Available via license: CC BY 4.0
Content may be subject to copyright.
A preview of the PDF is not available
Size-resolved Composition and Morphology of Particulate Matter During the Southwest Monsoon in Metro Manila, Philippines
Abstract
This paper presents novel results from size-resolved particulate matter (PM) mass, composition, and morphology measurements conducted during the 2018 Southwest Monsoon (SWM) season in Metro Manila, Philippines. Micro-Orifice Uniform Deposit Impactors (MOUDIs) were used to collect PM sample sets that were analyzed for mass, morphology, black carbon (BC), and composition of the water-soluble fraction. The bulk of the PM mass was between 0.18–1.0 µm with a dominant mode between 0.32–0.56 µm. Similarly, most of the black carbon (BC) mass was found between 0.10–1.0 µm (the so-called Greenfield gap), peaking between 0.18–0.32 µm, where wet scavenging by rain is inefficient. In the range of 0.10–0.18 µm, BC constituted 78.1 % of the measured mass. Comparable contributions of BC (26.9 %) and the water-soluble fraction (31.3 %) to total PM were observed and most of the unresolved mass, which in total amounted to 41.8 %, was for diameters exceeding 0.32 µm. The water-soluble ions and elements exhibited an average combined concentration of 8.53 µg m−3, with SO42−, NH4⁺, NO3−, Na⁺, and Cl− as the major contributors. Positive Matrix Factorization (PMF) was applied to identify the possible aerosol sources and estimate their contribution to the water-soluble fraction of collected PM. The factor with the highest contribution was attributed to Aged/Transported aerosol (48.0 %) while Sea Salt (22.5 %) and “Combustion” emissions (18.7 %) had comparable contributions. Vehicular/Resuspended Dust (5.6 %) as well as Waste Processing emissions (5.1 %) were also identified. Microscopy analysis highlighted the ubiquity of non-spherical particles regardless of size, which is significant when considering calculations of parameters such as single scattering albedo, asymmetry parameter, and extinction efficiency.
Results of this work have implications for aerosol impacts on public health, visibility, and regional climate as each of these depend on physicochemical properties of particles as a function of size. The significant influence from Aged/Transported aerosol to Metro Manila during the SWM season indicates that local sources in this megacity do not fully govern this coastal area's aerosol properties and that PM in Southeast Asia can travel long distances regardless of the significant precipitation and potential wet scavenging that could occur. That the majority of the regional aerosol mass burden is accounted for by BC and other insoluble components has important downstream effects on the aerosol hygroscopic properties, which depend on composition. The results are relevant for understanding the impacts of monsoonal features on size-resolved aerosol properties, notably aqueous processing and wet scavenging. Finally, the results of this work provide contextual data for future sampling campaigns in Southeast Asia such as the airborne component of the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex) planned for the SWM season in 2019. Aerosol characterization via remote-sensing is notoriously difficult in Southeast Asia, which elevates the importance of datasets such as the one presented here.
... Metro Manila is the capital of the Philippines and the country's largest megacity, hosting the majority of economic activity and a population of ~12.88 million (Authority, 2015). Precipitation was sampled from February 2007 to December 2016 at the Manila Observatory (87 m ASL) on the Ateneo de Manila University campus in Quezon City, which is characterized by pollutants of varying types from multiple sources, such as biomass burning, vehicles, and industry (Alas et al., 2018;Braun et al., 2020;Cohen et al., 2009;Cruz et al., 2019;Kecorius et al., 2017). The Southwest Monsoon season (May-October) is associated with southwesterly flow, more rain, and extensive biomass burning upwind of Luzon over the Maritime Continent (Cayanan et al., 2011;Cruz et al., 2013;Hilario et al., 2020b;Reid et al., 2013;Villafuerte et al., 2014;Xian et al., 2013). ...
... The Southwest Monsoon season (May-October) is associated with southwesterly flow, more rain, and extensive biomass burning upwind of Luzon over the Maritime Continent (Cayanan et al., 2011;Cruz et al., 2013;Hilario et al., 2020b;Reid et al., 2013;Villafuerte et al., 2014;Xian et al., 2013). Cruz et al. (2019) showed with size-resolved aerosol measurements and positive matrix factorization modeling that five predominant pollution sources during the Southwest Monsoon include aged aerosol, sea salt, combustion, waste processing, and vehicular/resuspended dust. The period of time between November and April coincides with a dry season with more northeasterly winds (Bagtasa et al., 2018;Chang et al., 2005;Cruz et al., 2013;Moron et al., 2009), including influence from both East Asia and local burning Table 1 Geographic details associated with the nine study sites and the date range of data used in this work. ...
