Non-methane Volatile Organic Compounds Emissions Research Articles

Historical industrial emissions of non-methane volatile organic compounds in China for the period of 1980–2010

This paper presents a new classification of industrial sector on basis of a source-tracing method for the historical industrial emissions of non-methane volatile organic compounds (NMVOCs). The industrial sources were divided into four major source categories: production of NMVOCs, storage and transport, industrial processes using NMVOCs as raw materials, and processes using NMVOCs-containing products. Multiyear emission inventories of NMVOCs from industrial sources were established for the period of 1980–2010 in China, covering 98 contributing industrial sources. The inventories were developed by the emission factor method, and further gridded at a spatial resolution of 50 km × 50 km based on GIS methodology, using population data as spatial surrogate. The result showed that China's industrial NMVOCs emissions had increased by 11.6 times at an average annual rate of 8.5% from 1.15 Tg in 1980 to 13.35 Tg in 2010. The four major source categories generated 19.6% (2.63 Tg, production of NMVOCs), 9.6% (1.295 Tg, storage and transport), 13.2% (1.769 Tg, industrial processes using NMVOCs as raw materials), and 57.4% (7.662 Tg, processes using NMVOCs-containing products) of the total emissions from China in 2010. Moreover, the top four industrial emissions sources were oil refinery, architectural decoration, machinery equipment and printing, accounted for 48.3% all together. With respect to the spatial distribution, the emissions mostly occurred in the eastern, northern and southern parts of China, all being much higher than that in the western part. The top four emission provinces were Shandong, Jiangsu, Guangdong, and Zhejiang, accounting for 38.3% of the national emissions. As for the past 30 years, the national industrial NMVOCs emissions increased year-by-year, being in pace with the accelerated industrialization process and the sharp economic growth, especially the rapid expansion of the high-emission industries. Particularly, the oil refinery, product oil and solvent distribution, architectural decoration, and mechanical equipment manufacture became the four largest contributors, accounting for 15.9–34.3%, 6.5–10.2%, 7–8%, and 6–7% of national industrial NMVOCs.

Emission, speciation, and evaluation of impacts of non-methane volatile organic compounds from open dump site

Surface emission from Dhapa, the only garbage disposal ground in Kolkata, is a matter of concern to the local environment and also fuels the issues of occupational and environmental health. Surface emission of the Dhapa landfill site was studied using a flux chamber measurement for nonmethane volatile organic compounds (NMVOCs). Eighteen noncarbonyl volatile organic compounds (VOCs) and 14 carbonyl VOCs, including suspected and known carcinogens, were found in appreciable concentrations. The concentrations of the target species in the flux chamber were found to be significantly higher for most of the species in summer than winter. Surface emission rate of landfill gas was estimated by using two different approaches to assess the applicability for an open landfill site. It was found that the emissions predicted using the model Land GEM version 3.02 is one to two orders less than the emission rate calculated from flux chamber measurement for the target species. Tropospheric ozone formation has a serious impact for NMVOC emission. The total ozone-forming potential (OFP) of the Dhapa dumping ground considering all target NMVOCs was estimated to be 4.9E+04 and 1.2E+05 g/day in winter and summer, respectively. Also, it was found that carbonyl VOCs play a more important role than noncarbonyl VOCs for tropospheric ozone formation. Cumulative cancer risk estimated for all the carcinogenic species was found to be 2792 for 1 million population, while the total noncancer hazard index (HI) was estimated to be 246 for the occupational exposure to different compounds from surface emission to the dump-site workers at Dhapa.Implications:This paper describes the real-time surface emission of NMVOCs from an open municipal solid waste (MSW) dump site studied using a flux chamber. Our study findings indicate that while planning for new landfill site in tropical meteorology, real-time emission data must be considered, rather than relying on modeled data. The formation of tropospheric ozone from emitted NMVOC has also been studied. Our result shows how an open landfill site acts as a source and adds to the tropospheric ozone for the airshed of a metropolitan city.

