地表水中典型磺胺类抗生素的自然衰减

近年来,磺胺类抗生素因大量使用,在河流等地表水中广泛检出,其环境行为及生态危害,成为备受关注的环境问题.本文以10种常见磺胺类抗生素为研究对象,通过微宇宙实验,模拟其在河流表层水中的自然衰减规律,同时模拟直接光降解、间接光降解、水解、细菌降解和微生物降解等多种条件,以阐明不同环境因素对磺胺类抗生素自然衰减的作用机制.结果显示,10种磺胺类抗生素在168 h内的自然衰减率可达55%—100%,半衰期为14.7—115.5 h,表明磺胺类抗生素在进入河流等地表水后可发生自然衰减.结构方程模型分析表明,直接光降解及间接光降解是磺胺类抗生素自然衰减的主要途径,而水解和微生物降解的作用不大.采用高分辨率质谱,共检出7种降解产物,推测磺胺类抗生素的转化路径主要包括N—S键断裂及羟基化作用.ECOSAR毒性分析结果表明,转化产物毒性多低于母体抗生素,但仍可能存在潜在的环境风险,需进一步深入研究.

Natural attenuation behavior of typical sulfonamides in the surface water

Due to its extensive usage and frequent detection in the surface water,the environmental behavior and ecological toxicity of sulfonamides have received increasing concerns.This study investigated the attenuation pattern and factors influencing the natural attenuation of 10 typical sulfonamides by simulating hydrolysis,direct and indirect photolysis,bacterial degradation and microbial degradation in microcosm.The results showed that 55%to 100%of sulfonamides could be removed under natural attenuation with the half-life from 14.7 h to 115.5 h,which indicated the sulfonamides can be naturally attenuated after entering the river surface water.The structural equation modeling approach demonstrated that the direct and indirect photolysis were the major factors contributing to the natural attenuation of sulfonamides,while hydrolysis,bacterial degradation,and microbial degradation were not effective.Seven transformation products were identified by high resolution mass spectrometry,which suggested that the sulfonamides attenuation mainly occurred through N-S cleavage and hydroxylation.The toxicity evaluation based on ECOSAR showed that the toxicity of the transformation products was lower than the parent compounds.However,the transformation products might still have potential environmental risks and further studies should be conducted.