Atmospheric Environment (v.86, #C)

The development of seasonal emission factors from a Canadian commercial laying hen facility by Robert J. Morgan; David J. Wood; Bill J. Van Heyst (1-8).
Pollutants emitted from poultry housing facilities are a concern from a human health, bird welfare, and environmental perspective. Development of emission factors for these aerial pollutants is difficult due to variable climatic conditions, the number and type of poultry, and the wide range of management practices used. To address these concerns, a study was conducted to develop emission factors for ammonia and particulate matter over a period of one year from a commercial poultry laying hen facility in Wellington County, Ontario, Canada.Instruments housed inside an on-site mobile trailer were used to monitor in-house concentrations of ammonia and size fractionated particulate matter via a heated sample line. Along with a ventilation profile, emission factors were developed for the facility. Average emissions of 19.53 ± 19.97, 2.55 ± 2.10, and 1.10 ± 1.52 g day−1 AU−1 (where AU is defined as an animal unit equivalent to 500 kg live mass) for ammonia, PM10, PM2.5, respectively, were observed. All emissions peaked during the winter months, with the exception of PM2.5 which increased in the summer.
Keywords: Ammonia; Particulate matter; Emission factors; Poultry; Laying hen; Odor;

Odor measurements according to EN 13725: A statistical analysis of variance components by Johannes V. Klarenbeek; Nico W.M. Ogink; Hilko van der Voet (9-15).
In Europe, dynamic olfactometry, as described by the European standard EN 13725, has become the preferred method for evaluating odor emissions emanating from industrial and agricultural sources. Key elements of this standard are the quality criteria for trueness and precision (repeatability). Both are linked to standard values of n-butanol in nitrogen. It is assumed in this standard that whenever a laboratory complies with the overall sensory quality criteria for n-butanol, the quality level is transferable to other, environmental, odors.Although olfactometry is well established, little has been done to investigate inter laboratory variance (reproducibility). Therefore, the objective of this study was to estimate the reproducibility of odor laboratories complying with EN 13725 as well as to investigate the transferability of n-butanol quality criteria to other odorants.Based upon the statistical analysis of 412 odor measurements on 33 sources, distributed in 10 proficiency tests, it was established that laboratory, panel and panel session are components of variance that significantly differ between n-butanol and other odorants (α = 0.05). This finding does not support the transferability of the quality criteria, as determined on n-butanol, to other odorants and as such is a cause for reconsideration of the present single reference odorant as laid down in EN 13725.In case of non-butanol odorants, repeatability standard deviation (s r ) and reproducibility standard deviation (s R ) were calculated to be 0.108 and 0.282 respectively (log base-10). The latter implies that the difference between two consecutive single measurements, performed on the same testing material by two or more laboratories under reproducibility conditions, will not be larger than a factor 6.3 in 95% of cases.As far as n-butanol odorants are concerned, it was found that the present repeatability standard deviation (s r  = 0.108) compares favorably to that of EN 13725 (s r  = 0.172). It is therefore suggested that the repeatability limit (r), as laid down in EN 13725, can be reduced from r ≤ 0.477 to r ≤ 0.31.
Keywords: CEN standard EN 13725:2003; Odor measurement; Repeatability; Reproducibility; Uncertainty; Variance components;

Concentration and source identification of polycyclic aromatic hydrocarbons (PAHs) in PM10 of urban, industrial and semi-urban areas in Malaysia by Anas Ahmad Jamhari; Mazrura Sahani; Mohd Talib Latif; Kok Meng Chan; Hock Seng Tan; Md Firoz Khan; Norhayati Mohd Tahir (16-27).
Particulate matter (PM10) associated with polycyclic aromatic hydrocarbons (PAHs) in ambient air were determined at two sites within the Klang Valley, Kuala Lumpur (urban, KL) and Petaling Jaya (industrial, PJ), and one site outside the Klang Valley, Bangi (semi-urban, BG). This study aimed to determine the concentration and distribution of PAHs in PM10 and the source of origin through principal component analysis (PCA) and diagnostic ratio analysis. This study also assessed the health risk from exposure to airborne BaPeq. PM10 samples were collected on glass fiber filter paper using a High Volume Sampler (HVS) for 24 h between September 2010 and April 2011. The filter papers with PM10 were extracted using dichloromethane-methanol (3:1), and analysis of 16 USEPA priority PAHs was determined using gas chromatography with mass spectra (GC–MS). Health risk assessment was estimated using toxic equivalency factors (TEFs) and incremental lifetime cancer risk (ILCR) which quantitatively estimate the exposure risk for age specific group. The results showed that the total PAHs concentrations throughout seasonal monsoons for KL, PJ and BG ranged from 1.33 ng m−3 to 2.97 ng m−3, 2.24 ng m−3 to 4.84 ng m−3 and 1.64 ng m−3 to 3.45 ng m−3 respectively. More than 80% of total PAHs consisted of 5-ring and 6-ring PAHs such as benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (IcP), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF) and benzo[g,h,i]perylene (BgP). The presence of benzo[g,h,i]perylene (BgP) with high concentration at all locations suggested a source indicator for traffic emission. PCA and diagnostic ratio analysis also suggested substantial contributions from traffic emission with minimal influence from coal combustion and natural gas emissions. The use of total BaPeq concentration provide a better estimation of carcinogenicity activities, where they contributed to more than 50% of the potential health risk. Health risk assessment showed that the estimated incremental lifetime cancer risk (ILCR) from exposure to airborne BaPeq is negligible at all sampling sites for all age specific group.
Keywords: Particulate matter; PAHs; Traffic emission; Principal component analysis; Diagnostic ratio; Toxic equivalent factors; Health risk assessment;

