Emission Factors Of Organic Carbon Research Articles

On-board measurements of OC/EC ratio, mixing state, and light absorption of ship-emitted particles

Carbonaceous aerosols play important roles in environmental impacts and climate effects. The characteristics of ship-emitted carbonaceous aerosols keep unclear under the latest global low sulfur fuel oil policy. This study selected four ocean-going vessels burning low sulfur fuel oils for on-board exhaust testing. The emission factors of ship carbonaceous aerosols were obtained under different engine types (main and auxiliary engines), fuel types, and engine loads. Our results showed that fuel and engine types were both important factors affecting carbonaceous aerosol emissions for ship engines. The emission factors of OC and EC from main engines were 1.18 ± 0.62 and 0.06 ± 0.04 g/kg burning heavy fuel oil (HFO), while 0.52 ± 0.35 and 0.04 ± 0.03 g/kg burning marine gas oil (MGO), respectively. The OC/EC ratios of ship-emitted particles were within a large range of 2 to 23. The OC/EC ratios from the main engines were significantly higher than those from the auxiliary engines by a factor of 6.3. The result of chemical mixing states of ship-emitted particles observed by a single particle mass spectrometer (SPAMS) showed that OC and EC were internally mixed and existed as the ECOC-bonded forms in single particles. The measured light absorption of ship-emitted particles with higher OC/EC ratios showed an evident short-wave absorption enhancement based on the aethalometer AE-33. Our results implied that ship-emitted carbonaceous aerosols (especially with high OC/EC ratios) could not be uniformly treated regarding the optical properties to more precisely estimate their potential environmental impacts and climate effects in model systems in the future.

Emission Factors of Carbonaceous Aerosol and Stable Carbon Isotope for In-use Vehicles

Vehicle exhaust is an important anthropogenic source of atmospheric carbonaceous aerosols; of which, the emission factors and stable carbon isotope composition are important basic data. In-use motor vehicles of different types were selected to conduct dynamometer tests using different test cycles and under cold/hot start conditions. The exhaust of each test stage was collected to analyze the carbonaceous components and stable carbon isotopes and to discuss the influencing factors. The total carbon emission factors follow the order:heavy-duty diesel vehicles>light-duty diesel vehicles>light-duty gasoline vehicles. Although the emission factors of light-duty natural gas vehicles were very low at the low- and medium-speed stages, they were similar to those of heavy-duty diesel vehicles at the high-speed stage. The emission factors of cold start were higher than those of hot start, and the emission factors of the NEDC test cycle were lower than those of WLTC (which should be related to the driving speed). The emission factors of organic carbon (OC) of gasoline and natural gas vehicles were much higher than those of elemental carbon (EC) in every test stage. The emission factors of OC and EC of diesel vehicles were similar. The OC/EC of all types of vehicles increased with the increase in driving speed. Stable carbon isotopes in EC were higher than those in OC. The stable carbon isotope in different vehicles follow the order:light-duty gasoline vehicles<light-duty natural gas vehicles<light-duty diesel vehicles<heavy-duty diesel vehicles. The results revealed that the source signatures of stable carbon isotope in vehicles used in current source apportionment could not well represent gasoline vehicles and natural gas vehicles. In future emission control and source apportionment, attention should be paid to the changes in emission factors and isotope signatures caused by the use of natural gas and the aging of motor vehicles.

Significant emission reductions of carbonaceous aerosols from residential coal burning by a novel stove

Carbonaceous aerosols (CA) are crucial components in the atmospheric PM2.5 and derived from diverse sources. One of the major sources for CA is from the incomplete combustion of bituminous coal that has been prevailingly used by household stoves in rural areas for heating during winter. To efficiently eliminate the CA emission, a new household stove (NHS) was developed based on a novel combustion technology and CA emissions from the NHS and a traditional household stove (THS) were comparably investigated under the actual stove operation conditions in a farmer's house. Compared with the THS, the emission factors of organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) from the NHS were reduced by 96%±1%, 98%±1%, and 91%±1% under the flaming process and 95%±1%, 96%±2%, and 83%±4% under the smoldering process, respectively. Additionally, the mass absorption efficiency of WSOC from the NHS reduced by 3 folds and the radiative forcing by WSOC relative to EC shrank remarkably by a factor of 3-8. Based on the reduction of emissions and light absorption of WSOC, the promotion of the NHS offers a possible solution to achieve the clean combustion of residential solid fuel.

