Article

Atmospheric alcohols and aldehydes concentrations measured in Osaka, Japan and in Sao Paulo, Brazil

June 2001
Atmospheric Environment 35(18):3075-3083

June 2001
35(18):3075-3083

DOI:10.1016/S1352-2310(01)00136-4

Authors:

Ha Thi-Hoang Nguyen

ChemTrace

Norimichi Takenaka

Osaka Prefecture University

Show all 7 authorsHide

The use of alcohol fuel has received much attention since 1980s. In Brazil, ethanol-fueled vehicles have been currently used on a large scale. This paper reports the atmospheric methanol, ethanol and isopropanol concentrations which were measured from May to December 1997, in Osaka, Japan, where alcohol fuel was not used, and from 3 to 9 February 1998, in Sao Paulo, Brazil, where ethanol fuel was used. The alcohols were determined by the alkyl nitrite formation reaction using gas chromatography (GC-ECD) analysis. The concentration of atmospheric alcohols, especially ethanol, measured in Sao Paulo were significantly higher than those in Osaka. In Osaka, the average concentrations of atmospheric methanol, ethanol, and isopropanol were 5.8±3.8, 8.2±4.6, and 7.2±5.9ppbv, respectively. The average ambient levels of methanol, ethanol, and isopropanol measured in Sao Paulo were 34.1±9.2, 176.3.±38.1, and 44.2±13.7ppbv, respectively. The ambient levels of aldehydes, which were expected to be high due to the use of alcohol fuel, were also measured at these sampling sites. The atmospheric formaldehyde average concentration measured in Osaka was 1.9±0.9 ppbv, and the average acetaldehyde concentration was 1.5±0.8ppbv. The atmospheric formaldehyde and acetaldehyde average concentrations measured in Sao Paulo were 5.0±2.8 and 5.4±2.8ppbv, respectively. The C2H5OH/CH3OH and CH3CHO/HCHO were compared between the two measurement sites and elsewhere in the world, which have already been reported in the literature. Due to the use of ethanol-fueled vehicles, these ratios, especially C2H5OH/CH3OH, are much higher in Brazil than these measured elsewhere in the world.

Concentrations of Volatile Organic Compounds in the Megacity of São Paulo in 2006 and 2011/2012 – A Comparative Study

Article

Full-text available

Dec 2020

he focus of this study was to measure the Volatile Organic Compounds (VOCs) concentrations in the megacity – São Paulo Metropolitan Area (SPMA). The measurements analyzed in this study included 78 hydrocarbon (HC) samples collected during 2006, and 66 samples of HC, 62 of aldehydes and 42 of ethanol collected during 2011-2012. The observational results showed that the consumption of ethanol, gasoline and diesel from 2006 to 2012 increased by 64 %, 23 % and 25 %, respectively, with substantial changes in the atmospheric composition. The 10 most abundant VOCs in the atmosphere found during 2011/2012 at CETESB IPEN/USP air quality monitoring station were ethanol, acetaldehyde, formaldehyde, acetone, propane, ethene, ethane, butane, 1-ethyl-4-methyl benzene, and 1,2,4-trimethyl benzene. During the 2006 campaign, alkanes represented 54.8 % of the total HC concentration, alkenes 29.2 %, aromatics 13.6 %, and alkadienes 2.4 %. On the other hand, during the 2011-2012 campaign, aldehydes represented 35.3 % of the VOCs, ethanol 22.6 %, aromatics 15.5 %, alkanes 13.5 %, acetone 6.8 %, alkenes 6.0 %, and alkadienes with less than 0.1 %. An increase in VOCs concentrations in the SPMA atmosphere from 2006 to 2012, such as aldehydes and aromatics (which are important ozone precursors) was measured.

36389-110079-1-PB

Article

Full-text available

Dec 2020

The focus of this study was to measure the Volatile Organic Compounds (VOCs) concentrations in the megacity – São Paulo Metropolitan Area (SPMA). The measurements analyzed in this study included 78 hydrocarbon (HC) samples collected during 2006, and 66 samples of HC, 62 of aldehydes and 42 of ethanol collected during 2011-2012. The observational results showed that the consumption of ethanol, gasoline and diesel from 2006 to 2012 increased by 64 %, 23 % and 25 %, respectively, with substantial changes in the atmospheric composition. The 10 most abundant VOCs in the atmosphere found during 2011/2012 at CETESB IPEN/USP air quality monitoring station were ethanol, acetaldehyde, formaldehyde, acetone, propane, ethene, ethane, butane, 1-ethyl-4-methyl benzene, and 1,2,4-trimethyl benzene. During the 2006 campaign, alkanes represented 54.8 % of the total HC concentration, alkenes 29.2 %, aromatics 13.6 %, and alkadienes 2.4 %. On the other hand, during the 2011-2012 campaign, aldehydes represented 35.3 % of the VOCs, ethanol 22.6 %, aromatics 15.5 %, alkanes 13.5 %, acetone 6.8 %, alkenes 6.0 %, and alkadienes with less than 0.1 %. An increase in VOCs concentrations in the SPMA atmosphere from 2006 to 2012, such as aldehydes and aromatics (which are important ozone precursors) was measured.

Disentangling vehicular emission impact on urban air pollution using ethanol as a tracer

Article

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Jul 2018

The Sao Paulo Metropolitan Area is a unique case worldwide due to the extensive use of biofuel, particularly ethanol, by its large fleet of nearly 8 million cars. Based on source apportionment analysis of Organic Aerosols in downtown Sao Paulo, and using ethanol as tracer of passenger vehicles, we have identified primary emissions from light-duty-vehicles (LDV) and heavy-duty-vehicles (HDV), as well as secondary process component. Each of those factors mirror a relevant primary source or secondary process in this densely occupied area. Using those factors as predictors in a multiple linear regression analysis of a wide range of pollutants, we have quantified the role of primary LDV or HDV emissions, as well as atmospheric secondary processes, on air quality degradation. Results show a significant contribution of HDV emissions, despite contributing only about 5% of vehicles number in the region. The latter is responsible, for example, of 40% and 47% of benzene and black carbon atmospheric concentration, respectively. This work describes an innovative use of biofuel as a tracer of passenger vehicle emissions, allowing to better understand the role of vehicular sources on air quality degradation in one of most populated megacities worldwide.

Heterogeneous Interaction of Isopropanol with Natural Gobi Dust

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Sep 2016
ENVIRON SCI TECHNOL

The adsorption of isopropanol on Gobi dust was investigated in the temperature (T) and relative humidity (RH) ranges of 273 – 348 K and <0.01 – 70%, respectively, using zero air as bath gas. The kinetic measurements were performed using a novel experimental setup combining Fourier-Transform InfraRed spectroscopy (FTIR) and Selected-Ion Flow-Tube Mass Spectrometry (SIFT-MS) for gas-phase monitoring. The initial uptake coefficient, γ0, of isopropanol was measured as a function of several parameters (concentration, temperature, relative humidity, dust mass). γ0 was found independent on temperature while it was inversely dependent on relative humidity according to the empirical expression: γ0 = 5.37 × 10-7/(0.77+RH0.6). Furthermore, the adsorption isotherms of isopropanol were determined and the results were simulated with the Langmuir adsorption model to obtain the partitioning constant, KLin, as a function of temperature and relative humidity according to the expressions: KLin = (1.1 ± 0.3) × 10-2 exp [(1764±132)/T] and KLin = 15.75/(3.21+RH1.77). Beside the kinetics, a detailed product study was conducted under UV irradiation conditions (350-420 nm) in a photochemical reactor. Acetone, formaldehyde, acetic acid, acetaldehyde, carbon dioxide and water were identified as gas-phase products. Besides, the surface products were extracted and analysed employing HPLC; Hydroxyacetone, formaldehyde, acetaldehyde, acetone and methylglyoxal were identified as surface products while the formation of several other compounds were observed but were not identified. Moreover, the photo-activation of the surface was verified employing Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTs).

Assessing the Levels and Health Risk of Atmospheric Formaldehyde in Makkah, Saudi Arabia

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Jul 2015

Atmospheric Formaldehyde (HCHO) was monitored in four sites on the Holy Mosque of Makkah, Saudi Arabia during August, 2013. The daily mean concentrations of HCHO were ranged from 1.09-18.92 g/m3. The levels of HCHO were significantly higher than the permissible exposure limit (0.042 μg/m3) of the Occupational Safety and Health Administration (OSHA). However, it were not exceeded the recommended exposure limit of the National Institute for Occupational Safety and Health (20 μg/m3) and Egyptian law 4/1994 (0.37 mg/m3). Spatial variations of HCHO concentrations most probably due to variations in local meteorology and traffic flow, which was considered the main source of emissions. Exposure doses for various age groups were estimated, which ranged from 0.000004 to 0.000259 mg/kg/day. Maximum exposure dose was recorded for boys (age 12-14 years) and children (6-8 years) and minimum for females (19-65 years).

Formation of alkoxymethyl hydroperoxides and alkyl formates from simplest Criegee intermediate (CH2OO) + ROH (R=CH3, CH3CH2, and (CH3)2CH) reaction systems

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Mar 2024
THEOR CHEM ACC

Gas-phase reactions involving simplest Criegee intermediate (CH2OO) have been the current hot topic due to its vital role in atmospheric chemistry. In this study, high-level ab initio calculations are used to investigate the energetics and kinetics for the reaction of CH2OO + ROH → ROCHO + H2O (R=CH3, CH3CH2 and (CH3)2CH). Energies of the stationary points are computed at the CCSD(T)/M06-2X/6-311++G(3d,3pd)//M06-2X/6-311++G(3d,3pd) level of theory. Reaction is going through a 1,2-addition and water elimination step leading to the formation of alkoxymethyl hydroperoxides and alkyl formates, respectively. The barrier heights for the 1,2-addition step with methanol, ethanol, and isopropanol were found to be − 3.1, − 3.7, and − 4.8 kcal mol⁻¹, and water elimination steps were found to be 2.2, 1.5, and 1.6 kcal mol⁻¹, respectively, relative to the energies of the starting reactants. The rate constants for addition and elimination channels were calculated using canonical variational transition state theory in conjugation with small-curvature tunneling and the interpolated single point energy method between the temperature range of 200 and 500 K. In addition, the thermochemistry analysis indicates that addition and elimination channels are thermodynamically feasible and the formation of alkyl formates is entropically more favored when compared to the formation of alkoxymethyl hydroperoxide along the reaction path in the potential energy surface. The pressure-dependent microcanonical rate constants for both addition and elimination channels were also estimated using the Rice–Ramsperger–Kassel–Marcus theory and discussed in this study.

Dynamics of collisions and uptake of alcohol molecules with hydrated nitric acid clusters

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We investigate the collisions of different alcohol molecules with hydrated nitric acid clusters using a molecular beam experiment and molecular dynamics simulations. The uptake cross sections σ p for the molecules...

Bimolecular sinks of Criegee intermediates derived from Hydrofluoroolefins – A Computational Analysis

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Aug 2023

A novel range of stabilised Criegee intermediate (sCI) species with halogenated substituent groups have been identified as products to the reaction between with gaseous ozone and hydrofluoroolefins (HFOs), a series of recently-developed and increasingly prevalent haloalkene refrigerants. The bimolecular chemistry of this group of hydrofluoroolefin-derived sCIs (HFO-sCIs) has yet to be explored in any significant detail so this work evaluates the reaction chemistry of common tropospheric gaseous species with the following group of HFO-sCIs: syn- & anti-CF3CHOO & syn- & anti-CF3CFOO. Using high-level theoretical calculations (DF-HF/DF-LCCSD(T)-F12a//B3LYP/aug-cc-pVTZ), this study demonstrates that HFO-sCIs will deplete many pollutants (e.g. HCHO, SO2 & H2S) but also act as a source of other atmospheric contaminants (e.g. SO3 & TFA). The bimolecular reactivity of the HFO-sCIs were compared against CH2OO, the most frequently studied sCI, for which the general reactivity trend has been identified: kTHEO (syn-CF3CHOO) < kTHEO (anti-CF3CHOO) ≈ kTHEO (CH2OO) ≪ kTHEO (anti-CF3CFOO) < kTHEO (syn-CF3CFOO). In general syn & anti-CF3 substituents reduce overall sCI reactivity compared to similar non-halogenated sCI species, whereas both syn & anti-F substituents significantly increase HFO-sCI reactivity. While HFO-sCI reactivity is largely dictated by the identity and location of the sCI substituent groups, there are co-reactants that alter these observed trends in reactivity, for example HCl reacts more rapidly with CH2OO than it does with syn- & anti-CF3CFOO.

