Submicron PM Research Articles

Formation and migration of trace elements in condensable particulate matter with the finest particle size distribution

There is a lack of existing studies on the effect of particle size distribution on the condensation behavior of trace elements (TEs) in condensable particulate matter (CPM) surfaces. The effects of TEs on the formation of PM10 and CPM10 with different particle sizes in coal-fired flue gas were studied using an entrained flow reactor. Hg and Se were enriched in ultra-fine CPM. As, Pb, and Cr were enriched in sub-micron and ultra-micron PM. For Hg2+, As3+ and Cr6+, a higher toxicity state was observed in PM10. For Se4+, a higher toxicity state was observed in CPM10. TEs in the form of volatile elements and oxides tend to be enriched in ultra-fine particle sizes, while TEs in the form of metal salts tend to be enriched in sub-micron and ultra-micron particle sizes. The formation mechanism of TEs on PM and CPM surfaces was closely related to the volatility and speciation of TEs and the particle sizes of PM and CPM. The results established the qualitative (speciation of TEs) and quantitative (concentration of TEs) correlation between TEs and the finest particle sizes. This study will help to better control the emission of TEs and CPM during coal combustion.

Impact of Biomass Burning on Air Quality in Temuco City, Chile

ABSTRACT Residential wood burning emits a complex mixture of particulate and gaseous compounds. In this article we show an in-depth chemical characterization of particulate matter evidencing the impact of biomass burning on the urban air quality in Greater Temuco, the capital city of the Araucania Region, Chile. The measurements were carried out at two sites, Las Encinas and Padre Las Casas, in spring and winter. Extremely high fine particulate matter (PM2.5) concentrations (up to 700 µg m–3) were frequently observed at both stations in the wintertime, while in spring, PM2.5 concentrations were significantly lower (campaign-average 6.4 and 8.6 µg m–3 in Las Encinas and Padre Las Casas, respectively). Chemical composition of submicron PM was dominated by organics (average 87%) followed by inorganic ions (10–30%) and a minor contribution of black carbon (< 5%). In the wintertime, atmospheric levels of biomass burning tracers, such as levoglucosan, potassium and chloride, were elevated and their diurnal profiles showed a significant concentration increase in the evening. Diurnal profiles combined with the in-depth chemical analysis clearly indicated that in the wintertime local biomass burning was the main source of air pollutants in the region. Furthermore, in winter, most of the high concentration events correlated with the periods with high surface pressure, low temperature and low wind speed. These events matched with higher temperatures at high altitude than at the surface characterizing the typical profile of a vertical inversion that prevents the dilution of air pollutants.

Mitigation of Secondary Organic Aerosol Formation from Log Wood Burning Emissions by Catalytic Removal of Aromatic Hydrocarbons.

Log wood burning is a significant source of volatile organic compounds including aromatic hydrocarbons (ArHC). ArHC are harmful, are reactive in the ambient atmosphere, and are important secondary organic aerosol (SOA) precursors. Consequently, SOA represents a major fraction of the sub-micron organic aerosol pollution from log wood burning. ArHC reduction is thus critical in the mitigation of adverse health and environmental effects of log wood burning. In this study, two Pt-based catalytic converters were prepared and tested for the mitigation of real-world log wood burning emissions, including ArHC and SOA formation, as well as toxic carbon monoxide and methane, a greenhouse gas. Substantial removal of mono- and polycyclic ArHC and phenolic compounds was achieved with both catalysts operated at realistic chimney temperatures (50% conversion was achieved at 200 and 300 °C for non-methane hydrocarbons in our experiments for Pt/Al2O3 and Pt/CeO2-Al2O3, respectively). The catalytically cleaned emissions exhibited a substantially reduced SOA formation already at temperatures as low as 185-310 °C. This reduces the sub-micron PM burden of log wood burning significantly. Thus, catalytic converters can effectively reduce primary and secondary log wood burning pollutants and, thereby, their adverse health impacts and environmental effects.

