Shutao Gao

Hexabromocyclododecanes in surface soils from E-waste recycling areas and industrial areas in South China: concentrations, diastereoisomer- and enantiomer-specific profiles, and inventory.

Hexabromocyclododecanes (HBCDs) are raising concern because of their potential persistence, bioaccumulation, and toxicity. In this study, we investigated the concentrations, diastereoisomer- and enantiomer-specific profiles, and mass inventories of HBCDs in 90 surface soils from two e-waste recycling areas (Qingyuan, Guiyu) and from industrial areas in South China. The mean concentrations of total HBCDs in the surface soils ranged from 0.22 to 0.79 and from 0.31 to 9.99 ng/g dw for two surrounding e-waste recycling sites and industrial areas, respectively. The highest total HBCD concentration (284 ng/g dw) was found at the e-waste recycling site in Qingyuan, while total HBCD levels fell dramatically with increasing distance from the recycling site, suggesting that the e-waste recycling activities were an important source of HBCDs. The diastereoisomer profiles in 75 of the 90 soil samples differed from those of the commercial products. The mean enantiomeric fraction values for α-, β-, and γ-HBCDs in soils ranged from 0.503(0.010) to 0.507(0.003), 0.494(0.003) to 0.506(0.009), and 0.502(0.003) to 0.511(0.006), respectively, suggesting that there was no stereoselective transformation of the three diastereoisomers. The mass inventories of HBCDs gave preliminarily estimates of 3.42 kg and 1.84 tonnes for the e-waste recycling areas and industrial areas, respectively. It is notable that the diasteroisomer and enantiomer profiles of this study failed to distinguish definitely that the isomeric transformation occurred during the product processing or in the environmental matrix. Further laboratory studies on abiotic and biotic transformation are needed to clarify this issue.

Levels and isomer profiles of Dechlorane Plus in the surface soils from e-waste recycling areas and industrial areas in South China

Dechlorane Plus (DP) is a highly chlorinated flame retardant. Levels of DP were measured in surface soils from e-waste recycling areas and industrial areas in South China. Higher DP levels were found in e-waste recycling areas (undetectable-47.4 ng/g) than those in industrial areas (0.0336-4.65 ng/g) in South China. The highest DP concentration (3327 ng/g) was found at the e-waste recycling site in Qingyuan, while DP levels fell dramatically with increasing distance away from the recycling site, suggesting that the e-waste recycling activities are an important source of DP emissions. The mean ratios of anti-DP to total DP (fanti) for different sampling areas ranged from 0.58 to 0.76 and showed no significant difference from the ratio for the technical DP products (t-test, p>0.05). Further intensive studies are needed to investigate the process of DP degradation and its degradation products.

Polybrominated diphenyl ethers in surface soils from e-waste recycling areas and industrial areas in South China: Concentration levels, congener profile, and inventory

Polybrominated diphenyl ethers (PBDEs) were determined in 60 surface soils from two e-waste recycling sites (Qingyuan and Guiyu, China) and their surrounding areas to assess the extent and influence of PBDEs from e-waste recycling sites on the surrounding areas. A total of 32 surface soils from industrial areas in South China were also investigated for comparison. The mean concentrations of total PBDEs in the e-waste recycling sites of Guiyu and Qingyuan were 2,909 and 3,230 ng/g dry weight, respectively, whereas the PBDE concentrations decreased dramatically (1-2 orders of magnitude) with increasing distance from the recycling site, suggesting that the e-waste recycling activities were the major source of PBDEs in the surrounding areas. Decabromodiphenyl ethers accounted for 77.0 to 85.8% of total PBDEs in e-waste recycling areas, whereas it accounted for 90.2% in industrial areas. Principal component analysis showed that the major source of PBDEs in e-waste recycling areas were a combination of penta-, octa-, and deca-BDE commercial formulations, whereas deca-BDE commercial formulations were the major source of PBDE congeners in industrial areas. The inventories of PBDEs gave preliminary estimates of 6.22 tons and 13.4 tons for the e-waste recycling areas and industrial areas. The results suggested that significantly higher PBDEs in the e-waste recycling sites have already affected surrounding areas negatively within a relatively large distance. Because of the environmental persistence, bioaccumulation, and toxicity of PBDEs, improving the recycling techniques employed at such facilities and developing e-waste management policies are necessary.

