Adsorption and Hydrolysis Characteristics of Antibiotics in the Hyporheic Zone of Zaohe-Weihe River, China

Abstract

To reveal the attenuation characteristics of antibiotics in completely different physical and chemical environments formed when surface water and groundwater complement each other, this paper selected the hyporheic zone of Zaohe-Weihe rivers as the study area, explored the adsorption and hydrolysis behavior of oxytetracycline (OTC), norfloxacin (NOR) and sulfamethoxazole (SMZ) by simulating the hyporheic zone. Results showed that the maximum adsorption capacity of the three antibiotics on sediment was SMZ (1008.14 mg/kg)>OTC (430.03 mg/kg)>NOR (128.47 mg/kg). The adsorption processes all were consistent with the Freundlich model. The hydrolysis rate of the three antibiotics in surface water was 2-10 times that in groundwater. In surface water, the half-lives of the three antibiotics were OTC (9.75 d)>SMZ (11.2 d)>NOR (14.2 d), respectively. In groundwater, the half-lives were OTC (14.78 d)>NOR (63.59 d)>SMZ (117.48 d), respectively. The hydrolysis rate of the three antibiotics under alkaline conditions was significantly greater than acidic and neutral conditions. High temperature and the adding of sediment or clay were conducive to the hydrolysis of antibiotics.