Influences of the 1855 AD Huanghe (Yellow River) Relocation on Sedimentary Organic Carbon Burial in the Southern Yellow Sea

Jianying Liu,Da-Wei Li,Meixun Zhao,Chih-An Huh,Yang Ding,Weifang Chen,Tiantian Ge

doi:10.3389/fmars.2022.824617

Abstract

The Huanghe (Yellow River) supplies large amount of sediments and terrestrial organic carbon (OC) to the eastern Chinese marginal seas. A relocation of the Huanghe outlet from the southern Yellow Sea (YS) to the Bohai Sea occurred in 1855 AD, however, detailed knowledge about the impact of this relocation on sedimentary source and OC burial in Chinese marginal seas is still critically lacking. In this study, we present total OC content and its isotope (δ13C), along with bulk total organic carbon (TOC)/total nitrogen (TN) molar ratio and lipid biomarker contents, in a sediment core HH12 from the southern YS with sediment age spanning the last 300 years. We find that TOC and terrestrial lipid biomarker mass accumulation rates were lower between 1855 AD and 1950 AD than that prior to 1855 AD in core HH12; and in accordance, both TOC/TN ratio and δ13C records indicate a gradual decrease of terrigenous source contributions to sedimentary OC. This suggests that the relocation of the Huanghe outlet reduced the transport of terrestrial OC to the southern YS. However, the δ13C record also indicates a relative increase of terrestrial OC contribution to sedimentary OC after 1950 AD, and the most likely explanation is increased contributions from the old Huanghe delta erosion and Korean rivers. Future studies should focus on better constraining the variations of terrestrial and marine endmembers with δ13C and Δ14C analyses of specific biomarkers to examine these linkages.

Highlights

Accounting for more than 80% of annual global marine sediment organic carbon (OC) burial (Burdige, 2005), marginal seas play an important role in removing carbon from the active biosphere to the inactive geosphere
The average sedimentation rate of core HH12 was calculated as 0.16 cm yr−1, which is similar to 0.15 cm yr−1 in core 35009 collected in the same site (35.00◦N, 123.50◦E, water depth 75.8 m; Zhou X. et al, 2014) as us basing on high resolution 210Pbex and137Cs profiles, and is consistent with sedimentation rate of 0.1-0.2 cm yr−1 in the CSYSM (Qiao et al, 2017)
We proposed that higher average chain length (ACL) values of core HH12 before 1855 AD was the result of higher terrestrial OC contribution from the Huanghe source, and lower values during 1855-1950 AD was the result of reduced terrestrial OC contribution from the Huanghe river due to the extended transport distance

Summary

Introduction

Accounting for more than 80% of annual global marine sediment organic carbon (OC) burial (Burdige, 2005), marginal seas play an important role in removing carbon from the active biosphere to the inactive geosphere. Since 1578 AD, dikes were built to cut off the northeast flow in Shandong province and the Huanghe was fixed to capture the Huai River course draining into the southern YS, which ensured continuous input of the Huanghe sediment into the southern YS from 1578 AD to 1855 AD. During this period, the sediment discharge of the Huanghe increased to ∼1560 Mt yr−1 (Wu et al, 2020). Since the late 1950s, the sediment yield from the Huanghe has experienced a dramatic decline to 150 Mt yr−1 in 2000s (Wang et al, 2011)

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Discussion

Conclusion