Analysis of organophosphorus flame retardants in submicron atmospheric particulate matter (PM1)

This study is aimed to determine the occurrence of organophosphorus flame retardants (OPFRs) in atmospheric particulate matter with an aerodynamic diameter of less than 1 µm (PM 1 ). The analytical method is based on Soxhlet extraction and a clean-up step with Florisil solid phase extraction (SPE). Detection and quantification was performed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Validation included laboratory and field blank tests as well as the determination of the method efficiency using spiked quartz filters with 20 ng and 200 ng of OPFR mixture. Ambient air PM samples with particle concentrations between 4 and 26 µg/m 3 were collected at an urban background site in Barcelona under contrasting meteorological conditions in order to study occurrence of OPFRs in relation to particle loads. In these samples, OPFRs were detected at levels ranging from a few pg/m 3 to 1200 pg/m 3 and substantial correlations were observed between the levels of certain OPFRs and atmospheric particle loadings. The presence of individual compounds in pg/m 3 concentrations levels in the sub-micron PM mode (PM 1 ) at an urban background site indicates a considerable exposure to these compounds for the human population in this area. This is the first study to determine OPFR in PM 1 .

The influence of NaCl and Na2CO3 on fine particulate emission and size distribution during coal combustion

This research focuses on the effects of NaCl and Na2CO3 sodium additives on fine particulate emission and size distribution. The experiment was conducted in a drop tube furnace under typical power plant conditions. Particulate emissions were measured by an electrical low pressure impactor (ELPI+). NOX emissions were studied using a Testo350 flue gas analyzer. Both NaCl and Na2CO3 sodium additives have been shown to reduce NOX emissions during coal combustion. Sodium additives also increased the amount of ultrafine particulate matter (PM0.1), especially, PM with an aerodynamic diameter (Da) in the 0.0212μm–0.0561μm range increased significantly. NaCl and Na2CO3 will affect the emission of fine PM (PM10) through different mechanisms. NaCl was prone to vaporization when it was added to furnace. Gas-phase Na will generate Na2SO4/Na2SiO3 vapor followed by nucleation/condensation. Increasing the Na/N ratio increased the number of particles and the mass-concentration of submicron PM (PM1), but had little effect on the concentration of PM1∼10. Alternatively, Na2CO3 mostly produced PM greater than 10μm in Da via a breakage/melt-agglomeration process. A small portion of the Na2CO3 reacted to generate NaCl and influence the submicron PM. As the Na/N ratio increased, the amount of PM less than 0.1μm in Da (PM0.1) and PM between 1μm and 10μm in Da (PM1∼10) decreased.

A case study into the measurement of ship emissions from plume intercepts of the NOAA ship &amp;lt;i&amp;gt;Miller Freeman&amp;lt;/i&amp;gt;

Abstract. Emissions factors (EFs) for gas and sub-micron particle-phase species were measured in intercepted plumes as a function of vessel speed from an underway research vessel, the NOAA ship Miller Freeman, operating a medium-speed diesel engine on low-sulfur marine gas oil (fuel sulfur content ~0.1% by weight). The low-sulfur fuel in use conforms to the MARPOL fuel sulfur limit within emission control areas set to take effect in 2015 and to California-specific limits set to take effect in 2014. For many of the particle-phase species, EFs were determined using multiple measurement methodologies, allowing for an assessment of how well EFs from different techniques agree. The total sub-micron PM (PM1) was dominated by particulate black carbon (BC) and particulate organic matter (POM), with an average POM / BC ratio of 1.3. Consideration of the POM / BC ratios observed here with literature studies suggests that laboratory and in-stack measurement methods may overestimate primary POM EFs relative to those observed in emitted plumes. Comparison of four different methods for black carbon measurement indicates that careful attention must be paid to instrument limitations and biases when assessing EFBC. Particulate sulfate (SO42−) EFs were extremely small and the particles emitted by Miller Freeman were inefficient as cloud condensation nuclei (CCN), even at high super saturations, consistent with the use of very low-sulfur fuel and the overall small emitted particle sizes. All measurement methodologies consistently demonstrate that the measured EFs (fuel mass basis) for PM1 mass, BC and POM decreased as the ship slowed. Particle number EFs were approximately constant across the speed change, with a shift towards smaller particles being emitted at slower speeds. Emissions factors for gas-phase CO and formaldehyde (HCHO) both increased as the vessel slowed, while EFs for NOx decreased and SO2 EFs were approximately constant.

