High-Molecular-Weight Polycyclic Aromatic Hydrocarbons in the Area and Vicinity of the Deza Chemical Plant,Czech Republic

Polycyclic aromatic hydrocarbons (PAHs) with molecular weight exceeding 278 amu were analyzed in air, water, and soils from the area and vicinity of the DEZA Chemical Plant (Vala w ské Mezi q í ) í, Czech Republic). Air and water were sampled using semipermeable membrane devices (SPMDs); grab sampling was applied for soils. Laser desorption/ionization-time-of-flight mass spectrometry (LDI-TOF MS) and liquid chromatography/ion trap mass spectrometry with atmospheric pressure chemical ionization (LC/APCI-ITMS) were employed for the quick assessment of PAH distribution and for the identification and quantification of some high-molecular-weight PAHs. Compounds with molecular mass up to 450 u were found. LDI-TOF mass spectra and selected LC/APCI-ITMS profiles (m/z 303, m/z 327, and m/z 351) were compared to identify potential source of contamination in this locality. High-molecular-weight PAHs were found in all environmental compartments in the area studied; their levels were quite high close to their source and decreased sharply with increasing distance from it.     

POLYCYCLIC AROMATIC HYDROCARBON CONCENTRATIONS OF AIRBORNE PARTICLES IN URBAN AIR OVER THE PAST TWENTY YEARS

To estimate human exposure to hazardous chemicals, it is important to measure the annual trends regarding the concentrations of these compounds in the environment. Airborne particulate samples were collected over the past 20 years (1980–2001) from ambient air using a quartz fiber filter with the help of a high-volume air sampler placed on the top of the National Institute of the Public Health building, Minato-ku, Tokyo, Japan. In the present study, portions of these filter samples were analyzed to investigate the trends regarding the concentration of PAHs in urban air over the sampling period. The concentrations of various PAHs per unit air volume were determined. The concentrations of seven PAHs decreased within the sampling periods, especially in the late 1980s, and slowly decreased from the middle 1990s. The concentrations of seven PAHs were higher in autumn and winter than in the spring and summer.     

Evaluation of a Denuder-MOUDI-PUF Sampling System to Measure the Size Distribution of Semi-Volatile Polycyclic Aromatic Hydrocarbons in the Atmosphere

This study describes a field comparison conducted between 2 methods employing different MOUDI impactor configurations to evaluate their performance in sampling and measurement of the size distribution of 15 priority pollutant polycyclic aromatic hydrocarbons (PAHs). Samples were collected during 24 h periods approximately every 7th day, beginning at 8:00 AM, in 2 different sites of the Los Angeles Basin. One site was near Central Los Angeles in an area impacted by high vehicular traffic, whereas the other site was located about 60 km downwind of central Los Angeles (receptor site). Particle samples from about 43 m 3 of air were collected using collocated MOUDI impactors and classified in 3 aerodynamic diameter size intervals: 0-0.18 w m (ultrafine mode I), 0.18-2.5 w m (accumulation mode II), and 2.5-10 w m (coarse mode III). One MOUDI operated in the conventional mode, the other with a vapor trapping system that included an XAD-4 coated annular denuder placed upstream of the impactor and a polyurethane foam plug (PUF) placed in series behind the impactor. PAHs were separated and quantified by HPLC with fluorescence detection optimized for the highest sensitivity. The results showed that for both sites, using either sampling system, the size distributions obtained are similar for the less volatile PAHs (log [ p ° L ] h m 3.2), but different for the more volatile PAHs (log [ p ° L ] S m 2.06). In the central Los Angeles site, the largest PAH fraction was found in the 0-0.18 w m (mode I) size range, typical of primary emissions. At the downwind location, the largest fraction was in the 0.18-2.5 w m (mode II) size range, consistent with an "aged" aerosol. At both sites, albeit not statistically significant, the mean regular to denuded MOUDI mass ratios were 33-36% and 11-19% higher, respectively, for the more volatile and the less volatile PAH groups. Sampling with the regular MOUDI configuration is simpler and thus recommended for measurement of the size distribution of PAHs in either group.     

Gas/Particle Partition Measurements of PAH at Hazelrigg,U.K.

