Showing papers on "Particulates published in 2007"
TL;DR: The identified ambient signature of wood burning was found to be very similar to the mass spectral signature obtained during the burning of chestnut wood samples in a small stove and also to the spectrum of levoglucosan.
Abstract: Throughout the winter months, the village of Roveredo, Switzerland, frequently experiences strong temperature inversions that contribute to elevated levels of particulate matter. Wood is used as fuel for 75% of the domestic heating installations in Roveredo, which makes it a suitable location to study wood burning emissions in the atmosphere in winter. An Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) was used to characterize the composition of the submicrometer, non-refractory aerosol particles at this location during two field campaigns in March and December 2005. Wood burning was found to be a major source of aerosols at this location in winter. Organics dominated the composition of the aerosols from this source, contributing up to 85% of the total AMS measured mass during the afternoon and evening hours. Carbonaceous particle analysis showed that organic carbon composed up to 86% of the total carbon mass collected at evening times. Results from 14C isotope determination revealed that up to 94% ...
426 citations
TL;DR: In this paper, the first estimates for the global average emission rates of fungal spores were presented, showing that fungi which actively discharge their spores with liquids into the air are a major source of primary biogenic aerosol particles and components.
Abstract: Biogenic aerosols play important roles in atmospheric chemistry physics, the biosphere, climate, and public health. Here, we show that fungi which actively discharge their spores with liquids into the air, in particular actively wet spore discharging Ascomycota (AAM) and actively wet spore discharging Basidiomycota (ABM), are a major source of primary biogenic aerosol particles and components. We present the first estimates for the global average emission rates of fungal spores.
Measurement results and budget calculations based on investigations in Amazonia (Balbina, Brazil, July 2001) indicate that the spores of AAM and ABM may account for a large proportion of coarse particulate matter in tropical rainforest regions during the wet season (0.7–2.3 μg m^−3). For the particle diameter range of 1–10 μm, the estimated proportions are ~25% during day-time, ~45% at night, and ~35% on average. For the sugar alcohol mannitol, the budget calculations indicate that it is suitable for use as a molecular tracer for actively wet discharged basidiospores (ABS). ABM emissions seem to account for most of the atmospheric abundance of mannitol (10–68 ng m^−3), and can explain the observed diurnal cycle (higher abundance at night). ABM emissions of hexose carbohydrates might also account for a significant proportion of glucose and fructose in air particulate matter (7–49 ng m^−3), but the literature-derived ratios are not consistent with the observed diurnal cycle (lower abundance at night). AAM emissions appear to account for a large proportion of potassium in air particulate matter over tropical rainforest regions during the wet season (17–43 ng m^−3), and they can also explain the observed diurnal cycle (higher abundance at night). The results of our investigations and budget calculations for tropical rainforest aerosols are consistent with measurements performed at other locations.
Based on the average abundance of mannitol reported for extratropical continental boundary layer air (~25 ng m^−3), we have also calculated a value of ~17 Tg yr^−1 as a first estimate for the global average emission rate of ABS over land surfaces, which is consistent with the typically observed concentrations of ABS (~10³–10^4 m^−3; ~0.1–1 μg m^−3). The global average atmospheric abundance and emission rate of total fungal spores, including wet and dry discharged species, are estimated to be higher by a factor of about three, i.e. 1 μg m^−3 and ~50 Tg yr^−1. Comparisons with estimated rates of emission and formation of other major types of organic aerosol (~47 Tg yr^−1 of anthropogenic primary organic aerosol; 12–70 Tg yr^−1 of secondary organic aerosol) indicate that emissions from fungi should be taken into account as a significant global source of organic aerosol. The effects of fungal spores and related chemical components might be particularly important in tropical regions, where both physicochemical processes in the atmosphere and biological activity at the Earth's surface are particularly intense, and where the abundance of fungal spores and related chemical compounds are typically higher than in extratropical regions.
417 citations
TL;DR: Field measurements were conducted to determine particulate emissions and trace gas emissions from open burning of wheat straw and maize stover, two major agricultural residues in China, and chemical composition analysis indicates that PM2.5 is largely composed of carbon, K, and Cl.
