Polybrominated diphenyl ethers in surface sediments from principal watersheds of Shanghai, China: levels, distribution, influencing factors, and risk assessment

A critical review on BDE-209: Source, distribution, influencing factors, toxicity, and degradation

As the most widely used polybrominated diphenyl ether, BDE-209 is commonly used in polymer-based commercial and household products. Due to its unique physicochemical properties, BDE-209 is ubiquitous in a variety of environmental compartments and can be exposed to organisms in various ways and cause toxic effects. The present review outlines the current state of knowledge on the occurrence of BDE-209 in the environment, influencing factors, toxicity, and degradation. BDE-209 has been detected in various environmental matrices including air, soil, water, and sediment. Additionally, environmental factors such as organic matter, total suspended particulate, hydrodynamic, wind, and temperature affecting BDE-209 are specifically discussed. Toxicity studies suggest BDE-209 may cause systemic toxic effects on living organisms, reproductive toxicity, embryo-fetal toxicity, genetic toxicity, endocrine toxicity, neurotoxicity, immunotoxicity, and developmental toxicity, or even be carcinogenic. BDE-209 has toxic effects on organisms mainly through epigenetic regulation and induction of oxidative stress. Evidence regarding the degradation of BDE-209, including biodegradation, photodegradation, Fenton degradation, zero-valent iron degradation, chemical oxidative degradation, and microwave radiation degradation is summarized. This review may contribute to assessing the environmental risks of BDE-209 to help develop rational management plans.

Unveiling the occurrence, distribution, removal, and environmental impacts of 65 emerging contaminants in neglected fresh leachate from municipal solid waste incineration plants

Emerging contaminants (ECs) are commonly found in environmental media. Yet leachate from municipal solid waste incineration plants (MSWIPs), which can serve as a reservoir for various contaminants, including ECs, has received little investigation. To address this gap, 65 ECs were analyzed in the fresh leachate and biological effluent from three major MSWIPs in Shanghai. Results indicated that over half (56%) of the 65 ECs were detected in fresh leachate. Different ECs would be removed to varying degrees after biological treatment, including polycyclic aromatic hydrocarbons (PAHs) (65%), polybrominated diphenyl ethers (PBDEs) (51%), phthalate esters (PAEs) (36%), and organophosphorus pesticides (OPPs) (34%). Notably, for tetrabromobisphenol A (TBBPA), a PBDE substitute, only 2% was removed after biological treatment, while polychlorinated biphenyls (PCBs) were effectively removed at 83%. Water solubility and the octanol-water partition coefficient are key factors influencing the distribution and removal of ECs in leachate. the effluent will still contain refractory ECs even after the biological treatment. These residual ECs discharged to sewers can impact wastewater treatment plants or contaminate surface water and groundwater. These findings provide insights into the leachate contamination by ECs, their environmental fate, factors affecting their behavior, and potential environmental impacts.

Spatial monitoring and health risk assessment of polybrominated diphenyl ethers in environmental matrices from an industrialized impacted canal in South Africa

This study investigates the pollution of Markman stormwater runoff, which is a tributary to Swartkops River Estuary. Solid-phase and ultrasonic extraction methods were utilized in the extraction of water and sediment samples, respectively. The pH of the sampling sites was above the EU guideline. The ranges of concentration of [Formula: see text]PBDE obtained in water and sediment samples for all the seasons were 58.47-1357 ng/L and 175-408 ng/g, respectively. Results also showed that BDE-66 was the dominant congener, specifically in the industrial zone, where its concentrations ranged from 2 to 407 ng/g in sediment. Consequently, the high concentration of BDE- 66 in the sediment of stormwater calls for concern. Penta-BDE suggests potential moderate eco-toxicological risk, as evident in the calculated risk assessment. The result showed possible photodegradation along the contaminant's travel time, as only 7% of the PBDE was detected at the point of entry into the Swartkops River Estuary. Markman stormwater may be contributing heavily to the pollution load of Swartkops River, as evident in the alarming concentrations of PBDEs obtained. The industries at this zone should eliminate the contaminants before discharging their effluents into the canal.

