Spatiotemporal distribution and mass loading of organophosphate flame retardants (OPFRs) in the Yellow River of China (Henan segment)

During three sampling periods in 2014, systematic investigations were conducted into contamination profiles of ten organophosphate flame retardants (OPFRs) in both suspended particulate phase and water phase in the Yellow River (Henan Area). This research shows that OPFRs exist at lower concentrations in the suspended phase than in the water phase. The median concentration of 10 OPFRs (∑₁₀OPFRs) in the suspended particulate phase was 62.5 ng/g (fluctuating from ND to 6.17 × 10³ ng/g, dw), while their median concentration in the water phase was 109 ng/L (fluctuating from 35.6 to 469 ng/L). Among the selected 10 OPFRs, triethylphosphate (TEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(2-chloroethyl) phosphate (TCEP) were the predominant compounds in the water phase (occupying 91.6% of the ∑₁₀OPFRs), while TCPP, TCEP, and tri-o-tolyl phosphate (o-TCP) were the most common in the suspended particulate phase, accounting for 90.1% of the ∑₁₀OPFRs. Across the three sampling periods, there was no significant seasonable variation for OPFRs either in the water phase or in the suspended particulate phase, except for TCEP and TCPP in the water phase. Compared with research findings relating to concentrations of OPFRs around China and abroad, the OPFRs of the Yellow River (Henan Area) in the water phase were at a moderate level. Suspended particles (SS) had a very important impact on the transportation of OPFRs in the studied area, with about 83.9% of ∑₁₀OPFRs inflow attributed to SS inflow and about 81.7% of ∑₁₀OPFRs outflow attributed to SS outflow. The total annual inflow and outflow of OPFRs were 7.72 × 10⁴ kg and 6.62 × 10⁴ kg in the studied area, respectively.