Multimedia distribution and exchange characteristics of organophosphorus flame retardants in a typical semi-arid city in China

After the ban on polybrominated diphenyl ethers (PBDEs), the replacement of these compounds with organophosphorus flame retardants (OPFRs) has drawn widespread attention worldwide. In arid/semi-arid regions, characteristics such as low precipitation, frequent strong winds, and low soil organic carbon content potentially influence the environmental fate of OPFRs. In this study, we investigated the concentrations of nine OPFRs in water, sediment, soil, air, and dry deposition in Lanzhou, an arid/semi-arid region in China. The total concentration of OPFRs (Sigma 9OPFRs) were 54.8-334 ng/L in water, 37.3-484 ng/g (dry weight, dw) in sediment, 134-510 ng/g (dw) in urban soil, 1.53-6.22 ng/m3 in urban air, and measured dry deposition fluxes were 119-681 ng/(m2 center dot d). TPrP, TDCPP and TCPP were the primary OPFR individuals in water and sediment, while TPrP, TDCPP and TPPO predominated in urban soil and air. The fugacity approach revealed the environmental fate of OPFRs were mainly: soil-to-air, air-to-water and sediment-to-water. Ulteriorly, intermediate exchange fluxes were calculated. This study reveals that in this climatic region, urban soil acts both as a "sink" for emissions and a "source" for re-emissions into the atmosphere, further emphasizing the significance of atmospheric transport as a critical pathway in this area.