Papers by Keyword: PBDEs

Abstract: Juvenile sole (Cymoglossus robustus) were exposed to BDE-47 and BDE-99 through feeding in the laboratory for 60 days, followed by 60 days of clean food, to examine bioaccumulation and potential thyroid hormone disruption effect. The results show that both BDE-47 and BDE-99 accumulate in fish tissues. The free tri-iodothyronine (T3) concentrations in the plasma of sole varied significantly throughout the experiment but were not related to PBDEs exposure. In contrast, plasma levels of thyroxine levels (T4) were lower in both groups of PBDE-exposed fish compared with control fish after 60 days of exposure, suggesting that PBDEs may influence thyroid homeostasis.

Abstract: The quantitative structure property relationship (QSPR) study was performed in this work to develop models to predict the normalized reaction rate constants for the reductive debromination of polybrominated diphenyl ethers (PBDEs) by zero-valent iron (ZVI). In order to consider the solvent effect, conductor-like polarizable continuum model (CPCM) was applied to optimize the geometries and obtain the molecular descriptors using the pseudopotential basis set. The prediction results with the inclusion of solvent effect are slightly better than that of the corresponding gas-phase calculations. The artificial neural network (ANN) model could be more satisfactory to predict the rate constants than the partial least squares regression (PLSR) and principal component analysis-multiple linear regression analysis (PCA-MLR) models.

Abstract: Neutral PBDEs congeners and their corresponding radical anions were studied with the pseudopotential method of stuttgart group (SDD) effective-core potentials basis set for the bromine atoms and the all-electron basis set for all other atoms. The pseudopotential method can be used for compounds containing heavy elements with relativistic effects and can reduce the computational time. The quantitative structure property relationship (QSPR) study was also performed in this work to develop models to predict the normolized reaction rate constants for the reductive debromination of polybrominated diphenyl ethers (PBDEs) by zero-valent iron (ZVI). The partial least squares regression (PLSR), principal component analysis-multiple linear regression analysis (PCA-MLR), and back propagation artificial neural network (BP-ANN) approaches were employed for the QSPR study between the molecular descriptors and the logarithm of normalized reaction rate constants of fourteen selected BDE congeners. The results show that the ANN models could be more satisfactorily to predict the rate constants than the PLSR and PCA-MLR models.

Abstract: To investigate the transfer of PBDEs from products into the aqueous media, experiments and analysis were carried out by contacting TV housing plastics with distilled and dissolved humic solution (DHS) in brown bottles in the artificial climate box. The leaching test conditions were a liquid-to solid ratio of 100:1, and a contact period of 1, 2, 4, 7, 10, 13, 16 and 20 day (s), with pH of 3, 5, 7, 9 and temperature of 15, 20, 25 °C. The leaching concentrations of PBDE increased with DHS rather than distilled water, and were found to be remarkably enhanced when TOC of DHS increased. Despite no detection of most of the lower BDEs in distilled water, most homologues could be detected in DHS, and their solubility increased according to the contact time; those of highly BDEs increased to 10 times their maximum solubility in distilled water. Temperature had limited influence for the limited range investigated. Lower pH generally resulted in higher transfer of PBDEs to aqueous phase.

Abstract: In this study, sewage sludge samples were collected from 25 wastewater treatment plants (WWTPs) in Shanghai, and free and bound PBDEs were extracted in different ways. The concentrations of free and bound PBDEs were in the range of 111.69 to 13119.59 ng/g dry weight (dw) and 4.30 to 60.17 ng/g dw, respectively. BDE209 were the dominate congener and the concentrations of free and bound BDE209 ranged from 89.64 to 12424.84 ng/g dw and 0.85 to 44.00 ng/g dw, respectively. The concentrations of bound PBDEs were quite stable, indicating bound PBDEs werent high related with the input of total PBDEs. The fractions of bound PBDE congeners increased with the numbers of Br atoms, which suggested that PBDE congeners with low molecular weights were more prone to desorb from micro-pores of organic matters in sewage sludge. The fractions of bound PBDEs in total PBDEs were in the range of 0.16 to 22.73%, suggesting bound PBDEs played an important role in farmland soils after sludge application.

