Chemical characterization and source apportionment of aerosol over mid Brahmaputra Valley, India

Removal of airborne particulate matter by evergreen tree species in Dhaka, Bangladesh

Urban air quality stands as a pressing concern in cities globally, with airborne particulate matter (PM) emerging as a significant threat to human health. An investigation was carried out to examine the potential of four prevalent evergreen roadside tree species grown at different locations in Dhaka to capture PM using their leaves. The distribution of PM by mass and quantity in Dhaka are presented for the first time for Bangladesh and these results will also be applicable to countries with similar climates and tree species. Separate gravimetric analyses were carried out to quantify PM in three different size ranges (0.2-2.5 μm, 2.5-10 μm, and 10-100 μm) accumulated on surfaces and trapped within waxes by using the rinse and weigh method. The method is validated for the first time through SEM-EDX analysis, which confirmed that the increase in weight from chloroform-rinsed leaves was exclusively attributable to particle deposition on the filter. The chemical composition of the deposited PM2.5 was analyzed quantitatively by determining the concentration of twenty-five trace elements employing ICP-MS. SEM-EDX analysis revealed the significance of leaf microstructural traits in effectively capturing PM. Significant variations in the deposition of PM were found among different species for two PM categories (surface PM and wax-embedded PM) and three size fractions (large, coarse, and fine) (one-way ANOVA; p < 0.05). The quantity of wax retained on the foliage of trees documented in these locations also varied (p < 0.05). Among the species studied, Ficus benghalensis demonstrated a greater ability to retain PM. Mangifera indica was identified to be the most efficient collector of wax-related PM and appears to be the ideal species for traffic-heavy areas distinguished by high concentrations of organic compounds from vehicle emissions.

In-depth characterization of particulate matter in a highly polluted urban environment at the foothills of Himalaya-Karakorum Region

In recent years, the rising levels of atmospheric particulate matter (PM) have an impact on the earth's system, leading to undesirable consequences on various aspects like human health, visibility, and climate. The present work is carried out over an insufficiently studied but polluted urban area of Peshawar, which lies at the foothills of the famous Himalaya and Karakorum area, Northern Pakistan. The particulate matter with an aerodynamic diameter of less than 10 µm, i.e., PM10 are collected and analyzed for mineralogical, morphological, and chemical properties. Diverse techniques were used to examine the PM10 samples, for instance, Fourier transform infrared spectroscopy, x-ray diffraction, and scanning electron microscopy along with energy-dispersive x-ray spectroscopy, proton-induced x-ray emission, and an OC/EC carbon analyzer. The 24 h average PM10 mass concentration along with standard deviation was investigated to be 586.83 ± 217.70 µg/m3, which was around 13 times greater than the permissible limit of the world health organization (45 µg/m3) and 4 times the Pakistan national environmental quality standards for ambient PM10 (150 µg/m3). Minerals such as crystalline silicate, carbonate, asbestiform minerals, sulfate, and clay minerals were found using FTIR and XRD investigations. Microscopic examination revealed particles of various shapes, including angular, flaky, rod-like, crystalline, irregular, rounded, porous, chain, spherical, and agglomeration structures. This proved that the particles had geogenic, anthropogenic, and biological origins. The average value of organic carbon, elemental carbon, and total carbon is found to be 91.56 ± 43.17, 6.72 ± 1.99, and 102.41 ± 44.90 µg/m3, respectively. Water-soluble ions K+ and OC show a substantial association (R = 0.71). Prominent sources identified using Principle component analysis (PCA) are anthropogenic, crustal, industrial, and electronic combustion. This research paper identified the potential sources of PM10, which are vital for preparing an air quality management plan in the urban environment of Peshawar.

Optimization of syngas production from co-gasification of palm oil decanter cake and alum sludge: An RSM approach with char characterization

The study explores co-gasification of palm oil decanter cake and alum sludge, investigating the correlation between input variables and syngas production. Operating variables, including temperature (700-900 °C), air flow rate (10-30 mL/min), and particle size (0.25-2 mm), were optimized to maximize syngas production using air as the gasification agent in a fixed bed horizontal tube furnace reactor. Response Surface Methodology with the Box-Behnken design was used employed for optimization. Fourier Transformed Infra-Red (FTIR) and Field Emission Scanning Electron Microscopic (FESEM) analyses were used to analyze the char residue. The results showed that temperature and particle size have positive effects, while air flow rate has a negative effect on the syngas yield. The optimal CO + H2 composition of 39.48 vol% was achieved at 900 °C, 10 mL/min air flow rate, and 2 mm particle size. FTIR analysis confirmed the absence of C─Cl bonds and the emergence of Si─O bonds in the optimized char residue, distinguishing it from the raw sample. FESEM analysis revealed a rich porous structure in the optimized char residue, with the presence of calcium carbonate (CaCO3) and aluminosilicates. These findings provide valuable insights for sustainable energy production from biomass wastes.

Atmospheric aerosol chemistry and source apportionment of PM10 using stable carbon isotopes and PMF modelling during fireworks over Hyderabad, southern India

This study examined the influence of fireworks on atmospheric aerosols over the Southern Indian city of Hyderabad during festival of Diwali using mass closure, stable carbon isotopes and the EPA-PMF model. Identification of chemical species in day and night time aerosol samples for 2019 and 2020 Diwali weeks showed increased concentrations of NH4+, NO3-, SO42-, K+, organic carbon (OC), Ba, Pb and Li, which were considered as tracers for fireworks. PM10 source apportionment was done using inorganic (trace elements, major ions) and carbonaceous (organic and elemental carbon; OC & EC) constituents, along with stable isotopic compositions of TC and EC. K+/Na+ ∼1 and K+nss/OC > 0.5 indicated contribution from fireworks. High NO3-, NH4+, Na+, Cl- and SO42- suggested the presence of deliquescent salts NaCl, NH4NO3 and (NH4)2SO4. TAE/TCE >1 suggested H+ exclusion, indicating possible presence of H2SO4 and NH4HSO4 in the aerosols. Ba, Pb, Sb, Sr and Fe increased by 305 (87), 12 (11), 12 (3), 3 (2) and 3 (4) times on Diwali nights, compared to pre-Diwali of 2019 (2020), and are considered as metallic tracers of fireworks. δ13CTC and δ13CEC in aerosols closely resembled that of diesel and C3 plant burning emissions, with meagre contribution from firecrackers during Diwali period. The δ13CEC was relatively depleted than δ13CTC and δ13COC. For both years, δ13COC-EC (δ13COC - δ13CEC) were positive, suggesting photochemical aging of aerosols during long-range transport, while for pre-Diwali 2019 and post-Diwali 2020, δ13COC-EC were negative with high OC/EC ratio, implying secondary organic aerosols formation. High toluene during Diwali week contributed to fresh SOA formation, which reacted with precursor 12C, leading to 13C depletions. Eight-factored EPA-PMF source apportionment indicated highest contribution from residue/waste burning, followed by marine/dust soil and fireworks, while least was contributed from solid fuel/coal combustion.

