Polybrominated diphenyl ethers occurrence in major inflowing rivers of Lake Chaohu (China): characteristics, potential sources and inputs to lake

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.

Degradation efficiency and mechanism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by thermally activated persulfate system

Polybrominated diphenyl ethers (PBDEs) as a typical brominated flame retardant (BFR) have attracted worldwide attention due to the high environmental risk and resistance to conventional remediation processes. In this study, thermally activated persulfate (TAP) process was applied to degrade 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), which is the most toxic and representative PBDEs in e-waste dismantling sites. Impact factors such as PDS dosage, heating temperature, and initial pH were evaluated. Results showed that BDE-47 can be 100% degraded within 180 min under the condition of PDS:BDE-47 = 1000:1, 60 °C, and pH = 7. Quenching experiments combined with EPR analysis further proved the important role of SO₄^·- in oxidating BDE-47. According to high-resolution mass spectrometry (HRMS) analysis, only one oxidation product of low toxicity was detected during the oxidation process. Theoretical calculations further revealed that the oxidation process mainly involved radical attack at C-Br bond, cleavage of C-Br bond, and fission of ether bond, and HSO₄· may also play an important role in BDE-47 degradation in TAP system. In addition, TAP system exhibited universality as all selected PBDE congeners can be degraded, and the degradation rate of PBDEs was greatly affected by the number of substituted Br atoms in a negative trend. Overall, these findings indicate that TAP can be applied as an effective method for removal of PBDEs, and we provide a new insight for the practical application of TAP technology in BDE-47 degradation from experimental and theoretical aspects.

Occurrence and ecological risk assessment of 2,2',4,4'-tetrabromodiphenyl ether and decabromodiphenyl ether in surface waters across China

Polybrominated diphenyl ethers (PBDEs) are efficient brominated flame retardants and are released into various environmental media via usage, recycling and disposal. This study investigated the concentrations and ecological risks of two typical PBDEs, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and decabromodiphenyl ether (BDE-209), in surface waters across China from 2011 to 2018. The results showed that the concentration of BDE-209 (8.25 ng L^-1) was higher than that of BDE-47 (1.02 ng L^-1), and the concentrations of BDE-47 and BDE-209 in the lakes (2.56 ng L^-1 and 22.19 ng L^-1, respectively) were higher than those in the rivers (0.58 ng L^-1 and 7.05 ng L^-1, respectively). In addition, the concentration of BDE-209 in the wet season (2.61 ng L^-1) was lower than that in the dry season (10.83 ng L^-1), whereas the concentration of BDE-47 in the wet season (0.24 ng L^-1) was a little lower than that in the dry season (0.99 ng L^-1). BDE-47 and BDE-209 concentrations showed a gradual decrease in surface waters across China during the eight-year period. Based on the species sensitivity distribution (SSD) models, the 5% hazardous concentration (HC₅) and predicted no-effect concentration (PNEC) values were derived using the acute and chronic toxicity data of BDE-47 and BDE-209. Results showed that the PNEC values based on the acute and chronic toxicity data were 2.08 μg L^-1 and 0.52 μg L^-1 for BDE-47, respectively and 370 μg L^-1 and 0.34 μg L^-1 for BDE-209, respectively. The risk quotient (RQ) values of BDE-47 in surface waters across China were far smaller than 0.1 (low ecological risk). Similarly, the RQ values of BDE-209 were also smaller than 0.1, except for those at Baiyangdian Lake and Chaohu Lake, where the probability of 0.1 ≤ RQ < 1.0 (medium ecological risk) was approximately 10% based on 10,000 Monte Carlo simulations.

Accumulation of microplastics in fish guts and gills from a large natural lake: Selective or non-selective?

In recent years, microplastics (MPs) have become emerging contaminant causing widespread concern about their ecotoxicological effects. However, little is known regarding the accumulation of MPs in different tissues of fishes, especially for freshwater fishes in natural environments. In this study, MPs in guts and gills of 11 fish species from Lake Chao, China were examined to explore the accumulation differences and foraging preferences of MPs. In general, MPs in fish guts varied from 2.85 to 8.38 items/individual, while ranged from 3.06 to 8.90 items/individual in fish gills. In terms of characteristic composition (shape, color, size, and polymer type), our results demonstrate higher occurrence of fibrous, black, small sized (<1 mm), and polypropylene MPs. Meanwhile, MPs concentrations in fish guts differed significantly among various feeding groups, with none significant difference detected in fish gills. In addition, fish guts exhibit more distinct foraging preferences for specific featured MPs in contrast with fish gills. These results indicate selective MPs accumulation in fish guts whereas random MPs accumulation in fish gills. Fish gills, adhering MPs by non-selective water exchange, may be more related to the real-time MPs abundance in water. To some extent, fish gills may be employed as important instruments to reflect MPs contamination in aquatic environments. Influenced by diverse feeding behaviors such as visual cues and sensory systems, MPs accumulation in fish guts reflect intrinsic differences, thus making fish guts sensitive organ in monitoring MPs' ecological risk for their health.