During September and October, 1998, the new Integrated Organic Gas and Particle Sampler (IOGAPS), was operated at Hazelrigg, UK, the field measurement station of the University of Lancaster. Gas/particle partition ratios of twenty-two 2–5 ring PAH were determined using both the IOGAPS (in which the gas phase is collected before the particle phase) and a low flow sampler which utilized the traditional filter-sorbent geometry. For compounds of intermediate volatility, less partitioning to the gas phase was observed when the denuder was used. The denuder (8- channel, 60 cm, 16.7 L min^?1 air sampling rate) trapped small amounts of several non-volatile PAH. This result is consistent with particle diffusion losses of 5 to 10% for particles less than 0.05 μm under the flow conditions in the denuder. The 60-cm denuder was probably longer than necessary for the flow rate used. During the sampling, both glass fiber and Teflon-coated glass fiber filters were used. Without a denuder in front of a glass fiber filter, the fine particulate mass (PM 2.5) measurements showed a major positive bias that has been attributed to adsorption of gases by the filter. Teflon-coated glass fiber filters were not subject to this artifact problem, and equal masses were collected on filters from the denuded and non-denuded air flows.     

Numerical simulation of temperature and concentration distributions in fluidized beds with liquid injection

In this paper a numerical simulation study of dynamic behavior of a fluidized bed with liquid injection is presented. A continuum model has been developed taking into account the mass and energy balances of solid, gas as well as liquid to describe the temperature and concentration distributions in gas-solid-fluidized beds. The model considers the deposition efficiency of the liquid droplets as well as the influence of the spray nozzle region. For solving the non-linear partial differential equations with discrete boundary conditions a finite element method is used. Numerical computations have been done with two different schemes of time integration, a fully implicit and a semi implicit scheme. The complex correlations of mass and liquid flow rates, mass and heat transfer, drying, and transient two-dimensional air humidity, air temperature, particle wetting, liquid film temperature and particle temperature were simulated. The model was validated with transient measurements of the air temperature and air humidity at the outlet of a fluidized bed with water injection.     

Levels of Volatile Polycyclic Aromatic Hydrocarbons in the Atmosphere of Athens,Greece

Eight light polycyclic aromatic hydrocarbons (PAHs) have been measured in the gas and particle phase of the atmosphere of Athens, in one site during an eight-month period (December, 1997-July, 1998). A glass fiber filter-polyurethane foam sheet high volume air sampler was used to collect the particle and vapor phase of the eight PAHs in nineteen samples, taken from the Athens center. Methodology of sampling as well as levels and abundance of PAHs in both phases are discussed. Seasonal variation of very volatile PAHs was found not to be strictly related to high temperatures and explanations are proposed. An unexpected PAHs pattern from two summer photochemical episodes is also discussed.     

Characterization of Gaseous and Particulate Polycyclic Aromatic Hydrocarbons in Ambient Air of Delhi,India

Three seasonal sampling campaigns were undertaken at an urban site of Delhi for collection of PAHs in particulate and gas phase. Sampling was done by using modified Respirable Dust (PM ≤10μm) sampler attached with polyurethane foam (PUF) plugs and compared with conventional Respirable Dust (PM ≤10 μm) sampler. Total 16 EPA PAH (gaseous + particulate) were determined by Gas Chromatograph-Mass Spectrophotometer (GC-MS). The 3-ring PAH constitutes approximately 90% of the gaseous PAHs with phenanthrene, fluoranthene, acenapthylene, and acenaphthene being the most abundant gaseous PAHs. PAHs with 4- to 6- rings accounted for 92%, 87% and 78% in samples collected during winter, summer and monsoon season respectively. Gaseous PAHs, particulate PAHs and total PAHs were higher during winter as compared to summer and monsoon seasons. The contribution of particulate PAHs were 1.4, 2.1, and 2.5 times higher in winter, summer and monsoon, respectively than of gaseous PAHs. Indeno[123-cd]pyrene, benzo[ghi]perylene, dibenzo[ah]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene and chrysene were found to be the most abundant PAH compounds in the particulate PAHs during all the seasons. The result from application of diagnostic ratio suggests that the higher particulate PAHs emissions were predominantly associated with vehicular emissions along with emissions from biomass burning during winter season.     

