Polybromobenzene pollutants in the atmosphere of North China: levels, distribution, and sources

Confounding effects of seasonality and anthropogenic river regulation on suspended particulate matter-driven mercury transport to coastal seas

Riverine mercury (Hg) is mainly transported to coastal areas in suspended particulate matter (SPM)-bound form, posing a potential threat to human health. Water discharge and SPM characteristics in rivers vary naturally with seasonality and can also be arbitrarily disrupted by anthropogenic regulation events, but their effects on Hg transport remain unresolved. Aiming to understand the confounding effects of seasonality and anthropogenic river regulation on Hg and SPM transport, this study selected the highly sediment-laden Yellow River as a representative conduit. Significant variations in SPM concentrations (108 - 7097 mg/L) resulted in fluctuations in total mercury (THg, 3.79 - 111 ng/L) in river water corresponding to seasonality and anthropogenic water/sediment regulation. Principal component analysis and structural equation model revealed that SPM was the essential factor controlling THg and particulate Hg (PHg) in river water. While SPM exhibited equilibrium state in the dry season, a net resuspension during the anthropogenic regulation and net deposition in the wet season demonstrated the impact of SPM dynamics on Hg distribution and transport to coastal regions. Combining water discharge, SPM, and Hg concentrations, a modified model was developed to quantify Hg flux (2256 kg), over 98% of which was in particulate phase.

A review of polybrominated diphenyl ethers and novel brominated flame retardants in Chinese aquatic environment: Source, occurrence, distribution, and ecological risk assessment

Due to the widespread commercial production and use of brominated flame retardants (BFRs) in China, their potential impact on human health development should not be underestimated. This review searched the literature on Polybrominated diphenyl ethers and Novel brominated flame retardant (PBDEs and NBFRs) (broad BFRs) in the aquatic environment (including surface water and sediment) in China over the last decade. It was found that PBDEs and NBFRs entered the aquatic environment through four main pathways, atmospheric deposition, surface runoff, sewage effluent and microplastic decomposition. The distribution of PBDEs and NBFRs in the aquatic environment was highly correlated with the local economic structure and population density. In addition, a preliminary risk assessment of existing PBDEs and PBDEs in sediments showed that areas with high-risk quotient values were always located in coastal areas with e-waste dismantling sites, which was mainly attributed to the historical legacy of electronic waste. This research provides help for the human health development and regional risk planning management posed by PBDEs and NBFRs.

Occurrence, spatial distribution, and risk assessment of brominated flame retardants in farmland soils of typical provinces in China

In the present study, we investigated the occurrence, distribution, and potential risks of 4 brominated flame retardants in farmland soils across 18 provinces of China. The total mean concentrations of the BFRs were in order as DBDPE > BDE209 > HBB > TBB. DBDPE concentration was highest at 177.208 ng/kg, revealing its long-term use and persistence across the study areas. In parts of China, DBDPE was highest in the south (Sichuan, Shaanxi and Guangdong provinces), BDE209 was highest in the south (Sichuan province) and north (Jilin province), while HBB was highest in the south (Sichuan province) and east (Anhui and Zhejiang provinces) of China. Comparisons of the results in this study to other reported studies in different regions indicated that the studied BFRs concentrations were higher in the studied provinces of China. Pearson correlation between BFRs revealed both positive and negative associations within the BFRs groups and between BFRs and soil properties (SOM, CEC, pH, EC and PS%). The mean hazard quotients (HQ) of ecological risks ranged from 8.76 × 10^-6 to 1.16 × 10^-2 (HQ < 1) while non-carcinogenic human health risk evaluation for adults ranged from 7.05 × 10^-7 - 7.48 × 10^-4 (HQ < 1) and for children 2.99 × 10^-4 - 4.30 × 10^-2 (HQ < 1). Although the risk evaluations of BFRs from farmland soils in this study were low, the results serve as useful indicators of potential cumulative and long-term threats of BFR to rural areas where there is a high conversion of agricultural lands to non-agricultural use.