Bottom-up and top-down approaches for estimating road dust emission and correlating it with a receptor model results over a typical urban atmosphere of Indo Gangetic Plain

To investigate the emission and concentration of PM10 and PM2.5-related road dust over Agra, a typical semi-arid urban atmosphere of the Indo Gangetic Plain (IGP), a fine-resolution emission inventory and receptor modeling-based source apportionment was undertaken for the year 2019. On-road, the silt load of Agra (7-55 g/m2 of the road) was found to be 10 to 50 times higher than that reported in advanced countries. The silt load over Agra varied widely depending on road conditions, long-range transport, and land-use pattern. Depending on the silt load, land-use and fleet averaged weight, the annual emission factor for road dust was estimated as 14.3 ± 3.2 (PM10) and 4.4 ± 1.4 (PM2.5) gm/VKT (vehicle kilometer travel). PM10 emission of road dust alone contributed 80 % (29 ± 6 t/d) to the total emission of PM10 and 68 % (9 ± 3 t/d) to PM2.5 of the city with the maximum emission being in industrial areas. Chemical analysis of ambient PM10, PM2.5, and road dust samples showed that the road dust was enriched with geogenic components and was in good agreement with the road dust profile identified from the positive matrix factorization receptor model. The model estimated contribution of road dust (summer and winter combined) to PM10 and PM2.5 ambient air levels was 28 % (67 μg/m3) and 23 % (27 μg/m3) respectively. Summer showed a larger road dust contribution than winter due to strong surface wind and dry road conditions. Results have revealed that the emissions and concentrations of road dust are closely interrelated with road conditions (silt load), land-use patterns, VKT, weight of the vehicles, and micrometeorological conditions. The large road dust emission in IGP cities requires better road conditions and traffic management to curb the emission.

Mass, composition, and sources of particulate matter in residential and traffic sites of an urban environment

Present study aims to assess the mass, composition, and sources of PM₁₀ and PM_2.5 (particulate matter having aerodynamic diameter less than or equal to 10 and 2.5 µm aerodynamic diameter, respectively) in Vellore city. Seasonal samples collected in traffic and residential sites were analyzed for ions, elements, organic carbon (OC), and elemental carbon (EC). Source apportionment of PM₁₀ and PM_2.5 is carried out using Chemical Mass Balance, Unmix, Positive Matrix Factorization and Principal Component Analysis receptor models. Results showed that traffic site had higher annual concentration (PM_2.5 = 62 ± 32 and PM₁₀ = 112 ± 23 µg m^-3) when compared to residential site (PM_2.5 = 54 ± 22 and PM₁₀ = 98 ± 20 µg m^-3). Al, Ca, Fe, K, and Mg known to have crustal origin dominated the element composition irrespective of PM size and sampling site. Among ions, SO₄^2- accounted highest in both sites with an average of 70 and 60% to PM_2.5 and PM₁₀ ionic mass. Elemental carbon contribution to PM mass was found highest in traffic site (PM_2.5 = 17 to 23% and PM₁₀ = 8 to 10%) than residential site (PM_2.5 = 9 to 17% and PM₁₀ = 4 to 8%). Elements, ions, OC, and EC accounted 12, 28, 34, and 16% of PM_2.5 mass and 12, 21, 20, and 8% of PM₁₀ mass, respectively. Different sources identified by the receptor models are resuspended road dust, crustal material, secondary aerosol, traffic, non-exhaust vehicular emissions, secondary nitrate, construction, cooking, and biomass burning. Since Vellore is aspiring to be a smart city, this study can help the policymakers in effectively curbing PM.

A year-long study on PM2.5 and its carbonaceous components over eastern Himalaya in India: Contributions of local and transported fossil fuel and biomass burning during premonsoon

A year-long (March 2019-February 2020) study on the characterization of fine mode carbonaceous aerosols has been conducted over a high altitude urban atmosphere, Darjeeling (27.01°N, 88.15°E, 2200 m asl) in eastern Himalaya. The fine mode aerosol (PM_2.5; 41.7 ± 23.7 μgm^-3), total carbonaceous aerosols (TCA; 19.8 ± 7.7 μgm^-3), organic carbon (OC; 8.0 ± 3.9 μgm^-3) and elemental carbon (EC; 2.0 ± 0.9 μgm^-3) exhibited similar seasonal variability with the highest abundance during winter followed by premonsoon, postmonsoon and minimum in monsoon. The OC:EC varied over a range of 2.8-19.4 whereas the secondary organic carbon ranged between 1.9 and 17.1 μgm^-3 respectively. Higher PM_2.5 associated with higher winds and elevated mixing layer depth suggest a strong influence of regional and long-range transport. In addition to the usual morning and evening rush-hour peaks, the impact of low land plain regions driven by up-slope valley winds was observed for the carbonaceous components. A novel approach has been taken to find out the individual contributions from the local and transported fossil fuel, biomass burning, and biogenic sources to OC and EC during premonsoon. We observed that the local fossil fuel (43%) contributions dominated over the biomass burning (39%) for EC whereas the contributions of local biomass burning and the local fossil fuel were same (46%) for OC. EC exhibited a higher contribution (18%) from the regional/long-range transport compared to OC (8%). IGP and Nepal were found to be the maximum contributing long distant source regions for the carbonaceous aerosol loading over eastern Himalaya. Such individual source apportionment of carbonaceous aerosols over eastern Himalaya makes the study unique and first-ever of its kind and immensely helpful for building robust mitigation action plans.

