Vertical distribution characteristics of suspended particulate matter and their influential factors in the central Yellow Sea during spring and summer

This study revealed the vertical distribution characteristics of suspended particulate matter (SPM) and explored the influences of plankton distribution and hydrodynamic conditions on variations in SPM, based on observational data collected using LISST-100 and RBR620 CTD instruments in the central Yellow Sea during spring and summer. In spring, the water column below 10 m was vertically well-mixed, and a phytoplankton bloom observed in the subsurface layer that spread across depths of 10-25 m for approximately 4 days. In summer, the water column exhibited a distinct three-layer structure with strong stratification at depths of 15-20 m and 25-35 m. The high concentration of SPM observed in the subsurface layer during spring was attributed to a bloom of microphytoplankton with particle sizes of 10-20 μm. In stratified waters during summer, the presence of mesozooplankton with particles >250 μm near the double stratification contributed to high SPM concentrations. In both spring and summer, particles sized 26-38 μm predominated near the bottom layer. Local resuspension of sediments contributed to the high SPM concentrations observed near the bottom layer in summer, while the variations in high concentrations near the bottom layer in spring were primarily influenced by horizontal convection processes of SPM.