Impacts of NMVOC emissions on human health in European countries for 2000–2010: Use of sector-specific substance profiles

Non-methane volatile organic compounds (NMVOC) are known to cause damages to human health via two main pathways, viz. the direct toxic effects exerted by certain substances (termed here human toxicity) and their indirect effects related to photochemical ozone formation (POF). To comprehensively assess the damages at national level and thus define adequate air pollution abatement policies, substance breakdowns are needed. However, these are not readily available as total NMVOC emissions are only reported at sector level. In this study, we developed a reproducible methodology that combines available speciation profiles, i.e. distributions of substances emitted per type of sources, and sectoral NMVOC information to reach country-specific, substance-specific emission profiles. Annual emission inventories, including 270 single substances and 52 unrefined groups of substances, were determined for 31 European countries within the period 2000–2010. Using life cycle impact assessment methods for POF and human toxicity, impacts on human health were quantified. The results indicated that a strong linear correlation exists between POF impacts and the total NMVOC emissions, suggesting that air pollution abatement policies could use total NMVOC emissions as a proxy for reducing these impacts. Despite underlying uncertainties, the results also demonstrated that the POF impacts from NMVOC are negligible compared to their direct toxic impacts. The analysis of the results revealed that the toxic impacts (i) are caused by few substances, such as formaldehyde, acrolein and furan, (ii) primarily stem from transportation sectors and from residential sources, and (iii) are found not to correlate with total NMVOC emissions. Our findings therefore suggest the need for supporting air pollution abatement strategies with comprehensive impact assessments, which, in addition to complementing emission- and concentration-based indicators, should allow identifying country-specific improvement potentials at substance and sector levels.

Historical gaseous and primary aerosol emissions in the United States from 1990 to 2010

Abstract. An accurate description of emissions is crucial for model simulations to reproduce and interpret observed phenomena over extended time periods. In this study, we used an approach based on activity data to develop a consistent series of spatially resolved emissions in the United States from 1990 to 2010. The state-level anthropogenic emissions of SO2, NOx, CO, NMVOC (non-methane volatile organic compounds), NH3, PM10 and PM2.5 for a total of 49 sectors were estimated based on several long-term databases containing information about activities and emission controls. Activity data for energy-related stationary sources were derived from the State Energy Data System. Corresponding emission factors reflecting implemented emission controls were calculated back from the National Emissions Inventory (NEI) for seven years (i.e., 1990, 1995, 1996, 1999, 2001, 2002 and 2005), and constrained by the AP-42 (US EPA's Compilation of Air Pollutant Emissions Factors) dataset. Activity data for mobile sources including different types of highway vehicles and non-highway equipment were obtained from highway statistics reported by the Federal Highway Administration. The trends in emission factors for highway mobile source were informed by the 2011 National Transportation Statistics. Emissions for all non-energy-related sources were either scaled by the growth ratio of activity indicators or adjusted based on the NEI trends report. Because of the strengthened control efforts, particularly for the power sector and mobile sources, emissions of all pollutants except NH3 were reduced by half over the last two decades. The emission trends developed in this study are comparable with the NEI trend report and EDGAR (Emissions Database for Global Atmospheric Research) data, but better constrained by trends in activity data. Reductions in SO2, NOx, CO and EC (speciation of PM2.5 by SMOKE, Sparse Matrix Operator Kernel Emissions) emissions agree well with the observed changes in ambient SO2, NO2, CO and EC concentrations, suggesting that the various controls on emissions implemented over the last two decades are well represented in the emission inventories developed in this study. These inventories were processed by SMOKE and are now ready to be used for regional chemistry transport model simulations over the 1990–2010 period.

Temporal and spatial variation in recent vehicular emission inventories in China based on dynamic emission factors