Abstract: Field measurements were conducted to determine particulate emissions and trace gas emissions, including CO2, CO, CH4, NMHCs, NOx, NH3, N2O, and SO2, from open burning of wheat straw and maize stover, two major agricultural residues in China. The headfire ignition technique was adopted, and sampling was performed downwind from the agricultural fire. Particulate matter (PM) and gas emission factors were determined using the carbon mass-balance method. Particle mass size distributions show a prominent accumulation mode peak at 0.26−0.38 μm. Submicron particles dominate PM emissions. Most measured chemical species measured show a similar size distribution as PM. Chemical composition analysis indicates that PM2.5 is largely composed of carbon, K, and Cl. PM2.5 emission factors of wheat straw and maize stover are 7.6 ± 4.1 g/kg and 11.7 ± 1.0 g/kg, respectively. It also indicates that 12.1−24.2% of N in biomass is released as nitrogen-based trace gases and 11.0−24.9% of fuel S is emitted as SO2.
376 citations
TL;DR: In this paper, the authors examined the distribution and the elemental and isotopic composition of organic matter in nine tidal estuaries along the Atlantic coast of Europe (Elbe, Ems, Thames, Rhine, Scheldt, Loire, Gironde, Douro and Sado).
311 citations
TL;DR: Data from the Women's Health Initiative (WHI) observational study is reported on, which greatly expands the understanding of how fine particulate pollution affects health.
Abstract: More than a decade ago, prospective epidemiologic studies showed that mortality was increased among people living in communities with elevated concentrations of fine particulate air pollution.1,2 Subsequent research has shown that particulate air pollution is statistically and mechanistically linked to increased cardiovascular disease.3 New data are beginning to shed light on which persons are at heightened risk. In this issue of the Journal, Miller et al.4 report on data from the Women's Health Initiative (WHI) observational study, which greatly expands our understanding of how fine particulate pollution affects health. Earlier long-term prospective cohort studies showed an association between levels . . .
289 citations
TL;DR: It is found that the lower-bound ammonia savings potential in the winter is $8,000 per ton NH3; therefore, many currently available ammonia control technologies are cost-effective compared to current controls on SO2 and NO(x) sources.
Abstract: Current regulation aimed at reducing inorganic atmospheric fine particulate matter (PM2.5) is focused on reductions in sulfur dioxide (SO2) and oxides of nitrogen (NO(x) = NO + NO2); however, controls on these pollutants are likely to increase in cost and decrease in effectiveness in the future. A supplementary strategy is reduction in ammonia (NH3) emissions, yet an evaluation of controls on ammonia has been limited by uncertainties in emission levels and in the cost of control technologies. We use state of the science emission inventories, an emission-based regional air quality model, and an explicit treatment of uncertainty to estimate the cost-effectiveness and uncertainty of ammonia emission reductions on inorganic particulate matter in the Eastern United States. Since a paucity of data on agricultural operations precludes a direct calculation of the costs of ammonia control, we calculate the "ammonia savings potential", defined as the minimum cost of applying SO2 and NO(x) emission controls in order to achieve the same reduction in ambient inorganic PM2.5 concentration as obtained from a 1 ton decrease in ammonia emissions. Using 250 scenarios of NH3, SO2, and NO(x) emission reductions, we calculate the least-cost SO2 and NO(x) control scenarios that achieve the same reduction in ambient inorganic PM2.5 concentration as a decrease in ammonia emissions. We find that the lower-bound ammonia savings potential in the winter is $8,000 per ton NH3; therefore, many currently available ammonia control technologies are cost-effective compared to current controls on SO2 and NO(x) sources. Larger reductions in winter inorganic particulate matter are available at lower cost through controls on ammonia emissions.
242 citations
TL;DR: In this article, the authors reviewed and summarized the levels of particulate air pollution, its elemental composition, its determinants, and its potential health effects in metro systems and found that the dust in the metro system was more toxic than ambient airborne particulates.
219 citations
TL;DR: In this paper, the authors used ECHAM5/MESSy1-MADE, a global climate model with detailed aerosol and cloud microphysics to study the climate impacts of international shipping.
