Atmospheric Environment (v.92, #C)

A multi-residue method for characterization of endocrine disruptors in gaseous and particulate phases of ambient air by Fabrice Alliot; Elodie Moreau-Guigon; Catherine Bourges; Annie Desportes; Marie-Jeanne Teil; Martine Blanchard; Marc Chevreuil (1-8).
A number of semi-volatile compounds occur in indoor air most of them being considered as potent endocrine disruptors and thus, exerting a possible impact upon health. To assess their concentration levels in indoor air, we developed and validated a method for sampling and multi-residue analysis of 58 compounds including phthalates, polycyclic aromatic hydrocarbons (PAHs), polybromodiphenylethers (PBDEs), polychlorobiphenyls (PCBs), parabens, bisphenol A (BPA) and tetrabromobisphenol A (TBBPA) in gaseous and particulate phases of air. We validated each step of procedures from extraction until analysis. Matrice spiking were performed at extraction, fractionation and purification stages. The more volatile compounds were analyzed with a gas chromatography system coupled with a mass spectrometer (GC/MS) or with a tandem mass spectrometer (GC/MS/MS). The less volatile compounds were analyzed with a liquid chromatography system coupled with a tandem mass spectrometer (LC/MS/MS). Labeled internal standard method was used ensuring high quantification accuracy. The instrumental detection limits were under 1 pg for all compounds and therefore, a limit of quantification averaging 1 pg m−3 for the gaseous and the particulate phases and a volume of 150 m3, except for phthalates, phenol compounds and BDE-209. Satisfactory recoveries were found except for phenol compounds. That method was successfully applied to several indoor air samples (office, apartment and day nursery) and most of the targeted compounds were quantified, mainly occurring in the gaseous phase. The most abundant were phthalates (up to 918 ng m−3 in total air), followed by PCBs > parabens > BPA > PAHs > PBDEs.
Keywords: Multi-residue; Endocrine disruptors; Air; Mass spectrometry; Chromatography;

Submicron particle number concentration (PNC) and particle size distribution (PSD) in the size range of 5.6–560 nm were investigated in Singapore from 27 June 2009 through 6 September 2009. Slightly hazy conditions lasted in Singapore from 6 to 10 August. Backward air trajectories indicated that the haze was due to the transport of biomass burning impacted air masses originating from wild forest and peat fires in Sumatra, Indonesia. Three distinct peaks in the morning (08:00–10:00), afternoon (13:00–15:00) and evening (16:00–20:00) were observed on a typical normal day. However, during the haze period no distinct morning and afternoon peaks were observed and the PNC (39,775 ± 3741 cm−3) increased by 1.5 times when compared to that during non-haze periods (26,462 ± 6017). The morning and afternoon peaks on the normal day were associated with the local rush hour traffic while the afternoon peak was induced by new particle formation (NPF). Diurnal profiles of PNCs and PSDs showed that primary particle peak diameters were large during the haze (60 nm) period when compared to that during the non-haze period (45.3 nm). NPF events observed in the afternoon period on normal days were suppressed during the haze periods due to heavy particle loading in atmosphere caused by biomass burning impacted air masses.
Keywords: Submicron particles; Haze; Particle size distributions; Backward trajectories; New particle formation;

Explorative forecasting of air pollution by D. Domańska; M. Wojtylak (19-30).
In the paper a model to predict immission concentrations of PM10, SO2, O3 for a selected number of forward time steps is proposed. The proposed model (e-APFM) is an extension of the Air Pollution Forecasting Model (APFM). APFM requires historical data for a large number of points in time, particularly weather forecast, meteorological and pollution data. e-APFM additionally requires information about the wind direction in sectors and meteorological station. This information also permits pollution at meteorological stations for which we do not have the necessary data (in particular the data about pollution) to be forecast. The experimental verification of the proposed model was conducted on the data from the Institute of Meteorology and Water Management in Poland over a period of two years (between January 2011 and December 2012). Experiments show that the e-APFM method has lower deviations between the measured and predicted concentrations compared to the APFM method for the first day and similar deviations for the next two days (for hourly values) and for the first day and mostly worse for the second and third day (for daily values).
Keywords: Prediction; Air pollution forecasting; Fuzzy numbers; Data mining; Expert system;

Cyclist exposure to UFP and BC on urban routes in Antwerp, Belgium by Jan Peters; Joris Van den Bossche; Matteo Reggente; Martine Van Poppel; Bernard De Baets; Jan Theunis (31-43).
Ultrafine particles (UFP) and black carbon (BC) concentrations show a highly dynamic micro-variability in urban area. Mobile monitoring using a bicycle platform (354 runs in 1 month) was adopted in this study to characterize the micro-variability in relation to traffic intensity, street topology and meteorological conditions. For UFP and BC a positive relationship was demonstrated between pollutant concentration and traffic intensity. In addition, the distance to the traffic and the street topology were the dominant factors influencing the UFP and BC concentrations. A high variability between streets and even within streets was observed, and also between days and hour of the day. The exposure of cyclists in urban environments is strongly linked to the spatio-temporal variability of the pollutant concentrations. Fixed-track comparisons through time revealed significant differences in exposure between days and hour of the day, but even more importantly due to the occurrence of peak concentrations along the cycling track. Peaks were mainly found near busy cross-roads and in tunnels.
Keywords: Urban air quality; Mobile monitoring; Space and time variability; Peak concentration; Hot-spot; High resolution; Mapping;

This study investigates the parameterization of fog visibility and its relationship with microphysical properties. Fog visibility and droplet spectra are observed for four fog cases in the North China Plain from November to December in 2009. The calculated visibility using droplet spectra is similar to the observed visibility for the dense fogs, but is higher than the observed visibility during the relatively light fogs. Two parameterization schemes of fog visibility from previous studies are applied to the four fog cases. The parameterization considering only liquid water content (LWC) has an overestimation of about 70%, while the parameterization using both LWC and Nd has relative errors within 40%, compared to the calculated visibility. However, much larger relative errors are found between the parameterized and the observed visibilities, especially in the relatively light fogs. By slightly changing the coefficients in the parameterization schemes, we found that the scheme considering only LWC fits the calculated visibility with relative errors within 20%, and that the scheme considering both LWC and Nd with relative errors within 5%. Much larger changes of the coefficients are needed in order to best-fit the observed visibility, but still with relative errors larger than 20%. Detailed analyses of the inconsistencies between the calculated, observed and parameterized visibility suggest that the effect of aerosol extinction should be considered in the visibility parameterizations of fogs in the North China plain and other polluted areas.
Keywords: Fog visibility; Liquid water content; Droplet number concentration; Visibility parameterization; North China Plain;

Indoor PAHs at schools, homes and offices in Rome, Italy by P. Romagnoli; C. Balducci; M. Perilli; M. Gherardi; A. Gordiani; C. Gariazzo; M.P. Gatto; A. Cecinato (51-59).
Indoor and outdoor concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with PM2.5 particles were monitored in three microenvironments (schools, homes and offices) in the city of Rome, Italy, between winter 2011 and summer 2012. Molecular signatures and indoor/outdoor concentration ratios of PAHs were investigated, with special emphasis on carcinogenic congeners. At indoor locations, total PAHs ranged, on average, from 1.8 to 8.4 ng/m3 in winter and from 0.30 to 1.35 ng/m3 in spring/summer. Outdoors, total PAH concentrations were found to reach 6.3–17.9 ng/m3 in winter and 0.42–1.74 ng/m3 in spring-summer. Indoors, the concentration of benzo[a]pyrene (BaP) was as high as 1.1 ng/m3 in winter and below 0.1 ng/m3 in the warm season, independently of site type; the yearly average remained below the European guideline value. The indoor/outdoor concentration ratios of individual compounds were lower than one for most of congeners, suggesting that outdoor sources were predominant. Nonetheless, the percentages of PAH compounds changed with sites and seasons; in particular, in spring/summer, the concentration of BaP at our sites was more than twice that recorded at the regional network stations.
Keywords: Indoor air; PAHs; Airborne particulates; Indoor/outdoor concentration ratio; PM2.5; Rome;

Impacts of the high loadings of primary and secondary aerosols on light extinction at Delhi during wintertime by S. Tiwari; A.K. Srivastava; D.M. Chate; P.D. Safai; D.S. Bisht; M.K. Srivastava; G. Beig (60-68).
High emissions of anthropogenic aerosols over Indo-Gangetic Plain (IGP) inspired continuous measurements of fine particles (PM2.5), carbonaceous aerosols (BC, OC and EC), oxides of nitrogen (NO x ) and estimation of light extinction (b ext) and absorption (b abs) coefficients over Delhi during high pollution season in winter from December 2011 to March 2012. During study period, the mass concentrations of PM2.5, BC and NO x were 186.5 ± 149.7 μg m−3, 9.6 ± 8.5 μg m−3 and 23.8 ± 16.1 ppb, respectively. The mass concentrations of OC and EC were studied by two different techniques (i) off-line (gravimetric method) and (ii) semi-continuous (optical method) and their mean mass concentrations were 51.1 ± 15.2, 10.4 ± 5.5 μg m−3 and 33.8 ± 27.7, 8.2 ± 6.2 μg m−3, respectively during the study period. The ratios of mass concentration of OC to EC in both cases were in between 4 and 5. The source contribution of carbonaceous aerosols in PM2.5 estimated over 24hrs, during day- and night-time where motor vehicles accounted for ∼69%, 90% and 61% whereas coal combustion accounted for ∼31%, 10% and 39%, respectively. The estimated mean values of b ext and b abs over the station were 700.0 ± 268.6 and 71.7 ± 54.6 Mm−1, respectively. In day and night analysis, b ext is ∼37% higher during night-time (863.4 Mm−1) than in day-time (544.5 Mm−1). Regression analysis between b ext and visibility showed significant negative correlation (r = −0.85). The largest contribution in the light extinction coefficients was found to be due to organic carbon (∼46%), followed by elemental carbon (∼24%), coarse mode particles (∼18%), ammonium sulfate (∼8%) and ammonium nitrate (∼4%). The individual analysis of light extinction due to chemical species and coarse mode particles indicates that scattering type aerosols dominated by ∼76% over the absorbing type. The aforementioned results suggest that the policy-induced control measures at local administration level are needed to mitigate the excess emissions of carbonaceous aerosols over IGP region which ranks highest in India and elsewhere in worldwide.
Keywords: Particulate mass; Carbonaceous aerosols; Extinction coefficient; Indo-Gangetic plain; Meteorological effect;

Indoor air quality in Latino homes in Boulder, Colorado by Luis E. Escobedo; Wyatt M. Champion; Ning Li; Lupita D. Montoya (69-75).
Indoor concentrations of airborne pollutants can be several times higher than those found outdoors, often due to poor ventilation, overcrowding, and the contribution of indoor sources within a home. Americans spend most of their time indoors where exposure to poor indoor air quality (IAQ) can result in diminished respiratory and cardiovascular health. This study measured the indoor air quality in 30 homes of a low-income Latino community in Boulder, Colorado during the summer of 2012. Participants were administered a survey, which included questions on their health conditions and indoor air pollution sources like cigarette smoke, heating fuel, and building materials. Twenty-four hour samples of fine particulate matter (PM2.5) from the indoor air were collected in each home; ambient PM2.5 samples were collected each day as well. Concurrent air samples were collected onto 47 mm Teflo and Tissuquartz filter at each location. Teflo filters were analyzed gravimetrically to measure PM2.5 and their extracts were used to determine levels of proteins and endotoxins in the fine fraction. The Tissuquartz filters were analyzed for elemental and organic carbon content (EC/OC). Results indicated that the indoor air contained higher concentrations of PM2.5 than the ambient air, and that the levels of OC were much higher than EC in both indoor and outdoor samples. This community showed no smoking in their homes and kept furry pets indoors at very low rates; therefore, cooking is likely the primary source of indoor PM. For responders with significant exposure to PM, it appeared to be primarily from occupational environments or childhood exposure abroad. Our findings indicate that for immigrant communities such as this, it is important to consider not only their housing conditions but also the relevant prior exposures when conducting health assessments.
Keywords: Organic carbon; Indoor air quality; Latino; Endotoxin; Fine particulates; Residential;

