[Effect of soil organic matter and cadmium (II) on adsorption and desorption of chlortetracycline in soil].

ABSTRACT

Chlortetracycline (CTC) has been widely used in veterinary medicines and disease treatment. Heavy metals and antibiotics often coexist in soil due to land application of animal wastes and other sources of inputs. On the basis of the OECD Guideline 106, the batch equilibrium experimental method was employed to investigate sorption and desorption processes of CTC in cinnamon soil with and without soil organic matter (SOM) and examine the effect of Cd2+ on these processes. Results showed that the Freundlich model was the best isotherm to describe the experimental data for adsorption and desorption of CTC in soil on single and combined pollution conditions. In these a single chlortetracycline pollution and chlortetracycline-Cd combined pollution conditions, removal of SOM could increase the CTC adsorption capacity (K(f)) and adsorption intensity (1/n). The apparent adsorption-desorption hysteresis was found in cinnamon soil with and without SOM. In single pollution condition, the removal of SOM could significantly increase HI in cinnamon soil from 0.81 to 1.06. In all cases of CTC combined with Cd desorption studies, it had been known that HI of CTC in soils with SOM (1.11) were higher than those without SOM (0.84). This study was provided available data and parameters to set a more complete model to predict environmental concentration of CTC and evaluation their environmental risk.