Abstract: International shipping contributes significantly to the fuel consumption of all transport related activities. Specific emissions of pollutants such as sulfur dioxide (SO 2 ) per kg of fuel emitted are higher than for road transport or aviation. Besides gaseous pollutants, ships also emit various types of particulate matter. The aerosol impacts the Earth's radiation budget directly by scattering and absorbing the solar and thermal radiation and indirectly by changing cloud properties. Here we use ECHAM5/MESSy1-MADE, a global climate model with detailed aerosol and cloud microphysics to study the climate impacts of international shipping. The simulations show that emissions from ships significantly increase the cloud droplet number concentration of low marine water clouds by up to 5% to 30% depending on the ship emission inventory and the geographic region. Whereas the cloud liquid water content remains nearly unchanged in these simulations, effective radii of cloud droplets decrease, leading to cloud optical thickness increase of up to 5–10%. The sensitivity of the results is estimated by using three different emission inventories for present-day conditions. The sensitivity analysis reveals that shipping contributes to 2.3% to 3.6% of the total sulfate burden and 0.4% to 1.4% to the total black carbon burden in the year 2000 on the global mean. In addition to changes in aerosol chemical composition, shipping increases the aerosol number concentration, e.g. up to 25% in the size range of the accumulation mode (typically >0.1 μm) over the Atlantic. The total aerosol optical thickness over the Indian Ocean, the Gulf of Mexico and the Northeastern Pacific increases by up to 8–10% depending on the emission inventory. Changes in aerosol optical thickness caused by shipping induced modification of aerosol particle number concentration and chemical composition lead to a change in the shortwave radiation budget at the top of the atmosphere (ToA) under clear-sky condition of about −0.014 W/m² to −0.038 W/m² for a global annual average. The corresponding all-sky direct aerosol forcing ranges between −0.011 W/m² and −0.013 W/m². The indirect aerosol effect of ships on climate is found to be far larger than previously estimated. An indirect radiative effect of −0.19 W/m² to −0.60 W/m² (a change in the atmospheric shortwave radiative flux at ToA) is calculated here, contributing 17% to 39% of the total indirect effect of anthropogenic aerosols. This contribution is high because ship emissions are released in regions with frequent low marine clouds in an otherwise clean environment. In addition, the potential impact of particulate matter on the radiation budget is larger over the dark ocean surface than over polluted regions over land.
216 citations
TL;DR: The evolution of gaseous and particulate emission and combustion efficiency by burning wildland fuels in a laboratory combustion facility is investigated and should be considered in the development of PM and EC emission inventories for visibility and radiative forcing assessments.
Abstract: Combustion of wildland fuels represents a major source of particulate matter (PM) and light-absorbing elemental carbon (EC) on a national and global scale, but the emission factors and source profiles have not been well characterized with respect to different fuels and combustion phases. These uncertainties limit the accuracy of current emission inventories, smoke forecasts, and source apportionments. This study investigates the evolution of gaseous and particulate emission and combustion efficiency by burning wildland fuels in a laboratory combustion facility. Emission factors for carbon dioxide (CO2), carbon monoxide (CO), total hydrocarbon (THC), nitrogen oxides (NOx), PM, light extinction and absorption cross sections, and spectral scattering cross sections specific to flaming and smoldering phases are reported. Emission factors are generally reproducible within ±20% during the flaming phase, which, despite its short duration, dominates the carbon emission (mostly in the form of CO2) and the productio...
202 citations
TL;DR: In this paper, the major source of PM10 in six northern China cities (Urumqi, Yinchuan, Taiyuan, Anyang, Tianjin and Jinan) was investigated.
188 citations
TL;DR: There is strong evidence that lag 1 exposures to particulate matter continue to be associated with increased mortality and weak indication that the lag 1 effects of particulates matter declined during 1987-2000 and that this decline occurred mostly in the eastern United States.
Abstract: Evaluation of the public health impact of air quality regulations, referred to as accountability research, is increasingly viewed as a necessary component of responsible governmental policy interventions. The authors present an example of accountability assessment based on evaluating change in the short-term effect of airborne particles over a period of increasingly stringent regulation that might have changed the chemical composition and toxicity of these particles. They used updated data and methods of the National Morbidity Mortality Air Pollution Study to estimate national average relative rates of the effects of particulate matter � 10 lm in aerodynamic diameter on all-cause, cardiovascular, and respiratory mortality and on other-cause mortality for 1987–2000. They estimated national average relative rates of the effects of particulate matter � 2.5 lm in aerodynamic diameter on all-cause mortality for 1999–2000. The authors found strong evidence that lag 1 exposures to particulate matter � 10 lm and � 2.5 lm in aerodynamic diameter continue to be associated with increased mortality. They also found a weak indication that the lag 1 effects of particulate matter � 10 lm in aerodynamic diameter on mortality declined during 1987–2000 and that this decline occurred mostly in the eastern United States. The methodology presented can be used to track the health effects of air pollution routinely on regional and national scales. mortality; particulate matter; population surveillance; public policy; sentinel surveillance
TL;DR: In this article, the authors analyzed long-term surface global and diffuse solar radiation, aerosol single scattering albedo (SSA), and relative humidity (RH) from China.
