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Atmospheric Environment (v.39, #30)

Editorial board (pp. i).

List for forthcoming papers (pp. i-ii).

Sampling artifacts in measurement of elemental and organic carbon: Low-volume sampling in indoor and outdoor environments by David A. Olson; Gary A. Norris (pp. 5437-5445).

Experiments were completed to determine the extent of artifacts from sampling elemental carbon (EC) and organic carbon (OC) under sample conditions consistent with personal sampling. Two different types of experiments were completed; the first examined possible artifacts from oils used in personal environmental monitor (PEM) impactor plates, and the second examined artifacts from microenvironmental sampling using different sampling media combinations (quartz, Teflon, XAD denuder, and electrostatic precipitator). The effectiveness of front and backup filters was evaluated for most sampling configurations. Mean total carbon concentrations from sampling configurations using impactor oils were not statistically different from the control case (using a sharp cut cyclone). Three microenvironments were tested (kitchen, library, and ambient); carbon concentrations were highest in the kitchen using a front quartz filter (mean OC of 16.4μgm⁻³). The lowest front quartz filter concentrations were measured in the library using XAD denuders (mean OC of 3.6μgm⁻³). Denuder removal efficiencies (average of 82% for total carbon) were lower compared with previous ambient studies and may indicate that indoor sources influenced denuder efficiency during sample collection. The highest carbon concentrations from backup quartz filters were measured using the Teflon–quartz combination.

Keywords: Organic carbon; Elemental carbon; Sampling artifact; Personal exposure

An electronic pollen detection method using Coulter counting principle by Zheng Zhang; Jiang Zhe; Santanu Chandra; Jun Hu (pp. 5446-5453).

A method for detecting and counting pollen particles based on Coulter counting principle is presented. This approach also provides information on the size and surface charges of the micro particles, allowing for preliminary differentiation of pollens from other micro particles. Three samples are studied: polymethyl methacrylate particles, tree pollens from Juniperus Scopulorum and grass pollens from Secale Cerale. The samples, suspended in diluted KCl aqueous solutions in an electrochemical cell, were allowed to pass through a microchannel and the conductance of the microchannel was sampled with a Gamry^� Potentiostat. The changes in the conductance due to the passing of the micro particles was thus recorded and analyzed. The experimental results showed that tree pollens and grass pollens display distinctive behaviors. The phenomena may be attributed to the differences in the surface characteristics of the pollens and is potentially useful for counting and differentiating different micro particles.

Keywords: Micro particle; Pollen analysis; Coulter counter; Biosensor; Electronic nose

Aerodynamic characteristics and respiratory deposition of fungal fragments by S.-H. Seung-Hyun Cho; S.-C. Sung-Chul Seo; Detlef Schmechel; Sergey A. Grinshpun; Tiina Reponen (pp. 5454-5465).

The purpose of this study was to investigate the aerodynamic characteristics of fungal fragments and to estimate their respiratory deposition. Fragments and spores of three different fungal species ( Aspergillus versicolor, Penicillium melinii, and Stachybotrys chartarum) were aerosolized by the fungal spore source strength tester (FSSST). An electrical low-pressure impactor (ELPI) measured the size distribution in real-time and collected the aerosolized fungal particles simultaneously onto 12 impactor stages in the size range of 0.3–10μm utilizing water-soluble ZEF-X10 coating of the impaction stages to prevent spore bounce. For S. chartarum, the average concentration of released fungal fragments was 380particlescm⁻³, which was about 514 times higher than that of spores. A. versicolor was found to release comparable amount of spores and fragments. Microscopic analysis confirmed that S. chartarum and A. versicolor did not show any significant spore bounce, whereas the size distribution of P. melinii fragments was masked by spore bounce. Respiratory deposition was calculated using a computer-based model, LUDEP 2.07, for an adult male and a 3-month-old infant utilizing the database on the concentration and size distribution of S. chartarum and A. versicolor aerosols measured by the ELPI. Total deposition fractions for fragments and spores were 27–46% and 84–95%, respectively, showing slightly higher values in an infant than in an adult. For S. chartarum, fragments demonstrated 230–250 fold higher respiratory deposition than spores, while the number of deposited fragments and spores of A. versicolor were comparable. It was revealed that the deposition ratio (the number of deposited fragments divided by that of deposited spores) in the lower airways for an infant was 4–5 times higher than that for an adult. As fungal fragments have been shown to contain mycotoxins and antigens, further exposure assessment should include the measurement of fungal fragments for evaluating mold exposures in damp buildings.