A multi-year evolution of aerosol chemistry impacting visibility and haze formation over an Eastern Asia megacity, Shanghai by Yanfen Lin; Kan Huang; Guoshun Zhuang; Joshua S. Fu; Qiongzhen Wang; Tingna Liu; Congrui Deng; Qingyan Fu (76-86).
A multi-year (2004–2008) study of horizontal visibility and factors controlling its variations was conducted in Shanghai. The seasonal average visibility in spring, summer, autumn, and winter was 7.7 km, 8.4 km, 8.1 km, and 6.5 km, respectively, significantly exceeding the haze criteria of 10 km throughout all four seasons. Although SO2 and NO2 concentrations gradually shifted to lower levels on an annual basis, no distinct improvement of the annual mean visibility was noticed. Via a grouping method, it was found that the water soluble ions and black carbon were the major contributors to haze formation while the role of mineral aerosol was negligible. Of the ions, SO4 2−, NO3 , NH4 +, K+, and C2O4 2− were most associated with the formation of heavy haze. SO4 2− and NO3 were both found to have significant decreasing trends with annual decreasing rates of 0.96 and 0.56 μg/m3/yr, respectively. Conversely, NH4 + showed a significant increasing trend with the annual increasing rate of 0.52 μg/m3/yr. Based on a quantitative correlation analysis, the roles of NH4 + and Ca2+ on the acids neutralization were almost equivalent in the earlier years of 2004–2005. While the role of Ca2+ had tremendously dropped to less than 23% in the later years of 2006–2008. Intense control measures on the emissions of construction works and roadside dust were the main driving force for the evident decreasing trend of annual Ca2+ concentrations. This study found that the gradual replacement of CaSO4 and Ca(NO3)2 by (NH4)2SO4 and NH4NO3 in aerosol was the major cause of no improvement of the visibility impairment in Shanghai during recent years.
Keywords: Haze; Visibility trend; Chemical species; Aerosol evolution; Ammonium salts;

Wet deposition fluxes of total mercury and methylmercury in core urban areas, Chongqing, China by Yongmin Wang; Yulong Peng; Dingyong Wang; Cheng Zhang (87-96).
Wet deposition fluxes of mercury (Hg) species were estimated during the period from June 2010 to July 2011 at 3 sites in core urban areas in Chongqing, China. Rain water was collected by automatic deposition sampler for total Hg (THg) and methylmercury (MeHg) analyses. Our results showed that annual wet deposition fluxes of THg and MeHg were 28.7 ± 5.1 and 0.28 ± 0.09 μg m−2 yr−1, respectively. We estimate that MeHg wet deposition contributes 9.2–19.6% of the total MeHg flux to a local reservoir. Cumulative THg fluxes collected from nine principal rainfall events (>1.5 μg m−2 yr−1) at three sampling sites accounted for 20% of annual overall THg wet deposition. Statistical analyses yielded significant relationship between rainfall amounts and Hg wet deposition fluxes (r 2 = 0.76, p < 0.01 for THg; r 2 = 0.65, p < 0.01 for MeHg), suggesting that rainfall is one of the most important factors controlling the Hg fluxes. Obvious seasonal variations of THg fluxes were observed, with the maximum value occurring in summer (accounting for 40% of total annual THg deposition) while minimum values occurred in winter in all the three sampling sites. 72-h backward trajectory analysis on nine large deposition events at the three sites, using HYSPLIT model indicated that most of air masses which contain a relatively high precipitation amount and pass through major Hg sources would have an elevated Hg load.
Keywords: Wet deposition fluxes; Mercury; Methylmercury; HYSPLIT;

Atmospheric aerosol particle concentrations have been linked with a wide range of pulmonary and cardio-vascular diseases but the particle properties responsible for these negative health effects are largely unknown. It is often speculated that reactive oxygen species (ROS) present in atmospheric particles lead to oxidative stress in, and ultimately disease of, the human lung. The quantification of ROS is highly challenging because some ROS components such as radicals are highly reactive and therefore short-lived. Thus, fast analysis methods are likely advantageous over methods with a long delay between aerosol sampling and ROS analysis. We present for the first time a detailed comparison of conventional off-line and fast on-line methods to quantify ROS in organic aerosols. For this comparison a new and fast on-line instrument was built and characterized to quantify ROS in aerosol particles with high sensitivity and a limit of detection of 4 nmol H2O2 equivalents per m3 air. ROS concentrations are measured with a time resolution of approximately 15 min, which allows the tracking of fast changing atmospheric conditions. The comparison of the off-line and on-line method shows that, in oxidized organic model aerosol particles, the majority of ROS have a very short lifetime of a few minutes whereas a small fraction is stable for a day or longer. This indicates that off-line techniques, where there is often a delay of hours to days between particle collection and ROS analysis, may severely underestimate true ROS concentrations and that fast on-line techniques are necessary for a reliable ROS quantification in atmospheric aerosol particles and a meaningful correlation with health outcomes.
Keywords: Organic aerosol; Health effects; On-line analysis;

Identification of a point release is a parametric estimation problem associated with the estimation of its parameters namely, location and strength. A least-squares inversion algorithm, free from initial guess of release parameters, is utilized here for the source identification in eleven trials of single continuous point releases conducted during Fusion Field Trials 2007. The source locations are retrieved within an average error of 23 m from their true locations. The maximum and minimum errors in the retrieval of the source location are obtained as 57.3 m and 3 m respectively. The source strength is retrieved within a factor of 1.6 in all the trials. The sensitivity of the source estimation is analysed with respect to (i) variation of grid sizes in discretized space, (ii) inclusion of zero measurements and (iii) addition of new measurements. Posterior uncertainty is mentioned in terms of variance of the source parameters, approximated by using the Hessian of the cost function. In addition, an attempt is made to obtain the minimum number of measurements for a successful source inversion. The study explores the future applicability of this least-squares inversion technique for point source identification.
Keywords: FFT07; Inverse modelling; Least-squares; Source estimation;

Assessment of transboundary ozone contribution toward South Korea using multiple source–receptor modeling techniques by Ki-Chul Choi; Jong-Jae Lee; Chang Han Bae; Cheol-Hee Kim; Soontae Kim; Lim-Seok Chang; Soo-Jin Ban; Suk-Jo Lee; Jongchoon Kim; Jung-Hun Woo (118-129).
Ozone concentrations in East Asia were simulated using the Community Multi-scale Air Quality (CMAQ) model, and its source contributions were estimated by multiple source–receptor modeling techniques. To study relationships between ozone concentrations and precursor emission sources, three approaches were applied to four months (January, April, July, and October 2009) to represent seasonal characteristics and compare results, with a particular focus on South Korea. Brute force (BF) is a traditional sensitivity analysis method used to estimate model output response to an input change. The high-order decoupled direct method (HDDM), a computational method, is an efficient and accurate alternative to the BF method for sensitivity. The Ozone and Particulate Precursor Tagging Methodology (OPTM) provides contribution information quantified by tracking emissions from selected sources throughout the simulation period. The approaches generally show that most of the receptor regions were substantially influenced by emissions from central China, which is the largest anthropogenic emissions source region in East Asia. Local emissions were still major contributors, especially South Korea and Japan during July 2009. On the other hand, a case study of maximum 8-h ozone concentrations derived from CMAQ–OPTM on April 9 in South Korea shows that the NO x and VOCs emissions from China contributed approximately 82% and 91%, respectively, to maximum 8-h ozone in Region 4 (South Korea) without boundary inflow, which indicates that Chinese emissions are the dominant contributor in this episode. A comparison study of the three approaches shows that HDDM tends to estimate biogenic source contributions lower than that from OPTM in China but similar to OPTM in South Korea and Japan. When comparing the BF method and HDDM, the sensitivity results show a reasonably good agreement during a given period. The location- and time-dependent maximum 8-h ozone isopleths over South Korea as a receptor region created by HDDM suggest that most ozone was being transported from central China, whereas almost no ozone was formed locally during April 2009, and local conditions were heavily VOC limited. On the other hand, local emissions were the dominant contributor during July 2009, and every source region showed a NO x -limited regime, which indicates that ozone concentrations in South Korea strongly depend on NO x emissions during this month.
Keywords: Air quality; Ozone; Source–receptor relationships; East Asia; Long-range Transboundary Air Pollutants in Northeast Asia (LTP);

Increasing the spatial resolution of air quality assessments in urban areas: A comparison of biomagnetic monitoring and urban scale modelling by Jelle Hofman; Wouter Lefebvre; Stijn Janssen; Ruben Nackaerts; Siegmund Nuyts; Lars Mattheyses; Roeland Samson (130-140).
Increasing the spatial resolution of air quality assessments in urban environments is designated as a priority area within current research. Biomagnetic monitoring and air quality modelling are both methodologies able to provide information about the spatial variation of particulate pollutant levels within urban environments. This study evaluates both methods by comparing results of a biomagnetic monitoring campaign at 110 locations throughout Antwerp, Belgium, with modelled pollutant concentrations of PM10 and NO2. Due to the relation of biomagnetic monitoring with railway traffic, analyses were conducted for both all locations (n = 110) and railway traffic excluded locations (n = 67). While the general spatial variation, land use comparison and the relation with traffic intensity were comparable between the two applied methodologies, an overall bad agreement is obtained when the methodologies are correlated to each other. While no correlation was found between SIRM and PM10 results (p = 0.75 for n = 110 and p = 0.68 for n = 67), a significant but low (r ≤ 0.33) correlation was found between SIRM and NO2 (p < 0.01 for n = 110 and p = 0.04 for n = 67). While biomagnetic monitoring and air quality modelling are both able to provide high spatial resolution information about urban pollutant levels, we need to take into account some considerations. While uncertainty in the biomagnetic monitoring approach might arise from the processes that determine leaf particulate deposition and the incorporation of multiple emission sources with diverging magnetic composition, air quality modelling remains an approximation of reality which implies its dependency on accurate emission factors, implication of atmospheric processes and representation of the urban morphology. Therefore, continuous evaluation of model performance against measured data is essential to produce reliable model results. Nevertheless, this study demonstrates that in addition to telemetric monitoring networks, the combination of both air quality modelling and biomagnetic monitoring is a valuable approach to provide insights into the variation of atmospheric pollutants in heterogeneous urban environments.
Keywords: Biomonitoring; Modelling; Air pollution; SIRM; Urban; Antwerp;

A corrected formulation of the Multilayer Model (MLM) for inferring gaseous dry deposition to vegetated surfaces by Rick D. Saylor; Glenn M. Wolfe; Tilden P. Meyers; Bruce B. Hicks (141-145).
The Multilayer Model (MLM) has been used for many years to infer dry deposition fluxes from measured trace species concentrations and standard meteorological measurements for national networks in the U.S., including the U.S. Environmental Protection Agency's Clean Air Status and Trends Network (CASTNet). MLM utilizes a resistance analogy to calculate deposition velocities appropriate for whole vegetative canopies, while employing a multilayer integration to account for vertically varying meteorology, canopy morphology and radiative transfer within the canopy. However, the MLM formulation, as it was originally presented and as it has been subsequently employed, contains a non-physical representation related to the leaf-level quasi-laminar boundary layer resistance that affects the calculation of the total canopy resistance. In this note, the non-physical representation of the canopy resistance as originally formulated in MLM is discussed and a revised, physically consistent, formulation is suggested as a replacement. The revised canopy resistance formulation reduces estimates of HNO3 deposition velocities by as much as 38% during mid-day as compared to values generated by the original formulation. Inferred deposition velocities for SO2 and O3 are not significantly altered by the change in formulation (<3%). Inferred deposition loadings of oxidized and total nitrogen from CASTNet data may be reduced by 10–20% and 5–10%, respectively, for the Eastern U. S. when employing the revised formulation of MLM as compared to the original formulation.
Keywords: Dry deposition; Nitric acid; Sulfur dioxide; Ozone; Multi-layer model; Canopy; CASTNet;

Sources of carbonaceous aerosol in the free troposphere by H. Timonen; D.A. Jaffe; N. Wigder; J. Hee; H. Gao; L. Pitzman; R.A. Cary (146-153).
In this study concentrations of organic (OC) and elemental carbon (EC) from free tropospheric (FT) fine particulate matter (PM) were measured from March to September, 2012 with a Semi-Continuous OC/EC carbon aerosol analyzer at the top of Mt. Bachelor (2.8 km a.s.l) in Central Oregon, U.S. The average concentrations of OC and EC in the FT were low (OC: 1.87 ± 6.10, EC: 0.07 ± 0.26 μg m−3; average ± SD) but much higher during specific pollution episodes. During springtime the highest OC and EC concentrations were measured for dry free tropospheric air masses, whereas during summertime the highest OC and EC concentrations were typically measured for more humid air masses that were uplifted from the boundary layer (BL). The highest OC and EC concentrations were measured during biomass burning episodes (3 h average OC: up to 146.0 μg m−3, EC up to 5.5 μg m−3). Elevated OC and EC concentrations were also measured during Asian Long Range Transport (LRT) episodes (OC: up to 3.6 μg m−3, EC up to 1.1 μg m−3). In addition, between episodes, an increase in OC was seen in the afternoon, possibly due to SOA formation. This SOA can then be exported to the FT via diurnal ventilation of the BL. For Asian LRT episodes the OC/EC ratios varied between 8 and 34, with an average of 17.9. For local biomass burning emissions OC/EC ratios were between 25 and 30. Higher OC/EC ratios (30–40) were observed for the biomass burning plumes originating from longer distances, possibly due to SOA formation.
Keywords: Organic carbon; Elemental carbon; Free troposphere; Particulate matter;

