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PubMed2006

Influence of the addition of sulphate and ferric ions in a methanogenic anaerobic packed-bed reactor treating gasoline-contaminated water.

Benzene, toluene and xylene (BTX) are relatively soluble aromatic compounds of gasoline. Gasoline storage tank leakages generally lead to an extensive contamination of groundwater. In the natural environment for instance, these compounds might be biodegraded under a variety of reducing potentials. The objective of this work was to examine the influence of the addition of sulphate and Fe(OH)3 in a methanogenic horizontal-flow anaerobic immobilized-biomass reactor treating gasoline-contaminated water. Three different conditions were evaluated: methanogenic, sulphidogenic and sulphidogenic with the addition of ferric ions. Methanogenic condition showed the higher BTX degradation rates and the addition of sulphate negatively affected BTX removal rates with the production of H2S. However, the addition of ferric ions resulted in the precipitation of sulphur, improving BTX degradation by the consortium. Metanosphaera sp., Methanosarcina barkeri and Methanosaeta concilii were identified in the consortium by means of 16S and directly related to the addition of ferric ions.

Anaerobiosis↗
PubMedDate not supplied

Challenges in biodegradation of trace organic contaminants--gasoline oxygenates and sex hormones.

Advances in analytical methods have led to the identification of several classes of organic chemicals that are associated with adverse environmental effects. Two such classes of organic chemicals, gasoline oxygenates and sex hormones, are used to illustrate challenges associated with the biodegradation of trace organic contaminants. Gasoline oxygenates can be present in groundwater, alone, or commingled with xylene, at appreciable concentrations. However, target-treated water standards dictate that gasoline oxygenates be reduced to the microgram-per-liter concentration range before consumption. Sex hormones, on the other hand, are present in wastewater matrixes in the part-per-trillion concentration range, and the biggest challenge that must be met, before optimizing their removal, is facilitating their detection.

Biodegradation, Environmental↗
PubMed2004

Rapid drop in infant blood lead levels during the transition to unleaded gasoline use in Santiago, Chile.

This study was conducted to relate blood lead levels in infants to changes in lead emissions in Santiago, Chile, a heavily polluted setting where leaded gasoline began to be replaced with unleaded gasoline in 1993. Over an 18-mo period, 422 infants had blood lead levels, cotinine, and iron status determined at 12 mo. Blood lead levels fell at an average rate of 0.5 microg/dl every 2 mo, from 8.3 to 5.9 microg/dl, as the city experienced a net fall of 30% in the quantity of leaded gasoline sold. Time progression, car ownership, serum cotinine, and type of housing were significantly associated with a blood lead level > or = 10 microg/dl. In this study, the authors demonstrated that infant blood lead levels, even if relatively low, can drop very rapidly in conjunction with decreases in environmental lead exposure.

Carcinogens↗
PubMed2002

The trends of changes in children's blood lead levels since the introduction of lead free gasoline in Shanghai.

OBJECTIVE: To describe trends of changes in blood lead levels in children aged 1 - 6 years during the time period before and after introducing lead free gasoline in Shanghai 1997 and 1999. METHODS: Blood lead levels of 1 969 children aged 1 - 6 years were determined by a sampling survey in five districts of Shanghai in August and September, 1997. Blood lead levels of the same population were re-determined by the same method from April to June in 1998 and from August to September in 1999. Filter paper blood lead test was carried out monthly using the filter paper blood lead proficiency testing program of Centers for Disease Control in the United States. The results from blood lead samples were under acceptable ranges during the study. RESULTS: The geometric means of blood lead levels were 83 microgram/L in 1997, 80 microgram/L in 1998 and 76 microgram/L in 1999, respectively. The prevalence rates of childhood lead poisoning (blood lead level was equal or more than 100 microgram/L) were 37.8% in 1997, 25.7% in 1998 and 24.8% in 1999. The amounts of decrease on average blood lead levels in the five districts between 1997 and 1999 were 10 microgram/L, 11 microgram/L, 6 microgram/L, 4 microgram/L and 2 microgram/L, respectively. CONCLUSION: Lead poisoning is a preventable disease. The average levels of lead in young children in Shanghai decreased significantly after the introduction of lead free gasoline to Shanghai. Lead emissions from vehicles running on leaded gasoline was one of the important contributors to increase the children's blood lead levels in Shanghai. Lead poisoning is not evenly distributed among children in Shanghai, resulting in the different levels of decline.