On the techniques and standards of particulate matter sampling

Air pollution and its limits are regulated by the environmental protection agency of an individual country according to their National Ambient Air Quality Standards (NAAQS). Particulate matter (e.g., TSP, PM₁₀, and PM_2.5) is one of the important criteria pollutants of NAAQS. Their measurement methods are specified in NAAQS, and detailed technical descriptions are given in standards. This review focuses on the sampling and analysis techniques and methods in the context of PM samplers' design mentioned in countries specific PM measuring standards (e.g., EPA Part 50, CEN 12341, IS 5182(23), etc.) and their comparison wherever is necessary. It discusses, different designs of PM samplers mentioned in standards and its important components, e.g., size fractionators cutoff efficiency, PM sampler head design, flow measurement, and calibration, and also addresses the important issues that are the limitation of present standards. Our review reveals that most of the country-specific standards show common practice in measuring PM_2.5 using WINS impactor and VSCC cyclone as mentioned in EPA Part 50, except European Union (EU) standards, which has different design and parameters. For PM₁₀ measurement, sampler design is different in EU and Indian standards than that of U.S. EPA and other countries' standards, which is discussed in length here. All standards lack in pointing some inherent problems like change in D₅₀ cutoff of size fractionator of sampler under a high particle mass loading condition, which is common in countries like China and India. Other important issues where most of the standards lack include PM head design and specification, a key component of PM sampler on which the mass measurement results are largely dependent.Implications: The review paper discusses the air quality standards compliances of different countries and their comparisons. It focuses on the sampling and analysis techniques in context of PM samplers' design mentioned in countries specific PM measuring standards, and also addresses the important issues that are not mentioned in standards. Therefore, the discussions and findings of the review may be very useful while revising the existing air quality standards of different countries and to fill the research gap in this domain. Further, we have discussed several technical issues described in standards related to PM sampling which may be very helpful for PM sampler designing or modification in current designs as per the prevailing ambient conditions of a country.

Variations in the concentration, source activity, and atmospheric processing of PM2.5-associated water-soluble ionic species over Jammu, India

Concentrations, sources, and atmospheric processing of water-soluble ionic species associated with PM_2.5 collected from 2015 to 2017 were studied in Jammu, an urban location in the North-Western Himalayan Region (NWHR). Being ecologically sensitive and sparsely studied for dynamics in PM_2.5 and associated WSIS, the present study is important for developing robust air pollution abatement strategies for the air-shed of NWHR. Twenty-four hourly PM_2.5 samples were collected on weekly basis at a receptor site and analyzed for WSIS using ion chromatography system. On annual basis, total sum of WSIS (ΣWSIS) contributed about 28.5% of PM_2.5, where the contribution of sulfate-nitrate-ammonium, a proxy for secondary inorganic aerosols (SIA), was found to be 18.7% of PM_2.5. The ΣWSIS and PM_2.5 concentration showed a seasonal cycle with the maximum concentration during winters and the minimum in summers. Mass fraction of ΣWSIS in PM_2.5 showed an anti-phase seasonal pattern indicating more source activity during summers. Season-wise, dominant WSIS constituting PM_2.5 were NO₃^-, SO₄^2-, NH₄⁺, and K⁺ during winters; whereas summer was marked with dominant contributions from SO₄^2-, NH₄⁺, Ca²⁺, and K⁺. Seasonal variability exhibited among SIA constituents underscored the crucial role of air temperature and relative humidity regime. It was observed that nss-K⁺ + NH₄⁺ were sufficient to neutralize most of the acidic species arising from precursor gases (NO_x and SO_x). Using principal component analysis, five major sources and processes, viz. (a) biomass burning activities, (b) secondary inorganic aerosol formation, (c) input from re-suspended dust, (d) transported dust, and (e) fertilizer residue, were identified for the emissions of PM_2.5-associated WSIS over Jammu. In future studies, impacts of dry and/or wet deposition of aerosol-associated WSIS on the crop productivity in the region should be studied.

Seven-year study of monsoonal rainwater chemistry over the mid-Brahmaputra plain, India: assessment of trends and source regions of soluble ions

This work is a 7-year study of monsoonal rainwater chemistry (n = 302), over mid-Brahmaputra plain during 2012 to 2018. The samples were analyzed for major chemical parameters viz. pH, electrical conductivity (EC), and ions (SO₄^2-, NO₃^-, Br^-, Cl^-, F^-, Mg²⁺, Ca²⁺, K⁺, NH₄⁺, Na⁺, and Li⁺) to assess the chemistry. The mean pH of rainwater varied among the years, which was maximum in 2018 (6.18 ± 0.72) and minimum in the year 2014 (5.39 ± 0.54), and the variations were significant at p < 0.0001. Ridgeline plots were drawn to visualize interannual variations, which revealed that Ca²⁺ was the dominant cation in the early years, whereas NH₄⁺ prevailed in the latter years. Mann-Kendall analysis and Sen's slope statistical tests were employed, and it was found that all the ions showed positive S values indicating increasing trends. Enrichment factors (EF) of K⁺, SO₄^2-, and NO₃^- were found to be high with respect to both soil and seawater suggesting the influence of emissions from fossil fuel and biomass burning in the chemistry of rainwater. Principal component analysis (PCA) was applied to identify the sources of rain constituents, and five factors were obtained explaining crustal dust, biomass burning, fossil fuel combustion, agricultural emissions, and coal burning as possible sources. Airmass back trajectory clusters and Potential Source Contribution Function (PSCF) were computed by application of HYbrid Single-Particle Lagrangian Integrated Trajectory model to appreciate the terrestrial influence on the chemistry. The results indicated inputs from both local and regional dust and anthropogenic constituents that influenced the monsoonal rainwater chemistry over Brahmaputra Valley.

Determination and assessment of elemental concentration in the atmospheric particulate matter: a comprehensive review

The elemental concentrations of atmospheric particulate matter (PM) have a detrimental effect on human health in which some elemental species have carcinogenic nature. In India, significant variations have found in the practices adapted from sampling to analysis for the determination and assessment of the elemental concentration in PM. Therefore, Indian studies (2011-2020) on the related domain are summarized to impart consistency in the field and laboratory practices. Further, a comparative analysis with other countries has also been mentioned in the relevant sections to evaluate its likeness with Indian studies. To prepare this study, literature has been procured from reputed journals. Subsequently, each step from sampling to analysis has thoroughly discussed with quality assurance and control (QA/QC) compliance. In addition, a framework has been proposed that showed field and laboratory analysis in an organized manner. Consequently, this study will provide benefit to novice researcher and improve their understanding about the related subject. Also, it will assist other peoples/bodies in framing the necessary decisions to carry out this study.