Decabromodiphenyl Ether versus Decabromodiphenyl Ethane: Source, Fate, and Influencing Factors in a Coastal Sea Nearing Source Region

Both decabromodiphenyl ether (BDE 209) and decabromodiphenyl ethane (DBDPE) are still produced in large quantities in China, especially in the Shandong Province closed to the Bohai Sea (BS). This study conducted a comprehensive investigation of the distribution and budget of brominated flame retardants (BFRs) in the BS. BDE 209 was the predominant BFR in most of the investigated rivers flowing into the BS, although DBDPE exceeded BDE 209 in certain rivers as a result of the replacement of BDE 209 with DBDPE in North China. The spatial distributions of BFRs in the rivers were controlled by the proximity of the BFR manufacturing base and the extent of urbanization. BFRs' spatial distribution in the BS was influenced by a combination of land-based pollution sources, environmental parameters (e.g., suspended particulate matter, particulate organic carbon, and particulate black carbon), and hydrodynamic conditions. The spatial variation trend of BDE 209/DBDPE ratios in various environmental media provided useful information. Vertically, the BDE 209/DBDPE ratio decreased from the seawater surface layer to the sediment, indicating their differential transport in the BS. A multi-box mass balance model and analysis of BDE 209 showed that degradation was the primary sink of BFRs in seawater (∼68%) and surface sediment (∼72%) in the BS.

Organic Iodine Compounds in Fine Particulate Matter from a Continental Urban Region: Insights into Secondary Formation in the Atmosphere

Atmospheric iodine chemistry can significantly affect the atmospheric oxidation capacity in certain regions. In such processes, particle-phase organic iodine compounds (OICs) are key reservoir species in their loss processes. However, their presence and formation mechanism remain unclear, especially in continental regions. Using gas chromatography and time-of-flight mass spectrometry coupled with both electron capture negative ionization and electron impact sources, this study systematically identified unknown OICs in 2-year samples of ambient fine particulate matter (PM_2.5) collected in Beijing, an inland city. We determined the molecular structure of 37 unknown OICs, among which six species were confirmed by reference standards. The higher concentrations for ∑₃₇OICs (median: 280 pg m^-3; range: 49.0-770 pg m^-3) measured in the heating season indicate intensive coal combustion sources of atmospheric iodine. 1-Iodo-2-naphthol and 4-iodoresorcinol are the most abundant species mainly from primary combustion emission and secondary formation, respectively. The detection of 2- and 4-iodoresorcinols, but not of iodine-substituted catechol/hydroquinone or 5-iodoresorcinol, suggests that they are formed via the electrophilic substitution of resorcinol by hypoiodous acid, a product of the reaction of iodine with ozone. This study reports isomeric information on OICs in continental urban PM_2.5 and provides valuable evidence on the formation mechanism of OICs in ambient particles.

Source, fate and budget of Dechlorane Plus (DP) in a typical semi-closed sea, China

Dechlorane Plus (DP), which has severe effects on marine ecosystems, has been proposed for listing under the Stockholm Convention as a persistent organic pollutant (POPs). This study was the first comprehensive investigation of the concentration and fate of DP in the Bohai Sea (BS) based on determination of river estuary water, river estuary sediment, surface seawater, bottom seawater, and sea sediments samples. The highest water DP levels were found in river estuary in Tianjin in North China due to the huge usage of DP in recent years, and spatial distribution analysis indicates it was mainly affected by regional high urbanization and emission of E-waste. The spatial distribution of DP in the BS was mainly affected by a combination of coastal hydrodynamics and land anthropogenic activities. On the basis of multi-box mass balance, simulations of DP in seawater showed an increase from 2014 to 2025, before leveling off at 184 pg L ^-1 by a constant DP input to the BS. Riverine discharge almost contributed to the total input (∼99%) and dominated the DP levels in the BS. Degradation of DP accounted for 55.3% and 78.1% of total DP output in seawater and sediment, respectively, indicating that degradation mainly affected decline of DP in the environment.