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 cars and motorcycles require stricter control for the reduction of CO and NMVOC emissions, while effective reduction of NOx and PM10 emissions can be achieved by better control of heavy-duty vehicles, buses and coaches, and passenger cars. Explicit provincial-level Monte Carlo uncertainty analysis, which quantified for the first time the Chinese vehicular emission uncertainties associated with both COPERT-derived and domestically measured emission factors by vehicle technology, showed that CO, NMVOC, and NOx emissions for the period 2006–2009 were calculated with the least uncertainty, followed by PM10 and CO2, despite relatively larger uncertainties in N2O and CH4 emissions. The quantified low uncertainties of emissions revealed a necessity of applying vehicle technology- and vehicle age-specific dynamic emission factors for vehicular emission estimation, and these improved methodologies are applicable for routine update and forecast of China's on-road motor vehicle emissions. Implications: This paper tracks the temporal and spatial variation characteristics in recent vehicular emission inventories in China based on dynamic emission factors. The fact that CO and NMVOC emissions kept growing at reduced rates and the NOx, PM10, and GHG emissions continued rising rapidly reveals that it was insufficient to bring down the rapid growth of NOx, PM10, and CO2 emissions by merely tightening emission standards and improving fuel quality of motor vehicles. The results will assist decision makers to formulate effective control policies for China's vehicular emissions. The improved methodologies are applicable for routine update of China's vehicular emission inventories.

Large interannual variations in nonmethane volatile organic compound emissions based on measurements of carbon monoxide

AbstractWe present source estimates of atmospheric carbon monoxide from nonmethane volatile organic compound (NMVOC) oxidation during a period of 8 years (1997–2004) using a Bayesian inversion analysis. The optimized global NMVOC‐derived CO source strength indicates a change of a factor of 2 between the 1997–1998 strong El Niño and subsequent La Niña conditions. For comparison, the average 8 year interannual variability (IAV) is 18%. The variation of NMVOC‐derived CO is closely correlated with the Oceanic Niño Index (ONI) and surface temperature. A time‐lagged correlation analysis between ONI and NMVOC‐derived CO inventory indicated El Niño/Southern Oscillation leads the Northern Hemisphere (NH) NMVOC‐derived CO production by about 3 months earlier than the Southern Hemisphere's (SH). The SH NMVOC‐derived CO was positively correlated with the lagged‐ONI (r = 0.57), while the temperature change barely influenced SH NMVOC‐derived CO (r = 0.01). In the NH, temperature was more robustly correlated with NMVOC‐derived CO (r = 0.58) than the lagged‐ONI (r = 0.35). In particular, the extra‐tropical temperature showed a strong correlation (r = 0.90) with the NH NMVOC‐derived CO and suggested its primary role in controlling the interannual variability of the NH NMVOC‐derived CO.

Odour, dust and non-methane volatile organic-compound emissions from tunnel-ventilated layer-chicken sheds: a case study of two farms

An observational study was undertaken to measure odour and dust (PM10 and PM2.5) emission rates and identify non-methane volatile organic compounds (NMVOCs) and odorants in the exhaust air from two tunnel-ventilated layer-chicken sheds that were configured with multi-tiered cages and manure belts. The study sites were located in south-eastern Queensland and the West Gippsland region of Victoria, Australia. Samples were collected in summer and winter on sequential days across the manure-belt cleaning cycle. Odour emissions ranged from 58 to 512 ou/s per 1000 birds (0.03–0.27 ou/s.kg) and dust emission rates ranged 0.014–0.184 mg/s per 1000 birds for PM10 and 0.001–0.190 mg/s per 1000 birds for PM2.5. Twenty NMVOCs were identified, including three that were also identified as odorants using thermal desorption–gas chromatography–mass spectrometry/olfactometry analysis. Odour emission rates were observed to vary with the amount of manure accumulation on the manure belts, being lowest 2–4 days after removing manure. Odour emission rates were also observed to vary with diurnal and seasonal changes in ventilation rate. Dust emissions were observed to increase with ventilation rate but not with manure accumulation. Some NMVOCs were identified at both farms and in different seasons whereas others were observed only at one farm or in one season, indicating that odorant composition was influenced by farm-specific practices and season.

The formaldehyde budget as seen by a global-scale multi-constraint and multi-species inversion system

Abstract. For the first time, carbon monoxide (CO) and formaldehyde (HCHO) satellite retrievals are used together with methane (CH4) and methyl choloroform (CH3CCl3 or MCF) surface measurements in an advanced inversion system. The CO and HCHO are respectively from the MOPITT and OMI instruments. The multi-species and multi-satellite dataset inversion is done for the 2005–2010 period. The robustness of our results is evaluated by comparing our posterior-modeled concentrations with several sets of independent measurements of atmospheric mixing ratios. The inversion leads to significant changes from the prior to the posterior, in terms of magnitude and seasonality of the CO and CH4 surface fluxes and of the HCHO production by non-methane volatile organic compounds (NMVOC). The latter is significantly decreased, indicating an overestimation of the biogenic NMVOC emissions, such as isoprene, in the GEIA inventory. CO and CH4 surface emissions are increased by the inversion, from 1037 to 1394 TgCO and from 489 to 529 TgCH4 on average for the 2005–2010 period. CH4 emissions present significant interannual variability and a joint CO-CH4 fluxes analysis reveals that tropical biomass burning probably played a role in the recent increase of atmospheric methane.