High-Volume Aerosol Filtration and Mitigation of Inertial Particle Rebound

The performance of electrostatically charged blown microfiber filter media was characterized for high-volume sampling applications. Pressure drop and aerosol collection efficiency were measured at air pressures of 55.2 and 88.7 kilopascals (kPa) and filter face velocities ranging from 2.5 to 11.25 meters per second (m/s). Particle penetration was significant for particles above 0.5 micrometers (μm) in aerodynamic diameter where the onset of particle rebound was observed as low as 200 nanometers (nm). Particle retention was enhanced by treating filters in an aqueous solution of glycerol. Adding this retention agent eliminated electrostatic capture mechanisms but mitigated inertial rebound. Untreated filters had higher nanoparticle collection efficiencies at lower filter face velocities where electrostatic capture was still significant. At higher filter face velocities, nanoparticle collection efficiencies were higher for treated filters where inertial capture was dominant and particle rebound was mitigated. Significant improvements to microparticle collection efficiency were observed for treated filters at all air flow conditions. At high air pressure, filter efficiency was greater than 95% for particles less than 5 μm. At low air pressure, performance enhancements were not as significant since air velocities were significantly higher through the fiber mat. Measured single fiber efficiencies were normalized by the theoretical single fiber efficiency to calculate adhesion probability. The small fiber diameter (1.77 μm) of this particular filter gave large Stokes numbers and interception parameters forcing the single fiber efficiency to its maximum theoretical value. The adhesion probability was plotted as a function of the ratio of Stokes and interception parameter similar to the works of others. Single fiber efficiencies for inertial nanoparticle collection were compared to existing theories and correlations.

Copyright 2014 American Association for Aerosol Research     

Design and Test of 2.5 μ m Cutoff Size Inlet Based on a Particle Cup Impactor Configuration

Based on the particle cup impactor configuration, an inlet for sampling fine particles smaller than 2.5 w m in diameter was designed for operation at a flow rate of 25 l/min. To determine the optimal dimensions of the particle cup impactor applicable to the PM 2.5 inlet, calibration experiments were carried out at wind velocities of 2 and 24 km/h in a wind tunnel. It was noted that the particle cup impactor having an impaction nozzle diameter of 3.2 mm and the nozzle-to-cup spacing of 3.6 mm yielded a sharp size cutoff. Supplementary experiments were conducted on sampling performance with the inlet having the optimally selected configuration at a near-zero wind speed in the test chamber. Results of the tests showed the inlet had a cutoff size of 2.43 w m in aerodynamic diameter, at 25 l/min, and that particles larger than 2.5 w m were trapped in the cup. Additional experiments covering a flow rate between 10 and 40 l/min with particle sizes between 0.8 and 4.3 w m were conducted in the test chamber. A field test was performed to examine the PM 2.5 inlet in real situations. The performance indicated that the inlet design met the basic requirements of fine-particle sampling.     

大气中多环芳烃衍生物的研究进展

多环芳烃衍生物是一类已被证实比多环芳烃具有更强"三致作用"(致癌、致畸和致基因突变)的环境污染物,它广泛存在于环境介质特别是大气颗粒物中。本文就其来源、分布、采样方式、样品前处理、分离分析方法等方面综述了近年来大气颗粒物中多环芳烃衍生物的的研究进展。     

Large Particle Size Distribution in Five U.S. Cities and the Effect on a New Ambient Participate Matter Standard (PM10)

A mobile aerosol-sampling system was used to determine the large particle ambient aerosol size distribution (up to approximately 100 μm particle diameter) in five cities across the United States: Birmingham, Alabama; Research Triangle Park, North Carolina; Philadelphia, Pennsylvania; Phoenix, Arizona; and Riverside, California. A mobile wide range aerosol classifier (WRAC) developed at the University of Florida was used. The study shows that any measurement of ambient particulate matter with a size-fractionating inlet sampler will be influenced by the ambient particle size distribution.

Mass distribution measurements determined by the WRAC were compared with mass measurements obtained simultaneously using TSP Hi-Vol and 15 μm cut-size inhalable particulate network samplers. Aerosol size-classification results showed the presence of a large particle mass mode at all sites sampled. The position and magnitude of the large particle mode varied and was not a simple function of concentration. The percentage of the total aerosol mass collected by the present EPA reference method high-volume air sampler varied from about 85 to 95%. The percentage of total aerosol mass less than 10 μm varied from about 50 to 90%, depending on the sampling location and sampling condition.     

Toward an Optimization of the Backwashing Process in the Flexible Fiber Filter

Abstract

Backwashing process was used to recover the retention capacity of a deep bed filter. A field scale fiber filter was operated with an in‐line injection of a coagulant for the treatment of natural surface water (Nak‐dong River in Korea). A mass balance of SS could be made thus allowing a direct estimation of the effectiveness of the backwashing process. The purpose of this paper was to study the influence of two parameters of backwashing (air injection and number of backwashing stages) on its effectiveness. The backwashing efficiency was estimated through the initial pressure drop after the backwash, the effluent quality, the duration of the filtration time between two successive backwashes, and the detached mass of retained suspended solids. Conditions could be found for removing 99% of the retained SS. As a general conclusion, the effectiveness of backwashing mainly depended upon air injection. The duration of air injection and the number of sequences were the most important factors related to the efficiency of backwashing.     

