[Pollution Characteristics and Multilevel Risk Assessments of Antibiotics in the Urban Rivers of Beijing, China].

To comprehensively assess the pollution characteristics and ecological risks of antibiotics in the rivers in Beijing, the concentrations of 35 common antibiotics belonging to four categories were quantified by using solid phase extraction combined with high-performance liquid chromatography-tandem mass spectrometry. The ecological risks of antibiotics were evaluated using the methods of risk quotient (RQ) and joint probability curves (JPCs). The results showed that a total of 33 antibiotics were detected in the surface water of ten rivers in Beijing, and the total concentrations of antibiotics ranged from N.D. to 1 573.57 ng·L-1. Sulfamethoxazole showed the highest concentration (N.D.-160.04 ng·L-1), followed by sulfadiazine (0.09-147.90 ng·L-1) and ofloxacin (0.28-94.72 ng·L-1). There were 16 antibiotics with a detection frequency greater than 50.0 %. The RQ method showed that there were 12 antibiotics with potential ecological risks. Tetracycline, clarithromycin, and trimethoprim showed the highest risks, with RQs of 3.99, 1.86, and 1.01, respectively. The risks of antibiotics at the outlets of wastewater treatment plants were higher than those in mainstream rivers. The PNEC exceedance rates of tetracycline, clarithromycin, and trimethoprim were above 2.3 %. Based on JPCs, the maximum risk product of clarithromycin was 1.66 %, and it showed low risks to 0.3 %-7.0 % of species. The risks of other antibiotics could be ignored. The detection frequency, distribution of concentrations, most sensitive species, and species sensitivity distribution of antibiotics had important impacts on the ecological risk assessment. Using the multilevel ecological risk assessment strategy can effectively avoid inadequate protection and overprotection and is also conducive to the hierarchical and zoning management of antibiotics throughout the region.

[Pollution Level and Risk Assessment of OPEs in Typical River Basins of China].

Organophosphate esters(OPEs), as a substitute for brominated flame retardants, are widely used in production and life, and their environmental pollution and toxic effects have attracted widespread attention. In this study, the concentrations and distribution characteristics of OPEs in seven major drainage basins of China were sorted out. The average daily dose of OPEs in Chinese adults, adolescents, and children was calculated to assess the health risks, and the reliability of the results was evaluated using Monte Carlo simulation. The toxic effect concentrations of 12 OPEs on aquatic organisms were investigated, and the species sensitivity distribution(SSD) curve was constructed to assess the ecological risk. The results showed that the 5th percentile concentration of ΣOPEs in the seven drainage basins was 52.61 ng·L-1 under the low exposure scenario. The median concentration of ΣOPEs in the seven basins was 499.74 ng·L-1, with trichloroethyl phosphate(TCEP), triethyl phosphate(TEP), and triethyl phosphate(1,3-dichloro-2-propyl) esters(TDCP) as the main contaminants. Under the high exposure scenario, the 95th percentile concentration of ΣOPEs in the seven basins was 1904.4 ng·L-1, 3.8 times that of the intermediate exposure scenario, and the Yangtze River Basin had the highest ΣOPEs concentration under the high exposure scenario. The health risk assessment showed that the non-carcinogenic risk of OPEs exposure through drinking water was within acceptable limits for different populations. Trimethyl phosphate(TMP), triisobutyl phosphate(TiBP), and TCEP were the main contributors to cancer risk. The results of ecological risk assessment showed that TCEP had medium ecological risk at the high exposure level, tributyl phosphate(TnBP) had medium ecological risk under the intermediate exposure scenario, and there was higher ecological risk under the high exposure scenario. Triphenyl phosphate(TPhP) had a risk quotient greater than 1 under the low, intermediate, and high exposure scenarios, and there was a high ecological risk, which requires special attention.

[Occurrence Distribution and Risk Assessment of Organophosphate Esters in A Typical Area of the Estuary in the Yellow River Basin].

