Dilution Sampling System Research Articles

Characteristics of intermediate volatility organic compounds emitted from inland vessels with different influential factors and implication of reduction emissions

Ships could emit an abundance intermediate volatility organic compounds (IVOCs). In recent years, many studies on the emission characteristics of IVOCs have focused on the burning of heavy fuel oil by ocean-going ships; however, few have focused on inland vessels which have a more significant impact on air quality and human health owing to their closer proximity to cities than ocean-going ships. In this study, the IVOC emission factors (EFIVOCs) of three inland vessels were determined using a dilution sampling system considering different influencing factors (ship age and operating conditions). The results showed that the EFIVOCs values ranged from 869.9 to 7607 mg/kg fuel, with an average of 4128 ± 2703 mg/kg fuel. In addition, the age of the vessel was found to have a dramatic effect on emissions with the average EFIVOCs of inland vessels aged >10 years was 4300 ± 4319, 5769, and 6484 ± 1586 mg/kg fuel under cruising, idling, and maneuvering conditions, respectively, while that of vessels <10 years old was 1180 ± 328.3 mg/kg fuel when maneuvering. The percentages of emission factors for unresolved complex mixture (UCM), normal alkanes (n-alkanes), branched alkanes (b-alkanes), and polycyclic aromatic hydrocarbons (PAHs) from inland vessels were 82.1 ± 2.6 %, 5.2 ± 0.9 %, 10.6 ± 2.0 % and 2.0 ± 0.6 % of the total IVOCs, respectively. The secondary organic aerosols (SOA) production of inland vessels was estimated to be 1212 ± 801.7 mg/kg fuel, which was substantially higher than those of diesel vehicles, non-road construction machinery, and gasoline vehicles reported by other researches. Moreover, based on the ship movement and measured EFIVOCs data, the IVOCs emission inventory of inland vessels in Jiangsu Province and China in 2016 was 4.2 ± 2.8 and 32.0 ± 21.0 Gg respectively, which was comparable to those from diesel vehicle emissions.

Black carbon emissions from modern automated cordwood stoves for space heating

AbstractWood burning stove design is improving as regulation become stricter for particulate matter emissions. This study describes results of black carbon (BC) emissions from three modern automated wood stoves when tested in common failure modes using a test protocol that included cold‐starts, high and low fuel loading densities, and use of overly large pieces of fuel. Emission sampling was performed using a dilution sampling system in tandem with an aethalometer to measure BC with high time resolution. Results show that the time‐weighted average BC emission rates were 0.91, 4.30, and 1.74 g/h for the three stoves tested (A, B, and C respectively), the values, both higher and lower than the United States 2020 certification test emission limit of 2.5 g/h. The results demonstrate good performance overall, given the rigorous nature of the testing protocol used. The aethalometer data showed that the performance was relatively poor during cold‐start, when the fuel was ignited and combusted without a coalbed, and when stoves failed to optimize air delivery due to specific loading and output conditions. During the cold‐start test section, the average BC emission rate was seven times higher than the overall average for Stove A, 10 times above the average for Stove B, and two times above the average emission rate for Stove C. Calculations of the Average Angstrom Absorption Exponent (AAE) of the exhaust aerosol showed little correlation with BC concentration. The results show that automation results in a quantifiable reduction in particular BC emissions.

Using the carbon balance method based on fuel-weighted average concentrations to estimate emissions from household coal-fired heating stoves

In China, household coal burning accounts for a large proportion of primary fine particulate matter (PM2.5), black carbon (BC), organic carbon (OC), polycyclic aromatic hydrocarbons (PAHs) and carbon monoxide (CO) emissions. Previous field investigations generally measured short-term emissions from heating coal stoves, which did not provide a full characterization of the actual conditions in most cases, or resulted in large uncertainties in the calculated emission factors (EFs). In this study, we propose a sampling design using a chimney partial-capture dilution system in the field measurement of household coal-fired heating stoves emissions during selected periods within the different burn phases and then using the carbon balance method (CBM) based on fuel-weighted average concentrations (FWAC) from the different burn phases to quantify emissions. We evaluated this proposed methodology by comparing the results with a laboratory total-capture dilution-tunnel system. Statistical analysis indicated that emissions measured during the selected burn cycle periods using the dilution sampling system can generally represent emissions at different burn phases; however, different dilution ratios can affect EFs for PM2.5 and OC. EFs of air pollutants derived by CBM with FWAC are more representative of the actual emissions than simple average concentration (SAC) and time-weighted average concentrations (TWAC). In the field application, to quantify FWAC, it is suggested to determine the ratio of power in the jth burn phase (Pj) to that in the high power phase (PH) of the stove, i.e., Pj/PH values with the calorimeter. If measured Pj/PH values are not available, the recommended value in this study is also suggested.