Comparative study of ultrafine atmospheric aerosol within a city by I. Salma; T. Borsós; Z. Németh; T. Weidinger; P. Aalto; M. Kulmala (154-161).
Particle number size distributions in a mobility diameter range of 6–1000 nm and size-resolved number concentrations were determined with a time resolution of 10 min for a near-city background, city centre, street canyon and road tunnel environments in Budapest. Median N 6–100 concentrations for the sites listed were 3.1 × 103, 9.3 × 103, 19.4 × 103 and 123 × 103 cm−3, respectively. Contributions of the ultrafine (UF) particles (<100 nm) to the total particle number for all locations were rather large (up to 86%), and do not seem to vary substantially in time. Diurnal variations of the mean N 6–100 concentrations had different patterns for both the various urban sites, and for workdays and weekends. Nucleation strength factor (NSF) was introduced for the first time to quantify the relative importance of new particle formation with respect to all sources of UF particles. During the daytime in summer, nucleation in the near-city background was a major production process of UF particles with a daily mean relative contribution of 42%. In the city centre and street canyon, the daily mean relative contributions of nucleation to the UF particles were 30% and 23%, respectively. Median particle diameters for the background, city centre, street canyon and road tunnel environments were 61, 42, 35 and 42 nm, respectively, so they were jointly influenced with the anthropogenic impact and aerosol ageing. Monthly mean frequency of new particle formation and growth events in the background seems somewhat larger, while it appears smaller for the street canyon in comparison to the city centre.
Keywords: Urban environment; Particle number concentration; Particle number size distribution; Diurnal variation; Nucleation strength factor; Anthropogenic impact;

Variation of secondary coatings associated with elemental carbon by single particle analysis by Guohua Zhang; Xinhui Bi; Junjie He; Duohong Chen; Lo Yin Chan; Guangwu Xie; Xinming Wang; Guoying Sheng; Jiamo Fu; Zhen Zhou (162-170).
The mixing state of elemental carbon (EC) with secondary species has been highlighted as a major uncertainty in assessing its climate impact. However, the extent to which secondary coatings are present on EC and the underlying processes remained poorly understood in China, where there is a high loading of EC produced from extensive usage of fossil fuels and biomass. A single particle aerosol mass spectrometer (SPAMS) was applied to detect the chemical compositions associated with EC at the Guangdong Atmospheric Supersite, China. Efforts were made to track the variation of secondary coatings on EC. It is the first report on the direct observation of secondary compositions associated with EC with high time resolution in China. The hourly average number of EC-containing particles accounted for ∼33% (21–50%) of total analyzed particles over the sampling period. EC was found to be extensively internally mixed with sulfate (97.4% in number), nitrate (89.5%), oxidized organics (69.6%), and/or ammonium (80%). The results also indicate that secondary processing on EC in condensation (0.2–0.5 μm) and droplet (0.7–1.1 μm) modes is different. Active photochemical formation of oxidized organics and ammonium sulfate during daytime, and formation of ammonium nitrate during nighttime led to a distinct diurnal circle of mixing state of EC in the condensation mode. However, the photochemical aging may have limited or negligible influence on the mixing state and growth of EC in the droplet mode. These findings improve the understanding of the evolution of physicochemical properties of EC, and may help to model its climate impact.
Keywords: Mixing state; Elemental carbon; Sulfate; Organics; Single particle; PRD;

Anthropogenic emissions in East Asia have been increasing during the three decades since 1980, as the population of East Asia has grown and the economies in East Asian countries have expanded. This has been particularly true in China, where NO x emissions have been rising continuously. However, because of fuel-gas desulfurization systems introduced as part of China’s 11th Five-Year Plan (2006–2010), SO2 emissions in China reached a peak in 2005–2006 and have declined since then. These drastic changes in emission levels of acidifying species are likely to have caused substantial changes in the precipitation chemistry. The absolute concentration of compounds in precipitation is inherently linked to precipitation amount; therefore, we use the ratio of nitrate ( NO 3 − ) to non-seasalt sulfate (nss- SO 4 2 − ) concentration in precipitation as an index for evaluating acidification, which we call Ratio. In this study, we analyzed the long-term behavior of Ratio in precipitation over the Japanese archipelago during 2000–2011 and estimated the factors responsible for changes in Ratio in precipitation by using a model simulation. This analysis showed that Ratio was relatively constant at 0.5–0.6 between 2000 and 2005, and subsequently increased to 0.6–0.7 between 2006 and 2011. These changes in Ratio corresponded remarkably well to the changes of NO x /SO2 emissions ratio in China; this correspondence suggests that anthropogenic emissions from China were responsible for most of the change in precipitation chemistry over Japan. Sensitivity analysis elucidated that the increase in NO x emissions and the decrease in SO2 emissions contributed equally to the increases in Ratio. Considering both emission changes in China enables to capture the observed increasing trend of Ratio in Japan.Display Omitted
Keywords: Precipitation chemistry; Nitrate to non-seasalt sulfate ratio ( NO 3 − /nss- SO 4 2 − ); NO x to SO2 emission ratio (NO x /SO2); Community multi-scale air quality (CMAQ) model;

Reliability of reflectance measures in passive filters by Carmen Diva Saldiva de André; Paulo Afonso de André; Francisco Marcelo Rocha; Paulo Hilário Nascimento Saldiva; Regiani Carvalho de Oliveira; Julio M. Singer (178-181).
Measurements of optical reflectance in passive filters impregnated with a reactive chemical solution may be transformed to ozone concentrations via a calibration curve and constitute a low cost alternative for environmental monitoring, mainly to estimate human exposure. Given the possibility of errors caused by exposure bias, it is common to consider sets of m filters exposed during a certain period to estimate the latent reflectance on n different sample occasions at a certain location. Mixed models with sample occasions as random effects are useful to analyze data obtained under such setups. The intra-class correlation coefficient of the mean of the m measurements is an indicator of the reliability of the latent reflectance estimates. Our objective is to determine m in order to obtain a pre-specified reliability of the estimates, taking possible outliers into account. To illustrate the procedure, we consider an experiment conducted at the Laboratory of Experimental Air Pollution, University of São Paulo, Brazil (LPAE/FMUSP), where sets of m = 3 filters were exposed during 7 days on n = 9 different occasions at a certain location. The results show that the reliability of the latent reflectance estimates for each occasion obtained under homoskedasticity is k m  = 0.74. A residual analysis suggests that the within-occasion variance for two of the occasions should be different from the others. A refined model with two within-occasion variance components was considered, yielding k m  = 0.56 for these occasions and k m  = 0.87 for the remaining ones. To guarantee that all estimates have a reliability of at least 80% we require measurements on m = 10 filters on each occasion.
Keywords: Passive filters; Air pollution; Reliability; Outliers; Random effects;

Seasonal modeling of PM2.5 in California's San Joaquin Valley by Jianjun Chen; Jin Lu; Jeremy C. Avise; John A. DaMassa; Michael J. Kleeman; Ajith P. Kaduwela (182-190).
California's San Joaquin Valley (SJV) is in non-attainment for the 2006 revised 24-h PM2.5 National Ambient Air Quality Standard (NAAQS or standard) established by the United States Environmental Protection Agency (U.S. EPA). As a part of the emissions control strategy development to bring the SJV into attainment of the standard, the Community Multi-scale Air Quality (CMAQ) model was used to simulate PM2.5 formation and its response to precursor emission reductions. Simulations were conducted for the first (January–March) and fourth (October–December) quarters of 2007 since the 24-h PM2.5 violations typically occur during the winter months. The CMAQ model generally met the PM2.5 model performance criteria and was suitable for the State Implementation Plan (SIP) applications. Sensitivities of the 24-h average PM2.5 concentrations to precursor emissions were investigated based on the baseline 2019 emissions forecast. Reductions in anthropogenic primary PM2.5 and oxides of nitrogen (NO x ) showed the greatest impact on PM2.5 concentrations. Reducing anthropogenic ammonia and sulfur oxides emissions only slightly lowered PM2.5 concentrations, and reducing volatile organic compounds (VOC) emissions provided no benefit in reducing PM2.5 concentrations. Particularly, PM2.5 nitrate, the major PM2.5 component in the SJV showed no response to VOC reductions, which is also supported by additional modeling results from the UCD/CIT airshed model. This study demonstrated that the current strategy of controlling primary PM2.5 and NO x emissions in the SJV will continue to be effective for further reducing PM2.5 in the SJV beyond 2019. It also demonstrated how the CMAQ model can be used to design effective emissions control strategies for regulatory applications.
Keywords: Community Multiscale Air Quality (CMAQ) model; Precursor equivalence ratio; Carrying capacity diagrams; Particulate matter; San Joaquin Valley; Seasonal modeling;

Point source influence on observed extreme pollution levels in a monitoring network by Katherine B. Ensor; Bonnie K. Ray; Sarah J. Charlton (191-198).
This paper presents a strategy to quantify the influence major point sources in a region have on extreme pollution values observed at each of the monitors in the network. We focus on the number of hours in a day the levels at a monitor exceed a specified health threshold. The number of daily exceedances are modeled using observation-driven negative binomial time series regression models, allowing for a zero-inflation component to characterize the probability of no exceedances in a particular day. The spatial nature of the problem is addressed through the use of a Gaussian plume model for atmospheric dispersion computed at locations of known emissions, creating covariates that impact exceedances. In order to isolate the influence of emitters at individual monitors, we fit separate regression models to the series of counts from each monitor. We apply a final model clustering step to group monitor series that exhibit similar behavior with respect to mean, variability, and common contributors to support policy decision making. The methodology is applied to eight benzene pollution series measured at air quality monitors around the Houston ship channel, a major industrial port.Display Omitted
Keywords: Extreme pollution; Point source; Count regression; Zero inflation; Model based clustering;

Methane is a potent greenhouse gas, 21 times as powerful as carbon dioxide in contributing to climate change on a ton-for-ton basis. Methane, along with other short-lived forcers such as black carbon and tropospheric ozone, could play an important role in addressing global climate change. This stems both from their overall effect on climate systems, and from their concentrated impact in the short term. Because reducing emissions of such short-lived pollutants may have a large near-term impact in slowing climate change, the United States and other countries have come together to cooperate under the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants, and other partnerships such as the Global Methane Initiative. For global impact, the success of such partnerships depends on their ability to scale up project-specific emission reductions.This paper assesses options and challenges for scaling based on a case study of Russia's oil and gas sector. We examine the challenges to achieving far-reaching emission reductions, successes of companies to date, how Russia has sought to influence methane emissions through its environmental fine system, and options for helping companies achieve large-scale emission reductions in the future through simpler and clearer incentives.
Keywords: Methane mitigation; Russia; Oil and gas; Climate change; Environmental policy;

Atmospheric deposition of nitrogen and sulfur causes many deleterious effects on ecosystems including acidification and excess eutrophication. Assessments to support development of strategies to mitigate these effects require spatially and temporally continuous values of nitrogen and sulfur deposition. In the U.S., national monitoring networks exist that provide values of wet and dry deposition at discrete locations. While wet deposition can be interpolated between the monitoring locations, dry deposition cannot. Additionally, monitoring networks do not measure the complete suite of chemicals that contribute to total sulfur and nitrogen deposition. Regional air quality models provide spatially continuous values of deposition of monitored species as well as important unmeasured species. However, air quality modeling values are not generally available for an extended continuous time period. Air quality modeling results may also be biased for some chemical species. We developed a novel approach for estimating dry deposition using data from monitoring networks such as the Clean Air Status and Trends Network (CASTNET), the National Atmospheric Deposition Program (NADP) Ammonia Monitoring Network (AMoN), and the Southeastern Aerosol Research and Characterization (SEARCH) network and modeled data from the Community Multiscale Air Quality (CMAQ) model. These dry deposition values estimates are then combined with wet deposition values from the NADP National Trends Network (NTN) to develop values of total deposition of sulfur and nitrogen. Data developed using this method are made available via the CASTNET website.
Keywords: Atmospheric deposition; Nitrogen budget; Sulfur budget; Critical loads; Hybrid model;

