Search

Abstract Using waste paper as fuel for domestic heating is a beneficial recycling option for small island developing states where there are lacks of resources for energy and waste treatment. However, there are concerns about the impact of air pollutants emitted from the burning of the self-made paper briquettes as household air pollution is recognised as the greatest environmental risk for human. In this study, combustion tests were carried out for paper briquettes made in one Pacific island and three commercial fuels in Australia including wood briquettes, kindling firewood and coal briquettes in order to: 1) characterise the emissions of three criteria air pollutants including particulate matters, CO and NO x including their emission factors (EF) from the tested fuels; and 2) compare the EFs among the tested fuels and with others reported in the literature. The results showed that waste paper briquettes burned quickly and generated high temperature but the heat value is relatively low. Paper briquettes and coal briquettes produced higher CO concentration than the others while paper briquettes generated the highest NO x level. Only PM 2.5 concentration emitted from paper briquettes was similar to kindling firewood and lower than wood briquettes. Burning of paper briquettes and wood briquettes produced particulate matter with large average count median diameter (72 and 68 nm) than coal briquette and kindling firewood (45 and 51 nm). The EFs for CO, NO x and PM 2.5 of paper briquettes were within the range of EFs reported in this study as well as in the literature. Overall, the results suggested that using paper briquettes as fuel for domestic heating will not likely to generate higher level of three major air pollutants compared to other traditional fuels. Highlights • The first attempt to report emission of key air pollutants from waste paper briquettes. • Burning of paper briquettes emitted relatively high CO and NO x concentration. • Burning of paper briquettes emitted PM with large average particle size. • Waste paper could be recycled as briquettes for domestic use like other common fuels. [ABSTRACT FROM AUTHOR]

Biomass burning is a significant source of trace gases and aerosols to the atmosphere, and the evolution of these species depends acutely on where they are injected into the atmosphere. GEOS-Chem is a chemical transport model driven by assimilated meteorological data that is used to probe a variety of scientific questions related to atmospheric composition, including the role of biomass burning. This paper presents the development and implementation of a new global biomass burning emissions injection scheme in the GEOS-Chem model. The new injection scheme is based on monthly gridded Multi-angle Imaging SpectroRadiometer (MISR) global plume-height stereoscopic observations in 2008. To provide specific examples of the impact of the model updates, we compare the output from simulations with and without the new MISR-based injection height scheme to several sets of observations from regions with active fires. Our comparisons with Arctic Research on the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) aircraft observations show that the updated injection height scheme can improve the ability of the model to simulate the vertical distribution of peroxyacetyl nitrate (PAN) and carbon monoxide (CO) over North American boreal regions in summer. We also compare a simulation for October 2010 and 2011 to vertical profiles of CO over the Amazon Basin. When coupled with larger emission factors for CO, a simulation that includes the new injection scheme also better matches selected observations in this region. Finally, the improved injection height improves the simulation of monthly mean surface CO over California during July 2008, a period with large fires. [ABSTRACT FROM AUTHOR]

Context. Long gamma-ray bursts (GRBs) can potentially be used as a tool to study star formation and recent gas accretion onto galaxies. However, the information about gas properties of GRB hosts is scarce. In particular, very few carbon monoxide (CO) line detections of individual GRB hosts have been reported. It has also been suggested that GRB hosts have lower molecular gas masses than expected from their star formation rates (SFRs). Aims. The objectives of this paper are to analyse molecular gas properties of the first substantial sample of GRB hosts and test whether they are deficient in molecular gas. Methods. We obtained CO(2-1) observations of seven GRB hosts with the APEX and IRAM 30 m telescopes. We analysed these data together with all other hosts with previous CO observations. From these observations we calculated the molecular gas masses of these galaxies and compared them with the expected values based on their SFRs and metallicities. Reults. We obtained detections for 3 GRB hosts (980425, 080207, and 111005A) and upper limits for the remaining 4 (031203, 060505, 060814, and 100316D). In our entire sample of 12 CO-observed GRB hosts, 3 are clearly deficient in molecular gas, even taking into account their metallicity (980425, 060814, and 080517). Four others are close to the best-fit line for other star-forming galaxies on the SFR-MH2 plot (051022, 060505, 080207, and 100316D). One host is clearly molecule rich (111005A). Finally, the data for 4 GRB hosts are not deep enough to judge whether they are molecule deficient (000418, 030329, 031203, and 090423). The median value of the molecular gas depletion time, MH2/SFR, of GRB hosts is ∼0.3 dex below that of other star-forming galaxies, but this result has low statistical significance. A Kolmogorov–Smirnov test performed on MH2/SFR shows an only ∼2σ difference between GRB hosts and other galaxies. This difference can partly be explained by metallicity effects, since the significance decreases to ∼1σ for MH2/SFR versus metallicity. Conclusions. We found that any molecular gas deficiency of GRB hosts has low statistical significance and that it can be attributed to their lower metallicities; and thus the sample of GRB hosts has molecular properties that are consistent with those of other galaxies, and they can be treated as representative star-forming galaxies. However, the molecular gas deficiency can be strong for GRB hosts if they exhibit higher excitations and/or a lower CO-to-H2 conversion factor than we assume, which would lead to lower molecular gas masses than we derive. Given the concentration of atomic gas recently found close to GRB and supernova sites, indicating recent gas inflow, our results about the weak molecular deficiency imply that such an inflow does not enhance the SFRs significantly, or that atomic gas converts efficiently into the molecular phase, which fuels star formation. Only if the analysis of a larger GRB host sample reveals molecular deficiency (especially close to the GRB position) would this support the hypothesis of star formation that is directly fuelled by atomic gas. [ABSTRACT FROM AUTHOR]

The paper presents the temporal variations of surface ozone (O) and its precursors (oxides of nitrogen (NO), carbon monoxide (CO), methane (CH) and non-methane hydrocarbons (NMHCs)) along with particulate matter (PM and PM) and their relationship with meteorology during January 2012 to December 2014 at an urban site of Delhi, India. The mean mixing ratio of surface O, NO, CO, CH and NMHCs were 29.5 ± 7.3 ppb, 34.7 ± 11.2 ppb, 1.82 ± 0.52 ppm, 3.07 ± 0.37 ppm and 0.53 ± 0.17 ppm, respectively. This study also comprises an analysis of the relation between UV irradiance and surface O. A relationship between the total oxidant concentrations (OX) and NO has been used to identify the regional background O values and the local levels of primary pollution. An attempt has been made to identify the existence of NO or NMHC sensitive regime by charting out relationships between O, NO and NMHCs. The respective high pollution periods of surface O and PM differ on a seasonal timescale. Linear regression analysis has been used to quantify the negative influence of the chemical constituents of PM (elemental carbon, NO , SO ) on O values. Statistical validation using bivariate correlation analysis, multiple linear regression (MLR) analysis and principal component analysis (PCA) strongly describes the intricate relationships among the aforesaid variables and meteorology. Potential Source Contribution Function (PSCF) and Concentration Weighted Trajectory (CWT) analysis indicated upper Indo-Gangetic Plain (IGP) as a significant source region of O precursor gases contributing for O values at the study site. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to investigate and quantify the impact of delivery restrictions on costs and environmental performance for a distribution operation. Design/methodology/approach – Data were gathered from a company and several scenarios with varying delivery restrictions were investigated. Findings – The results show significant reductions in cost and environmental impacts are achieved when restrictions are relaxed. However, the research also highlighted the importance of adopting a supply chain (SC) approach to the removal of restrictions and the need for public/private sector cooperation. Research limitations/implications – The case study is based on one company only. However, the company performs many trips each day to many different customers. Practical implications – The paper provides insight into the scope for change in the SC decision-making processes in order to reduce environmental impacts (and identifies limitations). Originality/value – The paper is a contribution to better understanding the importance of logistics decisions and not only transport when considering urban freight problems. [ABSTRACT FROM AUTHOR]