Realistic operation of two residential cordwood-fired outdoor hydronic heater appliances—Part 2: Particle number and size

ABSTRACT The use of wood as a fuel for home heating is a concern from an environmental health and safety perspective as biomass combustion appliances emit high concentrations of particulate matter. Wood burning significantly contributes to wintertime particulate matter concentrations in many states in the northern United States. Of particular concern are outdoor wood-fired hydronic heaters. These devices are concerning as they tend to have very large combustion chambers and typical use patterns can result in long periods of low output, which result in an increased particulate matter emission rate relative to high heat output operating conditions. In this study, the performance of two hydronic heaters operating under different combustion conditions, including four different heat output categories approximately corresponding to categories I–IV denoted in Environmental Protection Agency Method 28 Outdoor Wood-fired Hydronic Heaters, and during start-up and reloading events were investigated. Measurements of flue gas particulate number concentration and size for particles with aerodynamic diameters between 0.006 and 10 µm were made using a dilution sampling system. The measured particle number concentration in the flue gas was between 0.71 and 420 million particles per cubic centimeter and was dependent on fuel loading and heat output. For each hydronic heater tested, the highest average particle concentration was found at the beginning of each test during the cold-start condition. Additionally, the majority of the particles had aerodynamic diameters less than 0.100 µm (particles of this size made up between 64% and 97% of all particles) and less than 1% of all particles had aerodynamic diameters greater than 1 µm for all phases. For particles in the accumulation mode, between 0.100 and 1 µm, the mean particle diameter was dependent on fuel loading and heat output. Implications: In this work, we provide information on the particle number concentration and particle size of emissions from outdoor cord- wood-fired hydronic heaters. Wood-fired hydronic heater data is sparsely available compared to wood stove data. Thus, additionaldata from this source help to inform the work of modelers and policy makers interested in hydronic heaters. The test method used in this work is also novel, as it is more inclusive of real-world use cases than the current certification method. Our data helps to validate the test method and allows for comparisons between real-world use case scenarios, and idealized test cases.

Characterization of in-stack particulate emissions from residential wood hydronic heater appliances under different combustion conditions

ABSTRACT In the current work, we provide measurements of size-resolved particle number concentration (PNC), particle mass concentration (PMC), lung-deposited surface area (LDSA), and black carbon (BC) concentration for three biomass fired hydronic heaters during operation in four different combustion conditions. The appliances include one woodchip-fueled hydronic heater and two outdoor cordwood-fueled hydronic heaters. The operating conditions included startup, low output, high output, and burnout. Measurements were made using a custom dilution sampling system and a suite of commercially available, time-resolved, ambient aerosol measurement instrumentation. The PNC, as measured using an Dekati Electrical Low Pressure Impactor+ (ELPI), had operating condition mean values ranging between 4.1 and 52 million particles per cubic centimeter (#/cm3). The highest reported PNC occurred during the startup condition in all cases. Calculating the particle size distribution measured across each operating phase for the same instrument gave geometric mean diameters (dg ) in the range of 0.080–0.256 µm. The largest dg per appliance was nearly always attributable to the startup condition (for hydronic heater 1, startup dg ranked second). We did not observe the same trends when we transformed the ELPI PNC to PMC and particle surface area concentration estimates across operating conditions, suggesting PNC and dg are highly variable. Furthermore, simultaneous measurements of PNC, PMC, and PSAC using instrumentation with different working principles gave varying results, potentially suggesting that particles of different composition and morphology are produced under different combustion conditions.Implications: In this work we compare the results from testing of 3 biomass fired hydronic heaters including one chip-fired appliance and two cordwood-fired appliances. The emissions from these appliances were made across four operating conditions and using three different non-regulatory emissions metrics. This work: describes the difference between chip and cordwood fired units and the effect of operating condition on emissions across the three emissions metrics.