Seasonal variation and ecological risk assessment of microplastics ingested by economic fishes in Lake Chaohu, China

Microplastic (MP) contaminations in freshwater organisms have attracted substantial attention worldwide. However, seasonal field studies of MPs concentrations in aquatic life are scarce. In this study, we analyzed the seasonal variation and ecological risk of MPs concentrations in economic fish species from Lake Chaohu in China between wet and dry seasons. Within both seasons, MPs in fish were systematically analyzed using methods of KOH digestion, NaCl density floatation and raman spectroscopy. MPs abundance in economic fishes were significantly higher in dry season than that in wet season, which can be ascribed to the MPs' amplification effects in lacustrine ecosystems during dry season. Whereas, our results recorded similar and homogenized characteristic composition of MPs in economic fishes between wet and dry seasons. In both seasons, fiber was the main morphological type, black and blue were the most common MPs color, and MPs ranging from <0.5 mm accounting for the most abundant size. In addition, polypropylene (PP) and polyethylene terephthalate (PET) accounted for the most abundant polymer type detected by economic fishes in both seasons. In terms of feeding groups and habitat preferences, planktivorous and pelagic fish species exhibited sensitive variations of MPs concentrations between wet and dry seasons, thus being highlighted as good bioindicators of MPs contaminants in freshwater ecosystems. Our results revealed higher ecological risks of MPs in wet season than that in dry season when indicating from polymer risk index (H). By providing detailed and direct toxicity information, our study highlights the usage of polymer risk index for ecological risk assessment in aquatic organisms.

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.

Establishment of a comprehensive method to derive seawater quality criteria of BDE-47 in China

2,2',4,4'-tetrabromodiphenyl ether (BDE-47) is an emerging toxic organic pollutant widely detected in territorial waters. Accordingly, establishing the seawater quality criteria (SWQC) for BDE-47 is of significant importance to protect the marine ecosystems. In this study, published ecotoxicity data of BDE-47 to aquatic species in China were collected, and acute and chronic toxicity tests were carried out on saltwater aquatic organisms from 5 phyla and 8 families widely existed in the Chinese marine environment. Static acute toxicity tests and renewed chronic toxicity tests were adopted. The scientific theories and technical methods of the United States Environmental Protection Agency (US EPA), Canada, the European Union (EU), and the Netherlands on water quality criteria guidelines, as well as the Chinese freshwater quality criteria guidelines were compared. Then an integrated method of SWQC derivation was introduced through comprehensive consideration. Afterward, the SWQC of BDE-47 was derived based on the ecotoxicity data. The SWQC includes short-term seawater quality criteria (S-SWQC), long-term seawater quality criteria (L-SWQC), and serious risk concentration for the ecosystem (SRC_eco). And they were derived and recommended as 7.90 μg/L, 0.217 μg/L, and 3.65 μg/L, respectively. This study served as a specific example to quantitatively studies the differences between different scientific theories and technique methods. The derivation process and improvement of SWQC for BDE-47 provide support for the future revision of water quality criteria in China.

Dynamic variations of cyanobacterial blooms and their response to urban development and climate change in Lake Chaohu based on Landsat observations

Recurring cyanobacterial blooms have seriously hindered the sustainable development of cities. In this study, the variation trend of cyanobacterial blooms was analyzed by taking Lake Chaohu in China as the study area, and the Normalized Difference Vegetation Index (NDVI) derived from Landsat observations combined with the development index of surrounding cities from 2009 to 2019 was used to quantitatively analyze the response of cyanobacterial blooms to urban development and climate change. The results showed that the NDVI of the Northwest Lake region was significantly higher than that of other regions. Summer and autumn were the main seasons for the outbreak of cyanobacterial blooms. The NDVI of Lake Chaohu and Baohe Lake region showed a significant correlation with the gross domestic product (GDP) growth rate of Hefei city (HF), the districts and counties around the lake (DCL), Baohe District (BH), and the population (P). As the economic regions gradually focused on BH rather than on HF and DCL, there was an increasing trend correlation between the NDVI of Baohe Lake region and the GDP growth rate. However, the elimination of GDP in BH did not affect the consistency relationship between the economic growth of other regions and the NDVI of Lake Chaohu on a large scale. In addition, the results of relative importance analysis indicated that the GDP growth rate of BH and the area of Hefei except DCL (HF-DCL) accounted for important contribution to the [Formula: see text] of the regression. This study has momentous reference value for understanding the coupling relationship between urban development and lake environment.

Perfluorinated compounds in a river basin from QingHai-Tibet Plateau: Occurrence, sources and key factors

The occurrence of perfluorinated compounds (PFCs) in different environmental media in the QingHai-Tibet Plateau has been limitedly investigated. In this study, the water, sediments, soils and agricultural product samples were collected in the Huangshui River basin, and contents of the PFCs and values of water parameters were determined. This study investigated dominantly regulating factors of the distribution of PFCs in the water emphatically, explored the sources and assessed potential risks of the PFCs integrally. The results showed that perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, perfluorobutanoic acid (PFBA) and perfluorooctanoic acid presented high maximum concentrations of 3207.42, 3015.96, 1941.89 and 826.4 ng L-1 in the water, respectively. There were 12 PFCs detected in crops, with the maximum concentration of 5206.86 ng g-1 for PFBA. The significantly positive correlation (p < 0.05) was observed between the concentrations of PFBA in crops and that in adjacent rivers, indicating that the irrigation most likely contributed to the accumulation of PFBA in the studied crops. The occurrence of the PFCs in the water during the dry season was dominantly regulated by fluorescent dissolved organic matters via the hydrophobic interaction, while it was primarily regulated by the total nitrogen and electrical conductivity via electrostatic interaction during the wet season. The PFCs in the water were mainly from the wastewater discharged from wastewater treatment plants and carpet factories, while the resuspension of the PFCs in sediments was also an important contribution especially in wet season. The PFCs in the river has posed sustained risk to the public health, especially children.

