A tentative study of urban and suburban fine particles (PM2.5) collected in Ouagadougou,Burkina Faso

The aim of the study was to determine the mass, black carbon (BC), and elemental concentrations in fine particles (PM_2.5) and their variations at two sites in Ouagadougou, the capital city of Burkina Faso. The weather situation in Ouagadougou during the field campaign was dominated by high pressure with variable cloudiness and no precipitation. Diurnal temperatures varied between 19 and 38 °C and relative humidity between 10 and 60%. Winds in Ouagadougou were generally coming in from the north, showing a diurnal pattern with gusts of up to 6 m/s during daytime, while evenings and nights were calmer with very stable atmospheric conditions. However, during part of this field campaign, a period of nighttime moderately stable atmospheric conditions occurred with increased wind speed and more easterly winds. Cyclones were used for the PM_2.5 particle collection at both sites. The elemental analysis was done using energy dispersive x‐ray fluorescence (EDXRF) spectroscopy. Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Br, Rb, Sr, and Pb were identified and quantified in most of the samples. The particle mass concentration was 27–164 µg/m³ while BC varied between 1.3 and 8.2 µg/m³. No influence of leaded gasoline was found. Soil dust was identified as a major component of the particles, which was confirmed by comparing with the elements in a soil sample. A significant difference in elemental, BC, and mass concentrations was seen between periods with very stable and moderately stable atmospheric conditions. Copyright © 2009 John Wiley & Sons, Ltd.     

Elemental analysis of particulate matter in a metal workshop and of biological samples from exposed workers

During metal welding and cutting, large amounts of particulate matter (PM) are produced that might represent a significant health risk for the exposed workers. In the present pilot study, we performed an elemental analysis of fine PM collected in a metal workshop. Also, elemental analysis of the hair and nail samples collected from workers exposed to the workshop dust and control group was done. Concentrations of 15 elements in PM were measured with X‐Ray Fluorescence (XRF) and Particle Induced X‐ray Emission (PIXE), whereas inductively coupled plasma mass spectrometry (ICP‐MS) was used to determine 12 elements in hair and nail samples. Mean 8‐hr concentrations of PM_2.5, Fe, and Mn in the vicinity of welders were up to 1803, 860, and 30 μg/m³, respectively, whereas in the nearby city, daily PM_2.5 concentrations are on average 11 μg/m³. We found that several elements, especially Fe and Mn, had substantially higher concentrations in hair and nail samples of exposed workers than in the control group, which indicates the accumulation of metals in workers' tissues, although limit values were not exceeded.     

Elemental content of aerosol particles in an underground tram station

Particulate matter is an important air pollutant, especially in closed environments like a tunnel. The aim of this study was to determine the mass, black carbon, and elemental concentrations of particulate matter of two size fractions at an underground tram station in Hammarkullen, Gothenburg, Sweden. Samples were collected during June 2007 using a dichotomous virtual impactor separating the sampled aerosol particles into coarse (PM_(2.5–10)) and fine (PM_2.5) fractions. To minimize the possible influence of waiting passengers, the platform for trams going towards the suburb Angered was chosen. The elemental analysis of the samples, collected on Teflon filters, was carried out using energy dispersive x‐ray fluorescence (EDXRF) spectrometry, resulting in concentrations of 14 elements in most of the samples. Principal component analysis (PCA) was applied to identify possible sources for the elements in the particles. Owing to the tunnel environment, the elemental difference between the fine and coarse particle fractions was not as large as that in similar particles collected under normal outdoor ambient conditions. Likewise, the influence of the local weather situation was not significant. Particle content from the tram traffic was identified by PCA, with Fe being the major element in both coarse and fine particles. The particle mass concentration was higher in the tunnel compared to the ambient concentration at the monitoring station Femman in downtown Gothenburg. In some days, the mass concentration exceeded the Swedish daily ambient air quality standard of 50 µg m^?3, but it was lower than the limits in the environmental work act, 5 mg m^?3. Copyright © 2009 John Wiley & Sons, Ltd.     