Finding environmentally significant clusters in global supply-chain networks of goods and services has been investigated by Kagawa et al. (Soc Netw 35(3):423-438, 2013a; Econ Syst Res 25(3):265-286, 2013b; Glob Environ Chang, 2015), using the popular clustering method of nonnegative matrix factorization, which actually yields sensitive cluster assignments. Due to this sensitivity issue, there is a danger of overfitting of the results. In order to confirm the robustness of the obtained clusters, which in fact have strong implications for international climate change mitigation, especially for the US-induced Chinese clusters, we design a simulation-based experiment. Empirical findings of the proposed approach are compared with those of Kagawa et al. (Glob Environ Chang, 2015). The environmental implications are reported as well. [ABSTRACT FROM AUTHOR]

A new global reanalysis data set of atmospheric composition (AC) for the period 2003-2015 has been produced by the Copernicus Atmosphere Monitoring Service (CAMS). Satellite observations of total column (TC) carbon monoxide (CO) and aerosol optical depth (AOD), as well as several TC and profile observations of ozone, have been assimilated with the Integrated Forecasting System for Composition (C-IFS) of the European Centre for Medium-Range Weather Forecasting. Compared to the previous Monitoring Atmospheric Composition and Climate (MACC) reanalysis (MACCRA), the new CAMS interim reanalysis (CAMSiRA) is of a coarser horizontal resolution of about 110 km, compared to 80 km, but covers a longer period with the intent to be continued to present day. This paper compares CAMSiRA with MACCRA and a control run experiment (CR) without assimilation of AC retrievals. CAMSiRA has smaller biases than the CR with respect to independent observations of CO, AOD and stratospheric ozone. However, ozone at the surface could not be improved by the assimilation because of the strong impact of surface processes such as dry deposition and titration with nitrogen monoxide (NO), which were both unchanged by the assimilation. The assimilation of AOD led to a global reduction of sea salt and desert dust as well as an exaggerated increase in sulfate. Compared to MACCRA, CAMSiRA had smaller biases for AOD, surface CO and TC ozone as well as for upper stratospheric and tropospheric ozone. Finally, the temporal consistency of CAMSiRA was better than the one of MACCRA. This was achieved by using a revised emission data set as well as by applying careful selection and bias correction to the assimilated retrievals. CAMSiRA is therefore better suited than MACCRA for the study of interannual variability, as demonstrated for trends in surface CO. [ABSTRACT FROM AUTHOR]

Environmental concerns have been raised on the adverse health effects of vehicle emissions in micro-scale traffic-crowded street canyons, especially for pedestrians and residents living in near-road buildings. Viaduct design is sometimes used to improve transportation efficiency but possibly affects urban airflow and the resultant exposure risk, which have been rarely investigated so far. The personal intake fraction ( P _ IF ) is defined as the average fraction of total emissions that is inhaled by each person of a population (1 ppm = 1 × 10 −6 ), and the daily carbon monoxide (CO) pollutant exposure ( E t ) is estimated by multiplying the average concentration of a specific micro-environment within one day. As a novelty, by considering time activity patterns and breathing rates in various micro-environments for three age groups, this paper introduces IF and E t into computational fluid dynamic (CFD) simulation to quantify the impacts of street layouts (street width/building height W / H = 1, 1.5, 2), source location, viaduct settings and noise barriers on the source-exposure correlation when realistic CO sources are defined. Narrower streets experience larger P_ IF (1.51–5.21 ppm) and CO exposure, and leeward-side buildings always attain higher vehicular pollutant exposure than windward-side. Cases with a viaduct experience smaller P_IF (3.25–1.46 ppm) than cases without a viaduct ( P_IF = 5.21–2.23 ppm) if the single ground-level CO source is elevated onto the viaduct. With two CO sources (both ground-level and viaduct-level), daily CO exposure rises 2.80–3.33 times but P_IF only change slightly. Noise barriers above a viaduct raise concentration between barriers, but slightly reduce vehicular exposure in near-road buildings. Because people spend most of their time indoors, vehicular pollutant exposure within near-road buildings can be 6–9 times that at pedestrian level. Although further studies are still required to provide practical guidelines, this paper provides effective methodologies to quantify the impacts of street/viaduct configurations on human exposure for urban design purpose. [ABSTRACT FROM AUTHOR]

In this paper, environmental impacts occurred by different type of fuel used in a double-chambered crematory were analyzed and evaluated. Four kinds of fuel, which are diesel, Liquefied Petroleum Gas (LPG), electricity and biomass gas derived from gasification, were selected, whereas 60 kg of human corpse was assumed. Methodologies proposed in this paper consist of Greenhouse Gas emission, and damages to human health with ecosystem, which were analyzed by ReCipe Midpoint and Endpoint V1.05. The utilization of electricity for cremation process resulted in highest Greenhouse Gas (GHG) emission, which was 388 kgCO 2 -eq. At a same time, it was discovered high amount of GHG releasing from utilization of biomass producer gas, due to amount of fuel consumption and fuel's carbon content. It was investigated that using of diesel and LPG caused of drastic human toxicity after cremation process, by the formation of nitrogen oxide and unburnt carbon monoxide occurred from deficient combustion. Consequently, these evaluation results promoted the benefit of biomass energy utilization, in order to reduce fossil depletion and toxic emission, and it can be implied as carbon neutral concept. Likewise, if electricity will be applied as fuel for cremation, increasing the ratio of green energy in electricity production can decrease the environmental impacts. [ABSTRACT FROM AUTHOR]

This paper describes a numerical experiment to test the ability of the proposed geoCARB satellite to estimate emissions of trace gases (CO2, CH4 and CO) in the polluted urban environment of Shanghai. The meteorology over Shanghai is simulated with the Weather Research and Forecasting (WRF) model for a 9-day period in August 2010. The meteorology includes water and ice clouds. The chemistry version of WRF (WRF-Chem V3.6.1) is used to predict the chemical composition, mass density and number density of aerosol species. Spectra in the bands measured by geo-CARB are calculated, including the effects of polarisation and multiple scattering of radiation by clouds, aerosols and molecules. Instrument noise is added, and column-averaged trace-gas mole fractions are estimated from the noisy spectra using an algorithm based on that for the Greenhouse Gases Observing Satellite (GOSAT) and the Orbiting Carbon Observatory-2 (OCO-2) but adapted to geoCARB. As expected, the high aerosol loadings are challenging. However, when the retrieval algorithm is provided with regionally adjusted aerosol optical properties, as might be determined from observations of dark targets within the field of regard, the accuracies of retrieved concentrations are comparable to those reported earlier for geoCARB. Statistics of the errors in the retrieved column-averaged concentrations are used to predict the reduction in uncertainty of surface emissions possible with remotely sensed data. [ABSTRACT FROM AUTHOR]

Burning of fuels from the transport sector is one of the main sources of air pollutants emission in urban areas. In order to implement public policies concerning air quality and public health, there is a need to develop emission inventories. Measurements inside traffic tunnels can provide an evaluation of emission factors of vehicles in-use in real conditions. In this paper, we show measurements of air pollutants for a mixed vehicle fleet, heavy- and light-duty vehicles (HDVs and LDVs), in two tunnels in the metropolitan region of Sao Paulo in 2011 in order to calculate the pollutant emission factors (EFs). Measurements of carbon dioxide, carbon monoxide (CO), nitrogen oxides (NO) and particle matter (PM) were taken. High concentrations related to high-density traffic, especially during weekdays. EFs were heavily influenced by the pollutant species loads, so the total vehicle traffic and the fraction of HDV. The EF values for HDV were 3.6 and 9.2 g km, for CO and NO, respectively (5.8 and 0.3 g km for LDV). To determine EF estimates, parameters such as velocity of the air, cross-sectional area and length of the tunnel and vehicles passing at 1-h time interval were considered. [ABSTRACT FROM AUTHOR]

