1、1Transformation Mechanism of Nitrobenzene in Groundwater and Soil and its Simulation and ForecastAbstract： Through indoor simulation experiment， this paper determines the main factors influenced the migration and transformation in aquifer， and calculate the influence degree of these factors by analy
2、tic method. Research shows that the adsorption capacity of nitrobenzene in silt medium greater than in sand medium， the block coefficient of silt medium was 2.22， block coefficient and sand medium was 1.74. Based on the first-order kinetic equation， respective of silt medium natural decay rate const
3、ant is 0.0644/h， sand medium natural decay rate constant is 0.0056/h. Keywords： Nitrobenzene； Soil； Ultrasonic Extraction； Residue Dynamics 0 Introduction Nitrobenzene is carcinogenic， mutagenic toxic organic pollutants， which is listed as the EPA， the EC and Chinas environmental priority pollutants
4、. As a defense， printing， plastics， pesticides and pharmaceutical raw materials and intermediates， mass production and widespread application of 2nitrobenzene caused serious pollution to the environment. currently， nitrobenzene adsorption studies focused on agricultural soil， forest soil by surfacta
5、nt-modified soil or marine sediments， its environment the distribution， migration and transformation as well as harm the environment today is one of the hot scientific basic research. Many data show that only accurate grasp of nitrobenzene features and changes affecting their respective environmenta
6、l factors， in order to make a scientific assessment of nitrobenzene in the environment， transport and transformation processes and destination. To this end， the international community in many developed countries have invested a lot of manpower， material and characteristics of nitrobenzene， all aspe
7、cts of pollution status， environmental transport and transformation behavior， ecological toxicity carried out basic and applied research 2， including nitro volatilization of benzene in the air， water， soil and other media， adsorption， biodegradation， abiotic degradation studies （hydrolysis， photolys
8、is， etc.） as well as other environmental bioaccumulation behavior . And our research in this area is lagging behind， relevant background information with foreign countries there is a certain gap. In our long-term 3monitoring of groundwater quality， almost no separate analysis of nitrobenzene， charac
9、teristics related to groundwater migration and transformation of nitrobenzene and its behavior in the underground environment is not enough to understand . Currently， according to foreign literature search showed 2， environmental behavior of nitrobenzene research focuses on atmospheric and surface w
10、ater， and more to handle contains high concentrations of organic wastewater nitrobenzene goal， about the low levels of nitrate benzene in the underground environment， migration and transformation of quantitative research is also unusual. In this paper， by conducting laboratory simulation experiments
11、 to determine the main factors influencing the migration of nitrobenzene in the aquifer conversion and mining Calculated using the analytical solution methods affect the level of each factor， migration and transformation to establish a mathematical model of nitrobenzene foundation . 1 Nitrobenzene m
12、igration and transformation mechanism in aquifer Nitrobenzene into the aqueous layer may be mainly through the following procedure ： （1） The aqueous layer was adsorbed media particles ； （2） to the surface volatilization ； （3） 4biodegradable ； （4） non-biodegradable （ hydrolysis ， photolysis， oxidatio
13、n reduction reaction， etc. ） ； （5） to be absorbed into the food chain enrichment plant or degradation. Environmental behavior of organic pollutants in aquifers is first determined by its own nature， such as hydrophobicity， volatility and stability. At the same time ， environmental factors also have
14、an important impact， such as the composition and structure of the aquifer medium aquifer microbial activity ， organic matter content and chemical composition of groundwater . Based on the current literature reports that： nitrobenzene not hydrolysis ， and in vivo accumulation of small， easy to zoom t
15、hrough the food chain . Moreover， migration and transformation for nitrobenzene underground environment， are less likely to occur photolysis ， its volatile impact （20， 20 Pa） can be ignored. Therefore ， adsorption and biodegradation are the main factors affecting the migration of nitrobenzene in the
16、 aquifer transformation. According to migration and transformation of nitrobenzene influencing factors to consider convection ， diffusion ， adsorption and biodegradation， that establish for nitrobenzene a one-dimensional mathematical model of migration and 5transformation in the aquifer below ： Wher
17、e： C is the concentration of nitrobenzene in water （ML-3） ；Sis the soil adsorption concentration of nitrobenzene （MM-1） ；x is vertical migration distance in groundwater （L） ；Dx is vertical diffusion coefficient （L2T-1） ；vx is longitudinal velocity of groundwater （LT-1） ；dis the volume of dry bulk de
18、nsity of the aqueous medium （ML-3） ；nis the porosity， dimensionless； is the rate constant for the biodegradation （T-1）. In the formula （1）：is dispersion term， is convection term， is adsorption items， is biodegradable items， It is assumed that water， the same soil degradation rate of nitrobenzene. According to the results of laboratory simulation experiments， using analytical solution methods are needed to determine the temporal parameters of the above model， combined with the actual study initial and boundary conditions can be obtained aquifer nitrobenzene concentration distribution.