Biomonitoring of metallic air pollutants in unique habitations of the Brahmaputra Valley using moss species-Atrichum angustatum: spatiotemporal deposition patterns and sources

In this paper, we have evaluated the bioaccumulation of metals by Atrichum angustatum, which is a readily available moss species in the Brahmaputra valley, India. A systematic investigation of metallic pollutants in the atmosphere was carried out using A. angustatum as a biomonitor collected from representative locations during three seasons viz. winter, pre-monsoon, and monsoon (n = 99) during the year 2018. The study was done in four unique habitations of the Brahmaputra Valley, which were further divided into three landuse areas: residential, roadside, and industrial. The highest accumulations were seen against Ca, Mg, Zn, and Fe. The calculated contaminant factors and ecological risk indices suggest that the Brahmaputra Valley is mostly contaminated by Cr, Zn, Cu, Ni, and Pb, and these metals pose a maximum ecological risk. The accumulation trend of metallic pollutants was site-specific, but most metals showed positive seasonal accumulation. A significant difference in spatial and seasonal accumulation patterns was specific to metal species. Principal component analysis (PCA) and inter-species correlations revealed that the air quality of Brahmaputra valley was greatly affected by coal burning, vehicular emission, biomass burning, road dust, and crustal dust. Finally, the study led us to the conclusion that A. angustatum can serve as a potential biomonitor for metallic pollutants.

Emerging Major Role of Organic Aerosols in Explaining the Occurrence, Frequency, and Magnitude of Haze and Fog Episodes during Wintertime in the Indo Gangetic Plain

Aerosols are an important part of Earth's atmosphere. They can absorb, scatter, or reflect the incoming solar radiation, which results in heating or cooling of Earth, thus impacting its climate. It affects the health of exposed human population adversely, reduces visibility, disturbs environmental systems, and causes material damage. This study summarizes the research carried out to understand the role of aerosol load and its physicochemical characteristics on occurrence, frequency, and magnitude of haze and fog events during wintertime within the Indo Gangetic Plain (IGP) in the past decade. For most species, the highest concentration was measured during foggy events at night-time over the winter season. A few species such as water-soluble organic and inorganic carbon (WSOC and WSIC), K⁺, SO₄ ^2-, and NO₃ ^-, owing to their hygroscopic nature, were efficiently scavenged, resulting in their lower concentration within the interstitial aerosol during fog episodes. Oligomerization with hydroxy and carbonyl functional groups during AFP (activating fog period) and DFP (dissipating fog period), respectively, accompanied by acidic aerosol (having catalytic ability) and high aerosol liquid water content conditions was found to be significant. Whereas the fragmentation process was dominant along with functionalization of -RCOOH or carbonyl (aldehyde/ketone) and -RCOOH moieties during FP (fog period) and PoFP (post-fog period), respectively. Transition metals play an important role in aqueous production of secondary organic aerosol (SOA) especially during the night-time. Crustal sources had the highest scavenging efficiency along with WSOC playing an important role in nucleation scavenging. Fine droplets had a higher concentration of species with a larger fraction of highly oxidized organic matter (OM) as compared to coarse or medium size droplets. Also, a new approach to calculate absorption by black carbon (BC) and brown carbon (BrC) was proposed, which found the water-soluble brown carbon (WSBrC) absorption value in aerosol to be up to 1.8 times higher than that measured in their corresponding aqueous extracts. Organic aerosol plays a vital role in facilitating fog formation and is responsible for the longer residence time in the ambient atmosphere. Ammonia plays an important role in stabilizing organic aerosol and aids to this recurring haze-fog-haze cycle that is dominant during wintertime in the IGP. Therefore, controlling the major anthropogenic sources of organic aerosol and ammonia should be our top priority in this part of the world.

In-Depth Analysis of Physicochemical Properties of Particulate Matter (PM10, PM2.5 and PM1) and Its Characterization through FTIR, XRD and SEM–EDX Techniques in the Foothills of the Hindu Kush Region of Northern Pakistan

The current study investigates the variation and physicochemical properties of ambient particulate matter (PM) in the very important location which lies in the foothills of the Hindu Kush ranges in northern Pakistan. This work investigates the mass concentration, mineral content, elemental composition and morphology of PM in three size fractions, i.e., PM1, PM2.5 and PM10, during the year of 2019. The collected samples were characterized by microscopic and spectroscopic techniques like Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) spectroscopy. During the study period, the average temperature, relative humidity, rainfall and wind speed were found to be 17.9 °C, 65.83%, 73.75 mm and 0.23 m/s, respectively. The results showed that the 24 h average mass concentration of PM10, PM2.5 and PM1 were 64 µgm−3, 43.9 µgm−3 and 22.4 µgm−3, respectively. The 24 h concentration of both PM10 and PM2.5 were 1.42 and 2.92 times greater, respectively, than the WHO limits. This study confirms the presence of minerals such as wollastonite, ammonium sulphate, wustite, illite, kaolinite, augite, crocidolite, calcite, calcium aluminosilicate, hematite, copper sulphate, dolomite, quartz, vaterite, calcium iron oxide, muscovite, gypsum and vermiculite. On the basis of FESEM-EDX analysis, 14 elements (O, C, Al, Si, Mg, Na, K, Ca, Fe, N, Mo, B, S and Cl) and six groups of PM (carbonaceous (45%), sulfate (13%), bioaerosols (8%), aluminosilicates (19%), quartz (10%) and nitrate (3%)) were identified.

Particulate matter exposure in biomass-burning homes of different communities of Brahmaputra Valley

Biomass burning for cooking prevalent in the developing countries is an issue which has been a concern for the past several decades for the noxious emissions and subsequent effects on the health of women and children due to the exposure of particulate matter (PM) and other gases. In this study, PM (PM₁, PM_2.5, and PM₁₀) were measured in biomass-burning households for different communities of Brahmaputra Valley region northeast India by a 31-channel aerosol spectrometer. The levels of emission of PM in the case of different community households were found to be significantly different. Also, the emission characteristics of different cooking time of the day were found to be different across communities. The emission levels in the biomass-burning households were compared with emission in household using "clean" LPG fuel, and it was found that the biomass fuels emitted 10-12 times more PM_2.5 and 6-7 times more PM₁₀. The number densities of the emission were found to be more with smaller sizes of particulates which could explain why such biomass-burning emissions can pose with greater health risks. The exposure doses were calculated and were found to be about three times higher in biomass-burning houses than "clean" LPG fuel. It is important to note that the exposure from biomass burning while cooking has a gender perspective. The woman of the house generally takes care of the activities in the kitchen and get exposed to the noxious PM and the gases. Children often accompany their mothers and face the same fate.

