Riverine transport dynamics of PBDEs and OPFRs within a typical e-waste recycling zone: Implications for sink-source interconversion

•Dissolved PBDEs and OPFRs were concentrated in porewater and overlying water.•Sediment is interchanged with sink and source for riverine transport of OPFRs.•Sediment-water diffusion of PBDEs and OPFRs was not significant compared to riverine transport. Despite ample evidence on spreading of e-waste derived hazardous materials, riverine transport of organic contaminants from e-waste recycling zones to surrounding areas has not been evaluated. To address this issue, passive and grab sampling methods were used to assess sediment-water diffusion and horizontal transport of polybrominated diphenyl ethers (PBDEs) and organophosphorus flame retardant (OPFRs) at upstream and downstream sites of two rivers in a typical e-waste recycling zone. Sediment acted as a source of BDE-17 with fluxes of 0.007−0.04 ng m−2 d−1 at all sampling sites. BDE-47 and BDE-99 reached equilibrium between overlying water and sediment porewater. Sediment interconverted from a sink at the upstream site to a source of OPFRs at the downstream site with a flux varying between −7.3 and 234 ng m−2 d−1. The amounts of OPFRs (11−45 g d−1) via horizontal riverine transport were greater than those of PBDEs (0.68−2 g d−1). The vertical sediment-water diffusion of PBDEs and OPFRs was not significant compared to horizontal riverine transport. The annual riverine outputs of PBDEs and OPFRs from the downstream sites were 250–330 g and 12,000–16,500 g, respectively, indicating the significance of riverine transport of organic contaminants from e-waste recycling zones to surrounding areas. [Display omitted]