Characterisation of single particles from in-port ship emissions

Emissions from shipping traffic may impact severely upon air quality in port cities. In this study, the size and composition of freshly emitted individual ship exhaust particles has been investigated using an aerosol time-of-flight mass spectrometer (ATOFMS) co-located with a suite of real-time instrumentation at a site in the Port of Cork, Ireland. The collected spectra were clustered using the K-means algorithm and a unique ship exhaust class containing internally mixed elemental and organic carbon, sodium, calcium, iron, vanadium, nickel and sulfate was identified. Over twenty sharp emission events were observed for this particle type during the three week measurement period in August 2008. Coincident increases in mass concentrations of sulfate, elemental carbon and particles below 2.5 μm in diameter (PM_2.5) were also observed during these events. Simultaneous scanning mobility particle sizer (SMPS) measurements indicate that the vast majority of freshly emitted ship exhaust particles lie in the ultrafine mode (<100 nm diameter). A second particle class consisted of internally mixed organic carbon, elemental carbon, ammonium and sulfate, and is tentatively attributed to aged or regionally transported ship exhaust. The results suggest that ATOFMS single particle mass spectra, when used in conjunction with other air quality monitoring instrumentation, may be useful in determining the contribution of local shipping traffic to air quality in port cities.     

Ship emissions and their externalities for Greece

The existing and emerging international and European policy framework for the reduction of ship exhaust emissions dictates the need to produce reliable national, regional and global inventories in order to monitor emission trends and consequently provide the necessary support for future policy making. Furthermore, the inventories of ship exhaust emissions constitute the basis upon which their external costs are estimated in an attempt to highlight the economic burden they impose upon the society and facilitate the cost–benefit analysis of the proposed emission abatement technologies, operational measures and market-based instruments prior to their implementation.The case of Greece is of particular interest mainly because the dense ship traffic within the Greek seas directly imposes the impact of its exhaust emission pollutants (NO_x, SO₂ and PM) upon the highly populated, physically sensitive and culturally precious Greek coastline, as well as upon the land and seas of Greece in general, whereas the contribution of Greece in the global CO₂ inventory at a time of climatic change awareness cannot be ignored. In this context, this paper presents the contribution of Greece in ship exhaust emissions of CO₂, NO_x, SO₂ and PM from domestic and international shipping over the last 25 years (1984–2008), utilizing the fuel-based (fuel sales) emission methodology. Furthermore, the ship exhaust emissions generated within the Greek seas and their externalities are estimated for the year 2008, through utilizing the fuel-based (fuel sales) approach for domestic shipping and the activity-based (ship traffic) approach for international shipping.On this basis, it was found that during the 1984 to 2008 period the fuel-based (fuel sales) ship emission inventory for Greece increased at an average annual rate of 2.85%. In 2008, the CO₂, NO_x, SO₂ and PM emissions reached 12.9 million tons (of which 12.4 million tons of CO₂) and their externalities were found to be around 3.1 billion euro. With regard to shipping within the Greek seas, the utilization of the fuel-based (fuel sales) analysis for domestic shipping and the activity-based (ship traffic) analysis for international shipping shows that the ship-generated emissions reached 7.4 million tons (of which 7 million tons of CO₂) and their externalities were estimated at 2.95 billion euro. Finally, the internalization of external costs for domestic shipping was found to produce an increase of 12.96 and 2.71 euro per passenger and transported ton, respectively.     

Evaluation of retrofit crankcase ventilation controls and diesel oxidation catalysts for reducing air pollution in school buses