Ambient ozone over mid-Brahmaputra Valley, India: effects of local emissions and atmospheric transport on the photostationary state

This study presents the characteristics of ground level atmospheric ozone (O₃) over the rural mid-Brahmaputra Valley region of the northeastern India. Ozone and oxides of nitrogen (NO_x = NO + NO₂) concentration data were obtained from continuous measurement of O₃ and NO_x housed at the MAPAN-AQM station at Tezpur University. The meteorological parameters were obtained from the same station. The diel, monthly, and seasonal variations of O₃ were studied. The O₃-NO_x photostationary state (PS) was carefully examined and it was found that the net O₃ concertation deviated substantially from the PS during the winter season. The deviation could be attributed to local biomass burning, biogenic VOC emission from forest and agriculture, and long-range transport of peroxyacyl nitrate (PAN). The long-range transport has been ascertained by examining the ventilation coefficients (VC), which correlated with the steep growth of net O₃ concentrations in the morning hours. The HYSPLIT air mass back trajectories were used in concentration-weighted trajectory (CWT) analyses of O₃ to assess the long-range regional transport of O₃ precursors, which positively influenced local O₃ concentrations.

Mass Concentration, Chemical Composition, and Source Characteristics of PM2.5 in a Plateau Slope City in Southwest China

In order to investigate the seasonal variations in the chemical characteristics of PM2.5 at the plateau slope of a mountain city in southwest China, 178 PM2.5 filters (89 quartz and 89 Teflon samples for PM2.5) were collected to sample the urban air of Wenshan in spring and autumn 2016 at three sites. The mass concentrations, water-soluble inorganic ions, organic and inorganic carbon concentrations, and inorganic elements constituting PM2.5 were determined, principal component analysis was used to identify potential sources of PM2.5, and the backward trajectory model was used to calculate the contribution of the long-distance transmission of air particles to the Wenshan area. The average concentration of PM2.5 in spring and autumn was 44.85 ± 10.99 μg/m3. Secondary inorganic aerosols contributed 21.82% and 16.50% of the total PM2.5 in spring and autumn, respectively. The daily mean value of OC/EC indicated that the measured SOC content was generated by the photochemical processes active during the sampling days. However, elements from anthropogenic sources (Ti, Si, Ca, Fe, Al, K, Mg, Na, Sb, Zn, P, Pb, Mn, As and Cu) accounted for 99.38% and 99.24% of the total inorganic elements in spring and autumn, respectively. Finally, source apportionment showed that SIA, dust, industry, biomass burning, motor vehicle emissions and copper smelting emissions constituted the major components in Wenshan. This study is the first to investigate the chemical characterizations and sources of PM2.5 in Wenshan, and it provides effective support for local governments formulating air pollution control policies.

Metals in coarse ambient aerosol as markers for source apportionment and their health risk assessment over an eastern coastal urban atmosphere in India

Ambient PM₁₀ (particulate matter with aerodynamic diameter ≤ 10 µm) samples were collected and characterized from July 2012 to August 2013 with the objective to evaluate the variation in elemental concentration and use the same as markers for source apportionment and health risk assessment for the first time over Bhubaneswar, India. The yearly average mass of PM₁₀ was 82.28 µg/m³, which was ~ 37% higher than the national ambient air quality (NAAQ) standards. Maximum PM₁₀ concentration was observed during winter season followed by post-monsoon, pre-monsoon, and monsoon months. Acid soluble components in the PM₁₀ samples were analyzed using ICP-OES (inductive coupled plasma optical emission spectroscopy), and 19 different elements including heavy metals were determined. Enrichment factor analysis attributed the source to either crustal or non-crustal origin. Principal component analysis (PCA) revealed that crustal sources, industrial activities, and vehicular emissions were significant contributors to PM mass. The contribution of total average elemental concentration showed a seasonal variation with the lowest (11.96 µg/m³) and highest (17.77 µg/m³) during monsoon and winter, respectively, which is relatively less significant than the variation in total PM₁₀ mass that ranged between 48.43 µg/m³ in monsoon and 138.24 µg/m³ during the winter season. This observation evidences the predominant contribution of local/regional emission sources to the metallic components in coarse PM₁₀ mass, which is corroborated by the wind pattern studies carried out using polar plots and a Lagrangian Particle Dispersion Model (LPDM) FLEXPART. Further, carcinogenic and non-carcinogenic health risk assessments of the measured elements that find their way into the human body through different exposure pathways have been calculated using United State Environmental Protection Agency (USEPA) standards. The carcinogenic risk of most of the elements was insignificant. The potential risk assessment study revealed that regular exposure to heavy metals through the ingestion pathway caused detrimental health effects. These effects were observed to be more severe in children in comparison to adults.

A review of the main strategies used in the interpretation of similar chemical profiles yielded by receptor models in the source apportionment of particulate matter

Receptor models have been widely used for the source apportionment of airborne particulate matter. However, in the last 10 years, the use of factor analysis-based models, such as PMF and UNMIX, has increased significantly. The results yielded by these models must be interpreted by users who must know all variables influencing the modeling, and without this knowledge, the probability of incorrect interpretation of the source profiles may increase, especially when two or more sources have similar chemical profiles. Concerning the quality of data, this work shows that a broad characterization of PM composition, including inorganic, organic, and mineralogical species can improve this process, avoiding misinterpretation and the attribution of mixed or unidentified sources. This work aims to provide readers with some answers for a question often risen during source apportionment studies: Which source markers should be used for better separation and interpretation of source profiles? This review shows there is no right answer for this because different strategies can be used for this purpose. Therefore, this review aims to compile and highlight qualitatively the key strategies already used by several experienced receptor models users, combining the use of inorganic, organic, and mineralogical markers of PM for better separation and interpretation of the profiles yielded by receptor models. Also, this work presents a compilation in tables of the main chemical species reported in the literature as markers for interpreting the source profiles.