Identification of elemental composition of PM2.5 collected in Makkah,Saudi Arabia,using EDXRF

Makkah city, Saudi Arabia, represents the most attractive place for religious tourism for Muslims all over the world. More than 15 million visitors come to the city per year, especially during Hajj (pilgrimage) and Ramadan seasons. Due to the lack of air quality assessment data for Makkah, measurement of different pollutants in Makkah is of great interest. In the present work, airborne particulate matter with aerodynamic diameter equal to or less than 2.5 µm (PM_2.5) has been collected from two different sites in the city, namely the Grand mosque and Al‐Shraie, from December 2012 to January 2014 covering the different seasons of the year. The average mass concentrations at the sites are comparable, 48 ± 28 µg/m³ and 53 ± 27 µg/m³ for the Grand mosque and Al‐Shraie sites, respectively. For quantitative elemental analysis, energy dispersive X‐ray fluorescence (EDXRF) spectrometry was used. Twenty elements (Si, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Se, Br, Rb, Sr and Pb) were quantified in the PM_2.5 samples. Fortunately, the obtained results of Pb and S are below the maximum allowance level of European commission for air quality. However, the average concentration of Ni in both sites is close to the maximum allowance level 20 ng/m³ and the Ni concentration reaches 25 ng/m³ at Grand mosque site during August 2013. Based on the Positive Matrix Factorization (PMF) analysis, four source factors were found, some signalling mixed sources, showing the main influence from mineral dust, anthropogenic/industrial sources and a marine source. Copyright © 2017 John Wiley & Sons, Ltd.     

Chemical composition and mass closure for PM10 aerosols during the 2005 dry season at a rural site in Morogoro,Tanzania

An intensive aerosol field campaign was carried out from 11 July to 11 August 2005 (dry season) at a rural site in Morogoro, Tanzania. The objectives were to determine the chemical composition of the atmospheric particulate matter (PM) and to examine to which extent the gravimetric PM mass can be explained by the measured aerosol components. Two low‐volume filter samplers were deployed, a PM₁₀ filter holder with two Whatman QM‐A quartz fibre filters in series and a Gent PM₁₀ stacked filter unit (SFU) sampler with coarse and fine Nuclepore polycarbonate filters. The samplers operated in parallel and a total of 51 parallel collections were made. All samples were analysed for the PM mass by weighing. Depending on the sampler type and/or collection substrate, further analyses were performed for 25 elements by particle‐induced x‐ray emission spectrometry, for major water‐soluble inorganic ions by ion chromatography, and for organic carbon and elemental carbon by a thermal—optical transmission technique. The PM₁₀ mass, as derived from the SFU samples, was, on an average, 46 ± 12 µg/m³. Aerosol chemical mass closure calculations were made for this PM₁₀ mass; eight aerosol components were considered and they explained 93% of the average PM₁₀ mass. Organic matter (OM) and crustal matter were the dominant aerosol components; they accounted for, on an average, 44% and 33%, respectively, of the PM₁₀ aerosol. The large contribution from OM is thought to originate mainly from the burning of biomass, especially of charcoal and agricultural residues. Copyright © 2009 John Wiley & Sons, Ltd.     

Evaluation of the concentration of chemical elements in suspended particulate matter inside a small bronze and iron foundry industry,using a streaker sampler and EDXRF

The aim of this study was to determine and evaluate the temporal profiles of the concentration of chemical elements in the suspended particulate matter present inside a small bronze and an iron foundry industry. To collect the samples, we used a streaker sampler that separates particles with aerodynamic diameters smaller than 10 µm (PM₁₀) in two fractions: fine (particles with aerodynamic diameters less than 2.5 µm; PM_2.5) and coarse (between 2.5 µm and less than 10 µm; PM_10–2.5). The collection of samples was taken every 20 min during a total time of 8 and 5 h of molding and casting of bronze and iron, respectively. The samples collected in the form of strips on a filter (fine fraction) and an impactor (coarse fraction) were analyzed by the energy dispersive X‐ray fluorescence technique. In the excitation, an X‐ray tube with Mo target and Zr filter was used, operated at 30 mA/30 kV. For detecting the characteristic of X‐rays, a semiconductor Si(Li) detector was used, coupled to a multi‐channel spectrometer, with a 300 s excitation/detection time. The results of the temporal profiles of chemical element concentrations in coarse and fine fractions were discussed and compared with the maximum levels set by the Brazilian and international environmental agencies. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of the torrefaction on the emission of PM10 from combustion of rice husk and its blends with a lignite

