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Atmospheric Environment (v.68, #)

Editorial board (pp. ii).

Consecutive extreme visibility events in China during 1960–2009 by Chuanbo Fu; Jian Wu; Yanchun Gao; Deming Zhao; Zhiwei Han (pp. 1-7).

Features of consecutive extreme visibility events, such as the annual maximum duration of consecutive good visibility (≥20 km) and bad visibility (<5 km) and the annual frequency of consecutive extreme visibility events (≥3 day), and their visibility values were explored over China in recent 50-year period. Different features of consecutive extreme visibility events in large, medium and small cities were compared. According to the spatial characteristics of consecutive extreme visibility events, China can be divided into two main regions: one region extends from the north part of northern China and westwards to northwestern China and the western part of southwestern China, where consecutive good visibility events have much higher frequency than do other regions, which include the southern parts of northeastern and northern China, the middle and lower reaches of the Yangtze River and southern China. The degradation of visibility in consecutive extreme visibility events in the northern part of China is less than that in the southern part, and an increased visibility value during these events was found in the northern part of northern China. The frequency of consecutive good visibility events decreased in all cities especially after 1980, and their regression coefficients reached a minimum in small cities and a maximum in large cities.► Weaker visibility decrease in EVEs in north China than in south China.► Frequency of consecutive good visibility events decreased in all cities.► Visibility improvement in consecutive bad visibility events in northern China.

Keywords: Consecutive extreme visibility event; Annual change; China

Consecutive extreme visibility events in China during 1960–2009 by Chuanbo Fu; Jian Wu; Yanchun Gao; Deming Zhao; Zhiwei Han (pp. 1-7).

Keywords: Consecutive extreme visibility event; Annual change; China

The importance of high vehicle power for passenger car emissions by David C. Carslaw; Martin L. Williams; James E. Tate; Sean D. Beevers (pp. 8-16).

In this paper we use a quantile regression technique to explore the emissions characteristics of petrol and diesel passenger cars to reveal the importance of high vehicle power on exhaust emissions. A large database of ≈67,000 passenger cars from vehicle emission remote sensing data was used from surveys from several campaigns around the UK. Most previous remote sensing studies have focused on presenting mean emission estimates by vehicle type over time. However, as shown in the current work, considerably more insight can be gained into vehicle emission characteristics if techniques are used that can describe and model the full distribution of vehicle emissions as a function of important explanatory variables. For post-2000 model year (Euro 3–5) diesel cars it is shown that there is a strong dependence of vehicle specific power for emissions of NO_x that was absent in earlier models and is absent for other pollutants such as CO, hydrocarbons and ‘smoke’. Furthermore, we also find a stronger dependence on vehicle specific power for older catalyst-equipped petrol vehicles (Euro 1/2) on emissions of NO_x that is less important for other emissions such as CO and hydrocarbons. Moreover, it is shown that while the rated maximum power output of petrol cars has remained almost constant over the past 15–20 years, the power output from diesel cars has increased markedly by about 50%. These results suggest that changes to vehicle technology, driving conditions and driver behaviour have become more important determinants of passenger car NO_x emissions in recent years and may help explain why urban ambient concentrations of NO_x have not decreased as much as anticipated.► Higher vehicle power increases NO_x emissions from modern diesel cars. ► Older-catalyst-equipped vehicles show same effect. ► Power of diesel cars has increased markedly over past 20 year, not so petrol. ► Quantile regression methods very useful for exploring full distribution of emissions.

Keywords: Remote sensing; Vehicle specific power; Vehicle emissions; Air pollution

The importance of high vehicle power for passenger car emissions by David C. Carslaw; Martin L. Williams; James E. Tate; Sean D. Beevers (pp. 8-16).

Keywords: Remote sensing; Vehicle specific power; Vehicle emissions; Air pollution

Concentration and risk assessment of phthalates present in indoor air from newly decorated apartments by X.Q. Pei; M. Song; M. Guo; F.F. Mo; X.Y. Shen (pp. 17-23).

Phthalate esters (PAEs) are ubiquitous in the indoor environment, owing to their use in consumer products. People spend a considerable amount of time indoors. As a result, human exposure to indoor contaminants is of great concern. People are exposed to phthalates through inhalation and dermal absorption of indoor air. In this study, the concentrations, characteristics and carcinogenic risks of gas-phase and particle-phase phthalates in indoor air from bedroom, living room and study room of 10 newly decorated apartments in Hangzhou, China were first investigated. The mean concentration of phthalates (gas-phase and particle-phase) present in household air was 12 096.4 ng m⁻³, of which diethyl phthalate (DEP), butylbenzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP) were the most abundant compounds with concentrations of 2290 ng m⁻³, 3975 ng m⁻³ and 2437 ng m⁻³, respectively, totally accounting for 72.0% of ∑₆PAEs. Contamination levels of phthalates varied in different compartments. The concentration of phthalates was the highest 17 363.7 ng m⁻³ in living room, followed with 11 389.5 ng m⁻³ in study room, and the lowest 9739.1 ng m⁻³ in bedroom. It was also found that phthalates mainly accumulated in gaseous form in household air. DEHP posed the greatest health risk to children aged 1–2. Carcinogenic risk of DEHP was evaluated to be 3.912 × 10⁻⁵, and was 39 times higher than the limit set by the U.S. EPA.► Characteristic and risk of phthalates in indoor air were first investigated. ► The concentration of phthalates is 12 096 ng m⁻³ in newly decorated apartments China. ► Phthalates are mostly in gaseous form and DEP, BBP and DEHP are major pollutants. ► The overall pollution trend is the living room > study room > bedroom. ► Exposure to DEHP is mostly harmful to babies aged 1–2 and a risk value is 3.912 × 10⁻⁵.

Keywords: Phthalate esters; Indoor air; Concentrations; Carcinogenic risk

Concentration and risk assessment of phthalates present in indoor air from newly decorated apartments by X.Q. Pei; M. Song; M. Guo; F.F. Mo; X.Y. Shen (pp. 17-23).

Keywords: Phthalate esters; Indoor air; Concentrations; Carcinogenic risk

Impact of grid resolution on the predicted fine PM by a regional 3-D chemical transport model by C. Fountoukis; Dh. Koraj; H.A.C. Denier van der Gon; P.E. Charalampidis; C. Pilinis; S.N. Pandis (pp. 24-32).

This study examines the role of horizontal grid resolution on the performance of the regional three dimensional chemical transport model (CTM) PMCAMx. Two cases were investigated. First, the model was applied over the Northeastern United States with grid resolutions of 36 and 12 km during both a summer and a winter period. In this case the emission inventory was simply interpolated from the low resolution version. In the second case a multi-scale 36/4 km grid resolution is used over Western Europe with high resolution (4 × 4 km) emissions. The improvement in model predictions with the fine grid is modest during the summer and more significant during wintertime at both domains. Major differences are predicted mostly for primary (organics and black carbon (BC)) rather than secondary (e.g. sulfate) species. The use of high grid resolution decreases the bias for BC concentration by more than 30% in the Northeastern US during wintertime. In the Megacity of Paris, using high resolution emissions and a 4-km grid decreases the fractional bias for organic aerosol (OA) from 80% to 60% in the city center and produces much larger spatial concentration gradients in the domain as compared to the emissions being interpolated. These results suggest that future work should combine high grid resolution with high resolution emissions, taking into consideration, though, that the grid resolution is not currently the major source of the discrepancies between model predictions and observations.► Quantification of the error introduced in urban and regional fine PM simulations by model and emission inventory resolution. ► Resolution is important for primary PM components and winter. ► Grid resolution is not the major problem in current regional scale simulations.

Keywords: Grid resolution; Regional CTM; Megacity; Black carbon; Organic aerosol

Daily and hourly sourcing of metallic and mineral dust in urban air contaminated by traffic and coal-burning emissions by T. Moreno; A. Karanasiou; F. Amato; F. Lucarelli; S. Nava; G. Calzolai; M. Chiari; E. Coz; B. Artíñano; J. Lumbreras; R. Borge; E. Boldo; C. Linares; A. Alastuey; X. Querol; W. Gibbons (pp. 33-44).

A multi-analytical approach to chemical analysis of inhalable urban atmospheric particulate matter (PM), integrating particle induced X-ray emission, inductively coupled plasma mass spectrometry/atomic emission spectroscopy, chromatography and thermal–optical transmission methods, allows comparison between hourly (Streaker) and 24-h (High volume sampler) data and consequently improved PM chemical characterization and source identification. In a traffic hot spot monitoring site in Madrid (Spain) the hourly data reveal metallic emissions (Zn, Cu, Cr, Fe) and resuspended mineral dust (Ca, Al, Si) to be closely associated with traffic flow. These pollutants build up during the day, emphasizing evening rush hour peaks, but decrease (especially their coarser fraction PM_2.5–10) after nocturnal road washing. Positive matrix factorization (PMF) analysis of a large Streaker database additionally reveals two other mineral dust components (siliceous and sodic), marine aerosol, and minor, transient events which we attribute to biomass burning (K-rich) and industrial (incinerator?) Zn, Pb plumes. Chemical data on 24-h filters allows the measurement of secondary inorganic compounds and carbon concentrations and offers PMF analysis based on a limited number of samples but using fuller range of trace elements which, in the case of Madrid, identifies the continuing minor presence of a coal combustion source traced by As, Se, Ge and Organic Carbon. This coal component is more evident in the city air after the change to the winter heating season in November. Trace element data also allow use of discrimination diagrams such as V/Rb vs. La/Ce and ternary plots to illustrate variations in atmospheric chemistry (such as the effect of Ce-emissions from catalytic converters), with Madrid being an example of a city with little industrial pollution, recently reduced coal emissions, but serious atmospheric contamination by traffic emissions.► We apply a multi-analytical approach to the chemical characterization of urban air. ► City traffic controls hourly variations in metallic emissions and mineral dust. ► Winter coal combustion is traced by atmospheric As, Se, Ge and Organic Carbon. ► Traffic exhaust enriches city air in Cerium. ► Applying PMF to both hourly (PIXE) and daily (ICP) data improves source apportionment.

