Kinetic studies of O3 reactions with 3-bromopropene and 3-iodopropene in the temperature range 288–328 K

The kinetics of the reactions of O₃ with 3-bromopropene and 3-iodopropene has been studied over the temperature range of 288–328 K at atmospheric pressure. The results obtained for the room temperature rate constants are (1.88 ± 0.22) × 10^?18 and (3.52 ± 0.43) × 10^?18 cm³ molecule^?1 s^?1, and the proposed Arrhenius expressions are k = (3.47 ± 1.28) × 10^?15 exp[(?2233 ± 110)/T] and k = (8.17 ± 2.12) × 10^?14 exp[(?2991 ± 80)/T] cm³ molecule^?1 s^?1 for 3-bromopropene and 3-iodopropene, respectively. The atmospheric chemical lifetimes of these two compounds with O₃ were also estimated from these values.     

Mixing properties of submicrometer aerosol particles in the urban atmosphere—with regard to soot particles

Individual aerosol particles were collected on three days with different meteorological conditions in June 2000 in the urban atmosphere of Tsukuba, Japan. The samples collected with an electrostatic aerosol sampler (EAS) were examined by electron microscopy. The mixing properties of submicrometer aerosol particles of 0.02–0.2 μm radius were studied using the dialysis (extraction) of water-soluble material. Atmospheric aerosol particles were classified into four types with respect to the mixtures of water-soluble and water-insoluble material. The proportions of particles with water-soluble material (hygroscopic particles) ranged from 20% to 80% in the whole radius range and tended to increase with increasing radius. Moreover, by the morphological appearance, soot-containing particles were classified into two types, i.e., externally mixed soot-particles and internally mixed soot-particles. The number fractions of internally mixed soot-particles increased with increasing radius. It is found that the volume fraction of water-soluble material (ε) for the internally mixed soot-particles increased with increasing radius. In a “polluted” case, the sample showed a dominant number fraction (75%) of internally mixed soot-particles in the larger radius range of 0.1–0.2 μm.     

Collection efficiency of a midget impinger for nanoparticles in the range of 3–100 nm

Impingers have been employed for collection of biological particles for a long time and the collection efficiency for submicron particles has been well studied for a few impinger models, like the SKC Biosampler and the AGI 30. These efficiency studies have been limited to particles larger than about 15 nm. The aim of this research is to determine the collection efficiency of ultrafine particles (from 3 to 100 nm) of a 25 ml midget impinger. The effect of different collection parameters (particle type, collection fluid volume and type and flow rate) was studied and results are presented here. All results showed minimum collection efficiencies from 3 to 10% at approximately 40–57 nm. Increasing the volume of the collection liquid and flow rate improved the collection efficiency of the impinger.     

Interaction of nitrogen dioxide (NO2) with a monolayer of oleic acid at the air–water interface – A simple proxy for atmospheric aerosol

The reactions between atmospheric oxidants and organic amphiphiles at the air–water interface of an aerosol droplet may affect the size and critical supersaturation required for cloud droplet formation. We demonstrate that no reaction occurs between gaseous nitrogen dioxide (1000 ppm in air) and a monolayer of an insoluble amphiphile, oleic acid (cis-9-octadecenoic acid), at the air–water interface which removes material from the air–water interface. We present evidence that the NO₂ isomerises the cis-9-octadecenoic (oleic) acid to trans-9-octadecenoic (elaidic) acid. The study presented here is important for future and previous studies of (1) the reaction between the nitrate radical, NO₃, and thin organic films as NO₂ is usually present in high concentrations in these experimental systems and (2) the effect of NO₂ air pollution on the unsaturated fatty acids and lipids found at the air–liquid surface of human lung lining fluid.     

Estimating Future NO2 Levels in the Greater Los Angeles Area by Source–Type Contribution

Two indicator pollutants, carbon monoxide (CO) for mobile source influence and sulfur dioxide (SO₂) for stationary source influence, were used to estimate source-type contributions to ambient NO₂ levels in a base year and to predict NO₂ concentrations in a future year. For a specific source-receptor pair, the so-called influence coefficient of each of three source categories (mobile sources, power plants, and other stationary sources) was determined empirically from concurrent measurements of CO and SO₂ concentrations at the receptor site and CO and SO₂ emissions from each source category in the source area. Those coefficients, which are considered time invariant, were used in conjunction with the base year and future year NO _x emission values to estimate source-type contribution to ambient NO₂ levels at seven study sites selected from the Greater Los Angeles area for both the base year period, 1974 through 1976, and the future goal year of 1987 in which the air quality standards for NO₂ are to be attained. The estimated NO₂ air quality at the seven sites is found to meet the national annual standard of 5 pphm and over 99.9% of total hours, the California 1-hr NO₂ standard of 25 pphm in 1987. The estimated power plant contributions to ambient NO₂ levels are found to be considerably smaller than those to total NO _x emissions in the area. Providing that reasonably complete air quality and emissions data are available, the present analysis method may prove to be a useful tool in evaluating source contributions to both short-term peak and long-term average NO₂ concentrations for use in control strategy development.     

Study of the uncertainty in NO<Subscript>2</Subscript> chemiluminescence measurements due to the NO–O<Subscript>3</Subscript> reaction in sampling lines

Introduction  

The change in light intensity that takes place when an ambient air sample is drawn into the detection chamber of a chemiluminescence monitor generates changes in the concentrations of several species, such as NO₂, NO and O₃. Although this phenomenon has been known for several decades, there is still no commonly accepted approach on when or how to correct for it in NO₂ and O₃ readings.     