As a type of emerging pollutant, organophosphate esters (OPEs) have the characteristics of toxicity, persistence, and bioaccumulation. Due to their wide use in production and life, OPEs pose potential risks to ecosystems when they enter the environment. In this study, the concentrations of 14 species of OPEs in surface water were determined using UPLC-MS/MS, and the spatial distribution of the OPEs in the surface water of the estuary of the Yellow River basin was further analyzed. The pollution sources were analyzed using correlation analysis and principal component analysis, and the ecological risk was evaluated. The results indicated that the concentration of Σ14OPEs in surface water ranged from 183.81 to 1674.52 ng·L-1, with an average concentration of 638.25 ng·L-1. Tris(2-chloroethyl) phosphate (TCEP) and tris(1-chloro-2-propanyl) phosphate (TCPP) were the main OPEs. The Xiaoqing River flowing through the urban area differed from the main stream of the Yellow River and other branches in terms of OPEs composition characteristics, which showed a greater impact from human activities. The distribution of Σ14OPEs showed an obvious regional pattern, with a trend of increasing and then decreasing along the direction of the Yellow River inlet. The results of source analysis revealed that human activities such as industrial wastewater discharge from different industries, transportation, and atmospheric deposition were the sources of OPEs in surface water. The ecological risk assessment results indicated that TCEP posed a high risk to aquatic organisms in the main stream of the Yellow River, Xiaoqing River, and Zhimai River, and tri-n-butyl phosphate (TnBP) and triphenyl phosphate (TPhP) posed a low risk at some sites.

Mechanical Force-Induced Blue-Shifted and Enhanced Emission for AIEgens.

Mechanochromic (MC) luminescence of organic molecules has been emerging as a promising smart material for optical recording and memory devices. At the same time, pressure-induced blue-shifted and enhanced luminescence are rarely reported now. Herein, a series of cyanostilbene-based AIEgens with different substituents were synthesized to evaluate the influence of morphology transformation and push-pull electronic effect on the MC luminescence. Among these luminophores, compound 1 with one cyano group and diethylamino group was more susceptible to mechanical stimuli and obtained blue-shifted and enhanced fluorescence in response to anisotropic grinding. Powder X-ray diffraction patterns indicated that the MC behaviors were ascribed to the solid-state morphology transition from crystal-to-crystal. Analysis of crystal structures revealed that loose molecular packing is a key factor for high high-contrast MC luminescence. The smart molecular design, together with the excellent performance, verified that luminophores with twisted structures are ideal candidates for MC luminogens.

[Comparison of Health Risk from Sources of Perfluoroalkyl Substances in Taihu Lake for Different Years].

Pollution characteristics and spatial distributions of perfluoroalkyl substances (PFASs) in surface water samples were investigated in Taihu Lake in 2010 and 2019, respectively. A hybrid model based on the positive matrix factorization (PMF) and the health risk assessment model were employed for quantifying the contributions of sources to PFASs concentrations and the source risks. The method contained two stages:1 the sources of PFASs were apportioned using the PMF model, and 2 the contribution of health risks from each source was quantitively estimated. Three factors (source categories) were extracted using PMF, including:coating industry sources, textile and electroplating sources, and fluoride-processing industry sources. Their contributions to PFASs concentration were 29.59%, 25.68%, and 44.72% for 2010 and 67.69%, 10.26%, 22.05%, for 2019, respectively. The health risk of PFASs in the water assessed by the health risk assessment (HRA) model was 4.56E-07 for 2010 and 2.69E-07 for 2019, which was lower than 1E-06. The source contributions to health risks estimated by the PMF-HRA hybrid model were:64.86% (2010) and 92.48% (2019) for textile and electroplating sources, 31.30% (2010) and 5.04% (2019) for coating industry sources, and 3.84% (2010) and 2.48% (2019) for fluoride-processing industry sources. For the two years, the concentrations of PFOA and PFOS were reduced significantly, indicating the effective control of their emissions during the past ten years in Taihu Lake. However, it was also shown that the concentrations of PFBS and PFHxS were increased. These findings suggest that the above short chain-PFCs species should be the focus for further control and management, and their health risks should be studied in future research.

[Pollution Characteristics and Risk Assessment of Organophosphate Esters in Rivers and Water Body Around Taihu Lake].