Keywords: Atmospheric metal; Mineral dust; Madrid; Cerium; Arsenic; PMF

Variations in atmospheric Carbon Dioxide and its association with rainfall and vegetation over India by Yogesh K. Tiwari; J.V. Revadekar; K. Ravi Kumar (pp. 45-51).

In this paper we have studied variability and growth rate of surface observed atmospheric Carbon Dioxide (CO₂) concentrations over Cape Rama, west coast of India and its association with rainfall and vegetation over this region. Cape Rama is a maritime site which experiences a seasonal reversal wind pattern receiving air masses having marine (continental) signatures during summer (winter) monsoon season. This study reveals that summer monsoon (JJAS) precipitation and monthly values of atmospheric CO₂ concentration during the season are well correlated. Negative correlations are seen with CO₂ concentrations of concurrent months of the season as well as subsequent months. However the magnitudes of correlation coefficients are decreased till hot pre-monsoon season (MAM). Annual cycle and interannual variability show negative relationship between CO₂ concentration and vegetation over the region. CO₂ concentration shows increasing trend and NDVI shows decreasing trend. However, the magnitude of increasing trend of CO₂ concentration is higher. Amplitude of decreasing phase of vegetation is higher than the amplitude of increasing phase. Though the results show certain link between CO₂ and climate variability, further examination with dense and longer data may be needed to confirm the result.► CO₂ variation in relation to changes in rainfall-vegetation were studied over India. ► Rainfall and monthly mean CO₂ concentrations are well correlated. ► Negative correlation is seen between CO₂ concentration and vegetation. ► CO₂ shows higher magnitude increasing trend than the decreasing trend of NDVI.

Keywords: Atmospheric CO; ₂; Rainfall; Vegetation; Cape Rama India

Variations in atmospheric Carbon Dioxide and its association with rainfall and vegetation over India by Yogesh K. Tiwari; J.V. Revadekar; K. Ravi Kumar (pp. 45-51).

Keywords: Atmospheric CO; ₂; Rainfall; Vegetation; Cape Rama India

New Directions: Satellite driven PM_2.5 exposure models to support targeted particle pollution health effects research by Yang Liu (pp. 52-53).

A study of dust radiative feedback on dust cycle and meteorology over East Asia by a coupled regional climate-chemistry-aerosol model by Zhiwei Han; Jiawei Li; Weidong Guo; Zhe Xiong; Wu Zhang (pp. 54-63).

An online coupled regional climate-chemistry-aerosol model was utilized to investigate the dust direct radiative feedbacks on dust deflation, transport and meteorological elements in March 2010, when a severe dust storm originated from the Gobi desert near the China–Mongolia border swept across most areas of East Asia during the period of 19–22 March. The predicted meteorology and aerosol concentration agree generally well with observations, and it clearly shows that the predictions of both dust concentration and meteorological elements with dust radiative feedback are closer to observation than that without feedback, suggesting the superiority of on-line coupled model in chemical and climate predictions. The direct radiative forcing by dust aerosol caused significant reductions in ground temperature and wind speed in dust deflation region, with maximums up to −7 °C and −4.0 m s⁻¹, respectively. The reduced wind speed and increased atmospheric stability resulted in smaller dust emission and weakened vertical diffusion, and consequently less dust aerosol in upper levels transported further downwind. While the shortwave radiative forcing dominated over longwave forcing in the daytime, leading to decreases of surface air temperature and wind speed, in the nighttime, the warming effect of longwave forcing dominated, causing increases of air temperature and wind speed up to 1 °C and 1 m s⁻¹, respectively, in the dust deflation region. The variation of meteorology during the dust storm period at a rural site (Yuzhong) downwind of the Gobi desert exhibited an evident decrease in surface air temperature due to the dust radiative forcing. In terms of monthly mean, the dust radiative forcing caused a surface cooling of −0.6 to −1.0 °C over wide areas from west China to northern parts of east China and the Korean peninsula, with maximums in the middle reaches of the Yellow River and portions of northeast China. Concurrently, precipitation decreased by 0.1–0.6 mm day⁻¹ in the middle reaches of the Yangtze River and large areas of north China, and alternating bands of increasing and decreasing precipitation (∼1 mm day⁻¹) occurred in south China.► Online coupled model can improve predictions of both dust cycle and meteorology. ► Dust radiative forcing (RF) largely reduced surface air temperature (AT) and wind speed (WS) in desert. ► Dust RF caused AT and WS decreases in lower troposphere and increases in middle troposphere. ► Longwave RF increased nighttime AT and WS, and partly offset daytime shortwave RF. ► Dust RF caused distinct decreases in surface AT and precipitation in northern parts of east China.

Keywords: Mineral dust; Meteorological elements; Radiative effects; Cooling; Warming; Dust–climate interaction

Bayesian analysis of climate change effects on observed and projected airborne levels of birch pollen by Yong Zhang; Sastry S. Isukapalli; Leonard Bielory; Panos G. Georgopoulos (pp. 64-73).

A Bayesian framework is presented for modeling effects of climate change on pollen indices such as annual birch pollen count, maximum daily birch pollen count, start date of birch pollen season and the date of maximum daily birch pollen count. Annual mean CO₂ concentration, mean spring temperature and the corresponding pollen index of prior year were found to be statistically significant accounting for effects of climate change on four pollen indices. Results suggest that annual productions and peak values from 2020 to 2100 under different scenarios will be 1.3–8.0 and 1.1–7.3 times higher respectively than the mean values for 2000, and start and peak dates will occur around two to four weeks earlier. These results have been partly confirmed by the available historical data. As a demonstration, the emission profiles in future years were generated by incorporating the predicted pollen indices into an existing emission model.► A Bayesian framework is presented to model climate change effect on birch pollen. ► Airborne pollen levels are estimated based on observed and projected climate factors. ► Pollen emission fluxes are generated using the output from Bayesian model. ► Pollen season tends to start earlier with rising airborne pollen levels in the future.

Keywords: Climate change; Birch; Pollen; Bayesian analysis

Bayesian analysis of climate change effects on observed and projected airborne levels of birch pollen by Yong Zhang; Sastry S. Isukapalli; Leonard Bielory; Panos G. Georgopoulos (pp. 64-73).

Keywords: Climate change; Birch; Pollen; Bayesian analysis

Assessment of air quality improvement effect under the National Total Emission Control Program during the Twelfth National Five-Year Plan in China by Wenbo Xue; Jinnan Wang; Hao Niu; Jintian Yang; Baoping Han; Yu Lei; Hanli Chen; Chunlai Jiang (pp. 74-81).

The National Total Emission Control (NTEC) Program will continue to be implemented during the 12th Five-Year Plan period (FYP, 2011–2015) in China. Two pollutants (SO₂ and NO_x) are covered by NTEC, of which NO_x is a newly added pollutant under control. NTEC requires that the national total SO₂ and NO_x emissions be reduced by 8% and 10% respectively in 2015 from the levels of 2010. Annual mean SO₂, NO₂, and PM_2.5 (sulfates and nitrates) concentrations in 2010 and 2015 were simulated with the Community Multiscale Air Quality (CMAQ) model based on the national source census data and reduction targets in the NTEC Program. Reliability of the simulation results was verified by ground-based observation data and satellite remote sensing data in 113 national key monitoring cities. The air quality improvement from NTEC was also assessed quantitatively. The assessment results indicated that the average SO₂ and NO₂ concentrations in all cities in 2015 would be reduced by 9.28% and 10.61% respectively from the 2010 levels. The number of cities whose annual average SO₂ and NO₂ concentrations fail to comply with the national ambient air quality standard will be reduced by 9 and 27 respectively. The PM_2.5 simulation results demonstrated that the average sulfate and nitrate concentrations in all cities in 2010 accounted for 20.28% and 17.45% of the PM_2.5 respectively. Having considered the emissions reduction effect of SO₂ and NO_x only, the average sulfate, nitrate, and PM_2.5 concentrations in all cities in 2015 will be reduced by 6.25%, 6.04%, and 2.23% respectively from the levels of 2010. However, the annual mean PM_2.5 concentration will still exceed the national standard in 77.18% of the cities in China in 2015. These percentages would be as high as 99.70% based on U.S. national standards and 100% based on the World Health Organization's guideline value.► We confirm the accuracy of CMAQ model using Satellite-ground Observed Data. ► We assess air quality improvement effect under NTEC program conduct with CMAQ. ► The cities where annual mean SO₂ concentration over limit reduce by 9 under NTEC. ► The cities where annual mean NO₂ concentration over limit reduce by 27 under NTEC. ► The cities where annual mean PM_2.5 concentration over limit reduce by 7 under NTEC.

Keywords: Emission control in China; CMAQ; National standard; World Health Organization

Comparison of fine particles emissions of light-duty gasoline vehicles from chassis dynamometer tests and on-road measurements by Tiezhu Li; Xudong Chen; Zhenxing Yan (pp. 82-91).

