Occurrence Of Sulfonamides And Their Acetylated Metabolites In The Typical Wastewater Treatment Plants And Receiving Rivers At The Pearl River Delta And Biological Toxicity Research

In recent years,large quantities of drugs and personal care products?PPCPs?have remained in the environment.China is a major producer of antibiotics,and sulfonamides?SAs?are widely used in human health and disease control.The underutilized sulfonamides antibiotics enter the sewage treatment system through urine,fecal excretion,etc.,and the existing sewage treatment technology cannot completely remove them.The final residual SAs are concentrated in the natural water body near the wastewater treatment plants,which may have a certain potential impact on the aquatic environment and microorganisms of the Pearl River.Therefore,this project aims to study the occurrence and biological toxicity of sulfonamides and its metabolites in urban wastewater treatment plants and rivers in the Pearl River Delta.Pearl River Delta and the corresponding discharge rivers during the dry and wet seasons.The optimized solid phase extraction-high performance liquid chromatography method was used to qualitatively and quantitatively determine the target SAs,and analyze their occurrence as well as the removal efficiency in the sewage plant.Based on the actual environmental concentration levels,the hazard quotients?HQs?were calculated by the SAs residues detected to evaluate the potential ecotoxicological risk towards three aquatic organisms?algae,fish and daphnia?.Finally,the acute biological toxicity effects of SAs to the luminescent bacteria were tested.The main conclusions of this study are as follows:?1?Sulfadiazine?SDZ?,sulfapyridine?SPY?,and sulfamethoxazole?SMX?are detected frequently and at relatively high concentrations in wastewater treatment plants,especially during the dry season.Among them,the maximum concentrations of SDZ and SMX in the influents were 216 ng/L and 200 ng/L,respectively.?2?Municipal wastewater treatment plants have a degradation efficiency of more than 50%for most sulfonamide targets.In addition,the ubiquitous conversion of SAs parent compounds and acetylated metabolites in wastewater treatment plants will affect the accurate assessment of removal efficiency.A method of jointly evaluating parent compounds and corresponding acetylated metabolites may be considered.What's more,the existing secondary biological treatment processes of most urban sewage plants can not completely remove the SAs pollutants,and the residual pollutants discharged from the final effluents into the nearby receiving rivers should not be neglected.?3?Most SAs did not have serious potential harm to environmental microorganisms,except for three substances:SDZ?SMZ and SMX.Among them,either in the effluent of urban sewage plants or the nearby rivers,SMX had great potential adverse effect to the seaweed,and its HQ value was beyond 3.6.?4?Acute biotoxicity experiments showed that the effect of different mass concentrations of SAs on the photobacterium phosphoreum T₃ was that as the increase of SAs concentrations,the inhibitory effect on the luminescence of photobacterium phosphoreum was gradually enhanced,presenting a classic S-type dose response curve.In addition,the acute toxicity of different SAs on different organisms was also different.The biological toxicity of6 SAs to the photobacterium phosphoreum was ranked as follows:sulfamethoxazole?SMX?>N⁴-acetylsulfadiazine?ACSDZ?>N⁴-acetylsulfamethazine?ACSMZ?>N⁴-acetylsulfamethoxazole?ACSMX?>sulfapyridine?SPY?>sulfadiazine?SDZ?.