... An outlier point was removed at WA14 for 11-August 18, 2015 and at FL11 for 13-April 19, 2016. diversity of regional sources and the wide range of meteorological conditions it experiences including shifts in predominant wind directions in different seasons Cruz et al., 2019). More broadly, two of the three island sites (HI00 and MM) exhibited the most monthly variability in pH as compared to the continental sites. ...
This study examined spatial variations of precipitation accumulation and chemistry for six sites located on the West and East Coasts of the U.S., and one site each on the islands of Hawaii, Bermuda, and Luzon of the Philippines (specifically Manila). The nine coastal sites ranged widely in both mean annual precipitation accumulation, ranging from 40 cm (Mauna Loa, Hawaii) to 275 cm (Washington), and in terms of monthly profiles. The three island sites represented the extremes of differences in terms of chemical profiles, with Bermuda having the highest overall ion concentrations driven mainly by sea salt, Hawaii having the highest SO4²⁻ mass fractions due to the nearby influence of volcanic SO2 emissions and mid-tropospheric transport of anthropogenic pollution, and Manila exhibiting the highest concentration of non-marine ions (NH4⁺, non-sea salt [nss] SO4²⁻, nss Ca²⁺, NO3⁻, nss K⁺, nss Na⁺, nss Mg²⁺) linked to anthropogenic, biomass burning, and crustal emissions. The Manila site exhibited the most variability in composition throughout the year due to shifting wind directions and having diverse regional and local pollutant sources. In contrast to the three island sites, the North American continental sites exhibited less variability in precipitation composition with sea salt being the most abundant constituent followed by some combination of SO4²⁻, NO3⁻, and NH4⁺. The mean-annual pH values ranged from 4.88 (South Carolina) to 5.40 (central California) with NH4⁺ exhibiting the highest neutralization factors for all sites except Bermuda where dust tracer species (nss Ca²⁺) exhibited enhanced values. The results of this study highlight the sensitivity of wet deposition chemistry to regional considerations, elevation, time of year, and atmospheric circulations.
... The site was segregated from surrounding urban areas, including a major roadway, by a grove of trees circling the campus. However, it was clearly impacted by local urban emissions and long-range transport based on results from the first six months of data collected [16][17][18] . Sampling took place on the 3 rd floor of the MO office building, which was approximately 85 m above sea level. ...
... Additional MOUDI sets were collected on aluminum substrates for microscopy analysis using a Scanning Electron Microscope (SEM); however, these sets are not included in the dataset presented here. For more information on these sets, please refer to Cruz et al. 16 . ...
... A few papers have been produced using portions of this dataset already. Cruz et al. 16 looked at size-resolved PM composition during the 2018 southwest monsoon season and conducted positive matrix factorization (PMF) to identify PM sources, which were attributed to aged PM, sea salt, combustion emissions, vehicular/resuspended dust, and waste processing emissions. Braun et al. 18 presented case examples of long-range transport of PM from east and southeast Asia, such as biomass burning from the Maritime Continent and transport from continental East Asia. ...
Size-resolved aerosol samples were collected in Metro Manila between July 2018 and October 2019. Two Micro-Orifice Uniform Deposit Impactors (MOUDI) were deployed at Manila Observatory in Quezon City, Metro Manila with samples collected on a weekly basis for water-soluble speciation and mass quantification. Additional sets were collected for gravimetric and black carbon analysis, including during special events such as holidays. The unique aspect of the presented data is a year-long record with weekly frequency of size-resolved aerosol composition in a highly populated megacity where there is a lack of measurements. The data are suitable for research to understand the sources, evolution, and fate of atmospheric aerosols, as well as studies focusing on phenomena such as aerosol-cloud-precipitation-meteorology interactions, regional climate, boundary layer processes, and health effects. The dataset can be used to initialize, validate, and/or improve models and remote sensing algorithms.