Characterization and Risk Assessment of Airborne Polycyclic Aromatic Hydrocarbons From Open Burning of Municipal Solid Waste

In order to reveal the pollution characteristics and risk level of polycyclic aromatic hydrocarbons (PAHs) exposed to air from open burning in China, PM2.5 samples were collected from the open burning of different types of municipal solid waste (MSW). The component of MSW differed from plastics, paper, wood and bamboo, and mixed garbage. A flue gas dilution sampling system was employed to simulate open burning testing on MSW samples from different functional urban areas. Emission characteristics and health risk assessments of PAHs in PM2.5 were analyzed. The results showed that the 16 PAHs were detected ranged from 16.0 to 10,386.9 ngm−3. The total PAH concentration of wood and bamboo wastes was the highest (24,512.1 ngm−3), while that in plastics was the lowest (4,084.7 ngm−3). Speciation composition of PAHs in PM2.5 with high-molecular-weight PAHs was dominant compared to low-molecular-weight PAHs. Health risk assessment showed that the proportion of samples with the lifelong lung carcinogenic risk value greater than 10–6 was 68.7% of the totals, most of the PAHs in PM2.5 had a certain risk of cancer. The speciation of Bap posed the greatest health risks to adults and children. The carcinogenic sequence of four components of wastes was as follows: wood and bamboo &amp;gt; mixed garbage &amp;gt; paper &amp;gt; plastics and the risk for adults was about 2.26 times higher than for children. Totally, the PAHs speciation of BaP, DBahA, BbF, IcdP, BaA, BkF, and Chr in PM2.5 from the open burning of MSW can bring high carcinogenic risk to human health by respiratory exposure, and the risk value of adults is higher than that of children. The findings show the different conclusion with the results of related researches on the environmental effect of waste incineration power plants or incinerators. Therein, it can provide supplementary data to evaluate the impact of open burning of MSW on ambient air quality.

Neglected biomass burning emissions of air pollutants in China-views from the corncob burning test, emission estimation, and simulations

Corncob is one of the major biomass sources and widely adopted as fuel in rural China. However, only few studies have discussed the emissions from corncob burning. The negligence of corncob burning emissions has resulted in biased or even unreasonable biomass burning emission results. In this study, the emission factors (EFs) of corncob burning were measured by the burning test simulation and dilution sampling system. Then, the measured EFs, field surveys, and GEOS-Chem simulation were adopted to estimate the emissions from corncob burning. The EFs of fine particles (PM2.5), carbon monoxide (CO), sulfur dioxide (SO2), nitric oxide (NO), nitric oxides (NOX), ammonia (NH3), the totally measured 13 volatile organic compounds (TVOCs), organic carbon (OC), elemental carbon (EC) and the sum of water-soluble ions (Na＋, K＋, Mg2＋, Ca2＋, NH4＋, Cl－, NO3－and SO42－) (SWSI) for corncob were 7.95, 60.53, 0.29, 1.38, 3.46, 0.35, 3.91, 1.21, 0.19 and 0.53 g kg−1, respectively. The emissions of PM2.5, CO, SO2, NO, NOX, NH3, TVOCs, OC, EC and SWSI in 2014 were 312.20, 2377.1, 11.39, 54.19, 135.87, 13.74, 153.55, 47.52, 7.46 and 20.77 Gg, respectively. These emissions have the same change tendency, wherein the emission in 2014 were approximately 0.42, 0.50, 0.64 and 0.85 times those in 1992, 2002, 2007 and 2012, respectively. The comparison with other straw highlighted the considerable emissions of corncob burning in China. The biomass burning emissions have been substantially underestimated by 2.6%–36.2% in previous studies, wherein corncob burning emissions were not considered. Additionally, the GEOS-Chem simulation results showed that corncob burning produced much higher concentration values than corn straw burning. Our study provided credible evidence to confirm the important emission contributions of corncob burning to biomass burning. It can also help improve the biomass burning estimation and air quality modeling results in the future.