Optimized remote sensing estimation of the lake algal biomass by considering the vertically heterogeneous chlorophyll distribution: Study case in Lake Chaohu of China

Due to the difference of vertical distribution of algae in lakes, it is necessary to carry out remote sensing estimation of algal biomass based on the vertically heterogeneous distribution of chlorophyll in order to improve the accuracy of biomass inversion. A new algorithm is proposed and validated to measure algal biomass in Lake Chaohu based on the Moderate Resolution Imaging Spectrometer (MODIS) images. The algal biomass index (ABI) is defined as the difference in remote-sensing reflectance (R_rs, sr^-1) at 555 nm normalized against two baselines with one formed linearly between R_rs(859) and R_rs(469) and another formed linearly between R_rs(645) and R_rs(469). Both theory and model simulations show that ABI has a good relation with the algal biomass in the euphotic zone (R² = 0.88, p < 0.01, N = 50). Field data were further used to estimate the biomass outside the euphotic layer through an empirical algorithm. The ABI algorithm was applied to MODIS Rayleigh-corrected reflectance (R_rc) data after testing the sensitivity to sun glint and thickness of aerosols, which showed an acceptable precision (root mean square error < 21.31 mg and mean relative error < 16.08%). Spectral analyses showed that ABI algorithm was immune to concentration of colored dissolved organic matter (CDOM) but relatively sensitive to suspended particulate inorganic matter (SPIM), which can be solved by using Turbid Water Index (TWI) though in such a challenging environment. A long-term (2012-2017) estimation of algal biomass was further calculated based on the robust algorithm, which shows both seasonal and spatial variations in Lake Chaohu. Tests of ABI algorithm on Sentinel-3 OLCI demonstrates the potential for application in other remote sensors, which meets the need of observation using multi-sensor remote sensing in the future.

Polybrominated diphenyl ethers (PBDEs) concentrations in soil and plants around municipal dumpsites in Abuja, Nigeria

Polybrominated diphenyl ethers (PBDEs) are listed as persistent organic pollutants (POPs) in the Stockholm Convention. It has been established that PBDEs may be released into the environment during improper handling and disposal of e-waste and other products containing PBDEs that is prevalent in developing countries. This research work assessed the status of PBDE contamination at dumpsites in Nigeria. Soil and edible plant samples were collected from the dumpsites and control sites for analysis. The concentrations of ∑₇PBDE in the topsoils around the dumpsites at 0-15 cm depth ranged from 112 to 366 ng/g dry weight (dw) while that of the topsoil of the control site 500 m from the dumpsite ranged from 26.8 to 39.7 ng/g dw. These high concentrations stem likely from open burning of waste including electronic waste on the landfills. Plant samples (bentgrass, spinach, tomatoes, pumpkin and sweet potatoes) around the dumpsites were found to be contaminated by PBDEs with levels ranging from 25.0 to 60.5 ng/g dw in plant roots and from 8.45 to 32.2 ng/g dw in plant shoots for ∑₇PBDE. This suggests that consumption of vegetables by humans and ingestion of contaminated soils and feed by chickens and cows can transfer PBDEs into the human food chain around the dumpsites. The comparison of PBDE levels in soils and the PBDE levels in chicken eggs from the former study indicate that PBDE levels in the soils are sufficient to explain the levels in the chicken eggs with a reasonable carry-over rate for PBDEs of 0.28 on average. The PBDE contamination in the soil was sufficient to result in a relevant exposure of humans via accumulation in eggs. The study shows that a better management of end-of-life products containing PBDEs is needed to reduce PBDE exposure risk in Africa.

Occurrence, distribution and partitioning of polychlorinated dibenzothiophenes (PCDTs) in Chaohu Lake, Southeast China

Polychlorinated dibenzothiophenes (PCDTs) are a class of compounds structurally similar to dioxins that possess various toxicological impacts on living organisms. Unfortunately, information on the levels of PCDTs in freshwater lakes in China is still scarce. In this work, the occurrence of 14 congeners of PCDTs in different matrices (i.e., sediment, suspended particulate matter (SPM), and water) of Chaohu Lake was investigated. It was determined that the concentrations of 14 PCDTs (Σ₁₄PCDTs) in the sediment, SPM, and surface water were 0.40-3.55 ng g^-1 (dry weight, d.w.), 0.38-2.95 ng·g^-1 d.w., and 0.34-2.61 ng L^-1, respectively. The dominant congener found in sediments was 1,2,3,4,7-penta-CDT (19.54%), and 1,3,9-tri-CDT was the predominant congener in SPM (19.13%) and water (20.08%). Medium- and high-chlorinated PCDTs were detected as the major compounds in sediments and SPM. The low-chlorinated PCDTs (e.g., mono-CDTs) have higher relative percentages in the water than those detected in the sediment samples. The annual Σ₁₄PCDT input of the eight main tributaries to Chaohu Lake was 19.90 kg. A strong linear correlation between the Σ₁₄PCDT levels and the organic carbon (OC) content demonstrated that OC had an important influence on the PCDT redistribution in Chaohu Lake. In addition, the organic carbon normalized partitioning coefficient (logK_OC) of PCDTs in the SPM-water system in Chaohu Lake was 1.95-2.49 mL g^-1, and correlations between logK_OC and other typical environment-related properties of PCDTs were established. This study provided useful data on the evaluation of ecological risks of PCDTs in Chaohu Lake.