... Also, due to increased levels of PM 10 during dust storms, their penetration into the depth of the human lungs exacerbates health conditions (Khaniabadi et al., 2017;Meng and Zhang, 2007). Human activities are high in urban environments, consequently leading to emissions of heavy metals that can contaminate dust (Cruz et al., 2019;Karri et al., 2016). Past work reported that in at least one urban environment, approximately 40% of PM can be attributed to the use of fossil fuels (Goudarzi et al., 2019;Parvizimehr et al., 2020). ...
Epidemiological studies have reported an association between air pollution and central nervous system disorders. However, its biological mechanisms are poorly understood. This study aimed to determine the effect of short-term environmental exposure to PM10 and associated heavy metals on changes in blood and urinary nervous markers in dusty conditions. A total of 44 healthy non-smokers were identified with a mean age of 36 years. Blood and urine samples were taken from these people 24 h before and after the dust storm to measure the biomarkers of the central nervous system. Cortisol, white blood cells (WBCs), neuron-specific enolase (NSE), and S100β were measured as blood markers, while vanillylmandelic acid (VMA) and homovanillic acid (HVA) were tracked as urine markers. These people had 7 h of environmental exposure in dusty conditions. Eleven heavy metals (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Co, Pb, and Zn) associated with PM10 were measured. The average PM10 concentration on dust days was 3.25 times higher than on normal days (309.81 μg m⁻³ vs. 86.11 μg m⁻³). The results of the statistical paired T-test showed that the mean S100β from pre-exposure to post-exposure increased by 5.85 ng L⁻¹ (P ≤ 0.004). The NSE mean of the pre-exposure (3.37 ± 3.48 μg L⁻¹) was significantly different from the NSE mean after exposure)4.15 ± 3.74 μg L⁻¹ ((P = 0.002). The post-exposure WBC mean was 0.59 times higher than that before exposure, albeit not statistically significant (P = 0.269). The mean VMA after exposure increased by 0.55 mg g⁻¹ CRT (Creatinine) compared to that before exposure. This difference was statistically significant (P = 0.000). Changes in S100β after exposure to dust storms had a high correlation with changes in Cr, Pb, and Fe metal concentrations, respectively (r = 0.81, r = 0.72, r = 0. 65). NSE changes were significantly associated with changes in Mn, Cd, and Fe (r = 0.71, r = 0.99, r = 0.71). Heavy metals associated with PM10 can damage neurons and astrocytes, promoting neuropsychiatric disorders in people with exposure.
... The main method that Gu HMs primarily originated from natural sources, anthropogenic and natural sources, and anthropogenic sources, respectively. Similar categories of sources were also identified in previous work in urban areas of Guangzhou (China) [79,80], urban areas of the desert southwest of the United States [81] inland [82] and coastal [83,84] arts of California, and Manila of the Philippines [85]. More detailed information about the loading of HMs on VARIMAX-rotated factors and the Scree plot of components number versus eigenvalue is provided in the supporting information (Table S1 and Fig. S1). ...
This study investigated the concentrations of suspended particulate matter £ 10 µm in diameter (PM10) and their heavy metal content, including cadmium, lead, chromium, zinc, nickel, aluminum, and iron, in ambient air in the Middle East: Shiraz, Iran. The Crystal Ball 7.3 software package was used to assess carcinogenic and non-carcinogenic health effects due to heavy metal exposure. The mean concentrations of heavy metals increased in the following order: Fe > Al > Zn > Pb > Cr > Ni > Cd. Meanwhile, the average concentrations of PM10 decreased during the same time frame. When comparing PM10 on various days of the week in Iran, including holidays (Thursday and Friday), two days after holidays (Saturday and Sunday), and other days (Monday, Tuesday and Wednesday), the concentrations were higher two days after the holidays as compared to other days of the week (p < 0.05). The excess lifetime cancer risk (ELCR) for Cr, especially for children was 1.20 × 10⁻², which surpassed suggested EPA levels. The non-carcinogenic values of heavy metals for children were significantly higher than those for adults for three pathways. The results indicate that children usually had more exposure to heavy metals associated with PM10 as compared to adults.
