Polybrominated diphenyl ethers in dissolved and suspended phases of seawater and in surface sediment from Jiaozhou Bay, North China

Assessment of parent and alkyl -PAHs in surface sediments of Iranian mangroves on the northern coast of the Persian Gulf: Spatial accumulation distribution, influence factors, and ecotoxicological risks

Spatial patterns, potential origins, and ecotoxicological risk of alkylated (APAH) -and parent -(PPAH) polycyclic aromatic hydrocarbons (PAHs) were studied in mangrove surface sediments along the northern coasts of the Persian Gulf, Iran. The mean total concentrations (ngg-1dw) ∑32PAH, ∑PPAHs and ∑APAHs in sediments were 3482 (1689-61228), 2642 (1109-4849), and 840 (478-1273), respectively. The spatial variability was similar among these PAH groups, with the highest levels occurring in Nayband National Marine Park (NNMP). Physicochemical environmental factors, such as sediment grain size, and total organic carbon (TOC) contents, are significant factors of PAH distribution. These findings suggest that PAH pollution level is moderate-to-high, supporting the current view that mangrove ecosystems are under intensive anthropogenic impacts, such as petrochemical, oil and gas loads, port activities, and urbanization. Non-parametric multidimensional scaling (NPMDS) ordination demonstrated that NNMP mangrove is the critical site exhibiting high loading of PAH pollutants. Here, for the first time in this region, Soil quality guidelines (SQGs), Toxic equivalency quotient (TEQ), Mutagenic equivalency quotient (MEQ), and composition indices comprising Mean maximum permissible concentration quotient (m-MPC-Q), and Mean effect range median quotient (m-ERM-Q) methods were used to have a comprehensive risk assessment for PAH compounds and confirmed medium-to-high ecological risks of PAHs in the study area, particularly in the western part of the Gulf, highlighting the industrial impacts on the environment.

Effect of hydrodynamic and ecosystem conditions on persistent organic pollutant temporal-spatial variations in the Yellow Sea

Coastal seas are important pools of persistent organic pollutants (POPs) discharged from land. Considering the complex conditions in coastal seas and various biochemical features of POPs, special temporal-spatial variations in POPs have been reported. To understand these variations, we developed a three-dimensional hydrodynamic-ecosystem-POP coupled model and applied it to the Yellow Sea. We selected two POP species (polychlorinated biphenyl congener 153 (PCB-153) and decabromodiphenyl ether (BDE-209)), which have different biochemical properties, as target materials. The dissolved PCB-153 simulated concentration was high in late spring and low in autumn, whereas that of BDE-209 was high in summer and low in winter. Both PCB-153 and BDE-209 showed high particle-bound concentrations in early spring. In summer, dissolved PCB-153 accumulated at the sea bottom, whereas dissolved BDE-209 accumulated at the sea surface. Seasonal and spatial variation differences in the two POPs are likely caused by greater Henry's Law Constant (H') and bioconcentration factor (BCF) of PCB-153 than that of BDE-209, which leads to higher volatilization and stronger absorption by the particles for PCB-153 than BDE-209. As a component of such differences, the "biological pump" of PCB-153 in the central Yellow Sea is more apparent than that of BDE-209.

Dynamic modeling of the occurrence, sources, and environmental behavior of polybrominated diphenyl ethers in Zhelin Bay, China

This study analyzed polybrominated diphenyl ethers (PBDEs) in Zhelin Bay, China, investigating their occurrence, sources, and environmental behavior. PBDE congeners were detected in all sampled media. The Σ13PBDE concentrations in the dissolved phase ranged from 1.04 to 41.40 ng/L, while the concentrations ranged in suspended particulate matter from 0.02 to 12.56 ng/L. In sediments, PBDE concentrations ranged from 1.41 to 8.57 ng/g. The higher proportion of PBDEs in the dissolved phase in the bay than in the estuary is attributable to the type of PBDE products used in the aquacultural process in Zhelin Bay. Moreover, correlation analysis between PBDE concentrations and environmental parameters showed that the primary factor influencing PBDE concentrations in Zhelin Bay sediments may shift from riverine inputs to aquaculture. Principal component analysis and positive matrix factorization revealed that PBDEs in the water of Zhelin Bay primarily originated from the degradation of octa-BDE, deca-BDE, and penta-BDE products employed in aquaculture. In contrast, the PBDEs in Zhelin Bay sediments mainly originated from riverine inputs. In addition, a level IV dynamic fugacity-based multimedia model was used to simulate the temporal variation of PBDE concentrations in Zhelin Bay. Modeled short-term trends showed a relatively swift transport of PBDE congeners in the water column to the atmosphere and sediments. Over the long term, sediment concentrations gradually decreased, in contrast to the less rapid declines observed in the atmosphere and water. Furthermore, this study revealed that the transport and transformation processes of PBDEs in the Zhelin Bay environment were considerably influenced by the diffusion coefficient in water, the water-side mass transfer coefficient at the water-sediment interface, the sediment resuspension rate, and the organic carbon-water partition coefficient.

Spatial distribution, source, and ecological risk of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in Jiaozhou Bay, China

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) are commonly found in the environment as components of brominated flame retardants. Due to their potential impact on human health and wildlife, it is imperative to closely monitor and manage their levels in the environment. This study investigated the spatial distribution, sources, and ecological risks of PBDEs and HBCDs in Jiaozhou Bay (JZB), a large bay situated on the eastern coast of China. The results showed that PBDE concentrations ranged from not detected (ND) to 7.93 ng/L in the water and ND to 65.76 ng/g in the sediment, while HBCD concentrations ranged from ND to 0.31 ng/L in the water and ND to 16.63 ng/g in the sediment. Furthermore, we observed significantly higher concentrations of PBDEs and HBCDs in the inner JZB compared to the outer JZB. Our source apportionment analysis showed that PBDEs primarily originated from the production and debromination of BDE-209, as well as the emission of commercial PeBDEs, whereas HBCDs in sediments mostly stemmed from anthropogenic activities and river input. Finally, our eco-logical risk assessment highlighted the need for continuous monitoring of PBDEs in JZB sediments. Overall, our study aims to provide valuable assistance for the environmental management of the JZB bay area, which is characterized by a complex net-work of rivers and a thriving economy.

Distribution, sources and dispersion of polybrominated diphenyl ethers in the water column of the Strait of Georgia, British Columbia, Canada

Dissolved and particulate polybrominated diphenyl ether (PBDE) concentrations were measured in the water column of the Strait of Georgia (SoG), Haro Strait, Juan de Fuca Strait, Burrard Inlet, and the Fraser River to assess their sources and dispersion. Total PBDE concentrations in the water column of the southern basin of the SoG are surprisingly high (similar to the load reported for coastal zones heavily impacted by human activities). Moreover, the dissolved fraction (i.e. passing through a 2.2 μm pore size filter) accounts for >95 % of the total load, which is unlike what is more typically found in other coastal zones, where particulate PBDEs generally dominate. Decreasing concentrations away from the southern SoG, eventually reaching typical open ocean values in Juan de Fuca Strait, point to the Vancouver metropolitan area as the main proximal source of PBDEs. About half of the direct PBDE input comes from wastewater treatment plants, with atmospheric deposition and the Fraser river accounting for most of the rest. However, these direct sources alone cannot explain the high dissolved PBDE load observed in the water column of southern SoG. PBDE scavenging rates estimated from concentration gradients and water transit times imply a PBDE flux to the seafloor which largely exceeds the measured burial rates of PBDEs in sediments. To reconcile these observations and explain the dominance of the dissolved fraction in the water column of the southern SoG, we invoke and provide supporting evidence for the release of colloidal PBDE from the resuspension of PBDE-contaminated sediments by bottom currents. If confirmed, this continued PBDE exchange between sediments and the water column would maintain high levels of PBDEs, and possibly other hydrophobic and persistent organic contaminants, in the water column of the southern SoG until the contaminated sediments are buried below the sediment mixed layer.

