50 research outputs found

    TOXICOLOGICAL EVALUATION OF REALISTIC EMISSIONS OF SOURCE AEROSOLS (TERESA): APPLICATION TO POWER PLANT-DERIVED PM2.5

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    Determining the health impacts of different sources and components of fine particulate matter (PM2.5) is an important scientific goal, because PM is a complex mixture of both inorganic and organic constituents that likely differ in their potential to cause adverse health outcomes. The TERESA (Toxicological Evaluation of Realistic Emissions of Source Aerosols) study focused on two PM sources - coal-fired power plants and mobile sources - and sought to investigate the toxicological effects of exposure to realistic emissions from these sources. The DOE-EPRI Cooperative Agreement covered the performance and analysis of field experiments at three power plants. The mobile source component consisted of experiments conducted at a traffic tunnel in Boston; these activities were funded through the Harvard-EPA Particulate Matter Research Center and will be reported separately in the peer-reviewed literature. TERESA attempted to delineate health effects of primary particles, secondary (aged) particles, and mixtures of these with common atmospheric constituents. The study involved withdrawal of emissions directly from power plant stacks, followed by aging and atmospheric transformation of emissions in a mobile laboratory in a manner that simulated downwind power plant plume processing. Secondary organic aerosol (SOA) derived from the biogenic volatile organic compound {alpha}-pinene was added in some experiments, and in others ammonia was added to neutralize strong acidity. Specifically, four scenarios were studied at each plant: primary particles (P); secondary (oxidized) particles (PO); oxidized particles + secondary organic aerosol (SOA) (POS); and oxidized and neutralized particles + SOA (PONS). Extensive exposure characterization was carried out, including gas-phase and particulate species. Male Sprague Dawley rats were exposed for 6 hours to filtered air or different atmospheric mixtures. Toxicological endpoints included (1) breathing pattern; (2) bronchoalveolar lavage (BAL) fluid cytology and biochemistry; (3) blood cytology; (4) in vivo oxidative stress in heart and lung tissue; and (5) heart and lung histopathology. In addition, at one plant, cardiac arrhythmias and heart rate variability (HRV) were evaluated in a rat model of myocardial infarction. Statistical analyses included analyses of variance (ANOVA) to determine differences between exposed and control animals in response to different scenario/plant combinations; univariate analyses to link individual scenario components to responses; and multivariate analyses (Random Forest analyses) to evaluate component effects in a multipollutant setting. Results from the power plant studies indicated some biological responses to some plant/scenario combinations. A number of significant breathing pattern changes were observed; however, significant clinical changes such as specific irritant effects were not readily apparent, and effects tended to be isolated changes in certain respiratory parameters. Some individual exposure scenario components appeared to be more strongly and consistently related to respiratory parameter changes; however, the specific scenario investigated remained a better predictor of response than individual components of that scenario. Bronchoalveolar lavage indicated some changes in cellularity of BAL fluid in response to the POS and PONS scenarios; these responses were considered toxicologically mild in magnitude. No changes in blood cytology were observed at any plant or scenario. Lung oxidative stress was increased with the POS scenario at one plant, and cardiac oxidative stress was increased with the PONS scenario also at one plant, suggesting limited oxidative stress in response to power plant emissions with added atmospheric constituents. There were some mild histological findings in lung tissue in response to the P and PONS scenarios. Finally, the MI model experiments indicated that premature ventricular beat frequency was increased at the plant studied, while no changes in heart rate, HRV, or electrocardiographic intervals were observed. Overall, the TERESA results should be interpreted as indicating toxicologically mild adverse responses to some scenarios. The varied responses among the three plants indicate heterogeneity in emissions. Ongoing studies using the TERESA approach to evaluate the toxicity of traffic-related pollution will yield valuable data for comparative toxicity assessment and will give us a better understanding of the contribution of different sources to the morbidity and mortality associated with exposure to air pollution

    PM2.5-induced cardiovascular dysregulation in rats is associated with elemental carbon and temperature-resolved carbon subfractions

