High-Frequency Variation of Suspended Particle Matter in Sea Area Adjacent to Yangtze Estuary Based on Underway Observation

Based on a comprehensive marine scientific survey conducted in the sea area adjacent to the Yangtze Estuary from May 27 to May 31, 2018, a fixed point and continuous spectrum observation with the ship-based underway apparent spectrum observation system is carried out. Simultaneous observation results of a rapid multi parameter water quality meter and an acoustic Doppler current profiler are also incorporated to study the high-frequency variation of the suspended particulate matter (SPM) and its influencing factors. The results show that the SPM concentration in the sea area adjacent to the Yangtze Estuary demonstrates high-frequency variations and significant influence by the tide. During the ebb period, the SPM concentration at the fixed station distinctly increases first and then decreases, with high value corresponding to the high current velocity. Underway transect observation results exhibit obvious regional differences in the variation characteristics of the SPM in a short time. In a shallower area, the local resuspension process plays a dominant role, with a close relationship between SPM concentration and the current velocity. In contrast, the concentration variation of the SPM in farther offshore areas with deeper depth may be related to the Yangtze River diluted water process.