Tropical fires represent a highly uncertain source of atmospheric methane (CH4) because of the variability of fire emissions and the dependency of the fire CH4 emission factors (g kg-1 dry matter burned) on fuel type and combustion phase. In this paper we use new observations of CH4 and CO in the free troposphere from the Aura Tropospheric Emission Sounder (TES) satellite instrument to place constraints on the role of tropical fire emissions versus microbial production (e.g. in wetlands and livestock) during the (October) 2006 El Niño, a time of significant fire emissions from Indonesia. We first compare the global CH4 distributions from TES using the GEOS-Chem model. We find a mean bias between the observations and model of 26.3 ppb CH4 that is independent of latitude between 50° S and 80° N, consistent with previous validation studies of TES CH4 retrievals using aircraft measurements. The slope of the distribution of CH4 versus CO as observed by TES and modeled by GEOSChem is consistent (within the TES observation error) for air parcels over the Indonesian peat fires, South America, and Africa. The CH4 and CO distributions are correlated between R = 0.42 and R = 0.46, with these correlations primarily limited by the TES random error. Over Indonesia, the observed slope of 0.13 (ppb ppb-1) ±0.01, as compared to a modeled slope of 0.153 (ppb ppb-1) ±0.005 and an emission ratio used within the GEOS-Chem model of approximately 0.11 (ppb ppb-1), indicates that most of the observed methane enhancement originated from the fire. Slopes of 0.47 (ppb ppb-1) ±0.04 and 0.44 (ppb ppb-1) ±0.03 over South America and Africa show that the methane in the observed air parcels primarily came from microbial-generated emissions. Sensitivity studies using GEOS-Chem show that part of the observed correlation for the Indonesian observations and most of the observed correlations over South America and Africa are a result of transport and mixing of the fire and nearby microbial-generated emissions into the observed air parcels. Differences between observed and modeled CH4 distributions over South America and southern Africa indicate that the magnitude of the methane emissions for this time period are inconsistent with observations even if the relative distribution of fire versus biotic emissions are consistent. This study shows the potential for estimation of CH4 emissions over tropical regions using joint satellite observations of CH4 and CO. [ABSTRACT FROM AUTHOR]

A method is presented for the evaluation of the exhaust emissions of marine traffic, based on the messages provided by the Automatic Identification System (AIS), which enable the positioning of ship emissions with a high spatial resolution (typically a few tens of metres). The model also takes into account the detailed technical data of each individual vessel. The previously developed model was applicable for evaluating the emissions of NOx, SOx and CO2. This paper addresses a substantial extension of the modelling system, to allow also for the mass-based emissions of particulate matter (PM) and carbon monoxide (CO). The presented Ship Traffic Emissions Assessment Model (STEAM2) allows for the influences of accurate travel routes and ship speed, engine load, fuel sulphur content, multiengine setups, abatement methods and waves. We address in particular the modeling of the influence on the emissions of both engine load and the sulphur content of the fuel. The presented methodology can be used to evaluate the total PM emissions, and those of organic carbon, elemental carbon, ash and hydrated sulphate. We have evaluated the performance of the extended model against available experimental data on engine power, fuel consumption and the composition-resolved emissions of PM. We have also compared the annually averaged emission values with those of the corresponding EMEP inventory, As example results, the geographical distributions of the emissions of PM and CO are presented for the marine regions of the Baltic Sea surrounding the Danish Straits. [ABSTRACT FROM AUTHOR]

Significant amounts of carbon and nutrients are released to the atmosphere due to large fires in forests. Characterization of the spatial distribution and temporal variation of the intense fire emissions is crucial for assessing the atmospheric loadings of trace gases and aerosols. This paper discusses issues of the representation of forest fires in the estimation of emissions and the application to an atmospheric chemistry transport model (CTM). The potential contribution of forest fires to the deposition of bioavailable iron (Fe) into the ocean is highlighted, with a focus on mega fires in eastern Siberia. Satellite products of burned area, active fire, and land cover are used to estimate biomass burning emissions in conjunction with a biogeochemical model. Satellite-derived plume height from MISR is used for the injection height of boreal forest fire emissions. This methodology is applied to quantify fire emission rates in each three-dimensional grid location in the high latitude Northern Hemisphere (>30° N latitude) over a 5-yr period from 2001 to 2005. There is large interannual variation in forest burned area during 2001-2005 (13-49 x 10³ km² yr-1) which results in a corresponding variation in the annual emissions of carbon monoxide (CO) (14-81 Tg CO yr-1). Satellite observations of CO column from MOPITT are used to evaluate the model performance in simulating the spatial distribution and temporal variation of the fire emissions. The model results for CO enhancements due to eastern Siberian fires are in good agreement with MOPITT observations. These validation results suggest that the model using emission rates estimated in this work is able to describe the interannual changes in CO due to intense forest fires. Bioavailable iron is derived from atmospheric processing of relatively insoluble iron from desert sources by anthropogenic pollutants (mainly sulfuric acid formed from oxidation of SO2) and from direct emissions of soluble iron from combustion sources. Emission scenarios for IPCC AR5 report (Intergovernmental Panel on Climate Change; Fifth Assessment Report) suggest that anthropogenic SO2 emissions are suppressed in the future to improve air quality. In future warmer and drier climate, severe fire years such as 2003 may become more frequent in boreal regions. The fire emission rates estimated in this study are applied to the aerosol chemistry transport model to examine the relative importance of biomass burning sources of soluble iron compared to those from dust sources. The model reveals that extreme fire events contribute to a significant deposition of soluble iron (20-40%) to downwind regions over the western North Pacific Ocean, compared to the dust sources with no atmospheric processing by acidic species. These results suggest that the supply of nutrients from large forest fires plays a role as a negative biosphere-climate feedback with regards to the ocean fertilization. [ABSTRACT FROM AUTHOR]

Abstract: Vehicular emitted air pollutant concentrations were studied near three types of roadways in Austin, Texas: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway dominated by truck traffic. Air pollutants examined include carbon monoxide (CO), oxides of nitrogen (NO x ), and carbonyl species in the gas-phase. In the particle phase, ultrafine particle (UFP) concentrations (diameter < 100 nm), fine particulate matter (PM2.5, diameter < 2.5 μm) mass and carbon content and several particle-bound organics were examined. All roadways had an upwind stationary sampling location, one or two fixed downwind sample locations and a mobile monitoring platform that characterized pollutant concentrations fall-off with increased distance from the roadways. Data reported in this paper focus on UFP while other pollutants and near-roadway chemical processes are examined in a companion paper. Traffic volume, especially heavy-duty traffic, wind speed, and proximity to the road were found to be the most important factors determining UFP concentrations near the roadways. Since wind directions were not consistent during the sampling periods, distances along wind trajectories from the roadway to the sampling points were used to study the decay characteristics of UFPs. Under perpendicular wind conditions, for all studied roadway types, particle number concentrations increased dramatically moving from the upwind side to the downwind side. The elevated particle number concentrations decay exponentially with increasing distances from the roadway with sharp concentration gradients observed within 100–150 m, similar to previously reported studies. A single exponential decay curve was found to fit the data collected from all three roadways very well under perpendicular wind conditions. No consistent pattern was observed for UFPs under parallel wind conditions. However, regardless of wind conditions, particle concentrations returned to background levels within a few hundred meters of the roadway. Within measured UFP size ranges, smaller particles (6–25 nm) decayed faster than larger ones (100–300 nm). Similar decay rates were observed among UFP number, surface, and volume. [Copyright &y& Elsevier]

The importance of natural gas engines is increasing due to low CO2 emissions. To optimize these engines, a direct injection valve has been developed that works with low pressure and is triggered purely electrical. The development of this valve has been supported by numerical simulations using a coupled boundary-element-method-finite-element-method (BEM-FEM) code. This paper deals with the interaction of theoretical considerations, numerical simulations, and measurements on the realized device. In order to achieve the prescribed electromagnetic forces, numerous aspects were considered. The exciting coil, the armature, and the stator geometry is of basic interest. Several concepts have been investigated. Finally, a simple but powerful concept is realized. The simulation results have been compared to measurements on the lately constructed valve. [ABSTRACT FROM AUTHOR]