Abstract: In the current study, two of the most environmentally relevant Polybrominated diphenyl ethers (PBDEs) were individually evaluated for toxic effects on rotifer Brachionus plicatilis. The results showed that the life span declined significantly in all treatment groups (0.05mg/L, 0.1mg/L, 0.2mg/L BDE-47 and BDE-209) compared to the control, and BDE-47 caused significant decrease compared to BDE-209 at 0.2mg/L treatment group. Significant increases of intracellular levels of reactive oxygen species (ROS) occurred in all treatment groups except for 0.05mg/L BDE-209 treatment group compared to the control, and significant increases were observed in all BDE-47 treatment groups compared to the equivalent treatment groups of BDE-209. Meanwhile significant increases of intracellular calcium levels ([Ca²⁺]_in) occurred in 0.1mg/L, 0.2mg/L BDE-47 and 0.2mg/L BDE-209 treatment groups compared to the control, and BDE-47 cause significant increase compared to BDE-209 at 0.2mg/L treatment group. The present study demonstrated that life span, ROS and Ca²⁺ were involved in PBDEs toxic effects, and toxicities of BDE-47 were higher than BDE-209. Otherwise, the toxic effects in both BDE-47 and BDE-209 were similar, which suggest that the toxic effects of two PBDEs congeners may be caused by the same toxic mechanism of action.

Abstract: An electrokinetic and magnetic remediation system of polybrominated diphenyl ethers (PBDEs) contaminated soil was built in the laboratory. The characteristics of BDE15 migration under non-uniform electric field and uniform magnetic field were investigated. The results indicated that current and temperature in the soil reached the maximum values 100mA and 14°C respectively in 6h; the moisture content of soil near the cathode and anode was higher than in the middle position; pH values of soil increased gradually from the anode to the cathode and acid-base interface was in the soil area between 3cm from anode and 5 cm from anode; BDE15 mainly enriched in the area 5cm from the anode and reached 22.69μg·g^-1.

Abstract: The compositional profiles and health risks of polybrominated diphenyl ethers (PBDEs) were analyzed with urban surface dust and soil samples from industrial, traffic and green areas in Shanghai. The total concentration of ∑8PBDE in urban surface dust ranged from 1.90 to 162 ng/g with a mean value of 29.6 ng/g, while the total concentration of ∑8PBDE in urban surface soil ranged from 1.09 to 39.9 ng/g with a mean value of 9.46 ng/g. ∑PBDEs have a higher concentration in urban dust samples as compared to urban soil samples. Cancer risks were calculated by Average Daily Dose (ADD) for human exposure to urban surface dust and soil containing PBDEs. Concentrations in Shanghai were 3.66×10-4 and 5.85×10-5 for children, and 1.58×10-4 and 6.44×10-5 for adults. Meanwhile, the health risk assessment has indicated that the intake of PBDEs via ingestion and dermal contact were higher than that via inhalation.

Abstract: Quantitative structure-property relationship (QSPR) models were developed in the present work for photodegradation rate constants (kp) of fifteen individual polybrominated diphenyl ethers (PBDEs) in methanol/water (8:2) by UV light in the sunlight region. The molecular descriptors used in the QSPR models were calculated by the two semi-empirical quantum mechanical methods, RM1 and PM6, respectively. Both multiple linear regression (MLR) and artificialneural network (ANN) were applied in this study. The statistic qualities of the MLR models based on the molecular parameters obtained by RM1 and PM6 calculations were both good with the R values of 0.987 and 0.990, respectively. The QSPR model built by the ANN method with the molecular parameters calculated with PM6 is slightly better than that with RM1.

Abstract: Electrokinetics is a soil remediation technology under development. One of its advantages is that it can realize in suit remediation. A series of bench-scale experiments were carried out and result showed that electrokinetic technology was effective in promoting BDE15 desorption and migration in soil, and its effect depends on the type of electrodynamics. Ion concentration was changed for the electrolysis reaction, and lead to current changed. The current variation tendency was increase first then decrease.Soil pH and temperature was changed as a result of electric field, soil resistance and temperature increases, the cathode temperature up to 40°C.