Fuel saving and lower pollutants emissions using an Ethanol-fueled engine in a hydraulic hybrid passengers vehicle

Article

Jul 2021
ENERGY

This paper aims to compare the behavior of ethanol-fueled vehicles when operating exclusively with an internal combustion engine (ICE) and when using a small series hydraulic drivetrain in simulated standardized and real-world driving cycles. The computational models use fuel consumption and emissions maps acquired experimentally in stationary conditions from a multi-cylinder engine in previous work. The hydraulic hybrid powertrain uses the power generated by a pump driven by the ICE or stored in a hydro-pneumatic accumulator to accelerate the vehicle through a hydraulic motor connected to the differential box. Furthermore, a multi-objective optimization tool was used to size the hydraulic components and to calculate the values of the control variables for activating the motor-pump system, in order to achieve the compromise solution of minimum fuel consumption and emissions. The series hydraulic hybrid architecture implemented showed the possibility of reducing fuel consumption mainly in urban routes. The hybrid model optimized for reducing engine-out emissions pointed out the potential of reducing up to 47.2% and 20.7% the CO 2 and NO x emissions levels in the real-world driving cycles, respectively. Furthermore, the optimized solution of lower engine-out emissions also showed potential between 30.17% and 44.14% of fuel-saving in urban routes with frequent stop-and-go events.

One decade of VOCs measurements in São Paulo megacity: Composition, variability, and emission evaluation in a biofuel usage context

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Jun 2020
SCI TOTAL ENVIRON

Production of Acetaldehyde from Ethanol in Coastal Waters

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Apr 2020
ENVIRON SCI POLLUT R

Interest in understanding the cycling of ethanol in the environment has grown as ethanol use as a gasoline additive has increased. The production of acetaldehyde from ethanol was measured in Southern California coastal seawater. The rate of increase of acetaldehyde was positively correlated with the rate constant for ethanol biodegradation and bacteria count and was consistent with two consecutive first-order reactions where acetaldehyde is first biologically produced from ethanol then consumed. Correlation with bacteria counts suggested that acetaldehyde degradation was also a biological process. The rate constants for acetaldehyde production from ethanol and acetaldehyde loss averaged 3.0 ± 3.4 × 10⁻³ min⁻¹ and 2.3 ± 4.5 × 10⁻² min⁻¹ respectively. The branching ratio for acetaldehyde production from ethanol was 0.46 ± 0.26 and estimated acetaldehyde biological production rates ranged from 0.022 to 0.800 nM min⁻¹. With high bacterial counts, biological production rates from ethanol exceeded photochemical production rates from chromophoric dissolved organic matter. Overall, acetaldehyde production rates were larger than biodegradation rates, suggesting these waters are a source of acetaldehyde to the atmosphere. Extrapolation to higher ethanol concentrations associated with spills suggests that the production rate of acetaldehyde will initially increase and then decrease as ethanol concentrations increase.

Biological Degradation of Ethanol in Southern California Coastal Seawater

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Oct 2019
MAR CHEM

The increased use of ethanol as an additive in gasoline is expected to increase atmospheric ethanol levels. Understanding future impacts requires an understanding of the current atmospheric ethanol budget. Air-sea exchange is one of the largest sources of uncertainty in budget estimates. Understanding processes that produce or destroy ethanol in seawater will help constrain air-sea exchange estimates. The rate of biological consumption of ethanol in seawater was measured in Southern California surface coastal water sampled from a tidally flushed river mouth over a six-month period. First-order rate constants (k) for biological degradation of approximately ambient ethanol levels of 89 nM ranged from zero to 1.9 ± 0.1 × 10⁻² min⁻¹ with an average of 3.8 ± 5.9 × 10⁻³ min⁻¹ (n = 20). This corresponds to an average biological turnover time (1/k) of approximately 4.4 h or an average biological half-life (0.693/k) of approximately 3 h. There were several rain events over this time period resulting in flow from upstream in the river; these were associated with increased bacterial levels, higher absorption coefficients and reduced salinity. Rate constants, in general, increased with the number of bacterial colony forming units in the water sample. Excluding the two rate constant maxima events the background biological degradation rate constant in the absence of rain/bacteria input from upstream, is 1.3 ± 1.0 × 10⁻³ min⁻¹. This corresponds to an average biological turnover time of approximately 13 h and an average biological half-life of approximately 9 h. Autoclaved samples (to remove bacteria) showed no measurable ethanol degradation, suggesting that chemical loss processes are not significant.

Chemical characteristics of atmospheric carbonyl compounds and source identification of formaldehyde in Wuhan, Central China

Article

May 2019
ATMOS RES

The chemical characteristics of carbonyl compounds were investigated concurrently at urban (ZY) and suburban (JX) sites in Wuhan in 2017. Thirteen carbonyl compounds were quantified, with average total mixing ratios of 11.29 ± 3.85 ppbv at ZY and 8.72 ± 3.75 ppbv at JX. Formaldehyde (HCHO), acetaldehyde (CH3CHO) and acetone (CH3COCH3) were the three most abundant atmospheric carbonyl compounds, accounting for >85% of the total carbonyl compound mixing ratio at both sites. HCHO exhibited highest concentrations during summer and lowest concentrations during winter at ZY and JX. In contrast, CH3CHO and CH3COCH3 showed an opposite seasonal trend, suggesting that HCHO may be mainly generated by photochemical reactions in summer, while CH3CHO and CH3COCH3 might be originate from primary emissions in winter. Diurnal variations were assessed, with HCHO exhibiting peak values at midnight in all seasons, with levels associated with diesel-fuel vehicle emissions. High ratios of C1/C2 and C2/C3 were observed in summer at ZY and JX, suggesting biogenic sources significantly contribute to carbonyl compound formation. Furthermore, linear regression analysis showed a high HCHO contribution from primary sources in winter (73.5% at ZY, 58.6% at JX) and secondary sources in summer (67.2% at ZY, 47.4% at JX). The results of this study will help formulate effective emission control strategies for carbonyl pollution in Wuhan.

Effect of Seasonal Variation on the Levels and Behaviours of Formaldehyde in the Atmosphere of a Suburban Area in Cairo, Egypt

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Dec 2018

Formaldehyde (HCHO) is a carcinogenic pollutant, has an active role in tropospheric photochemistry, and can be affected by seasonal variations. To our knowledge, this is the first comprehensive study of the effect of seasonal variation on the levels and behaviours of HCHO in the atmosphere of a suburban area (15 May City) in Cairo. Daytime and nighttime measurements of HCHO were performed from March 2014 to February 2015. The highest average daily concentrations of HCHO were found in summer and the lowest in winter. The difference was statistically significant (p≤0.001). Daily average HCHO concentrations in spring, summer, autumn and winter were higher than the corresponding values in many polluted cities in the world. This was true for both weekdays and weekends. HCHO was higher in daytime than nighttime on weekdays and weekends, and the differences in mean concentrations were statistically significant (p ≤0.001), except during the autumn and winter on weekends. Therefore, the contribution of photochemical reactions in the observed levels of HCHO might be greater than that of traffic emissions. This was further proved by the significant positive correlation found between daytime HCHO concentrations and temperature. HCHO concentrations were higher on weekdays than weekends, the differences in mean concentrations were statistically significant (p≤0.001). This may be attributed to higher emission of HCHO from higher traffic intensity during daytime. Significant positive correlations (p≤0.001) were found between daytime and nighttime HCHO concentrations, both on weekdays and weekends suggesting that HCHO comes from the same sources.

An Extended Computational Study of Criegee Intermediate - Alcohol Reactions

Article

Dec 2018

High level ab initio calculations (DF-LCCSD(T)-F12a//B3LYP/aug-cc-pVTZ) are performed on a range of stabilized Criegee intermediate (sCI) – alcohol reactions, computing reaction coordinate energies, leading to the formation of α-alkyoxyl-alkyl-hydroperoxides (AAAHs). These potential energy surfaces are used to model bimolecular reaction kinetics over a range of temperatures. The calculations performed in this work reproduce the complicated temperature dependent reaction rates of CH2OO and (CH3)2COO with methanol, which have previously been experimentally determined. This methodology is then extended to compute reaction rates of 22 different Criegee intermediates with methanol, including several intermediates derived from isoprene ozonolysis. In some cases, sCI-alcohol reaction rates approach those of sCI-(H2O)2. This suggests that in regions with elevated alcohol concentrations, such as urban Brazil, these reactions may generate significant quantities of AAAHs, and may begin to compete with sCI reactions with other trace tropospheric pollutants such as SO2. This work also demonstrates the ability of alcohols to catalyse the 1,4-H transfer unimolecular decomposition of α-methyl substituted sCIs.

Formaldehyde and acetaldehyde in the atmosphere of Salvador-Ba, Brazil, using passive sampling

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Apr 2017

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Nov 2016

This paper reviews the serviceability of hydrous ethanol as a clean, cheap and green renewable substitute fuel for spark ignition engines and discusses the comparative chemical and physical properties of hydrous ethanol and gasoline fuels. The significant differences in the properties of hydrous ethanol and gasoline fuels are sufficient to create a significant change during the combustion phase of engine operation and consequently affect the performance of spark-ignition (SI) engines. The stability of ethanol-gasoline-water blends is also discussed. Furthermore, the effects of hydrous ethanol, and its blends with gasoline fuel on SI engine combustion characteristics, cycle-to-cycle variations, engine performance parameters, and emission characteristics have been highlighted. Higher water solubility in ethanol-gasoline blends may be obviously useful and suitable; nevertheless, the continuous ability of water to remain soluble in the blend is significantly affected by temperature. Nearly all published engine experimental results showed a significant improvement in combustion characteristics and enhanced engine performance for the use of hydrous ethanol as fuel. Moreover, carbon monoxide and oxides of nitrogen emissions were also significantly decreased. It is also worth pointing out that unburned hydrocarbon and carbon dioxide emissions were also reduced for the use of hydrous ethanol. However, unregulated emissions such as acetaldehyde and formaldehyde were significantly increased.

Experimentally Determined Site-Specific Reactivity of the Gas-Phase OH and Cl + i-Butanol Reactions Between 251 and 340 K

Article

Nov 2016

Product branching ratios for the gas-phase reactions of i-butanol, (CH3)2CHCH2OH, with OH radicals (251, 294, and 340 K) and Cl atoms (294 K) were quantified in an environmental chamber study and used to interpret i-butanol site-specific reactivity. i-butyraldehyde, acetone, acetaldehyde, and formaldehyde were observed as major stable end-products in both reaction systems with carbon mass balance indistinguishable from unity. Product branching ratios for OH oxidation were found to be temperature dependent with the α, β, and γ channels changing from 34 ± 6 to 47 ± 1%, 58 ± 6 to 37 ± 9%, and 8 ± 1 to 16 ± 4%, respectively, between 251 and 340 K. Recommended temperature dependent site-specific modified Arrhenius expressions for the OH reaction rate coefficient are (cm3 molecule–1 s–1): kα(T) = 8.64 × 10–18 T1.91 exp(666/T) kβ(T) = 5.15 × 10–19 T2.04 exp(1304/T) kγ(T) = 3.20 × 10–17 T1.78 exp(107/T) kOH(T) = 2.10 × 10–18 T2 exp(–85/T) exp(-61.69/T) where kTotal(T) = kα(T) + kβ(T) + kγ(T) + kOH(T). The expressions were constrained using the product branching ratios measured in this study and previous total phenomenological rate coefficient measurements. The site-specific expressions compare reasonably well with recent theoretical work. It is shown that use of i-butanol would result in acetone as the dominant degradation product under most atmospheric conditions.