Characterizing odorous emissions using new software for identifying peaks in chemometric models of gas chromatography–mass spectrometry datasets

The task of identifying individual compounds within complex gas chromatography – mass spectrometry (GC–MS) chromatograms is made more difficult by interferences between peaks with similar mass spectra eluting at the same time, typically against a background of chemical and electronic noise. Although chemometric techniques like parallel factor analysis and multivariate curve resolution can help to purify spectra and improve correlations with reference compounds, file incompatibilities between GC–MS acquisition software and modeling software prevent the modeled spectra from being easily compared to spectra in reference libraries. In this paper we present an enhancement to OpenChrom, an open-source software for chromatography and mass spectrometry, which implements the automated cross-matching of modeled spectra to NIST08 and NIST11 mass spectral databases. The benefits of this approach are demonstrated using a complex environmental dataset consisting of non-methane volatile organic compound emissions sampled on an Australian poultry farm.

Emission factors of gaseous carbonaceous species from residential combustion of coal and crop residue briquettes

Experiments were performed to measure the emission factors (EFs) of gaseous carbonaceous species, such as CO2, CO, CH4, and non-methane volatile organic compounds (NMVOCs), from the combustion of five types of coal of varying organic maturity and two types of biomass briquettes under residential burning conditions. Samples were collected in stainless steel canisters and 2,4-dinitrophenylhydrazine (DNPH) cartridges and were analyzed by GC-FID/MS and HPLC, respectively. The EFs from crop residue briquette burning were generally higher than those from coals, with the exception of CO2. The dominant NMVOC species identified in coal smoke were carbonyls (41.7%), followed by C2 unsaturated hydrocarbons (29.1%) and aromatics (12.1%), while C2 unsaturated hydrocarbons were the dominant species (68.9%) emitted from the combustion of crop residue briquettes, followed by aromatics (14.4%). A comparison of burning normal crop residues in stoves and the open field indicated that briquettes emitted a larger proportion of ethene and acetylene. Both combustion efficiency and coal organic maturity had a significant impact on NMVOC EFs from burning coal: NMVOC emissions increased with increasing coal organic maturity but decreased as the combustion efficiency improved. Emissions from the combustion of crop residue briquettes from stoves occurred mainly during the smoldering process, with low combustion efficiency. Therefore, an improved stove design to allow higher combustion efficiency would be beneficial for reducing emissions of carbonaceous air pollutants.

비메탄계 휘발성유기화합물에 의한 간접 온실효과의 산출

Indirect <TEX>$CO_2$</TEX> effect due to non-methane volatile organic compound (NMVOC) emissions from solvent and product use and fugitive NMVOC emissions from fuels in the Republic of Korea and 13 Annex I countries under United Nations Framework on Climate Change were estimated and the proportions of them to total greenhouse gas (GHG) emissions ranged from 0.092% to 0.45% in 2006. Indirect greenhouse effect (<TEX>$CO_2$</TEX>, <TEX>$CH_4$</TEX>, and <TEX>$O_3$</TEX>) were estimated at 13 photochemical assessment monitoring sites in the Republic of Korea using concentrations of 8 NMVOCs of which indirect global warming potential (GWP) were available. The contribution of toluene to mixing ratio was highest at 11 sites and however, the contribution of toluene to indirect greenhouse effect was highest at nine sites. In contrast to toluene, the contributions of ethane, butane, and ethylene were enhanced. The indirect greenhouse effects of ethane and propane, of which ozone formation potentials are the lowest and the third lowest respectively among targeted 10 NMVOCs, ranked first and fourth highest respectively. Acetaldehyde has relatively higher maximum incremental reactivity and is classified as probable human carcinogen however, its indirect GWP ranked second lowest.