Keywords: Fragment; Spore; Mold; Exposure; Electrical low-pressure impactor

Study the relationship between the health effects and characterization of thermal inversions in the Sultanate of Oman by Sabah A. Abdul-Wahab; Charles S. Bakheit; R.A. Siddiqui (pp. 5466-5471).

This study was to investigate relationships between the thermal inversion layer and health effects that are associated with air pollution. Records of emergency visits, covering a period of one year, to Oman's Royal Hospital, due to acute respiratory diseases, were used for the study. Cases of four types of diseases, which are linked with atmospheric air pollution, were considered. Emphasis was also placed on the temperature profile data to study the characteristics of inversions. Surface-based inversions occurred almost every day of the year while cases of elevated inversions were more during the summer than during the winter months. For both types of inversions, the depths of most of the inversions did not exceed 200m. Stronger inversions tended to occur with large inversion depths. There were significant associations between the two types of inversions and the incidence of the diseases, measured by the number of emergency hospital visits. The daily average number of hospital visits increased with increasing inversion depth and strength of surface-based inversions. In the case of elevated inversions, the summer months with a high frequency of occurrence had higher figures than the winter months, increasing significantly with the depth but not with the strength of inversion.

Keywords: Surface-based inversion layer; Elevated thermal layer; Diseases; Sultanate of Oman

Organic aggregate formation in aerosols and its impact on the physicochemical properties of atmospheric particles by Azadeh Tabazadeh (pp. 5472-5480).

Fatty acid salts and “humic�? materials, found in abundance in atmospheric particles, are both anionic surfactants. Such materials are known to form organic aggregates or colloids in solution at very low aqueous concentrations. In a marine aerosol, micelle aggregates can form at a low fatty acid salt molality of ∼10⁻³m. In other types of atmospheric particles, such as biomass burning, biogenic, soil dust, and urban aerosols, “humic-like�? materials exist in sufficient quantities to form micelle-like aggregates in solution. I show micelle formation limits the ability of surface-active organics in aerosols to reduce the surface tension of an atmospheric particle beyond about 10dynecm⁻¹. A general phase diagram is presented for anionic surfactants to explain how surface-active organics can change the water uptake properties of atmospheric aerosols. Briefly such molecules can enhance and reduce water uptake by atmospheric aerosols at dry and humid conditions, respectively. This finding is consistent with a number of unexplained field and laboratory observations. Dry electron microscope images of atmospheric particles often indicate that organics may coat the surface of particles in the atmosphere. The surfactant phase diagram is used to trace the particle path back to ambient conditions in order to determine whether such coatings can exist on wet ambient aerosols. Finally, I qualitatively highlight how organic aggregate formation in aerosols may change the optical properties and chemical reactivity of atmospheric particles.

Keywords: Organic aerosol; Micelle; Organic coats; Water uptake; Surface tension

Locally induced surface air confluence by complex terrain and its effects on air pollution in the valley of Mexico by Aron D. Jazcilevich; Agust�n R. Garc�a; Ernesto Caetano (pp. 5481-5489).

Using a meteorological computational model it is shown how, in the Valley of Mexico, a high pressure system together with the complex orography of the region induce the formation of a local confluence line. With the aid of a prognostic air quality model it is shown that the maximum pollutant mixing ratios are placed on and follow the confluence line which crosses over the most populated areas of Mexico City. This phenomenon provides an explanation of why and when pollutants assume its geographical distribution in the valley during high mixing ratio episodes.

Keywords: Mexico City; Air pollution modeling; Air quality; Air flow in complex terrain

Compositional fractionation of polycyclic aromatic hydrocarbons (PAHs) in mosses ( Hypnum plumaeformae WILS.) from the northern slope of Nanling Mountains, South China by Xiang Liu; Gan Zhang; Kevin C Jones; Xiangdong Li; Xianzhi Peng; Shihua Qi (pp. 5490-5499).