This study evaluates the effect of retrofit closed crankcase ventilation filters (CCFs) and diesel oxidation catalysts (DOCs) on the in-cabin air quality in transit-style diesel school buses. In-cabin pollution levels were measured on three buses from the Pueblo, CO District 70 fleet. Monitoring was conducted while buses were driven along their regular routes, with each bus tested three times before and three times after installation of control devices. Ultrafine number concentrations in the school bus cabins were 33–41% lower, on average, after the control devices were installed. Mean mass concentrations of particulate matter less than 2.5 μm in diameter (PM2.5) were 56% lower, organic carbon (OC) 41% lower, elemental carbon (EC) 85% lower, and formaldehyde 32% lower after control devices were installed. While carbon monoxide concentrations were low in all tests, mean concentrations were higher after control devices were installed than in pre-retrofit tests. Reductions in number, OC, and formaldehyde concentrations were statistically significant, but reductions in PM2.5 mass were not. Even with control devices installed, during some runs PM2.5 and OC concentrations in the bus cabins were elevated compared to ambient concentrations observed in the area. OC concentrations inside the bus cabins ranged from 22 to 58 μg m^?3 before and 13 to 33 μg m^?3 after control devices were installed. OC concentrations were correlated with particle-bound organic tracers for lubricating oil emissions (hopanes) and diesel fuel and tailpipe emissions (polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons). Mean concentrations of hopanes, PAH, and aliphatic hydrocarbons were lower by 37, 50, and 43%, respectively, after the control devices were installed, suggesting that both CCFs and DOCs were effective at reducing in-cabin OC concentrations.     

Effects of biodiesel on emissions of regulated air pollutants and polycyclic aromatic hydrocarbons under engine durability testing

An 80,000-km durability test was performed on two engines using diesel and biodiesel (methyl ester of waste cooking oil) as fuel in order to examine emissions resulting from the use of biodiesel. The test biodiesel (B20) was blended with 80% diesel and 20% methyl ester derived from waste cooking oil. Emissions of regulated air pollutants, including CO, HC, NO_x, particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) were measured at 20,000-km intervals. The identical-model engines were installed on a standard dynamometer equipped with a dilution tunnel used to measure the pollutants. To simulate real-world driving conditions, emission measurements were made in accordance with the United States Environmental Protection Agency (USEPA) FTP transient cycle guidelines. At 0 km of the durability test, HC, CO and PM emission levels were lower for the B20 engine than those for diesel. After running for 20,000 km and longer, they were higher. However, the deterioration coefficients for these regulated air pollutants were not statistically higher than 1.0, implying that the emission factors do not increase significantly after 80,000 km of driving. Total (gaseous+particulate phase) PAH emission levels for both B20 and diesel decreased as the driving mileage accumulated. However, for the engine using B20 fuel, particulate PAH emissions increased as engine mileage increased. The average total PAH emission factors were 1097 and 1437 μg bhp h⁻¹ for B20 and diesel, respectively. For B20, the benzo[a]pyrene equivalence emission factors were 0.77, 0.24, 0.20, 7.48, 5.43 and 14.1 μg bhp h⁻¹ for 2-, 3-, 4-, 5-, 6-ringed and total PAHs. Results show that B20 use can reduce both PAH emission and its corresponding carcinogenic potency.     

Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health

ABSTRACT

Particulate matter (PM) emissions from stationary combustion sources burning coal, fuel oil, biomass, and waste, and PM from internal combustion (IC) engines burning gasoline and diesel, are a significant source of primary particles smaller than 2.5 μm (PM_2.5) in urban areas. Combustion-generated particles are generally smaller than geologically produced dust and have unique chemical composition and morphology. The fundamental processes affecting formation of combustion PM and the emission characteristics of important applications are reviewed. Particles containing transition metals, ultrafine particles, and soot are emphasized because these types of particles have been studied extensively, and their emissions are controlled by the fuel composition and the oxidant-tem-perature-mixing history from the flame to the stack. There is a need for better integration of the combustion, air pollution control, atmospheric chemistry, and inhalation health research communities. Epidemiology has demonstrated that susceptible individuals are being harmed by ambient PM. Particle surface area, number of ultrafine particles, bioavailable transition metals, polycyclic aromatic hydrocarbons (PAH), and other particle-bound organic compounds are suspected to be more important than particle mass in determining the effects of air pollution. Time- and size-resolved PM measurements are needed for testing mechanistic toxicological hypotheses, for characterizing the relationship between combustion operating conditions and transient emissions, and for source apportionment studies to develop air quality plans. Citations are provided to more specialized reviews, and the concluding comments make suggestions for further research.     

