TY - JOUR
T1 - Determination of geochronology and sedimentation rates of shallow lakes in the middle Yangtze reaches using 210Pb, 137Cs and spheroidal carbonaceous particles
AU - Chen, X.
AU - Qiao, Q.
AU - McGowan, S.
AU - Zeng, L.
AU - Stevenson, M.A.
AU - Xu, L.
AU - Huang, C.
AU - Liang, J.
AU - Cao, Y.
N1 - CODEN: CIJPD
Funding details: National Natural Science Foundation of China, NSFC, 41202248, 41530753, 41572343
Funding details: China University of Geosciences, Wuhan, CUG, G1323511656
Funding text 1: We acknowledge Yang Xiangdong, Zhang Enlou, Dong Xuhui, Mao Xin, Du Chenchang, Xia Weilan, Tao Jingkui and Yao Shuchun for field and laboratory assistance. This study was supported by the National Natural Science Foundation of China ( 41572343 , 41530753 and 41202248 ) and the Fundamental Research Fund for National University, China University of Geosciences, Wuhan ( G1323511656 ).
PY - 2019
Y1 - 2019
N2 - 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 CE) 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 The SCP-corrected CRS (constant rate of supply) model performs better than other models, based on validation using historical documents in the Yangtze basin.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 <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.
AB - 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 CE) 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 <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.
KW - 210Pb radiometric dating
KW - Lacustrine sediment
KW - Multiple dating models
KW - Spheroidal carbonaceous particles
KW - The Yangtze floodplain
U2 - 10.1016/j.catena.2018.11.041
DO - 10.1016/j.catena.2018.11.041
M3 - Article
SN - 0341-8162
VL - 174
SP - 546
EP - 556
JO - Catena
JF - Catena
ER -