采用批平衡实验方法,研究了氧四环素(oxytetracycline, OTC)在褐土、红壤与森林土壤中的吸附/解吸行为,同时以大肠埃希菌(Escherichia coli ATCC 25922, E. coli ATCC 25922)作为实验菌株,研究了土壤吸附态的氧四环素的生物活性。结果表明, Freundlich和Langmuir模型均可以对OTC在三种土壤中的吸附和解吸曲线数据进行良好的拟合, OTC 在褐土中的吸附/解吸等温线呈线性,而在红壤与森林土壤中的吸附/解吸等温线呈非线性,且 Langmuir 方程拟合效果优于 Freundlich 方程。OTC 在三种土壤上的解吸过程均存在明显的滞后性。土壤吸附态抗生素对细菌生长的抑制作用表明, OTC与土壤发生吸附作用之后,依然具有生物有效性。
This study investigated the adsorption and desorption of OTC in three different soils by using batch equilibrium tests, and assessed the biological activity of soil-adsorbed OTC by using E.coli ATCC 25922 as the experimental strain. The results showed that the data of adsorption and desorption for OTC on all soils were well fitted with both Freundlich and Langmuir models. Both adsorption and desorption isotherms of OTC on the Cinnamon soil were linear, while those for the Forest soil and Red soil were nonlinear. The Langmuir model gave better fitting than Freundlich model for all three soils. An adsorption-desorption hysteresis phenomenon was observed in all the three soils. The bioavailability experiments with E. coli showed that the adsorbed OTC was still active against bacteria.