Effect Of Dissolved Organic Matter (DOM) On Adsorption Of Atrazine On Black Soil And Mechanism Analysis

Black soil in Northeast China is a very important part of resources to protect food safety in China.The black soil region in Northeast China is one of the three major black soil regions in the world.Its characteristics are high fertility,high organic matter content,superior physical and chemical properties,and suitable for cultivation.So black soil resources are also rare natural resources in the world.Black soil region is the main grain producing area in China.The crops planted not only meet the needs of the people,but also achieve economic income generation.However,in recent years,due to the extensive application of pesticides such as pesticides and herbicides,and the degradation of black soil is very prominent.The main problem is the excessive use of pesticides and fertilizers.So many difficulties that need to be solved urgently have brought great harm to food security and environmental safety in China,and have more opportunities to pollute the environment and damage the ecosystem.Generally speaking,to protect the safety of black soil in Northeast China is to maintain food safety in China.Atrazine is often used as a triazine herbicide in farmland soil.Because of its low cost,good weed control and weed removal effect,it has been widely used in maize,sorghum,sugarcane and other crops.However,the addition of atrazine in the soil system will inevitably bring some negative effects on the organic whole of farmland soil.Atrazine can also produce lethal toxicity to the central nervous system of advanced animals.Atrazine can be detected in many environmental media,such as soil,surface water and groundwater,and its concentration level is higher than i ts maximum allowable limit.In order to prevent atrazine from toxicity to human body,it is necessary to study the migration,transformation and distribution of atrazine in the solid phase of farmland soil.Based on the above practical background,this thesis explores the migration and transformation of atrazine in black soil,and uses the dissolved organic matter(DOM)extracted from black soil to further study the adsorption and removal behavior of atrazine in black soil.Finally,the experimental process was characterized by various fluorescence spectroscopy methods.The main results are summarized as follows:Adsorption behavior of atrazine and dissolved organic matter(DOM)extracted from black soil in black soil was studied in this experiment.The experimental data showed that the two kinds of samples were soil + dissolved organic matter group and soil group.Their adsorption capacities were 41.80 and 31.45 mg kg-1,respectively.Through calculation,the adsorption capacity of dissolved organic matter was 9.35 mg kg-1.The results showed that dissolved organic matter could significantly increase the adsorption rate of atrazine in black soil.At the same time,the data show that the pseudo-second-order kinetic model can better explain the adsorption process.Secondly,according to the results of adsorption isotherm equation(R2 > 0.99),the adsorption behavior can be described by both Langmuir model and Freundlich model.In this study,the interaction between dissolved organic matter and atrazine was analyzed by various spectral methods,including three-dimensional excitation emission matrix(3D-EEM),synchronous fluorescence,two-dimensional fluorescence spectrum(2D-COS)and Fourier transform infrared spectroscopy(FT-IR).The results of three-dimensional fluorescence spectroscopy showed that the main component of dissolved organic matter was humic-like substances.The data of synchronous fluorescence spectrum show that static quenching is the most important quenching process in the whole quenching behavior.Two-dimensional spectra show that the order of spectral transformation is 336 nm > 282 nm.In addition,in the atrazine environment,the fluorescence quenching of humic-like part appeared earlier than that of protein-like part.Fourier transform infrared spectroscopy showed that the main components of dissolved organic matter were protein,polysaccharide and humic acid.This paper reveals that dissolved organic matter plays an important role in its adsorption behavior with atrazine black soil,and provide s some new ideas for studying the relationship between dissolved organic matter and herbicides by spectroscopy.In this paper,atrazine is widely used in farmland in China,which results in serious soil pollution.Considering its interaction with dissolved organic matter,atrazine was selected as the target pollutant in this paper.In order to study the complex composition of dissolved organic matter,fluorescence spectroscopy is used as a sensitive method for effective analysis.The adsorption behavior and mechanism of atrazine in black soil were discussed by various adsorption model theories and spectral characterization methods,and the role of dissolved organic matter in the process of atrazine adsorption on black soil was also discussed.Generally speak ing,dissolved organic matter plays an important role in the adsorption behavior of atrazine on black soil,and it also provides some new ideas to study the relationship between dissolved organic matter and herbicides by spectroscopy.Through the above tests and analysis,this paper can lay a foundation for the restoration of contaminated black soil,make the application of atrazine more rational,and have great significance for alleviating the damaged black soil ecological environment.