Predictors of coarse particulate matter and associated endotoxin concentrations in residential environments by Md. Aynul Bari; Morgan MacNeill; Warren B. Kindzierski; Lance Wallace; Marie-Ève Héroux; Amanda J. Wheeler (221-230).
Exposure to coarse particulate matter (PM), i.e., particles with an aerodynamic diameter between 2.5 and 10 μm (PM10–2.5), is of increasing interest due to the potential for health effects including asthma, allergy and respiratory symptoms. Limited information is available on indoor and outdoor coarse PM and associated endotoxin exposures. Seven consecutive 24-h samples of indoor and outdoor coarse PM were collected during winter and summer 2010 using Harvard Coarse Impactors in a total of 74 Edmonton homes where no reported smoking took place. Coarse PM filters were subsequently analyzed for endotoxin content. Data were also collected on indoor and outdoor temperature, relative humidity, air exchange rate, housing characteristics and occupants' activities. During winter, outdoor concentrations of coarse PM (median = 6.7 μg/m3, interquartile range, IQR = 3.4–12 μg/m3) were found to be higher than indoor concentrations (median 3.4 μg/m3, IQR = 1.6–5.7 μg/m3); while summer levels of indoor and outdoor concentrations were similar (median 4.5 μg/m3, IQR = 2.3–6.8 μg/m3, and median 4.7 μg/m3, IQR = 2.1–7.9 μg/m3, respectively). Similar predictors were identified for indoor coarse PM in both seasons and included corresponding outdoor coarse PM concentrations, whether vacuuming, sweeping or dusting was performed during the sampling period, and number of occupants in the home. Winter indoor coarse PM predictors also included the number of dogs and indoor endotoxin concentrations. Summer median endotoxin concentrations (indoor: 0.41 EU/m3, outdoor: 0.64 EU/m3) were 4-fold higher than winter concentrations (indoor: 0.12 EU/m3, outdoor: 0.16 EU/m3). Other than outdoor endotoxin concentrations, indoor endotoxin concentration predictors for both seasons were different. Winter endotoxin predictors also included presence of furry pets and whether the vacuum had a high efficiency particulate air (HEPA) filter. Summer endotoxin predictors were problems with mice in the previous 12 months and mean indoor relative humidity levels.
Keywords: Coarse particulate matter; Endotoxin; Indoor air quality; Predictors;

Characterization of black carbon at roadside sites and along vehicle roadways in the Bangkok Metropolitan Region by Nguyen Tri Quang Hung; Seung-Bok Lee; Nguyen Thanh Hang; Jira Kongpran; Nguyen Thi Kim Oanh; Shang-Gyoo Shim; Gwi-Nam Bae (231-239).
To understand the seasonality of concentrations of traffic-related black carbon (BC) in a megacity, BC concentrations in fine particles were monitored at the roadside and on roads during both the wet and dry seasons of 2010 in the city center of Bangkok, Thailand. The BC concentration measured every 2 min by an aethalometer at the Dingdaeng roadside in the dry season was 17.9 ± 6.6 μg m−3, which was 1.6-fold higher than the value (11.5 ± 2.7 μg m−3) during the wet season. This seasonal difference could not be explained by washout by rain but was instead due to more frequent upwind conditions caused by a prevailing wind direction from the monitoring site toward the road in the wet season. When the prevailing wind direction was from the road, the average BC concentration at the roadside increased up to 30 μg m−3 during both seasons. In contrast, when the wind direction was from the site to the road, the BC concentration was reduced to the level of urban background concentrations measured inside Lumphini Park and the Dusit Zoo of Bangkok. Roadside BC concentrations were strongly correlated with NO x concentrations and elemental carbon (EC) concentrations measured in 24-h PM2.5 filter samples. Both relationships exhibited linear determination coefficients of more than 0.80, implying that NO x can be used as an indicator and an alternative for traffic-related BC at this roadside site when real-time BC monitors are not available.The average on-road BC concentration (25.5 μg m−3) was similar to the average at the roadside under downwind conditions (25.5 μg m−3) from morning to evening only. In contrast, the latter value was 1.7-fold higher than the daily average at the roadside (14.7 μg m−3) and 7.3-fold higher than the urban background level during the daytime (3.5 μg m−3). The results of this study suggest that residents who live next to major roads, pedestrians at the roadside, and drivers on the roads experience a high risk of exposure to severe levels of traffic-related air pollutants.
Keywords: Bangkok; Black carbon; Rain; Season; Traffic; Vehicle exhaust;

Annual variability in leaf area index and isoprene and monoterpene emissions during drought years in Texas by Ling Huang; Elena C. McDonald-Buller; Gary McGaughey; Yosuke Kimura; David T. Allen (240-249).
A pathway through which drought may affect estimates of emissions of isoprene and other biogenic volatile organic compounds is through changes in leaf area index (LAI), a key input parameter for biogenic emissions models. Spatial and temporal variations of an LAI product derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the relative impact of LAI versus meteorological fields and soil moisture on emissions of isoprene and monoterpenes were examined using the Model of Emissions of Gases and Aerosols from Nature (MEGAN) for four climate regions in eastern Texas. The four regions had diverse land cover and climatology during 2006–2011, years with recurring extreme to exceptional drought. Maximum monthly interannual LAI variations exceeded 20% in the North and South Central regions, but were less than 20% in East Texas and Upper Coast. Estimates of isoprene and monoterpene emissions in the two central regions were lower by as much as −24% due to significant reductions of LAI during droughts in 2006 and 2011. Maximum interannual variability in estimated monthly isoprene emissions exceeded 30%. Reductions in LAI during drought may be accompanied by increases in temperature and surface insolation that exert competing effects on biogenic emissions estimates.
Keywords: Biogenic emissions; Drought; Leaf area index; MODIS;

WRF-Chem simulations of aerosols and anthropogenic aerosol radiative forcing in East Asia by Yi Gao; Chun Zhao; Xiaohong Liu; Meigen Zhang; L. Ruby Leung (250-266).
This study aims to provide a first comprehensive evaluation of WRF-Chem for modeling aerosols and anthropogenic aerosol radiative forcing (RF, including direct, semi-direct and indirect forcing) over East Asia. Several numerical experiments were conducted from November 2007 to December 2008. Comparison between model results and observations shows that the model can generally reproduce the observed spatial distributions of aerosol concentration, aerosol optical depth (AOD) and single scattering albedo (SSA) from measurements at many sites, including the relatively higher aerosol concentration and AOD over East China and the relatively lower AOD over Southeast Asia, Korea, and Japan. The model also depicts the seasonal variation and transport of pollutions over East Asia. Particulate matter of 10 μm or less in the aerodynamic diameter (PM10), black carbon (BC), sulfate (SO4 2−), nitrate (NO3 ) and ammonium (NH4 +) concentrations are higher in spring than other seasons in Japan, which indicates the possible influence of pollutant transport from polluted area of East Asia. The model underestimates SO4 2− and organic carbon (OC) concentrations over mainland China by about a factor of 2, while overestimates NO3 concentration in autumn along the Yangtze River. The model captures the dust events at the Zhangye site in the semi-arid region of China. AOD is high over Southwest and Central China in winter and spring and over North China in winter, spring and summer while is low over South China in summer due to monsoon precipitation. SSA is lowest in winter and highest in summer. Anthropogenic aerosol RF is estimated to range from −5 to −20 W m−2 over land and −20 to −40 W m−2 over adjacent oceans at the top of atmosphere (TOA), 5–30 W m−2 in the atmosphere (ATM) and −15 to −40 W m−2 at the bottom (BOT). The warming effect of anthropogenic aerosol in ATM results from BC aerosol while the negative aerosol RF at TOA is caused by scattering aerosols such as SO4 2−, NO3 and NH4 +. Positive BC RF at TOA compensates 40–50% of the TOA cooling associated with anthropogenic aerosol.
Keywords: WRF-Chem; Anthropogenic aerosol; East Asia; Radiative forcing;

Retrospective modeling outdoor air pollution at a fine spatial scale in France, 1989–2008 by M. Bentayeb; M. Stempfelet; V. Wagner; M. Zins; S. Bonenfant; C. Songeur; O. Sanchez; A. Rosso; G. Brulfert; I. Rios; E. Chaxel; J. Virga; A. Armengaud; P. Rossello; E. Rivière; M. Bernard; F. Vasbien; R. Deprost (267-279).
Exposure to air pollution has been associated to mortality and morbidity in numerous studies. However, few studies assessed retrospectively long-term exposure at a fine spatial scale.To contribute to the assessment of long-term exposure to air pollution of participants from the French GAZEL cohort, we estimated atmospheric PM10, PM2.5, NO2, SO2, C6H6 and O3 levels at 2 km resolution over France, from 1989 to 2008.The spatiotemporal concentrations of selected air pollutants were estimated at a fine scale by combining (1) the CHIMERE chemistry-transport model (2) mesh refinement and (3) data assimilation with geostatistical analyzes. Assimilated concentrations were assigned to participants according to their residential zip codes, taking into account residential history.Despite a decreasing trend in concentrations for all pollutant concentrations, levels remained high in some French regions, especially for PM, NO2 and O3.Annual median concentrations at the cohort participants' zip code of PM10, PM2.5, NO2 and O3 were decreased from 1989 to 2008 by 27%, 29%, 40% and 16%, respectively. The largest decreases occurred for SO2 (86%) and C6H6 (85%).Validation showed high correlations between observations and final modeled data (R above 0.75 in 2007) for PM10, NO2 and O3.The modeling process enabled us to assess air pollution over 20 years (1989-2008) at a fine-geographical scale, with acceptable agreement being found between observations and models for all pollutants.
Keywords: Air pollution; Modeling; Long-term; Fine scale; France;

China has suffered from serious air pollution and CO2 emission. Challenges of emission reduction policy not only come from technology advancement, but also generate from the fact that, China has pronounced disparity between regions, in geographical and socioeconomic. How to deal with regional disparity is important to achieve the reduction target effectively and efficiently. This research conducts a spatial analysis on the emission patterns of three air pollutants named SO2, NO x and PM2.5, and CO2, in China's 30 provinces, applied with spatial auto-correlation and multi regression modeling. We further analyze the regional disparity and inequity issues with the approach of Lorenz curve and Gini coefficient. Results highlight that: there is evident cluster effect for the regional air pollutants and CO2 emissions. While emission amount increases from western regions to eastern regions, the emission per GDP is in inverse trend. The Lorenz curve shows an even larger unequal distribution of GDP/emissions than GDP/capita in 30 regions. Certain middle and western regions suffers from a higher emission with lower GDP, which reveal the critical issue of emission leakage. Future policy making to address such regional disparity is critical so as to promote the emission control policy under the “equity and efficiency” principle.
Keywords: Spatial analysis; Regional disparity; Air pollutants;

A regional mass balance model based on total ammoniacal nitrogen for estimating ammonia emissions from beef cattle in Alberta Canada by Lilong Chai; Roland Kröbel; H. Henry Janzen; Karen A. Beauchemin; Sean M. McGinn; Shabtai Bittman; Atta Atia; Ike Edeogu; Douglas MacDonald; Ruilan Dong (292-302).
Animal feeding operations are primary contributors of anthropogenic ammonia (NH3) emissions in North America and Europe. Mathematical modeling of NH3 volatilization from each stage of livestock manure management allows comprehensive quantitative estimates of emission sources and nutrient losses. A regionally-specific mass balance model based on total ammoniacal nitrogen (TAN) content in animal manure was developed for estimating NH3 emissions from beef farming operations in western Canada. Total N excretion in urine and feces was estimated from animal diet composition, feed dry matter intake and N utilization for beef cattle categories and production stages. Mineralization of organic N, immobilization of TAN, nitrification, and denitrification of N compounds in manure, were incorporated into the model to account for quantities of TAN at each stage of manure handling. Ammonia emission factors were specified for different animal housing (feedlots, barns), grazing, manure storage (including composting and stockpiling) and land spreading (tilled and untilled land), and were modified for temperature. The model computed NH3 emissions from all beef cattle sub-classes including cows, calves, breeding bulls, steers for slaughter, and heifers for slaughter and replacement. Estimated NH3 emissions were about 1.11 × 105 Mg NH3 in Alberta in 2006, with a mean of 18.5 kg animal−1 yr−1 (15.2 kg NH3–N animal−1 yr−1) which is 23.5% of the annual N intake of beef cattle (64.7 kg animal−1 yr−1). The percentage of N intake volatilized as NH3–N was 50% for steers and heifers for slaughter, and between 11 and 14% for all other categories. Steers and heifers for slaughter were the two largest contributors (3.5 × 104 and 3.9 × 104 Mg, respectively) at 31.5 and 32.7% of total NH3 emissions because most growing animals were finished in feedlots. Animal housing and grazing contributed roughly 63% of the total NH3 emissions (feedlots, barns and pastures contributed 54.4, 0.2 and 8.1% of total emissions, respectively.). Manure storage (composting and stockpiling) and land spreading contributed 23 and 14% of the total emissions, respectively. Parameters from this TAN-based mass balance model will be incorporated into the HOLOS model – a farm-level greenhouse gas calculator.
Keywords: Beef cattle; Manure management; Total ammoniacal nitrogen; Ammonia volatilization; Emission factors;