Study of Miller timing on exhaust emissions of a hydrotreated vegetable oil (HVO)-fueled diesel engine

The effect of intake valve closure (IVC) timing by utilizing Miller cycle and start of injection (SOI) on particulate matter (PM), particle number, and nitrogen oxide (NO_x) emissions was studied with a hydrotreated vegetable oil (HVO)-fueled nonroad diesel engine. HVO-fueled engine emissions, including aldehyde and polyaromatic hydrocarbon (PAH) emissions, were also compared with those emitted with fossil EN590 diesel fuel. At the engine standard settings, particle number and NO_x emissions decreased at all the studied load points (50%, 75%, and 100%) when the fuel was changed from EN590 to HVO. Adjusting IVC timing enabled a substantial decrease in NO_x emission and combined with SOI timing adjustment somewhat smaller decrease in both NO_x and particle emissions at IVC??50 and??70 °CA points. The HVO fuel decreased PAH emissions mainly due to the absence of aromatics. Aldehyde emissions were lower with the HVO fuel with medium (50%) load. At higher loads (75% and 100%), aldehyde emissions were slightly higher with the HVO fuel. However, the aldehyde emission levels were quite low, so no clear conclusions on the effect of fuel can be made. Overall, the study indicates that paraffinic HVO fuels are suitable for emission reduction with valve and injection timing adjustment and thus provide possibilities for engine manufacturers to meet the strictening emission limits.

Implications: NO_x and particle emissions are dominant emissions of diesel engines and vehicles. New, biobased paraffinic fuels and modern engine technologies have been reported to lower both of these emissions. In this study, even further reductions were achieved with engine valve adjustment combined with novel hydrotreated vegetable oil (HVO) diesel fuel. This study shows that new paraffinic fuels offer further possibilities to reduce engine exhaust emissions to meet the future emission limits.

Supplementary Materials: Supplementary materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for a complete list of analysed PAH compounds.     

Current and future emission estimates of exhaust gases and particles from shipping at the largest port in Korea

The emissions of exhaust gases (NO _x , SO₂, VOCs, and CO₂) and particles (e.g., PM) from ships traversing Busan Port in Korea were estimated over three different years (the years 2006, 2008, and 2009). This analysis was performed according to the ship operational modes (“at sea,” “maneuvering,” and “in port”) and ship types based on an activity-based method. The ship emissions for current (base year 2009) and future scenarios (years 2020 and 2050) were also compared. The annual emissions of SO₂, VOCs, PM, and CO₂ were highest (9.6?×?10³, 374, 1.2?×?10³, and 5.6?×?10⁵ ton year^?1, respectively) in 2008. In contrast, the annual NO _x emissions were highest (11.7?×?10³ ton year^?1) in 2006 due mainly to the high NO _x emission factor. The emissions of air pollutants for each ship operational mode differed considerably, with the largest emission observed in “in port” mode. In addition, the largest fraction (approximately 45–67 %) of the emissions of all air pollutants during the study period was emitted from container ships. The future ship emissions of most pollutants (except for SO₂ and PM) in 2020 and 2050 are estimated to be 1.4–1.8 and 4.7–6.1 times higher than those in 2009 (base year), respectively.     

Effects of meteorology on diurnal and nocturnal levels of priority polycyclic aromatic hydrocarbons and elemental and organic carbon in PM10 at a source and a receptor area in Mexico City

PM₁₀ levels of the 16 US-EPA Priority Pollutant polycyclic aromatic hydrocarbons (PAHs) were measured from March 17 to 31, 2003, in 8-h time bins (morning, afternoon and nighttime) at Merced, a source site dominated by vehicular traffic emissions near the center of Mexico City, and at Pedregal, a receptor area located downwind in a residential area of low traffic. Along with PAH, elemental (EC) and organic carbon (OC), mass, and prevailing meteorological parameters were measured. At the source location, measured concentrations of benzo[a]pyrene (BAP), an agent suspected of being carcinogenic to humans and of causing oxidative DNA damage, reached concentrations as high as 2.04 and 2.11 ng m^?3 during the morning of a weekday and the night period of a holiday. Compared with source dominated areas in Central Los Angeles, the BAP levels found in Central Mexico City are approximately 6 times higher. Benzo[ghi]perylene (BGP) levels were, in general, the highest among the target PAH, both at the source (7.2 ng m^?3) and the receptor site (2.8 ng m^?3), suggesting that, at both locations, exhaust emission by light-duty (LD) vehicles is an important contributor to the atmospheric PAH burden. Higher PAH concentrations were observed during the morning period (5:00–13:00 h) at the source and the receptor site. The concentrations of PAHs found predominantly in the particle-phase (MW > 202) correlated well (r = 0.57–0.71) with the occurrence of surface thermal inversions and with mixing heights (r = ?0.57 to ?0.72). Organic and elemental carbon ratios also indicated that Pedregal is impacted by secondary aerosols during the afternoon hours.     