Torrefaction is a competitive biomass pretreatment technology. However, its impacts on particulate matter (PM) formation during biomass combustion and co-combustion with coal have little been investigated. This work provides new data on the formation of PM₁₀ (particulate matter with aerodynamic diameters less than or equal to 10 µm) from combustion of raw (RH), torrefied rice husk (TRH) and their blends with a lignite (SZ). All combustion experiments were carried out on a drop-tube furnace at 1300 °C and in air. The combustion-generated PM₁₀ was collected by a Dekati low pressure impactor and classified into 14 size fractions for further quantification and characterization. The results indicate that, compared with the RH, the TRH-derived PM₁₀₊ (particle size above 10?µm) contains more alkalis, leading to a decrease in the production of PM₁ (particle size below 1?µm). During co-combustion, fuel interactions promote the transformation of alkali chlorides to aluminosilicates. A considerable amount of water-soluble Ca and P in PM₁ transforms to PM_1–10 (particle size between 1–10?µm). As a result, the production of PM₁ (on an ash basis) decreases while that of PM_1–10 increases. Co-combustion of coal with torrefied rice husk is found to generate less PM₁ but more PM_1–10 than that with raw rice husk.     

Measurements and modelling of oxy-fuel coal combustion

Oxy-fuel combustion is one of the most promising technologies to isolate efficiently and economically CO₂ emissions in coal combustion for the ready carbon sequestration. The high proportions of both H₂O and CO₂ in the furnace have complex impacts on flame characteristics (ignition, burnout, and heat transfer), pollutant emissions (NO_x, SO_x, and particulate matter), and operational concerns (ash deposition, fouling/slagging). In contrast to the existing literature, this review focuses on fundamental studies on both diagnostics and modelling aspects of bench- or lab-scale oxy-fuel combustion and, particularly, gives attention to the correlations among combustion characteristics, pollutant formation, and operational ash concerns. First, the influences of temperature and species concentrations (e.g., O₂, H₂O) on coal ignition, volatile combustion and char burning processes, for air- and oxy-firing, are comparatively evaluated and modelled, on the basis of data from optically-accessible set-ups including flat-flame burner, drop-tube furnace, and down-fired furnace. Then, the correlations of combustion-generated particulate/NO_x emissions with changes of combustion characteristics in both air and oxy-fuel firing modes are summarized. Additionally, ash deposition propensity, as well as its relation to the formation of fine particulates (i.e. PM_0.2, PM₁ and PM₁₀), for both modes are overviewed. Finally, future research topics are discussed. Fundamental oxy-fuel combustion research may provide an ideal alternative for validating CFD simulations toward industrial applications.     

Mechanistic investigation into particulate matter formation during air and oxyfuel combustion of formulated water-soluble fractions of bio-oil