Concentrations and physicochemical speciation of heavy metals in urban runoff sediment from São Gonçalo—Rio de Janeiro/Brazil

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Aug 2016
ENVIRON EARTH SCI

Urban runoff sediment samples were analyzed for heavy metal concentrations in different neighborhoods in São Gonçalo, Metropolitan region of Rio de Janeiro-Brazil. This study was undertaken to assess the anthropogenic impact of metal concentrations of urban roadside sediments from São Gonçalo and to estimate the potential mobility of selected metals (Zn, Cu, Pb, Cr and Ni) using a sequential partitioning extraction. The concentrations of heavy metals in this work were compared with reported values from other cities and urban areas. This study highlights the urban runoff sediment as a potential source for heavy metals. The physicochemical speciation of heavy metal highlight the potential bioavailability for all metals, but Cr. Three contamination indexes: geoaccumulation index, contamination factor and Pollution Load Index, were used in order to assess the level of metal contamination in the study area, which demonstrated the contamination originating from the urban runoff sediments.

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Conference Paper

Full-text available

Feb 2015

Ethanol production from cassava using a newly isolated thermotolerant yeast strain

Article

Full-text available

Aug 2014
Sci Asia

Efficient ethanol production using thermotolerant yeast strains was carried out with a newly isolated yeast strain called 267. Strains were isolated with an enriched technique consisting of a blackstrap molasses medium supplemented with 40 ml/l of ethanol at 25-28°C. The results revealed that 33 strains produced ethanol at 45°C in the cassava starch hydrolysate medium, pH 4.5, which was composed of 180 g/l reducing sugar and 0.5 g/l (NH4)2SO4, with a shaking speed of 120 rpm. The highest ethanol concentrations (26.2, 26.2, 23.6, and 22.5 g/l) were found from Pichia kudriavzevii strains PBB511-1, TM512-2, CPY514-1, and TG514-2, respectively. The yeast strain PBB511-1, which produced the highest ethanol yield, was selected for ethanol production in the shaking flask at 45°C. Ethanol production reached the highest level after 36 h in a medium composed of 180 g/l reducing sugar, 0.5 g/l (NH4)2SO4, 0.5 g/l KH2PO4, 0.5 g/l MgSO47H2O, and 1 g/l yeast extract. It produced 37 g/l ethanol, with a productivity of 1.03 (g/l)/h and a yield of 40% of the theoretical yield. The ethanol production by batch fermentation at 45°C was performed in a 7-l jar fermenter with an agitation speed of 300 rpm and an aeration rate of 0.2 vvm throughout the fermentation. The results implied that the maximum ethanol concentration was 42.4 g/l after 48 h, at a rate of 0.88 (g/l)/h and a yield of 46% of the theoretical yield. © 2014, Science Society of Thailand under Royal Patronage. All rights reserved.

Simplified Modeling of Tropospheric Ozone Formation Considering Alternative Fuels Using

Article

Full-text available

Nov 2014

Brazilian cities have been constantly exposed to air quality episodes of high ozone concentrations (O3). Known for not be emitted directly into the environment, O3is a result of several chemical reactions of other pollutants emitted to atmosphere. The growth of vehicle fleet and government incentives for using alternative fuels like ethanol and Compressed Natural Gas (CNG) are changing the Brazilian Metropolitan Areas in terms of acetaldehyde and formaldehyde emissions, Volatile Organic Compounds (VOC's) present in the atmosphere and known to act on the kinetics of ozone. Driven by high concentrations of tropospheric ozone in urban/industry centers and its implications for environment and population health, the target of this work is understand the kinetics of ozone formation through the creation of a mathematical model in FORTRAN 90, describing a system of coupled ordinary differential equations able to represent a simplified mechanism of photochemical reactions in the Brazilian Metropolitan Area. Evaluating the concentration results of each pollutant were possible to observe the precursor’s influence on tropospheric ozone formation, which seasons were more conducive to this one and which are the influences of weather conditions on formation of photochemical smog. © 2014, Universidade Federal do Rio de Janeiro. All rights reserved.

On-road emissions of carbonyls from vehicles powered by biofuel blends in traffic tunnels in the Metropolitan Area of Sao Paulo, Brazil

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May 2015
ATMOS ENVIRON

Substrate-Dependent rRNA Production in an Airborne Bacterium

Article

Aug 2014

Bacteria become aerosolized by a variety of processes and remain in the atmosphere for days. Many studies have characterized bacteria in air, but little is known regarding whether airborne bacteria are active. Here, we show that a bacterial strain previously isolated from air, Sphingomonas aerolata NW12, exhibited metabolic activity while in the airborne state. Airborne cells incubated in rotating gas phase bioreactors in the presence of known growth substrates acetic acid and ethanol in the gaseous phase had higher rRNA to rRNA gene content than airborne cells without growth substrates. This demonstrates that this species of airborne bacteria has a differential metabolic response to gaseous substrates in the aerial environment with an increasing rRNA content, suggesting that the cells have the potential to produce proteins while aloft.

Ethanol, acetaldehyde, and methanol in the gas phase and rainwater in different biomes and urban regions of Brazil

Article

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SCI TOTAL ENVIRON

Vertical profiles of volatile organic compounds and fine particles in atmospheric air by using an aerial drone with miniaturized samplers and portable devices

Article

Full-text available

May 2023
ATMOS CHEM PHYS

The increase in volatile organic compound (VOC) emissions released into the atmosphere is one of the main threats to human health and climate. VOCs can adversely affect human life through their contribution to air pollution directly and indirectly by reacting via several mechanisms in the air to form secondary organic aerosols. In this study, an aerial drone equipped with miniaturized air-sampling systems including up to four solid-phase microextraction (SPME) Arrows and four in-tube extraction (ITEX) samplers for the collection of VOCs, along with portable devices for the real-time measurement of black carbon (BC) and total particle numbers at high altitudes was exploited. In total, 135 air samples were collected under optimal sampling conditions from 4 to 14 October 2021 at the boreal forest SMEAR II station, Finland. A total of 48 different VOCs, including nitrogen-containing compounds, alcohols, aldehydes, ketones, organic acids, and hydrocarbons, were detected at different altitudes from 50 to 400 m above ground level with concentrations of up to 6898 ng m−3 in the gas phase and 8613 ng m−3 in the particle phase. Clear differences in VOC distributions were seen in samples collected from different altitudes, depending on the VOC sources. It was also possible to collect aerosol particles by the filter accessory attached on the ITEX sampling system, and five dicarboxylic acids were quantified with concentrations of 0.43 to 10.9 µg m−3. BC and total particle number measurements provided similar diurnal patterns, indicating their correlation. For spatial distribution, BC concentrations were increased at higher altitudes, being 2278 ng m−3 at 100 m and 3909 ng m−3 at 400 m. The measurements aboard the drone provided insights into horizontal and vertical variability in BC and aerosol number concentrations above the boreal forest.

Quantum chemical modeling of organic enhanced atmospheric nucleation: A critical review

Article

Full-text available

May 2023

Aerosol particles are important for our global climate, but the mechanisms and especially the relative importance of various vapors for new particles formation (NPF) remain uncertain. Quantum chemical (QC) studies on organic enhanced nucleation has for the past couple of decades attracted immense attention, but very little remains known about the exact organic compounds that potentially are important for NPF. Here we comprehensively review the QC literature on atmospheric cluster formation involving organic compounds. We outline the potential cluster systems that should be further investigated. Cluster formation involving complex multi‐functional organic accretion products warrant further investigations, but such systems are out of reach with currently applied methodologies. We suggest a “cluster of functional groups” approach to address this issue, which will allow for the identification of the potential structure of organic compounds that are involved in atmospheric NPF. This article is categorized under: Theoretical and Physical Chemistry > Reaction Dynamics and Kinetics Software > Quantum Chemistry Theoretical and Physical Chemistry > Thermochemistry Molecular and Statistical Mechanics > Molecular Interactions

Molecular Mechanisms and Atmospheric Implications of Criegee Intermediate-Alcohol Chemistry in the Gas Phase and Aqueous Surface Environments

Article

Sep 2020
J PHYS CHEM A

Criegee intermediates and alcohols are important species in atmosphere. In this study, we use quantum chemistry and Born-Oppenheimer molecular dynamics (BOMD) simulations to investigate the reaction between methanol/ethanol and Criegee intermediates (anti- or syn-CH3CHOO) in the gas phase and at the air-water interface. Reactions at the interface are found to be much faster than those in the gas phase. When water molecules are available, loop structures can be formed to facilitate the reaction. In addition, non-loop reaction pathways characterized by the formation of hydrated proton, although with a low possibility, are also identified at the air-water interface. Implications of our results on the fate of Criegee intermediates in atmosphere are discussed, which deepen our understanding of Criegee intermediate-alcohol chemistry in humid environments.

Atmospheric fate of a series of saturated alcohols: kinetic and mechanistic study

Article

Full-text available

Jan 2020
ACP

The atmospheric fate of a series of saturated alcohols (SAs) was evaluated through kinetic and reaction product studies with the main atmospheric oxidants. These SAs are alcohols that could be used as fuel additives. Rate coefficients (in cm3 molecule−1 s−1) measured at ∼298 K and atmospheric pressure (720±20 Torr) were as follows: k1 ((E)-4-methylcyclohexanol + Cl) = (3.70±0.16) ×10-10, k2 ((E)-4-methylcyclohexanol + OH) = (1.87±0.14) ×10-11, k3 ((E)-4-methylcyclohexanol + NO3) = (2.69±0.37) ×10-15, k4 (3,3-dimethyl-1-butanol + Cl) = (2.69±0.16) ×10-10, k5 (3,3-dimethyl-1-butanol + OH) = (5.33±0.16) ×10-12, k6 (3,3-dimethyl-2-butanol + Cl) = (1.21±0.07) ×10-10, and k7 (3,3-dimethyl-2-butanol + OH) = (10.50±0.25) ×10-12. The main products detected in the reaction of SAs with Cl atoms (in the absence/presence of NOx), OH radicals, and NO3 radicals were (E)-4-methylcyclohexanone for the reactions of (E)-4-methylcyclohexanol, 3,3-dimethylbutanal for the reactions of 3,3-dimethyl-1-butanol, and 3,3-dimethyl-2-butanone for the reactions of 3,3-dimethyl-2-butanol. Other products such as formaldehyde, 2,2-dimethylpropanal, and acetone have also been identified in the reactions of Cl atoms and OH radicals with 3,3-dimethyl-1-butanol and 3,3-dimethyl-2-butanol. In addition, the molar yields of the reaction products were estimated. The products detected indicate a hydrogen atom abstraction mechanism at different sites on the carbon chain of alcohol in the case of Cl reactions and a predominant site in the case of OH and NO3 reactions, confirming the predictions of structure–activity relationship (SAR) methods. Tropospheric lifetimes (τ) of these SAs have been calculated using the experimental rate coefficients. Lifetimes are in the range of 0.6–2 d for OH reactions, 7–13 d for NO3 radical reactions, and 1–3 months for Cl atoms. In coastal areas, the lifetime due to the reaction with Cl decreases to hours. The calculated global tropospheric lifetimes, and the polyfunctional compounds detected as reaction products in this work, imply that SAs could contribute to the formation of ozone and nitrated compounds at local, regional, and even global scales. Therefore, the use of saturated alcohols as additives in diesel blends should be considered with caution.