To explore the pollution characteristics, potential sources, and ecological and health risk of organophosphate eaters (OPEs) in the surface water of Taihu Lake, water samples from 18 surrounding rivers were collected, as well as 11 water samples from Taihu Lake. The concentrations of 13 OPEs in the water were determined using UPLC-MS/MS, and the spatial distribution of the OPEs in surface water of Taihu Lake basin was further analyzed. The results indicate that, in addition to tripropyl phosphate (TPrP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tricresyl phosphate (TCrP), ten OPEs were detected in all the water samples, the total concentration (ΣOPEs) ranged from 152.5 ng·L-1 to 2524 ng·L-1, and the concentration median value was 519.2 ng·L-1. Tri(chloropropyl) phosphate (TCPP) and tri(2-chloroethyl) phosphate (TCEP) were the dominant OPEs, with the concentration ranges of 73.7-1753.9 ng·L-1 (medium value:204.6 ng·L-1) and 43.9-313.5 ng·L-1 (medium value:131.3 ng·L-1), respectively. The ΣOPEs decreased from the northwest region to the southeast, which corresponds to the economic and industrial development. The results of the source identification reveal that the wastewater discharge from electronics and textile enterprises, construction materials, and vehicular and marine traffic emissions may be the principal sources of the OPEs in Taihu Lake. The ecological risk assessment results indicate that only TCPP, tri(dichloropropyl) phosphate (TDCP), and triphenyl phosphate (TPhP) in some sites had a low risk. The health risk assessment reveals that there were no risks based on water intake, but the long-term risk of OPEs to the aquatic ecosystem and surrounding residents still need attention.

[Organ-Specific Accumulation and Toxicokinetics of Ephedrine in Adult Zebrafish (Danio rerio)].

Ephedrine (EPH) is an alkaloid commonly used to relieve nasal congestion caused by colds, allergic rhinitis, rhinitis, and sinusitis, and to control bronchial asthma. It is also be used as a raw material in the manufacture of methamphetamine. Although the distribution of EPH in surface waters has been widely studied, its uptake, internal distribution, and toxicokinetic processing in exposed organisms have not been well investigated. In this study, we investigated the uptake, disposition, and toxicokinetics of EPH in zebrafish (Danio rerio) in a semi-static exposure system. EPH was consistently detected in zebrafish biological samples, with the highest concentrations of 84.97 ng·g-1 detected in the brain tissue of fish in the high treatment group. Over the 14-d exposure period, the relative abundance of mean concentrations of EPH in biological samples generally followed the order of brain > ovary > liver > intestine > muscle. The uptake rate constants (Ku), elimination rate constants (Ke), and half-lives of EPH in the biological tissues were in the ranges 0.23-570.31 L·(kg·d)-1, 1.22-6.11 d-1, and 0.12-0.57 d, respectively. The observed bioconcentration factor (BCFo) and kinetically-derived bioconcentration factor (BCFk) were similar, ranging 0.24-337.33 L·kg-1 and 0.13-316.43 L·kg-1, respectively. These results are helpful for understanding the behavior of psychoactive substances in aquatic organisms and have directive significance for studying their toxicity and ecological risks to aquatic organisms.

[Distribution Characteristics and Source Identification of Organophosphate Esters in Key Waters Areas of Taihu Lake].

Organophosphate esters (OPEs) are ubiquitous in the environment and pose potential risks to ecosystems in that they produce cytotoxicity, genetic toxicity, developmental toxicity, neurotoxicity, and the endocrine disrupting effect. This study aimed to investigate the distribution, sources, and ecological risk of thirteen OPEs in industrial wastewater, influents and effluents of wastewater treatment plants, and the surface waters of key areas (Changzhou City) in Taihu Lake. The results showed that ∑OPEs in industrial wastewater ranged from 91.70-840.52 ng·L-1. The profiles varied from different industries; however, tris (1-chloro-2-propyl) phosphate (TCPP), triethyl phosphate (TEP), and tris (2-chloroethyl) phosphate (TCEP) were the dominant compounds. The ∑OPEs from the wastewater treatment plants were relatively higher, ranging from 1859.59-2778.57 ng·L-1. They are rather resistant to traditional wastewater treatment techniques. The removal rate of ∑OPEs, aryl OPEs, and chlorinated OPEs was 14.97%, 97.91%, and 4.37% (for W1) and 17.32%, 90.83%, and 5.40% (for W2), respectively. The concentration of OPEs in the surface water was in the range of 219.47-689.85 ng·L-1, which was lower than that in wastewater. In addition, TEP, TCPP and TCEP predominated in the surface water samples. A principle component analysis (PCA) indicated that the industrial wastewater, emissions of vehicles, and the release of building materials may be the main sources of OPEs in the study area. A risk quotient was used to assess the ecological risk of OPEs to aquatic organisms in the surface water. Most of the OPEs showed low ecological risk, but 2-ethylhexyl diphenyl phosphate (EHDPP) posed a moderate risk in some sites, and the possible ecological effects caused by the OPEs should not be ignored in the key areas of Taihu Lake.

