that the sedimentary environments are divided into six depositional units in core BXZK11. The biggest contributor to organic carbon apparent mass accumulation rate (OCAMAR) is the negative covariance between apparent sedimentation rate (ASR) and OC. The average of OCAMAR is 20.76 g/(m² yr) during the Holocene. The rates are highest in delta front deposits and lowest in shallow sea environments. Compared with the modern YRD, BXZK11 exhibits rather low ASR and OCAMAR, indicative of the enormous variations of Yellow River sediment load into the sea and the significant difference of carbon sequestration capacity of YRD at different periods. C3 plants of the delta wetland gradually develop without C4 plant input as the delta transgresses after sea level stabilization. The sediments have been characterized by decreasing terrestrial organic matter (TOM) since 6500 cal. a BP, reflecting the decline of Yellow River freshwater discharge. Both the 8.2 ka event and the weak Asian monsoon summer event at 6265 cal. a BP correspond well with the low TOM in BXZK11. The implication is that climate may affect the dynamics of carbon burial by regulating terrestrial inputs.

Publication Source (Journal or Book title)

Catena

Recommended Citation

Zhao, G., Ye, S., He, L., Yuan, H., Ding, X., Wang, J., & Laws, E. (2020). Historical change of carbon burial in Late Quaternary sediments of the ancient Yellow River delta on the west coast of Bohai Bay, China. Catena, 193 https://doi.org/10.1016/j.catena.2020.104619