The Environmental Behavior Of Several Typical Organic Pollutants

Triazine herbicides are widely used as a selective herbicide to control broadleaf and grassy weeds on com, sorghum, orchards, pineapple and several other crops. It has been found that they have caused serious pollution in heavily used area. The study on physical chemistry and biochemistry behaviors of atrazine, simazine, prometryne, prometon, cyanazine and ametryne was carried out. According to the content, it consists of two segments mostly. The first segment investigates the physio-chemical behavior of triazine in environment. The primary conclusions obtained are listed as follows: (1) The sorption triazine herbicides are studied on humic acids and soils. The results showed that all the isotherms of these herbicides could obey Freundlich equation very well. Adsorption extent of these six herbicides increased in an order of cyanazine< atrazine< simazine< prometon< prometryne< ametryne, which was determined by the structure of substituting group of traizine in the molecule. This order is same to the calculation result of excess thermodynamic properties of triazine. (2) The adsorption of herbicides on 4 kinds of soil colloids was measured by 4 -potential measurements. From the point of zero charge (pzc), we have calculated adsorption constants and Gibbs energies and compared them with binding constants determined by batch equilibration technique. The results are similar, showing that the C -potential technique can be useful in a study of the herbicides adsorptions on soil colloids. (3) A chemiluminescence suppression method for the determination of catalase based on Luminol-KIO4-H2O2-catalase system was established. (4) The influence of herbicides on catalase activities is discussed. The six herbicides have similar influent process on catalase activities, "stimulation, recover and stabilization". The activity of catalase was stimulated by concentration of triazine, with the stronger influence observed at higher concentration. Stimulation extent of these six herbicides increased in an order of cyanazine< atrazine< simazine< prometon< prometryne< ametryne. (5) The binding characteristics of herbicids to catalase have been investigated by using florescence and UV difference spectroscopy. Based on the site binding model and florescence quenching, the equilibrium constants and number ofbinding sites for triazine herbicides interacting with catalase were measured by florescence method. The transfer efficiency energy and distance between herbicides and catalase were obtained in view of the theory of Foster energy transfer. Further more, the interaction between herbicides and enzyme was studied using by ζ -potential measurements and HPLC with microdialysis sampling technique.It was reported recently that the triazine herbicides were rapidly dechlorinated in water solution by polysulfides and the reaction mechanism was suggested to be nucleophilic aromatic substitution (SnAt) reaction. In this study, the kinetics and mechanism of reaction between polysulfides and triazine herbicides were investigated. Common inhibitors, oxygen and benzoquinone, remarkably decreased the reaction speed. Compared with the reaction rate constant p. in air (0.0953 mM-1 h-1) , the reaction rate constant increased more than 2 times in nitrogen (0.2144 mM-1 h-1). The u decreased about 50% compared to the control when 360 uM benzoquinone was added into the polysulfide solution. The negative effect of radical inhibitors suggests that free radicals were directly involved in the reaction. From the ESR spectra, it was found that the radical concentration in polysulfide solution decreased about 85% after reacting with triazine herbicides. These observations together suggest that the reaction might occur by radical nucleophilic substitution (Srn1) in which the herbicide undergoes a free radical chain reaction that dechlorinates the herbicide.Synthetic pyrethroids (SPs) are widely used insecticides in both agricultural and urban environments. Most SPs have high acute toxicity to fish and aquatic invertebrates. On the other hand, SPs are kno...