Improving continuous chemiluminescence determination method of formaldehyde in the atmosphere: reducing interference of acetaldehyde and others by using iodoform reaction

Article

Jun 2019

The continuous and selective determination method of formaldehyde (HCHO) in ambient air using chemiluminescence method has been developed. The counter current flow tube was used to collect gaseous formaldehyde. The major interferences of HCHO determination from acetaldehyde, ethanol, and ferrous ion were removed by applying iodoform reaction. Effect of acetaldehyde on chemiluminescence signal of formaldehyde at the same concentration was reduced from 19 to 0.3% by applying iodoform reaction. Subsequently, HCHO was online detected by measuring chemiluminescence produced from the reaction of HCHO, gallic acid, H2O2, and KOH. The limit of detection (S/N = 3) was 4.5 ppbv in air. The calibration graph was linear up to 6.25 ppmv. HCHO concentration measured by the present method showed good agreement with that obtained by the 2–4 DNPH-HPLC method.

Effects of High Acidity on Phase Transitions of Organic Aerosol

Article

Mar 2018

Aerosol particle morphology influences the effect of particles on climate. Recent studies have documented the high acidity found in many ambient aerosol particles. The effect of this acidity on phase transitions of mixed organic/inorganic aerosol particles has not been addressed. To investigate this effect, six organic compounds and ammonium sulfate are investigated individually with varying amounts of sulfuric acid to determine the role of low pH on the separation, efflorescence, and deliquescence transitions. All phase transitions were affected by the addition of sulfuric acid. This effect was attributed primarily to the change in the identity of the inorganic component as the ammonium:sulfate ratio (ASR) was changed from two to one and a half to one. The separation relative humidity (SRH) decreased with increasing amounts of sulfuric acid for each system studied, with the largest effect seen in compounds that have a lower SRH when mixed with ammonium sulfate. Control studies without an inorganic salt revealed that for some systems, phase separation occurs for mixtures of sulfuric acid and an organic acid. Overall, it was found that for aerosol particles at low pH (≤ 0.35) composed of organic acids and inorganic salts, phase separation can be impeded in some cases.

Kinetics of the Reactions between the Criegee Intermediate CH 2 OO and Alcohols

Article

Dec 2017

Reactions of the simplest Criegee intermediate (CH2OO) with a series of alcohols have been studied in a flash photolysis flow reactor. Laser photolysis of diiodomethane at 355 nm in the presence of molecular oxygen was used to produce CH2OO, and the absolute number densities were determined as a function of delay time from analysis of broadband transient absorption spectra obtained using a pulsed LED. The kinetics for the reactions of CH2OO with methanol, ethanol, and 2-propanol were measured under pseudo-first-order conditions at 295 K, yielding rate constants of (1.4 ± 0.4) × 10–13 cm³ s–1, (2.3 ± 0.6) × 10–13 cm³ s–1, and (1.9 ± 0.5) × 10–13 cm³ s–1, respectively. Complementary ab initio calculations were performed at the CCSD(T)/aug-cc-pVTZ//CCSD/cc-pVDZ level of theory to characterize stationary points on the reaction enthalpy and free energy surfaces and to elucidate the thermochemistry and mechanisms. The reactions proceed over free energy barriers of ∼8 kcal mol–1 to form geminal alkoxymethyl hydroperoxides: methoxymethyl hydroperoxide (MMHP), ethoxymethyl hydroperoxide (EMHP), and isopropoxymethyl hydroperoxide (PMHP). The experimental and theoretical results are compared to reactions of CH2OO with other hydroxylic compounds, such as water and carboxylic acids, and trends in reactivity are discussed.

Variability in the primary emissions and secondary gas and particle formation from vehicles using bio-ethanol mixtures

Article

Full-text available

Oct 2017

Implication: The use of bio-ethanol can significantly reduce petroleum use and greenhouse gas emissions worldwide. Given the extent of its use, it is important to understand its effect on urban pollution. There is a controversy on whether there is a reduction or increase in PM emission when using ethanol blends. Primary emissions of THC, CO, CO2, NOx and NMHC for both cars decreased as the fraction of ethanol in gasoline increased. Using a photochemical chamber we have found a decrease in the formation of secondary particles and the time required to form secondary PM is longer, when using higher ethanol blends.

A Simple Method for Simultaneous Determination of Acetaldehyde, Acetone, Methanol, and Ethanol in the Atmosphere and Natural Waters

Article

May 2017

Although there has been a dramatic increase in the use of ethanol fuel in several countries, there is a great lack of data related to the abundance of this alcohol and associated species in the atmosphere and in natural waters. This data paucity is mainly due to the fact that their low concentrations in the environment pose a considerable analytical challenge. This work presents a simple and low-cost method to simultaneously determine acetaldehyde, acetone, methanol, and ethanol at environmentally relevant concentrations in the atmosphere and in a variety of natural waters. The target compounds present in the aqueous phase were analyzed by conventional headspace gas chromatography with flame ionization detection. External pretreatment of the aqueous samples was not necessary, providing savings in the cost and time of analysis. Satisfactory recoveries (96–108%) and good agreement with a high performance liquid chromatography method for determination of acetaldehyde, methanol, and ethanol endorsed the accuracy of the proposed method. Precision was better than 15% for the lowest concentration quality control sample tested, and was better than 8% for higher concentrations. Linearity (r) was better than 0.99 and the limits of detection for acetaldehyde, acetone, methanol, and ethanol were 0.20, 0.21, 1.45, and 0.41 μmol L−1, respectively. The sensitivity of the method enabled the measurement of the target compounds in atmospheric samples collected in Brazil ranging from 3.6 to 20.6 ppbv. Rainwater, freshwater, and coastal seawater sample concentrations ranged from <0.20 to 0.85 μmol L−1 for acetaldehyde, from 0.21 to 0.98 μmol L−1 for acetone, from 6.20 to 15.7 μmol L−1 for methanol, and from 0.41 to 7.61 μmol L−1 for ethanol.

An estimate of the global budget and distribution of ethanol using a global 3-D atmospheric chemistry transport model STOCHEM-CRI

Article

Feb 2017

The atmospheric global budget and distribution of ethanol have been investigated using a global 3-dimensional chemistry transport model, STOCHEM-CRI. Ethanol, a precursor to acetaldehyde and peroxyacetyl nitrate (PAN), is found throughout the troposphere with a global burden of 0.024–0.25 Tg. The atmospheric lifetime of ethanol is found to be 1.1–2.8 days, which is in excellent agreement with estimates established by previous studies. The main global source of ethanol is from direct emission (99%) and the remainder (1%) being produced via peroxy radical reactions. In terms of removal rates of ethanol in the atmosphere, oxidation by hydroxyl radicals (OH) accounted for 51%, dry deposition 8% and wet deposition accounted for 41%. Globally there are significant concentrations of ethanol over equatorial Africa, North America and parts of Asia with considerably higher concentrations modelled over Saudi Arabia and Eastern Canada. Through comparison of measured and modelled ethanol data, it is apparent that the underestimation of the source strength of ethanol and the coarse resolution of the STOCHEM-CRI model produce the discrepancies between the model and the measured data mostly in urban areas. The increased vegetation and anthropogenic emissions of ethanol lead to an increase in the production of acetaldehyde (by up to 90%) and peroxyacetyl nitrate (by up to 10%) which disrupts the NOx-ozone balance, promoting ozone production (by up to 1.4%) in the equatorial regions.

The global atmospheric budget of ethanol revisited

Article

Full-text available

Jan 2012

Ethanol is an important biogenic volatile organic compound, which is increasingly used as a fuel for motor vehicles; therefore, an improved understanding of its atmospheric cycle is important. In this paper we use three sets of observational data, measured emissions of ethanol from living plants, measured concentrations of ethanol in the atmosphere and measured hydroxyl concentrations in the atmosphere (by methyl chloroform titration), to make two independent estimates related to the rate of cycling of ethanol through the atmosphere. In the first estimate, simple calculations give the emission rate of ethanol from living plants as 26 (range, 10–38) Tg yr−1. This contributes significantly to the total global ethanol source of 42 (range, 25–56) Tg yr−1. In the second estimate, the total losses of ethanol from the global atmosphere are 70 (range, 50–90) Tg yr−1, with about three-quarters of the ethanol removed by reaction with hydroxyl radicals in the gaseous and aqueous phases of the atmosphere, and the remainder lost through wet and dry deposition to land. These values of both the source of ethanol from living plants and the removal of atmospheric ethanol via oxidation by hydroxyl radicals (derived entirely from observations) are significantly larger than those in recent literature. We suggest that a revision of the estimate of global ethanol emissions from plants to the atmosphere to a value comparable with this analysis is warranted.

Characterization of the variation of carbonyl compounds concentrations before, during, and after the renovation of an apartment at Niterói, Brazil

Article

Full-text available

Aug 2016
ENVIRON SCI POLLUT R

This study demonstrated, for the first time, Fe(III)/peroximonosulphate (PMS) could be an efficient advanced oxidation process (AOP) for wastewater treatment. Bisphenol A (BPA) was chosen as a model pollutant in the present study. Fe(III)-activated PMS system proved very effective to eliminate 92.18% of BPA (20 mg/L) for 30-min reaction time at 0.50 mM PMS, 1.5 g/L Fe(III), pH 7.0. The maximum degradation of BPA occurred at neutral pH, while it was suppressed at both strongly acidic and alkaline conditions. Organic and inorganic ions can interfere with system efficiency either positively or negatively, so their interaction was thoroughly investigated. Furthermore, the presence of organic acids also affected BPA degradation rate, especially the addition of 10 mM citric acid decreased the degradation rate from 92.18 to 66.08%. Radical scavenging experiments showed that SO4•– was the dominant reactive species in Fe(III)/PMS system. A total of 5 BPA intermediates were found by using LC/MS. A possible degradation pathway was proposed which underwent through bridge cleavage and hydroxylation processes. Acute toxicity of the BPA degradation products was assessed using Escherichia coli growth inhibition test. These findings proved to be promising and economical to deal with wastewater using iron mineral for the elimination of organic pollutants. Graphical abstract

Gas phase kinetics of the reaction system of 2NO(2)<-> N2O4 and simple alcohols between 293-358 K

Article

Full-text available

Aug 2005
POL J CHEM

The reversible reactions between nitrogen dioxide and alcohols (CH3OH, CH3CH2OH, CH3CH2CH2OH, CH3CHOHCH3) have been studied in the gas phase, using the spectrophotometric method. RONO (R=CH3, CH3CH2, CH3CH2CH2, CH3CHCH3) were identified by UV spectra. The equilibrium constants as well as the bimolecular rate constants were determined by computer modeling, using the programme MINICHEM. We calculated the following values for the forward rate constants k(3)(av): (3.0 +/- 0.9) x 10(-18), (8.0 +/- 2.4) x 10(-18), (5.4 +/- 1.6) x 10(-18), (2.0 +/- 0.6) x 10(-18) cm(3) molec(-1) s(-1) and the equilibrium constants K-av: 100 +/- 30, 40 +/- 12, 109 +/- 33, 39 +/- 12 at 298 K for the reactions with methanol, ethanol, 1-propanol and 2-propanol, respectively. The temperature dependence of the rate constants and the equilibrium constants were studied and it allowed to obtain the activation energy for the forward and for the reverse reaction, as well as thermochemical parameters. The equilibrium constants and the rate constants suggest that symmetrical N2O4 is the reactive species.

