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Showing papers in "Journal of The Air & Waste Management Association in 2013"


Journal ArticleDOI
TL;DR: Although the number of surface spills was minimal, the analysis provides scientific evidence that benzene can contaminate groundwater sources following surface spills at active well sites and demonstrates that surface spills are an important route of potential groundwater contamination from hydraulic fracturing activities and should be a focus of programs to protect groundwater.
Abstract: Concerns have arisen among the public regarding the potential for drinking-water contamination from the migration of methane gas and hazardous chemicals associated with hydraulic fracturing and horizontal drilling. However, little attention has been paid to the potential for groundwater contamination resulting from surface spills from storage and production facilities at active well sites. We performed a search for publically available data regarding groundwater contamination from spills at U.S. drilling sites. The Colorado Oil and Gas Conservation Commission (COGCC) database was selected for further analysis because it was the most detailed. The majority of spills were in Weld County, Colorado, which has the highest density of wells that used hydraulic fracturing for completion, many producing both methane gas and crude oil. We analyzed publically available data reported by operators to the COGCC regarding surface spills that impacted groundwater. From July 2010 to July 2011, we noted 77 reported surface...

158 citations


Journal ArticleDOI
TL;DR: It is argued that dedicated research is required on nonexhaust emissions and dispersion to urban areas from both an air quality and a public health perspective and the implicated message to regulators and policy makers is that road transport emissions continue to be an issue for health and air quality, despite the encouraging rapid decrease of tailpipe exhaust emissions.
Abstract: Road transport emissions are a major contributor to ambient particulate matter concentrations and have been associated with adverse health effects. Therefore, these emissions are targeted through increasingly stringent European emission standards. These policies succeed in reducing exhaust emissions, but do not address "nonexhaust" emissions from brake wear, tire wear, road wear, and suspension in air of road dust.Is this a problem? To what extent do nonexhaust emissions contribute to ambient concentrations of PM10 or PM2.5? In the near future, wear emissions may dominate the remaining traffic-related PM10 emissions in Europe, mostly due to the steep decrease in PM exhaust emissions. This underlines the need to determine the relevance of the wear emissions as a contribution to the existing ambient PM concentrations, and the need to assess the health risks related to wear particles, which has not yet received much attention. During a workshop in 2011, available knowledge was reported and evaluated so as to draw conclusions on the relevance of traffic-related wear emissions for air quality policy development. On the basis of available evidence, which is briefly presented in this paper, it was concluded that nonexhaust emissions and in particular suspension in air of road dust are major contributors to exceedances at street locations of the PM10 air quality standards in various European cities. Furthermore, wear-related PM emissions that contain high concentrations of metals may (despite their limited contribution to the mass of nonexhaust emissions) cause significant health risks for the population, especially those living near intensely trafficked locations. To quantify the existing health risks, targeted research is required on wear emissions, their dispersion in urban areas, population exposure, and its effects on health. Such information will be crucial for environmental policymakers as an input for discussions on the need to develop control strategies.Road transport particulate matter (PM) emissions are associated with adverse health effects. Stringent policies succeed in reducing the exhaust PM emissions, but do not address "nonexhaust" emissions from brake wear, tire wear, road wear, and suspension in air of road dust. In the near future the nonexhaust emissions will dominate the road transport PM emissions. Based on the limited available evidence, it is argued that dedicated research is required on nonexhaust emissions and dispersion to urban areas from both an air quality and a public health perspective. The implicated message to regulators and policy makers is that road transport emissions continue to be an issue for health and air quality, despite the encouraging rapid decrease of tailpipe exhaust emissions.Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association. © 2013 Copyright 2013 A&WMA.

140 citations


Journal ArticleDOI
TL;DR: The overall study of the methodological approaches estimating particle infiltration indoors suggests that dynamic models provide a more complete and realistic picture of ambient particles infiltration indoors, whereas the use of specific PM constituents to act as surrogates of indoor particles of outdoor origin seems also a promising new methodology.
Abstract: Recent toxicological results highlight the importance of separating exposure to indoor- and outdoor-generated particles, due to their different physicochemical and toxicological properties. In this framework, a number of studies have attempted to estimate the relative contribution of particles of indoor and outdoor origins to indoor concentrations, using either statistical analysis of indoor and outdoor concentration time-series or mass balance equations. The aim of this work is to review and compare the methodologies developed in order to determine the ambient particle infiltration factor (F(INF)) (i.e., the fraction of ambient particles that enter indoors and remains suspended). The different approaches are grouped into four categories according to their methodological principles: (1) steady-state assumption using the steady-state form of the mass balance equation; (2) dynamic solution of the mass balance equation using complex statistical techniques; (3) experimental studies using conditions that simplify model calculations (e.g., decreasing the number of unknowns); and (4) infiltration surrogates using a particulate matter (PM) constituent with no indoor sources to act as surrogate of indoor PM of outdoor origin. Examination of the various methodologies and results reveals that estimating infiltration parameters is still challenging. The main difficulty lies in the separate calculation of penetration efficiency (P) and deposition rate (k). The values for these two parameters that are reported in the literature vary significantly. Deposition rate presents the widest range of values, both between studies and size fractions. Penetration efficiency seems to be more accurately calculated through the application of dynamic models. Overall, estimates of the infiltration factor generated using dynamic models and infiltration surrogates show good agreement. This is a strong argument in favor of the latter methodology, which is simple and easy to apply when chemical speciation data are available.

