Atmospheric Lifetime Study Of Hexachloro-1,3-butadiene Based On Observation And Simulation

Hexachloro-1,3-butadiene(Hexachloro-1,3-butadiene,HCBD)is a persistent organic pollutant(POPs)with toxic,bioaccumulative,persistent,long-distance transport and other dangerous characteristics.Its emissions in China have risen far beyond other countries and has been detected in living organisms,so it has gradually gained attention.Hexachloro-1,3-butadiene belongs to VOCs and can be quickly volatilized into the atmosphere from water surfaces and moist soils.The content in the atmosphere is much higher than other media,so the study of hexachloro-1,3-butadiene's atmospheric transformation process and residence time are of great significance.Based on the research background,the subject chooses the atmospheric lifetime of hexachloro-1,3-butadiene as the research object.In the past,the calculation process for the calculation of the atmospheric lifetime of hexachloro-1,3-butadiene was rough and not accurate enough.In this study,the reaction mechanism of hexachloro-1,3-butadiene and the mechanism of Cl gas phase chemical reaction were added to the MCM gas phase chemical reaction mechanism.Based on the BOXMOX chemical chamber model,we build a box model which can simulate the concentration of hexachloro-1,3-butadiene and the reaction process.With the constraints of online monitoring data and other physical meteorological data,the relevant free radical concentration and the atmospheric lifetime of hexachloro-1,3-butadiene can be simulated and calculated in the BOXMOX atmospheric chemical reaction boxmox model.According to the model simulation,hexachloro-1,3-butadiene is degraded by OH radicals to account for 80-90%of its total consumption,and hexachloro-1,3-butane consumed by Cl radicals for about 10-20%,while the total consumption of hexachloro-1,3-butadiene by NO3,HO2,and O3 is less than 0.001%.It can be considered that the reaction of hexachloro-1.3-butadiene with OH radicals is dominant,the reaction with Cl radicals is secondary,and the degree of reaction with NO3,HO2,O3 is extremely low.Through the simulation and calculation of the atmospheric lifetime of hexachloro-1,3-butadiene,it is believed that the atmospheric lifetime of hexachloro-1,3-butadiene is about 1.76 years with the pollution level in eastern China.The reaction rate constant of hexachloro-1,3-butadiene oxidized by OH radical has a great influence on its atmospheric lifetime estimation.Secondly,the presence or absence of Cl reaction mechanism and continuous concentration of CINO2 concentration in the model simulates atmospheric life.It also has a large effect;the influence of CINO2 concentration is slightly smaller;the calculation of photolysis rate constant and the continuous constraint of N2O5 concentration have little effect on the simulation of hexachloro-1,3-butadiene atmospheric life;the height of boundary layer in the model is taken The values of the values and TUV model parameters have little effect on the simulation of each free radical concentration and the calculation of atmospheric lifetime,which is negligible.In this study,an atmospheric chemical reaction box model was constructed to simulate the concentration of HCBD and the reaction process.The model was used to simulate the concentration of each radical and calculate hexachloro-1,3-butadiene's atmospheric lifetime under various simulated conditions.The atmospheric lifetime of HCBD in accordance with the pollution conditions in eastern China was determined by analysis,and the influence of various simulation conditions on the atmospheric lifetime of HCBD was given,which provided a reliable basis for future decision-making and treatment programs.