We measured growth of the terrestrial moss Pseudoscleropodium purum during several well defined periods (monthly and quarterly between January 2008 and December 2009) at seven sampling sites affected by different climatic conditions. We also measured the concentrations of Cd, Cu, Hg, Pb and Zn in different moss segments comprising the tissue grown during each period. The concentrations of heavy metals in the different portions of moss shoots were highly variable, probably because of the high spatial and temporal variability in the growth rates of P. purum and the differences in the cation uptake/retention capacities of old and new tissues. The error associated with measurement of the concentrations of heavy metals in individual segments of the moss shoots ranged between 18 and 41%. The concentrations of Cd, Cu, Hg, Pb and Zn in the moss tissues appear to be more closely related to the physicochemical characteristics and the moss metabolism than to any preferential accumulation in young or old tissues. We conclude that comparison of the results of different biomonitoring studies is not valid, even when the same parts of the moss shoots are analyzed. Therefore, we recommend the use of green parts of moss shoots, as this would reduce the effect of tissue ageing on the cation uptake/retention capacity, although this prevents the establishment of a chronological relationship between the concentrations of heavy metals in moss tissues and atmospheric deposition.
Keywords: Pseudoscleropodium purum; Passive biomonitoring; Air quality; Moss growth; Heavy metals;

Effect of dead leaves on early spring dust emission in East Asia by Jung-Yoon Kang; Taichu Y. Tanaka; Masao Mikami (35-46).
Dead leaves remaining after the growing season can suppress dust emission by wind erosion, but this has not been considered in numerical models of dust emission. We investigated the effect of dead leaves by analyzing surface meteorological data and numerical simulations for early spring Asian dust events, and propose a parameterization of the dead-leaf effect. World Meteorological Organization (WMO) synoptic data indicate that high vegetation cover from the previous year can increase the threshold friction velocity for early spring of the following year. The reduction rate of dead leaves is calculated using 10-year averaged monthly vegetation cover data derived from the Normalized Difference Vegetation Index (NDVI), assuming that the amount of dead leaves decreases linearly, and the amount of dead leaves is included in calculating threshold friction velocity. To investigate the effect of dead leaves in simulations of Asian dust events, case studies were carried out with and without the dead-leaf effect for early spring Asian dust events using a Weather Research and Forecasting with Chemistry (WRF-Chem) model with a new dust emission scheme. Including the dead-leaf effect improved the model results, and the modeled surface concentrations are similar to the observed PM10 concentrations.
Keywords: Dead leaf; Dust emission; NDVI; WRF-Chem;

Mass of ambient particulate organic matter (OM) is often estimated by multiplying the organic carbon (OC) mass by a fixed factor that typically ranges from 1.4 to 1.8. In this paper, we develop a non-destructive, mid-infrared spectroscopic (MIR) technique to measure OM in PM2.5 collected on PTFE filters (commonly called “teflon” filters). MIR techniques measure absorption by functional groups within organic molecules; that is, carbon atoms bonded to oxygen (O) or hydrogen (H), O bonded to H and other elements bonded together in organic molecules that comprise OM. We developed laboratory standards of atmospherically relevant organic compounds as the basis for calibrating the MIR absorption to the moles of functional groups. A multivariate regression technique was used to develop calibrations for quantifying alkane CH, alcohol OH, carboxylic acid OH, and carbonyl, which likely comprise the bulk of OM in most ambient samples. OM is estimated as the sum of masses attributed to these functional groups. The precision of the OM measurement is 6.9 μg (relative precision is 7%) and the minimum detection limit is 4.8 μg, corresponding to an ambient concentrations of 0.21 μg m−3 and 0.15 μg m−3 respectively, for the sampling protocol used here.The method was employed to estimate OM, OC (estimated as the sum of the mass of carbon in the alkane CH and carbonyl functional groups) and OM/OC from one year of routinely collected filters at seven Interagency Monitoring of Protected Visual Environments (IMPROVE) sites. In the IMPROVE network, OC is measured using a thermal optical method and OM is estimated for regional haze tracking simply as 1.8 × OC. Using the MIR technique on one year of samples from 7 IMPROVE sites, the median OM/OC ratio was 1.69 with the 10th and 90th percentiles of 1.46 and 2.01. Phoenix, AZ had the lowest annual-median value of 1.56 and Mesa Verde, CO had the highest of 1.83. For more than half of the sites, the lowest monthly-median OM/OC ratio occurred in winter. The sample, site median and seasonal median OM/OC ratios obtained from MIR analysis indicate that a single estimate of OM/OC does not represent the observed variability in OM/OC.
Keywords: FTIR; Functional groups; Carboxylic acid; OM; OC; Organic matter;

The impact of meteorological parameters on urban air quality by Nicole R. Ramsey; Petra M. Klein; Berrien Moore (58-67).
Previous studies have shown that global climate change will have a significant impact on both regional and urban air quality. As air temperatures continue to rise and mid-latitude cyclone frequencies decrease, the overall air quality is expected to degrade. Climate models are currently predicting an increased frequency of record setting heat and drought for Oklahoma during the summer months. A statistical analysis was thus performed on ozone and meteorological data to evaluate the potential effect of increasing surface temperatures and stagnation patterns on urban air quality in the Oklahoma City Metropolitan area.Compared to the climatological normal, the years 2011 and 2012 were exceptionally warm and dry, and were therefore used as case study years for determining the impact of hot, dry conditions on air quality. These results were then compared to cooler, wetter summers to show how urban air quality is affected by a change in meteorological parameters. It was found that an increase in summertime heat and a decrease in summertime precipitation will lead to a substantial increase in both the minimum and maximum ozone concentrations as well as an increase in the total number of exceedance days. During the hotter, drier years, the number of days with ozone concentrations above the legal regulatory limit increased nearly threefold. The length of time in which humans and crops are exposed to these unsafe levels was also doubled. Furthermore, a significant increase was noted in the overnight minimum ozone concentrations. This in turn can lead to significant, adverse affects on both health and agriculture statewide.
Keywords: Ozone concentrations; Climate change; Urban air quality; Health impacts; Oklahoma City;