Exposure to BDE-47 and BDE-209 impaired antioxidative defense mechanisms in Brachionus plicatilis

Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants (POPs) that pose serious challenges to aquatic animals and environments. Compared with BDE-47 which was one of the most toxic congeners known to date, BDE-209 is less toxic with higher abundance in biotic and abiotic samples. In this study, we have explored the effects of BDE-47 and BDE-209 at different concentrations on the radical oxygen species (ROS) levels and the antioxidant defense system of Brachionus plicatilis. Antioxidant indexes were measured, including total protein content (TSP), the activities of antioxidant enzymes, lipid peroxidation and DNA damage. The results indicated that while low concentrations of PBDEs could activate the antioxidant defense mechanisms, prolonged exposure to higher concentrations of PBDEs could impair the antioxidative capacity of B.plicatilis (P < 0.05). The overwhelming of the B.plicatilis antioxidant defense mechanism led to an accumulation of free radicals, resulting in the overactivation of lipid peroxidation and the increased frequency of DNA damage (P < 0.05). By studying the toxicity of PBDEs and the detoxification mechanism of B.plicatilis, our research has revealed useful indexes for detecting and monitoring the level of BDE-47 and BDE-209 in the future. Altogether, this study holds immense value in the field of ecotoxicology and environmental safety and will aid in the proper management of PBDEs pollution.

Pollution level, spatial distribution, and congener fractionation characteristics of low-brominated polybrominated diphenyl ethers (PBDEs) in sediments around Chaohu Lake, China

As new persistent organic compounds, polybrominated diphenyl ethers (PBDEs) have aroused important concern because of their potential bioaccumulation and possible ecological and health risk. To examine the sources and temporal variation of PBDEs in Chaohu Lake in eastern China, the surface sediments from Nanfei River (NFR) and core sediments from four estuaries were measured. It showed that low-brominated congeners were dominant, from MonoBDEs to HeptaBDEs (referred to as Σ₃₉PBDE). Concentrations of ∑₃₉PBDE and the ratios of (BDE-47 + BDE-99 + BDE-100)/(BDE-153 + BDE-154) were much greater in surface sediments than in core sediments. The highest concentration was observed in a site close to the outfall of a municipal sewage treatment plant (MSTP), and the ratio was significantly correlated with ∑₃₉PBDE. These results suggested that PentaBDE and OctaBDE commercial mixtures were widely used around Chaohu Lake and the effluent of municipal sewage was a dominant source of PBDEs to surface sediment. Compared to data from other freshwater systems around the world, the concentrations of BDE-47 and BDE-99 in this study were in the middle of the range of global data, but BDE-183 concentrations were at the high end of the range. Due to restrictions on the usage of PentanBDE and OctaBDE commercial mixtures, reductions of PBDE levels from subsurface to superficial layer were observed in all estuaries. Elevated contribution by MonoBDEs to ∑₃₉PBDE in the estuary of the only outflow river suggests significant congener fractionation. TriBDEs, TetraBDEs, and HexaBDEs appeared to pose low risks in all surface sediments, but moderate to high risks may be expected for PentaBDEs. Overall, the results would contribute to a better understanding of the sources and environmental fate of PBDEs in the studied eutrophicated lake.

Comprehensive evaluation of the toxicity of the flame retardant (decabromodiphenyl ether) in a bioindicator fish (Gambusia affinis)

In recent years, concerns have increased about the adverse effects on health and the environment of polybrominated diphenyl ethers (PBDEs), especially BDE-209, the most widely PBDE used globally. These pollutants derive from e-waste and present different adverse effects on biota. In this work, a toxicological study on mosquitofish (Gambusia affinis) using BDE-209 (2,2',3,3',4,4',5,'5',6,6'-decabromodiphenyl ether) was carried out. Acute toxicity bioassays were conducted with daily renewal of solutions, using different concentrations of environmental relevance, ranged between 10 and 100 μg L^-1 of BDE-209. At 48 and 96 h of exposure, several parameters were evaluated, such as mortality, individual activity (swimming), biochemical activity (catalase; thiobarbituric acid-reactive substances; and acetylcholinesterase), and cytotoxic responses (micronucleus frequencies). In addition, integrated biomarker response and multivariate analyses were conducted to study the correlation of biomarkers. The calculated Lethal Concentration-50 remained constant after all exposure times (24 to 96 h), being the corresponding value 27.79 μg L^-1 BDE-209. Furthermore, BDE-209 induced effects on the swimming activity of this species in relation to acetylcholine, since BDE-209 increased, producing oxidative damage at the biochemical level and genotoxicity after 48 h of exposure to 10 and 25 μg L^-1 BDE-209. The results indicate that BDE-209 has biochemical, cytotoxic, neurotoxic, and genotoxic potential on G. affinis. In addition, mosquitofish could be used as a good laboratory model to evaluate environmental stressors since they could represent a risk factor for Neotropical species.