Fine particles are highly related to human health, especially ultrafine particles and nanoparticles. The mass of emissions from a gasoline vehicle is relatively lower than that of a diesel vehicle, but the number of gasoline vehicles in China is so huge that the number of fine particles can't be ignored. An on-board measurement system was established to measure the instantaneous number and mass size distributions of fine particles emitted from a light-duty gasoline vehicle under a real-world driving condition. The exhaust gas was sampled from the inside of the tailpipe. Measurements were carried out using a light-duty gasoline vehicle for goods on a chassis dynamometer and on urban streets in a downtown area of Nanjing. Size and time resolved data were obtained from an Engine Exhaust Particle Sizer (EEPS). The system was operated under the New European Driving Cycle (NEDC) and steady-state speed tests. The comparisons of size distribution and number concentration (NC) in different driving cycles in the real-world with the results from the chassis dynamometer are shown. The time proportion of operating modes in NEDC is different from that on real urban roads. The particle sizes for the NCs obey a bimodal distribution from the on-road data with mode sizes of 10.8 nm and 39.2 nm, while those from the chassis dynamometer tests obey a unimodal distribution with a mode size of 10.8 nm. The maximum NCs of particles were increased as the vehicle operating modes changed from idling, cursing to deceleration and acceleration from the on-board measurements, while compared to that from the on-board measurements, the maximum concentrations at the mode size were however in different order and the cruising mode became the second highest peak instead of the deceleration mode. The ratios of the NCs from the chassis dynamometers to that from on-road data in the speed of 15 km h⁻¹, 32 km h⁻¹, and 50 km h⁻¹ are 2.78, 2.19, and 0.48, respectively. Similarly for the mass concentration the ratios are 0.19, 0.17, and 0.009, respectively. The acceleration in the interval of 0.6–0.9 m s⁻² has the greatest influence on the NC in on-road measurements, while the acceleration of 0.52 m s⁻² has the most significant impact on the NC in the chassis dynamometer tests. The vehicle load increases the total number and mass concentration in a small range, showing no significant impact on particles size distribution especially the nanoparticles. The comparison shows that the fine particle emissions are indeed different between the NEDC and the on-road measurements in Nanjing. The differences show that the fine particles emission on the real road can't be represented well by the results in the NEDC, and the corresponding errors should be in consideration when the vehicle emissions from the NEDC are applied. The study makes us clear that the fine particles emission characteristics of the light-duty vehicle on the urban roads are really different with that in the NEDC.► A new on-board system for measuring the instantaneous emission of fine particles was set up. ► More fine particles in nucleic mode during the NEDC were emitted than those during the on-road measurements. ► The number concentration of particle obeys a bimodal distribution on the urban streets. ► The number concentration of particle obeys a unimodal distribution on the chassis dynamometer test. ► Hard acceleration with higher speed produced more fine particles.

Keywords: Fine particle emission; Size distribution; On-road measurement; Chassis dynamometer test; Light-duty gasoline vehicle

Comparison of fine particles emissions of light-duty gasoline vehicles from chassis dynamometer tests and on-road measurements by Tiezhu Li; Xudong Chen; Zhenxing Yan (pp. 82-91).

Keywords: Fine particle emission; Size distribution; On-road measurement; Chassis dynamometer test; Light-duty gasoline vehicle

A new approach for estimation of the effect of NO_x emission reduction on roadside NO₂ concentration in Tokyo by Hideto Takekawa; Satoru Chatani; Akiyoshi Ito (pp. 92-102).

The mean NO₂/NO_x ratios of vehicle emission, the mean duration time of NO reaction with O₃ and background concentrations at the five most polluted roadside stations in Tokyo are estimated statistically using monitoring data at both roadside sites and urban background sites. These statistics are then used to categorize roadside NO₂ into three components; NO₂ emission from vehicles (primary NO₂), oxidation of NO by O₃ (secondary NO₂) and background NO₂ (BG NO₂). Secondary NO₂ and BG NO₂ make a greater contribution to the high NO₂ concentrations in spring and summer. On the other hand, BG NO₂ contributes the dominant portion to high NO₂ concentrations in winter. The effects of vehicle NO_x emission reduction on the concentration of primary, secondary and BG NO₂ are evaluated using an NO₂ emission reduction scenario, an oxidation model proposed in this study and an air quality simulation, respectively. It is predicted that the shift to vehicles meeting the stringent emission regulation beginning in 2009 will lower the roadside NO₂ concentration due mainly to the large decrease in secondary NO₂. On the other hand, the reduction of NO_x in vehicle emissions results in a smaller decrease in roadside NO₂ in winter.Display Omitted► Roadside NO₂ concentrations are apportioned into three sources. ► Secondary NO₂ and background NO₂ make a greater contribution in spring and summer. ► Background NO₂ contributes the dominant portion in winter. ► The NO oxidation model is constructed to predict secondary NO₂ concentration. ► Vehicle NO_x emission reduction makes secondary NO₂ concentration lower largely.

Keywords: Roadside; Nitrogen oxides; Ozone; Emission reduction; Environmental assessment; Tokyo

A new approach for estimation of the effect of NO_x emission reduction on roadside NO₂ concentration in Tokyo by Hideto Takekawa; Satoru Chatani; Akiyoshi Ito (pp. 92-102).

Keywords: Roadside; Nitrogen oxides; Ozone; Emission reduction; Environmental assessment; Tokyo

A regional assessment of marine vessel PM_2.5 impacts in the U.S. Pacific Northwest using a receptor-based source apportionment method by Robert A. Kotchenruther (pp. 103-111).

This work reports results from a receptor-based source apportionment analysis using the Positive Matrix Factorization (PMF) model on chemically speciated PM_2.5 data from 36 urban and rural monitoring sites within the U.S. Pacific Northwest. The approach taken is to model each site independently, treats monitor datasets with a common data preparation protocol, and uses a common modeling protocol. Complementary data from two monitoring networks, the urban Chemical Speciation Network (CSN) and rural Interagency Monitoring of Protected Visual Environments (IMPROVE) Network, was modeled for the period of 2007–2011. 15 different factor types were found for CSN sites and 17 for IMPROVE sites, however many factors occurred at only a few locations. Only 3 factor types were common in both networks: sulfate/sulfur rich, nitrate rich, and soil. However, for coastal and near coastal monitoring sites there were three additional factors common in both networks: sea salt, aged sea salt, and residual fuel oil combustion (RFO). This work presents annual average PM_2.5 mass impacts for all sites and factors found and the results for RFO are explored in greater depth. The association between RFO results and commercial marine vessel emissions is made based on similarities between factor chemical profiles and published emissions profiles, comparisons with emissions inventories, and the similarity in the spatial extent of RFO factor locations to that of the other marine aerosols identified in this study, sea salt and aged sea salt. All 14 monitoring sites with marine vessel RFO factors showed a seasonal cycle of mass impacts, with lower impacts in winter months (monthly average PM_2.5 between 0.1 μg m⁻³ and 0.9 μg m⁻³ in January) and higher impacts in summer months (monthly average PM_2.5 between 0.3 μg m⁻³ and 2.7 μg m⁻³ in August). These results set a baseline to measure progress in emissions reductions that are expected from implementation of the North American Emissions Control Area (ECA) beginning in August 2012.► PM_2.5 source apportionment was performed for 36 sites in the northwest U.S. ► Residual fuel oil factors at 14 locations were linked to marine vessel emissions. ► Monthly average PM_2.5 impacts from marine vessel emissions are quantified. ► Results are just prior to the start of the North American Emissions Control Area. ► Results set a baseline to measure progress in emissions reductions.

Keywords: PM; _2.5; Marine vessel emissions; Positive matrix factorization; Source apportionment; Residual fuel oil; Emissions control area

A regional assessment of marine vessel PM_2.5 impacts in the U.S. Pacific Northwest using a receptor-based source apportionment method by Robert A. Kotchenruther (pp. 103-111).

Keywords: PM; _2.5; Marine vessel emissions; Positive matrix factorization; Source apportionment; Residual fuel oil; Emissions control area

New Directions: Climatediversity: A new paradigm for climate science by Paul John Beggs (pp. 112-113).

Heterogeneous reaction of particle-associated triphenylene with NO₃ radicals by Yang Zhang; Jinian Shu; Changgeng Liu; Yuanxun Zhang; Bo Yang; Jie Gan (pp. 114-119).

Although heterogeneous reactions of polycyclic aromatic hydrocarbons (PAHs) with atmospheric oxidants may be important loss processes for PAHs, our understanding of their kinetics and products is incomplete. The study of heterogeneous reaction of suspended triphenylene particles with NO₃ radicals is undertaken in a flow-tube-reactor. The time-of-flight mass spectra of particulate triphenylene and its nitration products are obtained with vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer. 1- and 2-nitrotriphenylene are identified by GC–MS analysis of the products formed from the reaction of NO₃ radicals with triphenylene coated on the inner bottom surface of a conical flask. 1-Nitrotriphenylene is formed in larger yield than 2-nitrotriphenylene. This phenomenon is different from what had been observed in previous studies of the gas-phase triphenylene nitration, showing that 2-nitrotriphenylene is the major nitration product. The experimental results may reveal the discrepancies between heterogeneous and homogeneous nitrations of triphenylene.

Keywords: Triphenylene; NO; ₃; radical; Heterogeneous reaction; Aerosol mass spectrometer

Heterogeneous reaction of particle-associated triphenylene with NO₃ radicals by Yang Zhang; Jinian Shu; Changgeng Liu; Yuanxun Zhang; Bo Yang; Jie Gan (pp. 114-119).

Keywords: Triphenylene; NO; ₃; radical; Heterogeneous reaction; Aerosol mass spectrometer

Emissions estimates of PAH from biomass fuels used in rural sector of Indo-Gangetic Plains of India by D.P. Singh; Ranu Gadi; T.K. Mandal; T. Saud; M. Saxena; S.K. Sharma (pp. 120-126).

Polycyclic aromatic hydrocarbons (PAHs) are of special interest due to their carcinogenicity, and ubiquitous presence in the environment. Emissions of PAH vary with use of biomass fuels. In this study, the experimentally determined emission factors and emission estimates of PAH emitted from biomass fuels (dung cake, fuelwood and crop residue) from rural household of six states (Delhi, Uttar Pradesh, Punjab, Haryana, Uttarakhand and Bihar) over the IGP, India, are presented. The gaseous phase and particulate phase PAHs emissions are simultaneously determined from various biomass fuels. The average emission factors of total PAHs from dung cakes, fuelwood and crop residue over the IGP, India are estimated as 59.5 ± 19.9 mg kg⁻¹, 52.5 ± 19.6 mg kg⁻¹ and 40.9 ± 15.2 mg kg⁻¹ respectively. The emission factor of particulate phase PAHs (56.5 mg kg⁻¹, 45.3 mg kg⁻¹ and 35.8 mg kg⁻¹) was found higher as compared to gaseous phase PAHs (3.1 mg kg⁻¹, 7.2 mg kg⁻¹ and 5.1 mg kg⁻¹) from dung cakes, fuel-wood and crop residue, respectively. Anthracene, fluoranthene, pyrene, benzo[a]anthracene and chrysene are predominant PAHs in all biomass fuels. The emission estimates of PAH over IGP are determined as 2.95 ± 0.98 Gg yr⁻¹, 3.13 ± 1.08 Gg yr⁻¹ and 0.66 ± 0.26 Gg yr⁻¹ from dung cakes, fuelwood and crop residue, respectively.► Determination of EF of PAHs from biomass fuels in the laboratory. ► Simultaneous determination of gaseous and particulate phase PAHs. ► State-wise EF of total PAHs from residential fuels over IGP, India. ► Budget estimates of PAHs from residential fuels over six states in IGP, India.