Passive air sampling for semi-volatile organic chemicals

During passive air sampling, the amount of a chemical taken up in a sorbent from the air without the help of a pump is quantified and converted into an air concentration. In an equilibrium sampler, this conversion requires a thermodynamic parameter, the equilibrium sorption coefficient between gas-phase and sorbent. In a kinetic sampler, a time-averaged air concentration is obtained using a sampling rate, which is a kinetic parameter. Design requirements for kinetic and equilibrium sampling conflict with each other. The volatility of semi-volatile organic compounds (SVOCs) varies over five orders of magnitude, which implies that passive air samplers are inevitably kinetic samplers for less volatile SVOCs and equilibrium samplers for more volatile SVOCs. Therefore, most currently used passive sampler designs for SVOCs are a compromise that requires the consideration of both a thermodynamic and a kinetic parameter. Their quantitative interpretation depends on assumptions that are rarely fulfilled, and on input parameters, that are often only known with high uncertainty. Kinetic passive air sampling for SVOCs is also challenging because their typically very low atmospheric concentrations necessitate relatively high sampling rates that can only be achieved without the use of diffusive barriers. This in turn renders sampling rates dependent on wind conditions and therefore highly variable. Despite the overall high uncertainty arising from these challenges, passive air samplers for SVOCs have valuable roles to play in recording (i) spatial concentration variability at scales ranging from a few centimeters to tens of thousands of kilometers, (ii) long-term trends, (iii) air contamination in remote and inaccessible locations and (iv) indoor inhalation exposure. Going forward, thermal desorption of sorbents may lower the detection limits for some SVOCs to an extent that the use of diffusive barriers in the kinetic sampling of SVOCs becomes feasible, which is a prerequisite to decreasing the uncertainty of sampling rates. If the thermally stable sorbent additionally has a high sorptive capacity, it may be possible to design true kinetic samplers for most SVOCs. In the meantime, the passive air sampling community would benefit from being more transparent by rigorously quantifying and explicitly reporting uncertainty.

Halogenated and organophosphorous flame retardants in surface soils from an e-waste dismantling park and its surrounding area: Distributions, sources, and human health risks

Electronic waste (e-waste) dismantling is an important source of flame retardant emissions, and may have potentially adverse effects on surrounding area. This study investigated their influence on the surrounding area and the human health risks after an industrial park was built in 2015 and environmentally friendly technologies were introduced at an e-waste dismantling site in South China. The concentrations of flame retardants, including polybrominated diphenyl ethers (PBDEs), polybromobenzenes (PBBzs), Dechlorane plus (DP), and organophosphate esters (OPEs), in the soils were measured. The results showed that soil contamination was greater in the industrial park than in the surrounding area. The PBDE concentrations were the highest with BDE209, a daca-BDE, being the dominant congener, followed by OPEs, where triphenyl phosphate levels were the highest. Furthermore, triphenyl phosphate can be used as an indicator of flame retardant emissions during e-waste dismantling in this region. The f_anti value of DP was stable at around 0.75. The principal component analysis showed that direct emission was the major source of pollutants in the industrial park. The direct emission proportion decreased in the surrounding area, but migration and transformation increased. None of the chemicals posed a non-carcinogenic risks to children and adults via oral uptake or dermal contact when the absorption factors of the chemicals were included in the estimation. However, the total hazard quotients for children were close to a unit in the industrial park, of which, the PBDE and OPE proportions accounted for 84.2% and 15.8% of the total, respectively. However, the PBBz and DP percentages were negligible. Therefore, PBDEs and OPEs should be given more attention in the future.

Halogenated flame retardants in the sediments of the Chinese Yellow Sea and East China Sea

With the phasing out of traditional polybrominated diphenyl ethers (PBDEs), significant volumes of alternative brominated flame retardants (aBFRs) are being used and released into the environment compartment, especially in coastal regions. The levels and distribution of PBDEs, aBFRs, and dechlorane plus (DPs) were investigated in the surface sediments of the Yellow Sea (YS) and East China Sea (ECS) to examine the distribution and sources of these hydrophobic contaminants. The level and distribution of pollutants in the sediments of YS and ECS show obvious regional differences. As a major replacement for decabromodiphenyl ether (BDE 209), decabromodiphenyl ethane (DBDPE) was the dominant compound observed in the surface sediments, with a concentration one order of magnitude higher than that of BDE 209. High concentrations were found in the depositional zones of the YS, indicating that these contaminants may originate from land-based pollution sources (likely from the Laizhou Bay manufacturing base) near the Bohai Sea. The pollutants can be carried by the coastal current together with the sediment from the Yellow River, transported through the Bohai Strait and deposited in the mud zone of Northern and Southern YS. Low levels of halogenated flame retardants (HFRs) were found in the estuary of the Yangtze River and ECS, indicating that Yangtze River contributes less HFRs to the region. Riverine discharge, atmospheric deposition, surface runoff, ocean current system, and mud area deposition effects may be significant factors influencing the distributions of HFRs.