125 citations


Journal ArticleDOI
TL;DR: This paper presents an examination of four different approaches to capture the environmental impacts of vehicular operations on a 10-mile stretch of Interstate 4 (I-4), an urban limited-access highway in Orlando, FL, and demonstrates that obtaining precise and comprehensive operating mode distributions on a second-by-second basis provides more accurate emission estimates.
Abstract: The Intergovernmental Panel on Climate Change (IPCC) estimates that baseline global GHG emissions may increase 25–90% from 2000 to 2030, with carbon dioxide (CO2) emissions growing 40–110% over the same period. On-road vehicles are a major source of CO2 emissions in all the developed countries, and in many of the developing countries in the world. Similarly, several criteria air pollutants are associated with transportation, for example, carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). Therefore, the need to accurately quantify transportation-related emissions from vehicles is essential. The new U.S. Environmental Protection Agency (EPA) mobile source emissions model, MOVES2010a (MOVES), can estimate vehicle emissions on a second-by-second basis, creating the opportunity to combine a microscopic traffic simulation model (such as VISSIM) with MOVES to obtain accurate results. This paper presents an examination of four different approaches to capture the environmental impacts of veh...

93 citations


Journal ArticleDOI
TL;DR: The latest U.S. Environmental Protection Agency (EPA) traffic emission model MOVES still shows significant deviations from observed emission ratios, in particular underestimation of HCHO/CO and HONO/NOx ratios, and improving the performance of MOVES may improve regional air quality modeling.
Abstract: Nitrous acid (HONO) and formaldehyde (HCHO) are important precursors for radicals and are believed to favor ozone formation significantly. Traffic emission data for both compounds are scarce and mostly outdated. A better knowledge of today's HCHO and HONO emissions related to traffic is needed to refine air quality models. Here the authors report results from continuous ambient air measurements taken at a highway junction in Houston, Texas, from July 15 to October 15, 2009. The observational data were compared with emission estimates from currently available mobile emission models (MOBILE6; MOVES [MOtor Vehicle Emission Simulator]). Observations indicated a molar carbon monoxide (CO) versus nitrogen oxides (NO(x)) ratio of 6.01 +/- 0.15 (r2 = 0.91), which is in agreement with other field studies. Both MOBILE6 and MOVES overestimate this emission ratio by 92% and 24%, respectively. For HCHO/CO, an overall slope of 3.14 +/- 0.14 g HCHO/kg CO was observed. Whereas MOBILE6 largely underestimates this ratio by 77%, MOVES calculates somewhat higher HCHO/CO ratios (1.87) than MOBILE6, but is still significantly lower than the observed ratio. MOVES shows high HCHO/CO ratios during the early morning hours due to heavy-duty diesel off-network emissions. The differences of the modeled CO/NO(x) and HCHO/CO ratios are largely due to higher NO(x) and HCHO emissions in MOVES (30% and 57%, respectively, increased from MOBILE6 for 2009), as CO emissions were about the same in both models. The observed HONO/NO(x) emission ratio is around 0.017 +/- 0.0009 kg HONO/kg NO(x) which is twice as high as in MOVES. The observed NO2/NO(x) emission ratio is around 0.16 +/- 0.01 kg NO2/kg NO(x), which is a bit more than 50% higher than in MOVES. MOVES overestimates the CO/CO2 emission ratio by a factor of 3 compared with the observations, which is 0.0033 +/- 0.0002 kg CO/kg CO2. This as well as CO/NO(x) overestimation is coming from light-duty gasoline vehicles.

71 citations


Journal ArticleDOI
TL;DR: How early warnings given by vigilant scientists highlighted the dangers of ODS and calls for action and boycotts by concerned citizens 35 years ago and regulatory actions taken by governments worldwide 25 years ago successfully phased out ODSs and avoided global catastrophe are explained.
Abstract: In 1974, Mario Molina and F. Sherwood Rowland warned that chlorofluorocarbons (CFCs) could destroy the stratospheric ozone layer that protects Earth from harmful ultraviolet radiation. In the decade after, scientists documented the buildup and long lifetime of CFCs in the atmosphere; found the proof that CFCs chemically decomposed in the stratosphere and catalyzed the depletion of ozone; quantified the adverse effects; and motivated the public and policymakers to take action. In 1987, 24 nations plus the European Community signed the Montreal Protocol. Today, 25 years after the Montreal Protocol was agreed, every United Nations state is a party (universal ratification of 196 governments); all parties are in compliance with the stringent controls; 98% of almost 100 ozone-depleting chemicals have been phased out worldwide; and the stratospheric ozone layer is on its way to recovery by 2065. A growing coalition of nations supports using the Montreal Protocol to phase down hydrofluorocarbons, which are ozone ...