Keywords: Indo-Gangetic Plains; Biomass fuels; Gaseous phase PAH; Particulate phase PAH; Emission factors; Budget estimates

Emissions estimates of PAH from biomass fuels used in rural sector of Indo-Gangetic Plains of India by D.P. Singh; Ranu Gadi; T.K. Mandal; T. Saud; M. Saxena; S.K. Sharma (pp. 120-126).

Keywords: Indo-Gangetic Plains; Biomass fuels; Gaseous phase PAH; Particulate phase PAH; Emission factors; Budget estimates

Urban street canyons: Coupling dynamics, chemistry and within-canyon chemical processing of emissions by Vivien Bianca Bright; William James Bloss; Xiaoming Cai (pp. 127-142).

Street canyons, formed by rows of buildings in urban environments, are associated with high levels of atmospheric pollutants emitted primarily from vehicles, and substantial human exposure. The street canyon forms a semi-enclosed environment, within which emissions may be entrained in a re-circulatory system; chemical processing of emitted compounds alters the composition of the air vented to the overlying boundary layer, compared with the primary emissions. As the prevailing atmospheric chemistry is highly non-linear, and the canyon mixing and predominant chemical reaction timescales are comparable, the combined impacts of dynamics and chemistry must be considered to quantify these effects. Here we report a model study of the coupled impacts of dynamical and chemical processing upon the atmospheric composition in a street canyon environment, to assess the impacts upon air pollutant levels within the canyon, and to quantify the extent to which within-canyon chemical processing alters the composition of canyon outflow, in comparison to the primary emissions within the canyon. A new model for the simulation of street canyon atmospheric chemical processing has been developed, by integrating an existing Large-Eddy Simulation (LES) dynamical model of canyon atmospheric motion with a detailed chemical reaction mechanism, a Reduced Chemical Scheme (RCS) comprising 51 chemical species and 136 reactions, based upon a subset of the Master Chemical Mechanism (MCM). The combined LES–RCS model is used to investigate the combined effects of mixing and chemical processing upon air quality within an idealised street canyon. The effect of the combination of dynamical (segregation) and chemical effects is determined by comparing the outputs of the full LES–RCS canyon model with those obtained when representing the canyon as a zero-dimensional box model (i.e. assuming mixing is complete and instantaneous). The LES–RCS approach predicts lower (canyon-averaged) levels of NO_x, OH and HO₂, but higher levels of O₃, compared with the box model run under identical chemical and emissions conditions. When considering the level of chemical detail implemented, segregation effects were found to reduce the error introduced by simplifying the reaction mechanism. Chemical processing of emissions within the canyon leads to a significant increase in the O_x flux from the canyon into the overlying boundary layer, relative to primary emissions, for the idealised case considered here. These results demonstrate that within-canyon atmospheric chemical processing can substantially alter the concentrations of pollutants injected into the urban canopy layer, compared with the raw emission rates within the street canyon. The extent to which these effects occur is likely to be dependent upon the nature of the domain (canyon aspect ratio), prevailing meteorology and emission/pollution scenario considered.► The extent of chemical processing of emissions within a street canyon is assessed. ► Within-canyon processing leads to increased O₃ and reduced NO_x in canyon outflow. ► The extent of processing is dependent upon the chemical detail and dynamics treatment. ► Simplified approaches systematically underestimate within canyon oxidant formation.

Keywords: Street canyons; Air pollution; Large-Eddy Simulation; NO; _x; Ozone

Urban street canyons: Coupling dynamics, chemistry and within-canyon chemical processing of emissions by Vivien Bianca Bright; William James Bloss; Xiaoming Cai (pp. 127-142).

Keywords: Street canyons; Air pollution; Large-Eddy Simulation; NO; _x; Ozone

Responses of lung cells to realistic exposure of primary and aged carbonaceous aerosols by Lisa Künzi; Peter Mertes; Sarah Schneider; Natalie Jeannet; Carmela Menzi; Josef Dommen; Urs Baltensperger; André S.H. Prévôt; Matthias Salathe; Markus Kalberer; Marianne Geiser (pp. 143-150).

Diesel exhaust and wood burning are important sources of ambient atmospheric particles due to increasing numbers of diesel cars and the importance of wood as a source of renewable energy. Inhalation is the predominant route of entry and uptake for fine and ultrafine particles into the body. Health effects of atmospheric particles are still not completely understood. There is consistent evidence from epidemiology that particle exposure contributes to respiratory and cardiovascular diseases.This study aimed at examining acute responses of airway epithelial cells and luminal macrophages after exposure to freshly emitted and photochemically aged carbonaceous aerosols under realistic atmospheric conditions. In addition to a bronchial epithelial cell line advanced cell cultures namely fully differentiated respiratory epithelia and primary surface macrophages were used.Our results demonstrate that a single exposure of the cells to realistic particle doses of 0.3–3 ng diesel or 3–9 ng wood aerosol per cm² cell surface induces small, particle-specific responses. The release of interleukin-6 and -8 was found to be decreased in differentiated airway epithelia but not in the other cell models studied. Aerosol exposure decreased macrophage phagocytic activity by 45–90%. Cell and tissue integrity remained unaffected. Overall, primary and aged particles from the same combustion induced similar responses in the cell models tested, whereby particles from diesel exhaust affected the cells more than those from wood combustion.► Study on effects of wood and diesel combustion particles on lung cells in-vitro. ► Realistic exposure of cells to freshly emitted and atmospherically aged particles. ► Particle exposure induced subtle changes in cellular functions. ► Primary and aged particles from the same combustion induced similar effects.

Keywords: Combustion-derived particles; Lungs; Epithelial cells; Macrophages; Primary aerosol; Photochemically aged aerosolAbbreviations; ALI; air–liquid interface; BAL; bronchoalveolar lavage; BC; black carbon; DPBS; Dulbecco's phosphate-buffered saline; IL; interleukin; LDH; lactate dehydrogenase; LM; light microscopy; MCP-1; monocyte chemotactic protein-1; NO; _x; nitrogen oxides; OM; organic mass; PBS; phosphate-buffered saline; PSL; polystyrene latex; RH; relative humidity; TEM; transmission electron microscopy; TNF-α; tumor necrosis factor-alpha

Water-based condensation particle counters comparison near a major freeway with significant heavy-duty diesel traffic by Eon S. Lee; Andrea Polidori; Michael Koch; Philip M. Fine; Ahmed Mehadi; Donald Hammond; Jeffery N. Wright; Antonio. H. Miguel; Alberto Ayala; Yifang Zhu (pp. 151-161).

This study compares the instrumental performance of three TSI water-based condensation particle counter (WCPC) models measuring particle number concentrations in close proximity (15 m) to a major freeway that has a significant level of heavy-duty diesel traffic. The study focuses on examining instrument biases and performance differences by different WCPC models under realistic field operational conditions. Three TSI models (3781, 3783, and 3785) were operated for one month in triplicate (nine units in total) in parallel with two sets of Scanning Mobility Particle Sizer (SMPS) spectrometers for the concurrent measurement of particle size distributions. Inter-model bias under different wind directions were first evaluated using 1-min raw data. Although all three WCPC models agreed well in upwind conditions (lower particle number concentrations, in the range of 10³–10⁴ particles cm⁻³), the three models' responses were significantly different under downwind conditions (higher particle number concentrations, above 10⁴ particles cm⁻³). In an effort to increase inter-model linear correlations, we evaluated the results of using longer averaging time intervals. An averaging time of at least 15 min was found to achieve R² values of 0.96 or higher when comparing all three models. Similar results were observed for intra-model comparisons for each of the three models. This strong linear relationship helped identify instrument bias related to particle number concentrations and particle size distributions. The TSI 3783 produced the highest particle counts, followed by TSI 3785, which reported 11% lower during downwind conditions than TSI 3783. TSI 3781 recorded particle number concentrations that were 24% lower than those observed by TSI 3783 during downwind condition. We found that TSI 3781 underestimated particles with a count median diameter less than 45 nm. Although the particle size dependency of instrument performance was found the most significant in TSI 3781, both models 3783 and 3785 showed somewhat size dependency. In addition, within each tested WCPC model, one unit was found to count significantly different and be more sensitive to particle size than the other two. Finally, exponential regression analysis was used to numerically quantify instrumental inter-model bias. Correction equations are proposed to adjust the TSI 3781 and 3785 data to the most recent model TSI 3783.► Three TSI WCPC models (9 units) were compared for one month near a major freeway. ► The 3 models' responses were significantly different under downwind conditions. ► All units showed somewhat size dependency especially for smaller ultrafine particles. ► TSI model 3783 provides relatively consistent data among studied models.

Keywords: WCPC; Ultrafine particles; Traffic emissions; Freeway

Multi-scale modeling of roadway air quality impacts: Development and evaluation of a Plume-in-Grid model by Régis Briant; Christian Seigneur (pp. 162-173).

Eulerian three-dimensional (3D) grid-based models are widely used in air quality modeling. In such models, emissions are instantaneously diluted within the grid cells and, therefore, the near-source impacts of large point and line sources cannot be properly resolved. Plume-in-Grid models (PinG) use a subgrid-scale treatment to better represent local source contributions in an Eulerian grid-based simulation. PinG models already exist for point sources. However, modeling emissions from roadway traffic with point sources implies a very large computational burden. We present here a new PinG model that uses a Gaussian line source model, better suited than point sources to model roadway traffic emissions, embedded within an Eulerian model. The model is evaluated with a large dataset of nitrogen dioxide (NO₂) concentrations over a 800 km road network. The PinG model leads to greater NO₂ concentrations and shows better performance than the Eulerian model.► Development of a PinG model for roadway. ► Evaluation of the model. ► Sensitivity study.