Occurrence and Risk Assessment of Polybrominated Diphenyl Ethers in Surface Water and Sediment of Nahoon River Estuary, South Africa

The concentrations, potential sources, and compositional profile of PBDEs in the surface water and sediment of Nahoon Estuary, East London, South Africa, were investigated with solid-phase extraction and ultra-sonication, respectively, followed by gas-chromatography-electron capture detection. The seasonal range of the contaminants’ concentrations in water and sediment samples in spring season were ∑PBDE 329 ± 48.3 ng/L (25.32–785 ng/L) and ∑PBDE 4.19 ± 0.35 ng/g dw (1.91–6.57 ng/g), but ∑PBDE 62.1 ± 1.50 ng/L (30.1–110 ng/L) and ∑PBDE 65.4 ± 15.9 ng/g dw (1.98–235 ng/g) in summer, respectively. NH1 (first sampling point) was the most contaminated site with PBDE in the Estuary. The potential source of pollution is attributed to the stormwater runoff from a creek emptying directly into the Estuary. This study’s dominant PBDE congener is BDE-17, ranging from below detection limit to 247 ng/L and 0.14–32.1 ng/g in water and sediment samples, respectively. Most detected at all the sites were BDE-17, 47, 66, and 100. Most BDE-153 and 183 are found in sediment in agreement with the fact that higher brominated congeners of PBDE adsorb to solid materials. There was no correlation between the congeners and organic carbon and organic matter. However, the human health risk assessment conducted revealed that the PBDE concentration detected in the estuary poses a low eco-toxicological risk. Nevertheless, constant monitoring should be ensured to see that the river remains safe for the users, as it serves as a form of recreation to the public and a catchment to some neighbourhoods.

Spatiotemporal distribution, sources and ecological risks of perfluorinated compounds (PFCs) in the Guanlan River from the rapidly urbanizing areas of Shenzhen, China

Limited studies have demonstrated the environmental concerns of perfluorinated compounds (PFCs) in the rivers flowing through the rapidly urbanizing areas. Therefore, this study aims to investigate the spatial and temporal distribution, major sources and ecological risks of PFCs in the surface water samples, collecting from the Guanlan River, Shenzhen, China. The concentrations of ∑PFCs ranged from 11.3 to 384 ng/L, with a mean value of 81.8 ng/L in the dry season, and ranged from 6.90 to 619 ng/L, with a mean value of 339 ng/L in the wet season. Short-chain PFCs such as perfluorohexane sulfonate (PFHxS) and perfluorobutane sulfonate (PFBS) were detected as the predominant compounds. Further, the spatiotemporal distribution revealed significantly higher levels of PFCs in the wet season than those in the dry season, and relatively higher levels in the tributaries than those in the mainstream. Source apportionment highlighted the industrial discharges, domestic wastewater, precipitation, and wastewater treatment plants as the major sources of PFCs. Moreover, the population density and associated urban sewage emissions observed as important indicators for PFCs uneven distribution in the area. The ecological risk assessment revealed perfluorotetradecanoic acid (PFTA, C14) posed high ecological risks to the aquatic organisms (especially for mysid) in the Guanlan River. Taken all together, this study not only unveiled the characteristics of PFCs contamination in the rapidly urbanizing catchment, but also provided the baseline data for policy makers to protect the ecological environment of the urban rivers in the rapidly growing area.

Polybrominated diphenyl ethers (PBDEs) in soil and dust from plastic production and surrounding areas in eastern of China

