Polychlorinated biphenyls in vegetable soils from Changchun,Northeast China: Concentrations,distribution, sources and human health risks

To investigate the occurrences of polychlorinated biphenyls (PCBs) in suburban vegetable soils of Changchun area, Northeast China, 106 urban vegetable soil samples were collected from Changchun City, Nongan County, Dehui City, Yushu City, Jiutai City, Shuangyang District. We analyzed the concentrations, compositions and sources of 7 PCBs in top soils of Changchun area, and evaluated the non-carcinogenic and carcinogenic risk of PCBs pollution to exposed population. The total concentrations of 7 PCBs ranged from 1.31 to 148 ng/g dry weight (dw) with a mean value of 42.0 ng/g and dominated by Hepta-CBs and Penta-CBs. Principal component analysis (PCA) revealed that PCB pollution in soils of Changchun area mainly related to transportation, vehicle emissions, paints and other industries. Human health risk assessment showed that the cumulative non-carcinogenic and the cumulative carcinogenic risk in children and adults in the industrial land and residential land were acceptable, considering only 7 PCBs homologues were analyzed in this study, the actual risk could be higher.     

Ecotoxicological Risk Assessment of Polychlorinated Biphenyls (PCBs) in Bank Sediments from along the Yamuna River in Delhi,India

The River Yamuna originates from the Yamunotri glacier of the Himalayas and travels 22 km in the Delhi region. The river is used for various purposes in Delhi including drinking water supply. Twenty-eight polychlorinated biphenyls (PCBs) congeners were measured in bank sediments along the river, and their ecotoxicological risk was evaluated. Concentrations of ∑28PCBs varied from 0.20–21.16 ng g^?1 (dry wt.) with mean and median values of 6.63 ng g^?1 and 5.84 ng g^?1 (±0.69 ng g^?1), respectively. The concentration of 12 dl-PCBs concentrations varied from 0.04–2.86 ng g^?1 with a mean of 1.04 ± 0.11 ng g^?1, and their toxic equivalency ranged between <0.01–28.67 pg WHO-TEQ g^?1 with a mean of 10.77 ± 1.06 pg WHO-TEQ g^?1. CB-37, CB-44, CB-114, and CB-118 congeners were dominant among all PCBs congeners. The tri-PCBs (49%) were the main contributors to the PCB homolog followed by tetra-PCBs (35%), and penta-PCB (14%). Because there are no environmental guidelines in India for PCBs in river and marine sediments, concentrations of PCBs and their toxic equivalents were compared in a screening-level assessment with established freshwater sediment quality guidelines and found lower than those guideline values, which suggests no adverse ecotoxicological effect.     

Ecological Risk Assessment of Sediments in Sydney Harbour,Nova Scotia,Canada

Contamination within sediments of Sydney Harbour (once a major industrial port) were evaluated using a multiple lines-of-evidence (LOE) ecological risk assessment (ERA) approach prior to divestiture of the harbor. The multiple LOE approach included: (1) measurement of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals, metalloids, petroleum hydrocarbons(PHCs), and total organic carbon (TOC) concentrations in surface sediments from multiple Sydney Harbour locations; (2) identification and application of sediment quality guidelines (SQGs) from various jurisdictions; (3) comparisons of harbor sediment chemistry against background/reference sediment chemistry; (4) determining number and frequency of exceedances over SQGs; (5) calculating mean probable effect level-quotients (PEL-Qs); (6) PAH forensic source evaluation; (7) review of previous sediment chemistry and biota tissue data; and (8) characterizing benthic habitat at harbor stations. The ERA determined that current sediments exhibited mostly low probability of adverse effects. Furthermore, contaminated sediments exhibiting a high probability of adverse effects were localized to only a few stations within the harbor. Ongoing natural recovery of harbor sediments is likely responsible for attenuating contaminants that historically were higher than those measured in this study and were previously distributed over much wider areas of the harbor. Results suggest that legacy industrial activities and current urban sewage effluents are the major sources of contamination in Sydney Harbour sediments.     