Study on CO2 Emission Characteristics of China VI Heavy Duty Diesel Engine

CO2 emission control is of great urgency, and the decrease of heavy-duty diesel engines’ CO2 emission is one of the significant methods to reduce CO2 emission. This paper uses a full-flow constantvolume dilution sampling system to experiment on the China VI heavy-duty diesel engine in order to measure CO2 emissions under WHTC and WHSC cycles and different loads, with studying the instantaneous emissions characteristics of CO2, post-processing effects on CO2 emissions, influence factors of CO2 emissions. The study found that the CO2 emissions before the post-treatment of the WHSC cycle are 37% higher than that of the WHTC cycle, while emissions of CO2 are 3.45% higher than that before post-treatment. Simultaneously, cold start increases the CO2 emissions of the heavy-duty diesel engines by more than 1%. Post-treatment still increases the CO2 emissions of heavy-duty diesel engines by 3.5%. In addition, CO2 emissions have different trends with power at different speeds. CO2 emissions get an incremental within 600rpm and 900rpm, which gradually becomes slower until it reaches the peak, as engine power increases; the CO2 emissions initially increase, followed by a decrease, and then continue to increase within 1000rpm and 1400rpm; the CO2 emissions are almost not affected by the speed within 1500rpm and 1900rpm.

Hourly emission estimation of black carbon and brown carbon absorption from domestic coal burning in China

Residential coal combustion (RCC) emission demonstrates obvious daily variation, while no real-time estimation of air pollutants from RCC has been reported, as the limitation of hourly activity data and emission factors. With a dilution sampling system, a high-precision electronic balance, and an Aethalometer Model AE33, a real-time monitoring platform for RCC emission was established. Hourly emission factors (EFs) of BC and absorption emission factors (AEFs) of BrC from eleven kinds of chunk coals and nine kinds of honeycomb coals burning in China were obtained. The monthly and hourly coal consumption amounts were calculated with the activity data from literature reviews and a field survey. The first hourly BC and absorption cross section of BrC emission inventories from RCC were established in China. The historical emission trends (2003–2017) indicated that the policy has rapidly controlled the emission of BC and ACSBrC from RCC in urban area (26.7% and 31.8% decreased, respectively in 2013). While in rural areas, their emission continually increased by 1.2% ~ 5.3% until more strict law enacted in 2017. Emissions of BC and ACSBrC in winter seasons were 60.1 Gg and 1064.1 Gm2, which accounted for 54.3% and 55.1% of the total BC and ACSBrC emissions correspondingly. The peak values of hourly emission of BC and ACSBrC (in 370 nm) normally appeared at 19:00–23:00, accounting for 43.0% and 41.5% of their total daily emission. The low emission periods were at cooking times including 7:00, 12:00, and 17:00 of a day and the whole emission of BC and ACSBrC for the three periods accounted for 1.8% and 2.3% of their daily emission. This high-resolution BC and ACSBrC emission inventories can be useful for future modeling works on the formation and evolution of a haze event, the smoke aging and transportation, as well as corresponding climate and human health effects.

Source profiles and emission factors of organic and inorganic species in fine particles emitted from the ultra-low emission power plant and typical industries

Accurate source markers, source profiles and species-based emission factors (EFs) are currently the key limitations for source apportionment and emission inventory researches. Fine particles (PM2.5) were collected from stack gases of eight types of stationary sources with a dilution sampling system. The mass percentages and EFs of 89 kinds of chemical species in PM2.5 including water-soluble ions, elements, carbonaceous species and molecular organic species were obtained. Results showed that water-soluble ions (8%–54%) and elements (5%–45%) were the dominant chemical species. Palmitic acid (0.19%–0.62%) and stearic acid (0.21%–0.59%) were the most abundant organic species. PM2.5 source profiles of the eight sources were different from each other with the coefficient of divergence values all higher than 0.4. The addition of organic species could help to further distinguish them. The indicatory chemical components and specific species ratios were obtained by both a statistical equation and randomForest. These indicatory chemical components (e.g. F− for glass factory) and species ratios (e.g. K+/Mg2+ & OC/Mg for pharmaceutical factory) improved the current knowledges of their indicatory performance in source identification of ambient PM2.5. The EFs of PM2.5 from the eight stationary sources ranged from 0.019 to 51.6 kg t−1 of fuel used. The EFs of PM2.5 from the pharmaceutical factory were about 70–2600 times higher than other seven types of sources due to the lack of dust-removing devices. Certain EFs measured in this study were about 10–36,000 times lower than corresponding EFs estimated in previous studies which didn't perform field measurements, indicating the necessity for improving emission inventories continuously. This study contributes to identifying emission sources of PM2.5 especially for subtypes of stationary sources and to establishing species-based emission inventories.