Comparison of particle emissions from small heavy fuel oil and wood-fired boilers

Flue gas emissions of wood and heavy fuel oil (HFO) fired district heating units of size range 4–15 MW were studied. The emission measurements included analyses of particle mass, number and size distributions, particle chemical compositions and gaseous emissions. Thermodynamic equilibrium calculations were carried out to interpret the experimental findings.In wood combustion, PM1 (fine particle emission) was mainly formed of K, S and Cl, released from the fuel. In addition PM1 contained small amounts of organic material, CO₃, Na and different metals of which Zn was the most abundant. The fine particles from HFO combustion contained varying transient metals and Na that originate from the fuel, sulphuric acid, elemental carbon (soot) and organic material. The majority of particles were formed at high temperature (>800 °C) from V, Ni, Fe and Na. At the flue gas dew point (125 °C in undiluted flue gas) sulphuric acid condensed forming a liquid layer on the particles. This increases the PM1 substantially and may lead to partial dissolution of the metallic cores.Wood-fired grate boilers had 6–21-fold PM1 and 2–23-fold total suspended particle (TSP) concentrations upstream of the particle filters when compared to those of HFO-fired boilers. However, the use of single field electrostatic precipitators (ESP) in wood-fired grate boilers decreased particle emissions to same level or even lower as in HFO combustion. On the other hand, particles released from the HFO boilers were clearly smaller and higher in number concentration than those of wood boilers with ESPs. In addition, in contrast to wood combustion, HFO boilers produce notable SO₂ emissions that contribute to secondary particle formation in the atmosphere. Due to vast differences in concentrations of gaseous and particle emissions and in the physical and chemical properties of the particles, HFO and wood fuel based energy production units are likely to have very different effects on health and climate.     

Chemical composition of PM10 and PM2.5 collected at ground level and 100 meters during a strong winter-time pollution episode in Xi'an, China

An intensive sampling of aerosol particles from ground level and 100 m was conducted during a strong pollution episode during the winter in Xi'an, China. Concentrations of water-soluble inorganic ions, carbonaceous compounds, and trace elements were determined to compare the composition of particulate matter (PM) at the two heights. PM mass concentrations were high at both stations: PM10 (PM with aerodynamic diameter < or =10 microm) exceeded the China National Air Quality Standard Class II value on three occasions, and PM2.5 (PM with aerodynamic diameter < or =2.5 microm) exceeded the daily U.S. National Ambient Air Quality Standard more than 10 times. The PM10 organic carbon (OC) and elemental carbon (EC) were slightly lower at the ground than at 100 m, both in terms of concentration and percentage of total mass, but OC and EC in PM2.5 exhibited the opposite pattern. Major ionic species, such as sulfate and nitrate, showed vertical variations similar to the carbonaceous aerosols. High sulfate concentrations indicated that coal combustion dominated the PM mass both at the ground and 100 m. Correlations between K+ and OC and EC at 100 m imply a strong influence from suburban biomass burning, whereas coal combustion and motor vehicle exhaust had a greater influence on the ground PM. Stable atmospheric conditions apparently led to the accumulation of PM, especially at 100 m, and these conditions contributed to the similarities in PM at the two elevations. Low coefficient of divergence (CD) values reflect the similarities in the composition of the aerosol between sites, but higher CDs for fine particles compared with coarse ones were consistent with the differences in emission sources between the ground and 100 m.     