Levels of polybrominated diphenyl ethers (PBDEs) in water and sediment from open city drains in Makurdi Metropolitan Area, North Central Nigeria

Polybrominated diphenyl ethers (PBDEs) have been classified as persistent organic pollutants (POPs) as well as endocrine-disrupting compounds (EDCs). This study determined the concentrations of six PBDE congeners (BDE 47, BDE 99, BDE 100, BDE 153, BDE 154, and BDE 183) in water and sediment samples from open city drains, in the Makurdi Metropolitan Area, North Central Nigeria, using gas chromatogragh-mass spectrometer. These congeners are components of the penta- and octa-BDE formulations that have been banned by the European Union. The samples were collected from the drains, bi-monthly, for 1 year across dry and wet seasons. All the congeners considered were found to be present in both water and sediment. The levels of Σ₆PBDEs in water ranged from 0.05 to 0.28 ng L^-1 during dry season and 0.02 to 0.36 ng L^-1 during wet season, while their levels in sediment during dry and wet seasons ranged from 3.22 to 26.26 ng g^-1 and 7.51 to 27.41 ng g^-1, respectively. The percentage recoveries from solid phase and Soxhlet extractions ranged from 69 to 104% and 70 to 112%, respectively. It was concluded that the presence of all the congeners in both water and sediment posed a pollution risk to the river in which the drains discharge and require further monitoring and necessary preventive measures.

Determination of Polybrominated Diphenyl Ethers in Water Samples Using Effervescent-Assisted Dispersive Liquid-Liquid Icroextraction with Solidification of the Aqueous Phase

An effective and sensitive method is necessary for the determination of polybrominated diphenyl ethers (PBDEs) pollutants in water. In this study, effervescent-assisted dispersive liquid-liquid microextraction with solidification of the aqueous phase (EA-DLLME-SAP), followed by Gas Chromatography-Tandem Mass Spectrometry (GC-MS-MS) quantitative analysis, was established for the preconcentration and determination of PBDEs in real environmental water samples. 1,1,2,2-Tetrachloroethane was used as the extractant and directly dispersed into the water phase of the aqueous samples with the aid of a large number of carbon dioxide bubbles generated via the acid-base reaction of acetic acid and sodium bicarbonate, which did not require the use of a dispersant during the extraction process. The key factors affecting the extraction recovery were optimized, and an internal standard was used for quantitative analysis, which gave good linearity ranges of 1-100 ng·L^-1 (BDEs 28, 47, 99, and 100), 2-200 ng·L^-1 (BDEs 153, 154, and 183) and 5-500 ng·L^-1 (BDE 209) with limits of quantification in the range of 1.0-5.0 ng·L^-1. The accuracy was verified with relative standard deviations < 8.5% observed in tap, lake, river and reservoir water samples with relative recoveries ranging from 67.2 to 102.6%. The presented method contributes to the determination of PBDEs in environmental water samples.

Synthetic musk fragrances in sediments from a subtropical river-lake system in eastern China: occurrences, profiles, and ecological risks

Synthetic musk fragrances (SMFs) in aquatic environments have been of increasing concern because of their potential characteristic of persistent, bioaccumulated, and ecological harm. However, little is known about the distribution of SMFs in river-lake systems. In this study, the occurrence and risks of six SMFs measured in sediments from Lake Chaohu (eastern China) and the rivers flowing into it were investigated. The total sedimentary SMF concentrations ranged from 2.43 to 15.5 ng/g in Lake Chaohu (median = 5.17 ng/g), and 2.34-104 ng/g in the rivers (median = 10.6 ng/g). Overall, moderate levels of SMFs were found in comparison with previous results from other areas. Galaxolide and tonalide dominated in the rivers whereas cashmeran was dominant in Lake Chaohu. A source assessment indicated that the discharge from industries contributed importantly to the pollution of SMFs in the studied waters, in addition to the inputs from domestic sewage. Our estimates suggested that the current sedimentary SMF concentrations were likely to pose extremely low ecological risk to aquatic organisms. However, more studies are needed to focus on the spatial and temporal trends in distribution as well as the ecotoxicological implications of SMFs in the Lake Chaohu area because there is a general lack of relevant information.

Polybrominated diphenyl ethers (PBDEs) in the Danjiangkou Reservoir, China: identification of priority PBDE congeners

Although the production of polybrominated diphenyl ethers (PBDEs) has been phased out over the past decade worldwide, they are still potentially hazardous to the environment due to their persistence and toxicity. This study investigated the levels of 55 PBDEs in water and sediments from the Danjiangkou Reservoir, China. The levels of PBDEs were in the range of not detected (ND)-286.67 ng/L in water and ND-236.04 ng/g in sediments. BDE209 was the predominant PBDE congener and constituted 15-50% and 44-68% of the total PBDEs in water and sediments, respectively. Commercial pentaBDE products (70-5DE, DE-71) were the dominant source of tetraBDE, pentaBDE, and hexaBDE, while commercial octaBDE (79-8DE) and decaBDE (102E and 82-0DE) products were the main sources of nonaBDE and decaBDE in water. PBDEs in sediments mainly stemmed from commercial decaBDE products and combustion sources. BDE-209 posed high ecological risks to aquatic organisms and dominated the total ecological risks of PBDEs. No cancer risks and non-cancer risks were observed for PBDEs. A ranking method based on four criteria, i.e., detection frequency, concentration, ecological risk, and health risks, was proposed, and 17 PBDEs were identified as high priority PBDEs for future monitoring and management in the Danjiangkou Reservoir.