Concentration, optical characteristics, and emission factors of brown carbon emitted by on-road vehicles

Atmospheric brown carbon (BrC) is a light-absorbing component that affects radiative forcing; however, this effect requires further clarification, particularly with respect to BrC emission sources, chromophores, and optical properties. In the present study, the concentrations, optical properties, and emission factors of organic carbon (OC), water-soluble OC (WSOC), and humic-like substances (HULIS) in fine particulate matter (PM2.5) emitted from vehicles in three road tunnels (the Wucun, Xianyue, and Wenxing tunnels in Xiamen, China) were investigated. The mass concentrations and light absorption of OC, WSOC, and HULIS were higher at the exits of each tunnel than at entrances, demonstrating that vehicle emissions were a BrC source. At each tunnel's exit, the average light absorption contributed by HULIS-BrC to water-soluble BrC (WS-BrC) and total BrC at 365 nm was higher than the corresponding carbon mass concentration contributed by HULIS (HULIS-C) to WSOC and OC, indicating that the chromophores of HULIS emitted from vehicles had a disproportionately high effect on the light absorption characteristics of BrC. The emission factors (EFs) of HULIS-C and WSOC mass concentrations were highest at the Xianyue tunnel; however, the EFs of HULIS-BrC and WS-BrC light absorption were highest at the Wenxing tunnel, indicating that the chromophore composition of BrC was different among the tunnels and that the mass concentration EFs did not correspond directly to the light absorption EFs.

Characterization and emission factors of carbonaceous aerosols originating from coke production in China.

Coking is a substantial source of carbonaceous aerosols in China, but the emission characteristics and pollution levels of coking-produced organic carbon (OC) and elemental carbon (EC) remain unknown, causing considerable uncertainty in emission estimates. In this study, the emission factors of OC (EFOC) and EC (EFEC) of typical coking plants in Shanxi, China, were measured. The measured EFEC and EFOC from fugitive emissions (7.43 and 9.54g/t) were significantly higher than those from flue gas (1.67 and 3.71g/t). The technological conditions of coke production affect the emissions of OC and EC. For example, the total emissions from coke plants that use 3.2-m-high coke ovens were greater than those from plants that use 4.3- and 6-m-high ovens. The EFOC and EFEC for plants conducting stamp charging were considerably higher than those for plants using top charging. The stable carbon isotopes of total carbon (δ13CTC), OC (δ13COC), and EC (δ13CEC) for fly ash during coking were-23.74‰ to-24.17‰,-23.32‰ to-23.87‰, and-23.84‰ to-24.14‰, respectively, and no clear isotopic fractionation was found during coke production. Different EC/OC ratios from different emission pathways and the carbon isotope signature of coke production should be considered when investigating the sources of carbonaceous aerosols. The total estimated EC and OC emissions from coke production in China were 3.93 and 5.72Gg in 2017, and Shanxi, Hebei, and Shaanxi made the largest contributions.

Size-segregated carbonaceous aerosols emission from typical vehicles and potential depositions in the human respiratory system

Particles emitted from five typical types of vehicles (including light-duty gasoline vehicles, LDG; heavy-duty gasoline vehicles, HDG; diesel buses, BUS; light-duty diesel vehicles, LDD and heavy-duty diesel vehicles, HDD) were collected with a dilution sampling system and an electrical low-pressure impactor (ELPI+, with particle sizes covering fourteen stages from 6 nm to 10 μm) on dynamometer benches. The mass concentrations and emission factors (EF) for organic carbon (OC) and elemental carbon (EC) were obtained with a DRI Model 2001 thermal/optical carbon analyzer. A respiratory deposition model was used to calculate the deposition fluxes of size-segregated carbonaceous aerosols in human respiratory system. Results indicated that the OC produced from LDG mainly existed in the size range of 2.5–10 μm, while EC from HDG enriched in 0.94–2.5 μm. For diesel vehicles, both OC and EC concentrations peaked at 0.094–0.25 μm. The OC/EC ratios for PM2.5 varied from different types of vehicles, from 0.61 to 8.35. The primary emissions from LDD and HDD exhibited high OC/EC ratios (>3), suggesting that using OC/EC higher than 2 to indicate the formation of secondary organic aerosol (SOA) was not universal. The emission factors for OC and EC of LDG (HDG) in PM10 were 1.78 (3.14) mg km−1 and 0.88 (4.32) mg km−1, respectively. The OC2 and OC3 were the main section (over 60%) of OC emitted from all the five types of vehicles. EC1 was the most abundant EC fraction of LDG (76.9%), while EC2 dominated for other types of vehicles (more than 62%). About 60% of the OC in ultrafine particles could be deposited in the alveoli. Diesel EC mainly could be deposited in the alveolar region. It is necessary to control the emission of ultrafine particles and diesel EC.