High mountains may serve both as condenser for vapor phase persistent organic pollutants (POPs) and as barrier/sink for particulate associated less volatile POPs. The fractionation of POPs along altitudinal profiles is of interest in understanding the role of high mountains in the atmospheric transport of POPs. In the present study, polycyclic aromatic hydrocarbons (PAHs) in a selected moss species , Hypnum plumaeformae WILS, from two altitudinal profiles on the northern slope of Nanling mountains in Southern China were analyzed and compared with those in air samples. The total PAH concentration in the mosses was 310–1340ngg⁻¹ dry weight, with phenanthrene being the most abundant. The distribution patterns of PAHs in the moss samples matched well with those in bulk atmosphere deposition in the adjacent source areas. The PAH distribution pattern in the mosses was a composite of both particle-associated and vapor phase PAHs, with heavy PAHs are susceptible to uptake/retention by mosses than light PAHs. A plot of log ( C_moss/ C_air) against log K_oa gave a good linear relationship in the log K_ao range of 6.7–10.2. It is suggested that the widely spread moss, H. plumaeformae WILS, can be used as an effective tool in the biomonitoring of atmospheric PAHs pollution in East Asia. The concentrations of most PAHs in the mosses generally declined with increasing altitude. In addition, there was a shift in compound pattern with an increase in the proportion of light PAHs (2–3 rings), a decrease in heavy PAHs (5–6 rings) and a relatively stable content of 4-ring PAHs. A combination of particulate scavenging and cold condensation are proposed as the major mechanisms for the compositional fractionation of PAHs along the altitudinal profile.

Keywords: Moss; High mountains; Polycyclic aromatic hydrocarbons (PAHs); Monitoring; Atmospheric deposition; Fractionation; Long-range transport; Southern China

Women's personal and indoor exposures to PM_2.5 in Mysore, India: Impact of domestic fuel usage by Penny Rechkemmer Andresen; Gurumurthy Ramachandran; Pramod Pai; Andrew Maynard (pp. 5500-5508).

In traditional societies, women are more likely to be adversely affected by exposures to fine particulates from domestic fuel combustion due to their role in the family as the primary cooks. In this study, 24-h gravimetric personal and indoor PM_2.5 exposures were measured for 15 women using kerosene and another 15 women using liquefied petroleum gas (LPG) as their main cooking fuel in Mysore, India. The women also answered a detailed questionnaire regarding their residential housing characteristics, health status, cooking practices and socioeconomic status. Repeated measurements were obtained during two seasons.The main objective of this study was to determine whether exposures to PM_2.5 differed according to fuel usage patterns. A repeated-measures general linear model (GLM) was used to analyze the data. Women using kerosene as their primary cooking fuel had significantly higher exposures. During summer, the arithmetic mean (± standard error) for kerosene users personal exposure was 111±13 and 71±15μgm⁻³ for LPG users. Kerosene users had higher exposures in winter (177±21μgm⁻³) compared to summer exposures. However, for LPG users there was no difference in their seasonal geometric mean exposures at 71±13μgm⁻³. Indoor concentrations followed similar patterns. In summer, kerosene-using households had an arithmetic mean concentration of 98±9μgm⁻³ and LPG-using households had an arithmetic mean concentration of 71±9μgm⁻³. Winter concentrations were significantly higher than summer concentrations for kerosene users (155±13μgm⁻³). Again, LPG users showed only slightly higher indoor concentrations (73±6μgm⁻³) than kerosene users. Socioeconomic status, age, season and income were significant predictors of cooking fuel choice.

Keywords: Women's exposures; Domestic fuel combustion; Indoor air pollution; Exposure assessment; Cooking fuels; PM; _2.5

Effects of liquid VOC concentration and salt content on partitioning equilibrium of hydrophilic VOC at air–sweat interface by Wen-Hsi Cheng; Fu-Sui Chu; Tzy-I Su (pp. 5509-5516).