Linking bacterial community shifts with changes in the dissolved organic matter pool in a eutrophic lake

Aquatic bacterial communities play crucial roles in the circulation of nutrients in watershed ecosystems. However, the interaction between bacterial communities and chromophoric dissolved organic matter (CDOM) in freshwater ecosystems has not been studied in depth. In our study, we examined the constitution and interactions of CDOM with the bacterial community in Lake Chaohu and its inflow rivers under the influence of different exogenous pollutants. The results revealed that the bacterial community diversity in the inflow rivers was significantly lower than that in the lake sites. Clustering of different types of polluted inflow rivers integrated with the most abundant genera observed in specific areas indicated that environmentally guided species selection had a large impact on the composition of aquatic bacterial communities. Moreover, our study suggests that communities in lake environments may be more susceptible to interference through a variety of physiologies or via functional redundancy, allowing them to preserve their community structure. Through linear discriminant analysis effect size (Lefse) methods, we revealed that some taxa (from phylum to genus) were consistently enriched in the lake sites. Based on correlation network analysis results, the supersession niches of bacterial community members related to different CDOM in the biogeochemical process was determined. This study provides an ecological basis for the control of external pollution and the protection of the water environment in watershed ecosystems.

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.

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.

Persistent Halogenated Organic Pollutants in Surface Water in a Megacity: Distribution Characteristics and Ecological Risks in Wuhan, China

Surface water pollution in megacities is strongly linked to human and environmental health, and surface water quality has deteriorated sharply recently because of increasing persistent halogenated organic pollutant (HOP) concentrations. In the present study, we collected 112 water samples from 14 lakes and 11 drinking water sources in Wuhan, China, and analyzed them for two typical groups of HOPs: polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The mean values of the ΣPCB concentrations were 4.34 and 10.05 ng L^-1 in winter and summer, respectively. For ΣPBDE concentrations, the mean values were 0.88 and 1.53 ng L^-1 in winter and summer, respectively. The PCB and PBDE concentrations at most sites in summer were significantly higher than those in winter, probably because of heavy stormwater runoff in summer. The degree of urbanization predicted from the population density was positively correlated with ΣPCB concentrations in the drinking water sources in summer. PBDE and PCB composition analysis suggested the major sources were penta-BDE and Aroclor mixtures. Risk assessments showed the PBDEs in water from the Zhuankou site exceeded the threshold set by the European Union, which could result in adverse effects on aquatic organisms. Negligible noncarcinogenic risks were found for PCBs and PBDEs in the surface water with regard to drinking and bathing. However, the carcinogenic risks of PCBs for bathing in surface water were higher than the safe level of 1.00 × 10^-6, implying that the surface water in Wuhan is not safe for bathing.

Occurrence, Removal and Bioaccumulation of Perfluoroalkyl Substances in Lake Chaohu, China

The perfluoroalkyl substances (PFAAs) have received growing attention in recent years as emerging contaminants in the aquatic environment. The occurrence, removal and bioaccumulation of fourteen PFAAs (C4-C14 carboxylate; C4, C6, C8 sulfonates) were investigated in Lake Chaohu, China. The concentrations of the selected PFAAs in inflowing river, lake water and sewage treatment plant (STP) samples were analyzed by ultra performance liquid chromatograph (UPLC-MS/MS). The results showed that perfluorohexanesulfonic acid (PFHxS), perfluorobutane sulfonate (PFBS), perfluorobutyric acid (PFBA) and perfluoropentanoic acid (PFPeA), instead of perfluorooctanoic acid (PFOA), were predominant PFAAs in the inflowing river and lake water with maximum concentrations in the ranges of 52.2-1866 and 27-236 ng L^-1, respectively. The highest concentrations of total PFAAs were detected in the western rivers. The effluents from seven STPs were likely important sources of PFAAs in surface water, and the amount of the daily fluxes in the effluent were 132 g for short-chain PFAAs and 109 g for long-chain PFAAs. PFAAs were widely detected in Chinese icefish (Neosalanx tangkahkeii taihuensis) collected from Lake Chaohu, with maximal concentrations ranging from 1.79 ng g^-1 to 50.9 ng g^-1. The logarithmic bioaccumulation factors of perfluorodecanoic acid (PFDA, 3.5), perfluorooctane sulfonate (PFOS, 3.35) and perfluorononanoic acid (PFNA, 3.31) indicated the bioaccumulation of these long-chain PFAAs. This study is useful for enhancing our understanding of the pollution profiles of PFAAs and their environmental health risk in the freshwater lake.

Concentrations and tissue-specific distributions of organic ultraviolet absorbents in wild fish from a large subtropical lake in China

Organic ultraviolet absorbents (UVAs) have been detected in various materials and biota, but little is known about the distributions of UVAs in the tissues of biota. In this study, tissue-specific UVA accumulation in six fish species from Lake Chaohu, China, was investigated. The sums of 12 UVA concentrations in muscles, gills, and livers were 7.65-120, 10.1-281, and 26.4-359 ng/g dry weight, respectively. Ethylhexyl methoxycinnamate, 4-methylbenzylidene-camphor, and 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole were the dominant UVAs. Ethylhexyl salicylate and homosalate have been found in the aquatic species firstly. UVAs were taken up to different degrees by different fish species. The UVA muscle bioconcentration factors were lower than predicted by the Estimation Programs Interface Suite model, suggesting that such models may overestimate UVA accumulation in fish. The tissue distribution patterns indicated that UVAs are easily transferred to the muscles after being absorbed through the gills. The liver was found to preferentially accumulate UVAs and have a high UVA accumulation capacity, implying liver damage may be caused by UVAs. This is the first time the partitioning of UVAs between the liver, muscle, and gills of freshwater fish has been studied. The data acquired will improve our understanding of the pharmacokinetics and toxicities of UVAs in aquatic organisms.