Effects of fuel types and fuel sulfur content on the characteristics of particulate emissions in marine low-speed diesel engine.

The emission of particulate matter from ships does great harm to human health and atmospheric environment. Sulfur emission regulations also affect particulate matter emissions due to fuel change. Particulate matter (PM) emitted from low-speed, two-stroke, large-power diesel engine were studied in test-bed experiments. Experiments were conducted at 25%, 50%, 75%, and 100% load with heavy fuel oil (HFO, 3.36%m/mS) and a lighter marine diesel oil (MDO, 0.1%m/mS). The experiments revealed that using MDO could decrease the mass emission factors (EFs) of PM compared to HFO due to the fuel quality and content; however, there was no obvious difference for the number EFs of PM. The main particle when using HFO consists sulfates and bound water, and the hydrate sulfur increased with the increased engine loads. Then, another 21% is organic carbon (OC). Emission factors for inorganic elements were also studied in particles from combustion of HFO and MDO. The EFs of OC and elemental carbon (EC) were affected by engine loads, fuel type, fuel sulfur content (FSC), and combustion conditions. The size distribution of OC was similar to EC, and there were two clearly peaks for every particulate matter sample. The key effect factor for EFs of PM with marine fossil fuels was FSC.

PAHs, elemental and organic carbons in a highway tunnel atmosphere and road dust: Discrimination of diesel and gasoline emissions

Total suspended solid (TSP) samples were collected in the Bolu Mountain Tunnel located on the highway in the axis of Edirne-Istanbul-Ankara in Turkey, by using PUF samplers. The concentrations of elemental and organic carbons (EC and OC) and particulate and gas phase priority pollutant (US-EPA) PAH compounds were determined at the entrance and the exit of the tunnel. Two sampling surveys were performed for summer and winter seasons in order to examine the seasonal changes of emissions. The OC peaks were associated with the sum concentrations of PAH compounds with respect to their boiling points. The fractions of OC1, EC3 and EC4 dominated in the tunnel particulate samples and OC4 and EC2 fractions formed the largest fraction of the particulate carbonaceous part of road dust. The results indicated that the predominant species in the particulate phase were the low-molecular weight (LMW) PAHs and low OC/EC ratios which indicated the dominance of the usage of diesel fuel in the vehicles. The highest emission factors (μg/vehicle−1 km−1) were observed for PhA, Ant and Py in summer, and for PhA, Fl and Py in winter seasons. Due to the strong influence of diesel-fueled vehicle emissions, higher correlations were observed between the fleet compositions of heavy duty vehicles (HDV) and obtained emission factors of OC, EC and PAHs than the correlations of light duty vehicles (LDV) in tunnel atmosphere for both summer and winter season. It was determined that PAHs potential risk for the health of the tunnel workers were significant.