This paper reports a systematic study on the formation of particulate matter with diameter of <10 µm (i.e., PM₁₀) during the combustion of two formulated water-soluble fractions (FWSFs) of bio-oil in a drop-tube-furnace (DTF) at 1400 °C under air or oxyfuel (30%O₂/70%CO₂) conditions. FWSF-1 was an organic-free calcium chloride solution with a calcium concentration similar to that in the bio-oil. FWSF-2 was formulated from the compositions of major organics in bio-oil WSF, doped with calcium chloride at the same concentration. The results suggest that similar to bio-oil combustion, the FWSF combustion produces mainly particulate matter with diameter of between 0.1 and 10 µm (i.e., PM_0.1–10). Since there are no combustibles in the organic-free FWSF-1, the PM is produced via droplet evaporation followed by crystallization, fusion and further reactions to form CaO (in air or argon) or partially CaCO₃ (under oxyfuel condition). With the addition of organics, FWSF-2 combustion produces PM₁₀ shifting to smaller sizes due to extensive break up of droplets via microexplosion. Sprays with larger droplet size produce PM₁₀ with increased sizes. The results show that upon cooling CaO produced during combustion in air can react with HCl gas to form CaCl₂ in PM_0.1. The predicted PSDs of PM₁₀ based on the assumption that one droplet produces one PM particle is considerably larger than experimentally-measured PSDs of PM₁₀ during the combustion of FWSFs, confirming that breakup of spray droplets takes place and such breakup is extensive for FWSF-2 when organics are present in the fuel.     

Determination of the concentration of aerosol particles in a vertical atmospheric column from satellite measurements of the spectral optical depth

We propose a method for fast retrieval of the inhalable particle concentration (PM_2.5 and PM₁₀) in a vertical atmospheric column from satellite measurements of the aerosol optical depth (AOD) without using a priori assumptions concerning the refractive index and the aerosol particle size distribution function. The method is based on a polynomial regression between PM_2.5, PM₁₀, and AOD at the wavelengths 466 nm and 644 nm, established from AERONET data. We have studied the sensitivity of the method to errors in the optical measurements and have estimated the errors in retrieval of PM_2.5 and PM₁₀ for different atmospheric situations. We carry out parametrization of the regressions on the value of the integrated air moisture content.     

Elemental characterization and source identification of the near-road PM2.5 using EDXRF in Chengdu,China

To characterize the elemental composition and source apportionment of aerosols in roadside area, particulate matters with aerodynamic diameter less than 2.5 μm (PM_2.5) were collected in close proximity to a road from September 2017 to February 2018 in downtown Chengdu, China. An energy-dispersive X-ray fluorescence spectrometer was used to quantify elemental constituents (Al, Si, S, K, Mn, Fe, Ni, Cu, Zn, As, and Pb) of PM_2.5 and was calibrated by in-house standards instead of commercial standards. The constructed calibration curves exhibited good linearity with all correlation coefficients greater than 0.98. The proposed calibration method proved to be reliable for the subsequent elemental analyses due to the satisfactory performance of u-score and precision that were validated by the certified reference materials (#2783). The results revealed that average PM_2.5 concentrations of 92.2 ± 45.6 and 113.2 ± 60.3 μg/m³ were respectively observed in autumn and in winter. The major trace elements identified were K, S, and Fe and the minor contributions were from Cu and As. Most crustal elements showed decline in winter except for K, and most anthropogenic elements showed increase in winter except for Ni. Using rotation factor analysis and cluster analysis based on the elemental dataset, four potential sources were identified: road dust, vehicular emissions, coal and biomass burning, and industrial emissions. This research will provide a better understanding of traffic-related PM_2.5 composition, and this can be used in the mitigation and prevention programs.     

Concentrations and sources of trace elements in particulate air pollution,Dar es Salaam,Tanzania, studied by EDXRF