Occurrence, distribution and ecological risk of ultraviolet absorbents in water and sediment from Lake Chaohu and its inflowing rivers, China

The available information is insufficient to enable a reliable understanding of the global distribution and effect of organic ultraviolet absorbents (UVAs) on ecosystems. Little is known about the pollution of China's lakes by these chemicals. We conducted a survey of UVAs in water and sediment from Lake Chaohu and its inflowing rivers. The UVAs were widely present in this area and the concentrations of total 12 UVAs (Σ₁₂ UVAs) ranged between 162 and 587 ng/L in water and 9.70-178 ng/g in sediment. Benzophenone and benzophenone-3 were dominant in water, and benzophenone and octocrylene dominated in sediment. Higher concentrations of benzophenone were detected in the investigated water samples, although the contamination levels of UVAs in this study were comparable to those investigated in other areas. In addition to the inputs from the UVAs used as filters in cosmetics, the discharge from industries using UVAs as stabilizers also contributed much to the pollution in the study waters. Generally, the risk to aquatic organisms from exposure to UVAs in this area was low, but further research is needed to elucidate the fate of UVAs and to understand bioaccumulation and associated risks.

Polychlorinated diphenyl ethers (PCDEs) in surface sediments, suspended particulate matter (SPM) and surface water of Chaohu Lake, China

Polychlorinated diphenyl ethers (PCDEs) are typical halogenated aromatic pollutants that have shown various toxicological effects on organisms. However, the contamination status of PCDEs in the fresh water lakes of China remains poorly researched. In this study, the levels of 15 congeners of PCDEs in the sediments, suspended particulate matter (SPM) and water of Chaohu Lake were determined. The results showed that the ranges of concentrations of total PCDEs (ΣPCDEs) in the sediment, SPM and water were 0.279 ng g^-1 dry weight (d.w.)-2.474 ng g^-1 d.w., 0.331 ng g^-1 d.w.-2.013 ng g^-1 d.w. and 0.351 ng L^-1-2.021 ng L^-1, respectively. The most abundant congeners found in sediments, SPM and water were 3,3',4,4'-tetra-CDE, deca-CDE and 2,4,6-tri-CDE, with average contributive ratios of 17.36%, 15.48% and 20.63%, respectively. The medium and higher chlorinated PCDEs (e.g., penta- and deca-CDEs) were the dominant congeners in sediments and SPM. The percentages of lower chlorinated PCDEs (e.g., tri-CDEs) in the water were higher than those in the sediments. The combined input of ΣPCDEs from the eight main tributaries to Chaohu Lake was estimated at 6.94 kg y^-1. Strong linear correlations between the concentrations of ΣPCDEs and organic carbon (OC) contents in three type samples from Chaohu Lake suggested OC could influence the distribution of PCDEs in Chaohu Lake substantially. In addition, the calculated average organic carbon normalized partition coefficients (logK_oc) of 15 PCDEs between water and SPM were in the range of 4.55-5.45 mL g^-1. This study confirmed that Chaohu Lake is contaminated by PCDEs.

Polybrominated Diphenyl Ethers (PBDEs) in a Large, Highly Polluted Freshwater Lake, China: Occurrence, Fate, and Risk Assessment

Polybrominated diphenyl ethers (PBDEs) were extensively investigated in water, sediment, and biota samples collected from Chaohu Lake basin in China. The total concentrations of eight PBDEs (Σ₈PBDEs) were in the ranges of 0.11–4.48 ng/L, 0.06–5.41 ng/g, and 0.02–1.50 ng/g dry weight (dw) in the water, sediment, and biota samples, respectively. The concentrations showed wide variations in the monitoring area, while the congener profiles in all the water, sediment, and biota samples were generally characterized by only a few compounds, such as BDE-47, BDE-99, and/or BDE-209. The spatial analysis depicted a decreasing trend of PBDEs from west to east Chaohu Lake, consistent with regional industrialization degree. The distributions of PBDE congeners in the biota samples were similar to the compositional profiles in the water, which were dominated by BDE-47 and/or BDE-99. Nevertheless, BDE-47 and BDE-153 in the brain tissue showed a higher accumulative potential than PBDEs in other tissues as well as the whole body, with 96% relative contribution of Σ₈PBDEs. The noncarcinogenic risk values estimated for BDE-47, BDE-99, and BDE-153 indicated that the specific risk associated with the studied water and foodstuffs is limited. However, there is a potential mixture ecotoxicity at three trophic levels at some sampling points in the water, which should draw considerable attention.

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.