利用雨养泥炭沼泽及湖泊沉积物重建多氯联苯污染时空变化趋势

为了重建不同历史时期多氯联苯(PCBs)的沉降速率以研究其污染的时空变化趋势,本研究分析了PCBs在泥炭芯和湖泊沉积柱芯中浓度和沉降速率的变化规律,并评估了泥炭芯和湖泊沉积柱芯用于PCBs沉降变化研究的适用性.对采集柱芯进行定年分析发现,泥炭沼泽可以很好地记录PCBs历史沉降变化,并且泥炭中的PCBs没有出现降解情况,...     

Isolation and Characterization of Acidic Peptides in Soy Sauce

A soy sauce sample was fractionated by gel filtration on a Sephadex G–15 column, then the fractions were subfractionated on the basis of acidity by ion exchange chromatography on a QAE-Sephadex A–25 column. The acidic subfractions with various acidities were further fractionated, using a preparative amino acid analyzer and by paper chromatography to separate the acidic peptide components.

Four dipeptides and sugar derivatives of ten dipeptides and two tripeptides were isolated and characterized as the major acidic peptides in soy sauce. However, it was difficult to anticipate any direct contribution of these peptides to the flavor construction in soy sauce on the basis of their contents and taste intensities.     

Seasonal-spatial distributions,congener profile,and risk assessment of polychlorinated biphenyls (PCBS) in the surficial sediments from the coastal area of Bangladesh

A comprehensive congener specific assessment of polychlorinated biphenyls (PCBs) was conducted for the first time in Bangladesh. All 209 PCB congeners in the surficial coastal sediments from the coastal areas of Bangladesh were analyzed by GC-MS/MS. The total concentrations of PCBs (∑PCBs) varied from 5.27 to 92.21 and 4.61 to 105.3 ng/g dw in winter and summer, respectively, and the ranges were comparable to or higher than those recorded in the sediments from the coastal areas of India, Korea, China, and Taiwan. The seasonal difference in the levels of PCBs was not statistically significant (p > 0.05). The spatial distribution revealed that the areas with recent urbanization and industrialization (Chittagong, Cox’s Bazar and Sundarbans) were more contaminated with PCBs than the unindustrialized area (Meghna Estuary). Moderately chlorinated (4–6 Cl) homologs dominated PCB profiles. A set of congeners based on their detection frequencies and abundance were identified and categorized as potential environmental marker PCBs, which can be used for the future selective monitoring studies where there would be limitations on whole congener assessment. Ecotoxicologically, the sedimentary PCB concentrations exceeded some of the existing environmental quality standards, suggesting a potential threat to the aquatic organisms in the Bangladeshi coastal areas.     

Potential for phytoremediation of polychlorinated biphenyl-(PCB-)contaminated soil

Weathered soils contaminated with commercial-grade Aroclor 1260 from three sites in Canada were used to investigate the polychlorinated biphenyl (PCB) phytoextraction potential of nine plant species (Festuca arundinacea, Glycine max, Medicago sativa, Phalaris arundinacea, Lolium multiflorum, Carex normalis, and three varieties of Cucurbita pepo ssp. pepo) under controlled greenhouse conditions. The soils used varied in PCB concentration (90-4200 microg/g) and total organic content (0.06-2.02%). Greenhouse experiments controlled for PCB volatilization through the use of a vented enclosure and by isolating the contaminated soils with parafilm. After 8 wks, PCB concentrations of 47-6700 microg/g were observed in root tissues. Although PCB concentrations in shoot tissues were lower (< 1-470 microg/g), the absolute amounts of PCBs observed in shoot tissue were significant (1.7-290 microg) once shoot biomass was accounted for. Congener signatures indicated that tetra- to hexa-chlorobiphenyls contributed the largest proportions to shoot tissues, but hepta-to nona-chorobiphenyls were also present in measurable amounts. Overall, the results indicate that varieties of C. pepo were more effective at extracting PCBs from soil than other plants screened The evidence suggests that this was mainly due to root uptake of PCBs and tranlocation to the shoots, rather than volatilization of PCBs from soil. All plants screened showed signs of stress in the most highly contaminated soil (4200 microg/g), but not in the two lower PCB contaminated soils (250 and 90 microg/g, respectively). No detectable decreases in soil PCB concentrations were observed in these short-term greenhouse experiments, but the results suggest that this may be achievable through multiple plantings.     