Polybrominated diphenyl ethers in water, suspended particulate matter, and sediment of reservoirs and their tributaries in Shenzhen, a mega city in South China

Urban reservoirs serve many purposes including recreation and drinking water, and larger bodies of water can alter the surrounding air temperatures, making urban areas cooler in summer and warmer in winter. However, reservoirs may also be sinks for contaminants. One such group of contaminants, the polybrominated diphenyl ethers (PBDEs), are persistent organic pollutants known to accumulate in sediments and suspended particulate matter (SPM). Few studies have been conducted on PBDEs in water, SPM, and sediment from reservoirs of Shenzhen which is a mega city in South China. To this end, 12 PBDEs were measured in water, SPM, and sediment samples during the dry season (DS) and wet season (WS), to explain the spatiotemporal distribution, congener profiles, sources, and risks of pollutants in four reservoirs (A-D) and their tributaries in the study region. The concentration of ∑₁₂PBDEs during the DS was found to be significantly higher than that during the WS. Source apportionment suggested that commercial penta-, octa-, and deca-BDEs are the major components of PBDEs, resulting mainly from atmospheric deposition, wastewater discharge, and external water-diversion projects. Further, attention should be paid to electronic equipment manufacturing factories in the study area. Risk assessment indicated risk of PBDEs (especially BDE-209) in sediment and SPM to be of concern. This study provides important data support for the control of PBDEs in natural drinking water sources.

Insight into the photodegradation and universal interactive products of 2,2',4,4'-tetrabromodiphenyl ether on three microplastics

The transformation process of contaminants on microplastics (MPs) exposed to sunlight has attracted increasing attention. However, the interactions between them are typically disregarded; therefore, this work investigated the photodegradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on three MPs (polystyrene (PS), polypropylene (PP) and polyethylene (PE)) and the interactions between these two. The inhibition of aged PS on the elimination of BDE-47 was due to light shielding, while aged PP and PE increased the degradation rate. More hydroxyl radicals (HO•) was detected in the PS system, which resulted in the higher degradation rate of BDE-47 on PS. A total of 33 different products were identified and four reaction pathways were presented, and the reaction mechanisms mainly included debromination, hydroxylation, carbon-oxygen-bond breaking and interactive reactions. The Ecological Structure Activity Relationship (ECOSAR) and Toxicity Estimation Software Tool (TEST) programs were used to evaluate the toxicity of reaction products, and the results indicated that even though BDE-47 was the most toxic, the interaction products were still toxic or harmful to aquatic organisms. This study provides significant information on the photodegradation of contaminants on common microplastics and their interaction, which cannot be ignored.

Semi-enclosed bays serve as hotspots for black carbon burial: A case study in Jiaozhou Bay, western Yellow Sea

The provenance of black carbon (BC) and its role in affecting contaminant cycling in both the atmosphere and aquatic environments have been extensively studied. However, the fate and cycling dynamics of BC, particularly in marine environments, are poorly understood. Herein, soot BC was determined in the semi-enclosed Jiaozhou Bay to examine the seasonal variability, residence timescale in seawater, and settling flux to sediments, together with particle-reactive ²³⁴Th. Soot BC ranged from 0.39 to 4.26 μmol-C L^-1. On average, spring produced the highest value of 1.88 ± 0.31 μmol-C L^-1, followed by winter (1.59 ± 0.18 μmol-C L^-1), summer (0.94 ± 0.09 μmol-C L^-1), and autumn (0.90 ± 0.09 μmol-C L^-1). The seasonality of soot BC was similar to the activity concentration of particulate ²³⁴Th (i.e., ²³⁴Th_P). The close relationships between soot BC and ²³⁴Th_P (p < 0.01) provide the basis for the application of ²³⁴Th to trace the fate of soot BC. Based on the ²³⁴Th deficit with respect to ²³⁸U, the residence times of soot BC were estimated to be 41 ± 6 d and 36 ± 5 d for May-August and August-November, respectively. The shorter residence times of soot BC than that of seawater indicated that soot BC delivered to Jiaozhou Bay settled in the local sediments. Furthermore, soot BC concentrations were higher in the inflow seawater from the Yellow Sea than the outflow water from Jiaozhou Bay, implying a net input of soot BC from the Yellow Sea to Jiaozhou Bay. The soot BC fluxes were 0.266 ± 0.035 mmol-C m^-2 d^-1 and 0.0472 ± 0.0065 mmol-C m^-2 d^-1 for May-August and August-November, respectively. From the bay-scale perspective, Jiaozhou Bay had buried 0.101 ± 0.010 Gg of soot BC each year. These results indicate that the semi-enclosed Jiaozhou Bay acts as an effective trap for soot BC and particle-reactive contaminants.

Transport and dilution of fluvial antibiotic in the Upper Gulf of Thailand

A three-dimensional hydrodynamic-antibiotic model is developed to investigate the transport and dilution of sulfamethoxazole (SMX) in the Upper Gulf of Thailand (UGoT). The simulation produced a spatially averaged annual mean SMX concentration of 0.58 μgm^-3, which varied slightly between seasons assuming a temporally constant river SMX loading observed in August. In contrast, the horizontal distribution of SMX concentrations strongly varied with season because of the changing residual currents. In addition, SMX is diluted to concentrations lower than 10% of those in river waters a short distance offshore of the estuaries. To better understand this behavior, we examined the relationship between salinity and SMX concentrations in the UGoT. The annual budget demonstrates that 98% of SMX in the UGoT is removed by natural decomposition. As the concentrations of fluvial pollutants in the UGoT depend on their river loading and decomposition rates, functions were derived to predict pollutant concentrations and flushing times based on the river input flux and half-life.

Metabolic process and spatial partition dynamics of Atrazine in an estuary-to-bay system, Jiaozhou bay

The spatial distributions of atrazine and six types of metabolites in water, suspended particulate sediment (SPS), and surface sediment in an estuary-to-bay system were analyzed. The water distance of metabolites demonstrated that degradation was more active in coastal zone and the Desisopropylatrazine had the shortest half-distance of 1.6 Km from the river mouth. The dechlorination-hydroxylation metabolites were the dominant pollutants in the bay and the Didealkyl-atrazine (DDA), Deisopropylhydroxy-atrazine (DIHA), and Deethylhydroxy-atrazine (DEHA) had higher concentrations in all three mediums. The DDA had the biggest content (6.58 ng/g) in the coastal sediment. The DIHA was the only pollutant had bigger concentration during the transport, and the others continually degraded with smaller value. The spatial distributions of pollutants in sediment had different patterns in water with SPS. The water-particle phase partition coefficient (K_p) analysis indicated that the partition process was more active in the estuary than the bay, and the metabolites had stronger capacity than atrazine. The correlations between K_p with octanol-water partitioning coefficient showed their physic-chemical properties were the important factors for vertical partition between seawater with sediment. The correlations with marine environmental factors demonstrated that the metabolite type was the direct factor for the redistributions during the transport.

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.