Trace elements in near‐ground atmospheric aerosols were investigated in Dar es Salaam, Tanzania. Particles were collected at two sites, one urban and one rural, during two months with different meteorological conditions. The samplers, dichotomous impactors, segregate the particles into two size fractions, fine (PM_2.5, d_a < 2.5 µ m) and coarse (2.5 < d_a < 10 µ m). A sharp cyclone was used to sample finer particles (PM₁, d_a < 1 µ m). Meteorological parameters were also examined at both sites. An EDXRF spectrometer, based on three‐axial geometry, was used for quantitative elemental analysis. Concentrations of elements heavier than phosphorus were determined. Also, the content of black carbon on the filters was measured with a reflectometer. The elemental concentrations were compared with respect to season and geographical location in the city. The levels of different species in Dar es Salaam were also compared with similar data from other African and European countries. This showed low values of Pb with respect to the size of the city and no legislation on the use of leaded petrol, that often is the main source of lead. High values of Cl were also found, as would be expected in a coastal city. The coarse particles in the air, originating from soil, had a different composition in Dar es Salaam than in Gaborone, Botswana, and the concentration of black carbon was higher than in other cities. On the basis of the data collected, source assignments were made and the following sources found; sea‐spray, soil, city road dust, biomass burning, industries and traffic. Comparing the concentrations of different elements in PM_2.5 and PM₁ revealed that black carbon, Zn, Pb, K and Br are present only in the smallest particles. Copyright © 2004 John Wiley & Sons, Ltd.     

Lead speciation of PM2.5 collected from Greater Cairo,Egypt and Zarqa,Jordan: An energy dispersive X-ray fluorescence and X-ray absorption near edge structure study

Fine aerosol particles with an aerodynamic diameter equal or less than 2.5 μm (PM_2.5) have been collected from two sites (residential and industrial) in Greater Cairo, Egypt and one site in Zarqa, Jordan. Based on the elemental quantitative analysis of PM_2.5 using energy dispersive X-ray fluorescence with Mo secondary target, Pb concentrations increased remarkably during winter season regardless of the sampling location. Moreover, it reached the maximum concentration at the industrial location of Greater Cairo, Egypt, and it equals 415 ± 485 ng/m³. The remarkable high standard deviation is due to the significant variation of Pb concentration from time to time during that winter season. Depending on the energy dispersive X-ray fluorescence results, specific PM_2.5 samples that have the highest concentration of Pb (two samples/location) have been selected for the X-ray absorption near edge structure measurements to estimate the oxidation state of Pb species. The X-ray absorption near edge structure measurements including 13 Pb references have been carried out at Pb-L₃ absorption edge (13.039 keV) using fluorescence mode. It was shown that PM_2.5 contains divalent and tetravalent lead in both industrial site in Greater Cairo, Egypt and urban site of Zarqa, Jordan although that of a residential area of Greater Cairo-Egypt is almost divalent lead.     

Effect of feedstock water leaching on ignition and PM1.0 emission during biomass combustion in a flat-flame burner reactor

In this work, the effects of feedstock water leaching on ignition and PM_1.0 emission during biomass combustion were studied, for the first time, in a Hencken flat-flame burner reactor (HFFBR). A high-speed video camera and high-resolution electrical low-pressure impactor were respectively employed to diagnose ignition and PM_1.0 along the height of the burner. The mineral composition of PM₁₀₊ was measured as a function of height to demonstrate the potassium release during the early stage of biomass combustion. The results show that water leaching does not change the functional group of the biomass (straw), but increases the BET surface area and pore volume. Water leaching removes 90% of the potassium and all the chlorine, reducing the same amount of PM_1.0 emission. The effect of water leaching on ignition delay observed in the flat-flame burner reactor agrees with the delay of biomass-devolatilization in TGA. Profiles of mineral composition in the PM₁₀₊ with height shows that a large amount of the potassium is released before biomass ignition. This indicates that, at realistic heating rates, the catalytic promotion of water-soluble minerals on biomass ignition is primarily through promoting devolatilization. The ignition delay of biomass particles caused by water leaching is more significant at lower temperature, e.g., ignition is delayed from 20 to 24?ms at 1000?°C, and from 9.2 to 10.2?ms at 1300?°C.     