Polybrominated diphenyl ethers (PBDEs) are a class of organic pollutants. They are used as flame retardants that caused worldwide environmental concern. This study investigated the occurrence of PBDEs in soils and dusts from three plastic manufacture plants and surrounding areas in Eastern China. A total of 13 PBDE congeners were detected using gas chromatography-mass spectrometer (electron impact ionization). The total concentrations of PBDEs range from 2.21 to 558, 19.7-4916, and 8.70-18,451 ng/g dry weight in the soils of three sampling areas, with mean of 1004 ng/g d w; in dusts, the concentrations range from 7240 to 10,469, 684-4482, and 193-3989 ng/g d w, with an overall mean of 3619 ng/g d w. The most abundant congener is the BDE-209, followed by BDE-153 and BDE-85. This indicates that the brominated flame retardant added in the plastic manufacture is mainly the commodity decabromodiphenyl ether. In comparison with other polluted areas around the world, the PBDE concentrations in the soils of the plastic manufacture plants are similar to those in soils of waste plastic disposal areas and PBDEs production sites, but orders of magnitude higher than those in agricultural soils, mountain soils and rural soils. Daily exposure was estimated using the average concentrations of the pollution sites. The hazard quotient shows that the PBDEs pose considerable human health risks, especially to children, to which attention should be paid.

The occurrence of polybrominated diphenyl ether (PBDE) contamination in soil, water/sediment, and air

As a kind of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are extensively used in different types of electronic equipment, furniture, plastics, and textiles. PBDEs are ubiquitous environmental contaminants that may impact human health and ecosystems. Here we highlight recent findings on the occurrence, contamination status, and transport of PBDEs in soil, water/sediment, and air. Four aspects are discussed in detail: (1) sources of PBDEs to the environment; (2) occurrence and transport of PBDEs in soil; (3) PBDEs in aquatic ecosystems (water/sediment) and their water-sediment partitioning; and (4) the occurrence of PBDEs in the atmosphere and their gas-particle partitioning. Future prospects for the investigation on PBDEs occurrence are also discussed based on current scientific and practical needs.

MP-UV/CaO2 as a pretreatment method for the removal of carbamazepine and primidone in waste activated sludge and improving the solubilization of sludge

Medium-pressure ultraviolet light (MP-UV) combined with calcium peroxide (CaO₂) as a pretreatment technology for removing carbamazepine (CBZ) and primidone (PMD) in waste active sludge (WAS) and improving the solubilization of sludge were investigated. CBZ and PMD were effectively removed and the removal fitted pseudo-first kinetics under MP-UV/CaO₂ treatment with R² > 0.97. The higher CaO₂ dosage and lower initial volatile suspended solids (VSS) concentration were conductive to the removal of CBZ and PMD. Of the CaO₂ hydrolysates, Ca(OH)₂ played a more important role than H₂O₂ during MP-UV/CaO₂ treatment. The removal of the target compounds was attributed to direct photolysis and indirect photolysis caused by •OH, ³DOM^*, and ¹O₂, in which •OH played a vital role with > 62.2% contribution to the overall degradation rate. A model predicting the steady concentration of •OH in WAS ([VSS] ≈ 8.6 g L^-1) under MP-UV/CaO₂ treatment with CaO₂ dosage ranging from 0 to 0.5 g g^-1-VSS was proposed and validated. Moreover, major intermediates of CBZ and PMD were detected and the probable transformation pathways during MP-UV/CaO₂ treatment were proposed. In addition, MP-UV/CaO₂ promoted the sludge solubilization effectively. Considering both the pharmaceutical degradation and sludge solubilization, the optimum operation condition with 0.2 g-CaO₂ g^-1-VSS combined with 7 h MP-UV irradiation is recommended. Under this condition, more than 92.3% of CBZ and 90.3% of PMD were removed, and soluble chemical oxygen demand (SCOD) increased by 657% and 13.6% compared with sole 10 h CaO₂ (0.2 g g^-1-VSS) treatment and 7 h MP-UV treatment, respectively.

Sublethal or not? Responses of multiple biomarkers in Daphnia magna to single and joint effects of BDE-47 and BDE-209