Anatomical, physiological, and chemical alterations in lichen (Parmotrema tinctorum (Nyl.) Hale) transplants due to air pollution in two cities of Brahmaputra Valley, India

The lichen species Parmotrema tinctorum (Nyl.) Hale was transplanted in two cities-Tezpur (small) and Guwahati (large)-of the Brahmaputra Valley to assess the impact of air pollution on the anatomy and physiology, and accumulation of pollutants. Significant damage to the anatomy was observed in samples, and the degree of damage was found to be higher in the transplants of the larger city. In the lichen transplants from locations having high traffic density, the total chlorophyll content was found to fall; on the contrary, electrical conductivity was found to be higher. The exposed-to-control ratio showed severe accumulation of Cd in all the transplants. Elements such as Cd, Pb, and Zn were found to be enriched in all the lichen samples from both Guwahati as well as Tezpur city. Besides, Cr, Cu, K, and Ni were also realized to be enhanced to a moderate extent. The correlations of indicator metal species pairs showed that anthropogenic influence was quite clear.

Morphology and mineralogy of ambient particulate matter over mid-Brahmaputra Valley: application of SEM–EDX, XRD, and FTIR techniques

Ambient particulate matter (PM), collected during a dust event over mid-Brahmaputra Valley of India, was characterized. The PM samples were analyzed using scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) techniques. The SEM micrographs revealed varied shapes of the PM, viz. spherical, irregular, angular, cluster, flaky, rod-like, crystalline and agglomerate structures indicating the probable nature of their sources and formation as biogenic, geogenic, or anthropogenic. Some biogenic particles like plant materials, pollens, and diatoms were captured under SEM. The presence of diatom in PM samples was indicative of wind-blown dust from the dried bed of the Brahmaputra River. The honeycomb-like structures of brochosomes secreted by the leafhoppers of the Cicadellidae family were also captured. On the contrary, the background sample had mostly carbonaceous particles. The XRD and FTIR analyses indicated the presence of quartz, feldspar, kaolinite, illite, augite, and calcium aluminum silicate, cerussite, calcite, montmorllonite, and organic carbon. The airmass backward trajectory analysis explained the local contribution of the dust.

Emission factors of ultrafine particulate matter (PM<0.1 μm) and particle-bound polycyclic aromatic hydrocarbons from biomass combustion for source apportionment

Data for source apportionment estimation was obtained from combustion of 11 types of biomass (rubber wood, palm kernel, palm fiber, sugarcane bagasse, sugarcane leaves, maize residue, rice stubble, rice straw, Xylocarpus moluccensis, Avicennia alba Blume and Rhizophora mucronata) and bituminous coal. Combustion was carried out in a tube furnace and emitted particulate matter (PM) was collected using a nanosampler that segregated particle sizes down to 0.1 μm. Emission factors of PM < 0.1 μm were in the range of 0.11-0.28 g kg^-1 (∼1-8% of total PM), except in the case of Rhizophora mucronata, which had an emission factor of 0.071 ± 0.004 g kg^-1 (∼18% of total PM). The dominant polycyclic aromatic hydrocarbons (PAHs) found on PM < 0.1 μm were chrysene from combustion of rubber wood, palm kernel, palm fiber, maize residue, Xylocarpus moluccensis, Avicennia alba Blume, Rhizophora mucronata and bituminous coal; benzo[b]fluoranthene from combustion of rice straw, sugarcane bagasse and sugarcane leaves; and benzo[k]fluoranthene from rice stubble combustion. The emission factors of PAHs bound to PM < 0.1 μm from biomass combustion ranged from 0.005 to 0.044 mg kg^-1 and the emission factor from bituminous coal combustion was 0.1411 ± 0.0004 mg kg^-1. The carcinogenic potency equivalent or benzo[a]pyrene equivalent was highest from bituminous coal combustion (0.1252 mg kg^-1) and between 0.0019 and 0.0192 mg kg^-1 from biomass combustion. However, emission factors of both PM and particle-bound PAHs from biomass combustion were affected by moisture content of biomass and moisture contents of biomass used in this study were quite low, ranging from 0.165 to 0.863%.

Water-soluble ionic species in atmospheric aerosols over Dhauladhar region of North-Western Himalaya

Water-soluble ionic species (WSIS) have been used as potential markers for different source(s) and underlining process(es) emitting and transforming atmospheric aerosols. PM₁₀ aerosol sampling was performed once in a week for a complete one year, at a mid-altitude urban and a low-altitude rural location simultaneously in the Dhauladhar region of the North-Western Himalaya. Aerosol samples were analysed for major WSIS (anions: F^-, Cl^-, NO₃^-, PO₄^3- and SO₄^2-; cations: Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺) using the ion chromatography system. Results showed that WSIS constitutes around 15% of PM₁₀ aerosol load in the region. SO₄^2- contributes the maximum (~ 50%) followed by NO₃^- (~ 12.5%) and NH₄⁺ (~ 12.5%) to the total concentration of WSIS analysed. During all the seasons, average concentrations of PM₁₀ and associated WSIS were observed to be higher over the rural location in comparison to the urban location. The total concentration of WSIS was found to be maximum during the winter season. Principal component analysis performed on the WSIS concentration dataset revealed four major sources of PM₁₀-associated WSIS viz. re-suspension of soil or local sediments; conversion of pollutant gases (SO_x, NO_x and NH₃) to particles, i.e., secondary inorganic aerosol formation; evaporative loss or re-suspension of inorganic (NPK) fertilizers' residues and biomass/crop-residue burning emissions in the Dhauladhar region of the North-Western Himalaya.

Trace metals in indoor dust from a university campus in Northeast India: implication for health risk

This study reports concentrations of trace metals and the associated health risks in settled dust of different microenvironments of a university in Northeast India. Settled dust samples were collected from the most accessible indoor locations by the students of Tezpur University, a rural-residential university of mid Brahmaputra Valley of Assam. Collected samples were digested in an aqua regia-assisted microwave digestion system and analyzed for iron (Fe), nickel (Ni), zinc (Zn), cadmium (Cd), and lead (Pb) using atomic absorption spectroscopy (AAS). The highest concentration was obtained for Fe with a mean value of 1353.51 ± 123 mg/kg. Cadmium showed the lowest concentration with a mean value of 0.75 ± 0.57 mg/kg. Cadmium was the highly enriched element followed by Pb, Zn, and Ni. The metals mostly fall in the "extremely high enrichment" category. The study revealed that infiltrated soil or street dust, eroding wall paints, and automotive sources were the main contributing sources of the metals. The calculated Hazard Index (HI) value, 0.39, was lower than the acceptable HI value of 1 indicating no significant non-cancer risk to the students from exposure to these heavy metals at present. The study also found no carcinogenic risk on exposure to the metals present in the indoor dust samples.