Lake Urmia, NW Iran, and S Caucasus region, has lost approximately three‐fourth of its water volume resulting in increased exposure of lacustrine deposits. Therefore, the role of Lake Urmia desiccated saline lands on local aerosols and rainwater compositions is still vague. This study investigates the temporal and seasonal patterns of rainwater chemistry from January 2018 to June 2018 (six months) in 13 stations throughout the Lake Urmia basin. The samples collected were analyzed using triple quadrupole inductively coupled plasma mass spectrometry (ICP‐QQQ) and ion chromatography (IC) to measure elemental and ionic concentrations. Then, the Hybrid Single‐Particle Lagrangian Integrated Trajectory model (HYSPLIT) was applied to identify the pathway and contribution of emissions. The results depict that the concentration of elemental and ionic components over different parts of the Lake Urmia basin are significantly different. West and north directions have the highest concentrations of marine ions associated with fewer toxic elements. In contrast, the east and south directions show a high concentration of heavy metal elements and ions. The high level of heavy and toxic elements at the east and south directions indicates that local anthropogenic sources are more influential. The seasonal and monthly variabilities of chemical compositions depict that the highest concentration of Na⁺, Mg²⁺, Ca²⁺, K⁺, Cl⁻, Br⁻, NO3⁻, Al, Cr, Mn, Fe, and Co were in the spring season and SO4²⁻, NH4⁺ and NO2⁻ were highest in winter. Seasonal variation for MSA, organic acids (i.e., Pyruvate, Adipate, and Oxalate), Ni, Cu, Zn, V, and Ti were not apparent. Cluster‐mean HYSPLIT backward trajectories results show the most dominant air mass sectors are from W (a: Iraq, Syria, and Arabian deserts; b: Mediterranean Sea; and c: KSA) and NE (the Caspian Sea and its vicinity), contributed to almost 65% and 22%, respectively. These air masses bring a significant quantity of crustal and marine aerosols, respectively. It is inferred that the Lake Urmia dried‐up lakebeds have less impact on the contribution of emissions across the region.
Monitoring and modeling aerosol particle lifecycle in Southeast Asia (SEA) is challenged by high cloud cover, complex meteorology, and the wide range of aerosol species, sources, and transformations found throughout the region. Satellite observations are limited, and there are few in situ observations of aerosol extinction profiles, aerosol properties, and environmental conditions. Therefore, accurate aerosol model outputs are crucial for the region. This work evaluates the Navy Aerosol Analysis and Prediction System Reanalysis (NAAPS-RA) aerosol optical thickness (AOT) and light extinction products using airborne aerosol and meteorological measurements from the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex) in SEA. Modeled AOTs and extinction coefficients were compared to those retrieved with a High Spectral Resolution Lidar (HSRL-2). Correlations were highest for AOT in the mixed layer (AOTML; R2 = 0.83, bias = 0.00, root mean square error [RMSE] = 0.03) compared to total AOT (R2 = 0.68, bias = 0.01, RMSE = 0.14), although the correlations between the observations and 1° × 1° degree NAAPS-RA outputs were weaker in regions with strong gradients in aerosol properties, such as near areas of active convection. Correlations between simulated and retrieved aerosol extinction coefficients were highest from 145–500 m (R2 = 0.75, bias = 0.01 km−1, RMSE = 0.08 km−1) and decreased with increasing altitude (R2 = 0.69 and 0.26, bias = 0.00 and 0.00 km−1, RMSE = 0.09 and 0.00 km−1 for 500–1500 m and > 1500 m, respectively), which was likely a result of the use of bulk cloud mixing parameterizations. We also investigated the role of possible relative humidity (RH) errors in extinction simulations. Despite negative biases in modeled RH (−4.9, −7.7, and −2.3 % for altitudes 1500 m, respectively), AOT and extinction agreement with the HSRL-2 did not change significantly at any altitude when RHs from dropsondes were substituted into the model. Improvements may have been stunted due to errors in how NAAPS-RA modeled physics of particle hygroscopic growth, dry particle mass concentrations, and/or dry mass extinction efficiencies, especially when combined with AOT corrections from data assimilation. Specifically, the model overestimated the hygroscopicity of (i) smoke particles from biomass burning in the Maritime Continent (MC), and (ii) anthropogenic emissions transported from East Asia. This work provides insight into how certain environmental and microphysical properties influence AOT and extinction simulations, which can then be interpreted in the context of modeling global concentrations of particle mass and cloud condensation nuclei (CCN).