Abstract: In this study, we analyzed long-term surface global and diffuse solar radiation, aerosol single scattering albedo (SSA), and relative humidity (RH) from China. Our analysis reveals that much of China experienced significant decreases in global solar radiation (GSR) and increases in diffuse solar radiation under cloud-free skies between the 1960s and 1980s. With RH and aerosol SSA being rather constant during that time period, we suggest that the increasing aerosol loading from emission of pollutants is responsible for the observed reduced GSR and increased diffuse radiation in cloud-free skies. Although pollutant emissions continue to increase after the 1980s, the increment of aerosol SSA since 1980s can partly explain the transition of GSR from a decreasing trend to no apparent trend around that time. Preliminary analysis is also provided on the potential role of RH in affecting the global and diffuse solar radiation reaching the earth surface.
TL;DR: A perspective on the current state of the science concerning health effects from a major group of chemical species found within PM2.5, namely common inorganic constituents, is provided, namely, sulfate, nitrate, and acidity.
Abstract: Ambient air particulate matter (PM) originates as either primary particles emitted directly into the atmosphere from a specific source or as secondary particles produced from atmospheric chemical reactions between precursor gases or between these gases and primary particles. PM can derive from both natural and anthropogenic sources, resulting in a complex chemical mix. The “fine” size mode of ambient PM, designated as PM2.5, is defined as comprising those particles having aerodynamic diameters below 2.5 μm. While the total mass of PM2.5 has been associated with adverse human health outcomes, the relationship between these and specific chemical components has not been resolved. This article provides a perspective on the current state of the science concerning health effects from a major group of chemical species found within PM2.5, namely common inorganic constituents. The specific chemical classes discussed herein are secondary inorganic species, namely, sulfate, nitrate, and acidity, and generally crusta...
TL;DR: Aerosols from wood burning versus other sources, particulate matter was collected at two Swiss Alpine valleys during winter. as mentioned in this paper showed that 88% and 65% of the total carbonaceous matter (including all other atoms than carbon) originated from non-fossil sources inside and outside of the village, respectively, which was mainly attributed to wood burning.
Abstract: [1] Within the project AEROWOOD (Aerosols from wood burning versus other sources), particulate matter was collected at two Swiss Alpine valleys during winter. Apportionment of aerosols from transit traffic and residential wood burning was performed using radiocarbon (14C) determinations of the organic carbon (OC) and elemental carbon (EC) fractions. On daily average, 88% and 65% of the total carbonaceous matter (including all other atoms than carbon) originated from non-fossil sources inside and outside of the village, respectively, which is mainly attributed to wood burning. These proportions were generally higher during the evening compared to morning hours, when traffic intensity waned and heating activities increased. 14C measurements of EC indicated episodes of both nearly pure traffic and wood-burning sources, respectively, of which the latter extreme has not been observed for EC under ambient conditions before. Results show that regulatory measures for the improvement of air quality must consider residential wood burning as an important source even in industrialized countries.
TL;DR: An energy policy and effective measures should be proposed to reduce particulate matter, especially PM2.5 pollution in Beijing to protect public health and the Beijing government also needs to cooperate with the other local governments to reduce high background level of particulate air pollution.
TL;DR: Sources apportionment using chemical mass balance model revealed that the most dominant source throughout the study period at residential site was coal combustion, while vehicular emission dominates at industrial site to PM(10).
TL;DR: The frequency of door-opening, taken as an index of staff and visitor movement, was the main negative predictor of over-threshold values of both fine and larger dust particles but, conversely, was a positive predictor of raised bacterial counts.
TL;DR: In this article, tail pipe emissions of a turbocharged common rail 2-stroke marine diesel engine (4RTX-3 from Wartsila) were investigated at various operating conditions and using two different fuels.