Volatile organic compounds (VOCs) must initially be absorbed by sweat on the surface of skin for human VOC dermal exposure. The partitioning equilibrium at the air–sweat interface is given bypc=Cg*/CL, where p_c is the partitioning coefficient, andCg* is the gaseous concentration in equilibrium with the aqueous VOC concentration ( C_L) at a constant water temperature ( T_w). A series of thermodynamic functions ofCg*(CL,TW) are presented, as well as the values of p_c, and the heat of gaseous–liquid phase transfer (Δ H_tr) for tested VOCs, including iso-propanol (IPA, C_L=12–120mgL⁻¹) and methyl ethyl ketone (MEK, C_L=10–80mgL⁻¹) to determine the effects of liquid VOC concentration and salt contents of sweat on p_c of hydrophilic VOCs. Experimental data reveal that the p_c values of IPA and MEK drop as the liquid VOC concentrations increasing from 10 to 120mgL⁻¹. However, sodium salt content in human sweat (sodium chloride and sodium lactate) induces the effect of salt, indicating the increase in p_c. Notably, neither urea nor ammonia in human sweat increase p_c. Artificial sweat, consisting of sodium chloride 0.47%, urea 0.05%, ammonia 0.004% and sodium lactate 0.6%, was used to evaluate the increase in the p_c values of IPA and MEK. The liquid VOC concentration effect simultaneously develops together with the salt effect on the partition at the interface of air–sweat for hydrophilic VOC solutions. The p_c values of IPA for artificial sweat decrease as much as 32.5% as C_L increases from 12 to 120mgL⁻¹ at 300K, and those of MEK drop by as much as 70.9% as C_L increases from 10 to 80mgL⁻¹ at 300K. This investigation provides a basis for elucidating the assessment of human dermal exposure to hydrophilic VOCs.

Keywords: Henry's law; Volatile organic compound (VOC); Concentration effect; Salt effect; Sweat; Dermal; Exposure

Source contribution to aromatic VOC concentration and ozone formation potential in the atmosphere of Seoul by Kwangsam Na; K.-C. Kil-Choo Moon; Yong Pyo Kim (pp. 5517-5524).

This study reports the seasonal trend of C₆–C₉ aromatic volatile organic compounds (VOCs) and estimates the contribution of vehicle exhaust and evaporative emissions to the total aromatic VOC concentration and ozone formation potential in the atmosphere of Seoul, Korea. Measurements of aromatic VOCs were made at a site in Seoul for 21 months from 1997 to 1999. Twenty-four-hour integrated canister samples of aromatic VOCs were collected over the course of the study and a GC/MS system was used for their quantification. Aromatic VOCs showed a weak seasonal variation, with higher concentrations during the winter and lower concentrations during the summer. This was due to higher evaporative emissions in the summer and lower evaporative emissions in the winter. Factor analysis results showed that aromatic VOC concentrations came from vehicle exhaust and evaporative emissions. A simple approximation was proposed to estimate the relative contribution of vehicle exhaust and evaporative emissions. The calculation result indicates that on an average, 58% of the total aromatic VOC concentration originated from vehicle exhaust. However, during the summer, evaporative emissions were a larger contributor to the aromatic VOC concentrations in the atmosphere relative to vehicle exhaust by a factor of 1.3. It was determined by means of a scatter plot that an increase in temperature led to an increase in evaporative emissions. Further, the ozone formation potentials for these two major emission sources of ambient aromatic VOCs were evaluated in terms of maximum incremental reactivity. Evaporative emissions were found to have 40% higher ozone-forming potential than vehicle exhaust in the summer. Xylene was the largest contributor to the ozone formation. Benzene had the lowest ozone formation potential.

Keywords: Aromatic VOCs; Source contribution; Vehicle exhaust; Evaporative emissions; Seasonal variation; Ozone-forming potential

Deposition of particles to a thin windbreak: The effect of a gap by John D. Wilson (pp. 5525-5531).

It is shown that the ‘bleed velocity’ through the ‘fabric’ of a thin windbreak or shelterbelt is practically insensitive to the existence of nearby holes or gaps in the fabric. This provides the basis for a straightforward extension of an earlier formula for particle ‘scrubbing’ by a thin windbreak, to account for irregularities of the filtering vegetation or mesh.

Keywords: Wind; Shelter; Windbreak; Particulates; Aerosols; Filtering; Deposition

Methane and carbon dioxide fluxes from a shallow hypereutrophic subtropical Lake in China by Yangping Xing; Ping Xie; Hong Yang; Leyi Ni; Yuesi Wang; Kewen Rong (pp. 5532-5540).