Source Apportionment of Fine-Particle, Water-Soluble Organic Nitrogen and Its Association with the Inflammatory Potential of Lung Epithelial Cells

Identifying the key chemical compounds and source contributions in ambient particles associated with the burden of cardiopulmonary disease is important to develop cost-effective air pollution mitigating strategies that maximize the protection of public health. To help address this need, we examined 109 daily ambient fine particulate matter samples (PM_2.5) that were collected in Beijing in one year. The samples were analyzed for chemical composition including organic and elemental carbons, metals, ions, as well as organic molecular markers. In addition, the secretion of pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured by exposing lung epithelial cells (A549) to water extracts of PM_2.5 samples. Single pollutant and constituent-PM_2.5 joint linear models were used to estimate the associations. Higher PM_2.5 mass and measured chemical components were found in cold seasons than in warm seasons due to the greater contributions of secondary inorganic sources, biomass burning, and coal combustion. Water-soluble organic nitrogen (WSON) had the strongest associations with levels of pro-inflammatory cytokines compared to PM_2.5 mass and other chemical species in both the one and constituent-PM_2.5 joint linear models. Our study is the first to highlight that ambient WSON from diverse sources dominates the inflammatory potential of lung epithelial cells.

Brominated flame retardants in atmospheric fine particles in the Beijing-Tianjin-Hebei region, China: Spatial and temporal distribution and human exposure assessment

Atmospheric fine particle (PM_2.5) samples were collected over a whole year (April 2016 - March 2017) across five sampling locations in the Beijing-Tianjin-Hebei (BTH) region, to investigate the occurrence of novel brominated flame retardants (NBFRs) and polybrominated diphenyl ethers (PBDEs). The concentrations of ∑₉NBFRs were in the range of 0.63-104 pg/m³ (15.6 ± 16.8 pg/m³) in atmospheric PM_2.5, while the levels of ∑₉PBDEs (excluding BDE-209) ranged from 0.05 to 19.1 pg/m³ (2.9 ± 3.8 pg/m³) and BDE-209 concentrations ranged from 0.88 to 138 pg/m³ (22 ± 28 pg/m³). Relatively higher levels of NBFRs and PBDEs were found at urban sampling sites in Beijing City and Shijiazhuang City. Decabromodiphenylethane (DBDPE) and BDE-209 were the dominant compounds with the relative abundances of 72% in ∑₉NBFRs and 90% in ∑₁₀PBDEs, respectively. Generally, the levels of most target BFRs in summer were lower than those in other seasons. However, there were no notable seasonal differences in levels of DBDPE and BDE-209 in atmospheric PM_2.5 samples across the BTH region. Significant and positive correlations were found between the concentrations of BFRs and PM_2.5. Daily human exposure via inhalation revealed that children have a higher probability of suffering from the adverse effects of BFRs than that of adults. In addition, residents living near sampling locations across the BTH region may suffer high exposure risks to BDE-209 and NBFRs.

Selected organohalogenated flame retardants in Egyptian indoor and outdoor environments: Levels, sources and implications for human exposure

There is scant information on the presence of the polybrominated diphenyl ethers (PBDEs) and other alternative flame-retardants (NFRs) in Africa. Hence, to investigate their levels, sources, and human exposure scenarios, elevated fine dust (EFD) samples from apartments (n = 12), working places (n = 9) and cars (n = 12), floor dust (FD) samples (n = 5) and outdoor dust samples (n = 21) were collected from Alexandria, Egypt, during 2014. Gaseous concentrations were estimated using low density polyethylene sheets (n = 33 and 21 for indoor and outdoor sites, respectively). Indoor gaseous and dust PBDE (7.0-300 pg/m³; 4.0-770 ng/g), and NFR (0.40-48 pg/m³; 0.50-8.5 ng/g) concentrations were significantly higher (p = 0.004-0.02) than outdoor concentrations (PBDEs: 3.0-41 pg/m³, 1.5-195 ng/g; NFRs: 0.20-13 pg/m³, 0.50-4.0 ng/g). Median PBDE concentration in cars (210 ng/g) was higher than in apartments and working places (130  ng/g respectively). PBDE concentrations in FD were 7.0-14-folds lower than EFD concentrations. Outdoor PBDE concentrations were significantly higher (p < 0.01) at residential-industrial places with older buildings. All samples were dominated by BDE-47 and 99. HBB, BTBPE and DDC-CO were the most abundant NFRs in EFD samples. Profiles of PBDE and NFR in FD closely matched those of outdoor dust, indicating a possible carryover from the outdoor environment. Although factors such as number of electronics, construction year and floor type significantly correlated with the majority of PBDE congeners and some NFRs in apartments and working places, sources were not clearly identified for NFRs. Significant log-linear relationships were obtained between theoretical and calculated dust-air partitioning coefficients for all samples indicating an equilibrium state between dust and vapor. Low possibility of occurrence of adverse health effects was concluded, with the inhalation pathway (for adults) and dust ingestion (for children) acting as the most important exposure routes.