Transport impacts on atmosphere and climate: Shipping

Emissions of exhaust gases and particles from oceangoing ships are a significant and growing contributor to the total emissions from the transportation sector. We present an assessment of the contribution of gaseous and particulate emissions from oceangoing shipping to anthropogenic emissions and air quality. We also assess the degradation in human health and climate change created by these emissions. Regulating ship emissions requires comprehensive knowledge of current fuel consumption and emissions, understanding of their impact on atmospheric composition and climate, and projections of potential future evolutions and mitigation options. Nearly 70% of ship emissions occur within 400 km of coastlines, causing air quality problems through the formation of ground-level ozone, sulphur emissions and particulate matter in coastal areas and harbours with heavy traffic. Furthermore, ozone and aerosol precursor emissions as well as their derivative species from ships may be transported in the atmosphere over several hundreds of kilometres, and thus contribute to air quality problems further inland, even though they are emitted at sea. In addition, ship emissions impact climate. Recent studies indicate that the cooling due to altered clouds far outweighs the warming effects from greenhouse gases such as carbon dioxide (CO₂) or ozone from shipping, overall causing a negative present-day radiative forcing (RF). Current efforts to reduce sulphur and other pollutants from shipping may modify this. However, given the short residence time of sulphate compared to CO₂, the climate response from sulphate is of the order decades while that of CO₂ is centuries. The climatic trade-off between positive and negative radiative forcing is still a topic of scientific research, but from what is currently known, a simple cancellation of global mean forcing components is potentially inappropriate and a more comprehensive assessment metric is required. The CO₂ equivalent emissions using the global temperature change potential (GTP) metric indicate that after 50 years the net global mean effect of current emissions is close to zero through cancellation of warming by CO₂ and cooling by sulphate and nitrogen oxides.     

Comprehensive primary particulate organic characterization of vehicular exhaust emissions in France

A study to characterize primary particulate matter (PM_2.5 and PM₁₀) from the French vehicular fleet was conducted during winter 2008, in a tunnel in Marseille, France. The carbonaceous fraction represents 70% of the aerosol mass and elemental carbon fraction (EC) represent 60% of the carbonaceous fraction. The organic carbon OC was characterized in term of its water soluble fraction, functionalization rate and HULIS content. Seventy trace organic compounds including alkanes, polycyclic aromatic hydrocarbons (PAH), petroleum biomarkers and carboxylic acids were also quantified, in order to determine an organic emission profile for chemical mass balance modeling studies. Such source profiles were still missing in Europe and particularly in France. The profile obtained in this study is consistent with profiles determined in tunnel or dynamometer studies performed in other countries during the last ten years. These results suggest that organic compounds profiles from vehicular exhaust emissions are not significantly influenced by the geographic area and are thus suitable for use in aerosol source apportionment modeling applied across extensive regions. The chemical profile determined here is very similar to those obtained for diesel emissions with high concentrations of EC relative to OC (EC/OC = 1.8) and low concentrations of the higher molecular weight PAH. These results are consistent with the high proportion of diesel vehicles in the French fleet (49%).     

Monitoring of sources and atmospheric processes controlling air quality in an urban Mediterranean environment

Different monitoring parameters (PM mass concentrations, number–size distribution, black carbon, gaseous pollutants, and chemical composition, among others) are currently used in air quality studies. Urban aerosols are the result of several sources and atmospheric processes, which suggests that a single monitoring technique is insufficient to quantitatively evaluate all of them.This study assesses the suitability of a number of monitoring techniques (PM mass concentrations, number and size distribution of ultra-fine particles, levels of gaseous pollutants, and a complete chemical characterization of PM₁₀ and PM_2.5) by examining the response of those techniques to the different emission sources and/or atmospheric processes affecting an urban Mediterranean area (Barcelona, NE Spain).The results of this work reveal that the PM mass, the number concentration and the chemical composition give different, but complementary, information. Whereas the mineral matter, a key atmospheric aerosol component across the Mediterranean, is not properly quantitatively assessed by measuring sub-micrometric particles, the monitoring of the number concentration is indispensable to interpret the origin of specific aerosol episodes. Furthermore, the chemical composition yields very relevant information to deduce the causes of specific pollution episodes.The number concentration of ultra-fine particles in urban areas is strongly dependent upon vehicle exhaust emissions, which may cause adverse health impacts. Moreover, urban Mediterranean environments are favourable to produce nucleation-mode particles (<20 nm) with photochemical origin. In those cases, these particles are expected to be of high solubility and consequently their toxicity may differ from that of traffic-generated ultra-fine particles. Thus, the use of a single monitoring parameter to evaluate the health effects seems to be not enough.     