Cogeneration plants are strongly sustained by EU energy policies, one of the best beneficiary of this technology being residential buildings. This paper focus on spark ignition engine as a cogeneration application in order to supply energy for domestic consumers. Are considered two aspects of this solution: the energetic aspect and the environmental one. The energetic aspect deals with the energetic ratios, while the environmental aspect refers to the nitrogen oxide and carbon monoxide emissions. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses the effects of combustion conditions on PCDD/PCDF emissions from pulp and paper power boilers burning salt-laden wood waste. We found no correlation between PCDD/PCDF emissions and carbon monoxide emissions. A good correlation was, however, observed between PCDD/PCDF emissions and the concentration of stack polynuclear aromatic hydrocarbons (PAHs) in the absence of TDF addition. Thus, poor combustion conditions responsible for the formation of products of incomplete combustion (PICs), such as PAHs and PCDD/PCDF precursors, increase PCDD/PCDF emissions. PAH concentrations increased with higher boiler load and/or low oxygen concentrations at the boiler exit, probably because of lower available residence times and insufficient excess air. Our findings are consistent with the current understanding that high ash carbon content generally favours heterogeneous reactions leading to either de novo synthesis of PCDD/PCDFs or their direct formation from precursors. We also found that, in grate-fired boilers, a linear increase in the grate/lower furnace temperature produces an exponential decrease in PCDD/PCDF emissions. Although the extent of this effect appears to be mill-specific, particularly at low temperatures, the results indicate that increasing the combustion temperature may decrease PCDD/PCDF emissions. It must be noted, however, that there are other variables, such as elevated ESP and stack temperatures, a high hog salt content, the presence of large amounts of PICs and a high Cl/S ratio, which contribute to higher PCDD/PCDFs emissions. Therefore, higher combustion temperatures, by themselves, will not necessarily result in low PCDD/PCDFs emissions. [Copyright &y& Elsevier]

Measurement of Pollution in the Troposphere (MOPITT) is an eight-channel gas correlation radiometer selected for the Earth Observing System AM-1 platform to be launched in 1999. Its primary objectives are the measurement of tropospheric carbon monoxide (CO) and methane (CH4 ). In this paper, the sensitivities of instrument signals and CO retrieval errors to various instrument parameters, especially the gas cell pressure and temperature variations, instrument radiometric noise, and ancillary data errors (such as atmospheric temperature and water vapor profile errors), are presented and discussed. In the MOPITT pressure modulator cell pressure sensitivity study, the instrument calibration process is considered, which leads to the relaxation of previous stringent requirements on the accuracy of in-orbit cell pressure monitoring. The approach of MOPITT CO retrieval error analysis is described, and the error analysis results are compared with retrieval simulation statistics. The error analysis results indicate that tropospheric CO distributions can be retrieved with a precision of 10percent for most of the troposphere. [ABSTRACT FROM AUTHOR]

This paper presents the retrieval and validation of a self-consistent time series of carbon monoxide (CO) above Kiruna using measurements from the Kiruna Microwave Radiometer (KIMRA). The data set currently spans the years 2008-2015, and measurements are ongoing at Kiruna. The spectra are inverted using an optimal estimation method to retrieve altitude profiles of CO concentrations in the atmosphere within an average altitude range of 48-84 km. Atmospheric temperature data from the Special Sensor Microwave Imager/Sounder aboard the US Air Force meteorological satellite DMSP-F18, are used in the inversion of KIMRA spectra between January 2011 and May 2014. This KIMRA CO data set is compared with CO data from the Microwave Limb Sounder aboard the Aura satellite: there is a maximum bias for KIMRA of ~0.65 ppmv at 68 km (corresponding to 14.7% of the mean CO value at 68 km) and a maximum relative bias of 22% (0.44 ppmv) at 60 km. Standard deviations of the differences between profiles are similar in magnitude to the estimated uncertainties in the profiles. Correlations between the instruments are within 0.87 and 0.94. These numbers indicate agreement between the instruments. To expand the CO data set outside of the lifetime of DMSP-F18, another inversion setup was used that incorporates modelled temperatures from the European Centre for Medium-Range Weather Forecasts. The effect on the retrieved CO profiles when using a different temperature data set in the inversion was assessed. A comparison of the two overlapping KIMRA CO data sets shows a positive bias of <5% in the extended data set and a correlation >0.98 between the lower retrievable altitude limit and 82.5 km. The extended data set shows a larger range (≤6 %) of CO concentrations that is not explained by random error estimates. Measurements are continuing and the extended KIMRA CO time series currently spans 2008-2015, with gaps corresponding to non-operation and summer periods when CO concentrations below ~90 km drop to very low values. [ABSTRACT FROM AUTHOR]

This paper describes the second phase of an Observing System Simulation Experiment (OSSE) that utilizes the synthetic measurements from a constellation of satellites measuring atmospheric composition from geostationary (GEO) Earth orbit presented in part I of the study. Our OSSE is focused on carbon monoxide observations over North America, East Asia and Europe where most of the anthropogenic sources are located. Here we assess the impact of a potential GEO constellation on constraining northern hemisphere (NH) carbon monoxide (CO) using data assimilation. We show how cloud cover affects the GEO constellation data density with the largest cloud cover (i.e., lowest data density) occurring during Asian summer. We compare the modeled state of the atmosphere (Control Run), before CO data assimilation, with the known “true” state of the atmosphere (Nature Run) and show that our setup provides realistic atmospheric CO fields and emission budgets. Overall, the Control Run underestimates CO concentrations in the northern hemisphere, especially in areas close to CO sources. Assimilation experiments show that constraining CO close to the main anthropogenic sources significantly reduces errors in NH CO compared to the Control Run. We assess the changes in error reduction when only single satellite instruments are available as compared to the full constellation. We find large differences in how measurements for each continental scale observation system affect the hemispherical improvement in long-range transport patterns, especially due to seasonal cloud cover. A GEO constellation will provide the most efficient constraint on NH CO during winter when CO lifetime is longer and increments from data assimilation associated with source regions are advected further around the globe. [ABSTRACT FROM AUTHOR]

Abstract: This research aims to determine the overall effects that a vehicle''s short-term operating history has on its subsequent emissions, and how Vehicle Specific Power (VSP)-based vehicle emission models could be improved to account for these effects. Current VSP-based emission models, such as the U.S. EPA''s MOtor Vehicle Emission Simulator (MOVES), only predict emissions based on instantaneous vehicle activity and the corresponding VSP value; the past short-term vehicle operational activity is not taken into account (e.g., the last 10–20 s of operation). For example, instantaneous vehicle emissions could be affected by a hard acceleration vs. a deceleration event at that particular point in time. This paper attempts to determine the accuracy of VSP-based emission models, which may suffer due to the fact that the history effects are being overlooked. A number of experiments were carried out in order to determine the anomalies resulting from instantaneous estimation as opposed to taking short-term vehicle operating history into account. These experiments compare model estimates with actual emission measurements. A quantitative analysis shows that the higher power operating modes (such as modes 33, 35, 37, 38, and 40 in MOVES) had the greatest variability – sometimes in the range of 60–100% – due to the effects that vehicle operating history has on carbon monoxide (CO). Hydrocarbons (HC) in higher power operating modes also vary 40–60% depending on the driving cycle. For lower power operating modes (e.g., MOVES modes 1–30), the uncertainty for all pollutants was significantly less. It was also established that the carbon dioxide (CO2) and nitrogen oxide (NO x ) estimations conducted by MOVES were least affected by the vehicle operational history effects compared with other emissions. As such, MOVES emission results are more accurate for mild to normal driving cycles, but there is greater uncertainty for higher power driving cycles. [Copyright &y& Elsevier]

Abstract: The contribution of vehicular traffic to air pollutant concentrations is often difficult to establish. This paper utilizes both time-series and simulation models to estimate vehicle contributions to pollutant levels near roadways. The time-series model used generalized additive models (GAMs) and fitted pollutant observations to traffic counts and meteorological variables. A one year period (2004) was analyzed on a seasonal basis using hourly measurements of carbon monoxide (CO) and particulate matter less than 2.5 μm in diameter (PM2.5) monitored near a major highway in Detroit, Michigan, along with hourly traffic counts and local meteorological data. Traffic counts showed statistically significant and approximately linear relationships with CO concentrations in fall, and piecewise linear relationships in spring, summer and winter. The same period was simulated using emission and dispersion models (Motor Vehicle Emissions Factor Model/MOBILE6.2; California Line Source Dispersion Model/CALINE4). CO emissions derived from the GAM were similar, on average, to those estimated by MOBILE6.2. The same analyses for PM2.5 showed that GAM emission estimates were much higher (by 4–5 times) than the dispersion model results, and that the traffic-PM2.5 relationship varied seasonally. This analysis suggests that the simulation model performed reasonably well for CO, but it significantly underestimated PM2.5 concentrations, a likely result of underestimating PM2.5 emission factors. Comparisons between statistical and simulation models can help identify model deficiencies and improve estimates of vehicle emissions and near-road air quality. [Copyright &y& Elsevier]