Abstract: This study presents results from tail pipe emissions of particulate matter from a turbocharged common rail 2-stroke marine diesel engine (4RTX-3 from Wartsila) investigated at various operating conditions and using two different fuels. Size distributions were measured with a SMPS (Scanning Mobility Particle Sizer). A thermodesorber (TD) was applied to remove volatile material. In addition, filter samples were taken for gravimetric and chemical analysis. The mean diameters of the particles ranged between 20–40 nm, which is considerably smaller than the diameter of particles known from 4-stroke diesel engines as used in cars. A TD operated at 400°C evaporated the majority of the particles. The particle mass is dominated by volatile organic material, the fraction of which is significantly higher than for engines in cars. A high nucleation mode was found instead of a pronounced accumulation mode as known from 4-stroke diesel engines.
TL;DR: The data indicate that the particulate diacids were produced over just a few hours close to the source; no significant production or destruction appears to have occurred during long-range transport to the ship.
Abstract: The mixing state of oxalic acid was measured in Asian outflow during ACE-Asia by direct shipboard measurements using an ATOFMS single-particle mass spectrometer. Oxalic and malonic acids were found to be predominantly internally mixed with mineral dust and aged sea salt particles. A persistent diurnal cycle of oxalic acid in mineral dust occurred for over 25 days in marine, polluted marine, and dust storm air masses. The preferential enrichment of diacids in mineral dust over carbonaceous particles and their diurnal behavior indicate a photochemical source of the diacids. Oxalate was only detected simultaneously with elevated aged dust particle counts. This suggests that the diurnal production of diacids most likely results from episodic atmospheric processing of the polluted dust aerosol. We propose a mechanism to explain these observations in which the photochemical oxidation of volatile organic compounds is followed by partitioning of the diacids and precursors to the alkaline Asian dust, with subsequent heterogeneous and aqueous oxidation. Our data indicate that the particulate diacids were produced over just a few hours close to the source; no significant production or destruction appears to have occurred during long-range transport to the ship. No evidence of extensive cloud processing of the sampled aerosol was found. This mixing state of diacids has important implications for the solubility and cloud nucleation properties of the dominant fraction of water-soluble organics and the bioavailability of iron in dust.
TL;DR: Some effective control measures were proposed to reduce the PM2.5 pollution in Beijing because the products of biomass burning for winter heating in the area around Beijing could enter the urban area during quasi-quiescent weather conditions.
TL;DR: Evaluating the relationship of daily changes in percent-predicted forced expiratory volume in 1 sec (FEV1) with personal and ambient air pollutant exposures found different sets of causal components are suggested by independence of FEV1 associations with personal PM2.5 mass from associations withpersonal NO2.
Abstract: BackgroundEpidemiologic studies have shown associations between asthma outcomes and outdoor air pollutants such as nitrogen dioxide and particulate matter mass < 2.5 μm in diameter (PM2.5). Indepen...
TL;DR: In this paper, fuel formulation exerted a strong influence on the properties of diesel particulates leading to differences in oxidation rate, which was especially significant when comparing soot derived from the combustion of soybean oil-derived biodiesel fuel (B100) and soot obtained from combustion of Fischer-Tropsch diesel fuel (FT).
Abstract: In this work, fuel formulation exerted a strong influence on the properties of diesel particulates leading to differences in oxidation rate. These differences were especially significant when comparing soot derived from the combustion of soybean oil-derived biodiesel fuel (B100) and soot obtained from combustion of a Fischer–Tropsch diesel fuel (FT). These 2 fuels mainly differ in fuel oxygen content. Although B100 soot possesses an initially ordered structure, it is 5 times more oxidatively reactive than FT soot. While the initial structure alone does not dictate the reactivity of diesel soot, the relative amount of initial oxygen groups is the more important factor governing the oxidation rate than the initial structure and pore size distribution. Therefore, incorporation of greater surface oxygen functionality in the B100 soot provides the means for more rapid oxidation and thereby enables efficient regeneration of the diesel particulate filter.
TL;DR: Gas-particle partition coefficients (K(p)'s) of n-alkane and PAHs were well correlated with the sub-cooled liquid vapour pressure (P(L)(0)) and indicate stronger sorption ofPAHs to aerosol particles compared with n-alksane, and both gas and particulate phase PAH concentrations decreased with increasing temperature.