66 citations


Journal ArticleDOI
TL;DR: The observed response of O3 to NOx and VOC emissions in the Southeast implies that continuing reductions of precursor emissions, probably achieved through vehicle fleet turnover and emission control measures, will be needed to attain the National Ambient Air Quality Standard for O3.
Abstract: The SEARCH study began in mid 1998 with a focus on particulate matter and gases in the southeastern United States. Eight monitoring sites, comprising four urban/nonurban pairs, are located inland and along the coast of the Gulf of Mexico. Downward trends in ambient carbon monoxide (CO), sulfur dioxide (SO2), and oxidized nitrogen species (NOy) concentrations averaged 1.2 ± 0.4 to 9.7 ± 1.8% per year from 1999 to 2010, qualitatively proportional to decreases of 4.7 to 7.9% per year in anthropogenic emissions of CO, SO2, and oxides of nitrogen (NOx) in the SEARCH region. Downward trends in mean annual sulfate (SO4) concentrations ranged from 3.7 ± 1.1 to 6.2 ± 1.1% per year, approximately linear with, but not 1:1 proportional to, the 7.9 ± 1.1% per year reduction in SO2 emissions from 1999 to 2010. The 95th percentile of the March–October peak daily 8-hr ozone (O3) concentrations decreased by 1.1 ± 0.4 to 2.4 ± 0.6 ppbv per year (1.5 ± 0.6 to 3.1 ± 0.8% per year); O3 precursor emissions of NOx and volatile ...

66 citations


Journal ArticleDOI
TL;DR: This study demonstrated that after-treatments, including diesel particulate filters (DPF), diesel oxidation catalysts (DOC), and selective catalytic reduction (SCR), significantly reduce the emissions of PAHs from heavy-duty diesel engines.
Abstract: In total, 24 polycyclic aromatic hydrocarbons (PAHs) in both gas and particle phases and 35 nitro-PAHs in particle phase were analyzed in the exhaust from heavy-duty diesel vehicles equipped with after-treatment for particulate matter (PM) and NOX control. The test vehicles were carried out using a chassis dynamometer under highway cruise, transient Urban Dynamometer Driving Schedule (UDDS), and idle operation. The after-treatment efficiently abated more than 90% of the total PAHs. Indeed, the particle-bound PAHs were reduced by >99%, and the gaseous PAHs were removed at various extents depending on the type of after-treatment and the test cycles. The PAHs in gas phase dominated the total PAH (gas + particle phases) emissions for all the test vehicles and for all cycles; that is, 99% of the two-ring and 98% of the three-ring and 97% of the four-ring and 95% of the carcinogenic PAHs were in the gas-phase after a diesel particle filter (DPF) and not bound to the very small amount of particulate matter left ...

63 citations


Journal ArticleDOI
TL;DR: Stoichiometric combustion with three-way catalyst is currently the best emission control technology available for compressed natural gas (CNG) transit buses to meet the stringent U.S. Environmental Protection Agency (EPA) 2010 heavy-duty engine NOX emissions standard.
Abstract: Engine and exhaust control technologies applied to compressed natural gas (CNG) transit buses have advanced from lean-burn, to lean-burn with oxidation catalyst (OxC), to stoichiometric combustion ...

58 citations


Journal ArticleDOI
TL;DR: The char produced in thermolysis of granulated scrap tyres was converted into activated carbon with textural properties similar to those of some commercial activated carbons, which could render the thermolytic treatment of scrap tyres more economically attractive.
Abstract: The char produced in the thermolysis of granulated scrap tyres has few market outlets, reducing the economic viability of the thermolytic process. This paper reports the potential of this char as a low-cost precursor of porous carbons. The tyre-derived char was demineralized in either alkaline or acidic media to reduce its ash, zinc, sulfur, and silica contents. The lowest impurity content was achieved with an HNO3/H2O treatment. The resulting demineralized char was then subjected to activation by KOH or CO2. The Brunauer-Emmett-Teller (BET)-specific surface area of the activated carbon produced by the KOH treatment was 242 m2/g, whereas that of the CO2-activated carbon was 720 m2/g. The textural properties of the latter product were similar to those of some commercial activated carbons. The use of tyre-derived char as a precursor of porous carbons could render the thermolytic treatment of scrap tyres more economically attractive. Implications: Char produced in thermolysis of granulated scrap tyres has a ...