The effect of forest fires in emissions of biogenic volatile organic compounds and windblown dust over urban areas

This study examines the impact of forest fires on natural biogenic volatile organic compounds (BVOCs) and windblown dust emissions over urban areas; specifically over the Athens larger urban zone for the reference year 2008. The area spans a continuum of urban–suburban–wild lands and suffers air quality problems with respect to particulate matter (PM) which are frequently exacerbated during the summer due also to forest fire events. Although the anthropogenic, natural and forest fire emissions in the area have been well documented in the past, the indirect effect of forest fires on natural emissions has not been estimated. A brief description of the area and the history of forest fires events during the period 2000–2008 are presented together with an emission inventory for particulate matter (PM2.5 and PM2.5–10) and non-methane VOC (NMVOC), precursor to PM, from anthropogenic and natural sources for the reference year 2008. The effect of large forest fires (over 40 ha) during the period 2000–2008 on natural emissions is examined with respect also to the spatial and temporal distribution and their relative contribution to total emissions over the area. Moreover, the effect of several parameters and assumptions used in natural emissions calculations pre and post-fire events is discussed. The results indicate that there is a trade-off between fire effects that can result in an increase in PM10 windblown dust emissions but decrease of BVOCs emissions due to vegetation reduction. The changes in natural BVOCs and PM10 emissions over the selected area are rather small, specifically 3.5% and 1.7%, respectively. Changes in the relative contribution of natural to total PM10 and NMVOC emissions in the area due to forest fires was also found small, approximately 0.5% and 0.7%, respectively. The contribution of anthropogenic emissions appears to dramatically outweigh the potential effects on air quality from natural emissions and their changes due to large forest fires. Therefore, more attention should be given to mitigating the anthropogenic emissions in the area for the purposes of promoting air quality.

Variations in emission rates from solvent use in the residential sector: the case of Greece

Solvent use is the second most significant source of anthropogenic non-methane volatile organic compound emissions in Europe, as well as in Greece, the residential solvent use being the second most important source of solvent emissions. The methodology used so far in Greece and other countries for estimating residential solvent emissions adopts literature-proposed average per person emission factors and population data. The methodology developed in this work involves the determination of solvent-containing product groups and the solvent content of products, along with the collection, evaluation and elaboration of a large amount of statistical data concerning the domestic supply of products consumed in the residential sector. The emission calculations are performed on the basis of the amount of the solvent-containing products consumed. Two hundred and sixty-six solvent-containing products used in the residential sector are classified into five groups and 24 sub-categories of similar products and an extensive field survey is carried out in order to determine the solvent content of the products. Time series of total emissions for the period 1995–2007 indicate that there is an increasing trend of total residential solvent emissions in Greece. Cosmetics, do it yourself and car care products are the most important emitting categories of residential solvent use. The resulted emission rates (expressed per capita and per year) are greater than those proposed in the literature and they approach in better way local characteristics, as well as their evolution. The methodology developed and the updated emissions rates could be useful in other counties of similar consumption behaviours, economic situation or climate conditions.

Characterizing non-methane volatile organic compounds emissions from a swine concentrated animal feeding operation