FDATMOS16 Atmospheric ethanol in London and the potential impacts of future fuel formulations

Article

Dec 2015

There is growing global consumption of non-fossil fuels such as ethanol made from renewable biomass. Previous studies have shown that one of the main air quality disadvantages of using ethanol blended fuels is a significant increase in the production of acetaldehyde, an unregulated and toxic pollutant. Most studies on the impacts of ethanol blended gasoline have been carried out in the US and Brazil, with much less focus on the UK and Europe. We report time resolved measurements of ethanol in London during the winter and summer of 2012. In both seasons the mean mixing ratio of ethanol was around 5 ppb, with maximum values over 30 ppb, making ethanol currently the most abundant VOC in London air. We identify a road transport related source, with ‘rush-hour’ peaks observed. Ethanol is strongly correlated with other road transportrelated emissions, such as small aromatics and light alkanes, and has no relationship to summer biogenic emissions. To determine the impact of road transport-related ethanol emission on secondary species (i.e. acetaldehyde and ozone), we use both a chemically detailed box model (incorporating the Master Chemical Mechanism, MCM) and a global and nested regional scale chemical transport model (GEOS-Chem), on various processing time scales. Using the MCM model, only 16% of the measured acetaldehyde was formed from ethanol oxidation. However, the model significantly underpredicts the total levels of acetaldehyde, indicating a missing primary emission source, that appears to be traffic-related. Further support for a primary emission source comes from the regional scale model simulations, where the observed concentrations of ethanol and acetaldehyde can only be reconciled with the inclusion of large primary emissions. Although only constrained by one set of observations, the regional modelling suggests a European ethanol source similar in magnitude to that of ethane (60 Gg yr–1) and greater than that of acetaldehyde (10 Gg yr–1). The increased concentrations of ethanol and acetaldehyde from primary emissions impacts both radical and NOx cycling over Europe, resulting in significant regional impacts on NOy speciation and O3 concentrations, with potential changes to human exposure to air pollutants.

Seasonal, diurnal and nocturnal variations of carbonyl compounds in the semi-urban environment of Orléans, France

Article

Jan 2016
J ENVIRON SCI-CHINA

Atmospheric carbonyls were measured at a semi-urban site in Orléans, France, from October 2010 to July 2011. Formaldehyde, acetaldehyde and acetone were found to be the most abundant carbonyls, with average concentrations of 3.1, 1.0, 2.0 ppb, respectively in summer, 2.3, 0.7, 2.2 ppb, respectively in autumn, 2.2, 1.0, 2.1 ppb, respectively in spring, and 1.5, 0.7, 1.1 ppb, respectively in winter. Photo-oxidation of volatile organic compounds (VOCs) was found to make a remarkable contribution to atmospheric carbonyls in the semi-urban site based on the distinct seasonal and diurnal variations of the carbonyls, as well as the significantly positive correlations between the carbonyls and ozone. The significantly negative correlations between NOx and O3 as well as the carbonyls and the positive correlations between wind speed and O3 as well as the carbonyls implied that the carbonyls and O3 at the semi-urban site were probably formed during air mass transport from neighboring cities.

Development of Methods for Measuring the Intramolecular Carbon Isotopic Composition of Organic Molecules

Article

Mar 2014
BUNSEKI KAGAKU

A stable isotopic composition in materials has provided useful information concerning their origins and histories. For a carbon isotopic measurement of a single organic molecule, the total organic carbon contained in the molecule should be converted quantitatively to carbon dioxide. Therefore, the carbon isotopic composition represents an average value for the molecules. In principle, information concerning the origins and histories of organic molecules exists at the specific position of the molecule. To retrieve diverse, complex, and specific information of their origins and histories from organic molecules, a measurement of the position-specific carbon isotopic composition is required. So far, a difficult measurement have prevented any development for the position-specific isotopic measurement. Here, we describe recent advances in analytical instrumentation concerning a position-specific carbon isotopic measurement for organic molecules using gas chromatography-combustion-isotope ratio mass spectrometry combined with an on-line pyrolysis technique.

Políticas energéticas y salud urbana Colombia

Research

Full-text available

Oct 2015

Hector Garcia-Lozada

Se estudió la incidencia de la debilidad del régimen político colombiano en la estructuración de las políticas energéticas (1990-2006) y en la forma como se incorpora, o se ignora, la dimensión salud en estas políticas. Desde el enfoque cualitativo interpretativo y el análisis crítico de contenidos de las leyes, decretos y reglamentos, que conforman la expresión jurídica de las políticas se estructuró un modelo integrador para revelar el modo, los momentos y las condiciones de inclusión (o marginalización) de la dimensión salud en las políticas energéticas.

Impregnation versus Bulk Synthesis: How the Synthetic Route Affects the Photocatalytic Efficiency of Nb/Ta:N Codoped TiO2 Nanomaterials

Article

Oct 2015

Selecting the proper doping strategy is essential to control the photocatalytic activity of TiO2-based nanomaterials. In this work, we compare impregnation and bulk synthesis methods for feeding titania nanocrystals with either Nb or Ta as transition metal dopant, and N as nonmetal codopant. The resulting photocatalytic efficiency was tested towards ethanol degradation under either UV or simulated solar irradiation. Microstructure, morphology and electronic properties at various length scales were investigated through XRPD, BET, XPS, DRS and EPR characterizations and complemented by bulk DFT simulations. Under UV irradiation, impregnated samples performed better than bulk synthesis ones, with Ta-doped powders being more efficient than Nb-doped ones. Under simulated solar irradiation just the opposite was true, as bulk synthesis Nb-doped materials were the most active ones, while all the impregnated samples were even less performing than the undoped TiO2 reference. On the basis of XPS, EPR, DRS and XRPD results, such differences were attributed to the fact that the bulk synthesis approach produces a more homogeneous distribution of guest dopants within the grains, in conjunction with a higher amount of intrinsic defects (such as O vacancies). Implications of these findings on the engineering of efficient titania photocatalysts are discussed.

Adsorption of 2-propanol on ice probed by ambient pressure X-ray photoelectron spectroscopy

Article

Full-text available

Aug 2015
PHYS CHEM CHEM PHYS

The interaction of 2-propanol with ice was examined via ambient pressure X-ray photoelectron spectroscopy (APXPS), a surface sensitive technique that probes the adsorbed 2-propanol directly with submonolayer resolution. Isothermal uptake experiments were performed on vapor deposited ice at 227 K in the presence of the equilibrium water vapor pressure of 0.05 Torr and 2-propanol partial pressures ranging from 5 × 10(-5) to 2 × 10(-3) Torr. The C 1s APXPS spectra of adsorbed 2-propanol showed two characteristic peaks associated with the COH alcohol group and CMe methyl groups in a 1 : 2 ratio, respectively. Coverage increased with 2-propanol partial pressure and followed first order Langmuir kinetics with a Langmuir constant of K = 6.3 × 10(3) Torr(-1). The 1 : 2 ratio of COH : CMe remained constant with increasing coverage, indicating there is no chemical reaction upon adsorption. The observed Langmuir kinetics using APXPS is consistent with previous observations of other small chain alcohols via indirect adsorption methods using, e.g., Knudsen cell and coated wall flow tube reactors.

Primary emissions and secondary organic aerosol formation from the exhaust of a flex-fuel (ethanol) vehicle

Article

Full-text available

Jul 2015
ATMOS ENVIRON

Incentives to use biofuels may result in increasing vehicular emissions of compounds detrimental to air quality. Therefore, regulated and unregulated emissions from a Euro 5a flex-fuel vehicle, tested using E85 and E75 blends (gasoline containing 85% and 75% of ethanol (vol/vol), respectively), were investigated at 22 and -7C over the New European Driving Cycle, at the Vehicle Emission Laboratory at the European Commission Joint Research Centre Ispra, Italy. Vehicle exhaust was comprehensively analyzed at the tailpipe and in a dilution tunnel. A fraction of the exhaust was injected into a mobile smog chamber to study the photochemical aging of the mixture. We found that emissions from a flex-fuel vehicle, fueled by E85 and E75, led to secondary organic aerosol (SOA) formation, despite the low aromatic content of these fuel blends. Emissions of regulated and unregulated compounds, as well as emissions of black carbon (BC) and primary organic aerosol (POA) and SOA formation were higher at -7C. The flex-fuel unregulated emissions, mainly composed of ethanol and acetaldehyde, resulted in very high ozone formation potential and SOA, especially at low temperature (860 mg O3 km-1 and up to 38 mg C kg-1). After an OH exposure of 10x10E6 cm-3 h, SOA mass was, on average, 3 times larger than total primary particle mass emissions (BC + POA) with a high O:C ratio (up to 0.7 and 0.5 at 22 and -7C, respectively) typical of highly oxidized mixtures. Furthermore, high resolution organic mass spectra showed high 44/43 ratios (ratio of the ions m/z 44 and m/z 43) characteristic of low-volatility oxygenated organic aerosol. We also hypothesize that SOA formation from vehicular emissions could be due to oxidation products of ethanol and acetaldehyde, both short-chain oxygenated VOCs, e.g. methylglyoxal and acetic acid, and not only from aromatic compounds.

Formaldehyde and acetaldehyde measurements in urban atmosphere impacted by the use of ethanol biofuel: Metropolitan Area of Sao Paulo (MASP), 2012–2013

Article

Full-text available

Oct 2014
FUEL

There is a consensus that particulate matter and gases pollutants originating from industry and vehicle emission processes in urban areas are important from the point of view of public health and climate change. Local anthropogenic emissions, especially those resulting from energy generation processes from the industrial and transport sector, are connected with those occurring at the regional and global scales. A major concern in the Metropolitan Area of Sao Paulo (MASP) is the impact of the large scale use of ethanol as a fuel and as an additive for Otto vehicles. In this study, atmospheric concentrations of ozone, nitrogen oxides (NO and NO2), formaldehyde and acetaldehyde were measured in the MASP in Brazil, over four seasons in 2012 and 2013. The results were compared with data collected in previous studies. Our results demonstrate that, although there was a large increase in the number of vehicles in the MASP that use ethanol ("flex-fuel" vehicles), technological advances in vehicle emissions control have prevented any significant increase in the atmospheric concentrations of aldehydes. In addition, an increase in the formaldehyde/acetaldehyde ratio has been observed.

Potential of volatile organic compounds as markers of entrapped humans for use in urban search-and-rescue operations

Article

Full-text available

Feb 2015
TRAC-TREND ANAL CHEM

Volatile organic compounds emitted by a human body form a chemical signature capable of providing invaluable information on the physiological status of an individual and, thereby, could serve as signs-of-life for detecting victims after natural or man-made disasters. In this review a database of potential biomarkers of human presence was created on the basis of existing literature reports on volatiles in human breath, skin emanation, blood, and urine. Approximate fluxes of these species from the human body were estimated and used to predict their concentrations in the vicinity of victims. The proposed markers were classified into groups of different potential for victim detection. The major classification discriminants were the capability of detection by portable, real-time analytical instruments and background levels in urban environment. The data summarized in this review are intended to assist studies on the detection of humans via chemical analysis and accelerate investigations in this area of knowledge.

Evaluation of the concentrations and distribution of carbonyl compounds in selected areas of a Brazilian bus terminal

Article

Jan 2015

This study describes the determination of 30 carbonyl compounds (CCs) in three areas (bus boarding platform, passenger circulation area, and a pastry shop) of the Presidente João Goulart Bus Terminal, located at Niterói City, RJ, Brazil, and in an open area 700 m distant from the terminal. Samples were collected using SEP-PAK cartridges impregnated with 2,4-dinitrophenylhydrazine, during May to July 2012. The hydrazones formed were analyzed using rapid resolution liquid chromatography with UV detection. The studied locations showed distinct profiles of distribution of CC. The circulation area, which is influenced by different pollution sources, presented an intermediate profile between that of the pastry shop and boarding platform. Formaldehyde and acetaldehyde were the most abundant CC, but acetaldehyde predominated in the pastry shop once it is a by-product of baking yeast fermentation. Samples taken in the pastry shop and circulation area showed significant concentrations of hexanaldehyde and nonanaldehyde emitted during cooking. The pastry shop showed the largest level of total CC among the studied areas followed by the circulation area, the boarding platform, and the open area.