Keywords: Plume-in-Grid model; Line source; Traffic emissions; Polyphemus; Polair3D; Subgrid-scale

Multi-scale modeling of roadway air quality impacts: Development and evaluation of a Plume-in-Grid model by Régis Briant; Christian Seigneur (pp. 162-173).

Keywords: Plume-in-Grid model; Line source; Traffic emissions; Polyphemus; Polair3D; Subgrid-scale

The regional atmospheric chemistry mechanism, version 2 by Wendy S. Goliff; William R. Stockwell; Charlene V. Lawson (pp. 174-185).

The Regional Atmospheric Chemistry Mechanism (RACM) is a gas-phase chemical mechanism that is widely used for the modeling of regional atmospheric chemistry. Much new data has been published since the original RACM was completed (Stockwell et al., 1997). The RACM mechanism was updated to create the Regional Atmospheric Chemistry Mechanism, version 2 (RACM2). Like the RACM1 mechanism, the RACM2 mechanism is designed to simulate remote to polluted conditions from the Earth's surface through the upper troposphere. The RACM2 mechanism includes updated reaction schemes, rate constants and product yields. It has been tested against environmental chamber data and compared with previous RACM scenario simulations. The aromatic chemistry was expanded to include a greater number of species with highly revised reaction schemes. The reaction mechanism for isoprene was expanded to include a more explicit treatment of methyl vinyl ketone. Alcohols were speciated to more accurately reflect peroxy–peroxy reactions in the remote atmosphere. Acetone was speciated due to its importance in the upper troposphere.► The RACM2 mechanism includes updated reactions, rate constants and product yields. ► It has been tested against environmental chamber data. ► The aromatic chemistry was expanded to include a greater number of species. ► The reaction mechanism for isoprene was expanded.

Keywords: Atmospheric chemistry; Chemical mechanisms; Air quality modeling; Ozone; Acid deposition

The regional atmospheric chemistry mechanism, version 2 by Wendy S. Goliff; William R. Stockwell; Charlene V. Lawson (pp. 174-185).

Keywords: Atmospheric chemistry; Chemical mechanisms; Air quality modeling; Ozone; Acid deposition

Potential impacts of two SO₂ oxidation pathways on regional sulfate concentrations: Aqueous-phase oxidation by NO₂ and gas-phase oxidation by Stabilized Criegee Intermediates by Golam Sarwar; Kathleen Fahey; Roger Kwok; Robert C. Gilliam; Shawn J. Roselle; Rohit Mathur; Jian Xue; Jianzhen Yu; William P.L. Carter (pp. 186-197).

We examine the potential impacts of two additional sulfate production pathways using the Community Multiscale Air Quality modeling system. First we evaluate the impact of the aqueous-phase oxidation of S(IV) by nitrogen dioxide using two published rate constants, differing by 1–2 orders of magnitude. The reaction with alternate high and low rate constants enhances monthly mean wintertime sulfate by 4–20% and 0.4–1.2% respectively. The reaction does not significantly impact summertime sulfate. The higher sulfate predictions in winter compare better with the observed data as the model tends to underpredict sulfate concentrations both in winter and summer. We also investigate the potential impact of the gas-phase oxidation of sulfur dioxide by the Stabilized Criegee Intermediate (SCI) using a recently measured rate constant for its reaction with sulfur dioxide. Model results indicate that the gas-phase oxidation of sulfur dioxide by the SCI does not significantly affect sulfate concentrations due to the competing reaction of the SCI with water vapor. The current estimate of the rate constant for the SCI reaction with water vapor is too high for the SCI reaction with sulfur dioxide to significantly affect sulfate production. However, a sensitivity analysis using a lower rate constant for the water vapor reaction suggests that the SCI reaction with sulfur dioxide could potentially enhance sulfate production in the model. Further study is needed to accurately measure the rate constants of the aqueous-phase oxidation of S(IV) by nitrogen dioxide and the gas-phase reaction of the SCI with water vapor.► Examine the impact of aqueous-phase oxidation of S(IV) by NO₂ on sulfate. ► The aqueous-phase oxidation of S(IV) by NO₂ increases mean winter sulfate by 4–20%. ► The aqueous-phase oxidation of S(IV) by NO₂ does not increase summer sulfate. ► Examine the impact of SO₂ oxidation by Stabilized Criegee Intermediate on sulfate. ► The SO₂ oxidation by Stabilized Criegee Intermediate does not enhance sulfate.

Keywords: Sulfate; Aqueous chemistry; Criegee intermediate; SO; ₂; NO; ₂; Alkene; O; ₃

Computational fluid dynamics modeling of transport and deposition of pesticides in an aircraft cabin by Sastry S. Isukapalli; Sagnik Mazumdar; Pradeep George; Binnian Wei; Byron Jones; Clifford P. Weisel (pp. 198-207).

Spraying of pesticides in aircraft cabins is required by some countries as part of a disinsection process to kill insects that pose a public health threat. However, public health concerns remain regarding exposures of cabin crew and passengers to pesticides in aircraft cabins. While large scale field measurements of pesticide residues and air concentrations in aircraft cabins scenarios are expensive and time consuming, Computational Fluid Dynamics (CFD) models provide an effective alternative for characterizing concentration distributions and exposures. This study involved CFD modeling of a twin-aisle 11 row cabin mockup with heated manikins, mimicking a part of a fully occupied Boeing 767 cabin. The model was applied to study the flow and deposition of pesticides under representative scenarios with different spraying patterns (sideways and overhead) and cabin air exchange rates (low and high). Corresponding spraying experiments were conducted in the cabin mockup, and pesticide deposition samples were collected at the manikin's lap and seat top for a limited set of five seats. The CFD model performed well for scenarios corresponding to high air exchange rates, captured the concentration profiles for middle seats under low air exchange rates, and underestimated the concentrations at window seats under low air exchange rates. Additionally, both the CFD and experimental measurements showed no major variation in deposition characteristics between sideways and overhead spraying. The CFD model can estimate concentration fields and deposition profiles at very high resolutions, which can be used for characterizing the overall variability in air concentrations and surface loadings. Additionally, these model results can also provide a realistic range of surface and air concentrations of pesticides in the cabin that can be used to estimate potential exposures of cabin crew and passengers to these pesticides.► Disinsection of aircraft is required by some countries on international flights. ► Computational Fluid Dynamics model for pesticides in aircraft was developed/evaluated. ► CFD model predicted loading at 29 ACH well, but underestimated some levels at 1 ACH. ► CFD model provided high resolution air and loading estimates for pesticide exposures.

Keywords: CFD; Pesticide; Pyrethroid; Permethrin; Airliner cabin; Disinsection

Chemical constituents in clouds and rainwater in the Puerto Rican rainforest: Potential sources and seasonal drivers by Adriana Gioda; Olga L. Mayol-Bracero; Frederick N. Scatena; Kathleen C. Weathers; Vinicius L. Mateus; William H. McDowell (pp. 208-220).

Cloud- and rain-water samples collected between 1984 and 2007 in the Luquillo Experimental Forest, Puerto Rico, were analyzed in order to understand the main processes and sources that control their chemistry. Three sites were used: El Verde Field Station (380 m asl), Bisley (361 m asl), and East Peak (1051 m asl). Bulk rainwater samples were collected from all sites, and cloud water was also collected on East Peak. All samples were analyzed for pH, conductivity, and concentrations of Cl⁻, SO₄²⁻, NO₃⁻, NH₄⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺. Similar patterns in overall chemistry were observed for both cloud- and rain-water samples. The majority of samples had low acidity (average pH of 4.4–5.0), similar to other remote sites. Sea salt (Na⁺ and Cl⁻) had a large influence on rain and cloud chemistry and accounted for approximately 70% of the total mass of solutes, followed by SO₄⁼, which controls the acidity of the clouds and rainwater. Calcium accounted for 6–8% of the total cations and dominated neutralization processes. The highest concentrations of Ca²⁺ and NO₃⁻ in both cloud- and rain-water were observed in the summertime when large amounts of dust from the African continent reached the sites. Enrichment Factor and Principal Component Analyses showed that Na⁺, Cl⁻, and Mg²⁺ in the cloud- and rain-water were primarily of marine origin, while most of the Ca²⁺ was from crustal sources; and NO₃⁻ was predominantly anthropogenic, presumably from both local and long-range sources. In general, the results of this study suggested that cloud- and rain-water chemistry in northeastern Puerto Rico is strongly influenced by natural and marine sources rather than local anthropogenic sources. The pollutant species in the samples were mainly derived from long distance transport.► Results of a long-term of monitoring of rain and cloud water in background sites. ► Few places on the Planet are possible to collect cloud water with natural features. ► The results are important for comparison and evaluation of anthropogenic impacts. ► Concentrations, trends, seasonality and correlations are discussed in the paper. ► It is important to understand the effects of nutrients and pollutants on ecosystems.

Keywords: Precipitation chemistry; Long-range transport; Saharan dust; Background marine; El Yunque National Forest; Pico del Este

Contamination characteristics and possible sources of PM10 and PM2.5 in different functional areas of Shanghai, China by Jun Wang; Zimei Hu; Yuanyuan Chen; Zhenlou Chen; Shiyuan Xu (pp. 221-229).