Abstract: The aggressive traffic interventions and emission control measures implemented to improve air quality during the 2008 Beijing Olympic Games created a valuable case study to evaluate the effectiveness of these measures on mitigating air pollution and protecting public health. In this paper, we report the results from our field campaign in summer 2008 on the on-road emission factors of carbon monoxide, black carbon (BC) and ultrafine particles (UFP) as well as the ambient BC concentrations. The fleet average emission factors for light-duty gasoline vehicles (LDGV) showed considerable reduction in the Olympic year (2008) compared to the pre-Olympic year (2007). Our measurement of Black Carbon (BC), a primary pollutant, at different elevations at the ambient site suggests consistent decrease in BC concentrations as the height increased near the ground level, which indicates that the nearby ground level sources, probably dominated by traffic, contributed to a large portion of BC concentrations in the lower atmospheric layer in Beijing during summertime. These observations indicate that people living in near ground levels experience higher exposures than those living in higher floors in Beijing. The BC diurnal patterns on days when traffic control were in place during the Olympic Games were compared to those on non-traffic-control days in both 2007 and in 2008. These patterns strongly suggest that diesel trucks are a major source of summertime BC in Beijing. The median BC concentration on Olympic days was 3.7 μg m−3, which was dramatically lower than the value on non-traffic-control days, indicating the effectiveness of traffic control regulations in BC reduction in Beijing. [Copyright &y& Elsevier]

Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fuel used in the U.S. is consumed by military aircraft, and emissions from this source are facing increasingly stringent environmental regulations, so improved methods for quickly and accurately determining emissions from existing and new engines are needed. This paper reports results of a study to advance the methods used for detailed characterization of military aircraft emissions, and provides emission factors for two aircraft: the F-15 fighter and the C-130 cargo plane. The measurements involved outdoor ground-level sampling downstream behind operational military aircraft. This permits rapid change-out of the aircraft so that engines can be tested quickly on operational aircraft. Measurements were made at throttle settings from idle to afterburner using a simple extractive probe in the dilute exhaust. Emission factors determined using this approach agree very well with those from the traditional method of extractive sampling at the exhaust exit. Emission factors are reported for CO2, CO, NO, NO x , and more than 60 hazardous and/or reactive organic gases. Particle size, mass and composition also were measured and are being reported separately. Comparison of the emissions of nine hazardous air pollutants from these two engines with emissions from nine other aircraft engines is discussed. [Copyright &y& Elsevier]

As an alternative and renewable fuel, biodiesel can effectively reduce diesel engine emissions, especially particulate matter and dry soot. However, the biodiesel effects on emissions may vary as the source fuel changes. In this paper, the performance of five methyl esters with different sources was studied: cottonseed methyl ester (CME), soybean methyl ester (SME), rapeseed methyl ester (RME), palm oil methyl ester (PME) and waste cooking oil methyl ester (WME). Total particulate matter (PM), dry soot (DS), non-soot fraction (NSF), nitrogen oxide (NO x ), unburned hydrocarbon (HC), and carbon monoxide (CO) were investigated on a Cummins ISBe6 Euro III diesel engine and compared with a baseline diesel fuel. Results show that using different methyl esters results in large PM reductions ranging from 53% to 69%, which include the DS reduction ranging from 79% to 83%. Both oxygen content and viscosity could influence the DS emission. Higher oxygen content leads to less DS at high load while lower viscosity results in less DS at low load. NSF decreases consistently as cetane number increases except for PME. The cetane number could be responsible for the large NSF difference between different methyl esters. [Copyright &y& Elsevier]

A comprehensive air quality modeling project was carried out to simulate size and composition resolved airborne particulate matter concentrations in northern and central California using the pollutant concentration and meteorological data collected during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) from December 15, 2000 to January 7, 2001. Measured 24-h average PM2.5 concentrations during this time period exceeded 180μgm−3 at Bakersfield, making it the most severe PM2.5 air quality episode ever recorded in the United States with a rigorous measurement database to support modeling. In this paper, the UCD/CIT source-oriented air quality model is used to predict the concentrations of O3, NO, NO2, CO, elemental carbon (EC), organic compounds (OC), nitrate and PM2.5 mass concentration over a 24-day period using a horizontal resolution of 4km×4km to cover all of central California. This is the first extensive evaluation of an air quality model in central California using the fine spatial resolution appropriate for the mountain–valley topography of the region combined with the relatively long multi-week time scales associated with winter stagnation events. Fractional bias (FB) values were calculated at all sites on each day of the study to quantify model performance. The CO (FB=−0.5 to +0.3), O3 (FB=−0.5 to +0.25), NO (FB=−0.9 to −0.1) and NO2 (FB=0 to +0.4) concentrations predicted by the UCD/CIT model are in general agreement with observations at most monitoring stations throughout the Valley. The predicted PM2.5 concentrations (FB=−0.5 to +0.75) generally agree with observations at Bethel Island, Sacramento, Fresno and Bakersfield spanning the entire length of the model domain. PM2.5 concentrations are over-predicted at the remote monitoring site Angiola in the central portion of the domain. Part of the over-prediction is due to excess fugitive dust emissions. CO, NO, EC and OC were all under-predicted at Angiola, indicating possible missing combustion sources in the emission inventory. The regional nitrate (FB=−1.5 to +1.25) formation dynamics were correctly reproduced by the model simulation but imperfect wind fields cause differences between the predicted vs. measured spatial distribution of nitrate during the last several days of simulation leading to the broader range of fraction bias. Overall, the results of the current study confirm the ability of the air quality model to capture the major features of a severe particulate air pollution event in northern and central California providing a foundation for future studies on source apportionment and emissions control. [Copyright &y& Elsevier]

The Alpine stations Zugspitze, Hohenpeissenberg, Sonnblick, Jungfraujoch and Mt. Krvavec contribute to the Global Atmosphere Watch Programme (GAW) of the World Meteorological Organization (WMO). The aim of GAW is the surveillance of the large-scale chemical composition of the atmosphere. Thus, the detection of air pollutant transport from regional sources is of particular interest. In this paper, the origin of NO x (measured with a photo-converter), CO and O3 at the four Alpine GAW stations is studied by trajectory residence time statistics. Although these methods originated during the early 1980s, no comprehensive study of different atmospheric trace gases measured simultaneously at several background observatories in the Alps was conducted up to present. The main NO x source regions detected by the trajectory statistics are the northwest of Europe and the region covering East Germany, Czech Republic and southeast Poland, whereas the main CO source areas are the central, north eastern and eastern parts of Europe with some gradient from low to high latitudes. Subsiding air masses from west and southwest are relatively poor in NO x and CO. The statistics for ozone show strong seasonal effects. Near ground air masses are poor in ozone in winter but rich in ozone in summer. The main source for high ozone concentration in winter is air masses that subside from higher elevations, often enhanced by foehn effects at Hohenpeissenberg. During summer, the Mediterranean constitutes an important additional source for high ozone concentrations. Especially during winter, large differences between Hohenpeissenberg and the higher elevated stations are found. Hohenpeissenberg is frequently within the inversion, whereas the higher elevated stations are above the inversion. Jungfraujoch is the only station where the statistics detect an influence of air rich in CO and NO x from the Po Basin. [Copyright &y& Elsevier]