Emissions of non-methane volatile organic compounds (NMVOCs) were determined from a swine concentrated animal feeding operation (CAFO) in North Carolina. NMVOCs were measured in air samples collected in SUMMA and fused-silica lined (FSL) canisters and were analyzed using a gas chromatography flame ionization detection (GCeFID) system. Measurements were made from both an anaerobic lagoon and barn in each of the four seasonal sampling periods during the period June 2007 through April 2008. In each sampling period, nine to eleven canister samples were taken from both the anaerobic lagoon and barn over a minimum of four different days during a period of w1 week. Measurements of meteorological and physiochemical parameters were also made during the sampling period. In lagoon samples, six NMVOCs were identified that had significantly larger emissions in comparison to other NMVOCs. This included three alcohols (ethanol, 2-ethyl-1-hexanol, and methanol), two ketones (acetone and methyl ethyl ketone (MEK)) and an aldehyde (acetaldehyde). The overall average fluxes for these NMVOCs, ranged from 0.18 m gm �2 min � 1 for 2-ethyl-1-hexanol to 2.11 m gm �2 min �1 for acetone, with seasonal fluxes highest in the summer for four (acetone, acetaldehyde, 2-ethyl-1-hexanol and MEK) of the six compounds In barn samples, there were six NMVOCs that had significantly larger concentrations and emissions in comparison to other NMVOCs. These consisted of two alcohols (methanol and ethanol), an aldehyde (acetaldehyde), two ketones (acetone and 2,3-butanedione), and a phenol (4-methylphenol). Overall average barn concentration ranged from 2.87 ppb for 4-methylphenol to 16.12 ppb for ethanol. Overall average normalized barn emission rates ranged from 0.10 g day �1 AU �1 (1 AU (animal unit) ¼ 500 kg of live animal weight) for acetaldehyde to 0.45 g day �1 AU �1 for ethanol. The NMVOCs, 4methylphenol and 2,3-butanedione, which have low odor thresholds (odor thresholds ¼ 1.86 ppb and 0.068e0.264 ppb for 4-methylphenol, and ¼ 4.37 ppb and 1.42e7.39 ppb for 2-3-butanedione) and an offensive odor were identified in canister samples. Both 4-methylphenol and 2,3-butanedione barn concentrations exceeded their odor thresholds frequently. HAPs were identified in lagoon samples (methanol, acetaldehyde and MEK) and barn samples (methanol, acetaldehyde and 4-methylphenol) that were also classified as NMVOCs with significantly larger lagoon and barn emissions in comparison with other NMVOCs. The overall average lagoon fluxes and overall average normalized barn emissions for NMVOCs reported in this paper were used to estimate their North Carolina swine CAFO emissions. Of the NMVOCs, ethanol was estimated to have the largest North Carolina swine CAFO emission at 206,367 kg yr �1 . The barns were found to have higher emissions than the lagoons for all NMVOCs, contributing between 68.6 to w100% of individual compounds estimated North Carolina swine CAFO emissions.

Non-methane volatile organic compound emission inventories in Beijing during Olympic Games 2008

Abstract Non-methane volatile organic compounds (NMVOCs) play important roles in ground-level ozone and secondary organic aerosol (SOA) formation. To evaluate the effectiveness of air quality control measures in Beijing in 2008, NMVOC emission inventories were compiled for June, July, August, and September with emission factors and updated activity data. Total NMVOC emissions were 22.6, 20.2, 14.9, and 14.6 Gg in June, July, August, and September, respectively. Anthropogenic NMVOC emissions were 45% lower in August than June; vehicles, solvent utilization, industrial processing, and miscellaneous sources declined by 66, 48, 15, and 75%, respectively. Anthropogenic NMVOC emissions increased in September compared with August. NMVOC emissions from petroleum storage and transport varied little during these months because of the installation of low-fugitive facilities. Reduced emissions from vehicles, industrial processing, and petroleum storage and transport contributed to the total anthropogenic reduction. Inventory uncertainties were evaluated to be [−51%, +126%], [−56%, +146%], [−58%, +161%], and [−52%, +133%] in June, July, August, and September, respectively, at the 95% confidence level.

Quantifying the impact of model errors on top-down estimates of carbon monoxide emissions using satellite observations

[1] We conduct inverse analyses of atmospheric CO, using the GEOS-Chem model and observations from the Measurement of Pollution in the Troposphere satellite instrument, to quantify the potential contribution of systematic model errors on top-down source estimates of CO. We assess how the specification of the source of CO from the oxidation of biogenic nonmethane volatile organic compounds (NMVOCs) in the inversion impacts the top-down estimates. Our results show that when the NMVOC source of CO is comparable to or larger than the combustion source, optimizing the CO from NMVOC emissions on larger spatial scales than the combustion emissions could result in significant overadjustment for the a posteriori CO emissions and could lead to negative sources of CO, such as we found for the top-down South American emissions in June. We quantify the impact of aggregation errors on the source estimates, associated with conducting the inversion at a lower resolution than the atmospheric model. We find that aggregating the emissions across spatial scales in which the a priori error in the emissions changes sign could introduce biases exceeding 20% in the flux estimates since the inversion cannot correct the a priori error by uniformly scaling the emissions across the region. We also use the GEOS-3 and GEOS-4 meteorological fields in GEOS-Chem to examine the impact of discrepancies in atmospheric transport and in the atmospheric OH distribution on the source estimates. We find that the differences in the OH distribution and transport fields associated with the GEOS-3 and GEOS-4 products introduce comparably large differences of as much as 20% in the source estimates. Our results indicate that mitigating systematic model error is critical for improving the accuracy of the inferred source estimates.