Ecotoxico Linking of Phthalates and Flame-Retardant Combustion Byproducts with Coral Solar Bleaching

Persian Gulf coral reefs are unique biota communities in the global sunbelts in being able to survive in multiple stressful fields during summertime (>36 °C). Despite the high-growth emerging health-hazard microplastic additive type of contaminants, its biological interactions with coral-algal symbiosis and/or its synergistic effects linked to solar-bleaching events remain unknown. This study investigated the bioaccumulation patterns of polybrominated diphenyl ether (PBDE) and phthalate ester (PAE) pollutants in six genera of living/bleached corals in Larak Island, Persian Gulf, and their ambient abiotic matrixes. Results showed that the levels of ∑₁₈PBDEs and ∑₁₃PAEs in abiotic matrixes followed the order of SPMs > surface sediments > seawater, and the cnidarian POP-uptake patterns (soft corals > hard corals) were as follows: coral mucus (138.49 ± 59.98 and 71.57 ± 47.39 ng g^-1 dw) > zooxanthellae (82.05 ± 28.27 and 20.14 ± 12.65 ng g^-1 dw) ≥ coral tissue (66.26 ± 21.42 and 34.97 ± 26.10 ng g^-1 dw) > bleached corals (45.19 ± 8.73 and 13.83 ± 7.05 ng g^-1 dw) > coral skeleton (35.66 ± 9.58 and 6.47 ± 6.47 ng g^-1 dw, respectively). Overall, findings suggest that mucus checking is a key^/facile diagnostic approach for fast detection of POP bioaccumulation (PB) in tropical corals. Although studied corals exhibited no consensus concerning hazardous levels of PB (log BSAF < 3.7), our bleaching evidence showed soft corals as the ultimate "summer winners" due to their flexibility/recovering ability.

Feeding behavior toxicity in the marine rotifer Brachionus plicatilis caused by 2,2',4,4'-tetrabromodiphenyl ether (BDE-47): Characteristics and mechanisms

Polybrominated diphenyl ether contamination in marine environments has received special attention due to its accumulation and magnification in the marine food web and toxicity to organisms. In the present study, a series of short-term toxicological tests were conducted with the marine rotifer Brachionus plicatilis to assess the effects on ingestion and digestive performance after treatment with 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) at nonlethal concentrations under controlled laboratory conditions and to analyze the possible mechanism. The results showed that with accumulation in rotifers, BDE-47 caused a significant decline in the filtration and feeding rates in a concentration-dependent manner. Moreover, the activities of amylase (AMS) and protease were affected, indicating that BDE-47 impaired ingestion and digestion efficiency. BDE-47 exposure did not lead to abnormal microstructures in the main digestive tract (e.g., cilia around the corona, mastax, stomach, digestive gland and esophagus), but the gastric parietal cells shrank, suggesting nutritional deficiency. BDE-47 prominently induced the occurrence of irregular mitochondria at the cilia root, and mitochondrial and isocitrate dehydrogenase activity declined, indicating mitochondrial dysfunction. Furthermore, the activity of ATPase, which catalyzes ATP hydrolysis, decreased as the BDE-47 concentration rose, implying that BDE-47 retarded rotifer ATP dynamics, inevitably interfering with cilia movement to ingest food. Additionally, a significant decline in acetylcholine esterase activity was observed, which led to a hindrance in neurotransmission involved in food intake and digestion. Altogether, our results demonstrated that nonlethal concentrations of BDE-47 could induce feeding depression in rotifers, which is mainly attributed to stymied energy metabolism and nerve conduction.

Depicting an energetic chain involved in physiological responses of blue mussel Mytilus edulis coping with BDE-47 exposure

Depiction on an energetic chain in terms of assimilation, allocation and consumption as well as the linkage between energetic alteration and physiological process was performed in blue mussel Mytilus edulis coping with tetrabromodiphenyl ether (BDE-47) based on a 21-day bioassay to shed light on the possible mechanism from energetic perspective. The filtration was hindered along with BDE-47 concentration increment and the influence of digestion was suggested according to the combination of the digestive enzymatic activities' alteration and digestive gland tissue impairment, both of which decided the energy availability reduction. Energy consumption indicated by the electron transport system activity was firstly inhibited while was greatly increased with BDE-47 increment, and the cellular energy allocation and adenylate pool were decreased simultaneously. An energetic chain was thus depicted: it tended to reduce energy absorption, elevate the energy consumption and decrease the energy metabolism with BDE-47 exposure, and M. edulis adopted the energetic strategy with variation regarding to the stressing level, suggesting as the preference switched from protein utilization to lipid utilization with the concentration increment. A consistence was observed in index of growth and survival with the change of energy allocation, inferring the energetic involvement in sustaining the viability of the mussel.

Polybrominated diphenyl ethers in surface sediments from fishing ports along the coast of Bohai Sea, China

The distribution, congener patterns, possible sources, and ecological risks of polybrominated diphenyl ethers (PBDEs) were investigated in the surface sediments of 20 fishing ports along the coast of Bohai Sea. PBDEs are widespread pollutants in fishing ports, and the total concentrations of 14 PBDEs (∑₁₄PBDEs) are 4.23-20.59 ng/g with a mean value of 12.56 ng/g. BDE-209 was the dominant congener. The fishing ports with high PBDE concentrations were located near Liaohe River, Haihe River, manufacturing plants of BFRs near Laizhou Bay, and tipping areas of marine garbage. BDE-209 and BDE-47 were the most important congeners that discriminate PBDE pollution. The possible sources of PBDEs included the input of commercial mixtures of penta-BDE, octa-BDE, and deca-BDE, the debromination of BDE-209, and the atmospheric transport of the low brominated diphenyl ethers. The ecological risks in surface sediments were attributed to the congeners of tetra-BDE, penta-BDE, and deca-BDE with low or medium levels.

A comparison of developmental toxicity of brominated and halogen-free flame retardant on zebrafish

Brominated diphenyl ethers (BDEs) are halogenated flame retardants. Several concerns related to persistence and toxicity of BDEs have been resulted in a growing need of BDEs replacement. The use of halogen-free flame retardants (HFFR) has increased as a safer alternative, but little information is available on their toxic potential for environmental health and for developing organisms. Therefore, the aim of this study was to evaluate and compare the toxicity of three congeners of BDEs (BDE-47, BDE-99 and BDE-154) with an HFFR (aluminum diethylphosphinate, ALPI) on zebrafish (Danio rerio) by assessing endpoints of lethality, sub-lethality and teratogenicity at the earlier stages of development. The highest tested concentration of BDE-47 (12.1 mg/L) induced pericardium and yolk sac edemas that first appeared at 48 h post-fertilization (hpf) and then were mostly reabsorbed until 144 hpf. BDE-47 also showed a slight but non-significant tendency to affect swim bladder inflation. The rate of edemas increased in a concentration-dependent manner after exposure to BDE-99, but there were no significant differences. In addition, the congener BDE-99 also presented a slight and non-significant effect on swim bladder inflation, but only at the highest concentration tested. Regarding BDE-154 exposure, the rate of edemas and swim bladder inflation were not affected. Finally, in all ALPI exposure concentrations (0.003 up to 30 mg/L), no sub-lethal or teratogenic effects were observed on developing organisms until 96 hpf. Although further studies are needed, our results demonstrate that when comparing the developmental toxicity induced by flame retardants in zebrafish, the HFFR ALPI may be considered a more suitable alternative to BDE-47.