Plain Language Summary
The extent of atmospheric chemical processing remains an uncertain aspect of air mass characterization. Addressing this uncertainty is important because chemical reactions in the atmosphere in the presence of water (aqueous processing) produce a large fraction of global aerosol mass. The oxalate‐to‐sulfate ratio has been proposed as an indicator of aqueous processing, where higher values point to increased processing of an air mass. In this study, we quantify a range in the oxalate‐to‐sulfate mass ratio (0.0154–0.0296) using data from multiple field campaigns encompassing a diverse set of environments. This range is robust near the surface for particles below 1 micrometer in diameter. Larger particles, especially dust, and biomass burning particles significantly affect the oxalate‐to‐sulfate ratio and thus may confound the interpretation of a high oxalate‐to‐sulfate ratio as a signal of aqueous processing. In the absence of dust and biomass burning particles, the oxalate‐to‐sulfate ratio range may be used to compare the relative extent of aqueous processing between different air masses.
The evaluation of black carbon (BC) sources is very important, especially in environmental sciences. This study shows how the contributions of biomass burning and fossil fuel/traffic to PM2.5 mass can be assessed. MABI was used for this purpose and gave the possibility to measure the transmission of light at different wavelengths. Absorption coefficients were calculated from measurements data and recalculated for concentrations of eBC. The samples of PM2.5 fraction were collected from February 1, 2020 to March 27, 2021 every third day in Krakow, Poland (50°04' N, 19°54'47" E). The concentrations of equivalent BC (eBC) from fossil fuel/traffic and biomass burning were in the range 0.82–11.64 μg m−3) and 0.007–0.84 μg m−3, respectively. At the same time, PM2.5 concentrations varied from 3.14 to 55.24 μg m−3. It means that about 18 % of PM2.5 mass belongs to eBC and 11.3 % of this value comes from biomass burning. The eBC contribution is the significant part of PM2.5 mass and we observed seasonal variation of the eBC concentration during the year with the peak in winter. The contribution of biomass burning to PM2.5 mass is more stable during the whole year. The eBC concentration during workdays is a bit higher than during weekend days but biomass burning is similar for both days (work and weekend taken as the mean for the whole period).
Fireworks degrade air quality, reduce visibility, alter atmospheric chemistry, and cause short-term adverse health effects. However, there have not been any comprehensive physicochemical and optical measurements of fireworks and their associated impacts in a Southeast Asia megacity, where fireworks are a regular part of the culture. Size-resolved particulate matter (PM) measurements were made before, during, and after New Year 2019 at the Manila Observatory in Quezon City, Philippines, as part of the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex). A High Spectral Resolution Lidar (HSRL) recorded a substantial increase in backscattered signal associated with high aerosol loading ~440 m above the surface during the peak of firework activities around 00:00 (local time). This was accompanied by PM2.5 concentrations peaking at 383.9 μg m−3. During the firework event, water-soluble ions and elements, which affect particle formation, growth, and fate, were mostly in the submicrometer diameter range. Total (> 0.056 µm) water-soluble bulk particle mass concentrations were enriched by 5.7 times during the fireworks relative to the background (i.e., average of before and after the firework). The water-soluble mass fraction of PM2.5 increased by 18.5 % above that of background values. Bulk particle hygroscopicity, kappa (κ), increased from 0.11 (background) to 0.18 (fireworks). Potassium and non-sea salt (nss) SO42− contributed the most (70.9 %) to the water-soluble mass, with their mass size distributions shifting from a smaller to a larger submicrometer mode during the firework event. On the other hand, mass size distributions for NO3−, Cl−, and Mg2+ (21.1 % mass contribution) shifted from a supermicrometer mode to a submicrometer mode. Being both uninfluenced by secondary aerosol formation and constituents of firework materials, a subset of species were identified as the best firework tracer species (Cu, Ba, Sr, K+, Al, and Pb). Although these species (excluding K+) only contributed 2.1 % of the total mass concentration of water-soluble ions and elements, they exhibited the highest enrichments (6.1 to 65.2) during the fireworks. Surface microscopy analysis confirmed the presence of potassium/chloride-rich cubic particles along with capsule-shaped particles in firework samples. The results of this study highlight how firework emissions change the physicochemical and optical properties of water-soluble particles (e.g., mass size distribution, composition, hygroscopicity, and aerosol backscatter), which subsequently alters the background aerosol's respirability, influence on surroundings, ability to uptake gases, and viability as cloud condensation nuclei (CCN).