Isotopic compositions of elemental carbon in smoke and ash derived from crop straw combustion by Gang Liu; Jiuhai Li; Hui Xu; Dan Wu; Yan Liu; Hui Yang (303-308).
Six cultivars of straw for rice, maize and wheat, respectively, were burned under flaming and smoldering conditions, and carbon isotopic ratio values of elemental carbon (EC) in smoke and ash determined. The results showed that mean carbon isotopic fractionation (Δ13C) between EC in flaming and smoldering smoke from rice straw, and the starting material was −2.7‰ and −3.0‰, respectively. Moreover, the corresponding Δ13C values for EC in flaming and smoldering smoke from wheat straw were −0.1‰ and +0.4‰, respectively. Δ13C for EC in the two types of smoke from maize straw were −3.4‰ and +0.2‰, respectively. Δ13C for EC in flaming and smoldering ash from rice straw were −1.8‰ and −1.6‰ in turn. Δ13C for EC in flaming and smoldering ash from wheat straw were +0.9‰ and +2.4‰, respectively. Additionally, the ones for EC in the two types of ash from maize straw were −1.2‰ and −1.0‰, respectively. If δ13CEC values for pollutants, such as straw smoke, soot from coal and diesel-powered vehicles, and ambient PM2.5 in a region, are determined in summer and autumn, the contribution of straw burning to ambient EC is likely to be estimated with the approach of carbon isotopic mass balance.
Keywords: Crop straw; Smoke; Ash; Elemental carbon; Isotope;

A unified satellite algorithm is presented to simultaneously retrieve aerosol properties (aerosol optical depth; AOD and aerosol type) and clear-sky shortwave direct radiative effect (hereafter, DREA) over ocean. The algorithm is applied to Moderate Resolution Imaging spectroradiometer (MODIS) observations for a period from 2003 to 2010 to assess the DREA over the global ocean. The simultaneous retrieval utilizes lookup table (LUT) containing both spectral reflectances and solar irradiances calculated using a single radiative transfer model with the same aerosol input data. This study finds that aerosols cool the top-of-atmosphere (TOA) and bottom-of-atmosphere (BOA) by 5.2 ± 0.5 W/m2 and 8.3 W/m2, respectively, and correspondingly warm the atmosphere (hereafter, ATM) by 3.1 W/m2. These quantities, solely based on the MODIS observations, are consistent with those of previous studies incorporating chemical transport model simulations and satellite observations. However, the DREAs at BOA and ATM are expected to be less accurate compared to that of TOA due to low sensitivity in retrieving aerosol type information, which is related with the atmospheric heating by aerosols, particularly in low AOD conditions; consequently, the uncertainties could not be quantified. Despite the issue in the aerosol type information, the present method allows us to confine the DREA attributed only to fine-mode dominant aerosols, which are expected to be mostly anthropogenic origin, in the range from −1.1 W/m2 to −1.3 W/m2 at TOA. Improvements in size-resolved AOD and SSA retrievals from current and upcoming satellite instruments are suggested to better assess the DREA, particularly at BOA and ATM, where aerosol absorptivity induces substantial uncertainty.
Keywords: Aerosol; Direct radiative effect; Radiative forcing; Ocean; MODIS;

An air quality forecasting system is a tool for protecting public health by providing an early warning system against harmful air pollutants. In this work, the online-coupled Weather Research and Forecasting Model with Chemistry with the Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (WRF/Chem-MADRID) is used to forecast ozone (O3) and fine particles (PM2.5) concentrations over the southeastern U.S. for three O3 seasons from May to September in 2009, 2010, and 2011 and three winters from December to February during 2009–2010, 2010–2011, and 2011–2012. The forecasted chemical concentrations and meteorological variables are evaluated with observations from networks data in terms of spatial distribution, temporal variation, and discrete and categorical performance statistics. The model performs well for O3 and satisfactorily for PM2.5 in terms of both discrete and categorical evaluations but larger biases exist in PM species. The model biases are due to uncertainties in meteorological predictions, emissions, boundary conditions, chemical reactions, as well as uncertainties/differences in the measurement data used for evaluation. Sensitivity simulations show that using MEGAN online biogenic emissions and satellite-derived wildfire emissions result in improved performance for PM2.5 despite a degraded performance for O3. A combination of both can reduce normalize mean bias of PM2.5 from −18.3% to −11.9%. This work identifies a need to improve the accuracy of emissions by using dynamic biogenic and fire emissions that are dependent on meteorological conditions, in addition to the needs for more accurate anthropogenic emissions for urban areas and more accurate meteorological forecasts.
Keywords: Real-time air quality forecast; O3; PM2.5; WRF/Chem-MADRID; Online coupled model; Discrete and categorical evaluation; Satellite-derived wildfire emissions; MEGAN2;

Spatiotemporal distribution of airborne particulate metals and metalloids in a populated arid region by Gouri Prabhakar; Armin Sorooshian; Emily Toffol; Avelino F. Arellano; Eric A. Betterton (339-347).
A statistical analysis of data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network of aerosol samplers has been used to study the spatial and temporal concentration trends in airborne particulate metals and metalloids for southern Arizona. The study region is a rapidly growing area in southwestern North America characterized by high fine soil concentrations (among the highest in the United States), anthropogenic emissions from an area within the fastest growing region in the United States, and a high density of active and abandoned mining sites. Crustal tracers in the region are most abundant in the summer (April–June) followed by fall (October–November) as a result of dry meteorological conditions which favor dust emissions from natural and anthropogenic activity. A distinct day-of-week cycle is evident for crustal tracer mass concentrations, with the greatest amplitude evident in urban areas. There have been significant reductions since 1988 in the concentrations of toxic species that are typically associated with smelting and mining. Periods with high fine soil concentrations coincide with higher concentrations of metals and metalloids in the atmosphere, with the enhancement being higher at urban sites.
Keywords: Desert; Aerosol; Arizona; Arsenic; Lead; Dust;

European air quality in the 2030s and 2050s: Impacts of global and regional emission trends and of climate change by G. Lacressonnière; V.-H. Peuch; R. Vautard; J. Arteta; M. Déqué; M. Joly; B. Josse; V. Marécal; D. Saint-Martin (348-358).
A chemistry-transport model using two-way nested regional (Europe) and global domains is used to evaluate the effects of climate and emission changes on air quality over Europe for the 2030s and 2050s, by comparison with the emissions and climate of the recent past. We investigated the pollutant levels under the implementations of reduced anthropogenic emissions (NO x , SO2, etc) over Europe and, at the global scale, under the Representative Concentrations Pathways (RCP8.5) scenario produced by the Fifth Assessment Report (AR5) of IPCC. The simulations show an increase in surface ozone in northwestern Europe and a decrease in southern areas in the future horizons studied here. Over Europe, average O3 levels steadily increase with a rate of around 3 μg m−3 per decade in summer. For this pollutant, the contributions of long range transport over the Northern Hemisphere and climate changes have been assessed and appear to counterbalance and even slightly outweigh the effects of European reductions in precursors' anthropogenic emissions. The tropospheric ozone budget is found to be dominated by enhanced stratosphere–troposphere exchanges in future climate while the chemical budget is significantly reduced. Our results show that a NO x -limited chemical regime will stretch over most of Europe, including especially Western France in the future. These findings allow supporting efficient future precursor emissions abatement strategies in order to limit O3 pollution and maintain or improve air quality standards in Europe.
Keywords: European air quality; Regional modelling; Ozone; Climate change;

Quantifying contributions of local and regional NO x emission sources is an important initial step towards accurately assessing improvements in NOx emission reduction efforts. Current global NO x inventories report large uncertainties in contributions of some NO x sources, especially diffuse sources (e.g. lightning and soil NO x ). Examining the isotopic composition of NO x and its oxidation products (NO y ) is one approach to further constrain contributions from these sources. While natural and anthropogenically-derived NO x emissions are reported to have relatively distinct δ15N values that could aid NO x source apportionment studies, existing δ15N–NO x source data is limited and variable collection approaches have been employed. To build on existing δ15N–NO x source data, inexpensive and easily deployable passive samplers were used to collect nitrogen dioxide (NO2) emissions and its oxidation product, nitric acid (HNO3), from multiple emission sources including livestock waste, fertilized soils, and vehicles. The resulting isotope data provides evidence that passive samplers can be used across a range of environmental conditions with widely varying NO2 concentrations and NO2 isotopic compositions. Using this approach, we report the first δ15N and δ18O–NO2 of livestock waste emissions, as well as the first measurements of δ18O–NO2 from biogenic soil and vehicle emissions. We observe the highest δ15N–NO2 values to date of vehicle emissions and investigate potential fractionations associated with oxidation and equilibrium processes. The large differences reported here between δ15N–NO2 values from fossil fuel-based sources and microbially-produced sources allows for identification and possible quantification of source contributions to ambient NO x concentrations.
Keywords: Nitrogen dioxide; NO x ; Isotope; Emission;

Theoretical study on mechanisms and pathways of the CF3O2 + ClO reaction by Yizhen Tang; Haofen Sun; Jingyu Sun; Yunju Zhang; Rongshun Wang (367-375).
The mechanisms and reaction pathways for the atmospheric CF3O2 + ClO reaction have been investigated by quantum chemistry methods. The CCSD(T)/6-311++G(2d,2p)//B3LYP/6-311++G(d,p) results show that only the singlet potential energy surface (PES) is of importance for the title reaction, and the dominant products included CF3OOOCl and CF3O + ClOO under the normal atmospheric conditions (T < 300 K). While other products such as CF3OClO2, CF3OOClO, CF3O + OClO and CF2O + FClO2 are negligible. TDDFT (Time Dependent Density Functional Theory) calculations indicate that CF3OOClO and CF3OClO2 will undergo photolysis in the troposphere, and CF3OOOCl will photolyze in the stratosphere.
Keywords: CF3O2; Atmospheric reaction; Chlorinemonoxide; Photolysis;

Halogenated volatile organic compounds in chlorine-bleach-containing household products and implications for their use by Mustafa Odabasi; Tolga Elbir; Yetkin Dumanoglu; Sait C. Sofuoglu (376-383).
It was recently shown that substantial amounts of halogenated volatile organic compounds (VOCs) are formed in chlorine-bleach-containing household products as a result of reactions of sodium hypochlorite with organic product components. Use of these household products results in elevated indoor air halogenated VOC concentrations. Halogenated VOCs in several chlorine-bleach-containing household products (plain, n = 9; fragranced, n = 4; and surfactant-added, n = 29) from Europe and North America were measured in the present study. Chloroform and carbon tetrachloride were the dominating compounds having average concentrations of 9.5 ± 29.0 (average ± SD) and 23.2 ± 44.3 (average ± SD) mg L−1, respectively. Halogenated VOC concentrations were the lowest in plain bleach, slightly higher in fragranced products and the highest in the surfactant-added products. Investigation of the relationship between the halogenated VOCs and several product ingredients indicated that chlorinated VOC formation is closely related to product composition. Indoor air concentrations from the household use of bleach products (i.e., bathroom, kitchen, and hallway cleaning) were estimated for the two dominating VOCs (chloroform and carbon tetrachloride). Estimated indoor concentrations ranged between 0.5 and 1030 (34 ± 123, average ± SD) μg m−3 and 0.3–1124 (82 ± 194, average ± SD) μg m−3 for chloroform and carbon tetrachloride, respectively, indicating substantial increases compared to background. Results indicated that indoor air concentrations from surfactant-added products were significantly higher (p < 0.01) than other categories. The highest concentrations were from the use of surfactant-added bleach products for bathroom cleaning (92 ± 228 and 224 ± 334 μg m−3, average ± SD for chloroform and carbon tetrachloride, respectively). Associated carcinogenic risks from the use of these products were also estimated. The risk levels may reach to considerably high levels for a significant portion of the population especially for those steadily using the surfactant-added bleach products. Based on the results of the present study, it could be recommended that if possible the use of chlorine bleach containing household products should be avoided. If they are to be used, plain products should be preferred since the chlorinated VOC content increase with the number and amount of additives.Display Omitted
Keywords: Chlorine bleach; Chloroform; Carbon tetrachloride; Indoor air; Inhalation exposure;