Legacy and novel halogenated flame retardants in seawater and atmosphere of the Bohai Sea: Spatial trends, seasonal variations, and influencing factors

Seventeen halogenated flame retardants (HFRs) were concurrently analyzed in surface seawater and low atmospheric samples from the Bohai Sea during four research cruises. HFRs mainly existed in particulate phases, and in general decabromodiphenyl ethane (DBDPE) was the predominant compound in both air and water samples. Relatively high concentrations were observed in the water of Laizhou Bay (LB), where the largest manufacturing base of brominated flame retardants (BFRs) in China is located and weak water exchange occurs. Transport from LB by coastal currents may be the main source of BFRs in some areas without emission sources. The HFRs in seawater exhibited distinct seasonal variation, with significantly higher concentrations in winter than those in summer. The controlling factors include the resuspension of sediment induced by large wind waves in winter and phytoplankton scavenging in spring and seawater stratification in summer. HFRs composition varied largely in different seasons, due to the different extents of riverine input and atmospheric deposition. Normally, for air masses passing through the nearby industrial regions, high concentrations of DBDPE (up to 1780 pg m^-3) co-existed with high total suspended particle (TSP) levels (up to 150 μg m^-3). The estimated atmospheric deposition fluxes of HFRs were 19, 51, and 80 kg season^-1 in spring, summer, and winter, respectively, indicating that the Bohai Sea is a sink of HFRs via atmospheric deposition. This study has increased our understanding of the behaviors and fates of the legacy and novel HFRs in the shallow coastal sea.

Evaluation of the toxic response induced by BDE-47 in a marine alga, Phaeodactylum tricornutum, based on photosynthesis-related parameters

The pollution of polybrominated diphenyl ethers (PBDEs) is becoming a pressing environmental problem in aquatic environments, and its threat to aquatic organism has received much attention. In this study, Phaeodactylum tricornutum was treated with 0.8 and 4 mg L^-1 2,2',4,4'-tetrabrominated biphenyl ether (BDE-47), the most toxic PBDEs, for 96 h. BDE-47 inhibited cell growth in a time- and concentration-dependent manner. Observation of cell ultrastructure suggested the damage of the chloroplasts morphology. BDE-47 also decreased the chlorophyll content and the oxygen evolution rate, and altered the performance of photosystems. Transcriptomic analysis revealed differential expression of 62 genes related to photosynthesis in BDE-47 treatments (4 mg L^-1) and transcription suppression of 58 genes involved in chlorophyll synthesis, antenna proteins, oxygen evolution, electron transport and downstream carbon fixation, implying potential toxicity targets in cells. Additionally, the levels of reactive oxygen species (ROS) and lipid peroxidation increased under BDE-47 stress and were positively correlated with photosynthesis inhibition. Pretreatment with the ROS scavenger N-acetyl-l-cysteine reduced the extent of inhibition, suggesting that ROS was responsible for these effects. Another experiment with the electron transport chain inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea showed that the generation of ROS was partially blocked, primarily indicating that photosynthetic inhibition induced by BDE-47 contributed to ROS overproduction. Thus, BDE-47 inhibited the photosynthesis by down-regulating the gene expression. This change stimulated ROS production, further leading to chloroplast membrane damage to aggravate this inhibition via a feedback loop. These effects of BDE-47 had adverse outcomes on the entire physiological state and the population growth of the microalgae.

First report on polybrominated diphenyl ethers in the Iranian Coral Islands: Concentrations, profiles, source apportionment, and ecological risk assessment

Coral reefs are challenged by multiple stressors due to the growing industrialization. Despite that, data on their environment are still scarce, and no research is yet performed on polybrominated diphenyl ethers in the Persian Gulf area. Seeking to fill in this gap, the present study aims to determine spatio-vertical distributions, source apportionment and ecological risk of polybrominated diphenyl ethers in the sediment cores and seawater samples from ten coral reef Islands in the Persian Gulf, Iran. Σ₁₂PBDEs concentrations ranged from 0.42 ± 0.04 to 47.14 ± 1.35 ng g^-1 dw in sediments, and from 1.17 ± 0.06 to 7.21 ± 1.13 ng L^-1 in seawater. The vertical polybrominated diphenyl ethers distribution varied significantly among the sampling stations and different depths with a decreasing trend towards the surface and peaks around 12-20 cm. Both in the seawater and sediment samples, elevated polybrominated diphenyl ethers loadings were observed in highly industrialized areas. Deca-bromodiphenyl ether-209 was the predominant congener along the sediment cores, whereas Tetra-bromodiphenyl ether-47 and Penta-bromodiphenyl ether-100 dominated in seawater samples. Commercial Deca-bromodiphenyl ether mixture was found to be the major source of polybrominated diphenyl ethers. Penta-bromodiphenyl ether was revealed to be the major ecological risk driver in the study area: it posed medium to high-risk quotient to sediment dwelling organisms. This study indicated that coral reefs are playing an important role in retaining polybrominated diphenyl ethers and highlighted the need to manage polybrominated diphenyl ethers contamination in the coral reef environment.

Knowledge gaps in ecotoxicology studies of marine environments in Pacific Island Countries and Territories - A systematic review

The Pacific Island Countries and Territories (PICTs) are heavily dependent on the marine resources for food security, employment, government revenue and economic development, hence the concern about the potential exposure of these resources to pollutants. The main goal of this review was to identify ecotoxicology studies published that were done in PICTs. Four major gaps were identified: i) a quantitative gap, with low number of studies published on the PICTs; ii) a geographic gap, where ecotoxicology studies have unevenly covered the different PICTs; iii) a temporal gap, as no biological effect monitoring study has so far been published for the PICTs; and, iv) a pollutants gap, as all of the PICTs studies focused mainly on environmental monitoring studying on average two types of pollutants (heavy metals and pesticides) per PICT only. We suggest, therefore, the potential risk to the marine environment to be estimated by assessing the fate of pollutants via chemical and biological effect monitoring.

The toxicity, bioaccumulation and debromination of BDE-47 and BDE-209 in Chlorella sp. under multiple exposure modes

Polybrominated diphenyl ethers (PBDEs) are a series of important persistent organic pollutants (POPs) in marine environments. Microalgae are the start of PBDEs bioaccumulated and bioconcentrated along the marine food web. In order to investigate the variations of PBDEs bioaccumulation by microalgae and its influencing factors, we set up a series of experiments with Chlorella sp. under different BDE-47 or BDE-209 exposure modes to measure their toxicity, bioaccumulation and degradation patterns. The inhibition effect on cell growth was much more obvious in BDE-47 than BDE-209, with the EC₅₀ values at 96 h calculated as 64.7 μg L^-1 and 4070 μg L^-1, respectively. Microalgal uptake rates showed BDE-209 diffused less into cells than BDE-47, with highest measured uptake rates of 0.145 × 10^-7 μg h^-1 cell^-1 and 0.45 × 10^-7 μg h^-1 cell^-1, respectively. The bioaccumulation amount by unit microalgal cell varied with PBDE concentrations and culture time, which appeared to be related to the changes of extracellular polymeric substances (EPS) and cellular neutral lipids under the toxicity of PBDEs. Finally, we found Chlorella sp. delayed the debromination patterns of BDE-209 compared to seawater. This study linked the toxicity, microalgal bioaccumulation and metabolism of PBDEs, provided new insights in the research of POPs by microalgae and marine food webs.

