| The sediment in aquatic environment is not only the main media for organic pollutants to transport and transform, but also playing an important role in environmental fate and bioavailability, which also closely related to the human life. In addition, the pollutants sorption, degradation and transport on the sediment will have an important effects on their behavior and fate in aquatic environment, furthermore, these processes are connected and influenced to each other.With the scientific advances and growing environmental pollution, persistent organic pollutants become more hot spot involving in their environmental bebavior research. Organochlorine pesticides (OCPs) are mostly used as insecticides and mainly include HCH and DDT, in addition, nine organochlorine pesticides are listed in the prefered controlled POPs. Lanzhou actually has a long history for using these two OCPs and the OCPs of Yellow River in Lanzhou mainly come from the waste water of agricultural pesticide use and the emissions of enterprises production to rain. The behavior and fate of OCPs in the aquatic environment are influenced by degradation, sorption, desorption and transport processes. Therefore, to study the sorption and desorption behaviors has a significant theoretical worth for understanding their environmental fate, assessing the ecological risk and water pollution control in the study area.In this shesis, we chooseγ-HCH and p,p'-DDT as the representative of OCPs to study the characteristics for sorption and desorption of typical persistent organic pollutants by using the cleaner sediments of up Yellow River in Lanzhou as the sorbent.Meanwhile, different characteristics of sorption and desorption on the humic acid and montmorillonite were also investigated. The proper model was used to fit the sorption dynamics data ofγ-HCH and p,p'-DDT on the sorbents and the sorption velocities were also determined. In addition, Henry,Fruendlich and Langmuir model were used to fit thermodynamic date, and tried to figure out the differences and similarities of the sorption behaviors on different sorbent. The study results are summarized as follows:(1) All kinetic sorption behaviors ofγ-HCH and p,p'-DDT on sediments, the humic acids and montmorillonites exhibited distinguished two stages:fast and slow. The sorption amount ofγ-HCH and p,p'-DDT were increased with increasing time and the contact time of 12-14h was sufficient for sediments, humic acids and montmorillonites to achieve equilibrium. In addition, the sorption velocities ofγ-HCH and p,p'-DDT were faster on humic acids and montmorillonites than those on sediments. The sorption and desorption processes happened simultaneously at the procedure of sorption of pesticides, and the sorption rates were higher than that of desorption, which indicated that the desorption was delayed and the pollutants can transported over a long distance in aquatic environment.(2) The study results also showed that Henry,Fruendlich and Langmuirthe model were all fitted for describing the sorption behavior ofγ-HCH and p,p'-DDT on the sediments in the study concentrations range, which exhibited the complicacy of sorption behavior of these two compounds. Furthermore, Henry model was better for sorption ofγ-HCH and p,p'-DDT on humic acids and montmorillonites by comparing the different correlation coefficient. In addition, from the study results we deduced that the sorption capability of p,p'-DDT onto sorbents was stronger than that ofγ-HCH. and the sorption capability on different sorbents from large to small as follows:forγ-HCH, humic acids> montmorillonites>surface sediments; for p,p'-DDT, montmorillonites> humic acids>surface sediments, which indicated the more humic acid and clay mineral content in sediment would result in the stronger sorption capacity of sediment.(3) In this paper, the effects of some influence factors on sorption behaviors including initial concentration of sorbate and sorbent, water temperature, pH and so on were also invastigated by using orthogonal experimental design. The study results showed that different sorbents did not have the significant effect on the sorption amounts per unit of y-HCH. Furthermore, the initial concentration of sorbate and sorbent were obviously very to the sorption of p,p'-DDT on surface sediments, which exhibited a positive correlation in sorbates and a negative correlation in sorbents. Moreover, the sorption of p,p'-DDT on humic acids and montmorillonites were related with the concentration of sorbent, and other effects of temperature, pH, granularity of sediments and content of organic matter were observed in this paper.
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