Nanostructure and reactivity of soot particles from open burning of household solid waste

The main purpose of this work was to quantify and characterize chemically and morphologically the emission of soot particles from the open burning of several common solid waste including paperboard, wood, peel, chemical fiber, polyethylene (PE) and polyvinyl chloride (PVC). The experiment was conducted in a laboratory-scale open-burning combustor with a dilution sampling system to obtain soot particles. The thermogravimetric profiles (TGA) showed an increasing order of oxidation reactivity: PE > PVC > fiber > paper ≈ peel > wood. High resolution transmission electron microscopy (HRTEM) images revealed more detailed information about the morphology and the particle size of soot aggregates. Subsequent quantification of nanostructure by fringe analysis showed that plastics generated soot particles with the looser carbon layers with higher tortuosity compared to the three kind of biomass. Raman spectroscopy further confirms the observed differences. In addition, wood soot exhibited the highest content of C–OH group (17.5%) among the six samples (X-Ray photoelectron spectroscopy, XPS), whereas PE and PVC soot exhibited the highest absorption peaks of aliphatic C–H groups (Fourier transform infrared spectroscopy, FTIR). Comparative analysis revealed that the interlayer distance was more important on the evaluation of reactivity than soot morphologies. The present work concluded that the physiochemical characteristics of soot particles releasing during open burning are strongly depending on waste composition and provided new data for the understanding of soot emissions from open burning.

Theoretical equilibration time is supported by measurement study of residence time at dilution sampling on fine particulate matter emissions from household biofuel burning

Household biofuel burning contributes a large proportion of fine particulate matter (PM2.5), black carbon (BC), and organic carbon (OC) emissions in many parts of the world. Dilution sampling has been widely used to characterize PM2.5 emitted from biofuel burning. The residence time in the dilution chamber is a key parameter for accurate sampling. However, residence time has not yet been adequately characterized for biomass combustion. In this work, we investigated the effects of residence time of dilution sampling on PM2.5 emissions from a typical Chinese household stove burning typical biofuels including three major crop wastes and one type of wood. The filter based measurements indicated that the emission factors for PM2.5 and its main chemical components such as OC, EC, Cl−, and K+ did not vary with the residence time over the range of 1–80 s. Theoretical estimation of average time scale for achieving dynamic equilibrium (τs) between the gas and particle phase in the dilution sampling system was less than 1 s. Both the measurement study and theoretical simulations indicated that dilution sampling with a residence time of 1s can provide adequately reliable results for PM2.5 emissions from biofuel burning under the condition of these experiments. A simple way to estimate the equilibration time based on measured average PM2.5 concentration was proposed. Recommendations are provided for the residence time for dilution sampling of accurate measurements of PM2.5 emissions from biofuel burning.

Experimental study on the formation of ultrafine particulate matters (PMs) during pulverized coal (PC) char combustion in O2/N2 and O2/CO2 atmospheres

Under the force of increasingly strict emission standard of particulate matters (PMs) and serious haze in China, further understanding of the formation of ultrafine PMs during coal combustion is crucial. In this work, the formation characteristics of ultrafine PMs during pulverized coal (PC) char combustion in O2/N2 and O2/CO2 atmospheres were investigated through a high-temperature drop tube furnace (DTF) with a two-stage dilution sampling system and a 14-stage electrical low pressure impactor (ELPI+). Results showed that in both number-based and mass-based particle size distribution (PSD) the peaks of ultrafine PMs located nearby 0.2 μm under all experimental atmospheres including O221%/N279%, O221%/CO279%, O227%/CO273% and O233%/CO267% (O21N79, O21C79, O27C73 and O33C67). And the peak values increased with the increase of O2 concentration in O2/CO2 atmospheres because of the high char combustion temperature at elevated O2 level. However, the mass and number concentration of ultrafine PMs in O2/CO2 atmospheres reduced significantly compared with these in O2/N2 atmosphere. When O21N79 atmosphere switched to O21C79, O27C73, O33C67 atmosphere, the mass concentration of ultrafine PMs reduced by 80.90%, 76.58% and 14.31%, and the number concentration reduced by 74.16%, 63.17% and 10.50%, respectively. Furthermore, the total mass of the ultrafine PMs was determined by the mass of the ultrafine PMs with larger particle size, whereas the total number of ultrafine PMs was determined by the number of the ultrafine PMs with smaller particle size. In this work, the ultrafine PMs with the aerodynamic size smaller than 0.3 μm were collected on the 1st to 7th impactor surfaces of the ELPI+. Among the ultrafine PMs, the particles on the 7th impactor (PMs with the superior limit of ultrafine PMs size) accounted for more than 94.8% of the total ultrafine PMs by mass, but less than 2.3% of the total ultrafine PMs by number; The particles deposited on the 1st impactor (PMs with the detectable minimum size of ultrafine PMs) accounted for more than 79.6% of the total ultrafine PMs by number, but less than 0.4% of the total ultrafine PMs by mass. In addition, PM0.1 which accounted for 96% of the total number of the ultrafine PMs was analyzed for chemical composition by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Results showed that the prominent components of PM0.1 were Ca, Na, and Si in both O2/N2 and O2/CO2 atmospheres. However, compared with O2/N2 atmosphere, Na, Si, Al, and Fe were more enriched in PM0.1 in O2/CO2 atmospheres.