Singlet Oxygen Photogeneration in Coastal Seawater: Prospect of Large-Scale Modeling in Seawater Surface and Its Environmental Significance

Chromophoric-dissolved organic matter (CDOM) acts as the precursor to singlet oxygen (¹O₂) in natural waters, while water acts as the main scavenger. In this study, we showed that ¹O₂ in coastal seawater can be successfully predicted from CDOM parameters. The ¹O₂ steady-state concentration [¹O₂]_ss and photoformation rate (R¹O₂) varied by a factor of 6 across 13 sampling stations in the Seto Inland Sea, Japan, ranging from 1.2 to 8.2 × 10^-14 M and 3.32 to 22.7 × 10^-9 M s^-1, respectively. Investigation of CDOM optical properties revealed that CDOM abundance measured as the absorption coefficient at 300 nm (a₃₀₀) had the strongest correlation (r = 0.96, p < 0.001) with [¹O₂]_ss, while parameters indicative of CDOM quality (e.g., spectral slope) did not influence [¹O₂]_ss. A linear relationship between [¹O₂]_ss and a₃₀₀, normalized to a sunlight intensity of 0.91 kW/m², was derived as [¹O₂]_ss (10^-14 M) = 2.12(a₃₀₀) + 0.48. This was then used to predict [¹O₂]_ss using a₃₀₀ values from a subsequent, independent sampling exercise conducted 2 years after the first sampling. There was a good agreement (r = 0.93, p < 0.001) between the predicted values and the experimentally determined values based on a 95% prediction interval plot. Kinetic estimations using [¹O₂]_ss suggest that ¹O₂ mediates the degradation of tetrabromobisphenol A in surface seawater (t_1/2 = 0.63 days) while also contributing to the indirect photolysis of methyl mercury. The findings from this study suggest that large-scale modeling of ¹O₂ generation in surface seawater from CDOM parameters is possible with useful environmental significance for determining the fate of pollutants.

Spatiotemporal distribution, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the urbanized semi-enclosed Jiaozhou Bay, China

Coastal contamination by polycyclic aromatic hydrocarbons (PAHs) is a worldwide issue. Nevertheless, the spatiotemporal distribution of PAHs in the urbanized semi-enclosed bays in China remains relatively uncharacterized. Here we present measurements of 15 priority PAHs in the water and sediment of the Jiaozhou Bay, as well the assessment of their spatiotemporal distribution, sources and ecological risk. The total PAH (ΣPAH) concentrations ranged from 23.6 to 86.2 ng L ^-1 in the water and from 37.7 to 290.9 ng g^-1 in the sediment. The average ΣPAH concentration in the water was significantly higher in the winter (52.8 ng L ^-1) than in the spring (30.4 ng L ^-1) (α = 0.05 level). Average concentration of phenanthrene in the water was 8.9 ng L^-1 in the spring and 15.7 ng L^-1 in the winter and the highest of PAHs, contributing about 29.4% to ΣPAHs. Compared with three-ring PAHs, four- and five-ring PAHs were more tended to accumulate in the sediment, and the partitioning into sediment was influenced by the water salinity. The spatial distribution of ΣPAH concentrations in the water were controlled by water exchange capability. Organic matter content and sediment texture played important roles in determining the spatial distribution of ΣPAHs in the sediment. Molecular diagnostic ratio analysis indicated that pyrogenic source was the main source for PAHs in the Bay. Specifically, the positive matrix factorization (PMF) model indicated that vehicle emission, biomass combustion, coal combustion, and petrogenic sources contributed for 41.6, 20.2, 20, and 18.2% of ΣPAHs, respectively. The risk assessment by sediment quality guidelines suggested that adverse biological effects are expected to occur rarely in the sediment.

Polystyrene microplastics increase uptake, elimination and cytotoxicity of decabromodiphenyl ether (BDE-209) in the marine scallop Chlamys farreri

Microplastics are a growing problem in marine environments due to their ubiquitous occurrence and affinity for chemical pollutants. However, the influence of microplastics on the uptake, depuration and toxicity of decabromodiphenyl ether (BDE-209) in marine organisms is unclear. We exposed the marine scallop Chlamys farreri to polystyrene microplastics (PS; 125 μg/L) combined with BDE-209 (10 and 100 μg/L) to determine their toxicokinetics, cellular toxicity and histopathological effects. The results showed that PS acted as both a carrier and a scavenger for the bioaccumulation of BDE-209. Importantly, the carrier role of PS was greater than scavenger one. PS increased the negative effect of BDE-209 (100 μg/L) on hemocyte phagocytosis, and ultrastructural changes in gills and digestive gland of scallops due to their carrier role for the bioaccumulation of BDE-209. However, PS did not increase the DNA damage of BDE-209 on the hemocytes. These findings are evidence of microplastics transferring adsorbed pollutants to marine organisms, and increasing their toxicity.

Polybrominated diphenyl ethers in the environment and human external and internal exposure in China: A review

Polybrominated diphenyl ethers (PBDEs) are widely used as brominated flame retardants. Because of their toxicity and persistence, some PBDEs were restricted under the Stockholm Convention in 2009. Since then, many studies have been carried out on PBDEs in China and in many other countries. In the present review, the occurrences and contamination of PBDEs in air, water, sediment, soil, biota and daily food, human blood, hair, and other human tissues in China are comprehensively reviewed and described. The human exposure pathways and associated health risks of PBDEs are summarized. The data showed no obvious differences between North and South China, but concentrations from West China were generally lower than in East China, which can be mainly attributed to the production and widespread use of PBDEs in eastern regions. High levels of PBDEs were generally observed in the PBDE production facilities (e.g., Jiangsu Province and Shandong Province, East China) and e-waste recycling sites (Taizhou City, Zhejiang Province, East China, and Guiyu City and Qingyuan City, both located in Guangdong Province, South China) and large cities, whereas low levels were detected in rural and less-developed areas, especially in remote regions such as the Tibetan Plateau. Deca-BDE is generally the major congener. Existing problems for PBDE investigations in China are revealed, and further studies are also discussed and anticipated. In particular, non-invasive matrices such as hair should be more thoroughly studied; more accurate estimations of human exposure and health risks should be performed, such as adding bioaccessibility or bioavailability to human exposure assessments; and the degradation products and metabolites of PBDEs in human bodies should receive more attention. More investigations should be carried out to evaluate the quantitative relationships between internal and external exposure so as to provide a scientific basis for ensuring human health.

Spatial Distribution and Congener Profiles of Polybrominated Diphenyl Ethers in Surface Sediment from Sanmen Bay and Xiamen Bay, Southeast China

Coastal areas are influenced by anthropogenic input of a variety of organic pollutants, among which polybrominated diphenyl ethers (PBDEs) represent an important group. In the present study, we investigated the contamination status of PBDEs in surface sediment from two economically important Bays in Southeast China, Sanmen Bay (SMB; n = 29) and Xiamen Bay (XMB; n = 10). Concentrations of ∑PBDEs ranged from 2.2 to 78.5 ng/g dw (median 5.7 ng/g dw) in SMB and 7.9-276.0 ng/g dw (median 43.5 ng/g dw) in XMB, respectively. A nearshore-offshore decreasing trend was observed for both ∑PBDEs and BDE-209 concentrations, indicating strong urban influences. Although the current levels would not produce any significant impact on benthos and aquatic ecosystems of the studied regions, continuous monitoring is needed to understand the temporal trends of contamination in the important coastal waters and whether sediment-associated PBDEs constitute a potential source to aquatic ecosystems.

Sorption of polybrominated diphenyl ethers by microplastics

The sorption of polybrominated diphenyl ethers (PBDEs) onto polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA) microplastics was analyzed using different kinetic and isotherm models, and under various environmental conditions, including temperature, pH, salinity and dissolved organic matter (DOM). The sorption capacity was in the order of PS > PA > PP > PE, due to the different crystallinity, specific surface area, and surface structure. PS demonstrated the equilibrium sorption capacity, namely, 6.41 ng/g BDE-47, 12.83 ng/g BDE-99, and 14.42 ng/g BDE-153. The second-order kinetic model described the sorption kinetics of PBDEs, and surface sorption was the main mechanism. The sorption of PBDEs by microplastics was a multilayer and physical process. Low temperatures reduced BDE-47 sorption on microplastics, and sorption was a spontaneous and endothermic process. The sorption of BDE-47 was not significantly influenced by pH and salinity. However, DOM exerted a negative effect on the sorption of BDE-47.

