The study looked at sediment samples from the intertidal zone on the west coast of the Bohai Bay. They found that sediments became finer and better sorted from north to south. Surface sediments were fine sands in the north and silty clay in the south. Sediment cores showed a layer of uniform fine sand below the surface, with more clay below that. Changes in water and sand flow into the sea have led to coarser sediments in the area.