Up to now, there have been few studies in the annual fluxes of greenhouse gases in lakes of subtropical regions. The fluxes of methane (CH₄) and carbon dioxide (CO₂) across air–water interface were measured in a shallow, hypereutrophic, subtropical Lake Donghu (China) over a year cycle, using a static chamber technique. During the year, Lake Donghu emitted CH₄ and CO_2; the average flux of CH₄ and CO₂ was 23.3 ±18.6 and 332.3±160.1mgm⁻²d⁻¹, respectively. The fluxes of CH₄ and CO₂ showed strong seasonal dynamics: CH₄ emission rate was highest in summer, remaining low in other seasons, whereas CO₂ was adsorbed from the atmosphere in spring and summer, but exhibited a large emission in winter. Annual carbon (C) budget across air–water interface in Lake Donghu was estimated to be 7.52±4.07×10⁸g. CH₄ emission was correlated positively with net primary production (NPP) and temperature, whereas CO₂ flux correlated negatively with NPP and temperature; however, there were no significant relationships between the fluxes of CH₄ and CO₂ and dissolved organic carbon, a significant difference from boreal lakes, indicating that phytoplankton rather than allochthonous matter regulated C dynamics across air–water interface of subtropical lake enriched nutrient content.

Keywords: Methane emission; Carbon dioxide flux; NPP; Temperature; Subtropical lake

Long-term characterization of ionic species in aerosols from urban and high-altitude sites in western India: Role of mineral dust and anthropogenic sources by N. Rastogi; M.M. Sarin (pp. 5541-5554).

Concentrations of water-soluble-ionic-species (NH₄⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, NO₃⁻, SO₄²⁻ and HCO₃⁻) in the ambient aerosols and their temporal variability have been studied for a 3-year period (2000–2002) from an urban site (Ahmedabad, 23.0°N, 72.6°E, 49m asl) and a high-altitude station (Mt Abu, 24.6°N, 72.7°E, 1680m asl) located in a semi-arid region of western India. During the drier months (January–April, September–December), the average concentrations (μgm⁻³) of water-soluble species in the aerosols over Ahmedabad are: HCO₃⁻: 4.95, SO₄²⁻: 4.57, Ca²⁺: 2.96, NO₃⁻: 2.07, Cl⁻: 0.99, Na⁺: 0.81, K⁺: 0.76, NH₄⁺: 0.48, Mg²⁺: 0.25. During the wet period of the SW-monsoon (May–August), the contribution of Na⁺ (2.42μgm⁻³) and Cl⁻ (3.96μgm⁻³) are significantly enhanced. In spite of the geographic and altitude differences, the composition of aerosols from the two sites shows comparable ratios among the major species (Ca²⁺, HCO₃⁻ and SO₄²⁻). On average, during dry period, nss-SO₄²⁻/nss-Ca²⁺ and HCO₃⁻/nss-Ca²⁺ ratios over Ahmedabad are 1.6 and 1.7; and those over Mt Abu are 1.9 and 2.0, respectively. During wet phase, the corresponding ratios are 1.3 and 1.7 over Ahmedabad and 1.2 and 1.8 over Mt Abu. Although the concentrations of several species are significantly different over the two sites and exhibit large seasonal variations, their inter-annual variability is nowhere pronounced. Unlike the chemical characteristics reported over other urban regions, aerosols sampled in this study are of alkaline nature with major neutralizing component as Ca²⁺ rather than NH₄⁺. As a result, significant uptake of acidic species (NO₃⁻ and SO₄²⁻ derived from pollution sources) by mineral aerosols (CaCO₃) is a dominant chemical transformation process over the study sites.

Keywords: Aerosol chemical composition; Water-soluble ions; Sea salts; Acidic components; Mineral aerosols

Atmospheric visibility trends in an urban area in Taiwan 1961–2003 by Ying I. Tsai (pp. 5555-5567).

Climatological observations made in Tainan urban area, southern Taiwan, between 1961 and June 2003 were analyzed along with critical air pollutants monitored from 1994 to June 2003 in order to establish the relationship between atmospheric visibility and major air pollutants and meteorological parameters in the urban area. The visibility discrepancy between weekend and week days was also examined. Average annual visibility in the complete period 1961–2003 was 12.4±4.2km. However, during the early 1960s it was >20km, against only 6–7km between 2002 and 2003. This study revealed a correlation between PM₁₀ and NO _x levels, which were higher on weekdays than on weekends, and low weekday visibility. Furthermore, decreased visibility was related mostly to increases in PM₁₀. A weekend effect, in which weekend ozone concentrations exceed weekday concentrations, was also revealed. Mixing layer height is an most important meteorological parameter involved in visibility reduction. Principal component analysis demonstrated that increased vehicular emissions, road traffic dust and industrial activity markedly impacted visibility. Pollutant standard index (PSI) values >100 were characterized by concentrations of PM₁₀ and NO _x and atmospheric pressure higher than normal, but with wind speed lower than normal. Regression results for various empirical models of visibility demonstrated that higher PM₁₀ concentrations implied lower visibility ranges, and the parameter of ln[PM₁₀] represented the most significant impact on visibility. Because PM_2.5 has a significant impact on visibility, a targeted reduction of PM₁₀ would not completely improve the visual range. However, there is a strong association between presence of PM₁₀ and presence of PM_2.5, such that a targeted reduction in PM₁₀ is likely to lead to an increase in visibility.