Toxicity Reference Values for the Toxic Effects of Polychlorinated Biphenyls to Aquatic Mammals

Threshold tissue residue concentrations of polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) were derived from the published results of semi-field (i.e., field collected food items were used as a medium of exposure to PCBs in laboratory reared animals) or field toxicity studies conducted with seals, European otters and mink. Based on biomagnification factors (BMFs) and concentrations of PCBs or TEQs measured in fish fed in the diet of experimental aquatic mammals, dietary threshold concentrations were estimated. Hepatic vitamin A, thyroid hormone concentration, suppression of natural killer (NK) cell activity and proliferative response of lymphocytes to mitogens were the toxicity endpoints measured in aquatic mammals. Threshold concentrations for PCBs or TEQs in livers of aquatic mammals to elicit the physiological effects ranged from 6.6 to 11?µg PCBs/g (geometric mean: 8.7?µ/g) and 160 to 1400?pg TEQs/g (geometric mean: 520?pg/g), lipid weight, respectively. The BMFs for PCBs and TEQs varied depending on the marine mammal species, and therefore the dietary threshold concentrations could be referred only by a range of values (rather than a mean value), which were 10 to 150?ng PCBs/g and 1.4 to 1.9?pg TEQs/g, wet weight, for PCBs and TEQs, respectively.     

Challenges in Defining Background Levels for Human and Ecological Risk Assessments

A robust approach to defining, understanding, and tracking contaminant levels is crucial to human and ecological risk evaluation and risk management. Whether materials are present in the environment naturally (mercury, radon, nitrogen, phosphorous) and enhanced by human activities or are man-made (DDT and PCBs), the complexity of contaminant distributions and sources requires careful design and implementation of studies to characterize background. Before collection or analyses of data are initiated, an explicit definition of background appropriate to specific risk assessments is needed. Problems associated with determining background levels of contaminants in fish and seafood illustrate some challenges faced by risk assessors. Major differences in estimates of background may result from differences in sampling and analytical methods including selection of sampling locations, approaches to data analysis and synthesis, and tissues selected for analysis. Different approaches may yield background exposure or risk estimates that differ by 50% or more. Methodological transparency is essential in data collection and analysis to establish background and to ensure that data are used appropriately in both human and ecological risk assessments.     

Colonization and growth of dehalorespiring biofilms on carbonaceous sorptive amendments

Removal of polychlorinated biphenyls (PCBs) from contaminated sediments is a priority due to accumulation in the food chain. Recent success with reduction of PCB bioavailability due to adsorption onto activated carbon led to the recognition of in situ treatment as a remediation approach. In this study, reduced bioavailability and subsequent break-down of PCBs in dehalorespiring biofilms was investigated using Dehalobium chlorocoercia DF1. DF1 formed a patchy biofilm ranging in thickness from 3.9 to 6.7?µm (average 4.6?±?0.87?µm), while the biofilm coverage varied from 5.5% (sand) to 20.2% (activated carbon), indicating a preference for sorptive materials. Quantification of DF1 biofilm bacteria showed 1.2–15.3?×?10⁹ bacteria per gram of material. After 22?days, coal activated carbon, bone biochar, polyoxymethylene, and sand microcosms had dechlorinated 73%, 93%, 100%, and 83%, respectively. These results show that a biofilm-based inoculum for bioaugmentation of PCBs in sediment can be an efficient approach.     