Effect of water vapour on particulate matter emission during oxyfuel combustion of char and in situ volatiles generated from rapid pyrolysis of chromated-copper-arsenate-treated wood

This paper reports the effect of water vapour on particulate matter (PM) during the separate combustion of in situ volatiles and char generated from chromated-copper-arsenate-treated (CCAT) wood at 1300 °C. Combustion of in situ volatiles produces only PM with aerodynamic diameter?<1?µm (i.e., PM₁), dominantly PM with aerodynamic diameter?<0.1?µm (i.e., PM_0.1). Water vapour could significantly enhance the nucleation, coagulation and condensation of fine particles and reduce the capture of Na and K by the alumina reactor tube via reduced formation of alkali aluminates, leading to increases in both yield and modal diameter of PM_0.1. Water vapour could also enhance char fragmentation hence increase the yield of PM with aerodynamic diameter between 1 and 10?µm (i.e., PM_1–10) during char combustion. For trace elements, during in situ volatiles combustion, volatile elements (As, Cr, Ni, Cu and Pb) are only presented in PM₁ and water vapour alters the particle size distributions (PSDs) but has little effect on the yields of these trace elements. During char combustion, As, Cr, Cu and Ni are present in both PM₁ and PM_1–10 while the non-volatile Mn and Ti are only present in PM_1–10. Increasing water vapour content increases the yields of As, Cr, Cu, Ni, Mn and Ti in PM_1-10 due to enhanced char fragmentation. During char combustion, water vapour also originates less oxidising conditions locally for enhancing As release, promotes the generation of gaseous chromium oxyhydroxides and inhabits the production of NiCl₂ (g), leading to increased yields of As and Cr and decreased yield of Ni in PM_0.1.     

Identification of aerosol particle sources in semi‐rural area of Kwabenya,near Accra,Ghana, by EDXRF techniques

Small aerosol particles have for a long time been known to be harmful to humans, and are today regarded to cause a larger number of deaths than traffic accidents globally. Energy dispersive x‐ray fluorescence (EDXRF) is a well known method that has been used for identification of toxic as well as non‐toxic elements in the particles. The combination of elements will together with other information help to identify the sources and predict the effects of particles on environment and human health. The present work was conducted in Kwabenya, a suburb of the capital Accra of Ghana, which is frequently exposed to Harmattan dust from the Sahara–Sahel region. In total 171 filters each of PM2.5 and PM(2.5–10) were collected during 1 year. Levels of elements, black carbon (BC) and mass, were determined for both particle sizes. Principal component analysis (PCA) was performed on the datasets from Harmattan and non‐Harmattan periods. The daily average of PM10 was very high, 179 µg m^?3 and the BC contents were 4 µg m^?3. The presence of crustal elements was large in PM(2.5–10) as well as in PM2.5, and had a more than tenfold increase in PM(2.5–10) during the Harmattan period. Major characteristic elements for different sources were identified from correlation coefficients and regression analysis of the data. Sahara sand aerosol was the major source in both study periods, but influence from biomass burning, sea‐spray and metal industries was also observed. Copyright © 2009 John Wiley & Sons, Ltd.     

PM10 formation during the combustion of N2-char and CO2-char of Chinese coals

The formation of PM₁₀ (particles less than or equal to 10 μm in aerodynamic diameter) during char combustion in both air-firing and oxy-firing was investigated. Three Chinese coals of different ranks (i.e., DT bituminous coal, CF lignite, and YQ anthracite) were devolatilized at 1300 °C in N₂ and CO₂ atmosphere, respectively, in a drop tube furnace (DTF). The resulting N₂-chars and CO₂-chars were burned at 1300 °C in both air-firing (O₂/N₂ = 21/79) and oxy-firing (O₂/CO₂ = 21/79). The effects of char properties and combustion conditions on PM₁₀ formation during char combustion were studied. It was found that the formation modes and particle size distribution of PM₁₀ from char combustion whether in air-firing or in oxy-firing were similar to those from pulverized coal combustion. The significant amounts of PM_0.5 (particles less than or equal to 0.5 μm in aerodynamic diameter) generated from combustion of various chars suggested that the mineral matter left in the chars after coal devolatilization still had great contributions to the formation of ultrafine particles even during the char combustion stage. The concentration of PM₁₀ from char combustion in oxy-firing was generally less than that in air-firing. The properties of the CO₂-chars were different from those of the N₂-chars, which was likely due to gasification reactions coal particles experienced during devolatilization in CO₂ atmosphere. Regardless of the combustion modes, PM₁₀ formation in combustion of N₂-char and CO₂-char from the same coal was found to be significantly dependent on char properties. The difference in the PM₁₀ formation behavior between the N₂-char and CO₂-char was coal-type dependent.     