Keywords: Visibility reduction; Mixing layer height; Weekend effect; Principal component analysis

Source and evolution of the “perfect Asian dust storm�? in early April 2001: Implications of the Sr–Nd isotope ratios by Takanori Nakano; Masataka Nishikawa; Ikuko Mori; Kicheol Shin; Takahiro Hosono; Yoriko Yokoo (pp. 5568-5575).

The “perfect Asian dust storm,�? so-called from the huge, clear picture obtained of it by earth-orbiting satellites, occurred over a vast area of northern China and Mongolia and moved eastward across the northern Pacific in early April 2001. We determined the Sr–Nd isotopic ratios of acid-resistant minerals and the Sr isotopic ratios of weak-acid-soluble minerals in the dust from this storm deposited at nine sites from northern China to Japan and compared these data with those ratios of surface arid soils in northern China. The isotopic compositions of the dust minerals resembled those from soils of the Badain Juran, Tengger, and Ulan Buh deserts and the area to their north, which on meteorological grounds are considered to be the emission area of the dust plume, but they varied regionally, reflecting the heterogeneity of the source soils. Our results and those of other meteorological and modeling studies suggest that this variation was caused by mixing with local soils uplifted into the lower part of the dust plume, but further downwind the dust was less mixed with local soils and was derived mainly from the upper dust plume. Mineral isotope, mineralogical, and elemental data on Asian dusts and soils in northern China and Mongolia provide invaluable information on physical and chemical processes of dust storms and on dust source areas.

Keywords: Asian dust; Perfect dust storm; Sr–Nd isotopes; Dust source; Soil-mixing

Numerical modelling of flow over stockpiles: Implications on dust emissions by T. Badr; J.L. Harion (pp. 5576-5584).

This paper considers fugitive dust emissions from open aggregate storage piles on industrial sites. The process of wind erosion depends strongly on the local wind flow characteristics and is considerably affected by flow field changes caused by any modifications in terrain geometry. Prediction of wind flow over stockpiles plays a dominant role in the assessment of potential erosion and the evaluation of its environmental impact. Three-dimensional numerical simulations, based on solution of the Reynolds Averaged Navier–Stokes equations and thek-ω shear stress transport turbulence model, were performed to describe the flow over two typical pile geometries with different wind directions. The surface roughness effect was also accounted for in the simulations. Results are then validated against wind tunnel derived experimental data from an Environmental Protection Agency (EPA) study. The simulations presented in this study successfully predict flow patterns over the stockpiles. Further development of these simulations will allow testing of more realistic site configurations, including various pile geometries and complex terrain as well as different flow conditions.

Keywords: Fugitive dust emissions; Wind erosion; Stockpiles; Computational fluid dynamics (CFD)

Estimation of the input data for the prediction of road transportation emissions in Spain from 2000 to 2010 considering several scenarios by J.M. Buron Jos� M. Bur�n; Francisco Aparicio; O. �scar Izquierdo; A. �lvaro G�mez; Lopez Ignacio L�pez (pp. 5585-5596).

This paper presents a study of pollutant emissions by road vehicles in Spain for the period 2000–2010. This study forms part of the SETISMO project, a global study of transportation in Spain for 1988–2010, and represents the logical continuation of the analysis of pollutant emissions by road transportation in Spain for 1988–1999. The study is based on the use of COPERT III software, of wide acceptance in Europe.The study for 1988–1999 emissions focused on obtaining input data for COPERT. The lack of data as well as the aggregated form of the available data were the main difficulties of the process, and required the design of a specific methodology for the Spanish case in that particular period. The period 2000–2010 was based upon two scenarios defined in terms of macroeconomical variables: GNP, population and infrastructure investment. These were used, through an economical model, to predict mobility for the period. The vehicle emission forecast was calculated upon that basis, considering future regulations, expectable technological evolution and other variables.The main results of the study are the emission series for a wide collection of pollutants, although the research process and the methodology followed led to secondary results of equal statistical value in terms of precision and degree of deaggregation (determined by the COPERT III Methodology categorization of vehicles). These scenario-based series constitute an illuminating forecast of road transportation pollutant emissions in Spain, allowing to predict the effect of future pollutant emission regulations as well as to identify the necessity for CO₂ emission–reduction policies in order to comply with Kyoto protocol levels.