Low-molecular-weight organic acids in the Tibetan Plateau: Results from one-year of precipitation samples at the SET station by Bin Liu; Shichang Kang; Jimin Sun; Xin Wan; Yongjie Wang; Shaopeng Gao; Zhiyuan Cong (68-73).
Background atmospheric organic acids: formic (F), acetic (A), oxalic (O), and methanesulfonic (MSA, abbreviated to M) acids in the southern Tibetan Plateau (TP), were determined in one-year of precipitation measurements at a remote alpine station. These organic acids were dominated by oxalic (volume-weighted mean of 0.51 μmol l 1)/formic acid (0.38 μmol l 1), followed by acetic acid (0.20 μmol l 1) and MSA (0.10 μmol l 1). Their levels were comparable with those from other remote sites, while they were lower than those found in populated areas. The South Asian monsoon is responsible for the seasonal variation of organic acid concentration: a relative abundance of MSA and lower concentrations of other organic acids (by the dilution effect) in the monsoon season, while opposite in the non-monsoon season. Diverse sources were identified by principal component analysis combined with the corresponding tracers. These were anthropogenic disturbances (which explain 41% of the variance), marine emission (24%), and biogenic emission (16%). Moreover, the variances of F/A, M/(F + A), and O/(F + A) in monsoonal versus non-monsoonal samples, were involved with the changes of sources. Furthermore, these chemical indexes suggest that active photochemistry over the TP was significant for the production of organic acids and consequently enhanced the ratios of M/(F + A) and O/(F + A) in monsoonal rainfalls. The elevated organic compounds within the ascending tropical moisture imply potential significances for the secondary formation of organic acids in the high-altitude and the changes of the Asian monsoon.
Keywords: Organic acids; Precipitation chemistry; Tibetan Plateau; Monsoon;

Mapping ozone risks for rice in China for years 2000 and 2020 with flux-based and exposure-based doses by Haoye Tang; Jing Pang; Gongxuan Zhang; Masayuki Takigawa; Gang Liu; Jianguo Zhu; Kazuhiko Kobayashi (74-83).
We parameterized a multiplicative model of stomatal conductance (g sto) for O3 uptake by rice leaves with the field measurements in a fully open-air ozone (O3) fumigation experiment. The estimated g sto compared well with the observed one (r 2 = 0.79). By using the g sto model for O3 uptake, we estimated a flux-based O3 risk (POD6, accumulated stomatal flux of O3 above a threshold of 6 nmol m−2 s−1) for rice across China in years 2000 and 2020, and compared it with the exposure-based O3 risk (AOT40, accumulated hourly O3 concentration above 40 ppb during daytime) for the same period. For the year 2000, both POD6 and AOT40 indicated the middle and lower reaches of Yangtze River and the south China being at the highest O3 risk. From the years 2000–2020, the O3 risks are projected to double (POD6) or triple (AOT40) in a majority of rice producing areas in the above two regions. Among three major rice cropping in the middle and lower reaches of Yangtze River, double-late rice is projected to have lower O3 risk than double-early rice and single rice on the either O3 risk measure in both 2000 and 2020. In south China, on the other hand, the O3 risks for double-late rice are comparable to that for early double-rice. In this study, the O3 risk was not measured as yield loss but as O3 flux and O3 exposure. The crop loss estimation would require a relationship between O3 flux and yield loss for major rice production regions across China.
Keywords: AOT40; Ozone flux; Stomatal conductance model; Risk assessment; Rice; China;

Determinants of the spatial distributions of elemental carbon and particulate matter in eight Southern Californian communities by Robert Urman; James Gauderman; Scott Fruin; Fred Lurmann; Feifei Liu; Reza Hosseini; Meredith Franklin; Edward Avol; Bryan Penfold; Frank Gilliland; Bert Brunekreef; Rob McConnell (84-92).
Emerging evidence indicates that near-roadway pollution (NRP) in ambient air has adverse health effects. However, specific components of the NRP mixture responsible for these effects have not been established. A major limitation for health studies is the lack of exposure models that estimate NRP components observed in epidemiological studies over fine spatial scale of tens to hundreds of meters. In this study, exposure models were developed for fine-scale variation in biologically relevant elemental carbon (EC). Measurements of particulate matter (PM) and EC less than 2.5 μm in aerodynamic diameter (EC2.5) and of PM and EC of nanoscale size less than 0.2 μm were made at up to 29 locations in each of eight Southern California Children's Health Study communities. Regression-based prediction models were developed using a guided forward selection process to identify traffic variables and other pollutant sources, community physical characteristics and land use as predictors of PM and EC variation in each community. A combined eight-community model including only CALINE4 near-roadway dispersion-estimated vehicular emissions accounting for distance, distance-weighted traffic volume, and meteorology, explained 51% of the EC0.2 variability. Community-specific models identified additional predictors in some communities; however, in most communities the correlation between predicted concentrations from the eight-community model and observed concentrations stratified by community was similar to those for the community-specific models. EC2.5 could be predicted as well as EC0.2. EC2.5 estimated from CALINE4 and population density explained 53% of the within-community variation. Exposure prediction was further improved after accounting for between-community heterogeneity of CALINE4 effects associated with average distance to Pacific Ocean shoreline (to 61% for EC0.2) and for regional NOx pollution (to 57% for EC2.5). PM fine spatial scale variation was poorly predicted in both size fractions. In conclusion, models of exposure that include traffic measures such as CALINE4 can provide useful estimates for EC0.2 and EC2.5 on a spatial scale appropriate for health studies of NRP in selected Southern California communities.
Keywords: Air pollution; Elemental carbon; Particulate matter; Exposure modeling;

