Sedimentary Records of the Dramatic Environmental Changes in the Lingdingyang Bay of the Pearl River Estuary in Southern China

To understand the spatial distribution and vertical evolution of sediments in the Pearl River Estuary in recent decades, two sediment cores (80 cm long) from the western and eastern areas of the outer Lingdingyang Bay (LDB) were analyzed in terms of grain size (GZs) and organic matter content. The results showed that the sediment profiles of the two cores could be divided into two time sections with clear changes in grain size. The core in the western region showed a coarse-to-fine trend from the lower to the upper section, whereas that in the eastern region showed a fine-to-coarse trend. Parametric correlations of the cores suggest that different sediment sources and hydrodynamic environments resulted in opposite sediment trends in the two cores. Based on some reported sedimentation rates, the GZs of the western and eastern cores responded well to changes in the average annual fluvial sediment load and tidal range in the western and eastern areas of the LDB, respectively. The increase in grain size and decrease in sorting value in the upper section of the two cores can provide evidence of a strengthened tidal current in recent years. Our results can provide a baseline for future studies on the responses of marine environment to anthropogenic activities in the Guangdong-Hong Kong-Macao Greater Bay Area.