Theoretical study on the reactions of a series of polybromobenzenes with OH radicals: mechanism, kinetics, and QSAR

Polybromobenzenes are a kind of monocyclic aromatic flame retardants that are used as a substitute for polybrominated diphenyl ethers and hexabromocyclododecane. In this paper, the reaction mechanism and rate constants for the reaction of OH radicals with a series of polybromobenzenes such as hexabromobenzene (HBB), 1,2,4,5-tetrabromobenzenes (1,2,4,5-TeBB), pentabromobenzene (PEBB), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), and 2,4,5-tribromotoluene (2,4,5-TrBT) have been investigated by quantum chemical method. The reaction mechanism was obtained at the MPWB1K/6-311+g(3df,2p)//MPWB1K/6-31+g(d,p) level of theory and the rate constants were deduced over the temperature range of 200–370 K using canonical variational transition state (CVT) theory with the small curvature tunneling (SCT) method. The rate constants of OH radicals with HBB, 1,2,4,5-TeBB, PEBB, PBEB, PBT, and 2,4,5-TrBT are determined to be 5.72 × 10−13, 1.23 × 10−12, 8.78 × 10−13, 9.23 × 10−13, 6.46 × 10−13, and 1.69 × 10−12, respectively, at 298 K and 1 atm. The estimated atmospheric lifetimes of HBB (20.08 days), 1,2,4,5-TeBB (9.65 days), PEBB (13.5 days), PBEB (12.9 days), PBT (18.4 days), and 2,4,5-TrBT (7.0 days) determined by OH radicals indicate that polybromobenzenes have the potential for long-range transport. The genetic function approximation is used to study the quantitative structure–activity relationship. The coefficients indicate that the ELUMO has the highest correlation to logkOH.

From headwaters to estuary: Distribution and fate of halogenated flame retardants (HFRs) in a river basin near the largest HFR manufacturing base in China

With the gradual phasing out of polybrominated diphenyl ethers (PBDEs), market demands for alternative halogenated flame retardants (HFRs) are increasing. The Laizhou Bay area is the biggest manufacturing base for brominated flame retardants (BFRs) in China, and the Xiaoqing River is the largest and most heavily contaminated river in this region. Water and sediment samples were collected from the headwaters to the estuary of the Xiaoqing River to investigate the distribution and fate of HFRs [i.e., PBDEs, alternative brominated flame retardants (aBFRs) and dechlorane plus (DPs). In the water samples, DPs was the most abundant flame retardant (median: 11.7ng/L), followed by decabromodiphenylethane (DBDPE) (5.92ng/L). In the sediment samples, DBDPE was the predominant flame retardant (39.5ng/g dw), followed by decabromodiphenyl ether (BDE 209) (2.81ng/g dw). The levels of DBDPE exceeded those of BDE 209 in most samples, indicating the overwhelming replacement of BDE 209 by DBDPE in this area. In the river section of this study, point source and atmospheric deposition followed by land runoff were the major factors influencing the distribution of HFRs, whereas in the estuary, riverine discharge, the estuarine maximum turbidity zone (MTZ), and hydrodynamic parameters played more important roles. Manufacturing is a significant source of contamination of the Xiaoqing River basin through atmospheric deposition and wastewater discharge.