An elaborate high resolution emission inventory of primary air pollutants for the Central Plain Urban Agglomeration of China by Peipei Qiu; Hezhong Tian; Chuanyong Zhu; Kaiyun Liu; Jiajia Gao; Junrui Zhou (93-101).
A high resolution emission inventory of primary air pollutants was developed based on the detailed collected activity data and the latest source-specific emission factors for the year 2010 in the Central Plain Urban Agglomeration (CPUA) region of China. The total emissions of SO2, NO x , PM10, PM2.5, CO, VOCs, and NH3 were estimated to be about 863.7 kt, 1058.2 kt, 1180.4 kt, 753.2 kt, 2854.3 kt, 466.1 kt, and 496.0 kt, respectively. Therein, power plants were demonstrated to be the largest sources for NO x , contributing about 36.1% of total emissions; industrial processes and biomass burning sources were proved to be the two major contributors of PM10, PM2.5 and VOCs emissions, together accounting for about 71.1%, 79.2% and 56.9% of the total emissions respectively. Besides, 18.4% of VOCs emissions can be explained by VOCs product-related sources. Other stationary combustion sources accounted for 57.7% of SO2 and 30.3% of CO emissions, respectively. Livestock and N-fertilizer application sources contributed about 81.0% of NH3 emissions together. Further, the emissions were spatially distributed into grid cells with a resolution of 3 km × 3 km, by using spatial allocation surrogates such as high resolution gridded population density and regional GDP. This inventory will benefit for policymakers and researchers to better understand the current situation of complex air pollution in the CPUA region of China and supply important necessary input for regional air quality modeling and policymaking.
Keywords: Emission inventory; Primary air pollutants; Spatial distribution; Temporal variation; The Central Plain Urban Agglomeration (CPUA) of China;

Historical industrial emissions of non-methane volatile organic compounds in China for the period of 1980–2010 by Kaiqiong Qiu; Lixian Yang; Junmin Lin; Peitao Wang; Yi Yang; Daiqi Ye; Liming Wang (102-112).
This paper presents a new classification of industrial sector on basis of a source-tracing method for the historical industrial emissions of non-methane volatile organic compounds (NMVOCs). The industrial sources were divided into four major source categories: production of NMVOCs, storage and transport, industrial processes using NMVOCs as raw materials, and processes using NMVOCs-containing products. Multiyear emission inventories of NMVOCs from industrial sources were established for the period of 1980–2010 in China, covering 98 contributing industrial sources. The inventories were developed by the emission factor method, and further gridded at a spatial resolution of 50 km × 50 km based on GIS methodology, using population data as spatial surrogate. The result showed that China's industrial NMVOCs emissions had increased by 11.6 times at an average annual rate of 8.5% from 1.15 Tg in 1980 to 13.35 Tg in 2010. The four major source categories generated 19.6% (2.63 Tg, production of NMVOCs), 9.6% (1.295 Tg, storage and transport), 13.2% (1.769 Tg, industrial processes using NMVOCs as raw materials), and 57.4% (7.662 Tg, processes using NMVOCs-containing products) of the total emissions from China in 2010. Moreover, the top four industrial emissions sources were oil refinery, architectural decoration, machinery equipment and printing, accounted for 48.3% all together. With respect to the spatial distribution, the emissions mostly occurred in the eastern, northern and southern parts of China, all being much higher than that in the western part. The top four emission provinces were Shandong, Jiangsu, Guangdong, and Zhejiang, accounting for 38.3% of the national emissions. As for the past 30 years, the national industrial NMVOCs emissions increased year-by-year, being in pace with the accelerated industrialization process and the sharp economic growth, especially the rapid expansion of the high-emission industries. Particularly, the oil refinery, product oil and solvent distribution, architectural decoration, and mechanical equipment manufacture became the four largest contributors, accounting for 15.9–34.3%, 6.5–10.2%, 7–8%, and 6–7% of national industrial NMVOCs.
Keywords: NMVOCs; Emission inventory; Industrial emissions; China;

Implementation of a low emission zone and evaluation of effects on air quality by long-term monitoring by Pavlos Panteliadis; Maciej Strak; Gerard Hoek; Ernie Weijers; Saskia van der Zee; Marieke Dijkema (113-119).
A regulation was implemented on 9/1/2009, excluding Euro 0, I and II heavy duty vehicles from entering Amsterdam's Low Emission Zone (LEZA). The current study investigated whether and to what extent this regulation had an effect on air quality. Data for a period starting two years before the regulation up to 31 December 2010 were obtained from two monitoring sites within the LEZA, one located in a street frequently used by heavy-duty vehicles, and one at an urban background location. The difference in concentrations of NO2, NOx, PM10 and soot, between the two sites was attributed to traffic. Soot was measured by two proxies, Elemental Carbon (EC) and Absorbance that showed a significant mutual correlation. The traffic contribution concentrations measured were adjusted for wind direction, wind speed, type of day (weekday/weekend) and traffic intensity. Since the implementation of the LEZA, the traffic contribution concentrations compared to the roadside site concentrations were decreased by 4.9% (95%-CI: 3.0–6.9%) for NO2, 5.9% (95%-CI: 3.7–6.4%) for NOx, 5.8% (95%-CI: 3.3–8.4%) for PM10, 7.7% (95%-CI: 2.3–13.0%) for Absorbance and 12.9% (95%-CI: 5.2–20.5%) for EC. The current study demonstrated significant decreases in traffic-related air pollution concentrations in the vicinity of a roadside monitoring station after the implementation of a low emission zone in Amsterdam.
Keywords: Air pollution; Low emission zone; Traffic emissions; Soot; EC; Absorbance; PM10; NO2; NOx;