Large PAHs detected in fine particulate matter emitted from light-duty gasoline vehicles

Emission factors of large PAHs with 6–8 aromatic rings with molecular weights (MW) of 300–374 were measured from 16 light-duty gasoline-powered vehicles (LDGV) and one heavy-duty diesel-powered vehicle (HDDV) operated under realistic driving conditions. LDGVs emitted PAH isomers of MW 302, 326, 350, and 374, while the HDDV did not emit these compounds. This suggests that large PAHs may be useful tracers for the source apportionment of gasoline-powered motor vehicle exhaust in the atmosphere. Emission rates of MW 302, 326, and 350 isomers from LDGVs equipped with three-way catalysts (TWCs) ranged from 2 to 10 (μg L⁻¹ fuel burned), while emissions from LDGVs classified as low emission vehicles (LEVs) were almost a factor of 10 lower. MW 374 PAH isomers were not quantified due to the lack of a quantification-grade standard. The reduced emissions associated with the LEVs are likely attributable to improved vapor recovery during the “cold-start” phase of the Federal Test Procedure (FTP) driving cycle before the catalyst reaches operating temperature. Approximately 2 (μg g⁻¹ PM) of MW 326 and 350 PAH isomer groups were found in the National Institute of Standards and Technology standard reference material (SRM)#1649 (Urban Dust). The pattern of the MW 302, 326, and 350 isomers detected in SRM#1649 qualitatively matched the ratio of these compounds detected in the exhaust of TWC LDGVs suggesting that each gram of Urban Dust SRM contained 5–10 mg of PM originally emitted from gasoline-powered motor vehicles.Large PAHs made up 24% of the total LEV PAH emissions and 39% of the TWC PAH emissions released from gasoline-powered motor vehicles. Recent studies have shown certain large PAH isomers have greater toxicity than benzo[a]pyrene. Even though the specific toxicity measurements on PAHs with MW >302 have yet to be performed, the detection of significant amounts of MW 326 and 350 PAHs in motor vehicle exhaust in the current study suggests that these compounds may pose a significant public health risk.     

Revised estimates of construction activity and emissions: Effects on ozone and elemental carbon concentrations in southern California

Emissions from diesel-powered construction equipment are an important source of nitrogen oxides (NO_x) and particulate matter (PM). A new emission inventory for construction equipment emissions is developed based on surveys of diesel fuel use; the revised inventory is compared to current emission inventories. California's OFFROAD model estimates are 4.5 and 3.1 times greater, for NO_x and PM respectively, than the fuel-based estimates developed here. The most relevant uncertainties are the overall amount of construction activity/diesel fuel use, exhaust emission factors for PM and NO_x, and the spatial allocation of emissions to county level and finer spatial scales. Construction permit data were used in this study to estimate spatial distributions of emissions; the resulting distribution is well correlated with population growth. An air quality model was used to assess the impacts of revised emission estimates. Increases of up to 15 ppb in predicted peak ozone concentrations were found in southern California. Elemental carbon and fine particle mass concentrations were in better agreement with observations using revised emission estimates, whereas negative bias in predictions of ambient NO_x concentrations increased.     

Hydrocarbon emission fingerprints from contemporary vehicle/engine technologies with conventional and new fuels

