Hydrobiogeochemistry and Pollution Control Laboratory, Department of Environmental Sciences, Jahangirnagar University, Dhaka 1342, Bangladesh; Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia.
Hydrobiogeochemistry and Pollution Control Laboratory, Department of Environmental Sciences, Jahangirnagar University, Dhaka 1342, Bangladesh.
Sci Total Environ. 2024 Jul 20;935:173346. doi: 10.1016/j.scitotenv.2024.173346. Epub 2024 May 21.
Antibiotics, one of the significant emerging contaminants, are intensifying their continual spread out into the environment and affecting human health and the ecosystem in the developing country Bangladesh. This study characterizes widely used fluoroquinolone (FQ) antibiotics, formulates the method to spectrally distinguish them from ubiquitous, and important reactive, adsorbent, and altering catalytic macromolecule humic substances (HS), and further quantifies them using fluorescence spectroscopy. The presence of identical fluorophore at Excitation/Emission = 225-230/285-295 nm wavelength, possession of fluorescence spectra at short emission wavelength (<350 nm) during 275 nm excitation, different emission maxima, and various fluorescing components in antibiotics identified through three-dimensional excitation-emission matrix (EEM) and parallel factor analysis (PARAFAC) models distinguished them from the humic substance as well as from each other. Stern-Volmer equation and its modified version were applied to identify quenching and binding capability, and fluorescence intensity quenching rate of antibiotics and humic in their mixture. Unlike poor and inconsistent quenching mechanisms of humic, FQ antibiotics reduced HS intensity throughout the entire photo-irradiation experiment affirming the functioning of the stable quenching methods. Static quenching of fluorophores was identified from the redshift of excited wavelength on the electronic ground state. Temperature differences during daylight and dark conditions played contrasting roles during the fluorescence quenching of FQ. Unique spectral response at emission wavelength < 350 nm during 275 nm excitation in FQ was considered as its least intensity in the antibiotic-humic mixture and was also used to formulate distinct spectral pattern of each FQ antibiotic. The study also identified the traces of FQ antibiotics with various intensities at different lakes in Bangladesh.
抗生素是一种重要的新兴污染物，其在环境中的持续扩散加剧，并对发展中国家孟加拉国的人类健康和生态系统产生影响。本研究对广泛使用的氟喹诺酮（FQ）抗生素进行了特征描述，制定了从普遍存在的重要反应性、吸附性和改变催化性的大分子腐殖质（HS）中对其进行光谱区分的方法，并进一步使用荧光光谱法对其进行定量。在 275nm 激发下，具有相同荧光团（激发/发射波长=225-230/285-295nm）、在较短发射波长（<350nm）下具有荧光光谱、不同发射最大值以及抗生素中具有不同荧光成分的物质，可通过三维激发-发射矩阵（EEM）和平行因子分析（PARAFAC）模型与腐殖质以及彼此区分开来。Stern-Volmer 方程及其修正版本被用于识别抗生素和腐殖质混合物中的猝灭和结合能力以及荧光强度猝灭率。与腐殖质较差且不一致的猝灭机制不同，FQ 抗生素在整个光辐照实验中降低了 HS 的强度，证实了稳定猝灭方法的有效性。荧光团的静态猝灭是从电子基态激发波长的红移确定的。在 FQ 的荧光猝灭中，白天和黑夜的温度差异扮演了相反的角色。在 275nm 激发下，<350nm 处的独特发射波长的光谱响应被认为是抗生素-腐殖质混合物中其最低强度的原因，也用于制定每种 FQ 抗生素的独特光谱模式。该研究还在孟加拉国的不同湖泊中检测到了具有不同强度的 FQ 抗生素的痕迹。