Bioremediation of Aroclor 1242 by a consortium culture in marine sediment microcosm

Plant terpenes have proven to be effective in stimulation of polychlorinated biphenyls (PCBs) biodegradation in soil systems. However, data on the application of plant terpenes in marine sediments contaminated with PCBs remains limited. The aim of this study was to ascertain the roles of a PCB degrading consortium and plant terpenes in stimulation of PCB biodegradation in marine sediments. The consortium culture 1-2Mix (strains 1-2M and 1-2T in commensalism), a utilizer of biphenyl and a natural substrate was enriched and isolated from marine sediments from the Busan coast, South Korea. PCB degradation by this culture was shown to be more effectively induced by tangerine peel extract than other known substrates (limonene, pinene, and cymene). Coastal sediment microcosms inoculated with 1-2Mix were set up to elucidate the effect of the consortium and plant terpenes on degradation of Aroclor 1242. After four weeks, the highest removal rates of PCBs, compared with the control (autoclaved sediment and no inoculation of 1-2Mix), were observed in order of the inducers tested; biphenyl (71.1%), tangerine peel extract (69.5%), surfactant (66.0%), and limonene (63.0%). Bioaugmentation effect was doubled in the presence of natural substrates such as tangerine peel extract and limonene, indicating effectiveness of these substrates in biostimulation. It was concluded that the tangerine peel extract could replace biphenyl as a feasible induction substrate for effective remediation of PCBs in the marine sediment.     

Evolutionary and Ecological Effects of Multi-Generational Exposures to Anthropogenic Stressors

Biological and ecological responses to stress are dictated by duration and frequency, as well as instantaneous magnitude. Conditional compensatory responses at the physiological and behavioral levels, referred to as ‘acclimation’, may mitigate effects on individuals experiencing brief or infrequent periods of moderate stress. However, even modest stress over extended periods may reduce the fitness of some or all exposed individuals. In this way, specific stress that persists over multiple generations will increase probabilities for extinction of populations composed of sensitive individuals. For populations whose members demonstrate variance and heritability for stressor response, this selective loss of sensitive individuals may result in populations dominated by resistant individuals. The formation of these ‘adapted’ populations may be considered an ecological compensatory mechanism to multi-generational stress. Paradoxically, the biological costs to individuals of toxicity and physiological acclimation may result in obvious signs of stress in affected wildlife populations while the costs of genetic adaptation may be more covert. It is important to consider such costs because recent evidence suggests that anthropogenic stressors have acted as powerful selection agents that have modified the composition of wildlife populations subjected for successive generational exposures to specific stressors. This essay focuses on a case study where adaptation has been demonstrated in fish populations with a history of chronic exposure to persistent, bioaccumulative and toxic environmental contaminants. Because the magnitude, breadth and long-term outcomes of such changes are unknown, ecological risk assessments that are limited in focus to short-term exposures and consequences may seriously underestimate the ecological and evolutionary impacts of anthropogenic stressors.     

Distributions and Congener Patterns of PCBs in Fish from Major Aquaculture Areas in the Pearl River Delta,South China

The distribution and concentrations of polychlorinated biphenyls (PCBs) were determined in surface sediments and fish collected from freshwater fishponds in six major aquaculture areas of the Pearl River Delta. The concentrations of total PCBs ranged from 7.32 to 36.2 ng/g (dry weight) in sediments and 5.15 to 226 ng/g (lipid weight) in five species of fish, with higher concentrations in fishponds from two industrialized areas. Feeding habits of fishes played a significant role on the accumulation of PCBs and their homologue patterns in fish tissues, with higher concentrations in muscle and viscera of mandarin fish (Siniperca kneri), and tilapia (Tilapia mossambica) and lower in grass carp (Ctenopharyngodon idellus). In muscle, IUPAC No. 118, 138, 81/87, 153, 180, 52, 49, 99, and 44 congeners were the most dominant out of the 36 congeners measured in the present study. The contents of PCBs in fish cultivated in the Pearl River Delta were rather low when compared with the maximum concentration of total PCBs of 2.0 μg/g (wet weight), imposed by the U.S. Food and Drug Administration edible seafood. However, due to the bioaccumulation and biomagnification nature of PCBs through the food chain, continuous monitoring of PCBs as well as other Persistent Organic Pollutants in this rapidly developed region is encouraged.     

