Photo-modified Toxicity Of Typical New Pollutants Polycyclic Aromatic Hydrocarbon Derivatives And Antibiotics

Polycyclic aromatic hydrocarbon derivatives(SPAHs)are a class of ubiquitous new pollutants with widespread sources and hidden risks.SPAHs can be transformed from polycyclic aromatic hydrocarbons(PAHs)through microbial and chemical reactions,and they are even more toxic than their parent PAHs.Antibiotics have been continuously discharged into the water environment because of their abuse behavior,and become a new kind of "pseudo-persistent" pollutants.These new organic pollutants are constantly detected in the environment,which has aroused wide concern.Photochemical degradation is an important transformation pathway of these new organic pollutants on the surface of water,snow and ice.It is of great significance to study their photomodified toxicity and photoconversion risk.Therefore,in this thesis 10 SPAHs(4 hydroxy-PAHs(OH-PAHs),3 nitro-PAHs(N-PAHs)and 3 chlorinated PAHs(Cl-PAHs))and 16 antibiotics(9 sulfonamides antibiotics(SAs),4 cephalosporin antibiotics(CFs),3 macrolide antibiotics(MLs))were selected to research their photochemical behavior and photoconversion risk in pure water or water ice.The photodegradation of 10 SPAHs in water/ice phases was investigated under simulated sunlight irradiation.The results showed that all the 10 SPAHs were photodegraded in water and ice phases,and the degradation reaction followed the quasi-primary reaction kinetics,and the photodegradation rates of the three types of SPAHs were different in water and ice phases.Using HPLC-MS/MS,the photoproducts of 1-hydroxynaphthalene was identified and the reaction path was speculated.The photo-modified toxicity of these typical SPAHs to Vibrio fischeri was investigated in pure water and ice systems.Toxicity tests indicated that the two OH-PAHs 1-hydroxynaphthalene and 4-chloro-1hydroxynaphthalene showed significant photo-modified toxicity in water and ice,while 4-nitro-1-hydroxynaphthalene only exhibited minor photo-modified toxicity in water phase.For N-PAHs,1-nitropyrene showed photo-modified toxicity in both water and ice phases,while the photo-modified toxicity of 2-nitrofluorene to Vibrio fischeri was observed only in ice.Among Cl-PAHs,only 1-chloropyrene presented photo-modified toxicity in water,while all the three Cl-PAHs showed significant photo-modified toxicity in ice.The photodegradation of SAs in water under simulated sunlight was investigated.The results indicated that all the 9 kinds of SAs can be photodegraded and obey the quasi-primary reaction kinetics.At the same time,the antibacterial activity of 9 SAs to E.coli and the evolution trend of photoproducts were also investigated.The results showed that,antibacterial activity of 9 SAs to E.coli decreased,but some photoproducts had stronger antibacterial activity during sunlight irradiation.By HPLC analysis,the 9 SAs produced a variety of photoproducts,and their products have different generation and evolution trends.The chromatographic peak area of most of the photoproducts will increase with the sunlight irradiation,that means,these products will accumulate with the extension of irradiation time.There are also some photoproducts of the chromatographic peak area fluctuated or flattened,that means,these products also have photoreactive activity,can be photodegraded.By HPLC-MS/MS analysis,the photodegradation paths of SAs containing five-and sixmembered heterocyclic rings were different.In order to further reveal the photo-modified toxicity of new organic pollutants.Further examines the photo-modified toxicity of 16 kinds of antibiotics to luminescent bacteria Vibrio fischeri.The results showed that 4 of the 9 SAs produced photoproducts with higher toxicity than the parent compounds in the process of photolysis,showing stronger photo-modified toxicity.four SAs showed weak photomodified toxicity;one SAs showed no photo-modified toxicity.Among the 4 CFs,cefoxitin and cefazolin produced photoproducts with high risk,showing strong photo-modified toxicity.Cefthiophene and cefoperazone photoproducts has similar toxicity to the parent compounds.Compared with the other two classes of antibiotics,the parent compounds of 3 MLs showed higher luminescence inhibition to Vibrio fischeri,and all showed photo-modified toxicity under irradiation.In summary,the results of this study elucidate the rules and differences of phototoxicity of typical PAHs derivatives and antibiotics.It is helpful to evaluate the photochemical transformation risk of these typical new pollutants more accurately in surface water and provide scientific basis for their ecological risk assessment.