We present the first study of the weekly cycles (WCs) of chemically speciated and size‐resolved particulate matter (PM) in Metro Manila, Philippines, a coastal megacity located within a highly complex meteorological environment that is subject to both anthropogenic and natural sources. To measure PM, Micro‐Orifice Uniform Deposit Impactors (MOUDIs) were deployed in Metro Manila from August 2018 to October 2019 and samples were analyzed for ionic and elemental species, including black carbon (BC). The WC in Metro Manila varied remarkably across seasons, linked to shifts in meteorology, transport, and aerosol source. Identified aerosol sources were traffic, local and regional burning, dust, sea salt, and secondary aerosol formation. Direct emissions induced a late workweek peak, while secondary aerosol formation led to a weekend peak in response to precursor buildup mainly from traffic. Seasonal analysis revealed that local burning from solid waste management and agricultural fires induced a strong WC peak while regional burning emissions from the Maritime Continent (MC) and possibly the Asian continent elevated seasonal baseline concentrations of the WC. BC showed a seasonally persistent WC, consistent in magnitude, weekly peak timing, and particle size. The dominant submicrometer WC and the contribution of BC across seasons have important ramifications on public health and policymaking, which are also discussed. As many of the observed WC patterns are undetectable when using only bulk PM, this study demonstrates that a seasonal, size‐resolved, and chemically speciated characterization is required to more fully understand the driving mechanisms governing WCs.
Air quality on the east coast of Peninsular Malaysia is influenced by local anthropogenic and biogenic emissions as well as marine air masses from the South China Sea and aged emissions transported from highly polluted East Asian regions during the winter monsoon season. An atmospheric observation tower has been constructed on this coastline at the Bachok Marine Research Station. Daily PM2.5 samples were collected from the top of the observation tower over a 3-week period, and ion chromatography was used to make time-resolved measurements of major atmospheric ions present in aerosol. SO42- was found to be the most dominant ion present and on average made up 66 % of the total ion content. Predictions of aerosol pH were made using the ISORROPIA II thermodynamic model, and it was estimated that the aerosol was highly acidic, with pH values ranging from -0.97 to 1.12. A clear difference in aerosol composition was found between continental air masses originating from industrialised regions of East Asia and marine air masses predominantly influenced by the South China Sea. For example, elevated SO42- concentrations and increased Cl- depletion were observed when continental air masses that had passed over highly industrialised regions of East Asia arrived at the measurement site. Correlation analyses of the ionic species and assessment of ratios between different ions provided an insight into common sources and formation pathways of key atmospheric ions, such as SO42-, NH4+ and C2O42-. To our knowledge, time-resolved measurements of water-soluble ions in PM2.5 are virtually non-existent in rural locations on the east coast of Peninsular Malaysia. Overall this dataset contributes towards a better understanding of atmospheric composition in the Maritime Continent, a region of the tropics that is vulnerable to the effects of poor air quality, largely as a result of rapid industrialisation in East Asia.
We studied the effect of aerosols inorganic chemical composition on the aerosol hygroscopicity of urban pollution in Brazil, where biofuels have been used in large scale. We applied size segregated inorganic chemical composition analysis using ISORROPIA II model and κ-Köhler theory to determine the hygroscopicity parameter (κ) of submicrometer aerosols measured in São Paulo city. The size dependence of organic and black carbon (BC) mass were estimated by chemical mass balance and mean observed values. Results showed ultrafine mode particles with diameter smaller than 100 nm with a relatively K 2 SO 4 and Na 2 SO 4 large amount inducing further growth by diffusive condensation and coagulation of low-volatile organic compounds. The process could lead to modifications of aerosol size distribution and also to formation of more active Cloud Condensation Nuclei (CCN) due to the formation of aerosols with considerably increase of hygro-scopicity (>40%). The contribution from BC can decreases up to 40% of the observed hygroscopicities values of particles around 100 nm in diameter. Moreover, we present a parameterization based on aerosol mass fraction to accurately predict κ derived from data of Aerosol Mass Spectrometer (AMS) collected in urban pollution in Brazil. Results are compared to hygro-scopicity derived from observations of the pollution plume downwind Manaus, on the northern region of Brazil. Both cases were analogous indicating that, despite the fact of receiving influences of organic components from the forest, the pollution plume of Manaus shows the same characteristics of hygroscopicity, and can be modeled following the same parameterization.
