四环素和土霉素在Cu污染土壤中的吸附和解吸特征

Adsorption-desorption of Tetracycline and Oxytetracycline in Cu Contaminated Soil

采用间歇平衡震荡法,研究四环素和土霉素在清洁及Cu污染黑土和潮土中的吸附和解吸特征.结果表明,供试土壤对四环素和土霉素均具有很强的吸附能力.四环素在黑土和潮土中的吸附容量(Kd)值分别为4198.83和3741.99L·kg-1,高于土霉素相应Kd值1399.50和224.9 L·kg-1.此外,2种四环素类抗生素在土壤中均存在一定的滞后性,滞后性强弱顺序为潮土中土霉素>黑土中土霉素>潮土中四环素>黑土中四环素.重金属Cu的存在会促进抗生素在土壤中的吸附,并且在黑土中对抗生素吸附促进作用强于潮土.在Cu污染土壤中四环素和土霉素的解吸同样存在一定的滞后现象.四环素在两种土壤中的滞后系数随着土壤Cu浓度的增大而逐渐减小,土霉素在潮土中的滞后系数逐渐增大,而在黑土中先增大后减小.

The adsorption and desorption of tetracycline and oxytetracycline in clean and Cu contaminated soils were studied by batch equilibration method.The results showed that tetracycline and oxytetracycline were highly adsorbed by the two soils.The adsorption capacity(Kd)values of tetracycline in black soil and tidal soil were 4198.83 L·kg-1 and 3741.99 L·kg-1,respectively,higher than oxytetracycline which were 1399.50 L·kg-1 and 224.9 L·kg-1,respectively.Desorption hysteresis of tetracycline antibiotics was also observed,and the order of hysteresis index(HI)was:Oxytetracycline in tidal soil>oxytetracycline in black soil>tetracycline in tidal soil>tetracycline in black soil.The presence of Cu promoted the adsorption of antibiotics in the soil,and the influences of antibiotics adsorption in black soil were stronger than those in tidal soil.The desorption of tetracycline and oxytetracycline also showed the hysteresis in Cu co-contaminated soils.The HI of tetracycline in the two soils decreased gradually with the increase of copper concentration,and the HI values of oxytetracycline increased in tidal soil,and increased when the Cu concentration was below 1000μg·g-1and then decreased in black soil.