DBD等离子体改性芳纶表面的动态工艺研究

采用介质阻挡放电(DBD)空气等离子体,选择不同放电强度及处理时间对芳纶表面进行连续动态处理。通过扫描电镜以及光电子能谱仪对处理前后芳纶表面进行表征。结果表明,经DBD等离子体处理后的芳纶表面粗糙度有较大提高,浸润性显著提高,且纤维表面C元素质量分数下降超过5%,0元素质量分数约上升8%;芳纶表面的粗糙度、浸润性及含氧基团含量均随放电强度和处理时间的增加而提高。     

A laboratory method for the assessment of polycyclic aromatic compound emission from heated bitumen

A laboratory-based generation and collection system for bitumen fumes is presented. The method has been evaluated with respect to sampling temperature, sampling time and the mass of bitumen used for the fume generation. Fume emissions from different bitumens were compared and the dependence on temperature was studied in the laboratory. Clean-up of the bitumens and the fume condensates was carried out using dimethylformamide liquid-liquid extraction and an h.p.l.c. back-flush technique. More than 180 polycyclic aromatic compounds (PACs) in the range of three to five benzene rings could be detected, consisting of both polynuclear aromatic hydrocarbons (PAHs) and polynuclear aromatic sulphur heterocyclics (PASHs). For both compound groups, the abundance of polymethylated derivatives was higher than that of the parent compounds.     

Potential for the formation of respirable fibers in carbon fiber reinforced plastic materials after combustion

Fundamental aspects for the thermal decomposition and formation of respirable fragments of carbon fibers are investigated to assess the health hazard of carbon fiber reinforced plastic material after a fire. The influence of temperature (600°C‐900°C)/heat flux (30‐80 kW/m²), time of thermal load (up to 20 minutes), and oxygen exposure is analyzed by means of mass loss and fiber diameter of intermediate modulus and high tenacity fibers with initial diameters of 5 to 7 μm. Various types and concentrations of flame retardants were tested with respect to fiber protection. Epoxy‐based composite specimens (RTM6/G0939) additionally containing aluminum or magnesium hydroxide and/or zinc borate (1‐25 wt% per resin) were analyzed by cone calorimetry. Carbon fiber decomposition increases with combustion/irradiation time and temperature/heat flux, after a threshold temperature (ca 600°C) is exceeded. Critical fiber diameters below 3 μm are reached within minutes and are predominantly observed close to the panel surface in contact with air. Effective fiber protection is achieved by flame retardants acting beyond 600°C, forming thermally resistant layers such as zinc borate. A new field of research is opened identifying flame retardants, which protect carbon fibers in carbon fiber reinforced plastic.     

Study on airflow field and fiber motion with new melt blowing die

In this study, a new melt‐blowing die was studied with the computational fluid dynamic approach. A bead‐viscoelastic element fiber model was established to model three‐dimensional paths of the fiber motion with the standard linear solid (SLS) constitutive equation in different airflow fields. The effects of this newly designed die on the velocity field, temperature field, and turbulence fluctuation field at the centerline were studied and compared with the traditional melt blowing die. The fiber motion was simulated and compared with the airflow field of different dies. The simulations results demonstrated that the new die was able to reduce the velocity fluctuations of the air flow near the outlet of the polymer capillary and generate the higher centerline air velocity and temperature. The fiber attenuation and motion were related to the centerline air velocity, temperature, and turbulent fluctuation in the melt blowing process. POLYM. ENG. SCI., 59:1182–1189 2019. © 2019 Society of Plastics Engineers     

Distribution and Sources of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from the Northern Part of the Persian Gulf (Hormuzgan Province)

Sediments from the intertidal areas of Hormuzgan province in northern part of Persian Gulf (Iran) were investigated for the levels and possible sources of 15 polycyclic aromatic hydrocarbons (PAHs). Samples of sediments were collected from twelve sampling sites and analyzed for PAHs by gas chromatography–mass spectrometry (GC-MS). The results showed that the total concentrations of PAHs ranged from 765 to 1898 ng/g dry weight. Composition pattern in the sediment samples from 12 sampling sites was dominated by 4-ring PAH compounds. Molecular indices based on ratios of PAH concentrations were used to differentiate PAHs from pyrolitic, petrogenic and mixed origins. The results of study suggested that the main sources of PAHs in the sediment were mixed with pyrolitic and petrogenic inputs. According to the US sediments quality guidelines (SQGs) (ERL/ERM) sediments of the mentioned region did not show any ecotoxicological risk for benthic organisms.     

