An Investigation Of Microplastics Of Juhe And Study On The Effects Of Microplastics On Degradation Of Phenanthrene By Fusant Strain F14

As a kind of durably organic pollutants,Polycyclic Aromatic Hydrocarbons(PAHs)existed widely in nature.Microorganism degradation is an important way to remove PAHs and other organic pollutants in the environment.Recently,microplastics(MPs)in the environment have attracted more attention,due to their smaller size,containing potentially harmful additives(flame retardants,antioxidants,etc.),or due to their rough surface and hydrophobicity,they are very easy to adsorb other pollutants and as the carrier of pollutants.MPs in the environment not only adsorb pollutants,but also affect the microorganism metabolism and the removal of pollutants.At present,most research on microplastics focus on the marine environment,while there are few studies on inland rivers and lakes.This article first investigated the pollution of microplastics in a river in Shanxi Province(Juhe).Then,the influence of two kinds of microplastics(polyethylene(PE)and polystyrene(PS))on the PAHs bacterium F14(fusant strain)and the degradation effect of phenanthrene were studied.Finally,a simulation experiment of actual soil pollution was carried out.The main findings are as follows:(1)The situation of MPs pollution in the Inland River-Juhe River Basin of Linfen City(Shanxi Province,China)was studied.The results showed that:the concentration of MPs in the surface waters varied from 35 to 124 n·L^-1and the MPs content with particle size of 1 to 5mm is the most.in the sediments,the abundance of MPs varied from 32.22 to 118.06 n·kg^-1and the MPS content less than 0.1 mm is the most.There are four main shapes:membranous,flaky,fibrous and globular,among which the fragmental shape has the highest content,and the globular shape has the lowest content.The surface of MPs is rough and has different degrees of scratches,in which the surface of fibrous and spherical MPs is relatively worn seriously.the surface of MPs contains a lot of C and O elements,as well as a small amount of Cl,Si,Fe,Al and other elements.there are mainly PE(polyethylene),PP(polypropylene),PS(polystyrene)and PVC(polyvinyl chloride)polymers.(2)The effect of polyethylene microplastics(PE-MPs)on the degradation of phenanthrene by Fusant Strain F14 were examined.Scan electron microscopy(SEM)analysis showed obvious depressions in the cell and the concentration of extracellular polymeric substances increased significantly after the addition of PE-MPs.The results of the Fourier transform infrared spectroscopy(FTIR)spectroscopy used to characterize the chemical composition of the cell surface showed that after exposure to PE-MPs,the absorption intensities of carbohydrates,polysaccharides,and amides on the surfaces of the cells in the strains changed,and the relative contents of protein,nucleic acid,and polysaccharides increased significantly.The cell reactive oxygen species(ROS)test showed that with the increase in the concentration of PE-MPs and the extension of culture time,the reactive oxygen content in the F14 cells gradually decreased.The PE-MPs particle sizes had no significant effect on the production of ROS in cells.(3)The effect of Polyethylene Microplastics(PS-MPs)on the degradation of phenanthrene by the Fusant Strain F14 were examined.SEM analysis showed obvious depressions or even damage in the cell and the concentration of extracellular polymeric substances increased significantly after the addition of PS-MPs.The results of the FTIR spectroscopy used to characterize the chemical composition of the cell surface showed that after exposure to PS-MPs,the absorption intensities of carbohydrates,polysaccharides,and amides on the surfaces of the cells in the strains changed.At the initial stage,the relative contents of protein and nucleic acid increased significantly,while the absorption intensity of the characteristic peaks of polysaccharide decreased,and there was no significant change at the later stage.The cell ROS test showed that with the increase in the concentration of PS-MPs and the extension of culture time,the reactive oxygen content in the F14 cells gradually increased.The smaller the particle size,the greater the degree of damage,but did not cause serious damage to F14 strain.(4)The effect of PE-MPs on the remediation of contaminated soil by F14 strain were simulated.The results showed that the degradation products of F14 strain and phenanthrene would adhere to the surface of PE-MPs,increasing the surface O/C ratio of MPs.1 mm PE–MPs had no obvious effect,but 500?m PE-MPs inhibited the degradation effect more obviously with the increase of concentration.The results of FDA enzyme activity and TOC showed that PE-MPs affected the remediation of phenanthrene contaminated soil by F14 in the following two ways:First,change the soil structure,affect the activity of F14 strain,and change the degradation rate of phenanthrene.Second change the soil organic carbon content,affect the adsorption of phenanthrene,and then affect the degradation rate of phenanthrene by F14 strain.