57 citations


Journal ArticleDOI
TL;DR: Correlation and principal component analysis demonstrate that low visibility in Chengdu is influenced by high relative humidity, while in Chongqing the degrading visibility is related with high Relative humidity and pressure and low wind speed under a stable weather system.
Abstract: Visibility is a good indicator of air quality because it reflects the combined influences of atmospheric pollutants and synoptic processes. Trends in visibility and relationships with various factors in Chengdu and Chongqing, two megacities in southwest China, were analyzed using daily data from National Climatic Data Center and the Air Pollution Index (API) of the Ministry of Environmental Protection of China. Average annual visibility during the period of 1973–2010 was 8.1 ± 3.9 in Chengdu and 6.2 ± 4.3 km in Chongqing. PM10 dominates the reported primary pollutants in both cities, although concentrations have decreased from a high of 127.9 and 150 µg m3 before 2005 to 100.4 and 93.5 µg m−3 in Chengdu and Chongqing, respectively. Low average visibility and extremely high levels of PM10 were observed in winter, whereas relative humidity had irregular and weak seasonal variations. Visibility in both cities has deteriorated in comparison to the 1960s and 1970s, mostly due to the elevation of optical depth ...

Journal ArticleDOI
TL;DR: Most areas now indicate that weekend emission reductions now have little effect on ozone concentrations at most sites, similar to how control strategies that produce emission changes similar to those that occur on weekends affect ozone concentrations in areas where weekend emissions of ozone precursors are lower than on weekdays.
Abstract: A national analysis of weekday/weekend ozone (O3) differences conducted using 1997–1999 data found that many urban areas experienced at least 5% higher 8-hr maximum O3 concentrations on weekends than on weekdays even though emissions of precursors were significantly lower on weekends. This phenomenon was observed mostly in urban areas in the Northeast, Midwest, and coastal California. A similar analysis using 2008–2010 O3 data shows that this phenomenon has mostly vanished. From 1997–1999 to 2008–2010, the percentage of U.S. monitoring sites that experienced 95th percentile daily 8-hr maximum average O3 concentration on weekends that were 5% or more higher than on weekdays declined from about 35% to less than 5%. At the same time the percentage of sites that experienced higher weekday concentrations increased from 3% to about 27%. The majority (68%) of the sites, however, exhibited little sensitivity to the weekday/weekend emission changes as they had similar (±5%) O3 on weekdays and weekends. Similar tre...

Journal ArticleDOI
TL;DR: It can be concluded that the use of sewage-sludge-based activated carbons is a promising option for the capture of CO2 and an interesting application for this waste.
Abstract: In this work, sewage sludge was used as precursor in the production of activated carbon by means of chemical activation with KOH and NaOH. The sludge-based activated carbons were investigated for their gaseous adsorption characteristics using CO2 as adsorbate. Although both chemicals were effective in the development of the adsorption capacity, the best results were obtained with solid NaOH (SBAT16). Adsorption results were modeled according to the Langmuir and Freundlich models, with resulting CO2 adsorption capacities about 56 mg/g. The SBAT16 was characterized for its surface and pore characteristics using continuous volumetric nitrogen gas adsorption and mercury porosimetry. The results informed about the mesoporous character of the SBAT16 (average pore diameter of 56.5 A). The Brunauer-Emmett-Teller (BET) surface area of the SBAT16 was low (179 m2/g) in comparison with a commercial activated carbon (Airpel 10; 1020 m2/g) and was mainly composed of mesopores and macropores. On the other hand, the SBAT...

Journal ArticleDOI
TL;DR: Stable and statistically significant LE-PM2.5 associations are observed in analyses that control for available socioeconomic, demographic, and proxy smoking variables and that use robust regression procedures that are relatively resistant to influential observations.
Abstract: Changes in life expectancy (LE) across metropolitan areas in the United States have been associated with substantial differential reductions in fine particulate matter (aerodynamic diameter <25 μm; PM25) air pollution that occurred during the 1980s and 1990s It has been suggested that a single influential observation was largely responsible for the statistically significant LE-PM25 associations In this paper, the role of influential observations is further explored Stable and statistically significant LE-PM25 associations are observed in analyses that control for available socioeconomic, demographic, and proxy smoking variables and that use robust regression procedures that are relatively resistant to influential observations These associations are not dependent upon the inclusion or exclusion of any single observation Implications: These results contribute to the large and growing literature indicating that exposure to fine particulate matter air pollution has substantive adverse effects on huma