TL;DR: In the representative gasoline fleet profiles, variation was further reduced, with cold-start or warm-start and the representation of smoker vehicles making a difference of approximately a factor of two in mass emission rate and EC/OC.
Abstract: As part of the Gasoline/Diesel PM Split Study, relatively large fleets of gasoline vehicles53 and diesel vehicles34 were tested on a chassis dynamometer to develop chemical source profiles for source attribution of atmospheric particulate matter in California’s South Coast Air Basin. Gasoline vehicles were tested in cold-start and warm-start conditions, and diesel vehicles were tested through several driving cycles. Tailpipe emissions of particulate matter were analyzed for organic tracer compounds, including hopanes, steranes, and polycyclic aromatic hydrocarbons. Large intervehicle variation was seen in emission rate and composition, and results were averaged to examine the impacts of vehicle ages, weight classes, and driving cycles on the variation. Average profiles, weighted by mass emission rate, had much lower uncertainty than that associated with intervehicle variation. Mass emission rates and elemental carbon/organic carbon (EC/OC) ratios for gasoline vehicle age classes were influenced m...
TL;DR: The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter participated in the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) mission during August-September 2006 as mentioned in this paper.
Abstract: The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter participated in the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) mission during August–September 2006. A particle-into-liquid sampler (PILS) coupled to ion chromatography was used to characterize the water-soluble ion composition of aerosol and cloud droplet residual particles (976 5-min PM_(1.0) samples in total). Sulfate and ammonium dominated the water-soluble mass (NH_4+ + SO_4^(2−) = 84 ± 14%), while organic acids contributed 3.4 ± 3.7%. The average NH_4^+:SO_4^(2−) molar ratio was 1.77 ± 0.85. Particulate concentrations of organic acids increased with decreasing carbon number from C_9 to C_2. Organic acids were most abundant above cloud, presumably as a result of aqueous phase chemistry in cloud droplets, followed by subsequent droplet evaporation above cloud tops; the main product of this chemistry was oxalic acid. The evolution of organic acids with increasing altitude in cloud provides evidence for the multistep nature of oxalic acid production; predictions from a cloud parcel model are consistent with the observed oxalate:glyoxylate ratio as a function of altitude in GoMACCS cumuli. Suppressed organic acid formation was observed in clouds with relatively acidic droplets, as determined by high particulate nitrate concentrations (presumably high HNO_3 levels too) and lower liquid water content, as compared to other cloud fields probed. In the Houston Ship Channel region, an area with significant volatile organic compound emissions, oxalate, acetate, formate, benzoate, and pyruvate, in decreasing order, were the most abundant organic acids. Photo-oxidation of m-xylene in laboratory chamber experiments leads to a particulate organic acid product distribution consistent with the Ship Channel area observations.
TL;DR: In this article, a study was conducted to understand the formation of inorganic secondary particles (nitrates and sulfates) in the atmosphere, and the study was designed to measure the atmospheric levels of NH þ þ ; Ca 2þ ; Mg 2 þ ; Na þ ; K þ ; NO � ; SO 2� 4 ; CI � ; NH3 gas ðÞ ; HNO3 gas Ã Ã Þ ; NO2 and PM10 PM2:5=PM10 ratio ¼ 0:74
Abstract: Levels of fine Particulate Matter (PMfine), SO2 and NOx are interlinked through atmospheric reactions to a large extent. NOx ,N H3 ,S O2, temperature and humidity are the important atmospheric constituents/conditions governing formation of fine particulate sulfates and nitrates. To understand the formation of inorganic secondary particles (nitrates and sulfates) in the atmosphere, a study was undertaken in Kanpur, India. Specifically, the study was designed to measure the atmospheric levels of NH þ ; Ca 2þ ; Mg 2þ ; Na þ ; K þ ; NO � ; SO 2� 4 ; CI � ; NH3 gas ðÞ ; HNO3 gas ðÞ ; NO2 and PM10 PM2:5=PM10 ratio ¼ 0:74
TL;DR: In this paper, the performance of several possible tracers for biomass burning is compared by using acetonitrile as a reference compound, and the correlations between the possible tracer and acetetitrile show that the use of K + as a tracer could result in bias because of the existence of other K + sources in urban areas, while chloromethane is not reliable due to its wide use as industrial chemical.