The diurnal variation of NOx and O3 exchange between a street canyon and the overlying air in two dimensions is investigated to understand reactive pollutant removal and entrainment across the roof level of the street canyon. The computational fluid dynamics (CFD) model used in this study is a Reynolds-averaged Navier–Stokes equations (RANS) model and includes the urban surface and radiation processes and the comprehensive chemical processes. The CFD model is used for the one-day simulation in which the easterly ambient wind blows perpendicular to the north–south oriented street canyon with a canyon aspect ratio of 1. In the morning when the surface temperature of the downwind building wall is higher than that of the upwind building wall, two counter-rotating vortices appear in the street canyon (flow regime II). In the afternoon when the surface temperature of the upwind building wall is higher than that of the downwind building wall, an intensified primary vortex appears in the street canyon (flow regime I). The NOx and O3 exchange is generally active in the region close to the building wall with the higher temperature regardless of flow regime. The NOx and O3 exchange by turbulent flow is dominant in flow regime II, whereas the NOx and O3 exchange by mean flow becomes comparable to that by turbulent flow in a certain period of flow regime I. The NOx and O3 exchange velocities are similar to each other in the early morning, whereas these are significantly different from each other around noon and in the afternoon. This behavior indicates that the exchange velocity is dependent on flow regime. In addition, the diurnal variability of O3 exchange velocity is found to be dependent on photochemistry rather than dry deposition in the street canyon. This study suggests that photochemistry as well as flow in a street canyon is needed to be taken into account when exchange velocities for reactive pollutants are estimated.
Keywords: Street canyon; NOx removal; O3 entrainment; Diurnal variation; Surface heating; CFD model;

Fine particle emissions in three different combustion conditions of a wood chip-fired appliance – Particulate physico-chemical properties and induced cell death by J. Leskinen; J. Tissari; O. Uski; A. Virén; T. Torvela; T. Kaivosoja; H. Lamberg; I. Nuutinen; T. Kettunen; J. Joutsensaari; P.I. Jalava; O. Sippula; M.-R. Hirvonen; J. Jokiniemi (129-139).
A biomass combustion reactor with a moving grate was utilised as a model system to produce three different combustion conditions corresponding to efficient, intermediate, and smouldering combustion. The efficient conditions (based on a CO level of approximately 7 mg MJ−1) corresponded to a modern pellet boiler. The intermediate conditions (CO level of approximately 300 mg MJ−1) corresponded to non-optimal settings in a continuously fired biomass combustion appliance. The smouldering conditions (CO level of approximately 2200 mg MJ−1) approached a batch combustion situation. The gaseous and particle emissions were characterised under each condition. Moreover, the ability of fine particles to cause cell death was determined using the particle emissions samples.The physico-chemical properties of the emitted particles and their toxicity were considerably different between the studied combustion conditions. In the efficient combustion, the emitted particles were small in size and large in number. The PM1 emission was low, and it was composed of ash species. In the intermediate and smouldering combustion, the PM1 emission was higher, and the particles were larger in size and smaller in number. In both of these conditions, there were high-emission peaks that produced a significant fraction of the emissions. The PAH emissions were the lowest in the efficient combustion. The smouldering combustion conditions produced the largest PAH emissions.In efficient combustion conditions, the emitted fine particles had the highest potential to cause cell death. This finding was most likely observed because these fine particles were mainly composed of inorganic ash species, and their relative contents of Zn were high. Thus, even the PM1 from optimal biomass combustion might cause health effects, but in these conditions, the particle emissions per energy unit produced were considerably lower.
Keywords: Biomass combustion; Particle characterisation; Toxicological response;

Comparison of three nanoparticle sizing instruments: The influence of particle morphology by Naomi Zimmerman; Krystal J. Godri Pollitt; Cheol-Heon Jeong; Jonathan M. Wang; Terry Jung; Josephine M. Cooper; James S. Wallace; Greg J. Evans (140-147).
The TSI Fast Mobility Particle Sizer (FMPS), Engine Exhaust Particle Sizer (EEPS), and Scanning Mobility Particle Sizer (SMPS) provide size distributions for 6–560 nm particles. The aim of this study was to perform comprehensive equivalence testing of these three particle sizing instruments with particles of contrasting chemical and physical characteristics (urban ambient, diesel exhaust, and laboratory-generated particulate). It was observed that the EEPS and FMPS measurements agreed to within 15% thus concluding that data from these instruments may be considered equivalent. Parallel measurements with the SMPS showed that when measuring diesel exhaust particulate during ISO8178 Mode 9 operation there is significant overestimation of particle concentrations by both the EEPS and the FMPS in the 20–120 nm size range (25–38% overestimation). This overestimation also occurred for near-road measurement of heavy emitter vehicle plumes in ambient samples (up to 75% overestimation). Laboratory-generated soot agglomerate particles, whose shape was verified by transmission electron microscopy, were also tested. The agglomerate nature of diesel soot particulate was the dominant cause of the overestimation; parallel measurements with an FMPS and an Ultrafine Condensation Particle Counter of the laboratory-generated soot particulate showed overestimation by up to a factor of three.
Keywords: EEPS; FMPS; SMPS; Equivalency; Diesel; Morphology;

Carbon isotopic characterization of formaldehyde emitted by vehicles in Guangzhou, China by Ping Hu; Sheng Wen; Yonglin Liu; Xinhui Bi; Lo Yin Chan; Jialiang Feng; Xinming Wang; Guoying Sheng; Jiamo Fu (148-154).
Formaldehyde (HCHO) is the most abundant carbonyl compound in the atmosphere, and vehicle exhaust emission is one of its important anthropogenic sources. However, there is still uncertainty regarding HCHO flux from vehicle emission as well as from other sources. Herein, automobile source was characterized using HCHO carbon isotopic ratio to assess its contributions to atmospheric flux and demonstrate the complex production/consumption processes during combustion in engine cylinder and subsequent catalytic treatment of exhaust. Vehicle exhausts were sampled under different idling states and HCHO carbon isotopic ratios were measured by gas chromatograph–combustion–isotopic ratio mass spectrometry (GC–C–IRMS). The HCHO directly emitted from stand-alone engines (gasoline and diesel) running at different load was also sampled and measured. The HCHO carbon isotopic ratios were from −30.8 to −25.7‰ for gasoline engine, and from −26.2 to −20.7‰ for diesel engine, respectively. For diesel vehicle without catalytic converter, the HCHO carbon isotopic ratios were −22.1 ± 2.1‰, and for gasoline vehicle with catalytic converter, the ratios were −21.4 ± 0.7‰. Most of the HCHO carbon isotopic ratios were heavier than the fuel isotopic ratios (from −29 to −27‰). For gasoline vehicle, the isotopic fractionation (Δ13C) between HCHO and fuel isotopic ratios was 7.4 ± 0.7‰, which was higher than that of HCHO from stand-alone gasoline engine (Δ13Cmax = 2.7‰), suggesting additional consumption by the catalytic converter. For diesel vehicle without catalytic converter, Δ13C was 5.7 ± 2.0‰, similar to that of stand-alone diesel engine. In general, the carbon isotopic signatures of HCHO emitted from automobiles were not sensitive to idling states or to other vehicle parameters in our study condition. On comparing these HCHO carbon isotopic data with those of past studies, the atmospheric HCHO in a bus station in Guangzhou might mainly come from vehicle emission for the accordance of carbon isotopic data.
Keywords: Formaldehyde; Vehicle emission; Carbon isotope; Emission factor;