The present paper presents results from the analysis of 29 individual C₂–C₉ hydrocarbons (HCs) specified in the European Commission Ozone Directive. The 29 HCs are measured in exhaust from common, contemporary vehicle/engine/fuel technologies for which very little or no data is available in the literature. The obtained HC emission fingerprints are compared with fingerprints deriving from technologies that are being phased out in Europe. Based on the total of 138 emission tests, thirteen type-specific fingerprints are extracted (Mean ± SD percentage contributions from individual HCs to the total mass of the 29 HCs), essential for receptor modelling source apportionment. The different types represent exhaust from Euro3 and Euro4 light-duty (LD) diesel and petrol-vehicles, Euro3 heavy-duty (HD) diesel exhaust, and exhaust from 2-stroke preEuro, Euro1 and Euro2 mopeds. The fuels comprise liquefied petroleum gas, petrol/ethanol blends (0–85% ethanol), and mineral diesel in various blends (0–100%) with fatty acid methyl esters, rapeseed methyl esters palm oil methyl esters, soybean oil methyl or sunflower oil methyl esters. Type-specific tracer compounds (markers) are identified for the various vehicle/engine/fuel technologies.An important finding is an insignificant effect on the HC fingerprints of varying the test driving cycle, indicating that combining HC fingerprints from different emission studies for receptor modelling purposes would be a robust approach.The obtained results are discussed in the context of atmospheric ozone formation and health implications from emissions (mg km^?1 for LD and mopeds and mg kW h^?1 for HD, all normalised to fuel consumption: mg dm^?3 fuel) of the harmful HCs, benzene and 1,3-butadiene.Another important finding is a strong linear correlation of the regulated “total” hydrocarbon emissions (tot-HC) with the ozone formation potential of the 29 HCs (ΣPO₃ = (1.66 ± 0.04) × tot-RH; r² = 0.93). Tot-HC is routinely monitored in emission control laboratories, whereas C₂–C₉ are not. The revealed strong correlations broadens the usability of data from vehicle emission control laboratories and facilitates the comparison of the ozone formation potential of HCs in exhaust from of old and new vehicle/engine/fuel technologies.     

Real life evaluation of the emission reduction potential of a city bus retrofitted with a continuous regenerating trap

A cost effective measure to reduce particulate matter (PM) emissions of city buses is retrofitting with a continuous regenerating trap (CRT). In this paper, the performance of the CRT is evaluated in real life conditions using an on-the-road emission and energy measurement system developed previously in our laboratory.The CRT is found to reduce PM emissions to over 90% thereby also reducing CO and THC to at least 65%. No significant NO_x change is detected. The raise in fuel consumption is not significant. The exhaust gas temperature at the CRT is over 250 °C for 70% of the time thus easily fulfilling the manufacturer's demand. The demand for a NO_x/PM ratio of 15 is at least realised during 70% of the time.Follow-up measurements after 1 year showed no deterioration of the CRT.     

Emission rates and comparative chemical composition from selected in-use diesel and gasoline-fueled vehicles

Emission samples for toxicity testing and detailed chemical characterization were collected from a variety of gasoline- and diesel-fueled in-use vehicles operated on the Unified Driving Cycle on a chassis dynamometer. Gasoline vehicles included normal particle mass (particulate matter [PM]) emitters (tested at 72 and 30 degrees F), "black" and "white" smokers, and a new-technology vehicle (tested at 72 degrees F). Diesel vehicles included current-technology vehicles (tested at 72 and 30 degrees F) and a high PM emitter. Total PM emission rates ranged from below 3 mg/mi up to more than 700 mg/mi for the white smoker gasoline vehicle. Emission rates of organic and elemental carbon (OC/EC), elements (metals and associated analytes), ions, and a variety of particulate and semi-volatile organic compounds (polycyclic aromatic hydrocarbons [PAH], nitro-PAH, oxy-PAH, hopanes, and steranes) are reported for these vehicles. Speciated organic analysis also was conducted on the fuels and lube oils obtained from these vehicles after the emissions testing. The compositions of emissions were highly dependent on the fuel type (gasoline vs. diesel), the state of vehicle maintenance (low, average, or high emitters; white or black smokers), and ambient conditions (i.e., temperature) of the vehicles. Fuel and oil analyses from these vehicles showed that oil served as a repository for combustion byproducts (e.g., PAH), and oil-burning gasoline vehicles emitted PAH in higher concentrations than did other vehicles. These PAH emissions matched the PAH compositions observed in oil.     