Child, Preschool↗
PubMed2003

Evaluation of biomass production in unleaded gasoline and BTEX-fed batch reactors.

BTEX removal under aerobic conditions by unleaded gasoline acclimated biomass and BTEX acclimated biomass, and the effect of surfactant on BTEX biodegradation were evaluated. The effect of BTEX concentration as the sole source of carbon for biomass acclimation and the effect of yeast extract on cell growth in unleaded gasoline-fed reactors were also evaluated. For the unleaded gasoline acclimated biomass, benzene was shown the most recalcitrant among all BTEX, followed by o-xylene and toluene with 16-23%, 35-41% and 57-69% biodegradation, respectively. Ethylbenzene was consistently the fastest BTEX chemical removed with 99% biodegradation for the four bioreactor acclimated biomasses tested. For the 1,200 ppm BTEX acclimated biomass, benzene showed the highest removal efficiency (99%) among the four biomass environmental conditions tested, along with 99% toluene and 99% ethylbenzene biodegradation. O-xylene showed 92-94% removal. In all bioassays tested Tergitol NP-10 was fully removed, and did not have a substantial effect on BTEX biodegradation at the end of a 10-day evaluation.

Bacteria, Aerobic↗
PubMedDate not supplied

Gasoline and vapor exposures in service station and leaking underground storage tank scenarios.

Exposure to gasoline and gasoline vapors from service station operations and leaking underground storage tanks is a major health concern. Six scenarios for human exposure were examined, based primarily on measured air and water concentrations of total hydrocarbons, benzene, xylenes, and toluene. Calculated mean and upper limit lifetime exposures provide a tool for assisting public health officials in assessing and managing gasoline-related health risks.

Air Pollutants, Occupational↗
PubMed2004

[Determination of sulfur compounds in fluid catalytic cracking gasoline by gas chromatography with a sulfur chemiluminescence detector].

A method for the separation and determination of sulfur compounds in fluid catalytic cracking gasoline (FCC gasoline) by gas chromatography with a sulfur chemiluminescence detector (GC-SCD) was established. Fifty eight sulfur compounds including mercaptan, sulfide, disulfide, thiophene, alkyl thiophenes, benzothiophene and alkyl benzothiophenes were identified based on their retention indexes and the data obtained from gas chromatography with an atomic emission detector (GC-AED). The effects of flow rate of carrier gas and oven temperature were discussed. Detection reproducibilities of main sulfur compounds (thiophene, n-butyl mercaptan, 2-methylthiophene, 3-methylthiophene, 2,4-dimethylthiophene) in FCC gasoline were satisfactory (RSDs were no more than 5.0%) and detection limit for sulfur was 0.1 mg/L. Using thiophene and benzothiophene as testing samples, it was determined that response factor was independent of the molecular structure of sulfur compounds. The linear range was 0.5-800.0 mg/L sulfur with a correlation coefficient of 0.999.

Catalysis↗
PubMed1985

[Comparative study of the behavior of particulate emissions from diesel and gasoline engines in animal lungs: elimination rate and induction of benzo(a)pyrene hydroxylase and ethoxycoumarin de-ethylase].

The emitted particulates of five diesel-engined and two gasoline-engined passenger cars were investigated for the elimination rate from hamster lungs after intratracheal instillation. In addition extracts of these particulates were studied for their influence on the mixed function oxidase activity (MFO; Benzo(a)pyrene Hydroxylase, Ethoxycoumarine Deethylase). Differences in the elimination rates of diesel soot and particulates from gasoline engines were not found. Compared with the blanc the extracts of diesel soot from two vehicles proved to give a moderate increase of the MFO activity, but a significant difference to the blanc was observed with the extracts of the gasoline engines. It should be mentioned that the effects were studied without taking into account the quantitative relations of the emissions in the ambient air. However, the amounts of particulates were extremely high in relation to the natural conditions. In the limits of our test model there is no indication of a higher toxicity of diesel-emissions.