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    Abstract Background We tested the hypothesis that cardiovascular responses to PM2.5 exposure will be enhanced in hypertensive rats and linked to specific carbonaceous pollutants in an urban industrial setting. Methods Spontaneously hypertensive rats were exposed by inhalation to concentrated PM2.5 in an industrial area of Dearborn, Michigan, for four consecutive summer days. Blood pressure (BP), heart rate (HR) and HR variability (HRV) metrics (SDNN, RMSSD) were assessed by radiotelemetry and compared to 1 h- and 8 h-averaged fluctuations in PM2.5 composition, with a focus on elemental and organic carbon (EC and OC, respectively), and temperature-resolved subfractions (EC1-EC5, PC (pyrolized carbon), and OC1-OC4), as well as other major and minor PM components. Results Mean HR and BP were increased, while HRV was decreased over 4 days of exposure. Using 1 h averages, EC (1 μg/m3 increase) was associated with increased HR of 11-32 bpm (4-11% increase), 1.2-1.5 ms (22-27%) decreases in SDNN, 3-14 mmHg (1.5-8%) increases in systolic BP, and 5-12 mmHg (4-9%) increases in diastolic BP. By comparison, associations with OC were negligible. Using 8 h averages, EC subfractions were linked with increased heart rate (EC1: 13 bpm; EC2, EC3, PC:  > EC2 > EC3, EC4, PC), but with decreased RMSSD (EC2, EC5 > EC3, EC4). Minimal effects were associated with OC and OC1. Associations between carbon subfractions and BP were negligible. Associations with non-carbonaceous components and trace elements were generally non-significant or of negligible effect size. Conclusions These findings are the first to describe associations between acute cardiovascular responses and thermally resolved carbon subfractions. We report that cardiovascular responses to PM2.5 carbonaceous materials appear to be driven by EC and its EC1 fraction.http://deepblue.lib.umich.edu/bitstream/2027.42/115867/1/12989_2014_Article_306.pd

    Scenario planning for transport practitioners

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    Scenario planning helps in contemplating how the future may develop and can be especially important when needing to make sense of uncertainty – something now pertinent to the transport sector. Accordingly, scenario planning is moving from the periphery of strategic transport planning towards becoming a more normalised and integral contribution. By examining rather than ignoring a range of uncertainties about the future, scenarios can be developed that enable an exploration of different futures, in turn improving transport planning. Scenarios can be narrative based, represented quantitatively, or combine ‘storytelling and number crunching’. Both the process of creating them and of representing the scenarios, deepen an appreciation of uncertainty about the future. In turn this allows planners and policymakers to better understand potential outcomes and challenges and determine how to address these. Scenarios can also be used to identify and assess candidate measures for influencing the transport system, testing these against a range of uncertain future conditions. This helps to identify measures that together can help form a strategy that is more robust. Drawing upon the combined experience of its authors, this paper provides insights into the development of scenarios and their use to improve decision making in transport planning. It offers advice on how to help ensure the scenario development process is credible, how to produce a coherent set of scenarios and how to ensure they are used to engage key stakeholders and to enable policymakers to confidently develop their strategic thinking and plans

    Tungsten-niobium oxide bronzes: a bulk and surface structural study

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    [EN] Materials from the WO3-Nb2O5 system, presenting bronze-type crystal structures, display outstanding functional properties for several applications as thermoelectric materials, lithium-ion battery electrodes, or catalysts. In this work, a series of W-Nb-O oxide bronzes have been synthesized by the hydrothermal method (with Nb/(W + Nb) ratios in the range of 0-1). A combination of bulk and surface characterisation techniques has been applied to get further insights into: (i) the effect of thermal treatments on as-prepared materials and (ii) the surface chemical nature of W-Nb-O oxide bronzes. Thermal treatments promote the following structural changes: (i) loss of emerging long-range order and (ii) the elimination of NH4+ and H2O species from the structural channels of the as-synthesized materials. It has been observed that W-Nb-O bronzes with Nb at% of ca. 50% are able to retain a long-range order after heat-treatments, which is attributed to the presence of a Cs-0.5[W2.5Nb2.5O14]-type structure. Increasing amounts of Nb 5T in the materials (i) promote a phase transition to pseudocrystalline phases ordered along the c-axis; (ii) stabilize surface W s. species (elucidated by XPS); and (iii) increase the proportion of surface Lewis acid sites (as determined by the FTIR of adsorbed CO). Results suggest that pseudocrystalline oxides (with a Nb at% >= 50%) are closely related to NbO2 pentagonal bipyramid-containing structures. The stabilisation of Lewis acid sites on these pseudocrystalline materials leads to a higher yield of heavy compounds, at the expense of acrolein formation, in the gas-phase dehydration of glycerol.The authors would like to acknowledge the Ministerio de Ciencia, Innovacion y Universidades in Spain for the financial support (RTI2018-099668-B-C21 and SEV-2016-0683 projects), and the Electron Microscopy Service at Universitat Politecnica de Valencia for providing facilities and technical support. D. D. also thanks Severo Ochoa Excellence Program for his fellowship (SVP-2014-068669).Delgado-Muñoz, D.; Concepción Heydorn, P.; Trunschke, A.; López Nieto, JM. (2020). Tungsten-niobium oxide bronzes: a bulk and surface structural study. Dalton Transactions. 49(38):13282-13293. https://doi.org/10.1039/d0dt02058cS13282132934938D. J. M. Bevan and P.Hagenmuller , Non-Stoichiometric Compounds , Pergamon , 1973Quan, H., Gao, Y., & Wang, W. (2020). 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    Potential Occupational Exposures and Health Risks Associated with Biomass-Based Power Generation