From July 2009 through September 2010, PM10 and PM2.5 were collected at two different functional areas in Shanghai (Baoshan district, an industrial area, and Putuo district, a mixed-use area of residential, commercial, and educational compounds). In our analysis, 15 elements were determined using a 710-ES Inductively Coupled Plasma-Emission Spectrometer (ICP-AES). The contents of PM2.5, PM10, and metal elements at the two different sites were comparatively analyzed. The results show that the mean annual concentrations of PM10 and PM2.5 (149.22 μg m⁻³ and 103.07 μg m⁻³, respectively) in Baoshan district were significantly higher than those in Putuo district (97.44 μg m⁻³ and 62.25 μg m⁻³ respectively). The concentrations of PM10 and PM2.5 were both greatest in winter and lowest in summer, with the two different sites exhibiting the same seasonal variation. It was found that the proportions of 15 metal elements in PM10 and PM2.5 in Baoshan district were 20.49% and 20.56%, respectively, while the proportions in Putuo district were higher (25.98% and 25.93%, respectively). In addition, the proportions of eight heavy metals in PM10 and PM2.5 were 5.50% and 3.07%, respectively, for Baoshan district, while these proportions in Putuo district were 3.18% and 2.77%, respectively, indicating that heavy metal pollution is more pronounced in Baoshan district. Compared with cities in developed countries, the total levels of PM10, PM2.5 and heavy metals in Shanghai were slightly higher. Scanning electron microscopy (SEM) and principal component analysis (PCA) suggested that the possible sources of PM10 in Baoshan district were ground level fugitive dust, traffic sources, and industrial activities, whereas PM2.5 mainly originated from industrial activities, coal combustion, and traffic sources. The sources are same for PM10 and PM2.5 in Putuo region, which originate from traffic sources and ground level fugitive dust.► Analyzed the contents of PM2.5, PM10, metal elements at different functional areas. ► Compared the levels of PM10, PM2.5, heavy metals with cities in other countries. ► The total levels of PM and heavy metals were slightly higher than developed countries. ► Identify the possible sources of PM10 and PM2.5 with SEM and PCA. ► Preliminary source apportionment results suggested that PM mainly from local sources.

Keywords: PM10; PM2.5; Heavy metals; Source apportionment; Different functional areas; Shanghai

Contamination characteristics and possible sources of PM10 and PM2.5 in different functional areas of Shanghai, China by Jun Wang; Zimei Hu; Yuanyuan Chen; Zhenlou Chen; Shiyuan Xu (pp. 221-229).

Keywords: PM10; PM2.5; Heavy metals; Source apportionment; Different functional areas; Shanghai

Carbon isotopic characterization of hydrophobic dissolved organic carbon in rainwater by G. Brooks Avery Jr.; K. Farhana Biswas; Ralph Mead; Melissa Southwell; Joan D. Willey; Robert J. Kieber; Katherine M. Mullaugh (pp. 230-234).

The¹⁴C and¹³C content of the hydrophobic fraction (C18 extractable) of dissolved organic carbon (DOC) in Wilmington North Carolina USA rainwater was determined for six rain events to elucidate potential sources. A two end member mass-balance calculation indicated that 42–61% of the hydrophobic DOC was of fossil fuel origin compared to previously published values (4–24%) for bulk rain DOC indicating a strong anthropogenic contribution to the hydrophobic component. All fossil fuel derived organic carbon in the bulk DOC (∼15% fossil fuel derived) could be accounted for in the hydrophobic fraction (∼52% fossil fuel derived) which represents approximately 1/3 of the bulk DOC. The δ¹³C values of the hydrophobic DOC were consistent (−28.8 ± 0.9‰) similar to that for terrestrial and fossil fuel derived organic carbon. This is in contrast to previously published bulk rain DOC δ¹³C values that displayed a strong influence of air-mass back-trajectory with δ¹³C values ranging from −20.8‰ (typical of marine organic carbon) for marine air-mass back-trajectory rain to −28.2‰ (typical of terrestrial or fossil fuel derived organic carbon) for terrestrial air-mass back-trajectory rain. The combination of¹⁴C and¹³C isotopic data strongly suggests that a large fraction of hydrophobic organic material in rain comes from incompletely combusted fossil fuels. Changes in energy usage patterns and efforts to reduce fossil fuel emissions will alter the abundance of this hydrophobic material in the atmosphere which may impact the spectral distribution of sunlight reaching the earth's surface as well as the degree of oceanic primary productivity.

Keywords: Rain; Precipitation; Dissolved organic carbon; Isotopes; ¹³; C; ¹⁴; C; Hydrophobic dissolved organic matter; Solid phase C18 extraction

Atmospheric deposition as a source of heavy metals in urban stormwater by Janaka Gunawardena; Prasanna Egodawatta; Godwin A. Ayoko; Ashantha Goonetilleke (pp. 235-242).

Atmospheric deposition is one of the most important pathways of urban stormwater pollution. Atmospheric deposition, which can be in the form of either wet or dry deposition have distinct characteristics in terms of associated particulate sizes, pollutant types and influential parameters. This paper discusses the outcomes of a comprehensive research study undertaken to identify important traffic characteristics and climate factors such as antecedent dry period and rainfall characteristics which influences the characteristics of wet and dry deposition of solids and heavy metals. The outcomes confirmed that Zinc (Zn) is correlated with traffic volume whereas Lead (Pb), Cadmium (Cd), Nickel (Ni), and Copper (Cu) are correlated with traffic congestion. Consequently, reducing traffic congestion will be more effective than reducing traffic volume for improving air quality particularly in relation to Pb, Cd, Ni, and Cu. Zn was found to have the highest atmospheric deposition rate compared to other heavy metals. Zn in dry deposition is associated with relatively larger particle size fractions (>10 μm), whereas Pb, Cd, Ni and Cu are associated with relatively smaller particle size fractions (<10 μm). The analysis further revealed that bulk (wet plus dry) deposition which is correlated with rainfall depth and contains a relatively higher percentage of smaller particles compared to dry deposition which is correlated with the antecedent dry period. As particles subjected to wet deposition are smaller, they disperse over a larger area from the source of origin compared to particles subjected to dry deposition as buoyancy forces become dominant for smaller particles compared to the influence of gravity. Furthermore, exhaust emission particles were found to be primarily associated with bulk deposition compared to dry deposition particles which mainly originate from vehicle component wear.► Correlated atmospheric pollutant deposition with traffic and climate factors. ► Wet deposition contain high fraction of small particles compared to dry deposition. ► Wet deposition not influenced by proximity to sources of pollutant generation. ► Zn has relatively high dry and wet deposition rates compared to other heavy metals. ► Air quality is influenced more by traffic congestion rather than traffic volume.

Keywords: Air pollutants; Atmospheric deposition; Heavy metals; Stormwater pollution; Traffic emissions

Atmospheric deposition as a source of heavy metals in urban stormwater by Janaka Gunawardena; Prasanna Egodawatta; Godwin A. Ayoko; Ashantha Goonetilleke (pp. 235-242).

Keywords: Air pollutants; Atmospheric deposition; Heavy metals; Stormwater pollution; Traffic emissions

Variability in tropospheric carbon monoxide over an urban site in Southeast Asia by L.K. Sahu; Varun Sheel; M. Kajino; P. Nedelec (pp. 243-255).

This paper analyses MOZAIC (Measurements of Ozone aboard Airbus in-service airCraft) measurements of carbon monoxide (CO) profiles over Bangkok to discuss the seasonality in vertical distribution during year 2005–2006. The mixing ratios of CO were enhanced in the lower troposphere being highest in winter followed by summer and wet seasons. During all the seasons, the mixing ratio of CO decreased rapidly and remained low in the middle troposphere. At higher altitudes (6–12 km), CO shows enhanced values particularly during wet and early winter seasons. The strong seasonality in CO was caused by the seasonal shift in the patterns of the long-range transport and biomass burning (BB) in South and Southeast Asia (S–SE Asia). Flow of cleaner air and negligible BB resulted in the lowest mixing ratio of CO in the wet season. In addition to anthropogenic influence, the long-range transport and BB caused the higher CO in the winter and summer seasons, respectively. Despite extensive local BB activities in Thailand during the summer season, the moderate levels of CO were attributed to the dilution due to flow of cleaner marine from the Indian and Pacific Oceans. We have also compared the observations with the Model for Ozone And Related Chemical Tracers (MOZART) simulations. Mostly the observations lie between the MOZART-2 and MOZART-4 simulations as they underestimate and overestimate the observed CO, respectively. In the middle and upper troposphere, both the observed and simulated mixing ratios of CO during September–November of year 2006 were higher by 15–30 ppbv compared to the same period of year 2005. Our analysis indicates the impact of El Niño induced extensive BB in Indonesia during the year 2006.► Seasonality in tropospheric vertical profile of CO over Bangkok. ► Seasonality in impact of biomass burning in S–SE Asia. ► Comparison of MOZAC vertical CO with MOZART simulations.

Keywords: Bangkok; Southeast Asia; Biomass burning; MOZAIC; Carbon monoxide profile; Urban

Variability in tropospheric carbon monoxide over an urban site in Southeast Asia by L.K. Sahu; Varun Sheel; M. Kajino; P. Nedelec (pp. 243-255).

Keywords: Bangkok; Southeast Asia; Biomass burning; MOZAIC; Carbon monoxide profile; Urban

Assessing exposure risk for dust storm events-associated lung function decrement in asthmatics and implications for control by Nan-Hung Hsieh; Chung-Min Liao (pp. 256-264).

Asian dust storms (ADS) events are seasonally-based meteorological phenomena that exacerbate chronic respiratory diseases. The purpose of this study was to assess human health risk from airborne dust exposure during ADS events in Taiwan. A probabilistic risk assessment framework was developed based on exposure and experimental data to quantify ADS events induced lung function decrement. The study reanalyzed experimental data from aerosol challenge in asthmatic individuals to construct the dose–response relationship between inhaled dust aerosol dose and decreasing percentage of forced expiratory volume in 1 s (%FEV₁). An empirical lung deposition model was used to predict deposition fraction for size specific dust aerosols in pulmonary regions. The toxicokinetic and toxicodynamic models were used to simulate dust aerosols binding kinetics in lung airway in that %FEV₁ change was also predicted. The mask respirators were applied to control the inhaled dose under dust aerosols exposure. Our results found that only 2% probability the mild ADS events were likely to cause %FEV₁ decrement higher than 5%. There were 50% probability of decreasing %FEV₁ exceeding 16.9, 18.9, and 7.1% in north, center, and south Taiwan under severe ADS events, respectively. Our result implicates that the use of activated carbon of mask respirators has the best efficacy for reducing inhaled dust aerosol dose, by which the %FEV₁ decrement can be reduced up to less than 1%.► Aerosol binding kinetic-based toxicodynamic model can predict dust aerosol induced FEV₁ decrement. ► Probabilistic risk framework can assess dust storm events-induced FEV₁ decrement. ► The surgical mask with activated carbon can control dust storm attack effectively.