Occurrence and Source Effect of Novel Brominated Flame Retardants (NBFRs) in Soils from Five Asian Countries and Their Relationship with PBDEs

This paper presents the first comprehensive survey of 19 novel brominated flame retardants (NBFRs) in soil samples collected among five Asian countries. High variability in concentrations of all NBFRs was found in soils with the geometric mean (GM) values ranging from 0.50 ng/g dry weight (dw) in Vietnam to 540 ng/g dw in the vicinity of a BFR manufacturer in China. In urban, rural, and background locations, the GM concentrations of ∑₁₉NBFRs decreased in the order of Japan > South Korea > China > India > Vietnam. Correlations among different NBFR compounds were positive and statistically significant (p < 0.05), suggesting that they originate from similar sources. Evidence for simultaneous application between polybrominated diphenyl ethers (PBDEs) and NBFRs were also noted. Principal component analysis of NBFR concentrations revealed specific pollution sources for different NBFRs coming from urban, BFR-related industrial, and e-waste sites. For the first time, this study demonstrates a "point source fractionation effect" for NBFRs and PBDEs. The concentrations of all NBFRs and PBDEs were negatively and significantly correlated with the distance from BFR-related industrial and e-waste regions. Positive and significant correlation between population density and NBFR concentrations in soils was identified. Our study revealed that the primary sources effects were stronger than the secondary sources effects in controlling the levels and distribution of NBFRs and PBDEs in soils in these five Asian countries.

Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants (aBFRs) in sediments from four bays of the Yellow Sea, North China

The distribution characteristics and potential sources of polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants (aBFRs) were investigated in 54 surface sediment samples from four bays (Taozi Bay, Sishili Bay, Dalian Bay, and Jiaozhou Bay) of North China's Yellow Sea. Of the 54 samples studied, 51 were collected from within the four bays and 3 were from rivers emptying into Jiaozhou Bay. Decabromodiphenylethane (DBDPE) was the predominant flame retardant found, and concentration ranged from 0.16 to 39.7 ng g(-1) dw and 1.13-49.9 ng g(-1) dw in coastal and riverine sediments, respectively; these levels were followed by those of BDE 209, and its concentrations ranged from n.d. to 10.2 ng g(-1) dw and 0.05-7.82 ng g(-1) dw in coastal and riverine sediments, respectively. The levels of DBDPE exceeded those of decabromodiphenyl ether (BDE 209) in most of the samples in the study region, whereas the ratio of DBDPE/BDE 209 varied among the four bays. This is indicative of different usage patterns of brominated flame retardants (BFRs) and also different hydrodynamic conditions among these bay areas. The spatial distribution and composition profile analysis indicated that BFRs in Jiaozhou Bay and Dalian Bay were mainly from local sources, whereas transport from Laizhou Bay by coastal currents was the major source of BFRs in Taozi Bay and Sishili Bay. Both the ∑PBDEs and ∑aBFRs (sum of pentabromotoluene (PBT), 2,3-diphenylpropyl-2,4,6-tribromophenyl ether (DPTE), pentabromoethylbenzene (PBEB), and hexabromobenzene (HBB)) were at low concentrations in all the sediments. This is probably attributable to a combination of factors such as low regional usage of these products, atmospheric deposition patterns, coastal currents transportation patterns, and degradation processes for higher BDE congeners. This paper is the first study that has investigated the levels of DBDPE in the coastal sediments of China's Yellow Sea.

Polybrominated diphenyl ethers and new polybrominated flame retardants in tree bark from western areas of China

Tree bark samples were collected from 15 sites across western China in 2013, and the polybrominated diphenyl ether (PBDE) and new polybrominated flame retardant (NBFR) concentrations in the samples were determined. The mean total PBDE concentration was 51.8 ng/g lipid weight, which was 85.2% to 99.4% lower than in Chinese eastern coastal areas and the E-waste recycling areas. The dominant PBDE congener was BDE209, and its mean concentration was 49 ng/g lipid weight. The mean 2,3,5,6-tetrabromo-p-xylene, pentabromobenzene, pentabromotoluene, and hexabromobenzene concentrations were 0.61 ng/g, 0.97 ng/g, 0.68 ng/g, and 0.68 ng/g lw, respectively. The PBDE and NBFR concentrations in the air at the sampling sites were estimated from the concentrations in the tree bark samples. The estimated mean total PBDE and total NBFR concentrations in air were 58.5 pg/m(3) and 2.76 pg/m(3) , respectively. The sources of NBFR emissions were found to be different from the sources of PBDE emissions, as no relationship was found between the NBFR and PBDE concentrations, and it appeared that sources of measured hexabromobenzene, pentabromobenzene, and pentabromotoluene in tree bark in western China include industrial activity related to the aluminum industry. Environ Toxicol Chem 2016;35:1364-1370. © 2015 SETAC.