Seasonal characteristics of aerosols (PM2.5 and PM10) and their source apportionment using PMF: A four year study over Delhi, India

The present study attempts to explore and compare the seasonal variability in chemical composition and contributions of different sources of fine and coarse fractions of aerosols (PM_2.5 and PM₁₀) in Delhi, India from January 2013 to December 2016. The annual average concentrations of PM_2.5 and PM₁₀ were 131 ± 79 μg m^-3 (range: 17-417 μg m^-3) and 238 ± 106 μg m^-3 (range: 34-537 μg m^-3), respectively. PM_2.5 and PM₁₀ samples were chemically characterized to assess their chemical components [i.e. organic carbon (OC), elemental carbon (EC), water soluble inorganic ionic components (WSICs) and heavy and trace elements] and then used for estimation of enrichment factors (EFs) and applied positive matrix factorization (PMF5) model to evaluate their prominent sources on seasonal basis in Delhi. PMF identified eight major sources i.e. Secondary nitrate (SN), secondary sulphate (SS), vehicular emissions (VE), biomass burning (BB), soil dust (SD), fossil fuel combustion (FFC), sodium and magnesium salts (SMS) and industrial emissions (IE). Total carbon contributes ∼28% to the total PM_2.5 concentration and 24% to the total PM₁₀ concentration and followed the similar seasonality pattern. SN and SS followed opposite seasonal pattern, where SN was higher during colder seasons while SS was greater during warm seasons. The seasonal differences in VE contributions were not very striking as it prevails evidently most of year. Emissions from BB is one of the major sources in Delhi with larger contribution during winter and post monsoon seasons due to stable meteorological conditions and aggrandized biomass burning (agriculture residue burning in and around the regions; mainly Punjab and Haryana) and domestic heating during the season. Conditional Bivariate Probability Function (CBPF) plots revealed that the maximum concentrations of PM_2.5 and PM₁₀ were carried by north westerly winds (north-western Indo Gangetic Plains of India).

Seasonal concentration distribution of PM1.0 and PM2.5 and a risk assessment of bound trace metals in Harbin, China: Effect of the species distribution of heavy metals and heat supply

To clarify the potential carcinogenic/noncarcinogenic risk posed by particulate matter (PM) in Harbin, a city in China with the typical heat supply, the concentrations of PM_1.0 and PM_2.5 were analyzed from Nov. 2014 to Nov. 2015, and the compositions of heavy metals and water-soluble ions (WSIs) were determined. The continuous heat supply from October to April led to serious air pollution in Harbin, thus leading to a significant increase in particle numbers (especially for PM_1.0). Specifically, coal combustion under heat supply conditions led to significant emissions of PM_1.0 and PM_2.5, especially heavy metals and secondary atmospheric pollutants, including SO₄^2-, NO₃^-, and NH₄⁺. Natural occurrences such as dust storms in April and May, as well as straw combustion in October, also contributed to the increase in WSIs and heavy metals. The exposure risk assessment results demonstrated that Zn was the main contributor to the average daily dose through ingestion and inhalation, ADD_Ing and ADD_inh, respectively, among the 8 heavy metals, accounting for 51.7-52.5% of the ADD_Ing values and 52.5% of the ADD_inh values. The contribution of Zn was followed by those of Pb, Cr, Cu and Mn, while those of Ni, Cd, and Co were quite low (<2.2%).

Soil PAHs against varied land use of a small city (Tezpur) of middle Brahmaputra Valley: seasonality, sources, and long-range transport

This study reports soil PAHs from a small city (Tezpur) of the mid-Brahmaputra Valley. The soil PAHs has been assessed from representative land use using detailed protocol of extracting, cleaning, and quantitative analysis by HPLC technique. The concentrations of PAHs showed minimum spatial variability and yet showed strong seasonal variability, which could be typical of small cities having weak local source strengths. On examining the air mass reaching the region, it appeared that there has been explicit effect of long-range transport. The HYSPLIT back trajectories reaching the study area during different seasons showed variations in terms of their origins and transport pathways. This might have led to differential long-range transport of PAHs, which is reflected in the seasonal variabilities of the concentrations of PAHs. The seasonal variations were much profound with the highest ΣPAHs concentration during post-monsoon (7961 ng g^-1) followed by pre-monsoon (2414 ng g^-1) and monsoon (773 ng g^-1) season. The toxicity of the PAHs was examined as BaP equivalent (BaPeq) concentrations, which were found to be on the lower side as compared to the studies conducted elsewhere. The percentage contribution of 3- and 4-ring compounds was found to be greater. An attempt also was made to apportion the sources of the PAHs by application of diagnostic ratios, principal component analysis-multiple linear regression (PCA-MLR) and hierarchal cluster analysis (HCA), which revealed that coal and biomass burning and vehicular emissions are the major contributors to the PAHs load in Tezpur city.

Biomonitoring by epiphytic lichen species-Pyxine cocoes (Sw.) Nyl.: understanding characteristics of trace metal in ambient air of different landuses in mid-Brahmaputra Valley

This study presents a comparative assessment of the trace metal air pollutants of urban, peri-urban, and rural areas of the Brahmaputra Valley plain in the Eastern Himalayan region using biomonitoring of Pyxine cocoes. In situ collection of the thalli growing on Bombax sp. from representative locations was done, which was analyzed for Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn using ICP-OES. The metals, viz. Cd, Cr, Ni, Pb, and Zn, were highly enriched, indicating anthropogenic influences. The coefficients of variation (CV) of Co, Cr, and Ni were also high, pointing at their accumulation from local sources. Influence of local sources was also observed for Cd, Fe, and Mn in peri-urban and Cd in urban samples. Metals related to automobiles were accumulated in greater volume in samples of peri-urban locations, which implies the impact of the highway that runs through these locations and other associated human activities. The samples of urban areas were found to be enriched with metals originating from both vehicular emissions and road dust. Also, accumulations of Co, Cr, Cu, Fe, Mn, and Ni in the lichen thalli were found to be around tea gardens. Inter-species correlations were found to be positively significant for most of the elements. Principal component analysis (PCA) of the metal data revealed that vehicular emission and coal burning, street dust, and crustal dust were the major sources of trace metals in the ambient air of the region.