Indoor concentrations of fine (PM2.5: aerodynamic diameter ≤ 2.5) and inhalable (PM10: aerodynamic diameter ≤ 10 μm) particles and its associated toxic metals are of concern now-a-days due to its effects on human health and environment. PM10 and PM2.5 samples were collected from indoor microenvironments on glass fiber and PTFE filter paper using low volume air sampler in Pune. The average concentration of PM2.5 and PM10 were 89.7 ± 43.2 μg m−3 and 138.2 ± 68.2 μg m−3 at urban site while it was 197.5 ± 84.3 and 287 ± 92 μg m−3 at rural site. Trace metals such as Cd, Co, Cr, Cu, Fe, Mn, Pb, Sb and Zn in particulate matter were estimated by ICP–AES. Concentrations of crustal metals were found to be higher than the carcinogenic metals in both the microenvironments. On the contrary the soluble and bio-availability fraction of carcinogenic metals were found higher thus it may cause the higher risk to human health. Therefore, cancer risk assessment of carcinogenic metals; Cr, Ni and Cd was calculated. Among the carcinogenic metals, Ni showed highest cancer risk in indoor PM. The higher cancer risk assessment of Ni has been supported by In-silico study which suggested that Ni actively formed co-ordination complex with histone proteins (i.e. H3–Ni/H4–Ni) by maintaining strong hydrogen bonding interactions with Asp and Glu residues of nucleosomal proteins. Present In-silico study of Ni-histone complexes will help to emphasize the possible role of Asp and Glu residues in DNA methylation, deacetylation and ubiquitinations of nucleosomal proteins. Hence, this study could pave the way to understand the structural consequence of Ni in nucleosomal proteins and its impact on epigenetic changes which ultimately cause lung and nasal cancer.
Keywords: IAQ; PM concentration; Trace metals; Metal toxicity; Health risk assessment; In-silico study;

Nitrous oxide emissions from soil due to urine deposition by grazing cattle in Brazil by A.S. Barneze; A.M. Mazzetto; C.F. Zani; T. Misselbrook; C.C. Cerri (394-397).
Urine deposition to the soil can result in nitrous oxide emissions through the microbial processes of nitrification and denitrification. The objective of this experiment was to estimate N2O emissions from urine depositions to grassland during summer in Southeast Brazil. A field experiment was conducted in which N2O emissions were measured from known volumes of urine applied to the soil, using the static chamber method. Measurements continued for one month after application. Application of urine to soil increased N2O fluxes compared to those from the control site. There were two significant N2O emission peaks for the urine treatment at around the 3rd and 13th days after application, the first in response to the urine application and the second most likely in response to a rainfall event. The N2O emissions accounted for 0.2% of the applied urine N. These represent the first data relating to emissions from urine depositions by grazing cattle in Brazil. Further measurements across a range of soil and weather conditions in Brazil are required to develop national and regional specific emission factors for inventory development.
Keywords: Livestock; GHG emissions; Liquid manure; Pasture; N2O emission factor; Nitrogen;

To design and implement an effective emission control strategy for black carbon (BC), the locations and strength of BC sources must be identified. Lack of accurate source information from the Russian Federation has created difficulty for a range of research and policy activities in the Arctic because Russia occupies the largest landmass in the Arctic Circle. A project was initiated to resolve emission sources of BC in the Russian Federation by using the Potential Source Contribution Function (PSCF). It used atmospheric BC data from two Arctic sampling stations at Alert Nunavut, Canada, and Tiksi Bay, Russia. The geographical regions of BC emission sources in Russia were identified and summarized as follows: (1) a region surrounding Moscow, (2) regions in Eurasia stretching along the Ural Mountains from the White Sea to the Black Sea, and (3) a number of scattered areas from western Siberia to the Russian Far East. Particulate potassium ions, non-marine sulfate, and vanadium were used to assist in resolving the source types: forest fire/biomass burning, coal-fired power plant, and oil combustion. Correlating these maps with the BC map helped to resolve source regions of BC emissions and connect them to their corresponding source types. The results imply that a region south of Moscow and another north of the Ural Mountains could be significant BC sources, but none of the grid cells in these regions could be linked to forest fires, oil combustion, or coal-fired power plants based on these three markers.
Keywords: Arctic; Atmospheric aerosol; Black carbon; Emission sources; HYSPLIT; Russia;

Active and passive smoking – New insights on the molecular composition of different cigarette smoke aerosols by LDI–FTICRMS by Sébastien Schramm; Vincent Carré; Jean-Luc Scheffler; Frédéric Aubriet (411-420).
The aerosol generated when a cigarette is smoked is a significant indoor contaminant. Both smokers and non-smokers can be exposed to this class of pollutants. Nevertheless, they are not exposed to the same kind of smoke. The active smoker breathes in the mainstream smoke (MSS) during a puff, whereas the passive smoker inhales not only the smoke generated by the lit cigarette between two puffs (SSS) but also the smoke exhaled by active smokers (EXS). The aerosol fraction of EXS has until now been poorly documented; its composition is expected to be different from MSS. This study aims to investigate the complex composition of aerosol from EXS to better understand the difference in exposure between active and passive smokers. To address this, the in-situ laser desorption ionisation Fourier transform ion cyclotron mass spectrometry (LDI–FTICRMS) was used to characterise the aerosol composition of EXS from two different smokers. Results clearly indicated many similarities between EXS samples but also significant differences with MSS and SSS aerosol. The comparison of MSS and EXS aerosol allowed the chemicals retained by the active smoker's lungs to be identified, whereas the convolution of the EXS and SSS aerosol compositions were considered relevant to the exposition of a passive smoker. As a consequence, active smokers are thought to be mainly exposed to polar and poorly unsaturated oxygenated and nitrogenated organics, compared with poorly oxygenated but highly unsaturated compounds in passive smokers.Display Omitted
Keywords: Cigarette smoke; Active smoker; Passive smoker; Mass spectrometry; Aerosol; LDI–FTICRMS;

Mercury enrichment and its effects on atmospheric emissions in cement plants of China by Fengyang Wang; Shuxiao Wang; Lei Zhang; Hai Yang; Qingru Wu; Jiming Hao (421-428).
The cement industry is one of the most significant anthropogenic sources of atmospheric mercury emissions worldwide. In this study of three typical Chinese cement plants, mercury in kiln flue gas was sampled using the Ontario Hydro Method (OHM), and solid samples were analyzed. Particulate matter recycling, preheating of raw materials, and the use of coal and flue gas desulfurization derived gypsum contributed to emissions of Hg in the air and to accumulation in cement. Over 90% of the mercury input was emitted into the atmosphere. Mercury emission factors were 0.044–0.072 g/t clinker for the test plants. The major species emitted into the atmosphere from cement plants is oxidized mercury, accounting for 61%–91% of the total mercury in flue gas. The results of this study help improve the accuracy of the mercury emission inventory in China and provide useful information for developing mercury controls.
Keywords: Cement plant; Mercury enrichment; Atmospheric emissions; Mercury speciation;

Relationship between column-density and surface mixing ratio: Statistical analysis of O3 and NO2 data from the July 2011 Maryland DISCOVER-AQ mission by Clare M. Flynn; Kenneth E. Pickering; James H. Crawford; Lok Lamsal; Nickolay Krotkov; Jay Herman; Andrew Weinheimer; Gao Chen; Xiong Liu; James Szykman; Si-Chee Tsay; Christopher Loughner; Jennifer Hains; Pius Lee; Russell R. Dickerson; Jeffrey W. Stehr; Lacey Brent (429-441).
To investigate the ability of column (or partial column) information to represent surface air quality, results of linear regression analyses between surface mixing ratio data and column abundances for O3 and NO2 are presented for the July 2011 Maryland deployment of the DISCOVER-AQ mission. Data collected by the P-3B aircraft, ground-based Pandora spectrometers, Aura/OMI satellite instrument, and simulations for July 2011 from the CMAQ air quality model during this deployment provide a large and varied data set, allowing this problem to be approached from multiple perspectives. O3 columns typically exhibited a statistically significant and high degree of correlation with surface data (R 2 > 0.64) in the P-3B data set, a moderate degree of correlation (0.16 < R 2 < 0.64) in the CMAQ data set, and a low degree of correlation (R 2 < 0.16) in the Pandora and OMI data sets. NO2 columns typically exhibited a low to moderate degree of correlation with surface data in each data set. The results of linear regression analyses for O3 exhibited smaller errors relative to the observations than NO2 regressions. These results suggest that O3 partial column observations from future satellite instruments with sufficient sensitivity to the lower troposphere can be meaningful for surface air quality analysis.
Keywords: Ozone; Nitrogen oxides; DISCOVER-AQ; Column–surface relationship; Aircraft measurement campaign; Measurement-model comparison;

Chemical characteristics and source apportionment of PM2.5 during the harvest season in eastern China's agricultural regions by Jianfeng Li; Yu Song; Yi Mao; Zhichun Mao; Yusheng Wu; Mengmeng Li; Xin Huang; Qichao He; Min Hu (442-448).
To determine the contribution of the open burning of wheat straw residues to local PM2.5 during the harvest season of June 2013, PM2.5 was sampled in an agricultural region in eastern China. The sampling site was approximately 1 km from the nearest wheat field. Chemical compositions were analyzed, and source apportionment was undertaken using the positive matrix factorization model. The average PM2.5 concentration was 110.7 μg/m3, containing 36.4 μg/m3 organics, 7.3 μg/m3 EC, 6.0 μg/m3 potassium (K) and 4.9 μg/m3 chloride ion (Cl). The sampling period was divided into three phases: the pre-local-burning phase (Phase 1), the local-burning phase (Phase 2) and the post-local-burning phase (Phase 3). In Phase 2, the concentrations of PM2.5 and the organics, EC, K and Cl in PM2.5 were 163.6 μg/m3, 59.0 μg/m3, 12.2 μg/m3, 11.0 μg/m3 and 10.8 μg/m3, respectively, which were all remarkably higher than in both Phase 1 and Phase 3. Eight sources of PM2.5 were determined, including two types of wheat residue burning sources, which showed a significant difference in Cl content. The atmospheric relative humidity (RH) and the aging process of PM2.5 might be the causes: only fresh particulate emissions from wheat residue burning could feature high-concentration Cl under high RH conditions. In Phase 2, wheat residue burning contributed 51.3% of PM2.5, 75.8% of OC, 74.5% of EC, 90.1% of K and 104.1% of Cl. These percentages were lower in Phases 1 and 3 than in Phase 2. Wheat residue burning caused such severe air pollution that it's necessary to prohibit the open burning of crop residues in order to protect public health and the environment.
Keywords: Wheat residue burning; Harvest season; PM2.5; Chemical compositions; Source apportionment;

In India, of the 210 GW electricity generation capacity, 66% is derived from coal, with planned additions of 76 GW and 93 GW during the 12th and the 13th five year plans, respectively. Atmospheric emissions from the coal-fired power plants are responsible for a large burden on human health. In 2010–11, 111 plants with an installed capacity of 121 GW, consumed 503 million tons of coal, and generated an estimated 580 ktons of particulates with diameter less than 2.5 μm (PM2.5), 2100 ktons of sulfur dioxides, 2000 ktons of nitrogen oxides, 1100 ktons of carbon monoxide, 100 ktons of volatile organic compounds, and 665 million tons of carbon dioxide. These emissions resulted in an estimated 80,000 to 115,000 premature deaths and 20.0 million asthma cases from exposure to PM2.5 pollution, which cost the public and the government an estimated INR 16,000 to 23,000 crores (USD 3.2 to 4.6 billion). The emissions were estimated for the individual plants and the atmospheric modeling was conducted using CAMx chemical transport model, coupled with plume rise functions and hourly meteorology. The analysis shows that aggressive pollution control regulations such as mandating flue gas desulfurization, introduction and tightening of emission standards for all criteria pollutants, and updating procedures for environment impact assessments, are imperative for regional clean air and to reduce health impacts. For example, a mandate for installation of flue gas desulfurization systems for the operational 111 plants could reduce the PM2.5 concentrations by 30–40% by eliminating the formation of the secondary sulfates and nitrates.
Keywords: Environmental regulations; Particulates; Sulfates; Flue gas desulfurization; CAMx; Health impacts;