In-Home Emissions Performance of Cookstoves in Asia and Africa

This paper presents results from eight field studies in Asia and Africa on the emissions performance of 16 stove/fuel combinations measured during normal cooking events in homes. Characterizing real-world emissions performance is important for understanding the climate and health implications of technologies being promoted as alternatives to displace baseline cooking stoves and fuels. Almost all of the stove interventions were measured to have substantial reductions in PM2.5 and CO emissions compared to their respective baseline technologies (reductions of 24–87% and 25–80%, for PM2.5 and CO emission rates, respectively), though comparison with performance guidance from the World Health Organization (WHO) and the International Organization for Standardization (ISO) suggests that further improvement for biomass stoves would help realize more health benefits. The emissions of LPG stoves were generally below the WHO interim PM2.5 emissions target (1.75 mg/min) though it was not clear how close they were to the most aspirational ISO (0.2 mg/min) or WHO (0.23 mg/min) targets as our limit of detection was 1.1 mg/min. Elemental and organic carbon emission factors and elemental-to-total carbon ratios (medians ranging from 0.11 to 0.42) were in line with previously reported field-based estimates for similar stove/fuel combinations. Two of the better performing forced draft stoves used with pellets—the Oorja (median ET/TC = 0.12) and Eco-Chula (median ET/TC = 0.42)—were at opposite ends of the range, indicating that important differences in combustion conditions can arise even between similar stove/fuel combinations. Field-based tests of stove performance also provide important feedback for laboratory test protocols. Comparison of these results to previously published water boiling test data from the laboratory reinforce the trend that stove performance is generally better during controlled laboratory conditions, with modified combustion efficiency (MCE) being consistently lower in the field for respective stove/fuel categories. New testing approaches, which operate stoves through a broader range of conditions, indicate potential for better MCE agreement than previous versions of water boiling tests. This improved agreement suggests that stove performance estimates from a new ISO laboratory testing protocol, including testing stoves across low, medium, and high firepower, may provide more representative estimates of real-world performance than previously used tests. More representative results from standardized laboratory testing should help push stove designs toward better real-world performance as well as provide a better indication of how the tested technologies will perform for the user.

Effects of biomass briquetting and carbonization on PM2.5 emission from residential burning in Guanzhong Plain, China

In this study, maize straw, wheat straw, and wood branches and their processed products (i.e., briquettes and charcoals) were used to investigate the emission factors (EFs) of PM2.5 components and the influence of form changing. The EFs of organic carbon (OC) was 241 ± 39.7 to 3920 ± 792 mg kg−1; OC was the largest contributor in PM2.5. The EFs of PM2.5, OC and elemental carbon (EC) demonstrated that charcoal was the most efficient in reducing PM2.5 and carbonaceous fraction emissions, followed by briquettes compared with raw fuels in residential burning use. Among cations, K+ had the highest EF, whereas Cl− has the highest EF among anions; the presence of both K+ and Cl− was attributable to high abundance in biomass. Cl, K, S, and Na (in descending order) contributed more than 95% of total elements with high EFs; the other elements, particularly heavy metals, had very low EFs. The EFs of total polycyclic aromatic hydrocarbons (PAHs) and saccharides were in the following order of magnitude: raw fuels > briquettes > charcoals. PAHs with four rings (i.e., pyrenes) dominated the total PAHs in PM2.5−, whereas among saccharides, levoglucosan had the largest EFs (0.03–110.41 mg kg−1). Briquettes, with simple process and reasonable cost, demonstrated a good ability in decreasing PM2.5 emission with potential of 53% (765,000–427,000 t year−1), and their emission reduction potential were much higher for straws than for branches. Charcoals demonstrated considerable emission reduction potential for straw (93.7% averagely for PM2.5 and compositions) and comparable for wood branches (80% averagely) while its complex process and high cost should be considered. More than 600,000 t of PM2.5 and thousands of tons of PAHs and saccharides are estimated to be eliminated annually if all raw biomass fuels are processed through carbonization. Considering the efficiency–cost ratios, biomass briquetting may aid clean heating in rural areas, in addition to the “natural gas and electricity replacement strategy,” in China and other countries facing similar problems.