[Pollution Characteristics and Risk Assessment of Typical Organophosphate Esters in Beijing Municipal Wastewater Treatment Plant and the Receiving Water].

Organophosphate esters (OPEs) are ubiquitous in the environment and pose a potential threat to ecosystems and human health. A method for the determination of eight OPEs by ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) was established. The recovery rates of eight target compounds with different solid-phase extraction columns, different eluents, and different eluent volumes were compared. The results showed that using ENVI-18 column enrichment, OPEs were eluted with 8 mL acetonitrile containing 25% (volume fraction) dichloromethane, and the labeled recovery rate of the target compound was 92.5%-102.2%. The recoveries of different matrix samples were 88.5%-116.1% and relative standard deviation was 1.7%-9.9%. The concentration range of 8 different detectable organophosphate esters in the effluent of sewage treatment plant is 85.9-235.4 ng·L-1 during the six-day sampling process, permissive river downstream of the six-day ΣOPEs average total concentration was 130.3 ng·L-1, higher than the 119.4 ng·L-1 upstream water concentration, but lower than the sewage treatment plant effluent concentration of total 162.5ng·L-1. The study shows that the sewage treatment plant cannot completely remove OPEs; for triethyl phosphate (TEP) and 3 (2-ethyl hexyl) phosphate ester (TEHP) there exists a negative removal phenomenon, whereas for other OPEs the removal rate was between 14.1% and 84.9%, and the total ΣOPEs removal rate by the sewage plant was 50.0%. The TPhP in the effluent of the sewage treatment plant has medium environmental risk (RQ>0.1), and other organophosphates have low environmental risk (RQ<0.1); however, the long-term mixing effects of organophosphate esters on the ecosystem of the receiving river should not be ignored.

A new method to quantify the health risks from sources of perfluoroalkyl substances, combined with positive matrix factorization and risk assessment models.

A hybrid model based on the positive matrix factorization (PMF) model and the health risk assessment model for assessing risks associated with sources of perfluoroalkyl substances (PFASs) in water was established and applied at Dianchi Lake to test its applicability. The new method contains 2 stages: 1) the sources of PFASs were apportioned by the PMF model and 2) the contribution of health risks from each source was calculated by the new hybrid model. Two factors were extracted by PMF, with factor 1 identified as aqueous fire-fighting foams source and factor 2 as fluoropolymer manufacturing and processing and perfluorooctanoic acid production source. The health risk of PFASs in the water assessed by the health risk assessment model was 9.54 × 10-7 a-1 on average, showing no obvious adverse effects to human health. The 2 sources' risks estimated by the new hybrid model ranged from 2.95 × 10-10 to 6.60 × 10-6 a-1 and from 1.64 × 10-7 to 1.62 × 10-6 a-1 , respectively. The new hybrid model can provide useful information on the health risks of PFAS sources, which is helpful for pollution control and environmental management. Environ Toxicol Chem 2018;37:107-115. © 2017 SETAC.

[Distribution Characteristics of Drugs of Abuse and Their Metabolites in Aqueous Environment of Beijing, China].

This work investigated the occurrence and distribution of six drugs of abuse and their metabolites, i.e. methamphetamine(METH), amphetamine(AMP), ketamine(KET), ephedrine(EPH), methcathinone(MC) and hydroxylimine(HY) in the surface water and groundwater in Beijing, China. Forty-three samples were collected and analyzed by solid-phase extraction and high performance liquid chromatography coupled to tandem mass spectrometry(SPE-HPLC-MS/MS). The result showed that KET, MC and HY were not detected in any of the analyzed samples. EPH was the most abundant and ubiquitous compound in the surface water, with the detection frequency of 42% and average concentration of 10.1 ng·L-1, followed by METH(25%, average 1.8 ng·L-1). Only trace amount of AMP was detected in some groundwater samples(n.d.-2.2 ng·L-1), with detection frequency of 21%. Spatial variation of target drug concentrations in the aqueous environment was also studied, and the highest levels of METH and EPH were observed in Liangshui River. Risk assessment suggested that the RQ values of target compounds were lower than 0.10. Although no toxic effects could be expected at the current levels, further studies are needed to assess the long-term effect of drugs of abuse and their metabolites on organisms as well as the joint toxic effect.

[Occurrence, Distribution, and Ecological Risk of Antibiotics in Surface Water in the Liaohe River Basin, China].