Organic aerosol source apportionment from highly time-resolved molecular composition measurements

Organic molecular composition measurements with 3.5 min time resolution were performed with the photoionization aerosol mass spectrometer (PIAMS) over an 18-day period in October–November 2007 in Wilmington, Delaware, USA. Mass spectra were obtained for a total of 6244 time periods, and the signal intensities of 60 specific m/z ratios corresponding to key organic molecular species were modeled by positive matrix factorization (PMF). Six factors were identified that could be tentatively linked to specific sources (diesel exhaust, car emissions/road dust, meat cooking) or types of compounds (alkanes/alkanoic acids, phthalates, PAHs). Owing to the inherent high time resolution of PIAMS, the temporal (diurnal) and wind direction dependencies of these factors could be examined in detail to assess the impacts of point sources and atmospheric processes. Time-resolved EC/OC and gas-phase data (O₃, NO_x, CO) were also obtained during the measurement period to help distinguish primary (POC) and secondary (SOC) organic carbon. The total organic carbon (TOC) concentration averaged 2.6 μg m^?3 during the measurement period and most (>90%) was classified as primary. Of this, approximately one-third could be assigned as combustion POC and the other two-thirds as non-combustion POC. The PMF results were combined with EC/OC data for source apportionment. The diesel and car/road dust factors together represented about two-thirds of TOC, while the alkane/alkanoic acid and meat cooking factors contributed most of the remaining one-third. The phthalate and PAH factors contributed very little, only a few percent of the total. The diesel factor correlated most strongly to combustion POC, while the sum of the remaining factors correlated well with non-combustion POC.     

Emission profile of 18 carbonyl compounds,CO, CO2, and NOx emitted by a diesel engine fuelled with diesel and ternary blends containing diesel,ethanol and biodiesel or vegetable oils

The impact of vehicular emissions on air depends, among other factors, on the composition of fuel and the technology used to build the engines. The reduction of vehicular emissions requires changes in the fuel composition, and improving the technologies used in the manufacturing of engines and for the after-treatment of gases. In general, improvements to diesel engines have targeted not only emission reductions, but also reductions in fuel consumption. However, changes in the fuel composition have been shown to be a more rapid and effective alternative to reduce pollution. Some factors should been taken into consideration when searching for an alternative fuel to be used in diesel engines, such as emissions, fuel stability, availability and its distribution, as well as its effects on the engine durability. In this work, 45 fuel blends were prepared and their stability was evaluated. The following mixtures (v/v/v) were stable for the 90-day period and were used in the emission study: diesel/ethanol – 90/10%, diesel/ethanol/soybean biodiesel – 80/15/5%, diesel/ethanol/castor biodiesel – 80/15/5%, diesel/ethanol/residual biodiesel – 80/15/5%, diesel/ethanol/soybean oil – 90/7/3%, and diesel/ethanol/castor oil – 90/7/3%. The diesel/ethanol fuel showed higher reduction of NO_x emission at a lower load (2 kW) when compared with pure diesel. The other fuels showed a decrease of NO_x emissions in the ranges of 6.9–75% and 4–85% at 1800 rpm and 2000 rpm, respectively. The combustion efficiencies of the diesel can be enhanced by the addition of the oxygenate fuels, like ethanol and biodiesel/vegetable oil, resulting in a more complete combustion in terms of NO_x emission. In the case of CO₂ the decreases were in the ranges of 5–24% and 4–6% at 1800 rpm and 2000 rpm, respectively. Meanwhile, no differences were observed in CO emission. The carbonyl compounds (CC) studied were formaldehyde, acetaldehyde, propionaldehyde, acrolein, acetone, crotonaldehyde, butyraldehyde, butanone, benzaldehyde, isovaleraldehyde, valeraldehyde, o-toluenaldehyde, m-toluenaldehyde, p-toluenaldehyde, hexaldehyde, octaldehyde, 2,5-dimethylbenzaldehyde, and decaldehyde. Among them, formaldehyde, acetaldehyde, acetone, and propionaldehyde showed the highest emission concentrations. When ternary blend contains vegetable oil, there is a strong tendency to increase the emissions of the high weight CC and decrease the emissions of the low weight CC. The highest concentration of acrolein was observed when the fuel contains diesel, ethanol and biodiesel. With the exception of NO_x, the use of ternary blended fuels resulted on the increase in the emission rates of the studied compounds.