Yue Ren

Occurrence and characteristics of polybrominated dibenzo-p-dioxins and dibenzofurans in stack gas emissions from industrial thermal processes.

The occurrence and characteristics of 2,3,7,8-substituted polybrominated and polychlorinated dibenzo-p-dioxins and dibenzofurans (PBDD/F and PCDD/F) from various combustion and metallurgic industrial thermal processes were investigated. PBDD/F levels from metallurgic processes (TEQ) concentrations from 0.14 to 1.5 ng Nm(-3), mass concentrations from 0.56 to 5.8 ng Nm(-3)) were markedly higher than those from combustion processes (TEQ) concentrations from 0.010 to 0.054 ng Nm(-3), mass concentrations from 0.025 to 0.15 ng Nm(-3)). This indicated that metallurgic processes could be important sources of PBDD/F. Consequently, more attention should be paid to the metallurgical emission sources in addition to combustion of brominated flame retardants (BFRs) and related products. Specific isomeric patterns for PCDD/F from various industrial sources were highly consistent, while PBDD/F patterns were not. This revealed that PCDD/F might form through a common mechanism such as de novo synthesis mechanism, while PBDD/F might form by different mechanisms in thermal processes such as precursor mechanisms. Finally, an approach to identify the PBDD/F sources in ambient air by using the PBDD/F to PCDD/F ratio was developed.

Levels, profiles and source identification of PCDD/Fs in farmland soils of Guiyu, China.

The present study finished the first comprehensive survey of polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) in farmland soils of Guiyu, China. Guiyu was a major electronic wastes (EWs) dismantling area, but primitive and crude EWs disposal manner had led to severe PCDD/Fs pollution there. Twenty-three farmland soil samples covering the entire Guiyu region were analyzed. Toxic equivalent quantities (I-TEQs) of soils in EWs disposal areas were 5.7-57pg TEQ g(-1), and the total concentrations of tetra- to octa-homologues were 2816-17738pgg(-1). The SL district was a heavily contaminated area, and the neighboring SMP town was influenced by Guiyu. EWs disposal might be the source of PCDD/Fs. The homologue profiles were of three types, representing different disposal manner of EWs. Tetrachlorodibenzo-p-dioxins (TCDDs) and octachlorodibenzo-p-dioxin (OCDD) could be used as indicators for source identification, open thermal disposal of EWs was inclined to lead to formation of TCDDs, OCDD was a product of non-thermal processes.

Occurrence and impact of polychlorinated dibenzo-p-dioxins/dibenzofurans in the air and soil around a municipal solid waste incinerator

To assess the influence of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) on the environment in the vicinity of municipal solid waste incinerators (MSWIs), we determined the levels of PCDD/Fs in air and soil samples collected around a MSWI, which is the largest in China. The International Toxicity Equivalency Quantity (I-TEQ) concentrations of PCDD/Fs in air samples were from 0.0300 to 1.03pgI-TEQ/m(3) (0.445-13.6pg/m(3)), with an average of 0.237pgI-TEQ/m(3), while in soil samples they ranged from 0.520 to 3.40pgI-TEQ/g (2.41-88.7pg/g) with an average of 1.49pgI-TEQ/g. The concentrations of PCDD/Fs in air and soil samples were comparable to other areas, and PeCDFs were the dominant contributors, which was different from stack gas homologue patterns. Multivariate statistical analysis showed that PCDD/Fs emission from the MSWI did not directly affect the profiles of PCDD/Fs in air and soils, so that vehicles and unidentified emission sources should be considered. The daily inhalation levels of PCDD/Fs for children (0.0110 to 0.392pgI-TEQ/(kg·day) and adults (0.00600 to 0.221pgI-TEQ/(kg·day) near the MSWI were lower than the tolerable daily intake of 1.00 to 4.00pg WHO-TEQ/(kg·day), but in winter the values were higher than in summer. These results can be used as basic data for assessing the risk of PCDD/Fs exposure in residents living around this MSWI, and more monitoring programs and studies should be carried out around MSWIs.