7-Alkoxycoumarin O-Dealkylase↗
PubMed2001

Effect of Pentanol Partitioning on Solubilization of Tetrachloroethylene and Gasoline by Sodium Dodecyl Sulfate Micelles.

The effect of interfacial pentanol concentrations on solubilization of tetrachloroethylene (PCE) and gasoline by sodium dodecyl sulfate (SDS) micelles was compared to that for dodecane solubilization, which had been measured in a previous study. The solubilization of PCE and gasoline reached their maximum values at a 1 : 3 SDS-to-pentanol molar ratio in the interface. As pentanol concentrations increased beyond that necessary for interfacial saturation, solubilization of PCE and gasoline decreased. This behavior was similar to that observed when dodecane was the oil phase. Electrical conductivity of aqueous SDS/pentanol solutions followed a trend similar to that for oil solubilization, reaching a maximum value at a 1 : 3 molar ratio of SDS to pentanol in the interface. The results of this and previous studies suggest that pentanol partitioning in SDS micelles can be described by a simple two-region model: Region I is the interface between the water-continuous phase and oil and Region II is the micelle inner core. When the mole fraction of pentanol in the interface is less than 0.75, pentanol partitions strongly into Region I, where it acts as a cosurfactant along with SDS and enhances oil solubilization. Above 0.75 mole fraction in the interface, pentanol partitions strongly into Region II, where it acts as a polar oil and competes with other oils for solubilization. Copyright 2001 Academic Press.

Journal Article↗
PubMed1999

Metabolism of methyl tert-butyl ether and other gasoline ethers by human liver microsomes and heterologously expressed human cytochromes P450: identification of CYP2A6 as a major catalyst.

To reduce the production of carbon monoxide and other pollutants in motor vehicle exhaust, methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) are added to gasoline as oxygenates for more complete combustion. Previously, we demonstrated that human liver is active in metabolizing MTBE to tert-butyl alcohol (TBA) and that cytochrome P450 (CYP) enzymes play a critical role in the metabolism of MTBE. The present study demonstrates that human liver is also active in the oxidative metabolism of ETBE and TAME. A large interindividual variation in metabolizing these gasoline ethers was observed in 15 human liver microsomal samples. The microsomal activities in metabolizing MTBE, ETBE, and TAME were highly correlated among each other (r, 0.91-0. 96), suggesting that these ethers are metabolized by the same enzyme(s). Correlation analysis of the ether-metabolizing activities with individual CYP enzyme activities in the liver microsomes showed that the highest degree of correlation was with human CYP2A6 (r, 0. 90-0.95), which is constitutively expressed in human livers and known to be polymorphic. CYP2A6 displayed the highest turnover number in metabolizing gasoline ethers among a battery of human CYP enzymes expressed in human B-lymphoblastoid cells. Kinetic studies on MTBE metabolism with three human liver microsomes exhibited apparent Km values that ranged from 28 to 89 microM and the V(max) values from 215 to 783 pmol/min/mg, with similar catalytic efficiency values (7.7 to 8.8 microl/min/mg protein). Metabolism of MTBE, ETBE, and TAME by human liver microsomes was inhibited by coumarin, a known substrate of human CYP2A6, in a concentration-dependent manner. Monoclonal antibody against human CYP2A6 caused a significant inhibition (75% to 95%) of the metabolism of MTBE, ETBE, and TAME in human liver microsomes. Taken together, these results clearly indicate that in human liver, CYP2A6 is the major enzyme responsible for the metabolism of MTBE, ETBE, and TAME.

