Sorption–Desorption of Typical Tetracyclines on Different Soils: Environment Hazards Analysis with Partition Coefficients and Hysteresis Index

Abstract

Abstract

To evaluate environment hazards of tetracyclines (TCs) on different soils from the north of China, desorption hysteresis index and partition coefficients (K_d) were obtained by sorption–desorption experiments. Five different soils, including black soil (BLA), cinnamon soil (CIN), cultivated loessial soil (CUL), castanozems, and brown soil (BRO), were collected to test the sorption–desorption properties of oxytetracycline (OTC). Molecular properties of TC, chlortetracycline (CTC), and OTC were acquired by quantum chemistry calculations to explain the sorption–desorption differences on CUL. Among the five soils, BLA exhibits strongest adsorption of OTC and the adsorption follows the order of BLA>CIN≈BRO>CUL≈CAS, and the hysteresis index (HI) has an opposite trend at low contamination levels. Among the TCs investigated, sorption follows the order of CTC>TC>OTC on CUL, which is determined by both molecular polarity and steric hindrance. The order of HI is OTC>TC>CTC on CUL. It was found that CUL is most sensitive to TCs' contamination among the five soils and OTC is most labile to induce environment hazards considering its lower K_d than CTC and TC. This work will help researchers in identifying the most sensitive soil to TCs' contamination, the most dangerous compound among TCs, and the origin of sorption difference, and thus to ameliorate or avoid potential environment hazards of TCs.