Occurrence, distribution and ecological risk assessment of organophosphorus flame retardants and plasticizers in sediment samples along the Vaal River catchment, South Africa

Abstract

The occurrence, distribution and ecological risk assessment of twelve (12) organophosphorus flame retardants (OPFRs) were investigated in sediments from the Vaal River, South Africa. Six halogenated OPFRs [tris-(2-chloroethyl) phosphate (TCEP), three isomers of tris-(chloropropyl) phosphate (TCiPPs), tris-(1, 3-dichloro-2-propyl) phosphate (TDCiPP) and tris-(2, 3 dibromopropyl) phosphate (TDBPP)] and six non-halogenated OPFRs [tris-(n-butyl) phosphate (TBP), tris-(phenyl) phosphate (TPhP), tris-(butyl ethoxy) phosphate (TBOEP), tris-(2-ethylhexyl) phosphate (TEHP), diphenyl- 2-ethylhexyl phosphate (DPEHP) and tris-(m-cresyl) phosphate (m-TCP)] were detected in this study. The concentrations of twelve OPFRs in total (Σ12OPFRs) ranged from 68 to 278 ng g−1 dry weight (dw) with the mean and median of 138 and 120 ng g−1; respectively. The non-halogenated OPFRs showed more abundances than the halogenated OPFRs with TDBPP, TBP, and TBOEP the most abundant compounds. Generally, concentrations of OPFRs in more urbanized region were higher than those in less urbanized regions. When the concentrations of OPFRs and total organic carbon (TOC) were correlated, a moderate and significant correlation (p 1) while TBOEP, TPhP, and TBP posed medium risk (0.1 < HQ < 1) with the remainder posing negligible risk (HQ < 0.01). The data obtained in this study provides valuable information on the occurrence and risks of the investigated OPFRs within Vaal River. Keywords: OPFRs, Concentrations, Risk assessment, Sediments, Vaal river