Effect Of Dissolved Organic Matter On Photodegradation Of Acenaphthene Under Different Conditions In Water And Ice

With the convening of the Third Plenary Session of the 18th CPC Central Committee,China has officially entered the 2.0 era.China’s current economy is developing at an amazing speed,and China has become the largest industrial country in the world.And followed by all kinds of industrial waste gas emissions,a large number of fossil fuel combustion,and improper handling of poisonous and harmful waste,produce a large amount of Hydrophobic Organic Contaminants（HOCs）in the environment,and one of PAHs belongs to the persistent organic pollutants（pops）,with the"three to effect"of its own and biological toxicity,and because of its difficult degradability and long-distance migration,can accumulate in any environment medium,and cause inconvenient to human survival environment.Most of the Dissolved organic matter（DOM）comes from the remains of plants and animals or the organic matter with very complex composition and structure formed by the decomposition of plants and microorganisms,which plays a vital role in the carbon cycle of the earth and the regulation of the ecosystem.At present,the photochemical degradation of HOCs in water has received great attention and research,but the degradation mechanism of pollutants in ice phase has been neglected.Compared with the fluid atmosphere,water and other environmental media,the physical migration process,routine chemical reaction and microbial action of pollutants in the ice body are relatively weak,but the photochemical action shows a significant effect.At the same time,the aquatic environment complex nature,often caused by pollution and so on water body composition is varied,the different environment with ice water phase,and the DOM on degradation of PAHs light influence will not only help to understand the natural water ice water phase in the photochemical properties of DOM,and understand the carbon biogeochemical also under cold environment is of great significance.This article covers two types of DOM:Abstract:Using Suwannee River NOM（SRNOM）and Upper Mississippi River NOM（UMRNOM）water source DOM and Acenaphthene,the representative of typical polycyclic aromatic hydrocarbons（PAHs）,as the research object,simulated photolysis experiments were conducted in laboratory using 500W long arc xenon lamp as the simulated light source.The spectral characteristic parameters and the binding constant(K_DOC)between the two kinds of DOM and Acenaphthene at different p H before and after freezing-thawing were investigated.The effect of DOM on the photolysis of acenaphthene under different p H conditions in ice phase and water phase was studied by the apparent photolysis rate constant(K_OBS)of acenaphthene,and the correlation analysis was carried out.The effects of dissolved organic matter on Acenaphthene photolysis in ice-water phase under different p H conditions were obtained by high performance liquid chromatography,ultraviolet spectrum and synchronous fluorescence method.The results are as follows:Acenaphthene can be photodegraded directly in both ice phase and water phase,and the rate of direct photolysis in ice phase is slightly increased.At the same time,the photodegradation of acenaphthene by the two kinds of DOM in ice phase and water phase had a certain promotion effect.On the whole,different DOM has different effects on the photodegradation of pollutants in ice and water phase.In the aqueous phase,with the increase of p H,the photolysis promotion of acenaphthene produced by the two DOM will be continuously enhanced.However,in the ice phase,the change of p H did not have the same significant effect on the promotion as in the water phase,and the promotion decreased overall in the ice phase.At the same time,two DOM after freezing and thawing process,its own spectroscopy parameters appeared the same trend of change,SUVA and E₂/E₃significantly enhance are appeared,the rise of p H in not freeze-thaw samples can cause a certain spectral characteristic parameters,and that there was a significant correlation between the both and in freezing and thawing processing samples p H change trend did not appear this kind of influence.In the binding effect of DOM and Acenaphthene and photoquenching method,the binding ability of both DOM and Acenaphthene before or after freeze-thaw treatment was affected by the change of p H.With the increase of p H value,the binding ability of DOM to acenaphthene decreased.Compared with the sample without freeze-thaw,the binding constant of the freeze-thaw treated sample will decrease to a certain extent.In the process of ultraviolet index analysis,the apparent photolysis rate constant of acenaphthene in water phase was significantly correlated with both DOM binding constants and spectral characteristic parameters in the coexistence with DOM,while the apparent photolysis rate constant of acenaphthene in ice phase was only significantly correlated with binding constants and had no correlation with other parameters.This suggests that photochemical reactions in ice may have a more complex mechanism.