Fig. 2

Concentrations (histogram) and degradation rates (line chart) of tetracycline (a) and sulfadiazine (b) in different layers of soil MFCs. The average concentrations and degradation rates of antibiotics (c). Different lowercase letters represent significant differences at the 0.05 level among TC, TO and TN or SC, SO and SN, respectively. The closed-circuit, open-circuit and non-electrode treatments spiked with tetracycline were, respectively, labelled as TC, TO and TN; those spiked with sulfadiazine were, respectively, labelled as SC, SO and SN