Studies of the coarse particle (2.5–10 μm) component in UK urban atmospheres

An analysis is presented of continuous simultaneous measurement data for PM₁₀ and PM_2.5 using TEOM instruments from five sites in the United Kingdom. The results are analysed specifically in relation to the sources and processes influencing the coarse particle fraction (2.5–10 μm). The data show a generally strong correlation between fine and coarse particle concentrations at all sites, with a generally higher proportion of coarse particles in the dryer months of the year. The one rural site shows a notably lower proportion of coarse particles than the urban and suburban sites. Whilst it is possible to disaggregate the coarse particle concentrations into a component which is diluted by increasing windspeed and a component which increases with windspeed and is hence possibly attributable to wind-induced resuspension processes, the latter is only a minor proportion of the total coarse particle concentration. There are appreciable weekday-to-weekend and day-to-night differences between coarse particle concentrations which are most marked at the urban sites indicative of anthropogenic activities being a source of coarse particles. The clearest indication of the likely predominant source of coarse particles arises from an analysis of a data set derived from an urban street canyon site after subtraction of measurements from a nearby urban background location. The data indicate strong relationships of both fine and coarse incremental particle concentrations in the street canyon with incremental NO_x. If incremental fine particles and coarse particles are attributed to exhaust emissions and vehicle-induced resuspension, respectively, then it may be concluded that vehicle-induced resuspension provides a source strength approximately equal to that of exhaust emissions. An analysis of the coarse particle concentration data suggest that episodes of elevated coarse particle concentrations alone very rarely lead to exceedence of the UK air quality standard for PM₁₀ of 50 μg m⁻³ measured as a 24-h running mean.     

Evaluation of the efficiency of a Venturi scrubber in particulate matter collection smaller than 2.5 µm emitted by biomass burning

Environmental Science and Pollution Research - Energy demand has increased worldwide, and biomass burning is one of the solutions most used by industries, especially in countries that have a great...     

Aluminium foil dampened the adverse effect of 2100 MHz mobile phone–induced radiation on the blood parameters and myocardium in rats

Mobile phones emit a radiofrequency radiation (RFR) that might have adverse health effects. We aimed to investigate the possible protective effects of aluminium foil (AF) as a physical shield against the RFR from mobile phones on the blood parameters and the myocardium in rats. The effects of whole body 2100 MHz with 0.84–1.86 W/kg of SAR, 4 h/day for 30 days Global System for Mobile Communications (GSM)-RFR exposure for 4 h/day for 30 days on blood parameters (i.e. haemoglobin, leucocytes, thrombocytes, erythrocyte sedimentation rate, white blood cell differential count, corticosterone, CKMB), and the histology of myocardium were investigated. Three-month-old male rats (n?=?32) were studied and randomised equally in the following four groups: K1 (non-AF non-RFR control), K2 (AF non-RFR control), P1 (non-AF RFR-exposed), P2 (AF RFR-exposed). Data were analysed with level of significance of p?<?0.05. In P1, lower leucocytes and neutrophils counts with high corticosterone levels were found compared with the control groups, whilst a significantly higher CKMB was observed compared with P2 (p?=?0.034). Lower cardiomyocyte counts congruent to the area fraction of the non-fibrotic myocardium were observed in P1 compared with the other groups (p?<?0.01). AF might decrease the inflammatory-oxidative stress on rodent’s blood cells and myocardium induced by the exposures of radiofrequency radiation of the mobile phones.

     

An observational study of the HONO–NO2 coupling at an urban site in Guangzhou City,South China

The temporal behavior of HONO and NO₂ was investigated at an urban site in Guangzhou city, China, by means of a DOAS system during the Pearl River Delta 2006 intensive campaign from 10 to 24 July 2006. Within the whole measurement period, unexpected high HONO mixing ratios up to 2 ppb were observed even during the day. A nocturnal maximum concentration of about 8.43 ± 0.4 ppb was detected on the night of 24 July 2006. Combining the data simultaneously observed by different instruments, the coupling of HONO–NO₂ and the possible formation sources of HONO are discussed. During the measurement period, concentration ratios of HONO to NO₂ ranged from (0.03 ± 0.1) to (0.37 ± 0.09), which is significantly higher than previously reported values (0.01–0.1). Surprisingly, in most cases a strong daytime correlation between HONO and NO₂ was found, contrary to previous observations in China. Aerosol was found to have a minor impact on HONO formation during the whole measurement period. Using a pseudo steady state approach for interpreting the nocturnal conversion of NO₂ to HONO suggests a non-negligible role of the relative humidity for the heterogeneous HONO formation from NO₂.     

Stabilization of heavy metals in municipal sewage sludge by freeze–thaw treatment with a blend of diatomite,FeSO4, and Ca(OH)2

In this work, the effects of diatomite with 15% FeSO₄?7H₂O and 7.5% Ca(OH)₂ on sludge stabilization were investigated using batch leaching tests. The influence of cell rupture caused by freezing and thawing on stabilization was also evaluated. The results indicated that the optimal diatomite percentage was 2%. Cell rupture by freezing and thawing reduced heavy metal leachability, followed by cell death and decrease of organic groups. The concentration of heavy metals in sludge leachate increased after cell rupture, indicating that the heavy metal leachability was reduced after freezing and thawings. Moreover, the stabilization effects were generally improved after freezing and thawing. As compared with the stabilization of the original sludge, the unstable fractions decreased and the residual fractions of the heavy metals increased in the stabilized sludge after cell rupture.

Implications: This study developed a method to stabilize heavy metals in municipal sewage sludge. Diatomite combined with FeSO₄·7H₂O and Ca(OH)₂ improved the treatment of sewage sludge contaminated by heavy metals. Cell lysis by freeze–thaw treatment reduced the risk of leaching heavy metals caused by cell death and decreased major organic groups in the sludge.