Quantification of Carbonaceous Aerosol Emissions from Cookstoves in Senegal

ABSTRACT In some regions of the world, cooking with solid biomass fuels in open fires constitutes the largest source of elemental and organic carbon emissions. However, cooking-related carbonaceous aerosols are still poorly characterized. This paper presents an innovative characterization of elemental and organic carbon (EC and OC) emissions from cookstoves in West Africa. Four stove types (three-stone fire, rocket stove, basic ceramic stove, and gasifier) using two wood species (dimb and filao) were analyzed on a laboratory scale. The EC and OC emission factors based on fuel energy (EFs) when burning dimb were higher for all stoves, highlighting the need to account for the fuel type when reporting cookstove EFs. The highest EC EF was found for the rocket stove (0.18 ± 0.06 g MJ–1 and 0.06 ± 0.01 g MJ–1 for dimb and filao, respectively). The other tested stoves exhibited the same EC EF when burning dimb (0.09 ± 0.02 g MJ–1) and EC EFs ranging between 0.04 ± 0.01 and 0.05 ± 0.01 g MJ–1 when burning filao. The OC EF was highest, on average, for the gasifier (0.08 ± 0.01 g MJ–1), followed by those for the three-stone fire (0.18 ± 0.03 g MJ–1) and the basic ceramic stove (0.21 ± 0.08 g MJ–1). However, the results from testing the rocket stove and the three-stone fire under real cooking conditions using dimb wood indicate that the laboratory-scale tests overestimate the actual EC EFs. Also, the rocket stove did not show a reduction in wood use compared to the three-stone fire, suggesting that the carbonaceous aerosol emissions from the former produce more warming than those from the latter. Therefore, the total EC and OC stove emissions, in addition to the EFs, must be reported. As the impacts of carbonaceous aerosol highly depend on the location of emission, this study contributes valuable data to emission inventories and climate prediction models at national and regional levels.

Sugarcane burning emissions: Characterization and emission factors

Open burning of sugarcane (Saccharum officinarum) has a large impact in regional atmospheric pollution and global climatic change. In this research, pollutant emissions from sugarcane residues burning were measured in order to determine the emission factors (EFs) of elemental carbon (EC), organic carbon (OC), 18 polycyclic aromatic hydrocarbons (PAHs), K, Na, Ca, Mg, NO3−, SO42−, NH4+, and Cl− contained in particulate matter (PM), as well as EFs of the gaseous pollutants, carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and 37 volatile organic compounds (VOCs). Experiments were carried out in an open combustion chamber equipped with isokinetic sampling, following EPA 5 and modified EPA 201-A methods. Preliminary tests showed that continuous feeding of residues does not represent the open burning carried out in the field since flaming stage is sustained, thus batch feeding of residues was used to perform around 30 experiments. Gaseous pollutants EFs were 1618 ± 108, 25.7 ± 2.04 and 2.29 ± 0.13 g kg−1 for CO2, CO and CH4 respectively, while C2 compounds have the highest EF of VOCs. PM10 and PM2.5 accounted for 55% and 36% of total PM mass, whereas carbonaceous species (EC and OC) accounted for 66% in PM2.5 and 58% in PM10 and total PM mass. Emission factors of EC varied from 0.34 to 0.37 g kg−1, and EF of OC were 0.44, 0.67 and 1.2 g kg−1 for PM2.5, PM10 and total PM, respectively. Highest EFs of determined elements and anions were K and Cl−, respectively. Heavy PAHs such as benzo[b]fluoranthene, bezo[k]fluranthene and benzo[a]pyrene presented the greatest EFs with 0.265 ± 0.04, 0.264 ± 0.08 and 0.254 ± 0.015 mg kg−1 respectively. Kruskal Wallis tests indicated that EFs had no significant differences among sugarcane varieties harvested in sites with different altitudes and climate, thus they can be applied for inventories estimations in world regions similar to Mexico, as well as in air quality forecasting models and climatic model allowing a better knowledge of air pollution and climatic change scenarios. The results of this research can be the base to design and establish public policies in order to regulate and eventually eliminate the practices of pre-harvest and post-harvest sugarcane burning.

Size-resolved Emission Factors of Carbonaceous Particles from Domestic Coal Combustion in China

China is one of the most important contributors to the global burden of carbonaceous aerosols, of which domestic coal combustion occupies a large fraction. Uncertainty in the emission factors (EFs) directly influences the accuracy of corresponding emission inventories. In the present study, based on domestic burning tests with a dilution sampling system, nine size-segregated particle classes emitted from the burning of three kinds of honeycomb coals (under flaming and smoldering burning conditions) and four kinds of chunk coals, including bituminous and lignite, were collected via a cascade impactor (FA-3). Organic and elemental carbon (OC and EC, respectively) were analyzed using the thermal-optical method. The EFs of particulate matter (PM), OC, and EC for nine size ranges were obtained. For honeycomb coals, the EFs of OC and EC in PM2.1 were 0.07 g·kg-1 and 0.002 g·kg-1, respectively, under flaming burning conditions and 0.10 g·kg-1 and 0.001 g·kg-1, respectively, under smoldering burning conditions. Carbonaceous particles exhibited higher EFs under flaming burning conditions. For chunk coals, the EFs of OC and EC in PM2.1 were 1.4 g·kg-1 and 0.02 g·kg-1, respectively, which are about one magnitude higher than those for honeycomb coal burning. Particulate matter and its associated carbonaceous components preferred to concentrate in fine particles. The EFs of carbonaceous components peaked at the size of ≤ 0.43 μm and 0.43-0.65 μm for honeycomb coal burning and chunk coal burning, respectively.

