Determination of geochronology and sedimentation rates of shallow lakes in the middle Yangtze reaches using 210 Pb, 137 Cs and spheroidal carbonaceous particles

Chen, Xu; Qiao, Qianglong; Mcgowan, Suzanne; Zeng, Linghan; Stevenson, Mark A; Xu, Lei; Huang, Chunling; Liang, Jia; Cao, Yanmin

Abstract

Accurate chronologies for recent sediments of shallow lakes in the Yangtze floodplain are critical to calibrate proxy records for reconstructing environmental changes during the past century. This study presents the results of detailed 210Pb analysis from eight lake sediment cores collected from the middle Yangtze reaches, southeast China. Unsupported 210Pb activities generally declined exponentially with mass depth in the eight cores. The chronologies and sedimentation rates for the sediment cores were calculated using different 210Pb-based mathematical models. The 137Cs chronomarker (i.e. the 1963 fallout peak) and the spheroidal carbonaceous particle (SCP) chronomarker (i.e. the start of the rapid increase in 1970 AD) were selected to validate the 210Pb dating. Sedimentation rates derived from different models were validated using historical data including lake area, arable land area, sediment discharge and reservoir volume in the Yangtze basin. The SCP-corrected CRS (constant rate of supply) model performs better than other models, based on validation using historical documents in the Yangtze basin. The 137Cs chronomarker might be erroneous due to catchment-driven 137Cs inputs from soil erosion and post-depositional diffusion. Both SCPs and 137Cs are susceptible to inputs from catchment soil erosion, but SCPs show no apparent degradation and post-depositional changes in lake sediments. The SCP profile provides a relatively reliable chronomarker, which can be used for validating 210Pb chronologies in these floodplain lakes. Generally, sedimentation rates in the eight lakes were less than 0.2 g cm-2 yr-1 before the 1930s, and then increased to a peak in the 1960s. Afterwards, sedimentation rates decreased and remained low after the 1980s.

Citation

Chen, X., Qiao, Q., Mcgowan, S., Zeng, L., Stevenson, M. A., Xu, L., …Cao, Y. (2019). Determination of geochronology and sedimentation rates of shallow lakes in the middle Yangtze reaches using 210 Pb, 137 Cs and spheroidal carbonaceous particles. CATENA, 174, 546-556. https://doi.org/10.1016/j.catena.2018.11.041

• Journal Article Type: Article
• Acceptance Date: Nov 30, 2018
• Online Publication Date: Dec 11, 2018
• Publication Date: Mar 1, 2019
• Deposit Date: Dec 3, 2018
• Publicly Available Date: Dec 12, 2019
• Journal: CATENA
• Print ISSN: 0341-8162
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 174
• Pages: 546-556
• DOI: https://doi.org/10.1016/j.catena.2018.11.041
• Public URL: https://nottingham-repository.worktribe.com/output/1357556
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0341816218305368
• Additional Information: This article is maintained by: Elsevier; Article Title: Determination of geochronology and sedimentation rates of shallow lakes in the middle Yangtze reaches using 210Pb, 137Cs and spheroidal carbonaceous particles; Journal Title: CATENA; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.catena.2018.11.041; Content Type: article; Copyright: © 2018 Elsevier B.V. All rights reserved.