We have used a global version of the Regional Air Pollution Information and Simulation (RAINS) model to estimate anthropogenic emissions of the air pollution precursors sulphur dioxide (SO2), nitrogen oxides (NO x ), carbon monoxide (CO), primary carbonaceous particles of black carbon (BC), organic carbon (OC) and methane (CH4). We developed two scenarios to constrain the possible range of future emissions. As a baseline, we investigated the future emission levels that would result from the implementation of the already adopted emission control legislation in each country, based on the current national expectations of economic development. Alternatively, we explored the lowest emission levels that could be achieved with the most advanced emission control technologies that are on the market today. This paper describes data sources and our assumptions on activity data, emission factors and the penetration of pollution control measures. We estimate that, with current expectations on future economic development and with the present air quality legislation, global anthropogenic emissions of SO2 and NO x would slightly decrease between 2000 and 2030. For carbonaceous particles and CO, reductions between 20% and 35% are computed, while for CH4 an increase of about 50% is calculated. Full application of currently available emission control technologies, however, could achieve substantially lower emissions levels, with decreases up to 30% for CH4, 40% for CO and BC, and nearly 80% for SO2. [Copyright &y& Elsevier]

It is very useful for the authorities and the people to have daily easy understandable information about the levels of air pollution and the proper measures to be taken for the protection of human health. In this paper we develop an aggregate Air Quality Index (AQI) based on the combined effects of five criteria pollutants (CO, SO2, NO2, O3 and PM10) taking into account the European standards. We evaluate it for each monitoring station and for the whole area of Athens, Greece, an area with serious air pollution problems. A comparison was made with a modified version of Environmental Protection Agency/USA (USEPA) maximum value AQI model adjusted for European conditions. Hourly data of air pollutants from 4 monitoring stations, available during 1983–1999, were analysed for the development of the proposed index. The analysis reveals the Athenian population exposure reaches high levels and during last years a gradual increase of days with unhealthy conditions was detected. The proposed aggregate model estimates more effectively the exposure of citizens comparing with the modified USEPA maximum value model, because counts the impact of all the pollutants measured. Towards the informing and protection of the citizens in an urban agglomeration this model advantages as a political and administrative tool for the design of abatement strategies and effective measures of intervention. [Copyright &y& Elsevier]

Artificial neural networks are functional alternative techniques in modelling the intricate vehicular exhaust emission dispersion phenomenon. Pollutant predictions are notoriously complex when using either deterministic or stochastic models, which explains why this model was developed using a neural network. Neural networks have the ability to learn about non-linear relationships between the used variables. In this paper a recurrent neural network (Elman model) based forecaster for the prediction of daily maximum concentrations of SO2, O3, PM10, NO2, CO in the city of Palermo is proposed. The effectiveness of the presented forecaster was tested using a time series recorded between 1 January 2003 to 31 December 2004 in eight monitoring stations in urban area of Palermo (Italy). Experimental trials show that the developed and tuned model is appropriate, giving small values of root mean square error (RMSE) , mean absolute error (MAE) and mean square error (MSE). In addition, the related correlation coefficient ranges from 0. 72 to 0. 97 for each forecasted pollutant, underlying a small difference between the forecasted and the measured values. The above results make the proposed forecaster a powerful tool for pollution management systems. [Copyright &y& Elsevier]

Abstract: This paper highlights the effect of emissions regulations on in-use emissions from heavy-duty vehicles powered by different model year engines. More importantly, fuel economy data for pre- and post-consent decree engines are compared. The objective of this study was to determine the changes in brake-specific emissions of NO x as a result of emission regulations, and to highlight the effect these have had on brake-specific CO2 emission; hence, fuel consumption. For this study, in-use, on-road emission measurements were collected. Test vehicles were instrumented with a portable on-board tailpipe emissions measurement system, WVU''s Mobile Emissions Measurement System, and were tested on specific routes, which included a mix of highway and city driving patterns, in order to collect engine operating conditions, vehicle speed, and in-use emission rates of CO2 and NO x . Comparison of on-road in-use emissions data suggests NO x reductions as high as 80% and 45% compared to the US Federal Test Procedure and Not-to-Exceed standards for model year 1995–2002. However, the results indicate that the fuel consumption; hence, CO2 emissions increased by approximately 10% over the same period, when the engines were operating in the Not-to-Exceed region. [Copyright &y& Elsevier]

We present results from an Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 2 program to map CO(2−1) emission in nearby early-type galaxies (ETGs) that host circumnuclear gas disks. We obtained ∼0.″3 resolution Band 6 observations of seven ETGs selected on the basis of dust disks in Hubble Space Telescope images. We detect CO emission in five at high signal-to-noise ratio with the remaining two only faintly detected. All CO emission is coincident with the dust and is in dynamically cold rotation. Four ETGs show evidence of rapid central rotation; these are prime candidates for higher-resolution ALMA observations to measure the black hole masses. In this paper, we focus on the molecular gas and continuum properties. Total gas masses and H2 column densities for our five CO-bright galaxies are on average ∼108M☉ and cm−2 over the ∼kpc-scale disks, and analysis suggests that these disks are stabilized against gravitational fragmentation. The continuum emission of all seven galaxies is dominated by a central unresolved source, and in five we also detect a spatially extended component. The ∼230 GHz nuclear continua are modeled as power laws ranging from to within the observed frequency band. The extended continuum profiles of the two radio-bright (and CO-faint) galaxies are roughly aligned with their radio jet and suggest resolved synchrotron jets. The extended continua of the CO-bright disks are coincident with optically thick dust absorption and have spectral slopes that are consistent with thermal dust emission. [ABSTRACT FROM AUTHOR]

Carbon monoxide is one of the most common toxins encountered in work settings, the gas being emitted in situations where there is incomplete combustion of carbon-containing substances. Its acute and chronic health effects have been well-documented. While identification of dangerous situations and evaluation of control measures are conducted by environmental monitoring, the body burden due to inhalation of carbon monoxide is measured by an individual's blood carboxyhaemoglobin level.Carboxyhaemoglobin level can be measured directly from a blood sample or, indirectly, by measuring the end-expired carbon monoxide level and using the charts provided to read the corresponding carboxyhaemoglobin level. As the end-expired method is not an intervention method, and is therefore easy to conduct, it is being used widely in epidemiological studies and it could also be used for individual measurements. This study presents a better statistical method for validating the end-expired method than the correlation method used and described in previous studies. [ABSTRACT FROM PUBLISHER]

The biogeochemical evaluation toolkit, BGC-val, is a model- and grid-independent Python toolkit that has been built to evaluate marine biogeochemical models using a simple interface. Here, we present the ideas that motivated the development of the BGC-val software framework, introduce the code structure, and show some applications of the toolkit using model results from the Fifth Climate Model Intercomparison Project (CMIP5). A brief outline of how to access and install the repository is presented in Appendix A, but the specific details on how to use the toolkit are kept in the code repository. The key ideas that directed the toolkit design were model and grid independence, front-loading analysis functions and regional masking, interruptibility, and ease of use. We present each of these goals, why they were important, and what we did to address them. We also present an outline of the code structure of the toolkit illustrated with example plots produced by the toolkit. After describing BGC-val, we use the toolkit to investigate the performance of the marine physical and biogeochemical quantities of the CMIP5 models and highlight some predictions about the future state of the marine ecosystem under a business-as-usual CO2 concentration scenario (RCP8.5). [ABSTRACT FROM AUTHOR]

Ground and satellite observations show that air pollution regulations in the United States (US) have resulted in substantial reductions in emissions and corresponding improvements in air quality over the last several decades. However, large uncertainties remain in evaluating how recent regulations affect different emission sectors and pollutant trends. Here we show a significant slowdown in decreasing US emissions of nitrogen oxides (NOx) and carbon monoxide (CO) for 2011-2015 using satellite and surface measurements. This observed slowdown in emission reductions is significantly different from the trend expected using US Environmental Protection Agency (EPA) bottom-up inventories and impedes compliance with local and federal agency air-quality goals. We find that the difference between observations and EPA's NOx emission estimates could be explained by: (i) growing relative contributions of industrial, area, and off-road sources, (ii) decreasing relative contributions of on-road gasoline, and (iii) slower than expected decreases in on-road diesel emissions. [ABSTRACT FROM AUTHOR]

