Bioavailability assessment of propiconazole to Limnobium laevigatum and zebrafish (Danio rerio) in aquatic microcosms

Abstract

Residues of the triazole fungicide propiconazole (PCZ) in the environment can easily enter aquatic ecosystems through various pathways and accumulate in sediments, thus threatening ecosystem stability. The method of using passive sampling techniques to measure the freely dissolved concentration (C_free) of pollutants in aquatic environments for assessing their bioavailability has been widely utilized in environmental risk assessments. This study employs oleic acid-embedded cellulose acetate membrane (OECAM) as a tool to determine the C_free of PCZ in water. By establishing sediment spiking concentrations of 0.1 and 0.5 mg/kg in an aquatic microcosm, the distribution and bioaccumulation of PCZ in zebrafish (Danio rerio) and the aquatic plant Limnobium laevigatum (L. laevigatum) were examined over a 7-day period. During the experimental period, the concentrations of PCZ in the water for the 0.1 mg/kg and 0.5 mg/kg treatment groups remained approximately 0.9 μg/L and 10.0 μg/L, respectively. After 7 days, the PCZ content in the sediments decreased by 22.74% and 14.94%, respectively. In both zebrafish and L. laevigatum, the concentration of PCZ initially increased and then gradually stabilized, with both species exhibiting moderate accumulation ability for PCZ. The bioconcentration factor (BCF) for zebrafish in the 0.1 mg/kg and 0.5 mg/kg treatment groups ranged from 9.25 to 13.96 and 7.84–16.05, respectively, while those for L. laevigatum ranged from 28.17 to 31.40 and 23.01–36.11, respectively. By the end of the 7-day experiment, the total PCZ content in both treatment groups decreased by an average of 17.51%. Among them, L. laevigatum contributed significantly, highlighting its potential in accelerating the removal of PCZ from aquatic ecosystems.