Megaciudades y contaminación atmosférica

Article

O Cerca de la mitad de la población mundial vive hoy en áreas urbanas debido a la oportunidad de una mejor calidad de vida. Muchos de estos centros urbanos están expandiéndose rápidamente, llevándonos al crecimiento de megaciudades, que se definen como áreas metropolitanas con poblaciones que exceden los diez millones de habitantes. Esta concentración de personas y actividades están ejerciendo cada vez más estrés en el medio ambiente, con impactos en los niveles urbano, regional y global. En décadas recientes, la contaminación del aire se ha convertido en uno de los problemas más importantes de las megaciudades. Inicialmente, los principales contaminantes del aire eran compuestos de azufre, que se generaban principalmente por la combustión del carbón. Hoy, smog fotoquímico—inducido principalmente por el tráfico, pero también por la actividad industrial, la generación de electricidad, y solventes—se han convertido en la principal preocupación para la calidad del aire, mientras que el azufre es uno de los principales problemas de muchas ciudades en el mundo en desarrollo. La contaminación atmosférica tiene serio impacto en la salud pública, causa bruma urbana y regional, y tiene el potencial para contribuir significativamente al cambio climático. Aún así, con la adecuada planeación, las megaciudades pueden abordar eficientemente los problemas de calidad del aire, a través de medidas como la aplicación de nuevas tecnologías de control de emisiones y el desarrollo de sistemas de transporte masivo. Este estudio se enfoca en nueve centros urbanos, seleccionados como casos de estudio para cotejar su calidad del aire desde distintas perspectivas: desde ciudades en las naciones industrializadas hasta ciudades del mundo en desarrollo. Mientras que cada ciudad—sus problemas, recursos y expectativas—es única, la necesidad de un enfoque holístico para estos complejos problemas ambientales es la misma. No hay una estrategia única para reducir la contaminación en las megaciudades; varias medidas serán necesarias para mejorar la calidad del aire. La experiencia nos muestra que una fuerte voluntad política además de diálogo público es esencial para implementar efectivamente las regulaciones requeridas para atacar los problemas de calidad del aire.

Spatial and Temporal Variations of Atmospheric Concentrations of Carbonyl Compounds in Seoul Metropolitan Area

Article

Full-text available

Apr 2008

The purpose of this study is to evaluate concentrations of carbonyl compounds during summer season in Seoul metropolitan area. The air samples were collected at 7 sites in this area from June 2001 to June 2003. The carbonyl compounds were analyzed by DNPH/HPLC method. The analytical method applied in this study showed good repeatability, linearity, and sensitivity. The most abundant carbonyl was formaldehyde (average 4.48 ppb), and followed by acetone, acetaldehyde, methyl ethyl ketone, butyraldehyde, propionaldehyde and benzaldehyde, respectively. Concentrations of carbonyl compounds in June were higher than those in August. There was not only higher solar radiation but also higher ozone concentration in June than in August. As a result o photochemical reactions, carbonyl compounds from both primary and secondary sources are likely to contribute to the formation of ozone. The contributions to photochemical ozone creation of two carbonyl compounds such as formaldehyde and acetaldehyde were estimated to be about 70%. Ratios of formaldehyde to acetaldehyde in this study ranged from 1.13 to 4.26, which are generally equivalent levels to those of other urban areas in domestic and foreign countries.

Comparison between two carbonyl measurement methods in the atmosphere

Article

Full-text available

Jan 1999
Analusis

Two atmospheric aldehyde sampling techniques, the impinger method in which aldehydes are trapped in a 2,4-dinitrophenylhydrazine acidified acetonitrile solution, and the method in which aldehydes are captured in 2,4-dinitrophenylhydrazine acidified coated cartridges commercialised by the WATERS(R), were compared for blank values, sample preservation, ozone action, and water influence. The two methods were tested in a Paris atmosphere and the influence of a KI ozone scrubber has been evaluated. Except for acetaldehyde and benzaldehyde, the two techniques do not give coherent results. When no ozone scrubber is used, the cartridge technique gives systematically lower values. Bad correlation has been obtained between data with scrubber and data without scrubber for the impinger technique except for acetaldehyde. For the cartridge technique, the correlation is better for all the aldehydes but higher values are found when a scrubber is used, except for formaldehyde. Ozone action leads to 2,4-dinitrophenylhydrazone destruction, but also to formaldehyde 2,4-dinitrophenylhydrazone formation by reaction between airborne volatile organic compounds and ozone on the cartridge surfaces.

Potential Air Quality Effects of Using Ethanol−Gasoline Fuel Blends: A Field Study in Albuquerque, New Mexico

Article

Nov 1997

The use of alternate fuels has been proposed as a method of improving urban air quality by reducing combustion-related pollution. One such program mandates the use of oxygenates in the wintertime to reduce CO emissions in cities such as Albuquerque, NM. A field study was conducted in Albuquerque to determine the atmospheric impacts of the use of ethanol fuels. Atmospheric concentrations of ozone, oxides of nitrogen, CO, peroxyacetyl nitrate (PAN), aldehydes, and organic acids were measured in the summer of 1993, before the use of ethanol fuels, and in the winters of 1994 and 1995, during the use of 10% ethanol fuel (>99%). Data showed increased levels of peroxyacetyl nitrate (PAN) and aldehydes in winter. The formaldehyde/acetaldehyde ratio was 1.4, indicating an anthropogenic source, and PAN and acetaldehyde levels were anti-correlated over short time periods, indicating primary acetaldehyde emissions. A comparison of data taken at rural sites south of the city indicates that although there is a significant anthropogenic component to the aldehyde concentrations during the winter, there are also contributions from the photochemical oxidation of natural hydrocarbons.

Reactive Hydrocarbons in the Atmosphere

Article

Jan 1999

Roger Atkinson

The emissions of reactive volatile organic compounds into the atmosphere from biogenic and anthropogenic sources and the subsequent interaction of these organic compounds with oxides of nitrogen in the presence of sunlight lead to the formation of photochemical air pollution, now recognized to affect much of Europe, the United States, and many regions and urban areas elsewhere around the world. The past decade has seen the realization that emissions of organic compounds from biogenic sources (principally from vegetation) may be comparable to, or even dominate over, emissions of organic compounds from anthropogenic sources. Biogenic organics therefore play an important role in the chemistry of the troposphere and influence control strategies aimed at reducing the exposure of human populations to ozone and other manifestations of photochemical air pollution. Organic compounds also are involved in the formation of secondary organic aerosol, the formation of acids in the atmosphere, the potential for global warming, and, for chlorine- and bromine-containing compounds, stratospheric ozone depletion.

Hydrocarbon measurements in the southeastern United States: The Rural Oxidants in the Southern Environment (ROSE) Program 1990

Article

Dec 1995

An automated gas chromatographic system was employed at a rural site in western central Alabama to measure atmospheric hydrocarbons and oxygenated hydrocarbons. Correlation of acetone with methanol suggest that it also, has a significant biogenic source. In spite of the site's rural location, anthropogenic hydrocarbons constituted, on a carbon atom basis, about 21% of the hydrocabron burden measured during the daytime and about 55% at night. Significant diurnal variations of the anthropogenic hydrocarbons, with increases at night, appeared to be driven by the frequent formation of a shallow nocturnal boundary layer. -from Authors

Evaluation of the Performance of DNPH-Coated Silica Gel and C 18 Cartridges in the Measurement of Formaldehyde in the Presence and Absence of Ozone

Article

Jan 1998

Formaldehyde (HCHO) is an important photochemical product generated during the oxidation of volatile organic compounds in the troposphere. Accurate HCHO concentrations are essential for developing a quantitative basis for ozone formation and represent a primary monitoring objective for the Photochemical Assessment and Monitoring Stations (PAMS). In the PAMS network, measurements of HCHO are conducted by a derivatization method using cartridges coated with 2,4-dinitrophenylhydrazine (DNPH). In this study, a manifold system has been designed to evaluate the performance, accuracy, and importance of interfer ences of DNPH-coated silica gel and C18 cartridges using gas-phase calibration standards. Compared to the independent gas-phase calibration values, HCHO values from silica gel cartridges were typically 5% lower than the reference values over the range of 2−25 ppbv; C18 cartridge values were systematically lower by 20%. These results were found to be independent of the level of humidity in the system. The HCHO measurements of the two cartridge systems were highly correlated and yielded the regression equation, [HCHO]C18 = 0.84[HCHO]Sil Gel. Measurement of HCHO in the presence of ozone by silica gel cartridges led to a negative interference, which has been widely reported. The magnitude of the interference was greater than 50% under conditions representative of urban environments (HCHO = 5 ppb; O3 = 120 ppb). The interference was routinely removed through the use of a potassium iodide (KI) scrubber or denuder. However, these devices were found to require modest water concentrations (>4000 ppmv; RH > 10% at 25 °C) to remove ozone effectively. With the C18 cartridges, the presence of ozone in the airstream produced a positive interference for the HCHO−hydrazone using standard analysis techniques. These results suggest that under ambient conditions offsetting errors are possible with the use of C18 cartridges, if ozone removal devices are not used. However, with proper precautions, either of these cartridges can be a highly effective means of measuring formaldehyde and other carbonyl compounds in urban atmospheres.

Aldehydes, carboxylic acids and inorganic nitrate during NSMCS

Article

Dec 1988
Atmos Environ

Daniel Grosjean

This article describes the methods and results of a study involving measurements of ambient levels of carboxylic acids (formic, acetic and oxalic), aldehydes (formaldehyde, acetaldehyde, propanal, n-butanal, n-pentanal and benzaldehyde) and total inorganic nitrate (nitric acid + particulate nitrate) during the Nitrogen Species Methods Comparison Study (NSMCS). Results for inorganic nitrate obtained using Teflon-nylon filter packs are compared to those obtained with nylon-nylon filter units and to those obtained by other methods during NSMCS. Calculations are presented of the distribution of gas phase nitrogen among NO, NO2, HONO2 and PAN, and of the positive bias due to PAN and HONO2 in NOx measurements by chemiluminescence. Data for aldehydes and carboxylic acids are discussed in terms of sampling efficiency, gas-aerosol phase distribution, possible interferents (e.g. PAN as acetate on alkaline filters), diurnal variations, and relative importance of emissions vs in-situ daytime and night-time formation and removal processes.

Urban air pollution in Brazil: Acetaldehyde and other carbonyls

Article

Dec 1990

We have measured ambient levels of carbonyls in three major urban areas of Brazil: Sao Paulo, Rio de Janeiro and Salvador. The most abundant carbonyls were acetaldehyde (up to 63 μg m−3, or 35 ppb) followed by formaldehyde (up to 42 μg m−3, or 34 ppb), and acetone (up to 20 ppb). Levels of 10 other aliphatic and aromatic carbonyls were in the range 0–5 ppb. Total carbonyl concentrations were in the range 11–75 ppb. Indoor levels were also measured at several locations in Salvador. High levels of acetaldehyde, 430 μg m−3 or 240 ppb, were measured in a highway tunnel.Using carbonyl/CO concentration ratios, mobile source emissions of carbonyls are estimated for the Sao Paulo area. Ambient levels of acetaldehyde and acetaldehyde/formaldehyde concentration ratios in Brazil are compared to those for other urban areas, and are briefly discussed in relation with the large scale use of ethanol as a vehicle fuel.

On-road carbon monoxide emission measurement comparisons for the 1988-1989 Colorado oxy-fuels program

Article

Jun 1990

The University of Denver's remote sensor for carbon monoxide has been used to perform a study of CO emissions from in-use vehicles during the State of Colorado's 1988-1989 Oxygenated Fuels program. More than 117,000 vehicle exhaust measurements were performed on warm vehicles at two locations in the Denver area, with more than 4,900 vehicles identified by make and model year through license plate registration information. The results for the oxygenated fuels period show a statistically significant decrease in average CO emissions of 16 {plus minus} 3% at both locations. This decrease is shown to be independent of initial emissions for the dirtiest 25% of the fleet and not significant for the cleanest 75%. The decrease is shown not to be attributable to location, vehicle load, speed, fleet mix, fleet age, or age distribution changes. Less than 10% of the vehicles account for half of the CO emissions. Very few of these (0.3%) are less than 2 model years old, but a sizable fraction (26%) are 1983 model year and newer.