The CHRONOS space mission concept provides time-resolved abundance for emissions and transport studies of the highly variable and highly uncertain air pollutants carbon monoxide and methane, with sub-hourly revisit rate at fine ( ~4 km) horizontal spatial resolution across a North American domain. CHRONOS can provide complete synoptic air pollution maps ("snapshots") of the continental domain with less than 10 min of observations. This rapid mapping enables visualization of air pollution transport simultaneously across the entire continent and enables a sentinel-like capability for monitoring evolving, or unanticipated, air pollution sources in multiple locations at the same time with high temporal resolution. CHRONOS uses a compact imaging gas filter correlation radiometer for these observations, with heritage from more than 17 years of scientific data and algorithm advances by the science teams for the Measurements of Pollution in the Troposphere (MOPITT) instrument on NASA's Terra spacecraft in low Earth orbit. To achieve continental-scale sub-hourly sampling, the CHRONOS mission would be conducted from geostationary orbit, with the instrument hosted on a communications or meteorological platform. CHRONOS observations would contribute to an integrated observing system for atmospheric composition using surface, suborbital and satellite data with atmospheric chemistry models, as defined by the Committee on Earth Observing Satellites. Addressing the U.S. National Academy's 2007 decadal survey direction to characterize diurnal changes in tropospheric composition, CHRONOS observations observations would find direct societal applications for air quality management and forecasting to protect public health. [ABSTRACT FROM AUTHOR]

Since 1994, the In-service Aircraft for a Global Observing System (IAGOS) program has produced in situ measurements of the atmospheric composition during more than 51 000 commercial flights. In order to help analyze these observations and understand the processes driving the observed concentration distribution and variability, we developed the SOFT-IO tool to quantify source-receptor links for all measured data. Based on the FLEXPART particle dispersion model (Stohl et al., 2005), SOFT-IO simulates the contributions of anthropogenic and biomass burning emissions from the ECCAD emission inventory database for all locations and times corresponding to the measured carbon monoxide mixing ratios along each IAGOS flight. Contributions are simulated from emissions occurring during the last 20 days before an observation, separating individual contributions from the different source regions. The main goal is to supply added-value products to the IAGOS database by evincing the geographical origin and emission sources driving the CO enhancements observed in the troposphere and lower stratosphere. This requires a good match between observed and modeled CO enhancements. Indeed, SOFT-IO detects more than 95% of the observed CO anomalies over most of the regions sampled by IAGOS in the troposphere. In the majority of cases, SOFT-IO simulates CO pollution plumes with biases lower than 10-15 ppbv. Differences between the model and observations are larger for very low or very high observed CO values. The added-value products will help in the understanding of the trace-gas distribution and seasonal variability. They are available in the IAGOS database via http://www.iagos.org. The SOFT-IO tool could also be applied to similar data sets of CO observations (e.g., ground-based measurements, satellite observations). SOFT-IO could also be used for statistical validation as well as for intercomparisons of emission inventories using large amounts of data. [ABSTRACT FROM AUTHOR]

We investigate the composition of 63 C-C nonmethane hydrocarbons (NMHCs), methane (CH) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity ( k ) because of their great abundance and their relatively fast reaction rates with OH. [ABSTRACT FROM AUTHOR]

Background: Due to the consequence of industrial CO emission, the surface temperature of Earth is rising at an alarming rate, causing accelerating deadly effects on the environment and living beings. Thus, an approach to mitigate global warming has been proposed by breaking down industrial CO and converting it into useful products. Methods: Lithium nitride (LiN), the only stable alkali metal nitride that reacts readily with CO, has been proposed to use as a means to break down CO. For this, a chemical reactor has been proposed to install at industrial CO-releasing tower to capture CO and allow a heat-releasing reaction into the bioreactor in the presence of LiN to convert it into carbon (C), nitrogen (N), oxygen (O), and lithium cyanamide (LiCN). In order to confirm this theoretical viability of this technology, a series of global environmental issues has also been discussed to neutralize global warming by utilizing this simple technology. Results: The by-products lithium cyanamide (LiCN) is environmentally benign and can be used as fertilizer, and subsequently, the additional products (C, N, and O) from this reaction naturally will mitigate the atmospheric and biospheric chemical cycle. Conclusions: The technology indeed would be an innovative field of carbon management science which will not only break down the deadly CO but also produce useful products like LiCN (a fertilizer) and C, N, and O to balance the atmosphere and biosphere; thus, global warming comes to an end in the near future. [ABSTRACT FROM AUTHOR]

A three-dimensional gridded climatology of carbon monoxide (CO) has been developed by trajectory mapping of global MOZAIC-IAGOS in situ measurements from commercial aircraft data. CO measurements made during aircraft ascent and descent, comprising nearly 41 200 profiles at 148 airports worldwide from December 2001 to December 2012, are used. Forward and backward trajectories are calculated from meteorological reanalysis data in order to map the CO measurements to other locations and so to fill in the spatial domain. This domain-filling technique employs 15 800 000 calculated trajectories to map otherwise sparse MOZAIC-IAGOS data into a quasi-global field. The resulting trajectory-mapped CO data set is archived monthly from 2001 to 2012 on a grid of 5° longitude 5° latitude 1 km altitude, from the surface to 14 km altitude. The mapping product has been carefully evaluated, firstly by comparing maps constructed using only forward trajectories and using only backward trajectories. The two methods show similar global CO distribution patterns. The magnitude of their differences is most commonly 10% or less and found to be less than 30% for almost all cases. Secondly, the method has been validated by comparing profiles for individual airports with those produced by the mapping method when data from that site are excluded. While there are larger differences below 2 km, the two methods agree very well between 2 and 10 km with the magnitude of biases within 20%. Finally, the mapping product is compared with global MOZAIC-IAGOS cruise-level data, which were not included in the trajectory-mapped data set, and with independent data from the NOAA aircraft flask sampling program. The trajectory-mapped MOZAIC-IAGOS CO values show generally good agreement with both independent data sets. Maps are also compared with version 6 data from the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument. Both data sets clearly show major regional CO sources such as biomass burning in Central and southern Africa and anthropogenic emissions in eastern China. While the maps show similar features and patterns, and relative biases are small in the lowermost troposphere, we find differences of ~20% in CO volume mixing ratios between 500 and 300 hPa. These upper-tropospheric biases are not related to the mapping procedure, as almost identical differences are found with the original in situ MOZAIC-IAGOS data. The total CO trajectory-mapped MOZAIC-IAGOS column is also higher than the MOPITT CO total column by 12-16%. The data set shows the seasonal CO cycle over different latitude bands and altitude ranges as well as long-term trends over different latitude bands. We observe a decline in CO over the northern hemispheric extratropics and the tropics consistent with that reported by previous studies using other data sources. We anticipate use of the trajectory-mapped MOZAICIAGOS CO data set as an a priori climatology for satellite retrieval and for air quality model validation and initialization. [ABSTRACT FROM AUTHOR]

Coal plays a vital role in electricity generation worldwide and is expected to contribute significantly to thermal power generation for the foreseeable future, especially in countries such as India. Carbon capture and sequestration technologies therefore become imperative in order to minimize CO emissions. A systematic and comprehensive assessment of the most promising of these technologies-consisting of supercritical boiler parameters, oxy-coal combustion, and low temperature flashing for simultaneous CO and SO capture-for typical Indian environmental and fuel conditions has been carried out in the present study. The results show that up to 93.3 % of CO and 95 % of SO generated during combustion can be captured while producing a sequestration-ready CO stream of 95.5 mol% purity compressed to a supercritical pressure of 110 bar. The energy penalty for this suite of technologies amounts to about 8.5 % drop in the net power plant efficiency to 33 % despite adopting efficiency measures such as supercritical boiler technologies. [ABSTRACT FROM AUTHOR]

Dynamic emission factors and emission inventories of CO, VOC, VOCevap., NOx, SOx and PM of truck in Bangkok, Thailand were developed using IVE (International vehicle emission) model for the year 2012 to 2024. The year 2012 was chosen as base year since fuel quality had been improved from Euro II to Euro IV standard from that year. Speed of truck driven in study area was chosen as variable parameter for sensitivity analysis of its influence to the emissions of air pollutants because there are no further plans in upgrading or improvement of fuel quality during this period. Truck's Bangkok driving cycle was used as input data in the IVE model. Average speeds used in the model simulation were varied from existing condition (15 km/hr) to the maximum of 80 km/hr. It was found that an average speed of 40 km/hr was the optimal speed in reducing of air pollutants emitted from truck. At this speed, reduction of emission factors of air pollutants as compared with current average velocity of 15 km/hr were about 46%, 54%, 16%, 51%, 53% and 27% for CO, VOC, VOCevap., NOx, SOx and PM, respectively. Therefore, efforts in increasing average speed of at least to about 40 km/hr can be used as a measure to achieve the sustainable transport particularly in the green logistic businesses. [ABSTRACT FROM AUTHOR]