Aryl Hydrocarbon Hydroxylases↗
PubMed2004

Remote sensing of PM, NO, CO and HC emission factors for on-road gasoline and diesel engine vehicles in Las Vegas, NV.

A novel light detection and ranging-based remote sensing system was assembled and used to measure mass particulate matter (PM) emissions per unit of fuel burned from in-use on-road vehicles. A commercially available remote sensing system was concurrently used to measure emissions of carbon monoxide (CO), nitrogen oxide (NO) and hydrocarbons (HC). The two systems were used to measure 61,207 gasoline and 1180 diesel powered vehicle emissions in Las Vegas, NV from 4/4/2000 to 5/16/2002. Emission factors were related to vehicle age, weight class and fuel type by matching license IDs to the state registration data. Measurements of vehicle speed and acceleration permitted the analysis of emission factors by vehicle specific power (VSP). Average emission factors were calculated for light-duty (<3863 kg [8500 lbs]) gasoline vehicles (LDGV), light-duty diesel vehicles (LDDV), heavy-duty (>3863 kg [8500 lbs]) gasoline vehicles (HDGV) and heavy-duty diesel vehicles (HDDV). LDDV and HDDV emitted approximately 25 times more PM per mass of fuel than LDGV and HDGV. Sufficient numbers of LDGV were measured to relate VSP with CO, HC and NO emissions. No relationship was observed between PM emissions and VSP. PM emission factors from LDGV increased with vehicle age. Fuel-based emission factors measured by remote sensing were compared with MOBILE6 and PART5 emissions model factors. Good agreement was observed for HC emission factors for vehicles less than 20 years old. MOBILE6 CO emission factors were approximately 2 times greater than measured CO emission factors for vehicles less than 13 years old. Measured NO emission factors were approximately 50% greater than MOBILE6 factors for vehicles 7-15 years old but in good agreement for vehicles less than 7 years old. Measured PM emission factors showed a clear increase with vehicle age, however, PART5 uses only a single PM emission factor for LDGV less than 18 years old. The PM emission factors for the fleet of LDGV, HDGV, LDDV and HDDV were 0.06, 0.05, 1.6 and 1.5 g/kg, respectively.

Journal Article↗
PubMed2003

Detection of the gasoline components methyl tert-butyl ether, benzene, toluene, and m-xylene using ion mobility spectrometers with a radioactive and UV ionization source.

For the first time, ion mobility spectrometers (IMS) with radioactive and UV ionization sources in combination with multicapillary columns (MCCs) have been used to determine methyl tert-butyl ether (MTBE), a gasoline additive, in water and nitrogen as well as the monoaromatic compounds benzene, toluene, and m-xylene (BTX). A membrane extraction unit was set up to extract the substances from water, which is simple, effective, and easy to automate for further applications. Thus, the detection of MTBE and BTX of gasoline vapors was accomplished after a preliminary silicone membrane extraction. Two-dimensional data analyses of IMS-chromatograms allow us to separate these substances clearly according to their different retention and drift times. Method detection limits for MTBE were 2 microg/L (UV) and 30 pg/L (63Ni) in nitrogen and 20 mg/L (UV) and 1 microg/L (63Ni) in water. Rather a good reproducibility was achieved with relative standard deviations of between 2.9 and 9%. The method presented in this article has been proven to be suitable for nearly real-time monitoring as the total analysis time is less than 90 s. As an example of application, the detection of MTBE and BTX in a mixture of volatile organic compounds of pure gasoline using the 2-D IMS-chromatogram is presented.

Journal Article↗
PubMed2002

Relationship between environmental exposure to toluene, xylene and ethylbenzene and the expired breath concentrations for gasoline service workers.