Modeling the Effect of Ethanol/Gasoline Blend Usage on Ozone Formation in Urban Areas

Article

Jul 1986
J Air Pollut Contr Assoc

The potential effects of ozone formation which would result if the 1985 vehicle fleet were converted from gasoline to ethanol/gasoiine blends were investigated using the EKMA approach. Changes In vehicular emissions were used to calculate changes in ambient HC reactivities and ambient levels of HC, NOx and CO for a number of scenarios. Ozone formation was then modeled for each scenario. Effects on ozone formation were not significant unless the usage of ethanol/gasoline blends resulted in deterioration of the emissions control systems. Ambient NOx/HC ratios were shown to have a significant effect on ozone formation.

Emissions of volatile organic compounds (primarily oxygenated species) from pasture

Article

May 1998

The volatile organic compound (VOC) emissions from pasture at a site in southeastern Victoria, Australia, were monitored over a 2 year period using a static chamber technique. Fluxes up to 23,000 mug(C)m-2h-1 were detected, with the higher fluxes originating from clover rather than from grass species. Gas chromatographic analyses indicated that emissions from both grass and clover were high in oxygenated hydrocarbons including methanol, ethanol, propanone, butanone, and ethanal, and extremely low in isoprene and monoterpenes. In the case of clover, butanone made up 45-50% of the total emissions. When grass and clover were freshly mown, there were significantly enhanced emissions of VOCs. These enhanced emissions included both those oxygenates emitted from uncut pasture and also C6-oxygenates, including (Z)-3-hexenal, (E)-2-hexenal, (Z)-2-hexen-1-ol, (Z)-3-hexen-1-ol, and (Z)-3-hexenyl acetate. Emissions from the undisturbed pasture increased markedly with temperature and the intensity of solar radiation, peaking at midday and ceasing at night. The fluxes, when normalized to a temperature of 30°C and a light intensity of 1000 muEm-2s-1 were, for grass and clover respectively, about one eighth and two fifths of the equivalent fluxes reported to occur from U.S. woodlands. The annual integrated emission from the pasture was approximately 1.9 g(C)m-2 or 1.3 mg(C)g-1 (dry matter). The large transient fluxes that occurred following physical damaging of the pasture, when integrated over time, could be of the same order as those emissions that were observed from undisturbed pasture. In the case of methanol, and perhaps ethanol, the emissions from grasslands may be significant global sources of these gases.

A new method for determining the concentration of atmospheric alcohols using the nitrite formation reaction

Article

Dec 1999
ANAL CHIM ACTA

A new method for measuring the concentration of atmospheric alcohols was developed and applied to ambient air samples. In the method, air samples were collected in 200ml Pyrex glass bottles whose surface had been cleaned and treated with a chromic acid mixture. Alcohols in the sample were allowed to react in the dark with intentionally added nitrogen dioxide (200ppm by volume (ppmv) concentration level) on the glass surface to yield corresponding alkyl nitrites. The concentration of the nitrite thus yielded is determined separately by gas chromatography (GC) with an electron capture detector (ECD). Alcohol concentration in the sample is calculated using a calibrated conversion factor of each alcohol to its nitrite. Detection limits for methanol, ethanol, and isopropanol are 0.9, 0.7, and 1.8ppbv (parts per billion by volume), respectively, using 500μl injection of the reaction mixture by this method.In order to examine the feasibility of this method for an ambient air sample, several measurements were done. Air samples were taken on a road with heavy traffic near the campus of Osaka Prefecture University. Concentration levels of methanol, ethanol, and isopropanol were 4–10, 3–25, and 1.5–20ppbv, respectively. Diurnal variation of these alcohols’ concentration was also measured. Generally, alcohol concentrations were higher in the evening than those in the daytime, increasing up to the levels of 10–20, 10–25, and 10–20ppbv for methanol, ethanol, and isopropanol, respectively.

Emission Impacts of Electric Vehicles

Article

Sep 1990
J AIR WASTE MANAGE

Alternative vehicular fuels are proposed as a strategy to reduce urban air pollution. In this paper, we analyze the emission Impacts of electric vehicles In California for two target years, 1995 and 2010. We consider a range of assumptions regarding electricity consumption of electric vehicles, emission control technologies for power plants, and the mix of primary energy sources for electricity generation. We find that, relative to continued use of gasoline-powered vehicles, the use of electric vehicles would dramatically and unequivocally reduce carbon monoxide and hydrocarbons. Under most conditions, nitrogen oxide emissions would decrease moderately. Sulfur oxide and particulate emissions would Increase or slightly decrease. Because other areas of the United States tend to use more coal in electricity generation and have less stringent emission controls on power plants, electric vehicles may have less emission reduction benefits outside California.

Potential Air Quality Effects of Using Ethanol−Gasoline Fuel Blends: A Field Study in Albuquerque, New Mexico

Article

Dec 1998

The use of alternate fuels has been proposed as a method of improving urban air quality by reducing combustion-related pollution. One such program mandates the use of oxygenates in the wintertime to reduce CO emissions in cities such as Albuquerque, NM. A field study was conducted in Albuquerque to determine the atmospheric impacts of the use of ethanol fuels. Atmospheric concentrations of ozone, oxides of nitrogen, CO, peroxyacetyl nitrate (PAN), aldehydes, and organic acids were measured in the summer of 1993, before the use of ethanol fuels, and in the winters of 1994 and 1995, during the use of 10% ethanol fuel (>99%). Data showed increased levels of peroxyacetyl nitrate (PAN) and aldehydes in winter. The formaldehyde/ acetaldehyde ratio was 1.4, indicating an anthropogenic source, and PAN and acetaldehyde levels were anti-correlated over short time periods, indicating primary acetaldehyde emissions. A comparison of data taken at rural sites south of the city indicates that although there is a significant anthropogenic component to the aldehyde concentrations during the winter, there are also contributions from the photochemical oxidation of natural hydrocarbons.

Alternative transportation fuels and air quality

Article

Jul 1991

Investigates whether alternative fuels can reduce US reliance on foreign energy sources and minimise combustion-related pollution. Three alternative fuel programs have been mandated in the 1990 Clean Air Act Amendments which have nationwide implications to; control ozone levels; reduce CO emissions; and set a required percentage of low-emission vehicles that must be produced in each new motor vehicle fleet. Alternative, or clean fuels include reformulated gasoline, methanol, compressed natural gas (CNG), and liquid petroleum gas among others. The paper assesses the air quality impact of these fuels with respect to urban ozone, CO, air toxics, and CO2 and compares these figures with emission values for gasoline. In conclusion the author suggests that when urban issues alone are considered, widespread use of CNG-fueled vehicles appears to have the most significant impact among the carbon-containing fuels. -M.Z.Barber

Measurements of hydrocarbons, oxygenated hydrocarbons, carbon monoxide, and nitrogen oxides in an urban basin in Colorado: Implications for emission inventories

Article

Nov 1995

_PRELIMINARY _FINAL Concentrations of a wide variety of volatile organic compounds (VOC) in the C 3 to C 10 range, CO, NO y (total reactive oxidized nitrogen), SO 2 , and meteorological parameters were measured concurrently at a site on the western perimeter of Boulder, Colorado, during February 1991. The measurement site, located some 150 m above the Boulder urban basin, receives air masses typifying averaged local sources. The highest hydrocarbon concentrations observed showed little effects of photochemical loss processes and reflect the pattern of the local emission sources. The observed ratios of CO and the VOCs to NO y are compared to those predicted by the 1985 National Acid Precipitation Assessment Program (NAPAP) inventory. These comparisons indicate (1) good agreement for CO/NO y , (2) significant overpredictions by the NAPAP inventory for many of the hydrocarbon to NO y ratios, (3) much more benzene from mobile sources (and less from area sources) than predicted by the NAPAP inventory, and (4) large underpredictions of the light alcohols and carbonyls by the NAPAP inventory. These first two results are in marked contrast to the conclusions of the recent tunnel study reported by Ingalls in 1989. Source profile reconciliation implies substantial input from both a local propane source and gasoline headspace venting.

Ambient Concentrations of Ethanol and Methyl tert-Butyl Ether in Porto Alegre, Brazil, March 1996−April 1997

Article

Feb 1998

While air quality and other perceived benefits of oxygenated fuel programs are currently the topic of much debate, there are very few reports of ambient concentrations of oxygenated fuels (e.g., ethanol) and fuel additives (e.g., ethanol, methyl tert-butyl ether, hereafter called MTBE) in urban air. Ambient concentrations of MTBE and ethanol have been measured by GC−FID and GC−MS analysis of samples collected in electropolished canisters at a downtown location in Porto Alegre, Brazil, where 17% of the vehicles run on ethanol, 74% run on a mixture of 85% gasoline and 15% MTBE, and 9% use diesel fuel. During the ca. 1-year period of March 20, 1996−April 16, 1997, ambient levels of MTBE ranged from 0.2 to 17.1 ppbv (average = 6.6 ± 4.3 ppbv); those of ethanol ranged from 0.4 to 68.2 ppbv (average = 12.1 ± 13.3 ppbv). Ambient levels of ethanol and MTBE are compared to those of carbon monoxide (for which vehicle exhaust accounts for ca. 99% of total emissions in the city of Porto Alegre) and of acetylene. Linear regression of the ambient concentration data (44 samples) yielded near-zero intercepts and slopes of 11.40 ± 0.45 for acetylene (ppbv) vs CO (ppmv), 1.73 ± 0.20 for MTBE (ppbv) vs CO (ppmv), 0.153 ± 0.016 for MTBE (ppbv) vs acetylene (ppbv), and 4.64 ± 0.78 for ethanol (ppbv) vs CO (ppmv). These slopes together with an estimated vehicle exhaust emission rate for CO in mid-1996 are used to estimate vehicle emission rates of 2338 ± 393 t/year for ethanol and 1668 ± 193 t/year for MTBE.

Measurement of sub-parts-per-billion levels of carbonyl compounds in marine air by a simple cartridge trapping procedure followed by liquid chromatography

Article

Oct 1990

Carbonyl compounds in clean marine air were trapped onto 2,4-dinitrophenylhydrazine- (DNPH-) coated cartridges, and their hydrazone derivatives were separated by HPLC and detected by UV absorbance. More than 20 carbonyl compounds were isolated from marine air with >92% collection efficiency. The technique employs a highly effective reagent purification procedure, which results in much lower blanks compared to previously reported trapping techniques for carbonyl compounds. Blanks were routinely <0.07 ppb for formaldehyde and acetone and <0.02 ppb for the others. Humidity and reactive gases have no detectable effect on collection efficiencies. Carbonyl-DNPH derivatives eluted from the cartridges are stable in acetonitrile for at least 2 weeks, which facilitates field studies. Several previously undetected unknown carbonyl compounds were found in marine air by this technique. Typical results for open ocean and coastal marine air are shown.

2,4-Dinitrophenylhydrazine-coated silica gel cartridge method for determination of formaldehyde in air: identification of an ozone interference

Article

Nov 1989

Two versions of the 2,4-dinitrophenylhydrazine method, a coated silica gel cartridge (solid) and acetonitrile impinger (solvent based), were used simultaneously to sample varied concentrations of ozone (0-770 ppb) and formaldehyde (20-140 ppb). Ozone was found to be a negative interference in the determination of formaldehyde by the 2,4-dinitrophenylhydrazine-coated silica gel cartridge method. At 120 ppb of ozone, formaldehyde at 40 ppb was under-reported by the cartridge method by 34% and at 300 ppb of ozone, formaldehyde measurements were 61% low. Greater losses were seen at higher ozone concentrations. Impinger sampling (2,4-DNPH in acetonitrile) showed no formaldehyde losses due to ozone.