The pollution and ecological risk characteristics of five typical antibiotics found in the surface water of the Liaohe River Basin (LRB) were analyzed and evaluated using solid-phase extraction and high-performance liquid chromatography tandem mass spectrometry. These results showed that macrolides have the highest average concentration of all antibiotics in the surface water of the LRB of 201.88 ng·L-1, followed by quinolones, trimethoprim, and sulfonamides with average concentrations of 113.40 ng·L-1, 93.93 ng·L-1, and 124.27 ng·L-1, respectively. Tetracycline demonstrated the lowest concentration at 24.37 ng·L-1. In addition, antibiotics pollution of the Daliao River is clearly identified as being higher than that of the Liaohe River, and the highest proportion of antibiotic pollution (49.1%) is found to come from human use according to a source apportionme0nt analysis. Relatively high levels of ecological risk are identified from Trimethoprim and Erythromycin-H2O concentrations, especially for cities such as Xinmin, Shenyang, and Anshan. The risk assessment indicates that surface water of the LRB faces high ecological risk and argues for greater attention to be paid to risk management and pollution controls.

Sediment PAH source apportionment in the Liaohe River using the ME2 approach: A comparison to the PMF model.

Environmental contaminant source apportionment is essential for pollution management and control. This study analysed surface sediment samples for 16 priority polycyclic aromatic hydrocarbons (PAHs). PAH sources were identified by two receptor models, which included positive matrix factorization (PMF) and multilinear engine 2 (ME2). Three PAH sources in the Liaohe River sediments were identified by PMF, including traffic, coke oven and coal combustion. The ME2 model apportioned one additional source. The two models yielded excellent correlation coefficients between the measured and predicted PAH concentrations. Traffic emission was the primary PAH source associated with the Liaohe River sediments, with estimated PMF contributions of 58% in May and 63% in September. Coke oven (19%-25%) and coal combustion (13%-18%) were the other two major PAH sources. For ME2, gasoline and diesel were separated: accounted for 14% in May and 16% in September; and 53% in May and 48% in September. This study marks the first application of the ME2 model to study sediment contaminant source apportionment. The methodology can potentially be applied to other aquatic environment contaminants.

Source contributions and spatiotemporal characteristics of PAHs in sediments: Using three-way source apportionment approach.

Polycyclic aromatic hydrocarbon (PAHs) were measured in sediments from 29 sites throughout Taihu Lake in China during 2 seasons to investigate spatiotemporal characteristics and source contributions using a 3-way source apportionment approach to positive matrix factorization (PMF3). Seasonal and spatial variations of levels and toxicity suggested higher individual carcinogenic PAH concentrations and toxic equivalent quantity (TEQ) in the flooding season. Three-way PAHs dataset (PAH species, spatial variability, and seasonal variability) was analyzed by PMF3, and its results were compared with a widely used 2-way model (PMF2). Consistent results were observed: vehicular emission was the most important contributor (67.08% by PMF2 and 61.83% by PMF3 for the flooding season; 54.21% by PMF2 and 52.94% by PMF3 for dry season), followed by coal combustion and wood combustion in both seasons. The PMF-cluster analysis was employed to investigate spatial variability of source contributions. Findings can introduce the 3-way approach to apportion sources of PAHs and other persistent organic pollutants (POPs) in sediments, offering the advantage of accounting for information on 3-way datasets.

Bioaccumulation and trophic transfer of perfluorinated compounds in a eutrophic freshwater food web.

In this study, the bioaccumulation of perfluorinated compounds from a food web in Taihu Lake in China was investigated. The organisms included egret bird species, carnivorous fish, omnivorous fish, herbivorous fish, zooplankton, phytoplankton, zoobenthos and white shrimp. Isotope analysis by δ(13)C and δ(15)N indicated that the carnivorous fish and egret were the top predators in the studied web, occupying trophic levels intermediate between 3.66 and 4.61, while plankton was at the lowest trophic level. Perfluorinated carboxylates (PFCAs) with 9-12 carbons were significantly biomagnified, with trophic magnification factors (TMFs) ranging from 2.1 to 3.7. The TMF of perfluorooctane sulfonate (PFOS) (2.9) was generally comparable to or lower than those of the PFCAs in the same food web. All hazard ratio (HR) values reported for PFOS and perfluorooctanoate (PFOA) were less than unity, suggesting that the detected levels would not cause any immediate health effects to the people in Taihu Lake region through the consumption of shrimps and fish.

Historical trends of concentrations, source contributions and toxicities for PAHs in dated sediment cores from five lakes in western China.