Methoxyphenols are low molecular weight semi-volatile polar aromatic compounds produced from the pyrolysis of wood lignin. The reaction of guaiacol (2-methoxyphenol) with hydroxyl radicals has been studied in the LPCA simulation chamber at (294 ± 2) K, atmospheric pressure, low relative humidity (RH < 1%) and under high-NO x conditions using CH3ONO as OH source. The aerosol production was monitored using a SMPS (Scanning Mobility Particle Sizer); the SOA yields were in the range from 0.003 to 0.87 and the organic aerosol formation can be expressed by a one-product gas/particle partitioning absorption model. Transmission (TEM) and Scanning (SEM) Electron Microscopy observations were performed to characterize the physical state of SOA produced from the OH reaction with guaiacol; they display both liquid and solid particles (in an amorphous state).GC-FID (Gas Chromatography – Flame Ionization Detection) and GC-MS (Gas Chromatography – Mass Spectrometry) analysis show the formation of nitroguaiacol isomers as main oxidation products in the gas- and aerosol-phases. In the gas-phase, the formation yields were (10 ± 2) % for 4-nitroguaiacol (1-hydroxy-2-methoxy-4-nitrobenzene; 4-NG) and (6 ± 2) % for 3- or 6-nitroguaiacol (1-hydroxy-2-methoxy-3-nitrobenzene or 1-hydroxy-2-methoxy-6-nitrobenzene; 3/6-NG; the standards are not commercially available so both isomers cannot be distinguished) whereas in SOA their yield were much lower (≤0.1%).To our knowledge, this work represents the first identification of nitroguaiacols as gaseous oxidation products of the OH reaction with guaiacol. As the reactivity of nitroguaiacols with atmospheric oxidants is probably low, we suggest using them as biomass burning emission gas tracers. The atmospheric implications of the guaiacol + OH reaction are also discussed.
Keywords: Simulation chamber; OH reaction; Guaiacol; Nitroguaiacols; Secondary organic aerosol;

In the framework of the “Supersito” project, three intensive experimental campaigns were conducted in the Po Valley (Northern Italy) in cold seasons, such as late autumn, pre-winter and deep-winter, over three years from 2011 to 2013. As a part of a study on polar marker compounds, including carboxylic acids, sugar derivatives and lignin phenols, the present study reports a detailed discussion on the atmospheric concentrations of 14 low molecular weight carboxylic acids, mainly dicarboxylic and oxo-hydroxy carboxylic acids, as relevant markers of primary and secondary organic aerosols.PM2.5 samples were collected in two monitoring sites, representing urban and rural background stations. The total quantities of carboxylic acids were 262, 167 and 249 ng m−3 at the urban site and 308, 115, 248 ng m−3 at the rural site in pre-winter, fall and deep-winter, respectively. These high concentrations can be explained by the large human emission sources in the urbanized region, combined with the stagnant atmospheric conditions during the cold seasons that accumulate the organic precursors and accelerate the secondary atmospheric reactions.The distribution profiles of the investigated markers suggest the dominant contributions of primary anthropogenic sources, such as traffic, domestic heating and biomass burning. These results are confirmed by comparison with additional emission tracers, such as anhydro-saccharides for biomass burning and fatty acids originated from different anthropogenic sources. In addition, some secondary constituents were detected in both sites, as produced by in situ photo-chemical reactions from both biogenic (e.g. pinonic acid) and anthropogenic precursors (e.g. phthalic and adipic acids).The impact of different sources from human activities was elucidated by investigating the week pattern of carboxylic and fatty acid concentrations. The weekly trends of analytes during the warmer campaign (fall 2012; mean temperature: 12 °C) may be related to emissions from motor vehicle traffic and industrial activities. Otherwise, the random pattern of the markers suggests the prevalent contribution of primary emissions from residential heating in the colder deep-winter (mean temperature: 5 °C).
Keywords: Low molecular weight carboxylic acids; Atmospheric aerosol; Anthropogenic and biogenic emission sources; Po Valley; Cold seasons;