The influence of emission changes on ozone concentrations and nitrogen deposition into the southern North Sea

The impact of changes in amount of emission for NO X (Nitrogen monoxide NO + Nitrogen dioxide NO 2 ) and NMVOC (Non Methane Volatile Organic Compounds) on concentrations of ozone (O 3 ), NO x , nitric acid (HNO 3 ) and on nitrogen deposition in the area of the southern North Sea are investigated. One reference case for the period 16 June till 20 June, 1998 and six emission scenarios are calculated. Spatial and temporal emission patterns are kept and overall emission factors are used that correspond to years 1998 (reference), 1970 and 2010. Some more artificial emission scenarios are constructed to investigate the effect of a changed ratio of NO x to NMVOC emissions. The meteorology is unchanged for all scenarios. The studies are performed with the meteorology/chemistry model M-SYS (METRAS/MECTM) including a simple aerosol chemistry and using a horizontal resolution of 8 km. Changes in emissions of NMVOC and NO x cause nonlinear changes in O 3 , NO x and HNO 3 concentrations. The concentration changes depend on emission changes and on changes in the ratio of NMVOC to NO X emissions. The whole area, over land and water, turns out to be in the NMVOC limited regime. Ozone scenario concentrations linearly depend on the ratio of NMVOC to NO x emissions. NO x concentrations linearly depend on changes in the total emissions of NO x and NMVOC. They are inversely related to changes in the ratio of NMVOC to NO x emissions. HNO 3 concentrations mainly depend on the total emission changes with NO x emission changes being of doubled relevance compared to NMVOC emission changes. The same relation is found for nitrogen deposition. Compared to mean ozone concentrations from the reference case, higher (lower) NO x emissions reduce (increase) ozone concentrations, while HNO 3 concentrations are increased (reduced). In contrast, reduced (increased) NMVOC emissions reduce (increase) both, ozone and HNO 3 concentrations and, in addition, the nitrogen deposition.

Atmospheric Emission Inventory for Natural and Anthropogenic Sources and Spatial Emission Mapping for the Greater Athens Area

A spatially, temporally and chemically resolved emission inventory for particulate matter and gaseous species from anthropogenic and natural sources was created for the Greater Athens Area (GAA; base year, 2007). Anthropogenic sources considered in this study include combustion (industrial, non-industrial, commercial and residential), industrial production, transportation, agriculture, waste treatment and solvent use. The annual gaseous pollutants (ΝΟx, SOx, non-methane volatile organic compounds (NMVOCs), CO and ΝΗ3) and particulate matter (PM2.5 and PM2.5–10) emissions were derived from the UNECE/EMEP database for most source sectors (SNAP 1–9; 50 × 50 km2) and their spatial resolution was increased using surrogate spatial datasets (land cover, population density, location and emissions of large point sources, emission weighting factors for the GAA; 1 × 1 km2). The emissions were then temporally disaggregated in order to provide hourly emissions for atmospheric pollution modelling using monthly, daily and hourly disintegration coefficients, and additionally the chemical speciation of size-segregated particles and NMVOCs emissions was performed. Emissions from agriculture (SNAP 10) and natural emissions of particulate matter from the soil (by wind erosion) and the sea surface and of biogenic gaseous pollutants from vegetation were also estimated. During 2007 the anthropogenic emissions of CO, SOx, NOx, NMVOCs, NH3, PM2.5 and PM2.5–10 from the GAA were 151,150, 57,086, 68,008, 38,270, 2,219, 9,026 and 3,896 Mg, respectively. It was found that road transport was the major source for CO (73.3%), NMVOCs (31.6%) and NOx (35.3%) emissions in the area. Another important source for NOx emissions was other mobile sources and machinery (23.1%). Combustion for energy production and transformation industries was the major source for SOx (38.5%), industrial combustion for anthropogenic PM2.5–10 emissions (59.5%), whereas non-industrial combustion was the major source of PM2.5 emissions (49.6%). Agriculture was the primary NH3 source in the area (72.1%). Natural vegetation was found to be an important source of VOCs in the area which accounted for approximately the 5% of total VOCs emitted from GAA on a typical winter day. The contribution of sea-salt particles to the emissions of PM2.5 was rather small, whereas the emissions of resuspended dust particles exceeded by far the emissions of PM2.5 and PM2.5–10 from all anthropogenic sources.