The formation of sulfate and secondary organic aerosol mass in the aqueous phase (aqSOA) of cloud and fog droplets can significantly contribute to ambient aerosol mass. While tracer compounds give evidence that aqueous-phase processing occurred, they do not reveal the extent to which particle properties have been modified in terms of mass, chemical composition, hygroscopicity, and oxidation state. We analyze data from several field experiments and model studies for six air mass types (urban, biogenic, marine, wild fire biomass burning, agricultural biomass burning, and background air) using aerosol size and composition measurements for particles 13–850 nm in diameter. We focus on the trends of changes in mass, hygroscopicity parameter κ, and oxygen-to-carbon (O / C) ratio due to chemical cloud processing. We find that the modification of these parameters upon cloud processing is most evident in urban, marine, and biogenic air masses, i.e., air masses that are more polluted than very clean air (background air) but cleaner than heavily polluted plumes as encountered during biomass burning. Based on these trends, we suggest that the mass ratio (Rtot) of the potential aerosol sulfate and aqSOA mass to the initial aerosol mass can be used to predict whether chemical cloud processing will be detectable. Scenarios in which this ratio exceeds Rtot∼0.5 are the most likely ones in which clouds can significantly change aerosol parameters. It should be noted that the absolute value of Rtot depends on the considered size range of particles. Rtot is dominated by the addition of sulfate (Rsulf) in all scenarios due to the more efficient conversion of SO2 to sulfate compared to aqSOA formation from organic gases. As the formation processes of aqSOA are still poorly understood, the estimate of RaqSOA is likely associated with large uncertainties. Comparison to Rtot values as calculated for ambient data at different locations validates the applicability of the concept to predict a chemical cloud-processing signature in selected air masses.
This study was based on the determination of metals in particulate matter emitted by a typical diesel engine used by busses and trucks in Brazil. Emissions were sampled using a cascade impactor, and the engine was operated using diesel with 5% (B5), 10% (B10), 15% (B15), and 20% (B20) of biodiesel. The particulate matter was stratified in different sizes, i.e., 18, 5.6, 3.2, 1.8, 1.0, 0.560, 0.320, 0.180, 0.100, and 0.056 μm. Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V, and Zn with concentrations within 10 to 1000 ng m⁻³ were determined. The results indicate a trend in the prevalence of lead, nickel, and chromium in coarse particles and nanoparticles in all blends of fuels. By comparing the results of B5, B10, B15, and B20 fuels, we can confirm that the addition of biodiesel to diesel promotes a reduction of emissions, and by comparing the behavior of the concentration of all elements analyzed, emissions by B10 and B15 fuels are similar, while B5 and B20 suffer significant changes during the process of combustion. Multivariate statistical analysis was used, and it indicates possible sources in three clusters, one for Ni, other for Cr-Mn, and the last one for other metals.
Recent studies demonstrate that Black Carbon (BC) pollution in economically developing megacities remain higher than the values, which the World Health Organization considers to be safe. Despite the scientific evidence of the degrees of BC exposure, there is still a lack of understanding on how the severe levels of BC pollution affect human health in these regions. We consider information on the respiratory tract deposition dose (DD) of BC to be essential in understanding the link between personal exposure to air pollutants and corresponding health effects. In this work, we combine data on fine and ultrafine refractory particle number concentrations (BC proxy), and activity patterns to derive the respiratory tract deposited amounts of BC particles for the population of the highly polluted metropolitan area of Manila, Philippines. We calculated the total DD of refractory particles based on three metrics: refractory particle number, surface area, and mass concentrations. The calculated DD of total refractory particle number in Metro Manila was found to be 1.6 to 17 times higher than average values reported from Europe and the U.S. In the case of Manila, ultrafine particles smaller than 100 nm accounted for more than 90% of the total deposited refractory particle dose in terms of particle number. This work is a first attempt to quantitatively evaluate the DD of refractory particles and raise awareness in assessing pollution-related health effects in developing megacities. We demonstrate that the majority of the population may be highly affected by BC pollution, which is known to have negative health outcomes if no actions are taken to mitigate its emission. For the governments of such metropolitan areas, we suggest to revise currently existing environmental legislation, raise public awareness, and to establish supplementary monitoring of black carbon in parallel to already existing PM10 and PM2.5 measures.