The summertime Arctic lower troposphere is a relatively pristine background aerosol environment dominated by nucleation and Aitken mode particles. Understanding the mechanisms that control the formation and growth of aerosol is crucial for our ability to predict cloud properties and therefore radiative balance and climate. We present an analysis of an aerosol growth event observed in the Canadian Arctic Archipelago during summer as part of the NETCARE project. Under stable and clean atmospheric conditions, with low inversion heights, carbon monoxide less than 80 ppbv, and black carbon less than 5 ngm-3, we observe growth of small particles, <20 nm in diameter, into sizes above 50 nm. Aerosol growth was correlated with the presence of organic species, trimethylamine, and methanesulfonic acid (MSA) in particles ~80 nm and larger, where the organics are similar to those previously observed in marine settings. MSA-to-sulfate ratios as high as 0.15 were observed during aerosol growth, suggesting an important marine influence. The organic-rich aerosol contributes significantly to particles active as cloud condensation nuclei (CCN, supersaturation D0.6%), which are elevated in concentration during aerosol growth above background levels of ~100 to ~220 cm-3. Results from this case study highlight the potential importance of secondary organic aerosol formation and its role in growing nucleation mode aerosol into CCNactive sizes in this remote marine environment. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations were employed to investigate the effects of adsorption of toxic carbon monoxide (CO) and nitrogen monoxide (NO) molecules on heterogeneous CZnO nanocage. A detailed analysis of the energetic, geometry, and electronic structure of various CO and NO adsorptions on the cluster surface was performed. It has been shown that CO molecule was adsorbed on the surface of the cluster resulting in more stable complex system, while NO molecule adsorption led to less stable system. These processes also changed the electronic properties of the cluster by reducing the HOMO/LUMO energy gap after adsorption process. Since this phenomenon led to an increment in the electrical conductivity of the cluster at a definite temperature, the CZnO was transformed to a stronger semiconductor substance upon the CO and NO adsorption. We believe that this research may be helpful in the several fields study such as sensor and catalyst investigation. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) has long been considered an environmental pollutant and a poison. Exogenous exposure to amounts of CO beyond the physiologic level of the body can result in a protective or adaptive response. However, as a gasotransmitter, endogenous CO is important for multiple physiologic functions. To date, at least seven distinct methods of delivering CO have been utilized in animal and clinical studies. In this mini-review, we summarize the exogenous CO delivery methods and compare their advantages and disadvantages. [ABSTRACT FROM AUTHOR]

Link Emissions Models estimate traffic-related air pollution emissions at the individual road link level and inform governmental policies for air quality management. The current South Australian Link Emissions Model (CLEM) assumes constant spatiotemporal traffic flow at a single fixed mean speed, a potential limitation as the variability of exhaust emissions with vehicle speed has been established in the literature.We extend CLEM to eliminate the assumption of constant traffic flow, through the derivation of mean Australian vehicle speed distributions for different road types. Specifically, we successfully model the vehicle speed profile data from the second National In-Service Emissions study using Nearest Neighbour Kernel Density Estimation. We propose a mean speed Distribution Link Emissions Model (DLEM) for exhaust emission estimation based on the derived mean speed distributions. DLEM is an augmented, enhanced version of CLEM, accommodating a range of vehicle speeds and road types. The performance of the extended model, DLEM, is analysed in comparison to the current model, CLEM, through a case study analysis of vehicle exhaust emissions on a typical arterial road in Adelaide, South Australia. Results indicate use of DLEM and, by extension, mean vehicle speed distributions, has a strong impact on emission estimation. In particular, the fixed speed model, CLEM, may be substantially underestimating exhaust emissions of carbon monoxide, non-methane volatile organic compounds and particulate matter less than 2.5 μm in diameter. These are common exhaust pollutants that have been extensively linked with adverse health effects including respiratory morbidity and premature mortality. [ABSTRACT FROM AUTHOR]

This experimental study attempts to design and develop a novel carbon-based material fabrication method that implements high voltage AC arc discharge. The carbon-based material is to be used in an electric circuit to build up a gas sensing mechanism. After applying a high AC voltage to the graphite electrodes employed in the experiment, an arc ignites between the electrodes as the gas between them is iodized. In the carbon decomposition process, the arc is employed and results in the fabricated carbon strands. Thereafter, carbon monoxide (CO) in the atmospheric pressure is passed over the electrodes in the Pyrex glass tube chamber where the carbon strand fabrication process takes place. An increment appears in the measured current voltage ( I- V) between the two sides of the carbon strand as the carrier concentration of CO gas is increased from 200 to 800 ppm. Support vector regression (SVR) algorithm was used for data processing with statistical analysis for errors and quality control. [ABSTRACT FROM AUTHOR]

Negative trends of carbon monoxide (CO) concentrations are observed in the recent decade by both surface measurements and satellite retrievals over many regions of the globe, but they are not well explained by current emission inventories. Here, we analyse the observed CO concentration decline with an atmospheric inversion that simultaneously optimizes the two main CO sources (surface emissions and atmospheric hydrocarbon oxidations) and the main CO sink (atmospheric hydroxyl radical OH oxidation). Satellite CO column retrievals from Measurements of Pollution in the Troposphere (MOPITT), version 6, and surface observations of methane and methyl chloroform mole fractions are assimilated jointly for the period covering 2002-2011. Compared to the model simulation prescribed with prior emission inventories, trends in the optimized CO concentrations show better agreement with that of independent surface in situ measurements. At the global scale, the atmospheric inversion primarily interprets the CO concentration decline as a decrease in the CO emissions (-2.3%yr-1), more than twice the negative trend estimated by the prior emission inventories (-1.0%yr-1). The spatial distribution of the inferred decrease in CO emissions indicates contributions from western Europe (-4.0%yr-1), the United States (-4.6%yr-1) and East Asia (-1.2%yr-1), where anthropogenic fuel combustion generally dominates the overall CO emissions, and also from Australia (-5.3%yr-1), the Indo-China Peninsula (-5.6%yr-1), Indonesia (-6.7%yr-1), and South America (-3%yr-1), where CO emissions are mostly due to biomass burning. In contradiction with the bottom-up inventories that report an increase of 2%yr-1 over China during the study period, a significant emission decrease of 1.1%yr-1 is inferred by the inversion. A large decrease in CO emission factors due to technology improvements would outweigh the increase in carbon fuel combustions and may explain this decrease. Independent satellite formaldehyde (CH2O) column retrievals confirm the absence of large-scale trends in the atmospheric source of CO. However, it should be noted that the CH2O retrievals are not assimilated and OH concentrations are optimized at a very large scale in this study. [ABSTRACT FROM AUTHOR]

An experimental-analytical investigation on the emissive behavior of two high-performance motorcycles belonging to the most recent European legislative category was being performed by the Department of Industrial Engineering of the University of Naples Federico II. The study was focused on these vehicles because the pertinent information was not very exhaustive in the scientific literature, with particular reference to the assessment of cold-start extra emissions of this particular two-wheeler vehicular class (Euro-3 legislative category and displacement >750 cm), that is playing a rising central role in private mobility, also in urban context. From this motivation, in this study a calculation procedure was designed and optimized to model the cold-start transient behavior of motorcycles; through this methodology, it is possible to evaluate the cold transient duration, the emitted quantities during the cold phase and the relevant time-dependence function. The whole procedure was applied on the carbon monoxide and unburned hydrocarbon exhaust cold extra emissions of the selected motorcycles, which were measured on the chassis dynamometer. Experimental tests were performed in cold and hot operating conditions, during both driving cycle regulated by law and real-world driving cycles. [ABSTRACT FROM AUTHOR]