水中四环素类化合物在不同光源下的光降解研究.doc

水中四环素类化合物在不同光源下的光降解研究在模拟太阳光照射下均能发生直接光降解降解速率随pH不同变化很大。四环素TC）、土霉素OTC）、金霉素CTC）和多西环素DTC）的光降解速率随溶液pH升高明显加快，而米诺环素MTC）在水中的光降解速率随溶液pH升高略有下降。降解半衰期在(136 min范围内关键词 Hu Xuexiang Chen Yong Hu Chun* Nie Yulun (Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085) Abstract The aquatic photochemical behaviors of tetracyclines (TCs) were investigated under the simulated and natural sunlight. The results indicated that TCs directly degraded under the simulated sunlight. Moreover, the TCs’ photodegradation efficiency changed as the solution pH. The photodegradation of tetra cycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), and doxycycline (DTC) increased with the increase of pH, whereas the minocycline (MTC) photodegradation exhibited different trend. In the pH range of natural water, the reaction rate constants of TCs ranged from 0.004~0.026 min-1, and the half-lives of photodegradation of TCs ranged from 26~136 min under simulated sunlight. The direct photodegradation rate of TCs is proportional to the sunlight intensity. Photolysis of TCs under sunlight irradiation at different season showed that the degradation is faster in the summer compared with that in the spring/winter. The photodegradation of tetracycline in Dongjiang River showed a fast rate. The average half-lives of TC was 8.2 min in clear weather of winter. Key words direct photolysis；tetracycline；natural sunlight；simulated light；half-lives of photodegradation 四环素类抗生素具有广谱性、质优价廉的特点，目前已经成为我国畜禽饲养业中生产量和临床使用量最大的抗生素[]。其中以四环素、土霉素和金霉素在实际应用过程中应用最广泛、使用量最大[]。四环素类抗生素水溶性较好，经体内代谢大部分以原形排出[]，最终进入城市的污水处理系统(中，而各种污水处理过程对污水中的这些物质不起作用或作用很少，最终被排放到境中，对环境污染构成潜在威胁。它们在环境中不易发生生物降解，因而容易在水环境中储存和蓄积[4]，它们在地表水中已被频繁检出[57]。同时，作为广谱抗生素,它们在水环境中的长期广泛存在可能威胁微生物群落，并诱导耐药菌株的产生[8-11]，其环境行为越来越受到重视。因此，有必要评价它们在水体中的环境化学行为。 辐射到地球表面的太阳光是一个连续光谱。在天然水体表层，太阳光辐射可以导致许多有机分子发生光化学反应12-14]。光化学降解是药物在水环境中常见的转化途径。对天然水体中有机污染物降解起决定作用的是波长在290-400nm的可见光，可以分为UV-A区320-360nm)和UV-B区290-320nm)[15]。本文本文研究了四环素类抗生素在模拟太阳光及室外太阳光照射下的光降解行为，为更准确的