Keywords: Asian dust storm; Asthma; Lung function; Probabilistic risk assessment; Respiratory protection

Assessing exposure risk for dust storm events-associated lung function decrement in asthmatics and implications for control by Nan-Hung Hsieh; Chung-Min Liao (pp. 256-264).

Keywords: Asian dust storm; Asthma; Lung function; Probabilistic risk assessment; Respiratory protection

Molecular characterization of organic aerosol using nanospray desorption/electrospray ionization mass spectrometry: CalNex 2010 field study by Rachel E. O’Brien; Alexander Laskin; Julia Laskin; Shang Liu; Robin Weber; Lynn M. Russell; Allen H. Goldstein (pp. 265-272).

Aerosol samples from the CalNex 2010 field study were analyzed using high-resolution mass spectrometry (HR-MS) coupled to a nanospray desorption/electrospray ionization (nano-DESI) source. The samples were collected in Bakersfield, CA on June 22-23, 2010. The chemical formulas of over 850 unique molecular species were detected in the mass range of 50–400 m/ z using positive mode ESI of aerosol samples in the 0.18–0.32 μm size range. Our analysis focused on identification of two main groups: compounds containing only carbon, hydrogen, and oxygen (CHO), and nitrogen-containing organic compounds (NOC). The NOC accounted for 40% (by number) of the compounds observed in the afternoon, and for 52% in the early morning samples. By comparing plausible reactant–product pairs, we propose that over 50% of the NOC in each sample could have been formed through reactions transforming carbonyls into imines. The CHO only compounds were dominant in the afternoon suggesting a photochemical source. The average O/C ratios of all observed compounds were fairly consistent throughout the day, ranging from 0.33 in the morning to 0.37 at night. We conclude that both photooxidation and ammonia chemistry may play a role in forming the compounds observed in this mixed urban-rural environment.Display Omitted► We characterize the chemical composition of aerosols collected during CalNex 2010. ► We observe changes in the composition of the oligomeric fraction throughout the day. ► There were increased numbers of nitrogen-containing compounds at night. ► Reactions with ammonia to form imines are possible formation pathways. ► Increased numbers of CHO compounds during the day, likely a result of photochemistry.

Keywords: SOA; Oligomers; Orbitrap; CalNex; Nano-DESI; Nitrogen-containing organic compounds

Density and elemental ratios of secondary organic aerosol: Application of a density prediction method by Shunsuke Nakao; Ping Tang; Xiaochen Tang; Christopher H. Clark; Li Qi; Eric Seo; Akua Asa-Awuku; David Cocker III (pp. 273-277).

Organic material density is a fundamental parameter in aerosol science, yet direct measurement is not readily available. This study investigates density and elemental ratios of secondary organic aerosol (SOA) formed by the oxidation of 22 different volatile organic compounds with a wide range of molecular size (C5∼C15) in an environmental chamber. Reactants with a larger number of carbons yielded SOA with lower density (e.g., β-caryophyllene SOA: 1.22 g cm⁻³) compared with smaller ones (e.g., phenol SOA: 1.43 g cm⁻³) consistent with different extents of oxidation of the parent molecule. A recent study proposed a semi-empirical relationship between elemental ratios (O/C and H/C) and organic material density (Kuwata et al., 2012). The prediction method therein is evaluated against the large experimental data set of this study acquired in the UC Riverside/CE-CERT environmental chamber. The predicted particle densities agree with experimental measurements within 12% as stated by Kuwata et al. (2012) except for C6 compounds (benzene, phenol, and catechol). Therefore, the range of application has been further extended to include anthropogenic (aromatic) systems. The effects of nitrogen and sulfur on the density prediction remain unclear.

Keywords: Secondary organic aerosol; Density; Elemental ratio; Environmental chamber

Respirable Crystalline Silica (RCS) emissions from industrial plants – Results from measurement programmes in Germany by C. Ehrlich; G. Noll; E. Wusterhausen; W.-D. Kalkoff; R. Remus; C. Lehmann (pp. 278-285).

Numerous research articles dealing with Respirable Crystalline Silica (RCS) in occupational health because epidemiological studies reveal an association between RCS-dust and the development of silicosis as well as an increased probability of developing lung cancer. Research activities about RCS in ambient air are known from US-measurements. However there is a lack of knowledge regarding RCS-emissions in several industrial sectors. Industrial sources of crystalline silica include construction, foundries, glass manufacturing, abrasive blasting or any industrial or commercial use of silica sand, and mining and rock crushing operations. This paper describes a RCS-emission measurement method for stack gases and report results from the German RCS-emission measurement programmes which were used to identify installations and types of industries with the highest concentration levels of RCS in stack gases. A two-stage cascade impactor was used for the measurements which separate particles into the following size fractions: >10 μm, 10–4 μm und <4 μm of aerodynamic diameter. The measurements were carried out according to international sampling standards. The size of crystalline silica particles of most concern are those respirable particles that are smaller than four microns (millionths of a metre), also called particulate matter 4 (PM₄). The analytical procedure of determining crystalline silica in emission samples (in the fraction below 4 μm) consists of using x-ray diffraction and infrared spectroscopy methods which are the same methods as used in the field of occupational health. A total of 37 emission measurement campaigns were assessed (112 RCS-samples in nine industrial sectors). The investigated plants are located in different German states such as Bavaria, North Rhine Westphalia, Baden-Wuerttemberg, Rhineland-Palatinate and Saxony-Anhalt. The results of the measurements show that most of the investigated plants can achieve compliance with the newly developed German emission limit value (ELV) of 1 mg m⁻³. The ELV is expressed as the concentration of RCS in stack emissions. According to the German emission minimising principle and the precautionary principle it is assumed that by complying with the RCS-ELV there is no ambient air health risk for people living these plants. In the case of increased total dust concentration in the stack gas (more than 20 mg m⁻³) combined with increased percentage of crystalline silica in PM₄ dust, a violation of the above mentioned ELV is more likely. This applies mostly to installations in the silica sand processing industry. To comply with the ELV of 1 mg m⁻³, efficient emission control technology should be implemented and should be well maintained.► 37 Respirable Crystalline Silica (RCS) emission measurement campaigns. ► Nine industrial sectors were investigated and assessed. ► RCS-emissions of most plants comply with an emission limit value (ELV) of 1 mg m⁻³ RCS. ► Not complying with ELV was observed in some silica sand processing plants.

Keywords: Respirable crystalline silica (RCS); Particulate matter 4 (PM4); Industrial emission measurement programmes; Emission limit value (ELV); Cascade impactor; Silica emission rates; Silica stack test

Developing a predictive tropospheric ozone model for Tabriz by Rahman Khatibi; Leila Naghipour; Mohammad A. Ghorbani; Michael S. Smith; Vahid Karimi; Reza Farhoudi; Hadi Delafrouz; Hadi Arvanaghi (pp. 286-294).

Predictive ozone models are becoming indispensable tools by providing a capability for pollution alerts to serve people who are vulnerable to the risks. We have developed a tropospheric ozone prediction capability for Tabriz, Iran, by using the following five modeling strategies: three regression-type methods: Multiple Linear Regression (MLR), Artificial Neural Networks (ANNs), and Gene Expression Programming (GEP); and two auto-regression-type models: Nonlinear Local Prediction (NLP) to implement chaos theory and Auto-Regressive Integrated Moving Average (ARIMA) models. The regression-type modeling strategies explain the data in terms of: temperature, solar radiation, dew point temperature, and wind speed, by regressing present ozone values to their past values. The ozone time series are available at various time intervals, including hourly intervals, from August 2010 to March 2011. The results for MLR, ANN and GEP models are not overly good but those produced by NLP and ARIMA are promising for the establishing a forecasting capability.► Air pollution is an increasing problem in Tabriz. ► The aim is to develop an ozone (O₃) prediction capability for a city. ► Regression-type models (MLR, ANN and GEP) use meteorological variables. ► Their results are not particularly promising. ► Auto-regression-type models (ARIMA and NLP) performances are promising.

Keywords: Tropospheric ozone; Environmental hazard; Policy; Protecting the public; Prediction capability (MLR, ANN, GEP, ARIMA, chaos theory)

New Directions: Time to tackle urban wood burning? by Gary W. Fuller; Jean Sciare; Martin Lutz; Sophie Moukhtar; Sandra Wagener (pp. 295-296).

Heterogeneous reactions of volatile organic compounds in the atmosphere by Xiaoli Shen; Yue Zhao; Zhongming Chen; Dao Huang (pp. 297-314).

Volatile organic compounds (VOCs) are of central importance in the atmosphere because of their close relation to air quality and climate change. As a significant sink for VOCs, the fate of VOCs via heterogeneous reactions may explain the big gap between field and model studies. These reactions play as yet unclear but potentially crucial role in atmospheric processes. In order to better evaluate this reaction pathway, we present the first specific review for the progress of heterogeneous reaction studies on VOCs, including carbonyl compounds, organic acids, alcohols, and so on. Our review focuses on the processes for heterogeneous reactions of VOCs under varying experimental conditions, as well as their implications for trace gas and HO_x budget, secondary organic aerosol (SOA) formation, physicochemical properties of aerosols, and human health. Finally, we propose the future direction for laboratory studies of heterogeneous chemistry of VOCs that should be carried out under more atmospherically relevant conditions, with a special emphasis on the effects of relative humidity and illumination, the multicomponent reaction systems, and reactivity of aged and authentic particles. In particular, more reliable uptake coefficients, based on the abundant elaborate laboratory studies, appropriate calibration, and logical choice criterion, are urgently required in atmospheric models.► We present the first specific review for studies on heterogeneous reactions of VOCs. ► Implications for trace gases, SOA formation and aerosol properties are suggested. ► Heterogeneous processes may explain VOCs big gap between field and model studies. ► We propose the future laboratory studies of heterogeneous chemistry of VOCs. ► More reliable uptake coefficients are urgently required in atmospheric models.