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.

Spatiotemporal distribution, source apportionment and ecological risk assessment of PBDEs and PAHs in the Guanlan River from rapidly urbanizing areas of Shenzhen, China

In this study, nine congeners of polybrominated diphenyl ethers (PBDEs) and sixteen congeners of polycyclic aromatic hydrocarbons (PAHs) were measured in water samples to elucidate their spatial distribution, congener profiles, sources and ecological risks in the Guanlan River during both the dry season (DS) and the wet season (WS). The concentration of Σ₉PBDE ranged from 58.40 to 186.35 ng/L with an average of 115.72 ng/L in the DS, and from 8.20 to 37.80 ng/L with an average of 22.15 ng/L in the WS. Meanwhile, the concentration of Σ₁₆PAHs was ranged from 121.80 to 8371.70 ng/L with an average of 3271.18 ng/L in the DS and from 1.85 to 7124.25 ng/L with an average of 908.11 ng/L in the WS. The concentrations of PBDEs and PAHs in the DS were significantly higher than those in the WS, probably due to the dilution of the river during the rainy season. Moreover, the spatial distribution of pollutants revealed decreasing trend in the concentration from upstream to downstream and almost identical pattern was observed during both seasons. The source apportionment suggested that penta-BDE and to some extent octa-BDE commercial products were major sources of PBDEs in the study area. However, the sources of PAHs were mainly comprised of fossil fuels and biomass burning, followed by the petroleum products and their mixtures. The results of the ecological risk assessment indicated PBDEs contamination posed high ecological risks, while PAHs exhibited low or no ecological risks in the study area. Consistent with the environmental levels, the ecological risks of pollutants were relatively lower in the WS, compared to that in the DS. The results from this study would provide valuable baseline data and technical support for policy makers to protect the ecological environment of the Guanlan River.

The toxic mechanisms of BDE-47 to the marine diatom Thalassiosira pseudonana-a study based on multiple physiological processes

Polybrominated diphenyl ethers (PBDEs), a series of highly persistent organic pollutants (POPs), are ubiquitous in marine ecosystems. As key primary producers, microalgae are of great importance on evaluating the environmental outcome of PBDEs pollution. In this study, the toxic mechanisms of BDE-47 on the marine diatom Thalassiosira pseudonana were evaluated by measuring multiple physiological processes. Three concentrations of BDE-47 (25, 15 and 5 μg L^-1) were used along with two controls (blank: no BDE-47 or DMSO; negative control: only DMSO). Experiments lasted 144 h (6 days), in which the actual BDE-47 concentrations, cell densities, nutrient (nitrate and phosphate) uptake, pigment compositions, photosynthetic physiology, cell morphology and cellular contents (organic carbon and nitrogen) were measured at 12-48 h intervals. The toxic mechanisms of BDE-47 on T. pseudonana cells were evaluated by measuring multiple physiological processes including photosynthesis, nutrient uptake, cellular material synthesis and cell cycle progressions. The cell divisions of T. pseudonana were severely inhibited by the stress of BDE-47, but the photosynthetic parameters were much less declined and recovered earlier than the cell divisions in the same BDE-47 treatments. The unsuppressed uptake rates of nutrients, increased cell volume and cellular contents indicated the cellular material synthesis proceeded normally. Finally, we found that the cell cycle was arrested in G2/M phase under the stress of BDE-47, we thus concluded that the inhibition of cell divisions by BDE-47 was not due to the lack of energy or cellular materials, where the cell cycle arrest happened; this might be the most important toxicological outcome.

A simulation of the seasonal variation of decabromodiphenyl ether in a bay adjacent to the Yellow Sea

A three-dimensional transport-ecosystem-POP coupled model is configured to simulate the seasonal variation and budget of decabromodiphenyl ether (BDE-209) in a semi-enclosed bay adjacent to the Yellow Sea. The model includes five types of BDE-209 (gaseous, dissolved, phytoplankton-bound, detritus-bound, and suspended particulate matter (SPM)-bound) and related physical and biogeochemical processes, such as advection and diffusion due to seawater motion, input from rivers, air-sea exchange, decomposition of dissolved BDE-209, uptake and depuration between dissolved and phytoplankton-bound BDE-209, mortality of phytoplankton-bound BDE-209, remineralization and sinking of detritus-bound BDE-209, and sinking of SPM-bound BDE-209. Model results show that the dissolved and particulate BDE-209 in the bay are higher in the nearshore area than in offshore area and are higher in summer than in other seasons; these results are consistent with field data. SPM-bound BDE-209 is dominant among the five types due to its large supplying from rivers. Dissolved BDE-209 concentrations are around 5-fold that of phytoplankton-bound BDE-209, which depends on uptake and depuration rate constants between dissolved and phytoplankton-bound BDE-209 and biomass of phytoplankton. Evaluation of mass balance indicates that the input from rivers is major source of BDE-209, while the exchange with the Yellow Sea is major sink. Sensitivity experiments demonstrate that the input of BDE-209 from rivers plays the most significant role in the seasonal variation of dissolved and particulate BDE-209 concentrations, and the change in water temperature is a secondary factor.

Effects of surfactant on the degradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by nanoscale Ag/Fe particles: Kinetics, mechanisms and intermediates

Surfactants are known to enhance the degradation of halogenated organics by nanoscale zerovalent iron (n-ZVI) or n-ZVI-based bimetallic particles, but the mechanism of the promotion is not well understood. In this study, we used nanoscale Ag/Fe particles (n-Ag/Fe) to degrade 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in different surfactant solutions. The results show that the nonionic surfactant TX-100 had the best promoting effect, which might be attributed to the decrease in particle agglomeration and improvement of mass transfer efficiency after the adsorption of TX-100 on n-Ag/Fe. The distribution analysis of BDE-47 in solid and liquid phases indicates that when the concentration of TX-100 in aqueous solution was above critical micelle concentration, BDE-47 started to dissolve in the liquid phase. Thus, TX-100 micelles can enhance the mass transfer efficiency of BDE-47. However, a too high concentration of TX-100 (above 1.0 mM) would influence the promotion effect of BDE-47 degration, which might be attributed to the excessive and thicker micelles of TX-100 hindering the contact between BDE-47 and n-Ag/Fe. We also studied the degradation pathway of BDE-47 and its products, and found that surfactants did not change the degradation pathway of BDE-47.

