Anthropogenic activities have decreased the sediment transport from catchment to the river-dominated continental margin mainly through river damming that controlled the estuarine and associated shelf modern sedimentation. In this study, radioisotopes ²¹⁰Pb (²¹⁰Pb_ex and ²²⁶Ra) and ¹³⁷Cs, grain size, and X-radiograph were combined to evaluate the modern sedimentary processes in the Yangtze River Estuary (YRE). We found that seabed cores collected on the estuary and associated shelf show a direct temporal correlation between decreases in initial activity and burial flux of ²¹⁰Pb_ex and suspended sediment load in relation to river damming and soil conservation from 1950 to 2016. Most of sediment cores are characterized by low, uniform and reverse ²¹⁰Pb patterns at surface and negligible sediment accumulation rates (SARs), indicating that due to the limited sediment supply following the construction of the Three Gorges Dam in 2003, erosion and remobilization of fine-grained sediments by energetic tidal currents and biological mixing tends to have become determinant forces in controlling the fate of modern sediment burial in the YRE. Moreover, these results indicated that decline in sediment load and additional input of eroded materials will largely violate the basic assumption of constant ²¹⁰Pb flux, raising a substantial challenge for ²¹⁰Pb chronology in the river-dominated continental margins. However, we suggest that radiotracer ²¹⁰Pb could provide critical information for understanding the complex the sedimentary processes (e.g., terrestrial sediment supply and redistribution by tidal currents) and assessing past environmental status on the river- and/or tidal-dominated estuaries subject to human modification.

人为活动减少了沉积物从集水区到以河流为主的大陆边缘的运输，主要是通过控制河口和相关架子现代沉积的河坝。在这项研究中，结合了放射性同位素²¹⁰ Pb（_ex的²¹⁰ Pb和²²⁶ Ra）和¹³⁷ Cs，粒度和X射线照相技术，评估了长江口（YRE）的现代沉积过程。我们发现，在河口和相关架子上收集的海底岩心显示出初始活动的减少与²¹⁰ Pb _ex的埋藏通量之间存在直接的时间相关性。1950年至2016年间与河流拦坝和水土保持有关的悬浮泥沙和悬浮泥沙负荷。大多数泥沙岩心的特征是地表低，均匀和反向²¹⁰ Pb模式，而沉积物积聚率（SARs）可忽略不计，这表明由于沉积物有限随着2003年三峡大坝的修建，高能潮流对细粒沉积物的侵蚀和迁移以及生物混合作用已成为控制YRE现代沉积物命运的决定性力量。此外，这些结果表明，沉积物负荷的减少和侵蚀材料的额外输入将大大违反恒定的²¹⁰ Pb通量的基本假设，从而对²¹⁰河流占主导的大陆边缘的铅年代学。但是，我们建议放射性示踪剂²¹⁰ Pb可以为了解复杂的沉积过程（例如，陆地沉积物的供应和潮汐流的再分配）以及评估受人类支配的河流和/或潮汐河口过去的环境状况提供关键信息。修改。