Polybrominated diphenyl ethers (PBDEs) are extremely incessant anthropogenic contaminants found in the environment, with dreadful risk to aquatic ecosystems. However, there is a limited amount of data concerning their impacts on freshwater organisms. 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) are significant components of total PBDEs in water. The sublethal effects of BDE-47, BDE-209 and their binary mixtures on the aquatic organism Daphnia magna were investigated in acute and chronic exposure experiments. Immobilization and heartbeat were studied in daphnids after 48 h of exposure. Mortality rate, breed number, Cholinesterase (ChE), Glutathione S-transferases (GST) and Catalase (CAT) activities were evaluated after 21 days of exposure. The results showed that at 100 and 200 μg/L concentration of BDE-47, immobilization rate of daphnids were inhibited by 44.0 ± 16.7% and 88.0 ± 10.9%, respectively. The binary mixture of BDE-47 and BDE-209 had uncongenial effects on immobilization of D. magna under acute toxicity test. BDE-209 significantly increased the heartbeat rate of daphnids, which increased even further when combined with BDE-47. After 21 days of exposure, daphnids exposed to single BDE-47 were physiologically altered. The combination of BDE-47 with BDE-209 significantly decreased the mortality rate of daphnids. Irrespective of the concentration, higher numbers of offsprings were produced in the mixtures compared to BDE-47 treatment alone. ChE activities significantly (p < 0.05) decreased at concentrations of 2 and 4 μg/L in single BDE-47 treatment, while GST activity significantly (p < 0.05) decreased at 0.5 μg/L. CAT activities significantly increased with BDE-47 treatments in all the tested concentrations (p < 0.05). The mixtures significantly affect ChE (p < 0.05), GST (p < 0.05) and CAT activities (p < 0.05). The results illustrated that the toxicity of the mixture of PBDE congeners exposed to aquatic organisms may have antagonistic effects. The 21 days chronic test in this study suggests that acute toxicity tests, i.e. 48-h tests, using Daphnia may lead to underestimation of risks associated with PBDEs, especially, BDE-209. Hence, there is a necessity to re-examine PBDE congeners' environmental risk in aquatic organisms.

Rapid debromination of polybrominated diphenyl ethers (PBDEs) by zero valent metal and bimetals: Mechanisms and pathways assisted by density function theory calculation

Polybrominated diphenyl ethers (PBDEs) undergo debromination when they were exposed in zerovalent metal or bimetallic systems. Yet their debromination pathways and mechanisms in these systems were not well understood. Here we reported the debromination pathways of three BDE congeners (BDE-21, 25 and 29) by nano-zerovalent iron (n-ZVI). All these BDE congeners have three bromine substituents that were located in ortho-, meta- and para-positions. Results demonstrated that BDE-21, 25 and 29 preferentially debrominate meta-, ortho- and para-bromines, respectively, suggesting that bromine substituent at each position (i.e. ortho-, meta- or para-) of PBDEs can be preferentially removed. Singly occupied molecular orbitals of BDE anions are well correlated with their actual debromination pathways, which successfully explain why these BDE congeners exhibit certain debromination pathways in n-ZVI system. In addition, microscale zerovalent zinc (m-ZVZ), iron-based bimetals (Fe/Ag and Fe/Pd) were also used to debrominate PBDEs, with BDE-21 as target pollutant. We found that the debromination pathways of BDE-21 in m-ZVZ and Fe/Ag systems are the same to those in n-ZVI system, but were partially different from those in Fe/Pd systems. The debromination of BDE-21 in Pd-H₂ system as well as the solvent kinetic isotope effect in single metal and bimetallic systems suggests that H atom transfer is the dominant mechanism in Fe/Pd system, while e-transfer is still the dominant mechanism in Fe/Ag system.

Distribution, accumulation, and potential risk of polybrominated diphenyl ethers in the marine environment receiving effluents from a sewage treatment plant

We investigated the effect of sewage treatment plant effluent on the distribution and accumulation of polybrominated diphenyl ethers (PBDEs) in the marine environment. PBDEs concentrations in seawater and surface sediments were within the ranges 1.58-6.94 ng/L and 2.18-307 ng/g dw, respectively. PBDE concentrations in sediments gradually decreased with increasing distance from inner bay including the sewage outfall. The contribution of effluent to PBDE distributions was very limited. The concentrations of PBDEs in sediment core decreased exponentially with increasing depth. PBDE concentrations in oysters were 4.7-37 ng/g lw. BDE-209 was the dominant congener in marine environmental samples receiving effluent. Estimated dietary exposures of PBDEs by seafood were 0.01-0.08 ng/kg body weight/day, which were more than six orders of magnitude lower than the reported levels of PBDEs with the no observable adverse effects. Hazard quotients demonstrated that, at present, PBDEs posed no potential risk to benthic organisms in the study area.