Spatio-temporal variability, distribution and sources of n-alkanes and polycyclic aromatic hydrocarbons in reef surface sediments of Kharg and Lark coral reefs, Persian Gulf, Iran

Environmental pollution, particularly oil pollution, has been a long-standing problem in marine areas. With the aim to assess the pollution status in the Persian Gulf, Iran, herein surface sediments were collected from Kharg and Lark coral reefs, in summer (dry season) and winter (wet season), to evaluate the spatio-temporal variations of n-alkanes and PAHs. The mean total organic carbon (TOC⁾ contents of sediments showed a significantly dramatic variation (p < 0.05) in both seasons at both Islands, with high values recorded at sites located near pollutant inputs. The total mean percent of clay grain-sized sediments at Kharg were 26.57% and 28.86% in dry and wet seasons, respectively, while in Lark were 26.73% in summer and 24.57% in winter. Additionally, at Kharg the mean ∑25n-alkanes and ∑30PAHs ranged from 81.35 to 573 µg g^-1 dw and 60.25-491 ng g^-1 dw in dry season, and 171-754 µg g^-1 dw and 41.61-693 ng g^-1 dw in winter, respectively. At Lark, the average ∑25n-alkanes and ∑30PAHs varied from 31.18 to 272 µg g^-1 dw and 41.25-196 ng g^-1 dw in summer, whilst oscillated from 57.99 to 332 µg g^-1 dw and 16.56-487 ng g^-1 dw in wet season, respectively. The lowest mean level of the examined pollutants were spanned in offshore sites, while the highest average concentrations indicated that contaminated sediments were at onshore stations at both Islands in both seasons. Significant seasonal variations (p < 0.05) were observed at most sampling sites for all pollutants. Molecular Diagnostic Ratio (MDR) and Principal Component Analysis (PCA) indicated that n-alkanes and PAHs had mostly a petrogenic source. The compositional profile of PAHs showed that 2 and 3-ring PAHs were abundant at both sampling sites. Significant positive correlation (r > 0.76) was observed between ∑25n-alkanes and ∑30PAHs at Kharg and Lark sediments with TOC content, especially for the sites with high total pollutant concentrations. Based on the potential impact and ecological risk of n-alkanes and PAHs in surface sediments, it is, therefore, necessary in future studies to focus on their effects on corals and other marine organisms within this ecosystem.

Brominated Flame Retardants, Microplastics, and Biocides in the Marine Environment: Recent Updates of Occurrence, Analysis, and Impacts

Emerging contaminants (ECs) may pose adverse effects on the marine ecosystem and human health. Based on the analysis of publications filed in recent years, this paper provides a comprehensive overview on three prominent groups of ECs, i.e., brominated flame retardants, microplastics, and biocides. It includes detailed discussions on: (1) the occurrence of ECs in seawater, sediment, and biota; (2) analytical detection and monitoring approaches for these target ECs; and (3) the biological impacts of the ECs on humans and other trophic levels. This review provides a summary of recent advances in the field and remaining knowledge gaps to address, to enable the assessment of risk and support the development of regulations and mitigation technologies for the control of ECs in the marine environment.

Selective detection of chloramphenicol based on molecularly imprinted solid-phase extraction in seawater from Jiaozhou Bay, China

This study highlights an efficient sample pre-treatment method for preconcentration and detection of chloramphenicol in marine water using molecularly imprinted solid-phase extraction (MISPE). Chloramphenicol molecularly imprinted microspheres were prepared and evaluated on the base of morphology, capacity and selectivity. The imprinted microspheres exhibited specific recognition and high retention capability to chloramphenicol and were applied as special solid-phase extraction adsorbents. An off-line MISPE protocol has been optimized and a creative analytical method coupled to HPLC-DAD was successfully developed for the cleanup and determination of chloramphenicol in seawater samples. Method performance was satisfactory with recoveries ranging from 81 to 90% and relative standard deviation (RSD) was <4.93% (n = 3). Accuracy of the method was assessed at three spiking concentration levels and the limit of detection was 5 ng L^-1. Finally, five seawater samples from Jiaozhou Bay of China were determined and the results showed that there was no chloramphenicol detected.

Is it photosensitization or photodegradation when UV-B irradiation is combined with BDE-47? Evidence from the growth and reproduction changes of rotifer Brachionus plicatilis

Ecotoxicological methods were applied in the present study, and the marine rotifer Brachionus plicatilis was used as the toxic endpoint to depict what occurred when 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) was combined with solar ultraviolet-B radiation (UV-B). B. plicatilis was exposed to three different combination methods of BDE-47 and UV-B at an equal toxicity ratio, including normal rotifer co-cultured with UV-B-irradiated BDE-47 (known as Method I), UV-B-irradiated rotifer co-cultured with BDE-47 exposure (known as Method II) and normal rotifer co-cultured with the simultaneous addition of BDE-47 and UV-B irradiation (known as Method III). Acute and chronic experiments were preformed to determine the toxicity differentiation according to the growth and reproduction changes in the rotifer. Twenty-four-hour acute experiments showed that the modes of three combined methods changed from antagonism to additive, to synergistic with the concentration/dose increment, and the contribution rates of Method I and Method II to Method III were calculated by approximately 40.4% and 59.6%, respectively. Chronic exposure to either the single stressor or the combination of stressors inhibited the growth and reproduction of the rotifer, demonstrating the inhibition of the population growth rate and the decrease in the larvae production. Three combined groups presented more serious damages compared to groups with single stress exposure, and the ascending sequence of toxicity was Method I<Method II<Method III. A higher bioaccumulation of BDE-47 was found in all combined groups than BDE-47 single stress group, and bioconcentration factor (BCF) general ranked Method II<Method I<Method III. Moreover, BDE-28, photodegradation production of BDE-47, were found in groups preformed Method I and III. We thus speculated that the toxicity enhancement when BDE-47 was combined with UV-B was mainly due to photosensitization and photodegradation, and the photosensitization might be more noxious to the growth and reproduction of the rotifer.

Polybrominated diphenyl ethers in the dissolved and suspended phases of seawater from Sanggou Bay, east China

The levels and profiles of polybrominated diphenyl ethers (PBDEs) in dissolved phase (DP) and suspended particulate matter (SPM) in seawater of Sanggou Bay (SGB) in four seasons were determined. The distribution and potential sources of these compounds were analyzed, and the ecological risk was assessed. The total concentrations of 14 PBDEs (∑₁₄PBDE) in DP and SPM in the surface water ranged from 0.10 ng L^-1 to 2.20 ng L^-1 and from 0.51 ng L^-1 to 6.15 ng L^-1, respectively. The highest value was obtained in August. The concentrations of ∑₁₄PBDE in the surface water were higher than those in the bottom water, and PBDEs were mainly partitioned into the SPM fraction. BDE209 was the most dominant PBDE congener, having average relative contributions of 86.5%-94.8% in DP and 40.5%-56.5% in SPM, followed by BDE47. The profiles of PBDEs in seawater of SGB were different from those of commercial PBDE products. The concentrations of ∑₁₄PBDE were higher in the inner bay than in the outer bay, suggesting that the terrestrial input and human activities affected the PBDE distribution in SGB. Results of nonparametric multidimensional scaling suggested that BDE209 and BDE47 were important congeners discriminating PBDE contamination in SGB. The potential sources of PBDEs in SGB included commercial PentaBDE and DecaBDE products from the land, the atmospheric transport of commercial OctaBDE, and the degradation of high brominated congeners. The ecological risks from PentaBDE and OctaBDE were low, and those from DecaBDE were moderate in seawater of SGB.

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.

Polybrominated diphenyl ethers (PBDEs) in water, surface sediment, and suspended particulate matter from the Yellow River, China: Levels, spatial and seasonal distribution, and source contribution

Fourteen polybrominated diphenyl ether (PBDE) congeners were measured in water, suspended particulate matter (SPM), and sediment samples collected from the entire expanse of the Yellow River in dry and wet seasons. Higher concentrations of PBDEs were found in the middle and lower reaches of the river compared with those in the upper reaches, ascribed to the relatively developed and urbanized cities located in the areas near the middle and lower reaches. The PBDE concentrations in the samples collected during the dry season were lower than those in the samples collected during the wet season because of thaw and rainfall. The dominant congener, with a contribution of 44.6-90.3%, was BDE-209, which originated from the residual of commercial deca-BDE. Three groups of congeners in all the samples showed good correlations with the coefficient ranging from 0.662 to 0.999 (p < 0.01), indicating common sources and similar environmental behaviors. Regression analysis suggested that the local industrial product (IP) and population density (PD) were good indicators of PBDEs in the water and sediment of the Yellow River.