Keywords: Heterogeneous reaction; Volatile organic compounds; Uptake coefficient; HO; _x; budget; SOA formation; Aerosol ageing

Heterogeneous reactions of volatile organic compounds in the atmosphere by Xiaoli Shen; Yue Zhao; Zhongming Chen; Dao Huang (pp. 297-314).

Keywords: Heterogeneous reaction; Volatile organic compounds; Uptake coefficient; HO; _x; budget; SOA formation; Aerosol ageing

Domestic versus international contributions on 2050 ozone air quality: How much is convertible by regional control? by Hang Lei; Donald J. Wuebbles; Xin-Zhong Liang; Seth Olsen (pp. 315-325).

A global climate chemistry model CAM-Chem is driven by the meteorology output from community climate system model version 3 (CCSM3) to investigate the relative contributions of changes in local anthropogenic emissions (LE) versus changes in remote anthropogenic emissions (RE) to global surface ozone air quality in 2050. On major ozone pollution regions (Europe, the United States, Asia), the effects are examined following three distinct pathways, A1FI, A1B and B1, from the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) to address the uncertainty in projections of future climate and emissions. We find that projected changes in anthropogenic emissions under the A1FI scenario lead to an increase of 5–14 ppb in summertime daily maximum 8-h (DM8H) ozone concentration over U.S. by 2050, of which 48% is contributed by LE changes and 52% is contributed by RE changes. For Europe, the change in local emissions contributes 62% of the surface ozone increase in 2050 summer, while 38% of the increase is attributed to remote emission change. For Asia, changes in LE dominate the 2050 surface ozone increase with a magnitude of 10–30 ppb on summertime DM8H ozone concentration. However, under the A1B and B1 scenarios, contributions from LE changes are much larger than that from RE changes over all three regions except Asia under the B1 scenario, in which the RE changes contribute 31% of total change. The results indicate that for the United States and Europe, pollution control is a local issue under global low emission situations, while it becomes an international issue when fossil fuel use is rapidly increasing. Due to the weak Euro-Asia transport, local emission increase seems to be the main force for Asia's ozone air quality change under all cases except the low emission scenario B1. Therefore, the strategies for regional air quality control need to be based on global emission situation.► Effectiveness of regional air quality control strategy depends on global emissions. ► Asian ozone air quality change is more affected by changes in domestic emissions. ► Domestic emissions more affect U.S. and Europe under low emission scenarios. ► But international emissions may be important under high emission scenarios. ► Air quality change somehow can become an international issue as global warming.

Keywords: Air quality; Ozone; Climate change; Anthropogenic emission; Uncertainty

Domestic versus international contributions on 2050 ozone air quality: How much is convertible by regional control? by Hang Lei; Donald J. Wuebbles; Xin-Zhong Liang; Seth Olsen (pp. 315-325).

Keywords: Air quality; Ozone; Climate change; Anthropogenic emission; Uncertainty

Characterization of atmospheric organic matter using size-exclusion chromatography with inline organic carbon detection by Youliang Wang; Chao-An Chiu; Paul Westerhoff; Kalliat T. Valsaraj; Pierre Herckes (pp. 326-332).

The atmosphere contains a substantial amount of water-soluble organic material in aerosols, clouds and fogs. Despite years of efforts, little is known on the structure, composition and properties of this organic matter with most studies focusing on individual species while the bulk of the organic matter remains poorly characterized.In this work high-performance size-exclusion chromatography coupled with inline organic carbon detection (SEC-DOC) is used to characterize organic matter in fogs, clouds and aerosols collected in Fresno (CA), Whistler (BC), Davis (CA) and Selinsgrove (PA). The molecular weight distributions showed a fractional overlap of atmospheric samples and terrestrial fulvic acids although for clouds and aerosols the smaller molecular weight (MW) material is dominant. This smaller MW material is clearly resolved. Cloud and fog samples showed a larger fraction of small molecular weight organic species compared to the water-soluble fraction of aerosols, consistent with the partitioning of small molecular weight volatile species into the atmospheric aqueous phase. There are overall little differences between different sites for a same type of sample. These results obtained by one analytical set-up were confirmed with a second size-exclusion chromatography set-up using a different column and detection system. Size distributions for the same sampling location showed little inter-event variability and water-soluble organic carbon (WSOC) samples were slightly shifted toward larger sizes compared to clouds and fogs, consistent with an important contribution of volatile species to the latter ones. Cloud and aerosol samples contributed to a significant fraction (up to 21% of dissolved organic carbon (DOC)) of the macromolecular scale material.► Size-exclusion chromatography with inline carbon detection was applied to atmospheric samples. ► A substantial fraction of atmospheric organic matter is macromolecular. ► There is little difference in molecular weight distributions between different events at a particular site. ► There are small differences in molecular weight distributions between sites. ► The results were confirmed with a second independent size-exclusion organic matter detection set-up.

Keywords: Cloud chemistry; Fog chemistry; WSOC; HULIS; Dissolved organic matter

Levels and potential sources of atmospheric organochlorine pesticides at Korea background sites by Guang-Zhu Jin; Sang-Min Kim; Su-Yeong Lee; Jin-Soo Park; Dong-Hoon Kim; Min-Jin Lee; Ki-Tae Sim; Hak-Gu Kang; Il-Gyu Kim; Sun-Kyoung Shin; Kwang-Seol Seok; Seung-Ryul Hwang (pp. 333-342).

Data are presented for 11 organochlorine pesticides (OCPs) measured by high volume air samplers at three background sites (monthly for one site, seasonally for two sites) in South Korea during June 2008 and December 2009, and levels, seasonal variations and potential sources of high levels of OCPs and impact of long-range transport (LRT) were discussed. Geometric mean (GM) concentrations of OCPs in air samples (pg m⁻³) were highest for HCB (80, 15.0–256), HCH (71, 10.8–547), a currently used pesticide, DDT (3.50, ND-56.5), and Chlordane (1.15, ND-10.5). Other chemicals regularly detected included, Heptachlor (0.41, ND-2.59), Drins (0.61, ND-4.36) and Mirex (0.04, ND-0.78). Seasonal variation of OCPs was featured by higher concentrations in summer and lower in winter period. This could be associated with their temperature-driven re-volatilization from historical source and recent application of some OCPs (such as dicofol, HCH etc). Ratios of specific OCPs isomers suggest that dominant source of air HCHs in Korea background sites is technical HCH with a little input of lindane in recent time, and dominant source of air DDT is old and used technical DDT with a little bit of dicofol type DDT, and current air chlordane in Korean background sites mainly come from the source of historically used chlordane. The results from this study will provide comparable and scientifically sound data of OCP in background air and will contribute to further long-term POPs monitoring program in East Asia.► Atmospheric OCPs in three Korea background sites were investigated. ► Elevated levels of HCB, HCHs, DDT and Chlordane were found. ► It suggests the combined influence of emissions from local reservoirs and LRT. ► Atmospheric OCPs were featured by higher levels in summer and lower in winter.

Keywords: OCPs; Air; Background sites; South Korea

Ozone phytotoxicity evaluation and prediction of crops production in tropical regions by Nurul Izma Mohammed; Nor Azam Ramli; Ahmad Shukri Yahya (pp. 343-349).

Increasing ozone concentration in the atmosphere can threaten food security due to its effects on crop production. Since the 1980s, ozone has been believed to be the most damaging air pollutant to crops. In Malaysia, there is no index to indicate the reduction of crops due to the exposure of ozone. Therefore, this study aimed to identify the accumulated exposure over a threshold of X ppb (AOTX) indexes in assessing crop reduction in Malaysia. In European countries, crop response to ozone exposure is mostly expressed as AOT40. This study was designed to evaluate and predict crop reduction in tropical regions and in particular, the Malaysian climate, by adopting the AOT40 index method and modifying it based on Malaysian air quality and crop data. Nine AOTX indexes (AOT0, AOT5, AOT10, AOT15, AOT20, AOT25, AOT30, AOT40, and AOT50) were analyzed, crop responses tested and reduction in crops predicted. The results showed that the AOT50 resulted in the highest reduction in crops and the highest R² value between the AOT50 and the crops reduction from the linear regression analysis. Hence, this study suggests that the AOT50 index is the most suitable index to estimate the potential ozone impact on crops in tropical regions. The result showed that the critical level for AOT50 index if the estimated crop reduction is 5% was 1336 ppb h. Additionally, the results indicated that the AOT40 index in Malaysia gave a minimum percentage of 6% crop reduction; as contrasted with the European guideline of 5% (due to differences in the climate e.g., average amount of sunshine).► Predicted crop reduction in Malaysia by adopting the AOT40 index method. ► Nine AOTX indexes were analyzed, crop responses tested and its reduction predicted. ► The AOT50 index gave the highest R² value between the AOT50 and the crops reduction. ► The critical level for AOT50 index if the crop reduction is 5% was 1336 ppb h. ► The AOT40 index in Malaysia gave a minimum percentage of 6% crop reduction.

Keywords: AOT40; AOT50; AOTX indexes; Oryza sativa

Ozone phytotoxicity evaluation and prediction of crops production in tropical regions by Nurul Izma Mohammed; Nor Azam Ramli; Ahmad Shukri Yahya (pp. 343-349).

Keywords: AOT40; AOT50; AOTX indexes; Oryza sativa

Corrigendum to “Do cosmic-ray-driven electron-induced reactions impact stratospheric ozone depletion and global climate change?” [Atmos. Environ. 45 (2011), 3408–3514] by Jens-Uwe Grooß; Rolf Müller (pp. 350-350).

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