This study evaluated the relationship between the breath concentrations of, and personal exposure to, toluene, xylene and ethylbenzene of thirty workers from ten gasoline stations. Personal exposure air samples and workplace samples were collected simultaneously. Each subject provided a sample of exhaled breath after his or her personal exposure air was sampled. Twenty-five personal air, 17 workplace and 30 breath samples were collected in this study. Results indicated that breath concentrations of toluene and xylene were significantly correlated with personal monitoring concentrations. Furthermore, multiple regression analysis showed that exhaled toluene levels were highly influenced by personal toluene concentrations and the amount of personal gasoline sold (r2 = 0.762), while exhaled xylene levels depended on wind speed and personal xylene exposure concentrations (r2 = 0.665). Exhaled ethylbenzene levels were too low to present a relationship between concentrations and personal exposure levels. The exhaled toluene, xylene and ethylbenzene concentrations ranged from 4.3 to 41.8, 0.9 to 13.9, and 0.2 to 6.5 ppb, and the corresponding personal monitoring concentrations ranged from 60.3 to 572.3, 16.4 to 156.6, and 10.7 to 136.6, respectively. The average number of symptoms per person, according to neurotoxic questionnaire 16 (abbreviated as Q16) was 4.1 and six workers showed over six symptoms in Q16. This study suggests that exhaled toluene and xylene levels are suitable for use as biological exposure indices even at the ppb-level of exposure. Gasoline service workers are exposed to high levels of volatile organic compounds (VOCs) and the potential threats to their neurological systems deserve further investigation.

Adult↗
PubMed1994

Detection of nitro-azabenzo[a]pyrene derivatives in the semivolatile phase originating from airborne particulate matter, diesel and gasoline vehicles.

Mutagens in the semivolatile phase of airborne particulate matter, diesel and gasoline engine emissions were investigated using chemical and biological assays. The previously unknown mutagens, 1-(3-)nitro-6-azabenzo[a]pyrenes (1-N-6-ABP and 3-N-6-ABP) and 1-(3-)nitro-6-azabenzo[a]pyrene-N-oxides (1-N-6-ABPO and 3-N-6-ABPO), were detected in the semivolatile phase, which was adsorbed onto XAD-4 resin combined with a Teflon-coated fibre filter. Dichloromethane extracts of materials adsorbed onto XAD-4 resin were divided into acidic, neutral and basic by liquid-liquid separation. These chemicals in the basic fraction were the major mutagens in the semivolatile phase when they were bioassayed using Salmonella typhimurium TA98 in the absence of S9 mix; the mutagenicity of the basic fraction contributed at the rate of 42.9-68.8% of that of crude extracts for airborne, diesel and gasoline emission materials. As the mutagens were found to be difficult to analyse by gas chromatography (because of their probable absorption onto the packing) they were purified by HPLC and analysed by mass spectrometry. The concentrations of 1-N-6-ABP, 3-N-6-ABP, 1-N-6-ABPO and 3-N-6-ABPO detected were 1.1, 1.2, 0.8 and 0.3 ng/g, respectively, of materials in the airborne sample, and 4.9, 7.7, 2.2 and 3.8 ng/g, respectively, of materials in the diesel emission. Only 1-N-6-ABP (3.4 ng/g) and 3-N-6-ABP (4.9 ng/g) were detected in the semivolatile phase of the gasoline engine emission.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗
PubMed2006

Gasoline exhaust emissions induce vascular remodeling pathways involved in atherosclerosis.

Epidemiological evidence indicates that environmental air pollutants are positively associated with the development of chronic vascular disease; however, the mechanisms involved have not been fully elucidated. In the present study we examined molecular pathways associated with chronic vascular disease in atherosclerosis-prone apolipoprotein E-deficient (ApoE(-/-)) mice, including markers of vascular remodeling and oxidative stress, in response to exposure to the ubiquitous environmental pollutant, gasoline engine emissions. ApoE(-/-) mice, on a high-fat diet, were exposed by inhalation to either filtered air; 8, 40, or 60 mug/m(3) particulate matter whole exhaust; or filtered exhaust with gases matching the 60-mug/m(3) concentration, for 7 weeks. Aortas and plasma were collected and assayed for changes in histochemical markers, real-time reverse transcriptase-polymerase chain reaction, and indicators of oxidative damage. Inhalational exposure to gasoline engine emissions resulted in increased aortic mRNA expression of matrix metalloproteinase-3 (MMP-3), MMP-7, and MMP-9, tissue inhibitor of metalloproteinases-2, endothelin-1 and heme oxygenase-1 in ApoE(-/-) mice; increased aortic MMP-9 protein levels were confirmed through immunohistochemistry. Elevated reactive oxygen species were also observed in arteries from exposed animals, despite absence of plasma markers. Similar findings were also observed in the aortas of ApoE(-/-) mice exposed to particle-filtered atmosphere, implicating the gaseous components of the whole exhaust in mediating the expression of markers associated with the vasculopathy. These findings demonstrate that exposure to gasoline engine emissions results in the transcriptional upregulation of factors associated with vascular remodeling, as well as increased markers of vascular oxidative stress, which may contribute to the progression of atherosclerosis and reduced stability of vulnerable plaques.