Emission factors of organic carbon and elemental carbon for residential coal and biomass fuels in China- A new database for 39 fuel-stove combinations

In recent years many households in northern China's rural areas tend to furnish their houses with water-circulating piping system for heating, which entails mini-boiler stoves to heat water via raw coal chunk or biomass pellets. In this study, consistent efforts were made to obtain first-hand emission factors of organic carbon (EFOC) and elemental carbon (EFEC) for residential solid fuel combustion. A total of 39 fuel/stove combinations, covering seven coals (with different geological maturities), eleven biomass fuels, and five different stoves, were tested. The mean EFOC and EFEC were (4.29 ± 2.33) and (4.43 ± 2.18) g/kg for residential coal combustion, (2.16 ± 4.47) and (0.42 ± 1.01) g/kg for indoor biomass burning. The EFs for tested coal combustion display a “bell shape” with the maximum EF value occurring at bitumite of middle maturity. Coal briquetting in this study led to a significant decrease in EFEC but a notable increase in EFOC, which contradicted with the result from some of previous studies that coal briquetting always leads to relatively low emissions of both OC and EC. The inside reason deserves further clarification. Averaging over the two mini-boiler stoves shows that the introduction of mini-boiler stoves can reduce 5% and 10% of OC from anthracite and bitumite, respectively, and 47% and 53% of EC from anthracite and bitumite, respectively, suggesting that transfer from pure heating stoves to mini-boiler stoves seems unlikely to increase carbonaceous particle emissions, particularly EC. The more significant decline in EFEC than in EFOC indicates that the access to mini-boiler stove for winter heating is very likely to be both a clean air measure and a warming mitigation approach. Updated emission inventories in China for the year of 2014 showed that the OC and EC emissions were 338 Gg and 529 Gg, respectively, from residential coal combustion, and 557 Gg and 79 Gg, respectively, from household biomass burning.

Measurements of OC and EC Emission Factors for Light-duty Gasoline Vehicles

Organic carbon (OC) and elemental carbon (EC) emission factors from 27 State 3-5 light-duty gasoline vehicles (LDGVs) were tested in this study using a CVS (Constant Volume Sampling) system on a dynamometer. The influences of start conditions, driving cycles, and fuel injection technologies on the OC and EC emissions were analyzed. The results show that the OC emission factors of the tested State 3 to 5 LDGVs were (2.09±1.03), (1.59±0.78), and (0.75±0.31) mg·km-1, respectively, and the EC emission factors were (1.98±1.42), (1.57±1.80), and (0.65±0.49) mg·km-1. Both OC and EC emissions significantly decreased with the promotion of emission standards. The OC/EC ratios were 1.54±0.92, 1.53±0.91, and 1.47±0.66, respectively. OC1, OC2, EC1, and EC2 were the most important carbonaceous components from LDGVs, accounting for 15%, 20.6%, 22.2%, and 21.7%, respectively. OC and EC emission factors under cold-start conditions were 1.4 and 1.8 times those under hot-start conditions. OC and EC emission factors for highway cycles were 2 and 4 times those for urban cycles. OC emission factors from GDI (Gasoline Direct Injection) engines were close to those from PFI (Port Fuel Injection) engines. However, their EC emission factors were 1.7 times those from PFI engines. With the increasing popularity of GDI engines in LDGV fleets in China, the EC emissions from these engines should be paid more attention in the future.