Long-term variation in concentrations and mass loads in a semi-arid watershed influenced by historic mercury mining and urban pollutant sources

Urban watersheds are significantly anthropogenically-altered landscapes. Most previous studies cover relatively short periods, without addressing concentrations, loads, and yields in relation to annual climate fluctuations, and datasets on Ag, Se, PBDEs, and PCDD/Fs are rare. Intensive storm-focused sampling and continuous turbidity monitoring were employed to quantify pollution at two locations in the Guadalupe River (California, USA). At a downstream location, we determined loads of suspended sediment (SS) for 14yrs., mercury (HgT), PCBs, and total organic carbon (TOC) (8yrs), total methylmercury (MeHgT) (6yrs), nutrients, and trace elements including Ag and Se (3yrs), DDTs, chlordanes, dieldrin, and PBDEs (2yrs), and PCDD/Fs (1yr). At an upstream location, we determined loads of SS for 4yrs. and HgT, MeHgT, PCBs and PCDD/Fs for 1yr. These data were compared to previous studies, climatically adjusted, and used to critically assess the use of small datasets for estimating annual average conditions. Concentrations and yields in the Guadalupe River appear to be atypical for total phosphorus, DDTs, dieldrin, HgT, MeHgT, Cr, Ni, and possibly Se due to local conditions. Other pollutants appear to be similar to other urban systems. On average, wet season flow varied by 6.5-fold and flow-weighted mean (FWM) concentrations varied 4.4-fold, with an average 7.1-fold difference between minimum and maximum annual loads. Loads for an average runoff year for each pollutant were usually less than the best estimate of long-term average. The arithmetic average of multiple years of load data or a FWM concentration combined with mean annual flow was also usually below the best estimate of long-term average load. Mean annual loads using sampled years were also less than the best estimate of long-term average by a mean of 2.2-fold. Climatic adjustment techniques are needed for computing estimates of long-term average annual loads.

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

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

Uptake, translocation and metabolism of decabromodiphenyl ether (BDE-209) in seven aquatic plants

Terrestrial plant uptake of PBDEs from contaminated soils has been widely reported recently. In this study the fate of deca-BDE within a plant/PBDEs/aquatic environment system was investigated through simulated pot experiments. Accumulations of the total PBDEs and deca-BDE were observed in tissues of seven test aquatic plant species, namely Phragmites australis, Cyperus papyrus, Alternanthera philoxeroides, Colocasia esculenta, Scirpus validus, Acorus calamus and Oryza sativa. In all seven plants, O. sativa leads the uptake and accumulation both in the total PBDEs (444.8 ng g(-1)) and deca-BDE (368.0 ng g(-1)) in roots. Among the six common phytoremediation aquatic plants, A. calamus leads the uptake (236.2 ng g(-1)), and P. australis leads the translocation (Cshoot/Croot = 0.35), while A. philoxeroides (43.4%) and P. australis (80.0%) lead in the metabolism efficiencies in the root and shoot, respectively. The detection of seventeen lesser brominated PBDE congeners provided the debromination evidence, and the specific PBDEs profiles in test plant species indicated there is no common metabolic pattern. Furthermore, a relative high proportion of lesser brominated PBDE congeners in shoots suggested the possible metabolic difference between roots and shoots. Finally, a noticeable percentage of penta- and octa-BDE derived from deca-BDE also hint the ecological risk in deca-BDE use. This comparative research on the aquatic plants provide a broad vision on the understanding of plant/PBDEs/aquatic environment interaction system, and may be applied to remediate PBDEs in contaminated waters and sediments.

Brominated flame retardants (BFRs): A review on environmental contamination in China

Brominated flame retardants (BFRs) which were detected extensively in environmental and biota samples worldwide, have raised significant concerns during past decades for their persistence, bioaccumulation and potential toxicity to ecological environment and human health. In this paper, we have compiled and reviewed existing literature on the contamination status of BFRs in abiotic and biotic environments in China, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane, tetrabromobisphenol A and new BFRs. Temporal trends were also summarized and evaluated. Based on this review, it has been concluded that (1) high concentrations of PBDEs were generally related to the e-waste disposal processing, while the spatial distribution pattern of other BFRs was not necessarily in accordance with this; (2) extremely high concentrations of BFRs in indoor dust emphasized the importance of indoor contamination to human body burdens, while more work need to be done to confirm its contribution; (3) PBDEs in electronics dismantling workers were higher compared to the general population, indicating the occupational exposure should be of particular concern; (4) more data are now becoming available for BFRs in aquatic and terrestrial organisms not previously studied, while studies that consider the occurrence of BFRs in organisms of different trophic levels are still of urgent need for evaluating the fate of BFRs in the food web; and (5) limited data showed a decreasing trend for PBDEs, while more data on time trends of BFR contamination in various matrices and locations are still needed before the impact of regulation of BFRs can be assessed.

Historical records of polycyclic aromatic hydrocarbon deposition in a shallow eutrophic lake: Impacts of sources and sedimentological conditions

Sediment core samples collected from Lake Chaohu were analyzed for 15 priority polycyclic aromatic hydrocarbons (PAHs) to assess the spatial and temporal distributions of the PAHs during lacustrine sedimentary processes and regional economic development. Assessing the PAH sedimentary records over an approximately 100-year time span, we identified two stages in the PAH inputs and sources (before the 1970s and after the 1970s) in the eastern lake region near a village, whereas three stages (before the 1950s, 1950s-1990s and after the 1990s) were identified in the western lake region near urban and industrial areas. Rapid increases in the PAH depositional fluxes occurred during the second stage due to increased human activities in the Lake Chaohu basin. The composition and isomeric ratios of the PAHs revealed that pyrolysis is the main source of PAHs in this lake. Strong positive relationships between PAH concentration and the total organic carbon concentration, sediment grain size (<4μm), as well as the local population and Gross Domestic Product indicated that the sedimentary conditions impact the depositional characteristics of the PAHs; simultaneously, socioeconomic activities, such as energy consumption and the levels of urban industrialization and civilization, affect both the composition and abundance of the PAHs.