Synthetic Chemicals with Potential for Natural Attenuation

Natural attenuation of petroleum hydrocarbons is predictable and self-sustaining because bacteria able to use the contaminants as growth substrates are widely distributed. In contrast, bacteria able to grow at the expense of chlorinated aliphatic compounds are less common and the natural attenuation of such compounds is, therefore, less predictable. The purpose of this paper is to describe examples of other synthetic organic compounds that are known to be biodegradable and have the potential for natural attenuation in the field.     

Field Studies Using European Starlings to Establish Causality between PCB Exposure and Reproductive Effects

Accumulation and effects of polychlorinated biphenyls (PCBs) in avian species were evaluated at a Superfund site located at Crab Orchard National Wildlife Refuge, Illinois, and seven criteria were used to assess whether there was a causal relationship between PCB exposure and observed reproductive effects. European starlings (Sturnus vulgaris) were monitored at nest boxes constructed at each of two exposed and two reference sites. During the breeding season, starling productivity (number of chicks produced per nest) and adult nest attentiveness behavior (provisioning behavior) were monitored. At 15 days post-hatch, chicks were collected for contaminant and biomarker analyses. Chicks were necropsied, ethoxyresorufin-O-deethylase (EROD) activity measured in liver tissue, and PCB (Aroclor 1254) and 34 chlorinated biphenyl (CB) congener concentrations measured in carcasses using gas chromatography. PCB and CB concentrations also were measured in eggs that failed to hatch. Mean Aroclor 1254 and quantified CB concentrations were greater (P<0.001) in eggs that failed to hatch and 15-day-old chicks collected from PCB sites compared to those collected from reference sites. EROD activity was greater (P=0.005) in 15-day-old chicks collected from PCB sites and was correlated with carcass PCB concentrations. Reduced adult nest attentiveness behavior and decreased chick survival were observed at PCB sites. Six of the seven causal criteria evaluated provided evidence that observed reproductive effects resulted from exposure to PCBs. Using this weight-of-evidence approach provided a means for establishing the likely cause of effects and thus provided managers with information needed in decision-making processes.     

Evaluation of Three Measures of Exposure Concentration: A Case Study of Surface Sediment Concentrations in the Passaic River

Arithmetic and lognormal means historically have been used as estimates of exposure concentration for both human health and ecological risk assessment. Past risk assessment guidance has emphasized the need to include all available informa tion, particularly regarding the spatial and temporal aspects of data and exposure. One estimate of exposure concentration that includes spatial information is the 95% upper confidence limit (UCL) of the area weighted mean. An area weighted mean is calculated using weightings based on the ratio of the area associated with a sample location and the total area of the study area. Currently, U.S. Environmental Protection Agency (USEPA) risk assessment guidance recommends the use of the 95% UCL of the arithmetic mean as the most appropriate measure of exposure concentration for soil and sediment in human health and ecological risk assess ments. The purpose of this study was two fold: (1) to evaluate the use of the 95% UCL of the area weighted mean vs. the 95% UCL of the arithmetic mean for the lognormal distribution and the normal distribution using a large data set from a recent riverine sediment characterization study, and (2) to evaluate the potential associated with the different approaches for reduction in surface sediment exposure concentrations for 2,3,7,8 TCDD and coplanar polychlorinated biphenyls (PCBs) for several subsets of the data. The results of this evaluation indicated that there was no significant reduction in exposure concentrations of the study area surface sediments after any of the selected higher concentration data points had been removed from the various data subsets. In addition, this evaluation indicated that, due to its dependence on the variance of the data, the 95% UCL of the arithmetic mean for a lognormal distribution produced subset exposure concentrations that were higher than the calculated concentrations of the full data set and produced the smallest percent changes in concentration compared to the other two measures. Based on this analysis, the 95% UCL of the area weighted mean was determined to be the most stable and appropriate estimator of exposure concentration for surface sediments.     

