关键词: 谱分析, 粒径, 絮凝体, LISST, 长江口, 徐六泾

Abstract: The temporal change in flocs size of fine suspended sediments was measured in Xuliujin of the Changjiang Estuary in June of 2003, by using an in situ laser diffraction particle sizer, the laser in situ scattering and transmissomerty100(LISST100). The spectrum analysis was applied to analyze the fluctuation of flocs diameter during the spring tide and the neap tide. The results showed that the quasiperiod of flocs diameter in the surface water during the spring tide included 7.86 h, 3.93 h and 2.95 h; those in the same water during the neap tide included 8.38 h and 3.14 h; those in the bottom water during the spring tide included 3.33 h and 1.19 h. The analysis of the quasiperiods of flocs diameter showed that flocs diameter was responded to the period of the current velocity, which was fluctuating through the tidal periods. The periodical varying current velocity resulted in turbulent shear changing periodically, which was generated by the current velocity. The periodical turbulent shear changing affected the flocs diameter, so the quasiperiods of flocs diameter was close to that of current velocity.

Key words: spectrum analysis, grain size, flocs, LISST, Changjiang Estuary, Xuliujin