In this work, sixteen U.S. EPA priority PAH compounds in the dated sediment cores were detected from five lakes in western China. In most lakes, the concentrations of the total PAHs (ΣPAHs) increased from the deep layers to the surface sediments. Two source categories, i.e. vehicular emission and biomass & domestic coal combustion were identified by Unmix, a factor analysis receptor model to explore the source contributions of PAHs in the dated sediments. The source apportionment results showed that biomass & domestic coal combustion contributed larger proportion of PAHs in the five lakes. The toxicities of PAHs in the dated sediments, assessed by BaP equivalent (BaPE) values showed that the BaPE increased gradually from the deep layers to the surface sediments in most lakes. For the first effort, the contribution of each source to BaPE was apportioned by Unmix-BaPE method, and the result indicated that the vehicular emission posed the highest toxic risk. The percentage contribution of vehicular emission for PAHs and BaPE also increased from the deep layers to the surface sediments, while biomass & domestic coal combustion exhibited the opposite tendency.

Source apportionment of perfluorinated compounds (PFCs) in sediments: using three multivariate factor analysis receptor models.

Understanding the levels, distribution and sources of perfluorinated compounds (PFCs) in sediments is of great significance for the management of aquatic environments. In this work, 26 sediment samples were collected from Dianchi Lake in China and ten PFCs compounds were measured. The concentrations of the total PFCs (∑PFCs) in the sediments ranged from 0.21 to 2.45 ng g(-1)dw (dry weight), with an average value of 0.95 ng g(-1)dw. PFOS was the most abundant compound among the ten PFCs with the average concentration of 0.33 ng g(-1)dw, followed by PFOA at 0.21 ng g(-1)dw. A two-dimensional HCA (hierarchical cluster analysis) heat map was depicted to analyze the spatial variation of individual PFCs compound and the possible origins in the sediments. Two groups were clustered by HCA, showing the possible source categories (PFOS-cluster and PFOA-cluster). Additionally, PCA-MLR, PMF and Unmix models were employed to quantitatively calculate the contribution of extracted sources. Three models concluded consistent results that PFOS-factor and PFOA-factor were the two main source categories for PFCs in the sediments. The contribution percentages were 43% (PCA-MLR), 48% (PMF) and 46% (Unmix) from the former source, and were 54% (PCA-MLR), 43% (PMF) and 44% (Unmix) from the latter source, respectively. The findings and the approaches used in this work can provide useful information for further study of source apportionment for PFCs in sediments and other environmental compartments.

[Qualitative and quantitative detections of pyrethroid pesticides by terahertz time-domain spectroscopy].

Pyrethroids pesticides are broad-spectrum insecticides which were used to control variety of pests, and were mainly used to hygienic insecticides and agricultural pest control. The room-temperature terahertz spectra of b-cypermethrin, 1-cyhalothrin and deltamethrin were investigated by terahertz time-domain spectroscopy (THz-TDS) technology. The three pyrethroids pesticides were easily discriminated according to the absorption spectra within 0.2-2.2 THz. We employed SLR and PLS method to perform the quantitative analysis of the mixture of deltamethrin in polyethylene. The PLS method provides better result than SLR method. The detection limit of deltamethrin content in the mixture can be down to 2.0%, and the maximum value of absolute error was 0.8%. The root mean square error was 0.55%. This result proved that the THz-TDS technique is quite potential for pesticide molecular discrimination and content determination.

Source and risk assessment of PCBs in sediments of Fenhe reservoir and watershed, China.

The concentrations of polychlorinated biphenyls (PCBs) in sediments from the Fenhe reservoir and watershed were detected at 28 sites in wet and dry seasons. The ∑(123)PCBs ranged from n.d. to 126.49 ng g(-1) dw. The dominated congeners were tri-PCBs (34.29%) and tetra-PCBs (24.05%). In the Fenhe reservoir, ∑(123)PCBs presented a decreasing trend, while percentages of low chlorinated congeners showed an increasing trend. For the temporal variations, PCBs homologues profiles of sediment samples and spatial distribution of ∑(123)PCBs for the two periods were similar (with CD = 0.021 and r(2) = 0.999 respectively), although PCBs concentrations in the wet season were significantly higher than in the dry season. PCA was applied to analyze the possible sources for PCBs, suggesting that PCBs might be mainly influenced by Aroclor 1016 and 1242. Compared with 3 established sediment quality guidelines, levels of PCBs in sediments of the investigated watershed might have a potential biological impact, especially in the wet season.