Journal ArticleDOI
TL;DR: The study suggests that secondary ammonium chloride aerosol can be a significant source of wintertime PM2.5 in an ammonia-rich environment, like the Wasatch Front airshed, if sufficient sources of atmospheric chlorine exist.
Abstract: Communities along Utah's Wasatch Front are currently developing strategies to reduce daily average PM2.5 levels to below National Ambient Air Quality Standards during wintertime persistent stable atmospheric conditions, or cold-air pools. Speciated PM2.5 data from the Wasatch Front airshed indicate that wintertime exceedances of the PM2.5 standard are mainly driven by high levels of ammonium nitrate. Stable wintertime conditions foster the formation of ammonium nitrate aerosol when sufficient sources of NOx, ammonia, and oxidative capacity exist. However, this work demonstrates that secondary ammonium chloride aerosol can also be a significant source of secondary wintertime PM2.5 if sufficient sources of atmospheric chlorine exist. Two factor analysis techniques, positive matrix factorization (PMF) and Unmix, were used to identify contributors to PM2.5 at three monitoring stations along Utah's Wasatch Front: Bountiful, Lindon, and Salt Lake City. The monitoring data included chemically speciated PM2.5 dat...

Journal ArticleDOI
TL;DR: During three separate studies involving characterization of diesel particulate matter, carbon nanotubes (CNTs) were found among diesel exhaust particles sampled onto transmission electron microscopy (TEM) grids to stimulate awareness and further discussion regarding the formation mechanisms of CNTs during diesel combustion.
Abstract: During three separate studies involving characterization of diesel particulate matter carbon nanotubes (CNTs) were found among diesel exhaust particles sampled onto transmission electron microscopy (TEM) grids. During these studies, samples were collected from three different diesel engines at normal operating conditions with or without an iron catalyst (introduced as ferrocene) in the fuel. This paper is to report the authors' observation of CNTs among diesel exhaust particles, with the intent to stimulate awareness and further discussion regarding the formation mechanisms of CNTs during diesel combustion.

Journal ArticleDOI
TL;DR: Projected reductions in NOx emissions without concurrent reductions in VOC emissions will likely cause ozone to increase during the next decade within central regions of the SoCAB compared with a flat or slightly declining trend in far downwind locations.
Abstract: This paper updates the historic trends (1980–2010) in ambient ozone and ozone precursor concentrations in the South Coast Air Basin (SoCAB) and examines the evolution of the ozone-precursor relationship in the Basin. Whereas reductions in NOx (oxide of nitrogen) emissions have decreased nitrate and PM2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) concentrations in the Basin during the past decade, ozone levels have increased at the central basin locations since about 2005 following a reversal in the decline of volatile organic compound (VOC)/NOx ratios during the previous two decades. A chemical box model was used to simulate the effects of changes in precursor concentrations on ozone formation using day-of-week–specific initial precursor concentrations that were derived from measurements and projected to 2020 based on expected emission reductions from 2005 (−10% VOC and −50% NOx). Results show that peak ozone formation rates in 2020 will increase on weekdays by a factor of 3 relative to 20...

Journal ArticleDOI
TL;DR: Particulate loading was higher on weekdays than on weekends (by a factor of about 1.5) in all but the marine site-class, which suggests that traffic emission is not the principal source of the Particulate Matter (PM).
Abstract: Size segregated suspended particulate matter (PM2.5 and PM2.5-10) were collected using Gent low-volume air sampler at four different receptor site-classes in Lagos Mega City, Nigeria. The particulate mass loading was quantified and the concentration was analyzed to examine the pattern and variation from one receptor site-class to another. The PM2.5/PM10 ratio varied among the site-classes with the residential and marine sites having the least and highest ratio of 0.31 +/- 0.13 and 0.49 +/- 0.17 respectively. Particulate loading was higher on weekdays than on weekends (by a factor of about 1.5) in all but the marine site-class.The mean PM2.5/PM10 ratio is 0.41 +/- 0.15, which suggests that traffic emission is not the principal source of the Particulate Matter (PM). The INAA assay of the particulates detected ten elements: As, Br, Ce, K, La, Mo, Na, Sb, Sm and Zn. Except for Br, Mo and Sb, the detected elements were more pronounced in the coarse-fractioned filter Principal Component Factor Analysis (PCFA) of the detected elements identified some common sources (traffic-related, traffic emission, sea-salt and industrial emission) for both PM fractions at the four receptor site-classes.

Journal ArticleDOI
TL;DR: The turbulent scrubber is more competent for scrubbing particulate matter, in particular PM2.5, than other higher energy or conventional scrubbers, and is comparable to other wet scrubbers of its kind for the amount of energy spent.
Abstract: A turbulent wet scrubber was designed and developed to scrub particulate matter (PM) at micrometer and submicrometer levels from the effluent gas stream of an industrial coal furnace. Experiments were conducted to estimate the particle removal efficiency of the turbulent scrubber with different gas flow rates and liquid heads above the nozzle. Particles larger than 1 µm were removed very efficiently, at nearly 100%, depending upon the flow rate, the concentration of the dust-laden air stream, and the water level in the reservoir. Particles smaller than 1 µm were also removed to a greater extent at higher gas flow rates and for greater liquid heads. Pressure-drop studies were also carried out to estimate the energy consumed by the scrubber for the entire range of particle sizes distributed in the carrier gas. A maximum pressure drop of 217 mm H2O was observed for a liquid head of 36 cm and a gas flow rate of 7 m3/min. The number of transfer units (NTU) analysis for the efficiencies achieved by the turbulen...