Source identification and budget analysis on elevated levels of formaldehyde within the ship plumes: a ship-plume photochemical/dynamic model analysis

Abstract. Elevated levels of formaldehyde (HCHO) along the ship corridors have been observed by satellite sensors, such as ESA/ERS-2 GOME (Global Ozone Monitoring Experiment), and were also simulated by global 3-D chemistry-transport models. In this study, three likely sources of the elevated HCHO levels in the ship plumes as well as their contributions to the elevated HCHO levels (budget) were investigated using a newly-developed ship-plume photochemical/dynamic model: (1) primary HCHO emission from ships; (2) secondary HCHO production via the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) emitted from ships; and (3) atmospheric oxidation of CH4 within the ship plumes. For this ship-plume modelling study, the ITCT 2K2 (Intercontinental Transport and Chemical Transformation 2002) ship-plume experiment, which was carried out about 100 km off the coast of California on 8 May 2002 (11:00 local standard time), was chosen as a base study case because it is the best defined in terms of (1) meteorological data, (2) in-plume chemical composition, and (3) background chemical composition. From multiple ship-plume model simulations for the ITCT 2K2 ship-plume experiment case, CH4 oxidation by elevated levels of in-plume OH radicals was found to be the main factor responsible for the elevated levels of HCHO in the ITCT 2K2 ship-plume. More than ~88% of the HCHO for the ITCT 2K2 ship-plume is produced by this atmospheric chemical process, except in the areas close to the ship stacks where the main source of the elevated HCHO levels would be primary HCHO from the ships (due to the deactivation of CH4 oxidation from the depletion of in-plume OH radicals). Because of active CH4 oxidation by OH radicals, the instantaneous chemical lifetime of CH4 (τCH4) decreased to ~0.45 yr inside the ship plume, which is in contrast to τCH4 of ~1.1 yr in the background (up to ~41% decrease) for the ITCT 2K2 ship-plume case. A variety of likely ship-plume situations at three different latitudinal locations within the global ship corridors was also studied to determine the enhancements in the HCHO levels in the marine boundary layer (MBL) influenced by ship emissions. It was found that the ship-plume HCHO levels could be 19.9–424.9 pptv higher than the background HCHO levels depending on the latitudinal locations of the ship plumes (i.e., intensity of solar radiation and temperature), MBL stability and NOx emission rates. On the other hand, NMVOC emissions from ships were not found to be a primary source of photochemical HCHO production inside ship plumes due to their rapid and individual dilution. However, the diluted NMVOCs would contribute to the HCHO productions in the background air.

Trend detection in satellite observations of formaldehyde tropospheric columns

Being an intermediate product in the oxidation of a large number of non‐methane volatile organic compounds (NMVOCs), formaldehyde (H2CO) is a useful indicator of biogenic, pyrogenic and anthropogenic hydrocarbon emissions. We present the first trend study performed on H2CO satellite columns, retrieved from the GOME and SCIAMACHY instruments between 1997 and 2009. A linear model with a seasonal component is used to fit the time series of monthly averaged columns. The error and statistical significance of the inferred trends are estimated. The study focuses on Asia but results are also provided for large cities worldwide. Statistically significant positive trends of formaldehyde columns are observed over northeastern China (4% yr−1) and India (1.6% yr−1), related to strong increases in anthropogenic NMVOC emissions, whereas negative trends of about −3% yr−1 are observed over Tokyo as well as over cities of the northeast U.S. urban corridor as a result of effective pollution regulation measures.