Levels and distribution of synthetic musks and polycyclic aromatic hydrocarbons in sludge collected from Guangdong Province

The levels and distribution of six polycyclic musks, three nitromusks and 15 polycyclic aromatic hydrocarbons (PAHs) were investigated in sludge collected from 19 municipal wastewater treatment plants (WWTPs) in six cities in Guangdong Province, China. PAHs were detected in all of the sludge samples, and the levels of the total 15 PAHs ranged from 177.2–4421.8 μg/kg dry weight (dw). Four polycyclic musks, 4-acetyl-1,1-dimethyl-6-tert-butylindan (ADBI), 6-acetyl-1,1,2,3,3,5-hexamethylindan (AHMI), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta (g) -2-benzopyran (HHCB) and 7-acetyl -1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydro naphthalene (AHTN), were found in these samples. The total concentrations of polycyclic musks varied from 794.4–12960.3 μg/kg dw, with HHCB and AHTN being the main components. Of the three nitromusks, 2,6-dinitro-3-methoxy-4-tert- butyl - toluene (MA) was only found in one sludge sample at the limit of detection (LOD) level, while 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (Musk xylene, MX) and 4-acetyl-1-tert-butyl-3,5-dimethyl-2,6-dinitrobenzene (Musk ketone, MK) were found at levels ranging from the LOD to 65.8 μg/kg dw and LOD to 172.7 μg/kg dw, respectively, in most of the sludge samples. The PAHs, polycyclic musks and nitro musks were also shown to have various distribution patterns, possibly due to their different wastewater sources and wastewater treatment technology.

Hexabromocyclododecanes in the indoor environment of two cities in South China: their occurrence and implications of human inhalation exposure

Indoor and outdoor air samples were collected from two industrialized cities (Guangzhou and Foshan) in Southern China to determine the concentrations and diastereoisomer profiles of hexabromocyclododecanes (HBCDs) in built environments. The mean concentrations of total HBCDs in air were 5.43 pg m−3 in homes, 8.21 pg m−3 in offices, 48.2 pg m−3 in other workplaces and 33.3 pg m−3 in the air outdoors. These HBCD levels are slightly higher than or comparable with those at the remote or urban sites in the United States, but are significantly lower than those in the European atmosphere. Diastereoisomer profiles of the samples indicated that α-HBCD was the dominant isomer, with a relative abundance ranging from 53.2% to 83.0%, which is notably different from its fractions in the air samples from the UK and the domestic technical-grade mixtures. Analysis of the gas-particle distribution showed that HBCDs were present predominantly (87.6–99.9%) in the particle phase. The estimated average daily human exposure to HBCDs via inhalation was 0.39 ng day−1 for adults, which is one order of magnitude lower than the values (5.0 and 5.47 ng day−1) for the UK adults reported in two other studies. Further air and dust sampling and continued monitoring are needed to improve our understanding of human exposure to HBCDs.

Determination of polybrominated diphenyl ethers in soils and sediment of Hanfeng Lake, Three Gorges.

As ubiquitous organic contaminants, polybrominated diphenyl ethers (PBDEs) were evaluated to explore the impacts of the water level fluctuating zone (WLFZ) on organic pollutant behavior and the retention mechanism of organic pollutants in the bank–WLFZ–water system of Hanfeng Lake in the Three Gorges region of China. The mean concentrations of total PBDEs were 103, 75.2, and 568 ng g−1 dry wt for bank soils, WLFZ soils, and sediment samples, respectively. Except for sampling sites S1 and S2, the levels of PBDEs decreased in the order of sediment>WLFZ soil > bank soil, suggesting that PBDEs were transferred from bank soil to WLFZ soil and finally deposited in the sediment. Decabromodiphenyl ethers (deca-BDEs) were the predominant congener in the study area, comprising 93.8% to 98.3% of the total PBDEs. Greater photolytic degradation of deca-BDEs was suggested in bank soils based on a higher relative abundance of octa- and nona-BDEs than in WLFZ soils and sediment. This may have occurred because deca-BDEs in bank soils have relatively longer sunlight exposure than in WLFZ soils and sediment due to the annual alternation of water storage and drainage in the catchments of the Three Gorges Reservoir. More in-depth investigations of contaminants in bank–WLFZ–water systems are needed due to the large areas of WLFZ created by the construction of the Three Gorges Dam and their importance to the balance of aquatic ecosystems.