The present investigation focus on the characterization and leachability evaluation of medical wastes incineration ashes and that of their glasses, produced during vitrification with soda lime recycled glass (SLRG). Two types of ashes were examined: A Fly Ash (MFA) derived from the incinerator waste gases de-dusting system (fabric filter dust collector), and a Bottom Ash (MBA) produced from the heavier particles of the agglomerated remaining matter, which are precipitated and accumulated usually in the combustion chamber. Glasses of various syntheses were obtained during the MFA and MBA vitrification with various amounts of silica scrap (20, 25 and 30 wt% for MBA and 50, 55 and 60 wt% for MFA). The characterization of both ashes and that of their vitreous products was carried out by means of chemical analysis and mineralogical analysis by X-ray diffraction. MFA microstructure and morphological characteristics were examined by scanning electron microscopy and transmission electron microscopy, whereas the corresponding of MBA and the produced glasses were studied in polished section through scanning electron microscopy. Their behaviour during leaching was determined by the Toxicity Characteristic Leaching Procedure test and the EN 12457-2 compliance leaching test and according to the results both ashes should be treated as hazardous wastes and in case of landfilling they should be disposed of at appropriate, regulation-prescribed waste dumps. On the other hand in case of their vitreous outgrowths, the trace elements detected in the leachates were well below the corresponding regulatory limits.
Ultrafine soot particles (black carbon, BC) in urban environments are related to adverse respiratory and cardiovascular effects, increased cases of asthma and premature deaths. These problems are especially pronounced in developing megacities in South-East Asia, Latin America, and Africa, where unsustainable urbanization ant outdated environmental protection legislation resulted in severe degradation of urban air quality in terms of black carbon emission. Since ultrafine soot particles do often not lead to enhanced PM10 and PM2.5 mass concentration, the risks related to ultrafine particle pollution may therefore be significantly underestimated compared to the contribution of secondary aerosol constituents. To increase the awareness of the potential toxicological relevant problems of ultrafine black carbon particles, we conducted a case study in Metro Manila, the capital of the Philippines.
An integrated aerosol-analytical-system was deployed in Nanjing, a megacity in the Yangtze-River-Delta, to measure size-resolved aerosol mixing states, effective densities, CCN activities, and chemical composition in August 2013. It was found that aerosols were predominantly internally mixed. The average effective densities were 1.38±0.09, 1.48±0.08 and 1.53±0.07 g cm-3 for 50, 80 and 120nm particles, respectively. Although black carbon (BC) represented only 0.3%, 1.6%, 3.3% of the particle mass, on average it was present in 7%, 38% and 47% of the total particle number concentration at 50, 80 and 120 nm, respectively, indicating that BC particles may contribute significantly to the total atmospheric aerosol population. Externally mixed BC was only occasionally observed with an effective density of 0.67-0.97 g cm-3. Aerosols sampled generally exhibited a relatively high CCN activity and hygroscopicity (κ = 0.35±0.13). Both newly formed particles and freshly emitted BC particles were observed to age rapidly from photochemical processes, with a significant enhancement in the particle CCN activity and increase in the effective density. Aerosols influenced by four different air masses presented similar CCN activation, indicating that CCN activation would be primarily dependent on the particle size rather than the particle origin (and hence original composition). Our results suggest that under highly active photochemical conditions as encountered in this study, particles from both local sources and regional transport can be rapidly converted into efficient CCN by photochemical aging, thereby making important contributions to the atmospheric CCN budget and exerting profound implications on aerosol indirect climate forcing.