TYPES AND SIZE OF SUSPENDED PARTICLES IN A TYPICAL CROSS SECTION AT THE CHANGJIANG ESTUARY AND INFLUENCE FACTORS

During the NSFC cruise in October 2010, several water samples were recovered along a typical section at the Changjiang Estuary and its adjacent area for study of suspended matters. After filtration, the materials remained were examined under Electronic Microscope and by Energy Spectrometer. Grain size analysis was carried out for the samples. In this typical section, there are four types of particles, mineral debris, bioclasts, organic particles and floc-particles. The contents of mineral debris and organic particles are higher inshore and lower offshore, whereas the bio-particles are distributed in an opposite pattern. However, floc-particles have no obvious change from DH1 to DH6. There is a good linear relationship between floc-particles and organic particles, but a negative relationship between mineral debris and bioclasts. In the suspended matters, the particles smaller than 10 microns in size account for 70%, and those smaller than 20 microns account for 90%, while the average particle size is decreasing offshore. It is believed that the types of particles are mainly controlled by the factors of continental input, biological process, flocculation and resuspension, depending upon the movement of water masses.