TL;DR: In this paper, seasonal elemental carbon (EC) and organic carbon (OC) concentration levels in PM2.5 samples collected in Milan (Italy) are presented and discussed, enriching the world-wide database of carbonaceous species in fine particulate matter (PM).
TL;DR: More stringent air quality standards should be adopted for coal mining areas and due consideration should be given on particle size distribution of the air-borne dust while designing control equipment, this paper concludes.
Abstract: Surface coal mining creates more air pollution problems with respect to dust than underground mining . An investigation was conducted to evaluate the characteristics of the airborne dust created by surface coal mining in the Jharia Coalfield. Work zone air quality monitoring was conducted at six locations, and ambient air quality monitoring was conducted at five locations, for a period of 1 year. Total suspended particulate matter (TSP) concentration was found to be as high as 3,723 μg/m3, respirable particulate matter (PM10) 780 μg/m3, and benzene soluble matter was up to 32% in TSP in work zone air. In ambient air, the average maximum level of TSP was 837 μg/m3, PM10 170 μg/m3 and benzene soluble matter was up to 30%. Particle size analysis of TSP revealed that they were more respirable in nature and the median diameter was around 20 μm. Work zone air was found to have higher levels of TSP, PM10 and benzene soluble materials than ambient air. Variations in weight percentages for different size particles are discussed on the basis of mining activities. Anionic concentration in TSP was also determined. This paper concludes that more stringent air quality standards should be adopted for coal mining areas and due consideration should be given on particle size distribution of the air-borne dust while designing control equipment.
TL;DR: In this article, the spectral mass-specific absorption and scattering coefficients for terrigenous mineral-rich particulate assemblages suspended in seawater were determined from laboratory measurements, and the spectral behavior varied from nearly flat spectra to the spectral dependency,l2g with a slope g as high as,1.3 for the sample with the largest contribution of small particles.
Abstract: From laboratory measurements, we determined the spectral mass-specific absorption, a �(l), and scattering, b �(l), coefficients for terrigenous mineral-rich particulate assemblages suspended in seawater. The samples were derived mostly from surface soils in different locations and consisted of small particles (,10 mm). Both a �(l) and b �(l) showed large variability associated with variations in particle size distribution (PSD) and origin of samples. Variations in a �(l) produced by changes in PSD are consistent with the package effect, in that samples with a higher percentage of small-sized particles have higher a �(l). The variability among the samples is also associated with composition of particulate matter. For example, a �(l) at blue wavelengths varied from ,0.05 m2 g21 for organic-dominated soil dust to ,0.1–0.5 m2 g21 for mineral-dominated samples. The effects of particulate composition are reflected in a broad range of imaginary refractive index of particles, which in the blue can exceed 0.2–0.3 for mineral-dominated samples rich in iron oxides. The patterns of the variability in the scattering coefficient among the samples are quite intricate because of the effects of PSD and composition. In general, b �(l) ranged from about 0.5 to 1.5 m2 g21, and the spectral behavior varied from nearly flat spectra to the spectral dependency ,l2g with a slope g as high as ,1.3 for the sample with the largest contribution of small particles. One of the greatest needs of ocean optics research is to improve knowledge and understanding of the absorption and scattering properties of suspended particulate matter at the level of detail that goes beyond the traditional description in terms of a few broadly defined bulk particulate categories, such as phytoplankton and nonphytoplankton (detrital) particles. Seawater is a complex optical medium and each of these broadly defined constituent categories includes in reality a great variety of particle types with different sizes, shapes, refractive indices, and, therefore, optical properties. Consequently, the same amounts of phytoplankton or nonphytoplankton particles parameterized in terms of bulk pigment concentration or bulk particle mass concentration in water can produce differences in the inherent optical properties (IOPs) characterizing absorption and scattering of light. This optical variability represents a major challenge that must be addressed by detailed studies of a comprehensive suite of properties of various particle types, such as different plankton groups and species, different types of other biogenic particles, different mineral species and natural mixtures of mineral species, as well as mixed organic– inorganic particle types and assemblages. The approach in which seawater is described as an optical medium consisting of a relatively large but manageable number of appropriately defined constituents should