Distribution of PBDEs, HBCDs and PCBs in the Brisbane River estuary sediment

To date, very little or no data exist in literature for some brominated flame retardants (BFRs) and polychlorinated biphenyls in Queensland sediments. These pollutants were measured in the sediments along the Brisbane River estuary. The target compounds were regularly detected in measurable concentrations: PBDEs=33.3-97.8% (n=45), PCBs=94.1-100% (n=51) and HBCDs=79-98% (n=48). Consistently, >90% of the observed ∑₈PBDE concentration was attributed to BDE-209. Mean PBDE levels (ng/g dry wt.) were: 4.4±3.2 (∑₈PBDE) and 4.4±3.0 (BDE-209) across 22 sampling sites. The mean ∑₇PCB and ∑HBCD were 5.4±4.5 and 1.0±1.5ng/g dry wt. respectively. The 25% (α-HBCD), 8% (β-HBCD) and 67% (γ-HBCD) diastereoisomer contributions observed were consistent with values reported in the literature. Contaminant levels are fairly distributed along the River and were generally low compared to similar studies around the world.

The occurrence of endocrine disrupting compounds in off-shore sediments from the southern Baltic Sea

This paper presents the study on the occurrence and spatial distribution of polybrominated diphenyl ethers (PBDEs), butyltin compounds (BTCs), bisphenol A (BPA), and alkylphenols (APs) in sediments. The study focused mainly on off-shore surface sediments collected from the southern Baltic Sea. The pollutant concentrations were as follows: <LOQ-0.158 μg kg(-1) dw ∑9PBDEs, 0.02-1.06 μg kg(-1) dw BDE-209; <LOQ-20.13 μg Sn kg(-1) dw ∑BTCs and 2.7-1001 μg kg(-1) dw nonylphenols (NPs). The spatial distribution of the analyzed compounds was highly related to the organic matter content in the sediments. Only BDE-209 concentrations were the highest in sandy sediments collected near the point source of pollution. This suggests the fresh anthropogenic input of BDE-209 into the marine environment. The principal component analysis (PCA) confirms these observations-the distribution of ∑BTCs, NPs, and ∑9PBDEs was mainly determined by the physicochemical properties of the sediments, while the distribution of BDE-209 was also related to other factors, such as proximity to the pollution source. According to the environmental standards applied in this work, NPs, and to a lesser extent TBT, might pose a risk to aquatic life in the present study area as they occur in some sediments in concentrations higher than those that might cause adverse effects on biota.

Distribution of polybrominated diphenyl ethers and HBCD in sediments of the Hunhe River in Northeast China

Forty surface sediment samples from the Hunhe River in Northeast China were evaluated for contamination by polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The results showed that decabromodiphenyl ether (BDE-209) was the predominant congener, accounting for >98 % of PBDEs in all sediment. The concentrations of BDE-209 and HBCD ranged from 3.96 to 327 ng/g dry weight and 0.05 to 25.8 ng/g dry weight, respectively, suggesting that BDE-209 was more widely applied in the study area. The mean concentrations of BDE-209 and HBCD in the downstream portion of the Hunhe River (BDE-209 148 ng/g dry weight and HBCD 3.74 ng/g dry weight) were found to be relatively higher than those in the upstream portion of the Hunhe River and the Dahuofang Reservoir, revealing an association with municipal sewage and industrial effluent received from the cities of Fushun and Shenyang. γ-HBCD was the most abundant diastereoisomer of all three analyzed HBCD isomers; however, marked elevations of α-HBCD were also found in most sediment samples. Surprisingly, the relative abundance (mean 38%) of α-HBCD in sediment from the upstream portion of the Hunhe River was significantly higher (p < 0.006, t test) than those in Dahuofang Reservoir (mean 24%). Moreover, the severe heavy metal contamination associated with the frequent mining activities in this region was tentatively suggested as being responsible for the increased levels of α-HBCD.

Using population demographic parameters to assess impacts of two polybrominated diphenyl ethers (BDE-47, BDE-209) on the rotifer Brachionus plicatilis