Inflammatory effects on human lung epithelial cells after exposure to diesel exhaust micron sub particles (PM 1.0) and pollen allergens

Asthma is currently defined as a chronic inflammatory disease of the airway. Several evidence indicate that vehicle emissions in cities is correlated with the allergic respiratory diseases. In the present study, we evaluated in the A549 cells the production and release of IL-4, IL-5 and IL-13 after treatment with sub-micron PM 1.0 particles (PM 1.0), Parietaria officinalis (ALL), and PM 1.0 + ALL together. Our data demonstrated that PM 1.0 + ALL together exhibited the greatest capacity to induce A549 cells to enhance the expression of IL-4 and IL-5 compared with the only PM 1.0 or ALL treatment. Interestingly, IL-13 that is necessary for allergen-induced airway hyper responsiveness, is increased in cells treated with PM 1.0 + ALL together, but is higher expressed when the cells are treated only with the allergen. Our data support the hypothesis that the urban environment damage the acinar lung units and activates cells of the immune system.

Influence of woody biomass (cedar chip) addition on the emissions of PM 10 from pulverised coal combustion

Co-combustion of pulverised coal with a woody biomass, cedar chip was conducted in a lab-scale drop-tube furnace (DTF) to investigate the synergetic interaction between the inorganic elements of different fuels and the emissions of sub-micron particles (particles smaller than 1.0 μm in size, PM 1) and super-micron particles (particles in the size range of 1.0–10 μm, PM 1+) during co-firing. The mass fraction of cedar chip in fuel blend ranged from 10% to 50%. All the fuels were burnt in air at two furnace temperatures, 1200 and 1450 °C. The results indicate that, under an identical calorific input, combustion of cedar chip alone favored the emission of sub-micron PM 1, which is dominated by volatile elements including K, Ca, Fe, Na and P. A large fraction of K and Na were most probably present as gaseous vapors in the furnace. The other metals mainly condensed into nano-scale nuclei which subsequently coagulated into a variety of sizes in flue gas. Coal combustion alone favored the release of super-micron particles rich in Al and Si. Emission of PM upon co-firing was a function of both cedar chip share and furnace temperature. At a small mass fraction for cedar chip in fuel blend, e.g. 10% tested here, interaction between the inorganic elements of single fuels was insignificant at either furnace temperature. Accordingly, the quantities of PM 1 and PM 1+ emitted from co-firing at 10% cedar chip were slightly higher than from the combustion of coal alone, due to the contribution of cedar chip. Significant interaction between the inorganic elements of single fuels was observed for co-firing of coal with >10% cedar chip at the furnace temperature of 1450 °C. As has been confirmed, adding 20–30% cedar chip to coal resulted in the shift of approximately 90% of PM 1 and 50% PM 1+ into coarse ash particles. For the cedar chip-derived alkali vapors and nano-scale/sub-micron particles, the rates of their shift into larger particles were influenced by two competing routes, homogeneous coagulation and surface reaction with coal-derived kaolin. In contrast, the shift of super-micron particles was primarily determined by their collision probability with the coal-derived mineral grains in bulk gas. A sticky surface for particles is also essential. The shift of individual metals into coarse ash differed distinctly from one another.