Determination of real-world emission factors of trace metals, EC, OC, BTEX, and semivolatile organic compounds (PAHs, PCBs and PCNs) in a rural tunnel in Bilecik, Turkey

A field study was performed in a rural tunnel to determine pollutant concentrations, sources and on road vehicle emission factors (EFs) of particulate matter, trace metals, elemental carbon (EC), organic carbon (OC), benzene, toluene, ethyl benzene and xylenes (BTEX), and polycyclic aromatic hydrocarbons (PAHs). Emission factors (EFs) for polychlorinated naphthalenes (PCNs) and polychlorinated biphenyls (PCBs) were also determined. A 12-day extensive sampling campaign during morning and afternoon periods at inlet and exit stations of the tunnel was conducted. Morphology of the particles was also investigated by Scanning Electron Microcopy (SEM). Correlation analysis, factor analysis and diagnostic PAH ratios were utilized to identify emission sources of trace metals. Identified sources include brake wear (33%), resuspension of road dust (15%), tyre wear (12%), exhaust emissions (10%), and lubricants (9%). Based on the PAH diagnostic ratios, major sources of PAHs were estimated as diesel emissions.EFs were comparable with the literature and varied from 31.5 to 295.4 mg vehicle−1 km−1 with an average of 129.2 ± 80 mg vehicle−1 km−1 for PM2.5. PM2.5–10 EFs varied between 15.9 and 236.1 mg vehicle−1 km−1 with an average of 96 ± 30 mg vehicle−1 km−1. Average EC EFs were 40.3 ± 9.8 mg vehicle−1 km−1 for PM2.5 samples and 19.5 ± 0.5 mg vehicle−1 km−1 for PM2.5–10 samples while OC EFs were 33.7 ± 18 and 15.5 ± 8.4 mg vehicle−1 km−1 for fine and coarse particles, respectively. EFs of elements were generally 2 (Al) to 59 (Mg) times higher than those previously reported in the literature. Compared to literature, relatively higher EFs for Σ13PAHs (range: 48.1–168 μg vehicle−1 km−1, average: 84.3 ± 46.4 μg vehicle−1 km−1) were obtained. BTEX emission factors were in the range of 4.2 ± 4.7 mg vehicle−1 km−1 (m + p-xylene) and 16.7 ± 10.5 mg vehicle−1 km−1 (toluene). Average EFs for ΣPCBs and ΣPCNs were 12.06 ± 5.3 μg vehicle−1 km−1 and 88.9 ± 70.4 ng vehicle−1 km−1, respectively.

Impact of primary and secondary air supply intensity in stove on emissions of size-segregated particulate matter and carbonaceous aerosols from apple tree wood burning

In order to assess emission factors (EF) more accurately from household biomass burning, a series of laboratory-controlled apple tree wood burning tests were conducted to measure the EFs of size-segregated particulate matter (PM) and carbonaceous aerosols. The controlled burning experiments were conducted with designed primary air (PA) and secondary air (SA) supply intensity. An optimum value of 7m3·h−1 was found for SA, resulting the highest modified combustion efficiency (92.4±2.5%) as well as the lowest EFs of PM2.5 (0.13±0.01g·MJ−1), OC (0.04±0.03g·MJ−1) and EC (0.03±0.01g·MJ−1). SA values of 7 and 10m3·h−1 resulted the lowest EFs for all the different PM sizes. In a test with PA of 6m3·h−1 and SA of 7m3·h−1, very low EFs were observed for OC1 (8.2%), OC2 (11.2%) and especially OP (Pyrolyzed OC) (0%, not detected), indicating nearly complete combustion under this air supply condition. Besides SA, higher PA was proved to have positive effects on PM and carbonaceous fraction emission reduction. For example, with a fixed SA of 1.5m3·h−1, EFs of PM2.5 decreased from 0.64 to 0.27g·MJ−1 when PA increased from 6 to 15m3·h−1 (P<0.05). Similar reductions were also observed in EFs of OC, EC and size segregated PM.

