Occurrence and Distribution of the Organophosphate Esters in Soils of Mixed-land Use Area in Chongqing City

Abstract

Organophosphate esters (OPEs) in surface soil of four different functional areas in Chongqing were identified and quantified using ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS). The composition and characteristics of OPEs were discussed along with the relationships between soil organic matter (SOM) and OPEs through correlation analysis, and possible sources of OPEs were simultaneously investigated through principal component analysis (PCA). The results showed that the concentrations of ∑OPEs ranged from 10.7 to 108 ng·g-1 dry weight, with a mean concentration of 46.4 ng·g-1, which was at the low-level end of the global figure. The average concentration was 55.6 ng·g-1 in the industrial area, 55.5 ng·g-1 in the residential area, 41.8 ng·g-1 in the commercial area, and 34.1 ng·g-1 in the city park. Tris (1-chloro-2-propyl) phosphate (TCPP) and 2-ethylhexyl diphenyl phosphate (EHDPP) were dominant compounds, contributing up to 31.5% in the industrial area for TCPP and 23.4% and 24.7% in the commercial area and city park, respectively, for EHDPP. Significant relationships between concentrations of SOM and ∑OPEs (P<0.05) and tricresyl phosphate (TCP) (P<0.01), respectively, indicated that SOM was a factor affecting the concentration and distribution of the OPEs. The PCA suggested that there were multiple sources of OPEs in urban soil. Sewage irrigation, road runoff, indoor source pollution, and sludge reuse could be potential sources of soil OPEs.