Air Pollutants↗
PubMed2000

Cometabolic biodegradation of methyl tert-butyl ether by a soil consortium: Effect of components present in gasoline.

A soil consortium was tested for its ability to degrade reformulated gasoline, containing methyl tert-butyl ether (MTBE). Reformulated gasoline was rapidly degraded to completion. However, MTBE tested alone was not degraded. A screening was carried out to identify compounds in gasoline that participate in cometabolism with MTBE. Aromatic compounds (benzene, toluene, xylenes) and compounds structurally similar to MTBE (tert-butanol, 2,2-dimethylbutane, 2,2,4-trimethylpentane) were unable to cometabolize MTBE. Cyclohexane was resistant to degradation. However, all n-alkanes tested for cometabolic activity (pentane, hexane, heptane) did enable the biodegradation of MTBE. Among the alkanes tested, pentane was the most efficient (200 &mgr;g/day). Upon the depletion of pentane, the consortium stopped degrading MTBE. When the consortium was spiked with pentane, MTBE degradation continued. When the ratio of MTBE to pentane was increased, the amount of MTBE degraded by the consortium was higher. Finally, diethylether was tested for cometabolic degradation with MTBE. Both compounds were degraded, but the process differed from that observed with pentane.

Journal Article↗
PubMed1997

[Observation on surface characters of particles emitted from gasoline and diesel motor vehicle].

Surface compositions and morphological features of particles emitted from gasoline and diesel motor vehicle in Taiyuan were observed by scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. The results showed that the surface of particles from gasoline motor vehicle contained larger amount of lead, amounting to 22.5% (average) among 15 elements measured; whereas the particles from diesel motor vehicle contained less lead, amounting to only 8%. But the size from diesel motor vehicle particle was smaller than those from gasoline motor vehicle, < or = 2 microns particles amounted to 73% and 62% of the total particles, respectively. The shapes of particles were irregular, with rough multiple-porous surface. The morphological features of particles from both motor vehicles were similar.

Particle Size↗
PubMed2002

[Alkene bromination used for detailed hydrocarbon and bulk hydrocarbon group-type analysis of gasolines containing alkenes].

The optimized reaction conditions of selective alkene bromination for gasolines containing aromatics and saturated hydrocarbons are presented. By this way, the interfering problem in alkene determination from coeluting saturated hydrocarbons has been solved. So the detailed hydrocarbon analysis can be improved by a simple system containing polar and non-polar columns or by a gas chromatograph coupled with an atomic emission detector (GC-AED). Under the optimized conditions, it was found that the alkene compounds were selectively and completely brominated but the aromatics and alkane compounds were remained unaffected. A simple treatment, 90 s-120 s for reaction and 10 s-20 s for removing the excess bromine, can be easily realized. The treatment is applied for the different types of gasoline containing 0-100% alkene. Besides, one of the most important applications of this treatment is to analyse the hydrocarbons in detail from the fluid catalytic cracking (FCC) gasoline. The samples in these cases may not be accurately analyzed when using the traditional method of hydrocarbon analysis because of the presence of coeluted interfering olefins above C7.

English Abstract↗