Assessment of Pyrethroid Accumulation and Compartmental Distribution in a Zebrafish-Myriophyllum Spicatum Aquatic Microcosm Using Oleic Acid-embedded Cellulose Acetate Membranes

Pyrethroids (PYRs) frequently occur in aquatic environments, but their distribution and accumulation in multi-compartment systems remain poorly understood. Permethrin (Per), fenpropathrin (Fen), and bifenthrin (Bif) were investigated in a 21-day water–sediment-zebrafish ( Danio rerio )- Myriophyllum spicatum microcosm. Per was added to water, whereas Per, Fen, and Bif were separately added to sediment. Concentrations in oleic acid-embedded cellulose acetate membranes (OECAMs) were converted to equivalent aqueous exposure concentrations using compound-specific OECAM-water partition coefficients. These values were used to derive apparent bioconcentration factors (BCFs) for zebrafish and accumulation factors for M. spicatum during the late exposure phase. At 504 h, sediment accounted for 58.46% of recovered Per in the water-spiked treatment, while zebrafish and M. spicatum accounted for 18.46% and 17.16%, respectively. In the sediment-spiked treatments, 99.43%-99.87% of recovered PYRs remained in sediment. After correction for pesticide removed by repeated sampling, recoverable parent mass decreased by 67.90% in the water-spiked treatment and by 27.64%-39.27% in the sediment-spiked treatments. OECAM-normalized apparent BCFs ranged from 389.31 to 970.11 L kg −1 wet weight in zebrafish, while accumulation factors ranged from 262.94 to 769.58 L kg −1 wet weight in M. spicatum . The OECAM-derived metric provided an exposure-related basis for interpreting organism accumulation under dynamic aqueous conditions, particularly when conventional water measurements became limited by low concentrations.