Modeling and efficient quantified risk assessment of haze causation system in China related to vehicle emissions with uncertainty consideration

Urban haze has become a severe pollution problem in China. Vehicle emission may be a key factor leading to haze pollution in China's megacities due to the rapid growth of vehicles and corresponding energy consumption. Until now, the haze formation mechanisms in China remain highly uncertain, which have not yet been understood quantitatively. In this work, an efficient modified haze causation system related to vehicle emissions is developed for reliable quantified risk assessment of urban haze in China's megacities. And fuzzy mathematical theory combining with fault tree approach is investigated and employed as the analysis tool/strategy. To provide objective basis for the reliability and practicability of the quantitative assessment results, an efficient data extraction strategy and relevant mathematical models are proposed and developed for the probability determination of basic risk events. Besides, the probability uncertainty of basic risk events during the data extraction is taken into account, where the occurrence probability of basic events is described as triangular fuzzy number, the quantitative analysis results will be more reliable and more tally with the actual situation. After the haze causation system related to vehicle emissions is established along with the identification of all critical risk factors related to vehicle emissions, Beijing and Tianjin are taken as illustrated case studies for the quantified risk assessment of haze causation system related to vehicle emissions in China. All the analysis results demonstrated that this work may provide a useful and effective tool/strategy for efficient quantified risk assessment and risk management of haze causation system relate to vehicle emission in China.

Chemical composition and source apportionment of PM1 and PM2.5 in a national coal chemical industrial base of the Golden Energy Triangle, Northwest China

As part of the Energy Golden Triangle in northwest China and the largest coal-to-liquids industry in the world, the emission and contamination of fine particles in the Ningdong National Energy and Chemical Industrial Base (NECIB) are unknown. There are also large knowledge gaps in the association of air pollution with coal-to-liquids industry. This paper reports the chemical composition and source apportionment of PM₁ and PM_2.5 collected at two industrial sites Yinglite (YLT) and Baofeng (BF) from a field campaign during summer 2016 and winter 2017. Major chemical components in PM₁ and PM_2.5, including carbonaceous aerosols, water-soluble inorganic ions, and metal elements were analyzed. The Positive Matrix Factorization (PMF) model and the ISORROPIA II thermodynamic equilibrium model were used to track possible sources and contributions of these chemical components to the formation of the two fine particles. The results identified four primary sources of the fine particles, including vehicle emissions, biomass burning and waste incineration, the secondary aerosols and coal combustion, and soil dust. The PM₁ and PM_2.5 concentrations were higher in winter than summer. The summed secondary inorganic and carbonaceous aerosols accounted for 36.1-40.0% of PM_2.5 mass. The total mass of chemical components identified in the source apportionment only explained about 64.2 to 72.4% of the PM_2.5 mass. These results imply some missing sources in this large-scale coal chemical industry base. A coupled weather forecasting and atmospheric chemistry model WRF-Chem was employed to simulate the PM_2.5 mass and concentrations of OC and EC, and to examine the origins of PM_2.5 across the NECIB. The modeled concentrations of OC and EC were consistent with the sampled data, but the modeled mass of PM_2.5 is lower considerably than the measurements, again suggesting unknown sources of fine particles in this energy industrial base.

Contribution of meteorological factors to particulate pollution during winters in Beijing

Associated with its modernization, Beijing has experienced significant fine particulate matter (PM_2.5) pollution, especially in winter. In 2016, severe PM_2.5 pollution (PM_2.5 > 250 μg/m³) lasted over 6 days and affected over 23 million people. A major challenge in dealing with this issue is the uncertainty regarding the influence of individual meteorological factors to the overall PM_2.5 concentration in Beijing. Thus, applying an empirical regression method to long-term ground-based PM_2.5 data and meteorological sounding measurements, we attempted to analyze the influence of individual meteorological factors on PM_2.5 pollution during winters in Beijing. We found that horizontal dilution and vertical aggregation plays a major role in PM_2.5 pollution during the winter of 2016. The impact of horizontal wind on PM_2.5 concentration in Beijing was mainly from its dilution, the dilution of northerly wind contributed 27.8% in 2016, far below its contribution in 2015 (32.2%). The contribution from the growing vertical aggregation observed in 2016 was mainly the result of both the lower height of the planetary boundary layer and the greater depth of the temperature inversion. The dilution of the planetary boundary layer height contributed 9.8% to PM_2.5 pollution in 2016, 5.4% lower than that in 2017. Compared with the temperature difference of the inversion layer, the temperature inversion depth better reflects the aggregated impact of temperature inversions to PM_2.5, which was 10.9% in 2015, and the ratio rose to 14.3% in 2016. Relative humidity is also an important impacting factor, which contributed 41.0%, far higher than the ratio in 2017 (26.7%). Such results imply that we should focus on not only local emission control, but also horizontal atmospheric transport and meteorological conditions in order to provide a more accurate analysis of pollution mechanisms, conductive to air pollution governance in Beijing.

An advanced three-way factor analysis model (SDABB model) for size-resolved PM source apportionment constrained by size distribution of chemical species in source profiles

Source samples including crustal dust, cement dust, coal combustion were sampled and ambient samples of PM_2.5 and PM₁₀ were synchronously collected in Hefei from April to December 2014. The size distributions of the markers in the measured source profiles were incorporated into ME-2 solution to develop a new method, called the SDABB model (an advanced ABB three-way factor analysis model incorporating size distribution information). The performance of this model was investigated using three-way synthetic and ambient dataset. For the synthetic tests, the size distributions of markers estimated by the SDABB model were more consistent with true condition. The AAEs between estimated and observed contributions of the SDABB ranged from 15.2% to 29.0% for PM₁₀ and 19.9%-31.6% for PM_2.5, which is lower than those of PMF2. For the ambient PM, six source categories were identified by SDABB for both sizes, although the profiles were different. The source contributions were sulphate (33.33% and 24.53%), nitrate and SOC (22.33% and 18.16%), coal combustion (19.01% and 18.23%), vehicular exhaust (12.99% and 12.07%), crustal dust (10.69% and 19.40%) and cement dust (1.65% and 5.39%) for PM_2.5 and PM₁₀ respectively. In addition, the estimated ratios of Al, Si, Ti and Fe in CRD were 0.76, 0.84, 1.10 and 0.85; those of Al and Si in CC were 0.42 and 0.66; Ca and Si in CD were 0.95 and 1.10; NO₃^- and NH₄⁺ in nitrate were 1.11 and 1.01; and SO₄^2- and NH₄⁺ in sulphate were 0.96 and 1.16. These modeled ratios were consistent with the measured ratios. The size distribution of contributions also came close to reality. Thus, the advanced SDABB three-way model can better capture the characteristics of sources between sizes by effectively incorporating the size distributions of the markers as physical constraints.