Concentrations and loads of PCBs, dioxins, PAHs, PBDEs, OC pesticides and pyrethroids during storm and low flow conditions in a small urban semi-arid watershed

Urban runoff has been identified in water quality policy documents for San Francisco Bay as a large and potentially controllable source of pollutants. In response, concentrations of suspended sediments and a range of trace organic pollutants were intensively measured in dry weather and storm flow runoff from a 100% urban watershed. Flow in this highly urban watershed responded very quickly to rainfall and varied widely resulting in rapid changes of turbidity, suspended sediments and pollutant concentrations. Concentrations of each organic pollutant class were within similar ranges reported in other studies of urban runoff, however comparison was limited for several of the pollutants given information scarcity. Consistently among PCBs, PBDEs, and PAHs, the more hydrophobic congeners were transported in larger proportions during storm flows relative to low flows. Loads for Water Years 2007-2010 were estimated using regression with turbidity during the monitored months and a flow weighted mean concentration for unmonitored dry season months. More than 91% of the loads for every pollutant measured were transported during storm events, along with 87% of the total discharge. While this dataset fills an important local data gap for highly urban watersheds of San Francisco Bay, the methods, the uniqueness of the analyte list, and the resulting interpretations have applicability for managing pollutant loads in urban watersheds in other parts of the world.

Pollution profiles and risk assessment of PBDEs and phenolic brominated flame retardants in water environments within a typical electronic waste dismantling region

The aim of this study was to assess the pollution profiles of various typical brominated flame retardants in water and surface sediment near a typical electronic waste dismantling region in southern China. We found that polybrominated diphenyl ethers (PBDEs), 2,4,6-tribromophenol (TBP), pentabromophenol (PeBP), tetrabromobisphenol A (TBBPA), and bisphenol A (BPA) were ubiquitous in the water and sediment samples collected in the study region. In water, Σ19PBDEs (sum of all 20 PBDE congeners studied except BDE-209, which was below the detection limit) levels ranged from 0.31 to 8.9 × 10(2) ng L(-1). TBP, PeBP, TBBPA, and BPA concentrations in the water samples ranged from not being detectable (nd-under the detection limit) to 3.2 × 10(2) (TBP), from nd to 37 (PeBP), from nd to 9.2 × 10(2) (TBBPA) and from nd-8.6 × 10(2) ng L(-1) (BPA). In sediment, Σ19PBDEs ranged from nd to 5.6 × 10(3) ng g(-1), while BDE-209 was the predominant congener, with a range of nd to 3.5 × 10(3) ng g(-1). Tri- to hepta-BDE concentrations were significantly (p < 0.01) correlated with each other, except for BDE-71 and BDE-183, and octa- to nona-BDEs concentrations were significantly (p < 0.05) correlated with each other, except for BDE-208. BDE-209 was not significantly correlated with tri- to nona-BDEs. Risk assessments indicated that the water and sediment across the sampling sites posed no estrogenic risk. However, different eco-toxicity risk degrees at three trophic levels did exist at most sampling sites.

The occurrence and distribution of antibiotics in Lake Chaohu, China: seasonal variation, potential source and risk assessment

The distribution and seasonal variation of fifteen antibiotics belonging to three classes (sulfonamides, fluoroquinolones and tetracyclines) were investigated in Lake Chaohu, China. The concentrations of the selected antibiotics in the surface water, eight major inflowing rivers and sewage treatment plant (STP) samples were analyzed by UPLC-MS/MS. The results indicated that sulfamethoxazole and ofloxacin were the predominant antibiotics, with maximum concentrations of 95.6 and 383.4ngL(-1), respectively, in the river samples. In Lake Chaohu, the western inflowing rivers (the Nanfei and Shiwuli Rivers) were the primary import routes for the antibiotics, and the domestic effluent from four STPs were considered the primary source of the antibiotics. The level of antibiotics in Lake Chaohu clearly varied with seasonal changes, and the highest detectable frequencies and mean concentrations were found during the winter. The quality of water downstream of Lake Chaohu was influenced by the lake, and the results of risk assessment of the antibiotics on aquatic organisms suggested that sulfamethoxazole, ofloxacin, ciprofloxacin and enrofloxacin in the surface water of Lake Chaohu and inflowing rivers might pose a high risk to algae and plants.

Effect of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on sexual behaviors and reproductive function in male zebrafish (Danio rerio)

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are ubiquitous in various environmental matrices and organisms and pose a threat to reproductive systems of organisms. However, few studies have explored the effects of PBDEs on sexual and reproductive behaviors in animals. Here we evaluated the effect of BDE-47 exposure on sexual and reproductive behaviors in zebrafish (Danio rerio).

METHODS

We used a charge-coupled device camera to evaluate 3 standard male zebrafish sexual behaviors—chasing, female association and induced female spawning—and assessed effects on reproductive success in female zebrafish that mated with exposed males.

RESULTS

After 21-day BDE-47 exposure, the frequency and total time of males associating with females was dose-dependently decreased. With the highest BDE-47 exposure, 1000 µg/L, the frequency of inducing spawning was decreased. Sexual behaviors and spawning outcome were closely associated in both control and exposure groups. Logistic regression analysis revealed BDE-47 exposure and total time of female association as the main factors contributing to induced female spawning behaviors, which affected final egg production. Multiple stepwise regression analysis suggested that female association and induced spawning by males were associated with egg production. Meanwhile, fecundity was lower for BDE-47-treated groups than controls, with only a significant difference with the highest dose. BDE-47 exposure at 100 and 1000 µg/L in males decreased fertilization rate, but BDE47 had no effect on hatching rate.

CONCLUSIONS

Exposure to BDE-47 may affect sexual behavior and reproductive output in zebrafish.