Study On The Relationship Between Sediment And Heavy Metal Pollution From Typical Bend In Chongqing Region Of Three Gorges Reservoir

With the interception of the Three Gorges Reservoir(TGR), the hydrology in TGRhas been changed and the Sedimentation volume has been increased. Due to theinfluence of the special water movement in typical bend, Settlement of sediment isbecoming easier. The existing form and the space-time distribution rule of Heavy metalpollutants will be changed in TGR. Therefore, the study of the relationship betweensediment and heavy metal pollutants from typical bend in Chongqing region of TGR hasthe important theoretical and practical value.The sediment concentration and Pb,Cd concentration in natural water whichcollected from typical bend in Chongqing region of TGR is monitored on-site based onmonitoring data of main sections in Chongqing region of TGR, give preliminaryanalysis of the temporal and spatial variation of sediment concentration and Pb,Cdconcentration in natural water, learn the basic situation which sediment impact on heavymetal from typical bend in natural water. Afterwords, the experimental data has beenfitted by Lagergren pseudo-first order kinetics, quasi-second-order kinetic model andHenry, Freundlich, Langmuir, Temkin adsorption isotherm models based on theexperiment of adsorption kinetics and adsorption thermodynamics, which obtain theadsorption law of sediment from typical bend in Chongqing region of TGR.The results turns out that: The sedimentation and sediment discharge distributed inflood reason and the Chongqing region of TGR has been polluted by Lead and cadmiumwithin flood season; The sediment in Huang Huacheng is dominated by the finesediment which is smaller than0.025mm, and the fine sediment accounted the totalweight for72%to90%, the overall size of the sediment showed a decreasing trendalong the way. Sediment concentration is one of the main factors that determine thecontent of heavy metals in natural waters, sediment Contribution rate to Pb of thenatural water is53%~59%, sediment Contribution rate to Cd of the natural water is34%~43%. In addition, when the sediment concentration increases with depth change,Pb, Cd concentrations of the natural water showed an increasing trend; Under thepremise of constant water environment (pH7to8, the water temperature is18.5℃, theaqueous phase Pb,Cd initial concentration is2.0mg/L), sediment for Pb, Cd adsorptionequilibrium time decreases with the increase of sediment concentration; Lead adsorptioncapacity is much greater than the ability of sediment adsorption of cadmium, per unit mass of sediment on the adsorption capacity of lead cadmium is2to3times; Under thecondition which is the different sediment concentrations and different initialconcentrations of Pb,Cd, Lagergren pseudo-second order kinetic model is better thanLagergren pseudo-first order kinetic model which would describe the Pb,Cd adsorptionkinetics curve of sediment from typical bend in Chongqing region of TGR; Under thepremise of constant water environment (pH7to8, the water temperature is18.5℃, theaqueous phase Pb,Cd initial concentration is2.0mg/L). For thermodynamic adsorptionstate is concerned, Freundlich adsorption isotherm is better able to describe theadsorption behavior of Pb sediment isothermal behavior. Langmuir adsorption isothermis better able to describe the adsorption behavior of Cd sediment isothermal behavior.