Polybrominated diphenyl ethers (PBDEs) are highly persistent anthropogenic contaminants found in the environment, posing a risk to aquatic ecosystems, whereas there is a lack of data concerning their impacts on marine invertebrates. The objective of this study was to assess the relative lethal and sublethal aquatic toxicity effects of two PBDEs, BDE-47 and BDE-209 congeners, on marine zooplankton rotifer Brachionus plicatilis associated with PBDE concentrations and time of exposure. Gas chromatography-mass spectrometry (GC-MS) analyses were performed to determine actual PBDE concentrations. Rotifer population demographic parameters from life tables, including age-specific survivorship (lx), age-specific fecundity (mx), net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), life expectancy (E0) and generation time (T), were used as measures of treatment effects. Results from this study have revealed increasingly intense negative effects on many of the rotifer demographic parameters with elevated PBDE concentrations. The population growth curves of B. plicatilis showed almost no lag phase and reached peak abundances within 11 days, while B. plicatilis exposed to BDE-209 had a lag phase of about 5 days. In addition, increased PBDE levels reduced the population abundances and peak population densities of B. plicatilis. The two PBDEs have caused the carrying capacity (K) suppressed and the negative influence turned more serious as the concentration rose. Results also revealed that the time to reach growth curve inflection point (Tp) was shortened by PBDEs to different degrees. This study not only indicated that life table demography and population growth curve studies were two important aspects used to evaluate toxicant PBDE effects, but also compared the two PBDE disruptions to the population growth and reproduction of the rotifer.

Hexabromocyclododecane diastereoisomers in surface sediments from river drainage basins of Shanghai, China: occurrence, distribution, and mass inventory

Concentrations of hexabromocyclododecanes (HBCDs) were determined in surface sediments of Shanghai, China. The concentrations of total HBCD diastereoisomers (ΣHBCD) ranged from 0.01 to 13.70 ng g(-1) dry weight (dw) with a mean value of 3.41 ng g(-1) dw, which was up to several orders of magnitude lower than those reported for sediments from European countries. The ΣHBCD concentrations in sediments from chemical/textile industrial or densely populated areas were generally higher than those from rural or less chemical/textile industrialized areas in Shanghai. A high proportion of α-HBCD was observed in sediment samples and was significantly higher than that of commercial HBCD products. This might be due to thermal isomerization from γ-HBCD to α-HBCD and slower degradation rate of α-HBCD compared to γ-HBCD in anaerobic conditions. The mass inventory of ΣHBCD in surface sediments of Shanghai was estimated at 164.4 kg, representing a significant source of HBCDs to the Shanghai environment. This indicates that further study on potential transfer of HBCDs from sediments to aquatic organisms and ecological risk assessments is required.

Occurrence, profiles, and ecological risks of polybrominated diphenyl ethers (PBDEs) in river sediments of Shanghai, China

Fifty-two PBDE congeners in river sediments from Shanghai were analyzed in the present study. The concentrations of Σ51PBDEs (defined as the sum of 51 BDE congeners except BDE209) and BDE209 ranged from 0.231 to 119 ng g(-1) and from nd to 189 ng g(-1), respectively. The most abundant BDE congeners in surface sediments were BDE118, 207, 208, 99, 49, 75, 47, 71 and 209, with median values of 1.67, 1.81, 1.83, 1.87, 1.98, 2.52, 2.73, 4.62 and 45.7 ng g(-1) dw, respectively. The concentrations of Σ52PBDEs were significantly correlated with total organic carbon (TOC) content in sediments (p < 0.05). Weak correlations between all PBDE homologues and TOC (r < 0.32) suggest that TOC had a little influence on sediment PBDE transport and distribution patterns in river sediments of Shanghai. Correspondence analysis (CA) showed that PBDEs in sediments in the studied area originated from commercial BDE formulations, combustion emission sources, and debromination of highly brominated PBDEs by aerobic/anaerobic microbes or sunlight. Risk assessment based on risk quotients (RQ) showed that PBDEs in all river sediments collected from Shanghai posed a high potential ecological risk (RQ > 1) to the sediment dwelling organisms, and pentaBDE, decaBDE and tetraBDE were the major ecological risk drivers.

Concentrations and risk assessment of polychlorinated biphenyls and polybrominated diphenyl ethers in surface sediments from the East Lake, China

The concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in surface sediment samples collected from the East Lake, China in winter 2012 and summer 2013 were analyzed in this study. The total PCB and PBDE concentrations ranged from not detected to 107.1 ng g(-1) dw and from 9.7 to 151.3 ng g(-1) dw, respectively. PCB-28, 101 and 180 were dominant congeners in both winter and summer. BDE-28 (44 %) was the dominant congener in winter and summer, followed by BDE-99 (28 %) and BDE-47 (26 %). The concentrations of PCBs in the sediment samples collected in summer were higher than those in winter, while the concentrations of PBDEs did not show much seasonal variations. Source analysis showed that the PCBs probably originated from urban runoff, industrial pollution and atmospheric deposition, and the PBDEs probably originated from historical usage of penta-BDE mixtures. Potential eco-toxicological risks caused by PCBs were found in about 5 % of the sampling sites; PBDEs had moderate eco-toxicological risk in 80 % sampling sites in the East Lake, China.

