Distribution Of Typical Antibotics In The Aquatic Environment Of The River

With the rapid development of pharmaceuticals, antibiotics have beenwidely used in medicine, farming and breeding.Despite of great contribution in preventing disease, guaranteeing human health and promotingagriculture,fish breeding and poultryraising, the overuse of anticbiotics has brought many environmental problems and exerted potential detriments to our human beings. The overdose of antibiotics may cause several hazards such as side effects, superinfection, allergic reactions and drug resistance. Varieties of antibioticscould enter the aquatic environment in the form of prototypes or metabolic intermediates, and contaminated the watereventually. Recently, antibiotics have been detected successively in surface water, groundwater and sediment scattering around all continents, with their concentrations up to several nanogram per liter. A lot of research about pollution profiles of various antibiotics has been carried out, and some achievements have been made. However, studies aboutdistribution of various antibiotics in water, particulates and sediments in both the mainstream and branches of a river valleyare still insufficient.Therefore, it is very helpful and of significance to investigate the comprehensive distribution of antibiotics, for it is the foundation of proper ecological risk assessment. This work focused on the pollution profiles and distribution characteristics of antibioticsin a typical river valley.First of all, reliable and stable methods were established for the determination of 21 antibiotics（including 11 SAs, 7 FQs, 2 MLs, 1 CHLO） in matrices like surface water, particulate matter and sediments in a typical river valley in this work. Then the pollution profiles and distribution characteristics of antibiotics in urban and suburb areain this valley were studied. 1. Stable methods were developed and validated for determination of the antibiotics in aqueous environmental using ultra-high performance liquid chromatography-tandem mass spectrometry. These antibiotics were extracted by solid phase extraction（SPE） with HLB cartridges. The extraction recoveries were in the range of 69.0%^-115.0% in pure water. And the LODs of the target antibiotics were in rang of 0.02ng·L^-1-2.27ng·L^-1 in thesurface. The relative standard deviations for precision and reproduction were within 10%. 2. After optimizing the extractant, volume and extraction time, 21 target antibiotics in par-ticulate matter and sediments were extracted by Ultrasonic extraction. SPE was applied toconcentrate antibiotics by optimizing p H condition, washing and eluting solutions, andSAX-HLB was used to cleanup. The extraction recoveries were in the range of 61%-96% in sediments. The LODs were in rang of 1.36ng·g^-1-4.05ng·g^-1 in the solid phase. The rel- ative standard deviation was in rang of 2^-10%. 3. Using the above methods, the distribution of 21 target antibiotics in water and sediment in the upstream of the valley was investigated during August and January, 2014. A variety of antibiotics were detected, and the main concentration was up to several hundred ng·L^-1. In dissolved phase, concentration of four groups of antibiotics followed the descending order, SAs>FQs>MLs>CHLO. The highest total concentration of target antibiotics is 818.22ng·L^-1 and 846.03 ng·L^-1 in dry season and wet period, respectively, with sulfonamidesand macrolides as the dominant species, while in particulate matter, the highest total con-centrations were 312.23 ng·L^-1 and 380.20 ng·L^-1 in dry season and wet period, respec-tively. In Addition, in sediment samples, the highest total concentrations were 552.60ng·g^-1 and 812.20 ng·g^-1, respectively, with fluoroquinolones and macrolides as the dom-inant species. 4. Meanwhile, the distribution of 21 target antibiotics in water and sediment in downstreamof the valley（Shaoguan to Guangzhou） was also investigated in May, 2014. Fourteenkinds of antibiotics were detected in this segments in which the total concentrations of theaqueous phase, particulate matter and sediment were 943.02 ng·L^-1, 308.31 ng·g^-1 and664.38 ng·g^-1,respectively.