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.

Understanding the emission pattern and source contribution of hazardous air pollutants from open burning of municipal solid waste in China

The open burning of municipal solid waste (MSW) is common in China. Therein, low–temperature anoxic combustion results in the emission of hazardous air pollutants. This study employed a dilution sampling system to conduct open burning testing on MSW samples from different functional urban areas. Additionally, modified combustion efficiency was used to distinguish smoldering and flaming combustion in two of the most common open burning practices in China: pile–up burning and barrel burning. The sampled pollutants included gaseous pollutants (e.g., CO2, CO, SO2, and NOx) and fine particles (PM2.5). This study also analyzed the carbonization compounds, 9 water–soluble ions, and 8 toxic heavy metals in PM2.5. Emission factors of air pollutants from open burning of different MSW compositions and burning modes were determined. The composition of PM2.5 from MSW open burning comprised average 43.9%, 22.5%, and 0.4% of organic carbon (OC), water–soluble ions, and toxic heavy metals (THMs), respectively. OC was found to be the primary component of PM2.5. Based on localized emission factor database, the emissions and source contribution of open burning of MSW in China were quantified. The open burning of MSW can contribute averaged 8.7%, 16.7%, 3.8%, 1.3% of PM2.5, OC, THMs, and gaseous air pollutants of reported emissions of anthropogenic sources, respectively. This work can complement current anthropogenic emission inventory and assist policy–making.

Emission Characteristics of IVOCs from the Combustion of Residential Solid Fuels and the Impact of Burning Temperature

Intermediate-volatility organic compounds (IVOCs) are important precursors of secondary organic aerosols that have received much recent attention; however, there is a lack of emission data for IVOCs from combustion sources, especially for residential solid fuel combustion. In this study, two bituminous coals with different geological maturity (XZ and LW) and two biomass types (rice stalk and pinewood) were tested at seven temperature points (300-900℃ with an interval of 100℃) using a quartz tube furnace together with a dilution sampling system. The results showed that the averaged emission factor for IVOCs from biomass combustion[(483±182) mg·kg-1] was 2.5 times higher than that of bituminous coal combustion (190±108) mg·kg-1. The remaining unresolved complex mixture (UCM) dominated the IVOC content for both biomass and coal combustions (81%±11% and 68%±6%, respectively). The fraction of normal and branched alkanes for biomass combustions was lower than for coal combustion, while the fraction of aromatics was higher. The effect of temperature on the emission of IVOCs and their composition was significantly different between the two types of fuel. The emission factor for IVOCs from coal (using LW as an example) at 500℃[(340±113) mg·kg-1] was 5.4 times higher than at 900℃[(63±15) mg·kg-1], while two comparable peaks are observed at 400-500℃ and 800-900℃. As the combustion temperature increased, the proportion of aromatic hydrocarbons in pinewood IVOCs increased from 1% to 29%, while the remaining UCM decreased from 92% to 61%. However, there was little variation for coal combustion. The effects of fuel type and temperature on the emission of IVOCs were further explained with respect to the modified combustion efficiency (MCE).