Hexabromocyclododecanes in surface sediments from Shanghai, China: spatial distribution, seasonal variation and diastereoisomer-specific profiles

The concentrations, spatial distribution, diastereoisomer-specific profiles of hexabromocyclododecanes (HBCDs) in surface sediments from three major rivers in Shanghai as well as the seasonal variation of HBCDs were investigated. The concentrations of total HBCD diastereoisomers ranged from 0.05 to 6.87ngg(-1)dw. Significant spatial distribution of total HBCDs concentrations were observed. The mean concentration of total HBCDs followed the order of Suzhou Creek (2.00ngg(-1))>Huangpu River (1.59ngg(-1))>Yunzao Creek (0.77ngg(-1)). The concentration was a relatively low HBCDs level compared to levels measured in domestic and other parts of the world. The proportions of α-HBCD in sediment samples were generally higher than that of commercial formulations. This might be due to thermal isomerization from γ-HBCD to α-HBCD and slower degradation rate of α-HBCD compared to γ-HBCD in anaerobic conditions. The concentrations of ΣHBCD in the summer were significantly higher than those in the winter (paired t test, p<0.01). This seasonal variation could probably be attributed to a combined effect of temperature and wet deposition. Moreover, a poor and no significant correlation between ΣHBCD levels and TOC content in sediments was observed, suggesting that the spatial distributions of HBCDs were not constrained by the TOC in sediments of Shanghai.

Effects of BDE-209 contaminated sediments on zebrafish development and potential implications to human health

Polybrominated diphenyl ethers are compounds widely used as flame-retardants, which are of increasing environmental concern due to their persistence, and potential adverse effects. This study had two objectives. First, we assessed if BDE-209 in sediment was bioavailable and bioaccumulated into zebrafish embryos. Secondly, we assessed the potential impact on human and environmental health of bioavailable BDE-209 using human in vitro cell assays and zebrafish embryos. Zebrafish were exposed from 4h to 8days post-fertilization to sediments spiked with 12.5mg/kg of BDE-209. Zebrafish larvae accumulated ten fold more BDE-209 than controls in unspiked sediment after 8days. BDE-209 impacted expression of neurological pathways and altered behavior of larvae, although BDE-209 had no visible affect on thyroid function or motoneuron and neuromast development. Zebrafish data and in silico predictions suggested that BDE-209 would also interact with key human transcription factors and receptors. We therefore tested these predictions using mammalian in vitro assays. BDE-209 activated human aryl hydrocarbon receptor, peroxisome proliferator activating receptors, CF/b-cat, activator protein 1, Oct-MLP, and the estrogen receptor-related alpha (ERRα) receptor in cell-based assays. BDE-209 also inhibited human acetylcholinesterase activity. The observation that BDE-209 can be bioaccumulated from contaminated sediment highlights the need to consider this as a potential environmental exposure route. Once accumulated, our data also show that BDE-209 has the potential to cause impacts on both human and environmental health.

Occurrence of hydrophobic organic pollutants (BFRs and UV-filters) in sediments from South America

In the present study the occurrence of emerging hydrophobic organic pollutants in sediment samples from South America (Chile and Colombia) was investigated for the first time. Nineteen Chilean and thirteen Colombian sediment samples were analyzed in order to determine their content of brominated flame retardants (BFRs) (including PBDEs and emerging BFRs) as well as UV filters (UV-F). Samples were collected from neighboring aquatic ecosystems highly urbanized and industrialized in Colombia (Magdalena River area) and Chile (Biobio region). Different analytical procedures were applied depending on the selected analytes, based on chromatographic and mass spectrometric methodologies (GC-MS and LC-MS-MS). In general, concentration levels of both BFRs (up to 2.43 and 143ngg(-1) dw of PBDEs in Chile and Colombia, respectively) and UV-F (nd-2.96 and nd-54.4ngg(-1) dw in Chile and Colombia, respectively) were in the low range of published data, and the contribution of BFRs was higher than that of UV-F for almost all the sampled sediments.