Distribution and leaching behavior of organophosphorus and brominated flame retardants in soil in Chengdu

A total of 29 surface farmland soil samples were collected to investigate the spatial distribution and composition characteristics of 13 organophosphorus flame retardants (OPFRs), 11 polybrominated diphenyl ethers (PBDEs), and 8 novel brominated flame retardants (NBFRs) in Chengdu, China. The OPFRs were widely detected in the farmland soil with concentrations ranging from 2.92 to 160 ng g-1 dry weight (dw). BDE-209 was found with a concentration range of n.d. to 50.4 ng g-1 dw, and was the main PBDE congener accounting for 90% of ΣPBDEs in the surface farmland soil. In the case of NBFRs, only TBB and BTBPE were detected in the farmland soil from rural areas of Chengdu. There was no obvious spatial distribution of the OPFRs among different administrative regions in Chengdu (p > 0.05), but the maximum concentration of OPFRs was found in a furniture production area. Leaching experiments showed that the concentration of most of the investigated OPFRs in two kinds of soils with different mechanical compositions and TOC contents decreased with the increase of soil depth. Addition of DOM could decrease the OPFR levels in the leachate by less than 25%, with the exception of TCPP, which decreased by up to 45%. More importantly, TCEP and TCPP exhibited stronger mobility than the other OPFRs in soil, and the migration capacity of TCPP was more sensitive to the DOM level, indicating that TCEP might more easily migrate from soil to groundwater in the nature.