Occurrence And Distribution Of Typical Organophosphorus Ester Flame Retardants In The Surface Water And Sediment In Taihu Lake

Organophosphorus flame retardants (OPFRs), with their increasing production and consumption, have already become one of the hot research projects in the environmental science area. According to a number of reports, some OPFRs are carcinogenic, potentially carcinogenic and supposed to be neurotoxic. As OPFRs are normally employed as additives, not chemically bonded, they can be easily released into surrounding environment. Taihu Lake, which is the second largest freshwater lake in China, is surrounded by many OPFRs manufacturing factories. However, little is known about the pollution status of OPFRs in the surface water and sediment in Taihu Lake, which is one of the important issues for safety of drinking water and aquatic ecosystems.In this thesis, the determination methods of 9 typical OPFRs in the surface water and sediment were developed, and vital baseline information on OPFRs’ distribution in surface water and sediment from Taihu Lake was provided. The main work of this paper is as follows:(1) A solid phase extraction (SPE) coupled with gas chromatography-mass spectrometry (SPE-GC-MS) method was developed for the determination of 9 typical OPFRs. The target compounds in water samples were concentrated by Poly-Sery PSD SPE cartridge, and then eluted by 4 mL of ethyl acetate. The OPFRs were qualified and quantified by GC-MS via selective ion scan monitoring method (SIM). Good linearity could be observed in the range of 2.0 to 1000 ng/L of OPFRs, with correlation coefficients varying from 0.9937 to 0.9995. The limits of detection and limits of quantification were 0.006-0.850 ng/L and 0.015-2.000 ng/L, respectively. The recoveries for spiked samples of pure water and river water ranged from 70.3% to 114.3%, with the standard deviations less than 15%, except for TEHP. The satisfied recovery of TEHP was achieved when the spiked concentration was less than 50 ng/L. The results indicated that the SPE-GC-MS analytical method established in this study was sensitive and accurate enough for determination of OPFRs in samples from surface water.(2) A accelerated solvent extraction (ASE), gel permeation chromatography (GPC), SPE coupled with GC-MS method was developed for the determination for 9 typical OPFRs in the sediment. The optimal responses were observed extracting 5g sediment with ethyl acetate at 90℃ and 1500 psi for 5 min. The obtained extract was passed through GPC, and the fraction between 7.5 and 20.0 minute was collected. Further cleanup by SPE was conducted. The relative recoveries for the studied OPFRs ranged from 87.0%-114.3%, and the absolute recoveries between 37.0% and 94.1%, with the standard deviations less than 15%. The limits of detection and limits of quantification were 0.003-0.340 ng/mg and 0.012-0.800 ng/mg, respectively.(3) Concentrations, seasonal and spatial distribution of OPFRs were investigated in the surface water of Taihu Lake, China. Total concentrations of OPFRs were found to be 375-3079 ng/L, with tri(1-chloro-2-propyl) phosphate(TCPP), tri(2-chloroethyl) phosphate (TCEP), triphenylphosphine oxide (TPPO) and triethyl phosphate (TEP) as the dominant compounds. Generally, concentrations of OPFRs in Northern and Western parts of the lake were highest, supposed to be affected by inflowing rivers receiving sewage water from industrial areas. Dilution process and good self-purification ability are assumed to be the reason for lower concentrations of OPFRs in the Southern part. Seasonal dependency of TEP, TPPO and total OPFRs are assumedly caused by biodegradation, evaporation, photodegradation and discharge. In addition, according to the study of multivariate statistics for all sampling sites of Taihu Lake, the higher concentrations of TCEP and TCPP in Northern Taihu Lake were caused by point sources, and nonpoint source and diffusion could be the main contributor of OPFRs in the Southern part.(4) Total concentrations of OPFRs in the sediments of Taihu Lake were found to be 42-680 μg/kg, with TnBP as the dominant compound. The distribution in the sediments of Taihu Lake showed no obvious spatial difference. Seasonal dependency of OPFRs in the sediments of Taihu Lake was found as April, January> July, just consistent with the occurrence in the surface water of Taihu Lake. This suggested that OPFRs could be easily degraded in the sediments.