Determination of ten hexabromocyclododecane diastereoisomers using two coupled reversed-phase columns and liquid chromatography/ tandem mass spectrometry

RATIONALE Hexabromocyclododecanes (HBCDs) are raising concern due to their potential persistence, bioaccumulation and toxicity. Apart from the widely reported isomers α-, β-, γ-HBCD, other HBCD diastereoisomers such as δ-HBCD have been also recently found in environmental media and biota. These newly reported diastereoisomers might give more insight into the degradation and biotransformation of HBCDs. METHODS A reversed-phase C18 column coupled to a C8 column was used to improve the chromatographic resolution. A gradient mobile phase consisting of methanol, acetonitrile, and water, as well as tandem mass spectrometry parameters, were optimized. Ten HBCD diastereoisomers were finally determined by liquid chromatography/tandem mass spectrometry in multiple reaction monitoring mode with negative electrospray ionization. RESULTS Eight of the ten HBCDs could be chromatographically separated by using the coupled reversed-phase columns. Results of the method validation indicate high reproducibility and good sensitivity. The limit of detection ranged from 0.4 to 0.8 pg, and the relative standard deviations of intra- and inter-day injections ranged from 1.8 to 5.1% and from 2.7 to 9.5%, respectively. The developed method was further applied to the analysis of HBCDs in HBCD commercial products and soil samples. δ-, η-, θ-, and ε-HBCD were detected in commercial products and soil samples. CONCLUSIONS The present study revealed that δ-, η-, θ-, and ε-HBCD might occur ubiquitously in environmental media and biota. These newly reported diastereoisomers may help us to better understand the fate and transformation of HBCDs in the environment.

Compound‐specific stable carbon isotope analysis of galaxolide enantiomers in sediment using gas chromatography/isotope ratio monitoring mass spectrometry

RATIONALE Both chiral analysis and compound-specific stable carbon isotope analysis have limitations when applied to environmental research. However, the combination of these two techniques might overcome their respective limitation and give more insight into the enantioselective fate and source apportionment of chiral organic contaminants. METHODS After Soxhlet extraction and clean-up, sediment extracts were further pre-concentrated using normal-phase preparative high-performance liquid chromatography to isolate sufficient quantities of highly purified galaxolide (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran; HHCB). The enantiomeric fractions and stable carbon isotopes of the HHCB were determined using gas chromatography/mass spectrometry (GC/MS) and GC/isotope ratio mass spectrometry (IRMS). RESULTS The method was validated by analysis of the enantiomeric fractions and the stable carbon isotope ratios of the HHCB standard at each step of the pre-concentration procedure, and no significant enantiomeric and isotopic fractionation was found. The sediment sample was further used to test the developed method, and it was shown that the HHCB enantiomers in the sediment sample exhibited significantly different δ(13) C values (-33.03 to -24.57‰) and a slight enantiomeric fractionation (0.507 and 0.490) from a HHCB standard reference compound (-26.50 to -26.21‰ for δ(13) C values, and 0.519 and 0.497 for enantiomeric fractions). CONCLUSIONS This work offers a novel approach to elucidating the sources and the abiotic or biological transformation processes of HHCB in the environment and will offer a perspective for assessing the environment fate of any chiral organic compound.

A simple analytical method for the simultaneous determination of multiple organic pollutants in sediment samples

Graphical abstract

Occurrence, distribution and ecological risks of organophosphate esters and synthetic musks in sediments from the Hun River

The Hun River is an important main tributary of the Liao River system. It is located in northeast China, and provides water resources for agriculture and industry. A man made reservoir (Dahuofang Reservoir, DHF) has been constructed mid-stream in the Hun River, supplying drinking water to surrounding cities. Pollution from organic contaminants is of great concern. In the present study, 40 sediment samples were collected and analyzed for the occurrence and distribution of two groups of emerging organic pollutants; namely, organophosphate esters (OPs) and synthetic musks (SMs). In all samples taken from upstream of the Hun River (UHR), downstream of the Hun River (DHR), and from DHF, the following concentrations were recorded: 0.141-4.39, 1.21-245, and 0.117-0.726 µg/kg galaxolide (HHCB), and 0.098-3.82, 2.79-213, 0.430-0.956 µg/kg tonalide (AHTN), respectively. For OPs, seven target analytes were detected in most of the sediment samples, with chlorinated OPs Tris-(2-chloroethyl) phosphate and Tris(2-chloro-isopropyl) phosphate being the dominant components, at levels varied in the range of LOD-0.810, ND-49.6, and 0.532-3.18 µg/kg, and LOD-0.786, ND-60.1, and 0.352-1.32 µg/kg from UHR, DHR and DHF, respectively. The elevated levels of these target compounds were detected in DHR, including its two main tributaries, Xi River and Pu River, which drain through cities with industrial development and dense populations. Our results indicate that domestic and industrial wastewater contributed to OPs and SMs sediment pollution, posing low to medium ecological risks to sediment dwelling organisms.