A direct method of measuring gaseous emissions from naturally ventilated dairy barns by H.S. Joo; P.M. Ndegwa; A.J. Heber; B.W. Bogan; J.-Q. Ni; E.L. Cortus; J.C. Ramirez-Dorronsoro (176-186).
Air pollutant emission rates from mechanically ventilated (MV) dairy barns are determined from the product of the differences in concentrations of pollutants in air at the inlet and exhaust points and the corresponding ventilation rates. In contrast to well defined entry and exit points in MV barns, large area air inlets or outlets characterize naturally ventilated (NV) freestall dairy barns. Complicating this scenario even more, pertinent airflow characteristics (velocity and direction) necessary for determining ventilation rates vary continuously, both temporally and spatially. This paper describes implementation of a direct method, generally equivalent to the approach used for MV barns, for determining air emission rates of NV barns. Ultrasonic anemometers (sonics) located at salient points in the barn openings mapped air inflow and outflow velocities necessary to calculate ventilation rates. Pollutant concentrations in the air entering or leaving the barn during a given period were measured at sampling points located next to the anemometers. The air inflow rates were, in general, higher than the air outflow rates from the barns, but diurnal profiles were similar. The observed ventilation characteristics were consistent with prevailing wind directions. Air inflows were observed predominantly at windward openings of the barn, while the outflows were mainly at the barn's leeward openings. Results indicated that either: (i) the average of the air inflow and outflow rates (averaging approach), or (ii) the air inflow rates (inflow-only approach) were credible representations of ventilation rates. Results also revealed use of an on-site weather station and one sonic mounted in the middle of each wall of the barn as a possible approach for determining barn ventilation rates. The suggested use of ventilation rates for interpolating missing concentrations from intermittent gas measurements could potentially increase the integrity of emission rates at significantly lower capital investment and operational costs.
Keywords: Emission rates; Area inlets; Area outlets; Ultrasonic anemometer; Direct ventilation rates; Indirect ventilation rates;

Observations of residual submicron fine aerosol particles related to cloud and fog processing during a major pollution event in Beijing by Zhengqiang Li; Tom Eck; Ying Zhang; Yuhuan Zhang; Donghui Li; Li Li; Hua Xu; Weizhen Hou; Yang Lv; Philippe Goloub; Xingfa Gu (187-192).
Residual aerosols, the particles left behind after droplet evaporation, are important tracers for aerosols processed by cloud and/or fog. Based on ground-based CIMEL sun–sky radiometer measurements during an extreme winter pollution event in Beijing, we present observations of the decrease of residual aerosol with dissipation of cloud and an unusual case of residual aerosol increase after partial dissipation of fog. This unusual increase might be an important mechanism for the haze growth in polluted regions. The aerosol single scattering albedo is found to increase with the increase of residual aerosol. We also find that residual aerosol dominated cases with significant water content gain can occur in a short time (e.g. one hour) with the increase of aerosol volume size and decrease of particle number. A lognormal residual aerosol size distribution model is proposed based on sun–sky radiometer measurements with center peak radius at 0.44 micron and geometric standard deviation of about 1.49.Display Omitted
Keywords: Residual size; Submicron fine mode aerosol; Size distribution; Cloud; Fog; Haze;

Fine particles (PM2.5) at a CAWNET background site in Central China: Chemical compositions, seasonal variations and regional pollution events by Fan Zhang; Hai-rong Cheng; Zu-wu Wang; Xiao-pu Lv; Zhong-min Zhu; Gan Zhang; Xin-ming Wang (193-202).
Fine particle (PM2.5) samples were collected at Jinsha (JSH), a regional background China Atmosphere Watch Network (CAWNET) site in Central China from March 2012 to March 2013. The mass concentrations of water-soluble inorganic ions (WSIIs), organic carbon (OC) and elemental carbon (EC) in PM2.5 were measured. The average PM2.5 mass concentration was 48.7 ± 26.9 μg m−3, exceeding the Chinese National Ambient Air Quality Standards (NAAQS) (35 μg m−3), implying that PM2.5 is a pollutant of regional concern in Central China. The average concentrations of total WSIIs, OC and EC were 26.1 ± 18.8, 7.5 ± 3.5 and 0.7 ± 0.5 μg m−3, accounting for 53.5%, 15.1% and 1.5% of the PM2.5 concentrations at JSH, respectively. Clear seasonal variations in PM2.5 and the levels of its main chemical species were observed in the following order: winter > autumn > spring > summer. Backward air trajectory analysis and potential source contribution function (PSCF) analysis implied that the areas north and northeast of JSH contributed significantly to the levels of SO4 2−, NO3 , NH4 + and OC, while sandstorms originating from Mongolia and traveling across Northwest China may have contributed significantly to the levels of Na+, Ca2+, and Mg2+ in PM2.5 at JSH. Two pollution events, related to regional biomass burning and haze, respectively, were recorded at JSH during the sampling campaign.
Keywords: PM2.5; Background; Long-range atmospheric transport; Back trajectory; Potential source contribution function (PSCF); Pollution events;

Temporal associations of ambient PM2.5 elemental concentrations with indoor and personal concentrations by Denise Montagne; Gerard Hoek; Mark Nieuwenhuijsen; Timo Lanki; Taina Siponen; Meritxell Portella; Kees Meliefste; Bert Brunekreef (203-211).
Time series studies increasingly evaluate health relevance of the elemental composition of particles smaller than 2.5 μm (PM2.5). Validation studies have documented that temporal variation of outdoor PM2.5 concentration is correlated with temporal variation of personal exposure, but very few papers have investigated the temporal correlation between outdoor concentration and personal exposure for the elemental composition of PM2.5. We evaluated the temporal association between outdoor concentration and personal exposure for the elements copper (Cu), zinc (Zn), iron (Fe), potassium (K), nickel (Ni), vanadium (V), silicon (Si) and sulfur (S) in three European cities.In Helsinki (Finland), Utrecht (the Netherlands) and Barcelona (Spain) five participants from urban background, five from suburban/rural background and five from busy street sites were selected (15 participants per city). Six outdoor, indoor and personal 96-h average PM2.5 concentrations were measured simultaneously in three different seasons (winter, summer and spring/autumn). Concurrently, samples were collected at a central reference site, reflecting urban background air pollution levels. The temporal variation at the central site was highly correlated with personal exposure for all elements, except Cu. The highest correlations (Pearson's R) were found for S and V (R between 0.87 and 0.98). Lower correlations were found for the elements Cu, Fe and Si associated with non-tailpipe traffic emissions and road dust (Pearson's R between −0.34 and 0.79). For PM2.5 mass the R was lower (between 0.37 and 0.70). Exclusion of observations most affected by indoor sources increased the personal to central site correlations but did not fully explain differences between elements. The generally high correlation between temporal variation of the outdoor concentration and personal exposure supports the use of a central site for assessing exposure of PM components in time series studies for most elements. The different correlations found for the eight elements suggests that epidemiological associations are affected by differences in measurement error.
Keywords: Particulate matter; Elemental composition; Temporal; Personal exposure;