The development of an automated continuous measurement system for the monitoring of HCHO and CH3CHO in the atmosphere by using an annular diffusion scrubber coupled to HPLC

Article

Apr 1999

An automated continuous measurement system for the monitoring of formaldehyde (HCHO) and acetaldehyde (CH3CHO) in the urban atmosphere was developed by using an annular diffusion scrubber in conjunction with a high-performance liquid chromatograph (HPLC). With this technique, atmospheric HCHO and CH3CHO were effectively collected by the annular diffusion scrubber which consists of a porous polytetrafluoroethylene (PTFE) tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine (DNPH) was selected as the scrubbing solution for collecting HCHO and CH3CHO, which are derivatized to 2,4-dinitrophenylhydrazone-formaldehyde (DNPH-HCHO) and 2,4-dinitrophenylhydrazone-acetaldehyde (DNPH-CH3CHO), respectively. An aliquot of the sample solution was automatically injected into an HPLC equipped with a semi-micro ODS column and a UV-VIS detector for separating and determining DNPH-HCHO and DNPH-CH3CHO. All the operations are sequenced by a programmable controller, and automated continuous measurements are performed with a typical temporal resolution of 1 h. The collection efficiencies of HCHO and CH3CHO were about 97% and 93%, respectively, at an air flow rate of 0.2 L/min. The lower detection limits (3σ of the blank hydrazones) of HCHO and CH3CHO were 0.05 ppbv and 0.10 ppbv, respectively, in the case of 12-L air sample volume. Analytical response of a standard solution of DNPH-HCHO and DNPH-CH3CHO by the HPLC during a 10-day continuous measurement was unchanged and the relative standard deviation (RSD) was < 1.0%. Interferences from O3 and NO2 were insignificant in this annular diffusion scrubber method. Both for HCHO and CH3CHO measurements, concentrations from this developed system well agreed with those measured by a DNPH Silica cartridge method.

Method for measurement of volatile oxygenated hydrocarbons in ambient air

Article

Oct 1997
ATMOS ENVIRON

An automated gas chromatographic method for the quantitative determination of oxygenated (C2C5 carbonyls and C1C2 alcohols) and some non-oxygenated (C5C8) hydrocarbons in ambient air has been developed. The analytical system consists of a gas chromatograph with a cryogenic sampling trap, a precolumn for the separation of water and other interfering compounds, a cryogenic focusing trap and two analytical columns connected in series. Substances are detected either by flame ionization or by a mass spectrometer. Ozone is removed by a potassium iodide scrubber placed upstream the sampling trap. External gas standards generated by a permeation device are used for calibration. The detection limits range between 0.03 and 0.08 ng (depending on the compound), equivalent to 5 to 56 ppt in 1 of sampled air. The method was tested by an intercomparison with a different gas chromatographic technique for the determination of NMHC. The system has been applied since 1994 for measurements in ambient air. Data obtained during an intensive campaign in summer 1995 at the field station Wank (1778 m a.s.l.) near Garmisch-Partenkirchen, Germany, are reported and compared with NMHC mixing ratios measured simultaneously in the same air masses.

Sources and sinks of formaldehyde and acetaldehyde: An analysis of Denver's ambient concentration data

Article

Jun 1996
ATMOS ENVIRON

Four-hour average concentration data for formaldehyde and acetaldehyde have been collected in downtown Denver for each winter since December 1987, and on a year-round basis since October 1991. Carbon monoxide measurements have also been made at the same site since October 1991. These data have been analyzed in an attempt to identify the important sources and sinks for these carbonyl compounds in downtown Denver. We have found that motor vehicle emissions are a major source of these compounds all year. Although we do not find evidence for significant net photochemical production, we do find evidence for photochemical sources and sinks of both compounds. We have applied statistical techniques to ambient concentration data that can extract useful information about these atmospheric sources, sinks and processes, in spite of the large day-to-day variability in the data. Formaldehyde concentrations were found to have increased significantly during three recent winters when at least 2.6% oxygen-content fuel was required compared to two earlier winters when at least 2.0% oxygen-content fuel was required. The increase in formaldehyde concentration coincides with the increase in oxygenate content required in the fuel, but may be due to other causes.

Measurements of Lower Carbonyls in Rome Ambient Air

Article

Nov 1996
ATMOS ENVIRON

Ambient levels and diurnal profiles of lower carbonyls were measured in Rome during selected days of summer 1994 and winter 1995. The most abundant carbonyls were formaldehyde (up to 27 ppb) followed by ethanal (< 17 ppb) and acetone (< 9 ppb). Gas-phase concentrations of other seven carbonyls were in the 0–3 ppb range. The results were discussed with respect to direct emissions and photochemical production. Using carbonyl/CO concentration ratios mobil source emissions of carbonyls were estimated for the urban area. The secondary production of C1–C3 aldehydes from reactions of alkenes with O3 and OH radicals during the early morning hours of summer days was also calculated. The daytime pattern of carbonyls was found to be similar to that of toluene in wintertime and close to that of ozone in summer periods conductive to photochemical pollution episodes.

Detection of substantial emissions of methanol from plants to the atmosphere

Article

Aug 1993
Atmos Environ Gen Top

Measurements made on a number of plant species revealed that leaves emit methanol at rates comparable to those of other major biogenic volatile organic compounds, such as isoprene. Methanol emission originated within the leaf, was affected by leaf temperature, and closely followed changes in stomatal conductance. Observed methanol emission rates appear sufficient to be the source of greater-than-expected methanol concentrations recently measured in the rural troposphere. Plant methanol emission to the troposphere may be substantial and may contribute to tropospheric photochemistry and formaldehyde production.

Determination of methanol and ethanol by gas chromatography following air sampling onto florosil cartridges and their concentrations at urban sites in the three largest cities in Brazil

Article

Jun 1999
TALANTA

A new sampling protocol was developed to determine methanol and ethanol in the gas phase, at low concentration levels, in urban atmospheres. The procedure involves collection of air samples (20.0–30.0 l) with three florisil cartridges connected in series, at a flow rate ranging from 1.0 to 2.0 l min−1 and subsequent elution of the alcohols with water. Separation and quantification were done by gas chromatography (GC) coupled with a flame ionization detector, ‘SPI’ injector and column DB WAX (30 m×0.53 mm×1 μm). The minimum mass detected by the method, based on two times the average background mass on the blank cartridges, was 0.3 μg for both alcohols which, for a sampled volume of 30 l, resulted in detection limits of 7.6 and 5.3 ppbV for methanol and ethanol, respectively. The determined alcohol concentrations, in 42 different samples from the three largest cities in Brazil—São Paulo, Rio de Janeiro and Salvador—ranged from 72 ppbV to below the detection limit for methanol and from 355 to 12 ppbV for ethanol.

Improved aqueous scrubber for collection of soluble atmospheric trace gases

Article

Jun 1985

A new concentration technique for the extraction and enrichment of water-soluble atmospheric trace gases has been developed. The gas scrubbing technique efficiently extracts soluble gases from a large volume flow rate of air sample into a small volume of refluxed trapping solution. The gas scrubber utilizes a small nebulizing nozzle that mixes the incoming air with an aqueous extracting solution to form an air/droplet mist. The mist provides excellent interfacial surface areas for mass transfer. The resulting mist sprays upward through the reaction chamber until it impinges upon a hydrophobic membrane that virtually blocks the passage of droplets but offers little resistance to the existing gas flow. Droplets containing the scrubbed gases coalesce on the membrane and drip back into the reservoir for further refluxing. After a suitable concentration period, the extracting solution containing the analyte can be withdrawn for analysis. The nebulization-reflex concentration technique is more efficient (maximum flow of gas through the minimum volume of extractant) than conventional bubbler/impinger gas extraction techniques and is offered as an alternative method.

Formaldehyde and Other Carbonyls in Los Angeles Ambient Air

Article

May 1982

Daniel Grosjean

From selective sampling and liquid chromatography analysis, ambient levels of carbonyl compounds as 2,4-dinitrophenylhydrazones have been measured in the Los Angeles area during severe photochemical pollution episodes. Gas-phase concentrations and diurnal profiles are presented for six carbonyls: formaldehyde (up to 48 ppb), acetaldehyde (less than or equal to 35 ppb), propanal (less than or equal to 14 ppb), butanal (less than or equal to 7 ppb), 2-butanone (less than or equal to 14 ppb), and benzaldehyde (less than or equal to 1 ppb). Also presented are particulate-phase concentrations and particle/gas distribution ratios for five carbonyls. Ambient carbonyl levels are discussed with respect to anthropogenic emissions and to photochemical production and removal in polluted air. Advantages and current limitations of the method employed are briefly discussed.

Atmospheric chemistry of aldehydes: Enhanced peroxyacetyl nitrate formation from ethanol-fueled vehicular emissions

Article

Sep 1988

A preliminary study of the effects of enhanced acetaldehyde emissions from vehicles using ethanol and ethanol-containing fuel on peroxyacetyl nitrate (PAN) concentrations in urban air has been conducted in Rio de Janeiro. During this study, part of the second Rio de Janeiro Aerosol Characterization Study (RIO-JACS II), high concentrations of aldehydes (with low HCHO/CH/sub 3/CHO ratios) were related to enhanced PAN formation rates, especially in the a.m. hours, leading to PAN concentrations as high as 5 ppbv even in the presence of high NO concentrations. Model simulations of smog photochemistry with high aldehyde emissions were in substantial agreement with observations, except nitric acid levels were higher than observed due in part to HNO/sub 3/ loss mechanisms not included in the model (e.g., uptake onto aerosol particles).

Determination of Aliphatic and Aromatic Aldehydes in Polluted Airs as their 2,4-Dinitrophenylhydrazones by High Performance Liquid Chromatography

Article

May 1979

A reversed-phase high performance liquid chromatography system with a LiChrosorb RP-18 column and acetonitrile-water mobile phase has been applied to the determination of C1-C6 aliphatic and aromatic aldehydes in polluted airs such as urban air, industrial emission, auto exhaust, and tobacco smoke. The aldehydes in a sample were allowed to react with 2,4-dinitrophenylhydrazine to form 2,4-dinitrophenylhydrazone derivatives. The derivatives were extracted with chloroform and concentrated. The residue in acetonitrile was analyzed by high performance liquid chromatography. The derivatives of C1-C6 aliphatic aldehydes could be separated from the derivatives of the same molecular weight ketones, and aromatic aldehydes such as benzaldehyde, and isomers of tolualdehydes could be separated without effects of aliphatic carbonyl compounds. The aldehydes in the low ppm or ppb levels in air samples could be determined with good accuracy.

Emission impacts of electric vehicles. Air Waste Management Association 40

Jan 1990
1275

Q Wang
M A Deluchi
D J Sperling

Wang, Q., Deluchi, M.A., Sperling, D.J., 1990. Emission impacts of electric vehicles. Air Waste Management Association 40, 1275.

Comparison between two carbonyl measurement methods in the atmosphere

Jan 1999
45-53

C P Ferrari
R Durand-Joli
P Calier
V Jacob
A Roche
P Foster
P Fresnet

Ferrari, C.P., Durand-Joli, R., Calier, P., Jacob, V., Roche, A., Foster, P., Fresnet, P., 1999. Comparison between two carbonyl measurement methods in the atmosphere. Analysis 27, 45-53.

Urban air pollution in Brazil

Jan 1990
101

Grosjean

Sources and sinks of formaldehyde and acetaldehyde

Jan 1996
2113

Anderson

Hydrocarbon measurements in the southeastern United States

Jan 1995
25945

Goldan

Atmospheric chemistry of aldehydes

Jan 1988
1026

Tanner

Atmospheric alcohols and aldehydes concentrations measured in Osaka, Japan and in Sao Paulo, Brazil

Abstract

No full-text available

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