Behavior of PAEs in coastal mangroves: Transfer in sediment-water interface and bioaccumulation in aquatic food web (Dongzhai Harbor, Hainan Island, China)

This study integrated MixSimmr-based food web mixing matrices with the fugacity model to quantify PAEs diffusion across the sediment-water interface and trophic bioaccumulation in Dongzhai Harbor mangroves (Hainan, China) and elucidated their linkage. Results showed that the fugacity fraction (ff) gradually decreased with the increase of carbon-chain length and molecular weight of PAEs, and PAEs with high-molecular-weight were more inclined to transfer and enrich into the sediment. Rapidly exchanged and highly water-soluble dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP) entered organisms via gill respiration, whereas slowly exchanged and poorly soluble di-2-ethylhexyl phthalate (DEHP) accumulated through food intake. The transfer kinetics of PAEs across the sediment-water interface govern their uptake route into organisms. However, this relationship was modulated by species-specific feeding habits and the physicochemical properties of individual PAEs. Fish with distinct feeding habits exhibited divergent PAEs accumulation and degradation. Highly hydrophobic PAEs adsorbed onto sediments are more prone to biomagnification through predation by benthic or demersal carnivorous and omnivorous fish. Among various degradation pathways, the highly soluble DMP is primarily eliminated through gill respiration, whereas DEP, DBP, BBP, and DEHP are mainly removed via excretion. The metabolic half-lives of PAEs within organisms increased with increasing octanol-water partition coefficient (K_OW) value. These findings offer critical insights for conserving mangrove ecosystems and guiding sustainable resource use. SYNOPSIS: PAEs, global emerging pollutants, enter mangroves via runoff and deposition, then adsorb and transfer within the ecosystem. This study employed models to explore the transfer of PAEs in mangrove ecosystem.