Grain-size characteristics of surface sediment and sedimentary environment in Zhanjiang Bay

Based on the results of particle size analysis of 61 surface sediment samples collected in October, 2020 in Zhanjiang Bay, Guangdong, China, the particle size parameters of sediments were summarized, and the sediment types were classified. The Pejrup triangle diagram was used to divide the sedimentary dynamic environment of Zhanjiang Bay. The Gao-Collins particle size trend analysis model was used to explore the sediment migration trend. Results show that there are five types of surface sediments in Zhanjiang Bay, among which sand, silty sand, and sandy silt are the most widely distributed. The particle size composition is mainly fine sand, and the average particle size is 3.93Φ. The sorting is poor. The particle size distribution curve is mainly positive and normal distribution. The discriminant diagram of sedimentary dynamics reveals that the sedimentary hydrodynamic force in Zhanjiang Bay is strong; and it is generally weaker inside the bay than outside the bay and gradually weakens oceanward. The particle size trend analysis shows that the whole water in Zhanjiang Bay moves to the tidal deep trough in the south, while water of outer bay flows counterclockwise around the sedimentary center. The movement and distribution of surface sediments in the bay are mainly affected by sediment sources and sedimentary dynamic environments such as tides, waves, and coastal current. In recent years, the influence of human activities has become more obvious.