Journal ArticleDOI
TL;DR: Day-to-day variability in the fine particle OM/OC ratio is quite large, suggesting that using a fixed OM/ OC value in PM mass closure calculations, even one that changes seasonally, may be insufficient to achieve accurate mass closure on individual days.
Abstract: Understanding the organic matter/organic carbon (OM/OC) ratio in ambient particulate matter (PM) is critical to achieve mass closure in routine PM measurements, to assess the sources of and the degree of chemical processing organic aerosol particles have undergone, and to relate ambient pollutant concentrations to health effects. Of particular interest is how the OM/OC ratio varies in the urban environment, where strong spatial and temporal gradients in source emissions are common. We provide results of near-roadway high-time-resolution PM1 OM concentration and OM/OC ratio observations during January 2008 at Fyfe Elementary School in Las Vegas, NV, 18 m from the U.S. 95 freeway soundwall, measured with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS). The average OM/OC ratio was 1.54 (+/- 0.20 standard deviation), typical of environments with a low amount of secondary aerosol formation. The 2-min average OM/OC ratios varied between 1.17 and 2.67, and daily average OM/OC ratios varied between 1.44 and 1.73. The ratios were highest during periods of low OM concentrations and generally low during periods of high OM concentrations. OM/OC ratios were low (1.52 +/- 0.14, on average) during the morning rush hour (average OM = 2.4 microg/m3), when vehicular emissions dominate this near-road measurement site. The ratios were slightly lower (1.46 +/- 0.10) in the evening (average OM = 6.3 microg/m3), when a combination of vehicular and fresh residential biomass burning emissions was typically present during times with temperature inversions. The hourly averaged OM/OC ratio peaked at 1.66 at midday. OM concentrations were similar regardless of whether the monitoring site was downwind or upwind of the adjacent freeway throughout the day, though they were higher during stagnant conditions (wind speed < 0.5 m/sec). The OM/OC ratio generally varied more with time of day than with wind direction and speed.

Journal ArticleDOI
TL;DR: PM10 is the most important pollutant in Chinese cities, especially after the national sulfur dioxide (SO2) controls during the 11th Five Year Plan (FYP; 2006–2010), and more pollutants should be included in the API system to fully reflect the air quality status and guide future air pollution controls in Chinese Cities.
Abstract: This study gathered and processed the available air quality daily reports in 86 cities throughout China in 2001–2011. Urban air quality was assessed in terms of the evolution of the key pollutants, the pollution level, and the PM10 (particulate matter with an aerodynamic diameter <10 μm) concentrations. The authors conclude that PM10 is the most important pollutant in Chinese cities, especially after the national sulfur dioxide (SO2) controls during the 11th Five Year Plan (FYP; 2006–2010). A notable advance was the reduction of extremely heavily polluted days with air pollution index (API) above 150 from 7% in 2001 to 1% in 2011 in the all-city average. In addition, the average API-derived PM10 concentrations continually decreased during the past 11 yr. Additionally, the pollution pattern of “more severe from south to north” in China became less obvious due to the decline of PM10 concentrations in the northern cities and the more obvious regional characteristics of air pollution. Nevertheless, more pollu...

Journal ArticleDOI
TL;DR: In this article, the effects of mechanical activation on the structural changes of CRT funnel glass were investigated using X-ray diffraction (XRD), particle size analysis, specific surface area (SSA), and a scanning electron microscope (SEM).
Abstract: In the disposal of electronic waste, cathode ray tube (CRT) funnel glass remains an urgent environmental problem because of its high lead content. This research developed mechanical activation as a pretreatment process, and it proved to be an effective method for extracting lead from CRT funnel glass. The effects of mechanical activation on the structural changes of CRT funnel glass were investigated using X-ray diffraction (XRD), particle size analysis, specific surface area (SSA), and a scanning electron microscope (SEM). Nitric acid leaching behaviors of the activated CRT funnel glass were studied by varying several parameters: leaching time, liquid-to-solid ratio, acid concentration, and heating temperature, as well as various conditions of activation. The lead recovery rate was observed to increase rapidly, particularly with increases in activation time and leaching temperature, but to vary relatively less under other experimental parameters. Under the optimal leaching conditions, the lead recovery r...

