Variation and accumulation characteristics of diazepam in simulated culture environment

In order to explore the degradation and accumulation characteristics of diazepam (DZP) in simulated culture environment, we set up four experimental groups including two different concentration stress groups (Group A and Group C) and two control groups (Group B and Group D) with addition of Pteris vittata to analyze the changes of DZP content in water, sediment and P. vittata with time, and to investigate the accumulation characteristics of DZP in water by P. vittata and sediment. The results show that the initial DZP mass concentrations in Group A, Group B, Group C and Group D were (0.118±0.002) μg·L⁻¹, (0.117±0.004) μg·L⁻¹, (1.141±0.078) μg·L⁻¹ and (1.142±0.039) μg·L⁻¹, respectively. The DZP concentration had decreased by 29.71%–40.17% after 768 h, and the degradation half-life period of DZP ranged from 65.29 d to 139.11 d. The DZP concentration in the sediment in the four groups increased gradually with time, reaching 17.99 times (1.384 μg·kg⁻¹, dry mass), 14.81 times (0.918 μg·kg⁻¹, dry mass), 4.77 times (7.848 μg·kg⁻¹, dry mass) and 5.30 times (7.763 μg·kg⁻¹, dry mass) of the initial concentration after 768 h of administration, respectively. The enrichment coefficients were 9.79–18.80. The peak concentration of DZP in Group B and Group D appeared after 216 h after administration. The adsorption and enrichment of DZP in water by P. vittata and the sediment can obviously shorten the degradation half-life period of high concentration DZP in water, and addition of P. vittata to low concentration DZP can inhibit the enrichment of DZP in sediment.