Occurrence, Bioaccumulation, and Biomagnification of Organophosphate Flame Retardants in Aquatic and Terrestrial Food Chains from a Former E-Waste Recycling Region, South China

Organophosphate flame retardants (PFRs) have increasingly substituted legacy brominated flame retardants, yet their bioaccumulation and trophic transfer across coupled aquatic–terrestrial food webs remain poorly understood. The present study investigated the occurrence, bioaccumulation, and biomagnification of 15 PFRs in abiotic (water, sediment, and soil) and biotic (vegetation, invertebrates, and vertebrates) compartments from a former e-waste recycling region in South China. Average ΣPFRs concentrations ranged from 2.64 to 23.2 ng/g wet weight (ww) in organisms, dominated by tris(2-chloroisopropyl) phosphate, triphenyl phosphate, tris-n-butyl phosphate, and tris(2-chloroethyl) phosphate. Most PFRs showed limited bioaccumulation potential, with bioaccumulation factors (BAFs) and biota-sediment/soil accumulation factors of 1.12–5426 L/kg and 0.00299–23.7, respectively. While ΣPFRs underwent biodilution across all four aquatic–terrestrial food chains, congener-specific biomagnification was observed. Significantly positive correlations were observed between log octanol–water partition coefficients (log Kow) and log BAFs in aquatic species and terrestrial plants, while negative correlations appeared between log Kow and biomagnification factors, indicating that the bioaccumulation of PFRs is co-driven by the moderate lipophilicity of congeners and efficient biotransformation in high-trophic-level predators. These findings highlight the divergent trophic transfer of PFRs across aquatic–terrestrial ecotones, providing key insights for ecological risk assessment in post-e-waste recycling environments.