Journal ArticleDOI
TL;DR: The Southeastern Aerosol Research and Characterization (SEARCH) study, which has been in continuous operation from 1999 to 2012, was implemented to investigate regional and urban air pollution in the southeastern United States.
Abstract: The Southeastern Aerosol Research and Characterization (SEARCH) study, which has been in continuous operation from 1999 to 2012, was implemented to investigate regional and urban air pollution in the southeastern United States. With complementary data from other networks, the SEARCH measurements provide key knowledge about long-term urban/nonurban pollution contrasts and regional climatology affecting inland locations and sites along the Gulf of Mexico coastline. Analytical approaches ranging from comparisons of mean concentrations to the application of air mass trajectories and principal component analysis provide insight into local and area-wide pollution. Gases (carbon monoxide, sulfur dioxide, nitrogen oxides, ozone, and ammonia), fine particle mass concentration, and fine particle species concentrations (including sulfate, elementary carbon, and organic carbon) are affected by a combination of regional conditions and local emission sources. Urban concentrations in excess of regional baselines and int...

Journal ArticleDOI
TL;DR: The results showed that source-separated urine underwent rapid urea-hydrolysis (ureolysis) at temperatures between 34–40oC, stale/fresh urine ratios greater than 40%, and/or with slight fecal cross-contamination, and an enhanced ureolysis process can attenuate the odor emissions.
Abstract: Source-separating urine from other domestic wastewaters promotes a more sustainable municipal wastewater treatment system. This study investigated the feasibility and potential issues of applying a urine source-separation system in tropical urban settings. The results showed that source-separated urine underwent rapid urea-hydrolysis (ureolysis) at temperatures between 34–40oC, stale/fresh urine ratios greater than 40%, and/or with slight fecal cross-contamination. Undiluted (or low-diluted) urine favored ureolysis; this can be monitored by measuring conductivity as a reliable and efficient indicator. The optimized parameters demonstrated that an effective urine source-separation system is achievable in tropical urban areas. On the other hand, the initial release of CO2 and NH3 led to an elevated pressure in the headspace of the collection reservoir, which then dropped to a negative value, primarily due to oxygen depletion by the microbial activity in the gradually alkalized urine. Another potential odor ...

Journal ArticleDOI
TL;DR: The results suggest that reductions in traffic volumes as well as improvements in engine design and the installation of exhaust gas treatment systems may have improved air quality.
Abstract: In Tokyo, the annual average suspended particulate matter (SPM) and PM2.5 concentrations have decreased in the past two decades. The present study quantitatively evaluated these decreasing trends using data from air-pollution monitoring stations. Annual SPM and PM2.5 levels at 83 monitoring stations and hourly SPM and PM2.5 levels at four monitoring stations in Tokyo, operated by the Tokyo Metropolitan Government, were used for analysis, together with levels of co-pollutants and meteorological conditions. Traffic volume in Tokyo was calculated from the total traveling distance of vehicles as reported by the Ministry of Land, Infrastructure, Transport, and Tourism. High positive correlations between SPM levels and nitrogen oxide levels, sulfur dioxide levels, and traffic volume were determined. The annual average SPM concentration declined by 62.6% from 59.4 µg/m3 in 1994 to 22.2 µg/m3 in 2010, and PM2.5 concentration also declined by 49.8% from 29.3 µg/m3 in 2001 to 14.7 µg/m3 in 2010. Likewise, the frequ...

Journal ArticleDOI
TL;DR: The results of this study indicate that the artificial neural network is an effective method for PM10 pollution modeling, and the Intake Fraction model provides a rapid population risk estimate for pollutant emission reduction strategies and policies.
Abstract: Primary fine particulate matters with a diameter of less than 10 µm (PM10) are important air emissions causing human health damage. PM10 concentration forecast is important and necessary to perform in order to assess the impact of air on the health of living beings. To better understand the PM10 pollution health risk in Taiyuan City, China, this paper forecasted the temporal and spatial distribution of PM10 yearly average concentration, using Back Propagation Artificial Neural Network (BPANN) model with various air quality parameters. The predicted results of the models were consistent with the observations with a correlation coefficient of 0.72. The PM10 yearly average concentrations combined with the population data from 2002 to 2008 were given into the Intake Fraction (IF) model to calculate the IFs, which are defined as the integrated incremental intake of a pollutant released from a source category or a region over all exposed individuals. The results in this study are only for main stationary source...

