Organic Characteristics And Dynamic Sedimentation Of Suspended Matter And Its Biogeochemical Behavior In The Changjiang Estuary

Using FACScan flow cytometer, this thesis has studied the suspended matters of the Changjiang Estuary for the first time. The reality of measuring the distinction of the composition of suspended matters has been proved, and the distribution of organic matters on mineral particles and the characteristics of organic coating matters of the Changjiang estuary have been given.Using the cytometer and the scanning electromicroscope, the author has analyzed and observed the characteristics of biology and chemistry of suspended matters. The results show that organic related particles account for 60% to 75% of total particle numbers of suspended matters. The composition of the particles in order of the size is the clay, mineral of organic sticking, organic coating materials and organic matters; the flocculation of suspended matters is mainly conducted by organic materials.By studying the sources and composition of suspended matter of the Changjiang Estuary, it is realized that there are two types of suspended matters with different organic matter: marine pattern and fluvial pattern. The organic matters on surface of particles are major carriers for transporting metals and its surface characteristics have significant effects on flocculation, sedimentation, resuspension and transportation of suspended matter. The composition changes of suspended matters conducted by water masses and estuarine physical processes are main factors to make intense changes of physical and chemical parameter of estuary.Based on the analysis of dynamic sedimentation of suspended organic related matters in Changjiang Estuary, barocline, water density change and tide pump at turbidity maximum (TM) are main reasons for TM forming and the reasons of fluid mud forming and selective transporting of silt. They also conduct the aggregation, flocculation, sedimentation and re-suspension of the organic related particles at TM. The organic related particles have important contribution for enhancing the suspended matter viscosity and against flow shear.According to the understanding of suspended organic related particles on above, the biogeochemical characteristics are studied and the distribution model of time-space of biogeochemical processes in the Changjiang Estuary is given. The concentration distribution of organic related particles indicates the concentration distributions of POC, PON and POP. The Changjiang river mouth can be divided into three regions: weak degradation (river section), strong degradation (TM ) and photosynthesis ( plume area). Finally, the biogeochemical cycling model of organic related particles is put forward.