Emission of organic carbon, elemental carbon and water-soluble ions from crop straw burning under flaming and smoldering conditions

Emissions from major agricultural residues were measured using a self-designed combustion system. Emission factors (EFs) of organic carbon (OC), elemental carbon (EC), and water-soluble ions (WSIs) (K+, NH4+, Na+, Mg2+, Ca2+, Cl−, NO3−, SO42–) in smoke from wheat and rice straw were measured under flaming and smoldering conditions. The OC1/TC (total carbon) was highest (45.8% flaming, 57.7% smoldering) among carbon fractions. The mean EFs for OC (EFOC) and EC (EFEC) were 9.2±3.9 and 2.2±0.7g/kg for wheat straw and 6.4±1.9 and 1.1±0.3g/kg for rice straw under flaming conditions, while they were 40.8±5.6 and 5.8±1.0g/kg and 37.6±6.3 and 5.0±1.4g/kg under smoldering conditions, respectively. Higher EC ratios were observed in particulate matter (PM) mass under flaming conditions. The OC and EC for the two combustion patterns were significantly correlated (p<0.01, R=0.95 for wheat straw; p<0.01, R=0.97 for rice straw), and a higher positive correlation between OC3 and EC was observed under both combustion conditions. WSIs emitted from flaming smoke were dominated by Cl− and K+, which contributed 3.4% and 2.4% of the PM mass for rice straw and 2.2% and 1.0% for wheat straw, respectively. The EFs of Cl− and K+ were 0.73±0.16 and 0.51±0.14g/kg for wheat straw and 0.25±0.15 and 0.12±0.05g/kg for rice straw under flaming conditions, while they were 0.42±0.28 and 0.12±0.06g/kg and 0.30±0.27 and 0.05±0.03g/kg under smoldering conditions, respectively. Na+, Mg2+, and NH4+ were vital components in PM, comprising from 0.8% (smoldering) to 3.1% (flaming) of the mass. Strong correlations of Cl− with K+, NH4+, and Na+ ions were observed in rice straw and the calculated diagnostic ratios of OC/EC, K+/Na+ and Cl−/Na+ could be useful to distinguishing crop straw burning from other sources of atmospheric pollution.

Emissions from several in-use ships tested by portable emission measurement system

Seven ships were tested using portable emission measurement system. Particles from three ships were sampled using quartz-filters and analyzed using Thermal/Optical Carbon Analyzer and GC–MS. The emission factors of CO, HC, NOx and PM are 11.00–84.60g/kg, 22.75–98.88g/kg, 0.72–5.83g/kg and 0.15–9.53g/kg, respectively. In most cases, the ships emit larger quantity of pollutants during cruising. For particle number, the majority is formed in the nucleation mode. The nucleation mode and the accumulation mode from ships during maneuvering increase by 2.63 and 3.52 times respectively, compared with those from ships during cruising. Particle mass is dominated by the accumulation mode and the coarse mode. Analysis of the samples shows that OC is the major composition of carbonaceous particle, whose mass fraction is 0.52–0.88. The emission factors of OC and EC are 0.29–1.44g/kg and 0.04–0.64g/kg, respectively. Most of the particle-phase PAHs are medium molecular weight PAHs, while high molecular weight PAHs are seldom observed.

Emission estimates of organic and elemental carbon from household biomass fuel used over the Indo-Gangetic Plain (IGP), India

Biomass burning emits large amount of aerosols and trace gases into the atmosphere, which have significant impact on atmospheric chemistry and climate. In the present study, we have selected seven Indian states (Delhi, Punjab, Haryana, Uttar Pradesh, Uttarakhand, Bihar and West Bengal) over the IGP, India. Samples of biomass fuel (Fuel Wood, Crop Residue and Dung Cake) from rural household have been collected (Saud et al., 2011a). The burning process has been simulated using a dilution sampler following the methodology developed by Venkatraman et al. (2005). In the present study, emission factor represents the total period of burning including pyrolysis, flaming and smoldering. We have determined the emission factors of organic carbon (OC) and elemental carbon (EC) from different types of biomass fuels collected over the study area. Average emission factors of OC from dung cake, fuel wood and crop residue over IGP, India are estimated as 3.87 ± 1.09 g kg−1, 0.95 ± 0.27 g kg−1, 1.46 ± 0.73 g kg−1, respectively. Similarly, average emission factors of EC from dung cake, fuel wood and crop residue over IGP, India are found to be 0.49 ± 0.25 g kg−1, 0.35 ± 0.07 g kg−1 and 0.37 ± 0.14 g kg−1, respectively. Dung cake and crop residue are normally not used in Uttarakhand. Annual budget of OC and EC from biomass fuels used as energy in rural households of IGP, India is estimated as 361.96 ± 170.18 Gg and 56.44 ± 29.06 Gg respectively. This study shows the regional emission inventory from Indian scenario with spatial variability.