The Exposure Profiles,Correlation Factors and Comparison of PAHs and Nitro-PAHs in Urban and Non-Urban Regions in Suspended Particulate Matter in Poland

ABSTRACT

Polycyclic aromatic hydrocarbons (PAHs) and their nitrated derivatives are responsible for mutagenic activation of ambient air. The aim of the study was the assessment of exposure for PAHs and nitro-PAHs in the urbanized region in Poland in comparison with the non-urbanized region and assessment of seasonal variation of PAHs and nitro-PAHs. Concentrations of 12 PAHs, 8 nitrated PAHs in total suspended particulate matter in air of urban and suburban (reference samples-mountain region) region in Poland during four seasons have been shown. The method of solvent extraction of particulate matter, fractionation organic extract and HPLC and GC/MS analysis were applied. The concentrations of PAHs and nitro-PAHs were 10–100 times lower in reference samples than concentrations of PAHs and nitro-PAHs in urban region in summer. The concentrations of PAHs and nitro-PAHs were highest in winter. The exposure profiles of PAHs and nitro-PAHs in four seasons have been shown. The correlation factor between concentrations of PAHs and nitro-PAHs was found. Important influence of ambient air temperature for PAHs and nitro-PAHs concentrations was shown. Obtained results suggest that the coal combustion in Polish households was the main source of PAHs and their nitro derivatives contaminations. Emission from transport sources is a secondary source of air pollution in urban areas.     

Light Degrading Properties of Size-Fractionated PM 10 Aerosol Samples Collected from an Industrial Area in Brisbane,Australia

Thirty-seven days of PM 10 aerosol samples (particles with aerodynamic diameter <10 w m) were collected in an industrial area in Brisbane during April to June 1999 to study the light extinction efficiencies of urban aerosols in different size ranges. The light scattering coefficient of the air was measured by nephelometry. The light absorption coefficient of the aerosol samples was measured by the integrating plate laser absorption method. Multiple linear regression techniques were used to investigate the relationships between the visibility degrading properties and the chemical composition of the aerosol samples. The results are comparable with those from other visual air quality studies. The absorption of light by fine (PM 2.5 ) aerosols is mainly due to elemental carbon (EC) particles smaller than 0.5 w m. The b 0 ap values of EC particles in different size ranges are 9.08 (< 2.7 w m) and 0.32 (2.7-10 w m)m 2 g -1 , respectively. The absorption of light by coarse (PM 2.5-10 ) aerosols is mainly due to soil ( b 0 ap = 0.17) and organic ( b 0 ap = 1.11) particles. The scattering of light is highly related to the concentration of fine particles in the air (mass scattering efficiency b 0 sp = 1.65) and is mainly due to the fine sulphate ( b 0 sp = 10.9), soil ( b 0 sp = 2.73), and EC ( b 0 sp = 3.89) particles. On average, fine EC (44%), sulphate (20%) and soil (7%) particles, NO 2 (9%), and Rayleigh scattering (19%) were the largest contributors of visibility degradation for the sampling days in this study.     

Processing of poly(ethersulfone)/graphite fiber composites: Thermooxidation,rheology, and consolidation

This study relates the formability of thermoplastic poly(ethersulfone) HTA composites to thermooxidative history and rehological behavior. HTA/IM8 graphite fiber performs were prepared under various temperature, time, and environmental (unbagged and vacuum-bagged) conditions, then consolidated into finished laminates under identical conditions. X-ray photoelectron spectroscopy and pyrolysis/gas chromatography/mass spectrometry were used to assess chemical degradation, and dynamic mechanical analysis (DMA) was used to evaluate T_g and rheological behavior in the finished laminates. All performing conditions resulted in some degradation of the HTA matrix, the presence of air being especially detrimental. The nature of this degradation is discussed and related to changes in T_g., melt viscosity of the matrix resin, and the extent of consolidation. A new DMA approach to evaluating degree of consolidation is developed and shown to offer considerable promise for quantitative assessment and ranking of composites.