Preliminary Study Of The Mixing Process Of Phosphorus, Silicon In The Yangtze Estuary

The migration and transformation of nutrients in the estuary is not only theimportant one of the biogeochemical processes, but also one of the importantprocesses of influencing and controlling the nutrient flux transporting from estuary toocean.To explore the mechanism,which is that the environmental factors influenceon the nutrient dilution mode, it not only need field investigation, but also need toanalyze and summarize the results of each factor in the lab,so that it has an accuratedescription and a profound understanding of nutrition elements，dilution in the Yangtzeestuary. At the same time, the key process of offshore eutrophication and the drivingaction of the east china sea algal blooms disasters are understood.In this study，effects of （T,pH,S,DO） on change pattern of mixing process of yangtze runofffreshwater and east china sea external seawater were examed combining with realdilution of nutrients of The Yangtze estuary and adjacent sea areas Diluted Water. Theinfluence of main water environmental factors of the Yangtze estuary on Nutritionelements in the estuary of mixed behavior is studied system and comprehensive.Conclusions were summarized as follows:（1）As simulation experiment shows,PO₄-P, SiO₃-Si concentration basically unchangedafter15hours of mixing of seawater and the Yangtze river water.There is littledifference that PO₄-P concentration and SiO₃-Si concentration with the trend of thesalinity between mixture of filtered Yangtze river water and seawater and unstrainedYangtze river water and seawater in25℃,because Chlorinated mercury inhibit biologicaldisturbances or the Yangtze river water which we took contains less particles.（2）mixture of seawater and the Yangtze river water, the concentration of PO₄-Pchange little when the temperature is from10to20℃, in low salinity area,and PO₄-Pconcentration increases with the temperatur from20to30℃and decaeses with thetemperatur from30to35℃. SiO₃-Si concentration is slightly increases withtemperature increased when the temperature is10℃to35℃. PO₄-P concentrationreduces when pH is from4to6and unchanged basically when pH from6to8andincreases when pH is from8to10in low salinity area. PO₄-P concentration increaseswhen pH is from4to6and unchanged basically when pH from6to8and decaeseswhen pH is from8to10in high salinity area. SiO₃-Si concentration unchangedbasically minxing of Yangtze river and seawater in different pH period. SiO₃-Siconcentration unchanges when pH is from4to8and increases with pH from8and10.PO₄-P, SiO₃-Si concentration reduces with salinity increased in anoxia and richoxygen state and there is no significant difference of the states. PO₄-P concentration ishigher in anoxia than rich oxygen state.（3）Field investigation shows, PO₄-P concentration decreases in the whole salinityrange and with the salinity increased in the four seasons and there are certain bufferrole. SiO₃-Si concentration have a good correlation with salinity in spring, autumn and winter and it is agree with simulation experiment. The Yangtze estuary andadjacent sea areas of salinity from0to18, simulation experiments and fieldinvestigation have a consistent in the temperature of15-30℃.SiO₃-Si concentrationincreases with increased temperature in summer （200607）, PO₄-P concentrationbasically unchanged increased with the pH from7.8to8.2, and simulation experimentare in agreement. SiO₃-Si concentration basically unchanged increased with the pHfrom7.7to7.9PO₄-P, SiO₃-Si concentration in the whole range DO basicallyunchanged.The Yangtze estuary and adjacent sea areas of salinity from18to33,PO₄-P, SiO₃-Si concentration unchanged with temperature from10to15℃inWinter（200612） and PO₄-P concentration increases with temperature from20to25℃in summer（200607）, they are agree with simulation experiment.PO₄-P, SiO₃-Siconcentration in spring（200704） and summer（200607）, PO₄-P, SiO₃-Si concentrationincreased with the pH reduced, high DO concentration is low PO₄-P concentration,low DO is high PO₄-P concentration in spring （200704） summer （200607）, SiO₃-Siconcentration and DO are active related, in autumn （200710） and winter （200612）,mainly by physical mixed effect.