Wang, F.; Zong, Y.Q.; Li, J.F.; Tian, L.Z.; Shang, Z.W.; Chen, Y.S.; Jiang, X.Y.; Yang, J.L.; Yang, B., and Wang, H., 2016. Recent sedimentation dynamics indicated by 210Pbexc and 137Cs records from the subtidal area of Bohai Bay, China.
To determine sedimentation rate changes across an open marine area along the west coast of Bohai Bay, more than 50 short sediment cores were collected and analyzed with their sedimentation rates estimated by excess 210Pb (210Pbexc) and 137Cs in the sediment. The surveys enabled us to explore the relationship between sediment supply changes from the rivers and the spatial/temporal deposition patterns in the shallow marine areas. Several core records show that sedimentation rates can be overestimated by the conventional constant initial concentration model based on the 210Pbexc curves alone. The overestimation was caused by a change of 210Pbexc in the top layers of these cores and this is confirmed by comparing 210Pbexc curves with the respective 137Cs curves. This phenomenon is likely caused by sediment erosion or redeposition of the surface sediment at the seabed, implying present-day active sedimentary processes as a result of the drastic decrease in sediment supply from the rivers during the last 50 years. The sedimentary boundary where sedimentation rate changed is largely comparable with the timing of sediment supply change according to the river discharge data, which can be used as a local time marker for sedimentation rate comparison.