Keywords: Atmospheric pollutant; Mobility; Number of vehicles; Emission; Fleet; Traffic; Spain

A simple semi-empirical photochemical model for the simulation of ozone concentration in the Seoul metropolitan area in Korea by C.-H. Cheol-Hee Kim; S.-U. Soon-Ung Park; C.-K. Chang-Keun Song (pp. 5597-5607).

O₃ concentrations were simulated over the Seoul metropolitan area in Korea using a simple semi-empirical reaction (SEGRS) model which consists of generic reaction set (GRS), photochemical reaction set, and the diagnostic wind field generation model. The aggregated VOC emission strength was empirically scaled by the comparison of the simulated slope of (O₃–2NO–NO₂) concentration as a function of cumulative actinic light flux against measurements on high surface ozone concentration days with the relatively weak easterly geostrophic winds at the 850hPa level in summer when the effect of horizontal advection was fairly small. The results indicated that the spatial distribution patterns and temporal variations of spatially averaged ground-level ozone concentrations were quite well simulated compared with those of observations with the modified volatile organic compound (VOC) emission strength. The diurnal trend of the surface ozone concentration and the maximum concentration compared observations were also quite reasonably simulated. However, the maximum ozone concentration occurring time at Seoul lagged about 2h and the ozone concentration in the suburban area was slightly overestimated in the afternoon due to the influx of high ozone concentration from the urban area. It was found that the SEGRS model could be effectively used to simulate or predict the ground-level ozone concentration reasonably well without heavy computational cost provided the emission of ozone precursors are given.

Keywords: Semi-empirical photochemical model; Ozone concentration simulation; Seoul metropolitan area; Generic reaction set

A study of historical surface ozone measurements (1884–1900) on the island of Gozo in the central Mediterranean by Michael Nolle; Raymond Ellul; Frank Ventura; Hans G�sten (pp. 5608-5618).

Historical surface ozone measurements (1884–1900) made using the Schönbein method on the rural island of Gozo (Malta) were used as proxy data for the climatological evaluation of the relative seasonal changes of the ozone concentration in preindustrial times.In combination with historical meteorological measurements (temperature, relative humidity, wind speed and direction) on Gozo, a new approach to humidity correction of the historical Schönbein measurements is presented using boundary-layer considerations of the old and modern measuring site near by. The humidity-corrected Schönbein measurements from Gozo indicate—contrary to present day's ozone concentrations on Gozo—a clear annual ozone minimum in the summer. The spring maximum of the annual ozone variation in the northern hemisphere observed worldwide is also evident from the corrected Schönbein data from Gozo.An attempt to reconstruct the absolute values of the monthly averages of the ozone-mixing ratios on Gozo in the 19th century reveals that the average ozone-mixing ratios in the central Mediterranean could have increased by a factor of five since that time. However, a critical discussion of the shortcomings of the Schönbein method suggests that the quantitative conclusions drawn from the historical ozone measurements in question must be interpreted with care.

Keywords: Surface ozone; Central Mediterranean; Island of Gozo (Malta); Historical Sch�nbein method; Humidity correction

Relations among stability parameters in the stable surface layer: Golder curves revisited by Maithili Sharan; T.V.B.P.S. Rama Krishna; Jagabandhu Panda (pp. 5619-5623).

A nomogram was prepared by [Golder, 1972. Boundary Layer Meteorology 3, 47–58] to compute the surface layer parameters in stable conditions. This note revisits the Golder's curves and examines the methodology underlying their derivation in stable conditions. The inherent limitation in the methodology used for construction of Golder's curves was also noticed by Trombetti et al. (1986). Surface layer fluxes computed using the parameters derived from modified curves are found to be closer to the turbulence measurements from CASES-99 experiment for stable conditions than those calculated from the [Golder, 1972. Boundary Layer Meteorology 3, 47–58] curves.

Keywords: Nomogram; Bulk Richardson number; Surface layer; Golder's curves

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Atmospheric Environment (v.39, #30)