Positive matrix factorization and trajectory modelling for source identification: A new look at Indian Ocean Experiment ship observations

The sources of aerosols on a regional scale over India have only recently received attention in studies using back trajectory analysis and chemical transport modelling. Receptor modelling approaches such as positive matrix factorization (PMF) and the potential source contribution function (PSCF) are effective tools in source identification of urban and regional-scale pollution. In this work, PMF and PSCF analysis is applied to identify categories and locations of sources that influenced surface concentrations of aerosols in the Indian Ocean Experiment (INDOEX) domain measured on-board the research vessel Ron Brown [Quinn, P.K., Coffman, D.J., Bates, T.S., Miller, T.L., Johnson, J.E., Welton, E.J., et al., 2002. Aerosol optical properties during INDOEX 1999: means, variability, and controlling factors. Journal of Geophysical Research 107, 8020, doi:10.1029/2000JD000037]. Emissions inventory information is used to identify sources co-located with probable source regions from PSCF. PMF analysis identified six factors influencing PM concentrations during the INDOEX cruise of the Ron Brown including a biomass combustion factor (35–40%), three industrial emissions factors (35–40%), primarily secondary sulphate–nitrate, balance trace elements and Zn, and two dust factors (20–30%) of Si- and Ca-dust. The identified factors effectively predict the measured submicron PM concentrations (slope of regression line=0.90±0.20; R 2=0.76). Probable source regions shifted based on changes in surface and elevated flows during different times in the ship cruise. They were in India in the early part of the cruise, but in west Asia, south-east Asia and Africa, during later parts of the cruise. Co-located sources include coal-fired electric utilities, cement, metals and petroleum production in India and west Asia, biofuel combustion for energy and crop residue burning in India, woodland/forest burning in north sub-Saharan Africa and forest burning in south-east Asia. Significant findings are equivalent contributions of biomass combustion and industrial emissions to the measured aerosol surface concentrations, the origin of carbonaceous aerosols largely from biomass combustion and the identification of probable source regions in Africa, west Asia, the Arabian peninsula and south-east Asia, in addition to India, which affected particulate matter concentrations over parts of the INDOEX domain covered by the Ron Brown cruise.

Emission characteristics and chemical composition of PM&lt;SUB&gt;10&lt;/SUB&gt; from two coal fired power plants in China

AbstractBy using low pressure impactor, fly ash was sampled in the entrance and exit of the dust cleaning equipments, such as ESP and venturi scrubber, in a 50 and 100 MW utility boiler. The composition, mass size distribution and microstructure of fly ash were measured. A similar bimodal distribution of PM10 was obtained in the studied boilers. The small and large modes are formed at 0˙1 and 4˙0 μm respectively. Based on the comparison of concentrations of Si and Al in the size segregated ash, it is concluded that the ash with size smaller than 0˙377 μm is formed by the nucleation of vaporised mineral components and growth via coagulation and heterogeneous condensation. The results by microstructure measurements showed that the typical microstructure of submicron and coarse PM is spherical, except for a few irregular particles in shape. The collection efficiency of the dust cleaning equipments had a minimum in particle size range of 0˙01–1 μm.

The Development of PM Emission Factor for Small Incinerators and Boilers

This study is intended to develop the emission factors of particulate matter such as TPM (total particulate matter), PM-10 (particulate matter less than 10 micrometers in aerodynamic diameter), PM-2.5 (particulate matter less than 2.5 micrometers in aerodynamic diameters) and several types of inorganic matter from small-size incinerators (less than 250 kg hr−1 capacity) and boilers (less than 5 ton hr−1 capacity as steam generation) for various compositions of wastes and fuels, respectively. The emission factors for particulate matter from boilers were similar to the US EPA data. However, the emission factors from small incinerators were higher than the emission factors developed in other countries because the emission characteristics were different, especially with respect to the combustor's capacity. Emission factors for heavy metals such as cadmium, manganese, chromium, magnesium, lead, zinc, and copper were also investigated. The emission factors in this study were higher than those in other studies. Particle size distribution of PM-10 and the ratio of submicron PM to TPM were observed and a mode (peak) of submicron size particles together with a higher concentration of them was found, which could be explained by the formation of fines from vaporized metals in wastes.