Subway platform air quality: Assessing the influences of tunnel ventilation, train piston effect and station design by T. Moreno; N. Pérez; C. Reche; V. Martins; E. de Miguel; M. Capdevila; S. Centelles; M.C. Minguillón; F. Amato; A. Alastuey; X. Querol; W. Gibbons (461-468).
A high resolution air quality monitoring campaign (PM, CO2 and CO) was conducted on differently designed station platforms in the Barcelona subway system under: (a) normal forced tunnel ventilation, and (b) with daytime tunnel ventilation systems shut down. PM concentrations are highly variable (6–128 μgPM1 m−3, 16–314 μgPM3 m−3, and 33–332 μgPM10 m−3, 15-min averages) depending on ventilation conditions and station design. Narrow platforms served by single-track tunnels are heavily dependent on forced tunnel ventilation and cannot rely on the train piston effect alone to reduce platform PM concentrations. In contrast PM levels in stations with spacious double-track tunnels are not greatly affected when tunnel ventilation is switched off, offering the possibility of significant energy savings without damaging air quality. Sampling at different positions along the platform reveals considerable lateral variation, with the greatest accumulation of particulates occurring at one end of the platform. Passenger accesses can dilute PM concentrations by introducing cleaner outside air, although lateral down-platform accesses are less effective than those positioned at the train entry point. CO concentrations on the platform are very low (≤1 ppm) and probably controlled by ingress of traffic-contaminated street-level air. CO2 averages range from 371 to 569 ppm, changing during the build-up and exchange of passengers with each passing train.
Keywords: Rail subway; Piston effect; PM; CO2; CO; Barcelona;

Nitrous oxide fluxes from three forest types of the tropical mountain rainforests on Hainan Island, China by Zhenzhi Bai; Gang Yang; Huai Chen; Qiuan Zhu; Dexiang Chen; Yide Li; Xu Wang; Zhongmin Wu; Guangyi Zhou; Changhui Peng (469-477).
Tropical rainforest soil is an important source of atmospheric nitrous oxide (N2O). However, there is still considerable uncertainty about the spatial and temporal variability of N2O fluxes. To understand these fluxes, we quantified the annual N2O emissions from three tropical mountain rainforests (primary mountain rainforest, PMR; secondary mountain rainforest, SMR; and Podocarpus imbricatus plantation, PIP) in the Jianfengling National Natural Reserve on Hainan Island, China. The average of N2O emissions in this area was 2.52 ± 0.33 kg N–N2O ha−1 yr−1 (3.52 kg N–N2O ha−1 yr−1 in the wet season and 1.62 kg N–N2O ha−1 yr−1 in the dry season) during our study period, with highly seasonal variations. The mean N2O emission rates were significantly higher during the wet season (68% of the total average) than the dry season (32% of the total average) (P < 0.05). PIP had the highest N2O emission rate at 3.49 ± 0.61 kg N–N2O ha−1 yr−1 (4.74 kg N–N2O ha−1 yr−1 in the wet season and 2.32 kg N–N2O ha−1 yr−1 in the dry season), followed by SMR at 3.03 ± 0.64 kg N–N2O ha−1 yr−1 (4.16 kg N–N2O ha−1 yr−1 in the wet season and 1.97 kg N–N2O ha−1 yr−1 in the dry season), and then PMR at 1.53 ± 0.49 kg N–N2O ha−1 yr−1 (2.21 kg N–N2O ha−1 yr−1 in the wet season and 0.94 kg N–N2O ha−1 yr−1 in the dry season). We observed a significant Gaussian relationship between the N2O fluxes and soil temperature for SMR and PIP but no significant relationship in PMR. There was a significant exponential relationship between the N2O fluxes and water filled pore space (WFPS) in SMR and PIP but not in PMR.
Keywords: Tropical mountain rainforest; N2O fluxes; Water filled pore space; Soil temperature; Spatial and temporal variability;

Methane emissions from temperate herbaceous peatland in the Sanjiang Plain of Northeast China by Xiaoyan Zhu; Changchun Song; Yuedong Guo; Xiaoxin Sun; Xinhou Zhang; Yuqing Miao (478-483).
Peatlands are the significant source of atmospheric methane (CH4), which is produced during peat accumulation. In this study, we investigated CH4 emissions over two growing seasons from a Carex lasiocarpa-dominated peatland in the Sanjiang Plain in China using the static chamber technique. We also investigated the environmental factors controlling emissions during the two years of study, 2012 and 2013. CH4 emissions ranged from 0.07 to 56.01 mg CH4–C m−2 h−1 with mean values of 7.33 ± 1.65 mg C m−2 h−1, showing significant temporal patterns in both years with peak values in early June and middle August respectively. Variations in water table, soil temperature at 25 cm depth and soil's water-filled pore space together explained 66.7% of the observed temporal variation of CH4 fluxes by the step-wise regression. Rapid and short-lived precipitation events might have no immediate influence on CH4 emissions, which primarily depended on the actual soil aeration and moisture conditions. A simple relationship between single parameter and CH4 fluxes would be overruled once the water table dropped below the critical threshold for CH4 release. The amount of CH4 emitted from the herbaceous peatland in the Sanjiang Plain during the growing season was about 6.93 × 1012 mg C. Our results suggested that the herbaceous peatland in the Sanjiang Plain is an important source of atmospheric CH4.
Keywords: CH4 emissions; Accurate prediction; Peatland; Water table; Time lag;

Sources of polycyclic aromatic hydrocarbons in PM2.5 over the East China Sea, a downwind domain of East Asian continental outflow by Fengwen Wang; Tian Lin; Yuanyuan Li; Tianyi Ji; Chuanliang Ma; Zhigang Guo (484-492).
A receptor site in the East China Sea (ECS), ∼66 km off the shore of Shanghai, was used to investigate the seasonally atmospheric transport of land-based PAHs. Positive matrix factorization (PMF) modeling and back trajectories were performed to apportion the sources of the 16 USEPA priority PAHs (16 PAHs). In the process, three episodes were observed in all seasons except summer. These episodes provided additional insight to the transport mechanisms of these air pollutants in this most developed region of China. The average concentrations (in ng/m3) of PAHs in PM2.5 in fall, winter, spring and summer were 5.26 ± 5.36, 10.41 ± 8.58, 3.93 ± 2.31 and 0.97 ± 0.25, respectively, and with an annual average of 5.24 ± 5.81. Low molecular weight (LMW) PAHs (i.e., 2 ∼ 3-ring) was a dominant contributor for the 16 PAHs in PM2.5 over the ECS (36.2%), especially in summer (55.6%). The source apportionment by PMF analysis indicated that, based on yearly average, vehicular emission (27.0%) and coal combustion (24.5%) were the two major sources of PAHs, followed by biomass burning (16.5%), petroleum residue (16.3%) and air–surface exchange (15.7%). The highest source contributor for PAHs in fall and winter was coal combustion (30.5%) and vehicular emission (34.5%), respectively; while in spring and summer, the air–surface exchange contributed the most (27.1% and 59.5%, respectively). The specific composition patterns of 16 PAHs and PMF modeling results manifested that the air–sea exchange could be a potential source for the LMW PAHs in PM2.5 over the ECS, especially in warm season.
Keywords: Sources; PAHs; PMF; East Asian continental outflow; The East China Sea;

Increasing emissions from fossil-fuel, biomass burning, land use changes and industrial growth have led to rapid increase in the atmospheric concentrations of carbonaceous species over many cities in India. The present paper deals with the results obtained from year long (2012–13) observations conducted at a tropical urban location, Pune in southwestern India on Organic and Elemental Carbon as well as Black Carbon; using the Sunset OCEC Analyzer and Aethalometer, respectively. The average mass concentrations of OC and EC were in the order of winter > post-monsoon > summer > monsoon. Mean annual OC/EC ratio was found to be 2.4 ± 1.1 during the study period, suggesting the presence of secondary organic carbon (SOC). Estimated SOC was found to form 47% of OC mass concentration. OC and EC were also significantly well correlated (r = 0.95, p < 0.0001) to each other, indicating towards common combustion sources. The primary organic carbon (POC) dominated over SOC and EC in post-monsoon and winter seasons indicating impact of anthropogenic burning activity, enhanced by prevailing meteorological conditions as well as that of long range transport. Mean annual POC + EC/TC ratio was 0.69 indicating that more than 2/3 of TC is formed from combustion sources. Thermally derived EC and optically derived BC correlated very well (r = 0.98, p < 0.0001). A new concept e.g. Effective carbon ratio (ECR) is suggested to better assess the scattering/absorptive nature and probable source identification of carbonaceous aerosols in place of conventional OC/EC ratio.
Keywords: Organic and elemental carbon; OC/EC ratio; Primary and secondary organic carbon; Effective carbon ratio;

The main aim of this study was to determine and discuss the aggregate of energy use and greenhouse gas emission (CO2, N2O, and CH4) for sugar beet agroecosystems in western of Iran. For this propose data was collected by using questionnaires and face to face interview with 50 farmers. Results showed that total inputs and output energy were 49517.2 and 1095360.0 MJ ha−1, respectively. Energy use efficiency was 22.12. Total CO2, N2O and CH4 emissions due to chemical inputs were 2668.35, 22.92 and 3.49 kg, respectively. In sugar beet farms total global warming potential (GWPs) was 9847.77 kg CO2eq ha−1. In terms of CO2 equivalents, 27% of the GWPs come from CO2, 72% from N2O, and 1% from CH4. In this research input and output carbon were 29340.0 and 2678.6 kg C ha−1, respectively. Hence, carbon efficiency ratio was 10.95.
Keywords: Energy use efficiency; Carbon efficiency ratio; Greenhouse effect; Global warming potential (GWP);

Effects of Asian dust on daily cough occurrence in patients with chronic cough: A panel study by Tomomi Higashi; Yasuhiro Kambayashi; Noriyuki Ohkura; Masaki Fujimura; Satoshi Nakai; Yasushi Honda; Kiyofumi Saijoh; Kazuichi Hayakawa; Fumihisa Kobayashi; Yoshimasa Michigami; Anyenda Enoch Olando; Yoshiaki Hitomi; Hiroyuki Nakamura (506-513).
Asian dust, known as kosa in Japanese, is a major public health concern. In this panel study, we evaluated the effects of exposure to kosa on daily cough occurrence. The study subjects were 86 patients being treated for asthma, cough variant asthma, or atopic cough in Kanazawa University Hospital from January 2011 to June 2011. Daily mean concentrations of kosa and spherical particles were obtained from light detection and ranging (LIDAR) measurements, and were categorized from Grade 1 (0 μg/m3) to 5 (over 100 μg/m3). The association between kosa and cough was analyzed by logistic regression with a generalized estimating equation. Kosa effects on cough were seen for all Grades with potential time lag effect. Particularly at Lag 0 (the day of exposure), a dose–response relationship was observed: the odds ratios for Grades 2, 3, 4, and 5 above the referent (Grade 1) were 1.111 (95% confidence interval (CI): 0.995–1.239), 1.171 (95% CI: 1.006–1.363), 1.357 (95% CI: 1.029–1.788), and 1.414 (95% CI: 0.983–2.036), respectively. Among the patients without asthma, the association was higher: the odds ratios for Grades 2, 3, 4 and 5 were 1.223 (95% CI: 0.999–1.497), 1.309 (95% CI: 0.987–1.737), 1.738 (95% CI: 1.029–2.935) and 2.403 (95% CI: 1.158–4.985), respectively. These associations remained after adjusting for the concentration of spherical particles or particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5). Our findings demonstrate that kosa is an environmental factor which induces cough in a dose–response relationship.
Keywords: Asian dust; Kosa; Chronic cough; Daily cough symptom; PM2.5;

A yearlong study of water-soluble organic carbon in Beijing I: Sources and its primary vs. secondary nature by Zhenyu Du; Kebin He; Yuan Cheng; Fengkui Duan; Yongliang Ma; Jiumeng Liu; Xiaolu Zhang; Mei Zheng; Rodney Weber (514-521).
Sources and properties of water-soluble organic carbon (WSOC) were investigated based on fine particulate matter (PM2.5) samples collected in Beijing during a thirteen month campaign. The WSOC to OC ratios averaged 45.9% annually and were substantially higher in summer compared with the other seasons. WSOC exhibited strong correlation with secondary components such as secondary organic aerosol estimated by the elemental carbon (EC)-tracer method and inorganic ions (e.g., sulfate and nitrate), whereas the correlation between WSOC and EC was much weaker, suggesting that WSOC should be dominated by secondary species. Moreover, the trend of the WSOC to EC ratio was found to coincide with that of relative humidity during winter, spring and fall. High WSOC/EC ratio in February indicates high humidity could enhance the formation potential of WSOC in winter. Sources of WSOC were further investigated by a receptor model (Positive Matrix Factorization model). The apportionment results suggested that biomass burning contributed about 40% of WSOC while about 54% of WSOC was associated with oxalate and sulfate, whereas a primary factor was responsible for only 6% of WSOC also demonstrating that primary emissions are not the main source of WSOC.
Keywords: WSOC; SOA; Biomass burning; Source apportionment;