Emissions of PM10 from the co-combustion of high-Ca pyrolyzed biochar and high-Si coal under air and oxyfuel atmosphere

The single or co-combustion experiments of high-Ca pyrolyzed biochar and high-Si coal were carried out on a drop tube furnace (DTF) at 1300 °C under air and oxyfuel (CO₂:O₂=50:50, oxy50) conditions. The produced PM₁₀ (of an aerodynamic diameter of 10 µm or less) was analyzed to investigate the interactions during co-combustion. Due to the characteristics of the selected samples (low S and Cl), the PM₁ emissions including PM_0.1 and PM_0.1–1 are very low during single combustion, except for the PM_0.1–1 emission during the combustion of biochar under oxy50 condition because of the massive partitioning of Mg, Ca and Fe. The interaction during co-combustion was observed to mainly occur in the generation of PM_1–10, and also slightly occur in the formation of PM_0.1–1 under oxy50 condition. The capture of Mg, Ca, and Fe from biochar by the Si-containing minerals in coal under the oxy50 condition results in a slight decrease in PM_0.1–1 during co-combustion. The higher the proportion of coal blended, the more obvious the reduction of elements. As for the formation of PM_1–10 during co-combustion, high-melting minerals of biochar would weaken the coalescence of minerals in coal to cause more PM₁₀, while the large mineral grains of coal would capture the minerals in biochar to generate more PM₁₀₊. Under the competition of the above two types of interactions, the experimental value of PM_1–10 yields was almost consistent with the theoretically calculated value, except for blended ratio of 80:20 (coal: biochar, air) or 50:50 (oxy50) with prior interaction predominating.     

Regression approach to analyzing the informativity and interpretation of aerosol optical measurements

A regression approach is proposed for planning aerosol optical experiments and for estimating the potential accuracy of the derived microphysical parameters of atmospheric aerosols taking the features of the apparatus and the available a priori information into account. This method is used to evaluate the informativity of polarization spectronephelometer measurements with respect to the microphysical parameters of continental aerosols. The problem of choosing the most informative aerosol optical characteristics with respect to the mass concentrations of the PM _2.5 and PM ₁₀ respirable fractions is examined and regression equations are derived for determining these concentrations from lidar probe data at wavelengths of 0.355 and 1.064 μm, as well as from reference measurements at 0.37 and 0.98 μm. The theoretical results obtained here are compared with AERONET data.     

Environmental pollution due to black carbon aerosols and its impacts in a tropical urban city

Black carbon (BC) has become the subject of interest in the recent years for a variety of reasons. BC aerosol may cause environmental as well as harmful health effects in densely inhabited regions. BC is a strong absorber of radiation in the visible and near-infrared part of the spectrum, where most of the solar energy is distributed. Black carbon is emitted into the atmosphere as a byproduct of all combustion processes, viz., vegetation burning, industrial effluents, motor vehicle exhausts, etc. In this paper, we present results from our measurements on BC aerosols, total aerosol mass concentration, and aerosol optical depth over an urban environment, namely Hyderabad during January-May, 2003. Diurnal variations of BC suggest that high BC concentrations are observed during 6:00-9:00 h and 19:00-23:00 h. Weekday variations of BC suggest that the day average BC concentrations increases gradually from Monday to Wednesday and gradually decreases from Thursday to Sunday. Fraction of BC to total mass concentration has been observed to be 7%. BC showed positive correlation with total mass concentration and aerosol optical depth at 500 nm. Radiative transfer calculations suggest that during January-May, diurnal averaged aerosol forcing at the surface was calculated to be −33 Wm⁻² and at the top of the atmosphere (TOA) it is to be +9 Wm⁻².