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    Biomass is increasingly being used for power generation; however, assessment of potential occupational health and safety (OH&amp;S) concerns related to usage of biomass fuels in combustion-based generation remains limited. We reviewed the available literature on known and potential OH&amp;S issues associated with biomass-based fuel usage for electricity generation at the utility scale. We considered three potential exposure scenarios—pre-combustion exposure to material associated with the fuel, exposure to combustion products, and post-combustion exposure to ash and residues. Testing of dust, fungal and bacterial levels at two power stations was also undertaken. Results indicated that dust concentrations within biomass plants can be extremely variable, with peak levels in some areas exceeding occupational exposure limits for wood dust and general inhalable dust. Fungal spore types, identified as common environmental species, were higher than in outdoor air. Our review suggests that pre-combustion risks, including bioaerosols and biogenic organics, should be considered further. Combustion and post-combustion risks appear similar to current fossil-based combustion. In light of limited available information, additional studies at power plants utilizing a variety of technologies and biomass fuels are recommended

    Application of semipermeable membrane devices (SPMDs) to the monitoring of kraft mill effluents with emphasis on potential fish-tainting compound

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    The use of Semipermeable Membrane Devices (SPMDs) for monitoring pulp mill effluents containing potential fish tainting compounds was investigated. SPMDs are lipidfilled polyethylene bags which appear to mimic bioconcentration phenomena in aquatic organisms. They have been used as in situ, passive monitors of organic contaminants such as polynuclear aromatic hydrocarbons (PAHs) in aqueous environments, and were used here in a pulp mill setting. Preliminary method development work included investigating the effect of tubing segment location within the roll of polyethylene on uptake of 2,2’ ,5 ,5 ‘-tetrachlorobiphenyl (TCB), a reference compound. Tubing segment location was determined to have no significant effect on degree of uptake. In addition, polyethylene consistency was investigated by subjecting tubing to various batch solvent extraction conditions. Selected tubing extracts were also analyzed by gas chromatography/mass spectrometry (GCIMS), and the contaminating compounds were identified. Hexane exposures showed that a 24 hour hexane extraction with no solvent replacement was sufficient for the adequate removal of contaminating compounds associated with the polyethylene tubing. Three model compounds were chosen on the basis of their significant presence in kraft mill effluent as well as their potential propensity to taint fish. Octanol-water partition coefficients (KowS) were determined for the compounds, alpha-pinene, guaiacol and dehydroabietic acid, and for 2,2’ ,5 ,5 ‘-TCB. Compound uptake into SPMDs and dialytic recoveries from SPMDs were determined. Generally, the model compounds were not sequestered efficiently by SPMDs, and their dialytic recoveries were low. The behaviour of the compounds was explained on the basis of their KowS, polarities, volatilities and water solubilities. SPMDs were exposed to both untreated and biotreated full-strength unbleached kraft mill wastewater under static conditions. In addition, SPMD exposures were carried out using several concentrations of treated effluent in continuous flow systems. In both types of exposures, SPMDs were found to sequester many compounds, as evidenced by gas chromatograms. Of particular interest was the uptake of compounds which may be responsible for the tainting of eulachons (Thaleichthys pacWcus) in the Kitimat River, B.C. Eulachons are small smelts with a high lipid content which traditionally have been consumed by the Haisla Indians living in the area, but have not been used in this capacity since the early 1970s due to a noticeable off-flavour. Five compounds identified in tainted eulachon were identified in SPMD dialysates after GC/MS analysis. Based on the results shown in this research, SPMDs appear to show significant promise as passive monitors for the detection and possible quantification of tainting compounds in aqueous environments. Their specificity for nonpolar compounds may diminish their usefulness in pulp mill settings, where ionic and polar compounds such as resin acids and phenols are common constituents of wastewaters.Applied Science, Faculty ofCivil Engineering, Department ofGraduat
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