Polycyclic aromatic hydrocarbon concentrations, compositions, sources, and associated carcinogenic risks to humans in farmland soils and riverine sediments from Guiyu, China.

The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were measured in 23 farmland soil samples and 10 riverine sediment samples from Guiyu, China, and the carcinogenic risks associated with PAHs in the samples were evaluated. Guiyu is the largest electronic waste (EW) dismantling area globally, and has been well known for the primitive and crude manner in which EWs are disposed, such as by open burning and roasting. The total PAH concentrations were 56-567 ng/g in the soils and 181-3034 ng/g in the sediments. The Shanglian and Huamei districts were found to be more contaminated with PAHs than the north of Guiyu. The soils were relatively weakly contaminated but the sediments were more contaminated, and sediments in some river sections might cause carcinogenic risks to the groundwater system. The PAHs in the soils were derived from combustion sources, but the PAHs in the sediments were derived from both combustion and petroleum sources.

Simple and rapid determination of PCDD/Fs in flue gases from various waste incinerators in China using DR-EcoScreen cells.

In developing countries such as China, there is a strong need for simple and rapid bioassays for the determination of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in environmental samples; i.e., flue gas and fly ash from waste incinerators. In this study, we applied the DR-EcoScreen cell (DR-cell) assay to determination of PCDD/Fs in 78 flue gas samples obtained from various waste incinerators in China between 2009 and 2011. The flue gas samples were obtained from four kinds of incinerators, classified into hazardous, medical and municipal-solid waste, and iron ore sintering, and the flue gas extracts were cleaned up using an SPD-600 automated-sample preparation device for DR-cell assay. The PCDD/Fs values obtained from the DR-cell assay were compared with those obtained from conventional high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS) analysis. The bioanalytical equivalent (BEQ) values obtained from the DR-cell assay were very closely correlated with the international toxicity equivalent (I-TEQ) values from HRGC-HRMS analysis (r2=0.98, n=78), while the BEQ values were 5.52-fold higher than the I-TEQ values, as the PCDFs, which account for 80% of the total I-TEQ value, were overestimated by DR cell-assay. Therefore, we multiplied the BEQ values from the DR-cell assay by a conversion coefficient (0.181, the reciprocal of 5.52), and could approximate the TEQ values from the HRGC-HRMS analysis. These results suggest that the DR-cell assay combined with SPD-600 cleanup provides a promising method for the simple and rapid screening of PCDD/Fs levels in flue gas samples, such as those from various waste incinerators in China.

Simultaneous determination of three alternative flame retardants (dechlorane plus, 1,2-bis(2,4,6-tribromophenoxy) ethane, and decabromodiphenyl ethane) in soils by gas chromatography-high resolution mass spectrometry.

A gas chromatography-high resolution mass spectrometry (GC-HRMS) method has been developed for the simultaneous determination of three alternative flame retardants, dechlorane plus (DP), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and decabromodiphenyl ethane (DBDPE) in soils. The soil samples were extracted by accelerated solvent extraction, followed by purification with concentrated sulfuric acid partitioning combined with acid-base silica gel column separation. The gas chromatography featured with a thermostable capillary column of short length and a thin stationary phase was operated in pulse injection mode. A double-focusing magnetic sector high resolution mass spectrometer with electron impact ionization was used for quantification of the analytes. The method detection limits were 0.27-0.33 pg for DPs, 0.41 pg for BTBPE, and 36 pg for DBDPE. The mean recoveries for DPs, BTBPE, and DBDPE in spiked soils were 88-107%, 78-97%, and 74-113%, respectively, with relative standard deviations ranging from 5.2% to 18%. The recoveries of (13)C-labeled standards for DPs, BTBPE, and DBDPE in soil samples were 45-110%, 67-118%, and 27-82%, respectively. These results met the acceptable range of labeled standards for analysis of polybrominated diphenyl ethers as specified by the USEPA 1614 method.