Influence of human activities and organic matters on occurrence of polybrominated diphenyl ethers in marine sediment core: A case study in the Southern Yellow Sea, China

The Southern Yellow Sea (SYS) is an important reservoir of anthropogenic organic contaminants, such as polybrominated diphenyl ethers (PBDEs). To reconstruct the historical records of PBDEs and examine their relationships with the human activities and organic matters, a²¹⁰Pb-dated sediment core was collected from the central mud area in the SYS. The concentrations of tri-to hepta-BDEs (∑₇PBDEs) and BDE-209 ranged from 9.8 to 99.8 pg g^-1 d.w. and from 12.1 to 855.4 pg g^-1 d.w., respectively, both displaying the increasing trends from the bottom to the surface. More importantly, there was a faster increase for PBDEs since the 1990s, especially for BDE-209, which responded well with the rapid economic growth, and the increases of urbanization and industrialization in the local areas of the SYS. The analogously vertical patterns and significant relationships between PBDEs and total organic carbon (TOC) implied the TOC-dependent deposition of PBDEs in the core. Furthermore, multiple biomarker-based proxies of terrestrial organic matter (TOM) and marine organic matter (MOM) were introduced to systematically investigate the different effects of TOM and MOM on PBDE deposition in the SYS. The similarly down-core profiles and significant correlations were found between PBDEs and the MOM proxies (sum of rassicasterol, dinosterol and C₃₇ alkenones (∑A + B + D) and marine TOC) as well as the branched and isoprenoid tetraether (BIT), but not for TOM proxies (∑C₂₇+C₂₉+C₃₁n-alkanes, terrestrial and marine biomarker ratio (TMBR) and terrestrial TOC), indicating that MOM was an important factor driving PBDE deposition in the sediment core from the SYS.

Spatial distribution and composition of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons and hopanes in superficial sediments of the coral reefs of the Persian Gulf, Iran

This study is the first quantitative report on petroleum biomarkers from the coral reefs systems of the Persian Gulf. 120 reef surface sediment samples from ten fragile coral reef ecosystems were collected and analyzed for grain size, biogenic elements, elemental ratios, and petroleum biomarkers (n-alkanes, PAHs¹ and Hopanes) to assess the sources and early diagenesis of sedimentary organic matter. The mean grain size of the reef sediments ranged from 13.56 to 37.11% (Clay), 26.92 to 51.73% (Sand) and 35.97 to 43.85% (Silt). TOC² (3.35-9.72 mg.g^-1) and TON³ (0.4-1.10 mg.g^-1) were identified as influencing factors on the accumulation of petroleum hydrocarbons, whilst BC⁴ (1.08-3.28 mg.g^-1) and TIN⁵ (0.13-0.86) did not exhibit any determining effect. Although BC and TIN demonstrated heterogeneous spatial distribution, TOC and TON indicated homogenous distribution with continually upward trend in concentration from the east to west ward of the Gulf. The mean calculated TOC/TN ratios vacillated according to the stations (p < 0.05) from 2.96 at Shidvar Island to 8.64 at Hengam Island. The high TOC/TN ratios were observed in the Hengam (8.64), Kharg (8.04) and Siri (6.29), respectively, suggesting a predominant marine origin. The mean concentrations of ∑C_11-35n-alkanes, ∑30 PAHs and ∑9Hopanes were found in the ranges of 385-937 μg.g^-1dw, (overall mean:590 μg.g^-1dw), 326-793 ng.g^-1dw (499 ng.g^-1dw), 88 to 568 ng.g^-1 d (258 ng.g^-1dw), respectively. Higher concentrations of detected petroleum biomarkers in reef sediments were chiefly distributed near main industrial areas, Kharg, Lavan and Siri, whilst the lower concentrations were in Hormoz and Qeshm. In addition, one-way ANOVA⁶ analysis demonstrated considerably significant differences (p < 0.05) among concentration of detected total petroleum hydrocarbons between most sampling locations. Some sampling sites especially Kharg, Lavan, Siri and Lark indicated higher concentration of n-alkanes due to the higher maintenance of organic matter by high clay content in the sediments. Furthermore, most sediment samples, except for Hormoz, Qeshm and Hengam showed an even carbon preference for n-alkanes which could be correlated to bacterial input. NPMDS⁷ analysis also demonstrated that among the congeners of petroleum biomarkers, n-C₁₂,n-C₁₄, n-C₁₆,n-C₁₈ and n-C₂₀ for n-alkanes, Phe⁸ and Naph⁹ along with their Alkyl homologues for PAHs (2-3 rings accounted for 60%) and C₃₀αβ and C₂₉αβ for Hopanes were discriminated from their other congeners in the whole study area. Our results based on the PCA¹⁰ analysis and diagnostic indices of AHs¹¹ and PAHs along with ring classification of PAHs, in addition, the ubiquitous presence of UCM,¹² and Hopanes revealed that the main sources of the pollution were petroleum and petroleum combustion mainly from offshore oil exploration and extraction, discharge of pollutants from shipping activities.

Polybrominated diphenyl ethers in marine sediments of Sanggou Bay in east China

Polybrominated diphenyl ethers (PBDEs) were measured in the surface sediments collected in August 2015 in Sanggou Bay, China. The total concentrations of 13 PBDEs, including BDE-17, -28, -47, -66, -71, -85, -99, -100, -138, -153, -154, -183 and -190, and concentrations of BDE-209 were 0.223-1.259ng/g and 0.865-9.275ng/g, respectively. The PBDE levels increased from the outer bay to the inner bay. BDE-209 was the predominant congener, followed by BDE-47, BDE-71, and BDE-99. Significant positive correlations were observed for tri-BDEs with organic carbon (r=0.598, p<0.05) and with clay content (r=0.592, p<0.05). Principal component analysis revealed that PBDEs in Sanggou Bay were mainly derived from the usage, dismantling and degradation of commercial products (penta-, octa-, and deca-BDEs), which were then transported through continental runoff and atmospheric deposition. The ecological risks were mainly attributed to deca-BDE congeners with moderate risk level.

Characterization of PBDEs and novel brominated flame retardants in seawater near a coastal mariculture area of the Bohai Sea, China

The concentrations and distributions of PBDEs and novel brominated flame retardants (NBFRs) in dissolved phase of surface seawater near a coastal mariculture area of the Bohai Sea were investigated. The total concentrations of PBDE and NBFRs were in the range of 15.4-65.5 and 2.12-13.6ng/L, respectively. The highest concentration was discovered in the water near an anchorage ground, whereas concentrations in water samples from offshore cage-culture area were not elevated. Relatively high concentrations of BDE28, 99, and 100 were discovered in the medium range of distance from shore, where is the path of tidal or coastal current. This suggested that inputs from ships or through tidal current rather than mariculture activities may be the main sources of BFRs in this area. BDE209, BDE47, hexabromobenzene (HBB), and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) were the most abundant BFR congeners. Relatively high proportions of these BFRs may originate from discharge of wastewater nearby or degradation from higher brominated PBDEs. No correlations were found between BFR concentrations and water dissolved organic carbon, suggesting that concentrations and distributions of BFRs in this area were source-dependent. The relatively high concentrations in this study emphasized the importance of monitoring and managing BFR contaminations in mariculture areas of China.