Assessment of fine and sub-micrometer aerosols at an urban environment of Argentina by Mariana Achad; María Laura López; Sergio Ceppi; Gustavo G. Palancar; Germán Tirao; Beatriz M. Toselli (522-532).
Bulk aerosol samples collected during 2010 and 2011 at one receptor site in Córdoba City, Argentina, have been quantitatively analyzed to determine aerosol elemental composition by using SR-XRF. A receptor model analysis has been applied to ambient PM2.5 measurements. Four sources have been identified being their contributions: traffic: (13 ± 2) μg m−3, SO 4 2 − /combustion processes, including biomass burning: (15 ± 1) μg m−3, mineral dust: (7 ± 2) μg m−3 and industry: (8 ± 1) μg m−3. Source identification was carried out by inspection of key species in source profiles, seasonality of source contributions, comparison with literature data and the knowledge of the city; for the biomass burning contribution the MODIS burned area daily product was used to confirm wildfire events along the year. In addition, from May to August 2011, aerosols were collected in two additional size fractions (PM0.25–0.5, PM0.5–1) to investigate the toxic metal contributions to the finer fractions. An important result of this work is that toxic metals make an important contribution to the finest (PM0.25–0.5) size fraction. The results of the present analysis can help to demonstrate to local and national authorities the urgent need to carry out emission inventories, to implement air quality monitoring systems and to set regulations for PM2.5.
Keywords: PM2.5, PM0.5–1, and PM0.25–0.5; Chemical elements; PMF model; Synchrotron radiation X-Ray fluorescence; Córdoba city;

We have studied the effects of application of different nitrification inhibitors on methane (CH4) and nitrous oxide (N2O) emissions from rice paddy and associated soil chemical and biological dynamics during wet and dry seasons of rice crop in a tropical climate of eastern India. The experiment consisted of four treatments viz. (i) Prilled urea amended control (ii) urea + Dicyandiamide (DCD), (iii) urea + Nimin and (iv) urea + Karanjin. CH4 emission was significantly higher from the DCD (372.36 kg ha−1) and Karanjin (153.07 kg ha−1) applied plots during the wet and dry season, respectively. N2O emission was significantly inhibited in the Nimin applied plots during both seasons (69% and 85% over control during wet season and dry season respectively). CH4 and N2O emissions per Mg of rice grain yield were lowest from the Nimin applied plots during both seasons. Global warming potential (GWP) of the plot treated with DCD (13.93) was significantly higher during the experimental period. CH4 production potential was significantly higher from the nitrification inhibitor applied plots compared to control. While, CH4 oxidation potential followed the order; urea + Nimin > urea + Karanjin > urea + DCD > control. Application of Nimin significantly increased the methanotrophic bacterial population in the soil during the maximum tillering to flowering stage and may be attributed to low CH4 emission from the plots. Denitrification enzyme activity (DEA) of the soil was significantly low from the Nimin and Karanjin applied plots. Results suggest that apart from being potent nitrification inhibitors, Nimin and Karanjin also have the potential to reduce the denitrification activity in the soil. This in turn, would reduce N2O emission from flooded paddy where both nitrification and denitrification processes causes N2O emission.
Keywords: Rice paddy; Methane; Nitrous oxide; DCD; Nimin; Karanjin;

The heaviest particulate air-pollution episodes occurred in northern China in January, 2013: Insights gained from observation by Dongsheng Ji; Liang Li; Yuesi Wang; Junke Zhang; Mengtian Cheng; Yang Sun; Zirui Liu; Lili Wang; Guiqian Tang; Bo Hu; Na Chao; Tianxue Wen; Hongyan Miao (546-556).
A comprehensive measurement was conducted to analyze the heaviest air pollution episodes, which occurred in January 2013 with the focus on particulate characterization and haze. Based on observation, five heavy pollution episodes were recorded, whose frequencies are far greater than in other years. Among the heavy pollution episodes, two distinct severe regional PM2.5 (particulate matter (PM) with an aerodynamic diameter ≤2.5 μm) pollution episodes were selected for investigation. One episode is characterized by an explosive growth in PM2.5 concentrations within several hours, which is mainly caused by the high local emission under stagnant conditions; the other episode is characterized by four-day consecutive increases in PM2.5 concentrations, which is largely attributed to a combination of slow regional transport and local accumulation. The PM compositions and concentrations including PM2.5, PM1 (PM with an aerodynamic diameter ≤1 μm), nitrate, sulfate, ammonium, organic carbon (OC) and elemental carbon (EC) as well as main gaseous precursor concentrations are analyzed in Beijing during the two episodes. Rapid gas-to-particle conversion, coagulation and collision of particles are discussed under high emission and stagnant weather conditions. High sulfur and nitrogen oxidation ratios were found, suggesting that additional production of sulfate and nitrate occurred during the pollution episodes. In addition, high levels of secondary particles were transported from surrounding regions via vertical mixing and horizontal transport during the polluted days. Notably, the stationary source is still a major contributor to the pollution episodes. Clear evidence is presented indicating that the secondary formation of particulate was one important mechanism in the formation of the heavy pollution episodes. To control the air pollution effectively, more stringent restriction measures on the SO2 and NO x emissions should be strictly executed at the regional scale.
Keywords: Air pollution episodes; PM1; PM2.5; Northern China; Sulfate; Nitrate; OC; EC;

In-use measurement of the activity, fuel use, and emissions of front-loader refuse trucks by Gurdas S. Sandhu; H. Christopher Frey; Shannon Bartelt-Hunt; Elizabeth Jones (557-565).
Field measurements were made for six front-loader refuse trucks for over 560 miles (901 km) and 47 h of operation using a portable emissions measurement system, electronic control unit data logger, and global positioning system receivers. Daily activity, fuel use rates, and emission rates are quantified in terms of operating mode bins defined by the U.S. Environmental Protection Agency for the MOVES emission factor model. On average, 44 (±4) percent of time was spent at idle, 5 (±1) percent braking or decelerating, 11 (±2) percent coasting, 23 (±3) percent cruising or accelerating at low speed (up to 25 mph, 40.2 kmph), 10 (±2) percent cruising or accelerating at moderate speed (25–50 mph, 40.2 to 80.4 kmph), and 7 (±3) percent cruising or accelerating at high speed (50 mph, 80.4 kmph or higher). Fuel use and emission rates varied among operating modes by factors of 6–24. The estimated daily activity cycle average fuel economy ranges from 2.3 to 3.2 mpg (0.98–1.4 kmpl). The PM emission rates for trucks with diesel particulate filters are 98 percent lower compared to those without. Variation in truck weight lead to differences in average fuel use and emission rates of 20 percent or less, except for hydrocarbons. The variation in the empirically-based daily activity cycle average rates were highly correlated with MOVES estimates, except for hydrocarbons. The data collected here are useful for quantifying daily activity specific to front-loaders, and for developing fuel use and emission estimates and models for this type of vehicle.
Keywords: Diesel refuse truck; Duty cycle; Exhaust emissions; Nitrogen oxides; Particulate matter; MOVES;

Small-scale spatial variations of gaseous air pollutants – A comparison of path-integrated and in situ measurement methods by Hong Ling; Klaus Schäfer; Jinyuan Xin; Min Qin; Peter Suppan; Yuesi Wang (566-575).
Traffic emissions are a very important factor in Beijing's urban air quality. To investigate small-scale spatial variations in air pollutants, a campaign was carried out from April 2009 through March 2011 in Beijing. DOAS (differential optical absorption spectroscopy) systems and in situ instruments were used. Atmospheric NO, NO2, O3 and SO2 mixing ratios were monitored. Meanwhile, HCHO mixing ratios were measured by two different DOAS systems. Diurnal variations of these mixing ratios were analysed. Differences between the path-integrated and in situ measurements were investigated based on the results from the campaign. The influences of different weather situations, dilution conditions and light-path locations were investigated as well. The results show that the differences between path-integrated and in situ mixing ratios were affected by combinations of emission source strengths, weather conditions, chemical transformations and local convection. Path-integrated measurements satisfy the requirements of traffic emission investigations better than in situ measurements.
Keywords: DOAS; Traffic-related emissions; Meteorological parameters; Air quality; Urban environment;

Acidifier application rate impacts on ammonia emissions from US roaster chicken houses by Sanjay B. Shah; Jesse L. Grimes; Edgar O. Oviedo-Rondón; Philip W. Westerman (576-583).
Due to its potential environmental and public health impacts, emissions of ammonia (NH3) as well as several other gases from US livestock farms may be regulated. Broiler houses are important sources of NH3 emissions. However, there are no emissions data from roaster (8–12 wk old broilers, ∼4 kg ea.) houses. Producers treat the litter in broiler houses with acidifiers, such as sodium bisulfate (SBS, NaHSO4) to reduce ammonia production and protect bird health. However, there is very little data on the effect of acidifiers, particularly at high application rates on ammonia emissions. The impact of different SBS application rates [High (0.95–1.46 kg m−2, whole house), Medium (0.73 kg m−2, whole house), Low (0.37–0.49 kg m−2, whole house), and Control (0.37–0.49 kg m−2, brood chamber)] on ammonia emissions was evaluated in commercial roaster houses over 22 months spanning eight flocks. Ammonia emission from each fan was measured with an acid scrubber that operated only when the fan operated. Emissions were calculated using >95% measured data with the rest being estimated using robust methods. Exhaust ammonia–N concentrations were inversely correlated with the SBS application rates. Emission rates on animal unit (AU, where 1 AU = 500 kg live-mass) basis (ER, g d−1 AU−1) were reduced by 27, 13, and 5%, respectively, in the High, Medium, and Low treatments vs. the Control treatment (mean: 100 g d−1 AU−1, range: 86–114 g d−1 AU−1). Emission rates for the Control treatment measured in this study on roasters were mostly higher than ERs in the literature. Differences in ERs are not only due to diet, environmental and management conditions, but also due to measurement methods.► Ammonia emission rates from four roaster houses were measured over eight flocks. ► Each house received a different acidifier (sodium bisulfate) application rate. ► The control treatment daily ammonia–N emission rate was 100 g per 500-kg live-mass. ► Emission rates were inversely correlated with the acidifier application rate. ► The acidifier is limited in its ability to reduce ammonia emissions.
Keywords: Broiler; Litter amendment; Acid trap; Impingers; Bubblers; Emission rate; Ventilation;

Improving ammonia emissions in air quality modelling for France by Lynda Hamaoui-Laguel; Frédérik Meleux; Matthias Beekmann; Bertrand Bessagnet; Sophie Génermont; Pierre Cellier; Laurent Létinois (584-595).
We have implemented a new module to improve the representation of ammonia emissions from agricultural activities in France with the objective to evaluate the impact of such emissions on the formation of particulate matter modelled with the air quality model CHIMERE. A novel method has been set up for the part of ammonia emissions originating from mineral fertilizer spreading. They are calculated using the one dimensional 1D mechanistic model “VOLT'AIR” which has been coupled with data on agricultural practices, meteorology and soil properties obtained at high spatial resolution (cantonal level). These emissions display high spatiotemporal variations depending on soil pH, rates and dates of fertilization and meteorological variables, especially soil temperature. The emissions from other agricultural sources (animal housing, manure storage and organic manure spreading) are calculated using the national spatialised inventory (INS) recently developed in France. The comparison of the total ammonia emissions estimated with the new approach VOLT'AIR_INS with the standard emissions provided by EMEP (European Monitoring and Evaluation Programme) used currently in the CHIMERE model shows significant differences in the spatiotemporal distributions. The implementation of new ammonia emissions in the CHIMERE model has a limited impact on ammonium nitrate aerosol concentrations which only increase at most by 10% on the average for the considered spring period but this impact can be more significant for specific pollution episodes. The comparison of modelled PM10 (particulate matter with aerodynamic diameter smaller than 10 μm) and ammonium nitrate aerosol with observations shows that the use of the new ammonia emission method slightly improves the spatiotemporal correlation in certain regions and reduces the negative bias on average by 1 μg m−3. The formation of ammonium nitrate aerosol depends not only on ammonia concentrations but also on nitric acid availability, which is often a limiting factor in rural regions in France, and on meteorological conditions. The presented approach of ammonia emission calculation seems suitable for use in chemistry–transport models.► NH3 emissions from mineral fertilizer spreading in France are simulated using a 1D mechanistic model. ► Emissions display high spatiotemporal variations depending especially on soil pH and rates and dates of fertilization. ► The comparison of modelled PM10 with observations shows that the spatiotemporal correlation is slightly improved.
Keywords: Modelling; Agriculture; Ammonia; Emissions; Air quality; PM10; Ammonium nitrate;