Journal ArticleDOI
TL;DR: The results of black carbon concentrations in these areas indicate source contributions from local sources such as forest fire, biomass burning, and vehicle emissions, which indicates pollution occurring in Bandung and Jakarta is more intense than in Yogyakarta.
Abstract: Samples of airborne particulate matter were collected at several cities in Indonesia: Bandung, Jakarta, Palangka Raya, Serpong, and Yogyakarta, from January through December 2011. The samples were collected once a week using a Gent stacked filter unit sampler in two size fractions of 2.5 µm (fine, PM2.5) and 2.5 to 10 µm (coarse, PM2.5–10). Black carbon was measured using an EEL smoke stain reflectometer. The average of PM2.5 during the sampling period for Bandung, Jakarta, Palangka Raya, Serpong, and Yogyakarta sites was 18.35, 16.50, 7.74, 16.68, and 8.78 µg/m3, respectively. The average of BC for Bandung, Jakarta, Palangka Raya, Serpong and Yogyakarta was 3.05, 3.37, 3.19, 2.51, and 2.20 μg/m3, respectively. The ratio of the 24-hr BC concentration compared to the PM2.5 concentrations showed that BC comprises about 17–45% of the fine particulate matter collected at all sites. The average percentage of BC in PM2.5 concentrations in Bandung, Jakarta, Palangka Raya, Serpong, and Yogyakarta was 18, 22, 45, ...

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TL;DR: Improved retrievals can be used to fill in the gaps between surface sites and validate air quality models that are used for air quality forecasts and epidemiological studies, and improve correlations between PM retrieved from satellite observations and PM from surface measurements in areas where the correlation is typically low.
Abstract: A combination of multiplatform satellite observations and statistical data analysis are used to improve the correlation between estimates of PM2.5 (particulate mass with aerodynamic diameter less that 2.5 microm) retrieved from satellite observations and ground-level measured PM2.5. Accurate measurements of PM2.5 can be used to assess the impact of air pollution levels on human health and the environment and to validate air pollution models. The area under study is California's San Joaquin Valley (SJV) that has a history of poor particulate air quality. Attempts to use simple linear regressions to estimate PM2.5 from satellite-derived aerosol optical depth (AOD) have not yielded good results. The period of study for this project was from October 2004 to July 2008 for six sites in the SJV. A simple linear regression between surface-measured PM2.5 and satellite-observed AOD (from MODIS [Moderate Resolution Imaging Spectroradiometer]) yields a correlation coefficient of about 0.17 in this region. The correlation coefficient between the measured PM2.5 and that retrieved combining satellite observations in a generalized additive model (GAM) resulted in an improved correlation coefficient of 0.77. The model used combinations of MODIS AOD, OMI (Ozone Monitoring Instrument) AOD, NO2 concentration, and a seasonal variable as parameters. Particularly noteworthy is the fact that the PM2.5 retrieved using the GAM captures many of the PM2.5 exceedances that were not seen in the simple linear regression model.

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TL;DR: A strong positive linear relationship between the solubilization values of PAH and the polarities of the microenvironments of pyrene with SDS-TX100 mixtures has been demonstrated.
Abstract: The solubility enhancement of phenanthrene (Phe), fluoranthene (FLT), and benzo[a]pyrene (BaP) in water by the single anionic surfactant sodium dodecyl sulfate (SDS), single nonionic surfactant Triton X-100 (TX100), and mixed surfactant solution (SDS-TX100) with varying proportions and the synergism mechanism were investigated in detail. Solubilization of phenanthrene was greatly enhanced either by SDS or by TX100. The sequence of solubilization for different mixed-surfactant solutions or surfactant solutions was SDS-TX100 (1:9, liquid mass ratio) > TX100 > SDS-TX100 (2:8) > SDS-TX100 (3:7) > SDS-TX100 (4:6) > SDS-TX100 (1:1) > SDS-TX100 (7:3) > SDS when the concentrations were above their critical micelle concentration (CMC). The composite surfactant SDS-TX100 (1:9) had better solubilization capacity than any single surfactant, which is attributed to the lower CMC of the mixed surfactant solution and the increase of the molar solubilization ratio (MSR) of the solution. The linear relationship between the...

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TL;DR: Characteristics of recent spatial distribution of emissions and emission contributions by vehicle category revealed that priority of vehicular emission control should be put on the eastern and southeastern coastal provinces and northern regions, and passenger cars and motorcycles require stricter control for the reduction of CO and NMVOC emissions.
Abstract: The vehicular emission trend in China was tracked for the recent period 2006–2009 based on a database of dynamic emission factors of CO, nonmethane volatile organic compounds (NMVOC), NOx, PM10, CO2, CH4, and N2O for all categories of on-road motor vehicles in China, which was developed at the provincial level using the COPERT 4 model, to account for the effects of rapid advances in engine technologies, implementation of improved emission standards, emission deterioration due to mileage, and fuel quality improvement. Results show that growth rates of CO and NMVOC emissions slowed down, but NOx and PM10 emissions continued rising rapidly for the period 2006–2009. Moreover, CO2, CH4, and N2O emissions in 2009 almost doubled compared to those in 2005. Characteristics of recent spatial distribution of emissions and emission contributions by vehicle category revealed that priority of vehicular emission control should be put on the eastern and southeastern coastal provinces and northern regions, and passenger c...