Detailed diesel exhaust characteristics including particle surface area and lung deposited dose for better understanding of health effects in human chamber exposure studies by Aneta Wierzbicka; Patrik T. Nilsson; Jenny Rissler; Gerd Sallsten; Yiyi Xu; Joakim H. Pagels; Maria Albin; Kai Österberg; Bo Strandberg; Axel Eriksson; Mats Bohgard; Kerstin Bergemalm-Rynell; Anders Gudmundsson (212-219).
Several diesel exhaust (DE) characteristics, comprising both particle and gas phase, recognized as important when linking with health effects, are not reported in human chamber exposure studies. In order to understand effects of DE on humans there is a need for better characterization of DE when performing exposure studies. The aim of this study was to determine and quantify detailed DE characteristics during human chamber exposure. Additionally to compare to reported DE properties in conducted human exposures. A wide battery of particle and gas phase measurement techniques have been used to provide detailed DE characteristics including the DE particles (DEP) surface area, fraction and dose deposited in the lungs, chemical composition of both particle and gas phase such as NO, NO2, CO, CO2, volatile organic compounds (including aldehydes, benzene, toluene) and polycyclic aromatic hydrocarbons (PAHs). Eyes, nose and throat irritation effects were determined. Exposure conditions with PM1 (<1 μm) mass concentration 280 μg m−3, number concentration 4 × 105 cm−3 and elemental to total carbon fraction of 82% were generated from a diesel vehicle at idling. When estimating the lung deposited dose it was found that using the size dependent effective density (in contrast to assuming unity density) reduced the estimated respiratory dose by 132% by mass. Accounting for agglomerated structure of DEP prevented underestimation of lung deposited dose by surface area by 37% in comparison to assuming spherical particles. Comparison of DE characteristics reported in conducted chamber exposures showed that DE properties vary to a great extent under the same DEP mass concentration and engine load. This highlights the need for detailed and standardized approach for measuring and reporting of DE properties. Eyes irritation effects, most probably caused by aldehydes in the gas phase, as well as nose irritation were observed at exposure levels below current occupational exposure limit values given for exhaust fumes. Reporting detailed DE characteristics that include DEP properties (such as mass and number concentration, size resolved information, surface area, chemical composition, lung deposited dose by number, mass and surface) and detailed gas phase including components known for their carcinogenic and irritation effect (e.g. aldehydes, benzene, PAHs) can help in determination of key parameters responsible for observed health effects and comparison of chamber exposure studies.
Keywords: Diesel exhaust characteristics; Human laboratory exposure; Particle surface area; Lung deposited dose;

To better understand the methylation and demethylation of mercury (Hg) in the atmosphere, monomethyl mercury (MMHg) concentrations in wet deposition samples collected in the Minamata Bay area from September, 2009 to August, 2010 were determined. The concentrations of total Hg (dissolved Hg + particulate Hg) and dissolved reactive Hg were also measured. The volume-weighted mean concentrations of dissolved MMHg and total Hg were 0.061 and 5.9 ng L−1, respectively. Almost 90% of total Hg was in the dissolved phase and dissolved reactive Hg was the dominant Hg species in the wet deposition. The wet deposition fluxes of total Hg and reactive Hg increased in the rainy season (summer and fall), while the concentrations and wet deposition fluxes of MMHg were higher in winter and spring than in summer. Factors affecting this seasonal variation of MMHg were also considered. The MMHg in wet depositions may be decomposed by the increased levels of UV radiation in summer months, although MMHg can also be emitted from anthropogenic and biogenic sources and/or produced by photochemical reactions. Long-range transport from the Asian continent may also contribute to the seasonal variation of the wet MMHg deposition flux.
Keywords: Monomethylmercury; Reactive mercury; Dissolved mercury; Wet deposition; East Asia;

In-situ measurements of atmospheric aerosols by using Integrating Nephelometer over a semi-arid station, southern India by K. Rama Gopal; S.Md. Arafath; A.P. Lingaswamy; G. Balakrishnaiah; S. Pavan Kumari; K. Uma Devi; N. Siva Kumar Reddy; K. Raja Obul Reddy; M. Penchal Reddy; R.R. Reddy; S. Suresh Babu (228-240).
Continuous real-time measurements of aerosol scattering properties were investigated at Anantapur (14° 62 N, 77° 65 E, 331 m asl), a semi-arid region in southern India for the period of January 2011–December 2011, using a three-wavelength Integrating Nephelometer. Aerosols scattering properties like the scattering coefficient (σ sp), backscattering coefficient (σ bsp), scattering Ångstrom exponent (Å), backscattering ratio (b λ ) and asymmetry parameter (g λ ) were measured for the period of study. The average values of (±standard deviation) σ sp, σ bsp at 550 nm ( σ sp 550 , σ bsp 550 ) and Å(700/450) were found to be 97 (±9.2) M m−1 and 14 (±0.93) M m−1 and 1.02 (±0.3), respectively. The estimated average values of b λ and g λ at 550 nm from σ sp 550 and σ bsp 550 were 0.13 (±0.09) and 0.59 (±0.1), respectively. The maximum asymmetry parameter at 550 nm was found to be 0.63 ± 0.01 in the month of October and minimum (0.52 ± 0.03) during March, which shows the opposite trend with backscattering ratio. Significant correlation coefficients were noticed between different aerosol optical properties. The highest values of σ sp 550 were observed during weekdays whereas low values during weekends. Scattering Ångstrom exponent for the summer and winter seasons has been consistent with the input of fine mode particles from anthropogenic origin.
Keywords: Nephelometer; Scattering coefficient; Backscattering coefficient; Scattering Ångstrom exponent; Backscattering ratio and asymmetry parameter;