Brominated flame retardants in food and environmental samples from a production area in China: concentrations and human exposure assessment

Human exposure to brominated flame retardants (BFRs: decabromodiphenyl ether (BDE209), decabromodiphenyl ethane (DBDPE), hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), 1,2,3,4,5-pentabromobenzene (PBBz), and 2,3,5,6-tetrabromo-p-xylene (TBX)) in a brominated flame retardant production area (Weifang, Shandong Province, China) was estimated. Thirty food samples, 14 air samples, and 13 indoor dust samples were analyzed. BDE209 and DBDPE were the dominant BFRs in all samples. Higher alternative brominated flame retardant (including DBDPE, HBB, PBEB, PBT, PBBz, and TBX) concentrations were found in vegetables than in fish and meat; thus, plant-original foods might be important alternative BFR sources in the study area. The BDE209 and alternative BFR concentrations in air were 1.5×10(4) to 2.2×10(5) and 620 to 3.6×10(4) pg/m3, respectively. Mean total BFR exposures through the diet, inhalation, and indoor dust ingestion were 570, 3000, and 69 ng/d, respectively (16, 82, and 2% of total intake, respectively). Inhalation was the dominant BFR source except for DBDPE, for which diet dominated. BDE209 contributed 85% of the total BFR intake in the study area.

Levels, spatial distribution, and exposure risks of decabromodiphenylethane in soils of North China

Eighty-seven soil samples collected from North China were analyzed for decabromodiphenyl ethane (DBDPE). The concentrations of DBDPE ranged from undetectable to 1612 ng/g, with the highest concentration present in Shandong. Additionally, the mean concentration of DBDPE in Shandong was found to be onefold higher than those found in Hebei and Shanxi, likely due to DBDPE production in Shandong. Relatively high concentrations of DBDPE in soils were also present in the south of Tianjin, where e-waste recycling may provide a source in this region. The fractions of DBDPE [DBDPE/(DBDPE + BDE209)] were lower than 0.5 in most soil samples, in agreement with the fact that deca-BDE is currently the main additive in brominated flame retardants (BFR) used in China. An obvious decreasing trend in DBDPE concentrations from east to west in North China was noted, with relatively higher DBDPE concentrations present in Shandong. A soil ingestion exposure assessment showed that for most sites, soil ingestion EDI was slightly lower than inhalation EDI; exceptions were found in several polluted sites, where soil ingestion was a more significant exposure route.

Concentrations and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (NPAHs) in the atmosphere of North China, and the transformation from PAHs to NPAHs

The occurrence of polycyclic aromatic hydrocarbons (PAHs) and nitrated derivatives (NPAHs), as well as their transformation may have significant health impacts on humans. To investigate the level, spatial distribution and the transformation process of PAHs and NPAHs in North China, we performed a griddedfield passive air sampling campaign in summer of 2011. The median concentration of 25 PAH congeners and 13 NPAHs was 294 ng m(-3) (or 26.7 mg sample(-1)) and 203 ng sample(-1), respectively. Relative higher level of PAHs in Shanxi Province and NPAHs in megacities was observed. In North China, coal/biomass combustion and photochemical formation was the predominant source of PAHs and NPAHs, respectively.To investigate the relationship between these pollutants, a model incorporating NPAHs, PAHs and NO(2) was established, and the result indicated that NO(2) will promote the transformation processes from PAHs to NPAHs, which may increase the total toxicity of PAH-NPAH mixtures.

Thermochemical factors affecting the dehalogenation of aromatics

Halogenated aromatics are one of the largest chemical classes of environmental contaminants, and dehalogenation remains one of the most important processes by which these compounds are degraded and detoxified. The thermodynamic constraints of aromatic dehalogenation reactions are thus important for understanding the feasibility of such reactions and the redox conditions necessary for promoting them. Accordingly, the thermochemical properties of the (poly)fluoro-, (poly)chloro-, and (poly)bromobenzenes, including standard enthalpies of formation, bond dissociation enthalpies, free energies of reaction, and the redox potentials of Ar-X/Ar-H couples, were investigated using a validated density functional protocol combined with continuum solvation calculations when appropriate. The results highlight the fact that fluorinated aromatics stand distinct from their chloro- and bromo- counterparts in terms of both their relative thermodynamic stability toward dehalogenation and how different substitution patterns give rise to relevant properties, such as bond strengths and reduction potentials.