Determinants of Serum PCBs in Adolescents and Adults: Regression Tree Analysis and Linear Regression Analysis

Regression tree analysis, a non-parametric method, was undertaken to identify predictors of the serum concentration of polychlorinated biphenyls (sum of marker PCB ¹ ABBREVIATIONS: BMI: body-mass index, CV: cross validation, ln: natural logarithm, ns: not significant, PCAHs: polychlorinated aromatic hydrocarbons, PCBs: polychlorinated biphenyls, R² _a: adjusted coefficient of determination, VIF: variance inflation factor. View all notes 138, 153, and 180) in humans. This method was applied on biomonitoring data of the Flemish Environment and Health study (2002–2006) and included 1679 adolescents and 1583 adults. Potential predictor variables were collected via a self-administered questionnaire, assessing information on lifestyle, food intake, use of tobacco and alcohol, residence history, health, education, hobbies, and occupation. Relevant predictors of human PCB exposure were identified with regression tree analysis using ln-transformed sum of PCBs, separately in adolescents and adults. The obtained results were compared with those from a standard linear regression approach. The results of the non-parametric analysis confirm the selection of the covariates in the multiple regression models. In both analyses, blood fat, gender, age, body-mass index (BMI) or change in bodyweight, former breast-feeding, and a number of nutritional factors were identified as statistically significant predictors in the serum PCB concentration, either in adolescents, in adults or in both. Regression trees can be used as an explorative analysis in combination with multiple linear regression models, where relationships between the determinants and the biomarkers can be quantified.     

First Evidence for Homologous Recombination-mediated Large DNA Inversion on the Bacillus subtilis 168 Chromosome

A Bacillus subtilis 168 strain carrying an inversion of about 1600kb-long chromosomal DNA was isolated. Physical and genetic analyses demonstrated that the inversion was generated as a result of homologous recombination between two homologous sequences integrated at the met and leuB loci. This is the first clear evidence of a large stable chromosomal inversion induced by homologous recombination in B. subtilis.     

Coupling of bioaugmentation and phytoremediation to improve PCBs removal from a transformer oil-contaminated soil

This study was carried out to assess the dissipation of 17 selected polychlorinated biphenyl (PCB_i) congeners in a transformer oil-contaminated soil using bioaugmentation with 2 PCB-degrading bacterial strains, i.e., Pseudomonas spp. S5 and Alcaligenes faecalis, assisted or not by the maize (Zea mays L.) plantation. After 5 and 10 weeks of treatment, the remaining concentrations of the target PCB_i congeners in the soil were extracted and measured using GC-MS. Results showed that the bacterial augmentation treatments with Pseudomonas spp. S5 and A. faecalis led to 21.4% and 20.4% reduction in the total concentration of the target PCBs (ΣPCB_i), respectively, compared to non-bioaugmented unplanted control soil. The ΣPCB_i decreased by 35.8% in the non-bioaugmented planted soil compared with the control. The greatest degradation of the PCB congeners was observed over a 10-week period in the soil inoculated with Pseudomonas spp. S5 and cultivated with maize. Under this treatment, the ΣPCB_i decreased from 357 to 119 ng g^?1 (66.7% lower) and from 1091 to 520 ng g^?1 (52.3% lower). Overall, the results suggested that the combined application of phytoremediation and bioaugmentation was an effective technique to remove PCBs and remediate transformer oil-contaminated soils.