Size-segregated emission factors and health risks of PAHs from residential coal flaming/smoldering combustion

Residential coal combustion is one of the main sources of ambient polycyclic aromatic hydrocarbons (PAHs). Updating its emission estimation is limited by the shortages of emission factors, especially for them in different particle sizes and from different combustion conditions. PAH emission factors (EFs) for nine size-segregated particle segments emitted from smoldering and flaming combustion of residential coals (four kinds of raw coals (RCs) and three kinds of honeycomb coal briquettes (HCBs)) were obtained in China, using a dilution sampling system. EFs of PAHs for the flaming and smoldering of HCB ranged from 1.32 to 2.04mgkg-1 and 0.35 to 5.36mgkg-1, respectively. The EFs of PAHs for RC flaming combustion varied from 0.50 to 218.96mgkg-1. About 53.5-96.4% and 47.4-90.9% of PAHs concentrated in PM2.1 and PM1.1, respectively. Different fuel types and combustion conditions strongly affected the PAH EFs. The PAH EF for the RC was 0.3 times that for HCB in Guizhou, which implied that PAH EFs for RC combustion were not always higher than those from HCB burning. For different combustion conditions, the PAH EFs from flaming were more than 2.5 times higher than those from smoldering for HCB except in the Anhui region. Results indicated that current PAH EFs may not be universal, which may bias the establishment of control policies for toxic pollutants emitted from domestic coal burning. On average, 73.2 ± 15.5% of total PAH potential toxicity risks were concentrated in submicron particles. More size-segregated PAH EFs for residential coal combustion should be investigated considering combustion conditions with a uniform sampling method in China.

Characterization of PM10 and PM2.5 Source Profiles for Emissions from Nonmetal Mineral Products Manufacturing Processes

In view of the insufficient source profiles for emissions from nonmetal mineral products manufacturing processes in China, a dilution sampling system was used to collect PM10 and PM2.5 samples from glassmaking, ceramics, and firebrick manufacturing sources between February and June of 2017. The characteristics of 50 chemical components in the samples were studied to identify source profiles. The results showed that the dominant composition of particulate matter in glassmaking plant profiles was Na, with percentages ranging from 9.2% to 18.5%. Ceramics profiles were enriched in Al, Si, Ca, and Fe, with percentages ranging from 1.7% to 8.7%. Refractory brick and shale manufacturing process profiles were characterized by high abundances of SO42- (36.9%-48.1%) and NH4+ (7.7%-17.0%). Chemical components in the source profiles varied with the different fuel types and desulfurization, denitrification, and dedusting methods. The coefficients of divergence (CD) between PM2.5 and PM10 from the same process were similar except for the results from the shale manufacturing process (CD values>0.3), thus indicating that the elements profiles of PM2.5 might be similar to those in PM10. Profiles of the same particle size from different processes were significantly different from one another, with CD values ranging from 0.42 to 0.76. The CD values for float glass and medicinal glass, and the CD values for the two ceramic enterprises were relatively small. The distributions of weighted differences (R/U ratios) were used to compare the differences of components between the source profiles, and results showed that the identified components for glass manufacturing, ceramic manufacturing, fireproof bricks, and page rock bricks were Na and As, Al and Ti, NO3- and NH4+, and SO42- and NH4+, respectively.

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 Characteristics and Chemical Components of PM2.5 from Open Burning of Municipal Solid Waste

Source emission measurements were employed to investigate open burning of municipal solid waste (MSW). Both barrel and natural pile-up burning of MSW were investigated using a self-designed dilution sampling system. PM2.5 was collected for three types of waste, including rubber and plastic, paper, and wood and bamboo. Then, components in the samples were analyzed and emission factors of PM2.5, organic carbon (OC), elemental carbon (EC), water-soluble ions and inorganic elements were calculated. The PM2.5 emission factor was highest for wood and bamboo, and lowest for paper, and was calculated to be (7.44±0.76) g·kg-1 and (2.72±0.52) g·kg-1, respectively. Barrel burning resulted in much higher pollutant emissions. The PM2.5 emission factor for barrel burning was 2.5-3.5 times that of natural pile-up burning. OC and EC were the main components of PM2.5, with a proportion of 46.6%-67.2%. MSW composition had a greater effect on the OC/EC ratios than burning mode. The ratios could be helpful in the analysis of the emission contributions of different MSW components. The proportions of NH4+ and Cl- were the highest in water-soluble ions, accounting for 2.28%-6.35% and 1.04%-14.31%, respectively. Among inorganic elements, Ca, K, Fe, and Ba showed high emission factors. The emission factor of Zn was the highest among heavy metals, and other elements such as Cu, Cr, Sb, and Pb were also enriched. Zn emission was mainly determined by the burning mode; emissions from barrel combustion were approximately 20 times more than that of natural pile-up burning.