| In this thesis, cross-flow ultrafiltration techniques have been used to determine and systematically study the concentration, distribution and controlling factors of colloidal nutritious material in Changjiang river estuary and its adjacent area. In addition, the changes of colloidal nutritious material were investigated and discussed in the presence of marine biological activity in the blooming seawater culture system and the shrimp (Penaeus chinensis) culture system. The main results read as follows: I Concentrations of inorganic nutrients, size-fractionated dissolved organic C, N and dissolved organic P in the Changjiang river estuary and its adjacent area were determined.1. The recoveries of cross-flow ultrafiltration system were calculated by mass balance experiments. Except to organic P, no significant contamination or loss during ultrafiltration were observed and inorganic nutrients and dissolved organic C, N can be quantitatively recovered.2. The influences of ultrafiltration on inorganic nutrients were different, phosphate and silicate can somewhat interact with colloidal particles, and the interaction ability of silicate was a little smaller.3. Concentration of dissolved organic N was higher in summer than in winter. CON accounted for about 10% of DON. Concentration of DOP in summer was about the same to that in winter. Concentrations of size-fractionated organic carbon in summer were much higher than those in winter, and their vertical distribution mostly decreased from surface to bottom. The COC/DOC% in summer and winter ranged from 9.0% to 28.8%. COC and DOC distributed linearly, the coefficients in the summer and winter were 0.28 and 0.17 respectively. The distribution of size-fractionated organic carbon in summer and winter were mainly controlled by physical mixing process of Changjiangriver fresh water input. C/N ratios in COM were higher than in DOM and UOM in the studied region.II Through the field experiment with Skeletonema costatum blooming seawater, concentrations of inorganic nutrients, size-fractionated dissolved organic C, N were determined.1. Mass balance experiment showed no significant contamination or loss of inorganic nutrients and dissolved organic C, N during ultrafiltration.2. COC concentrations reached their maxium value 1 day later than DOC and UOC, and is the most active part in the DOC. DON, UON and CON in the control bottle didn't have evident trend in the degradation of bloom, while in the adding-nutrients bottle increased slowly since the nutrients were added. In both bottles during the experiment, CON accounted for less than 10% of DON.III Inorganic nutrients and size-fractionated dissolved organic C, N and P were determined in process of the shrimp( Penaeus chinensis) culture experiment.1. From mass balance experiment, there were not significant contamination or loss occurred to inorganic nutrients and dissolved organic C, N, P during ultrafiltration.2. Diurnal change of inorganic nutrients seemed well-regulated. In the continual observation of 7 days, the deviation coefficient was smaller than that in the diurnal observation. Phosphate and ammonia accumulated, while nitrate and nitrite didn't change evidently in the continual experiment of 7days.3. Diurnal change of CON was a little different from those of DON and UON. In the continual observation, size-fractionated dissolved organic N and P had similar trend with their inorganic counterparts. DOC, UOC and COC fluctuated drastically in a day, COC was the most active part in DOC. In the continual observation of 7 days, DOC, UOC and COC increased slowly with time. COC/DOC ratio in shrimp culture ecosystem was much higher than that in natural seawater. Diurnal change of C/N ratio in size-fractionated organic material was similar to that of size-fracitonated organic carbon, the C/N ratio in COM and its deviation coefficient were most high. In continualobservation of 7 days, C/N ratio in size-fractionated organic material didn't have evident trend, and their devi...
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