[Degradation and bioaccumulation characteristics of ciprofloxacin in soil-vegetable system]

A pot experiment was conducted to investigate the effects of applying ciprofloxacin (CIP) on the growth of flowering Chinese cabbage (Brassica campestris), radish (Raphanus sativus), tomato (Solanum lycopersicum) and long bean (Vigna unguiculata), the bioaccumation of CIP in the vegetables, and the degradation of the antibiotics in soil. The results showed that applying 5, 30 and 75 mg x kg(-1) of CIP had no significant effects on the plant biomass of flowering Chinese cabbage, tomato and long bean, but the high concentration of CIP (> or = 30 mg x kg(-1)) inhibited the radish growth significantly. The degradation of CIP in soil was fast at beginning, but slowed down gradually since then. The DT50 and DT90 of CIP in long bean soil were 18.3-43.9 d and 260-738 d, respectively. The CIP could be absorbed by the roots of all the four vegetables and allocated to their aboveground parts, and the CIP residues in the vegetables in creased with the concentration of CIP in soil. The CIP concentration in flowering Chinese cabbage roots was higher than that in the cabbage aboveground parts, that in radish showed a higher concentration in aboveground parts than in roots, and the CIP concentration in tomato and long bean was in the same order of root > stem > leaf.