Atmospheric Environment (v.91, #C)
Editorial board (i).
Emission inventories for ships in the arctic based on satellite sampled AIS data by Morten Winther; Jesper H. Christensen; Marlene S. Plejdrup; Erik S. Ravn; Ómar F. Eriksson; Hans Otto Kristensen (1-14).
This paper presents a detailed BC, NO x and SO2 emission inventory for ships in the Arctic in 2012 based on satellite AIS data, ship engine power functions and technology stratified emission factors. Emission projections are presented for the years 2020, 2030 and 2050. Furthermore, the BC, SO2 and O3 concentrations and the deposition of BC are calculated for 2012 and for two arctic shipping scenarios – with or without arctic diversion routes due to a possible polar sea ice extent in the future.In 2012, the largest shares of Arctic ships emissions are calculated for fishing ships (45% for BC, 38% for NO x , 23% for SO2) followed by passenger ships (20%, 17%, 25%), tankers (9%, 13%, 15%), general cargo (8%, 11%, 12%) and container ships (5%, 7%, 8%). In 2050, without arctic diversion routes, the total emissions of BC, NO x and SO2 are expected to change by +16%, −32% and −63%, respectively, compared to 2012. The results for fishing ships are the least certain, caused by a less precise engine power – sailing speed relation.The calculated BC, SO2, and O3 surface concentrations and BC deposition contributions from ships are low as a mean for the whole Arctic in 2012, but locally BC additional contributions reach up to 20% around Iceland, and high additional contributions (100–300%) are calculated in some sea areas for SO2. In 2050, the arctic diversion routes highly influence the calculated surface concentrations and the deposition of BC in the Arctic. During summertime navigation contributions become very visible for BC (>80%) and SO2 (>1000%) along the arctic diversion routes, while the O3 (>10%) and BC deposition (>5%) additional contributions, respectively, get highest over the ocean east of Greenland and in the High Arctic.The geospatial ship type specific emission results presented in this paper have increased the accuracy of the emission inventories for ships in the Arctic. The methodology can be used to estimate shipping emissions in other regions of the world, and hence may serve as an input for other researchers and policy makers working in this field.
Keywords: AIS; Arctic; Ship emissions; BC; NO x ; SO2; Surface concentration; Deposition;
Spatio-temporal modelling of residential exposure to particulate matter and gaseous pollutants for the Heinz Nixdorf Recall Cohort by Michael Nonnemacher; Hermann Jakobs; Anja Viehmann; Irene Vanberg; Christoph Kessler; Susanne Moebus; Stefan Möhlenkamp; Raimund Erbel; Barbara Hoffmann; Michael Memmesheimer (15-23).
For the simultaneous analysis of short- and long-term effects of air pollution in the Heinz Nixdorf Recall Cohort a sophisticated exposure modelling was performed. The dispersion and chemistry transport model EURAD (European Air Pollution Dispersion) was used for the estimation of hourly concentrations of a number of pollutants for a horizontal grid with a cell size of 1 km² covering the whole study area (three large adjacent cities in a highly urbanized region in Western Germany) for the years 2000–2003 and 2006–2008. For each 1 km² cell we estimated the mean concentration by calculating daily means from the hourly concentrations modelled by the EURAD process. The modelled concentrations showed an overall tendency to decrease from 2001 to 2008 whereas the trend in the single grid cells and study period was inhomogeneous. Participant-related exposure slightly increased from 2001 to 2003 followed by a decrease from 2006 to 2008. The exposure modelling enables a very flexible exposure assessment compared to conventional modelling approaches which either use central monitoring or temporally static spatial contrasts. The modelling allows the calculation of an average exposure concentration for any place and time within the study region and study period with a high spatial and temporal resolution. This is important for the assessment of short-, medium and long-term effects of air pollution on human health in epidemiological studies.
Keywords: Heinz Nixdorf Recall Study; EURAD model; Spatio-temporal exposure modelling; Long-term exposure; Short-term exposure;
Mortality reduction following the air pollution control measures during the 2010 Asian Games by Hualiang Lin; Yonghui Zhang; Tao Liu; Jianpeng Xiao; Yanjun Xu; Xiaojun Xu; Zhenmin Qian; Shilu Tong; Yuan Luo; Weilin Zeng; Wenjun Ma (24-31).
Though increased particulate air pollution has been consistently associated with elevated mortality, evidence regarding whether diminished particulate air pollution would lead to mortality reduction is limited. Citywide air pollution mitigation program during the 2010 Asian Games in Guangzhou, China, provided such an opportunity. Daily mortality from non-accidental, cardiovascular and respiratory diseases was compared for 51 intervention days (November 1–December 21) in 2010 with the same calendar date of baseline years (2006–2009 and 2011). Relative risk (RR) and 95% confidence interval (95% CI) were estimated using a time series Poisson model, adjusting for day of week, public holidays, daily mean temperature and relative humidity. Daily PM10 (particle with aerodynamic diameter less than 10 μm) decreased from 88.64 μg/m3 during the baseline period to 80.61 μg/m3 during the Asian Games period. Other measured air pollutants and weather variables did not differ substantially. Daily mortality from non-accidental, cardiovascular and respiratory diseases decreased from 32, 11 and 6 during the baseline period to 25, 8 and 5 during the Games period, the corresponding RR for the Games period compared with the baseline period was 0.79 (95% CI: 0.73–0.86), 0.77 (95% CI: 0.66–0.89) and 0.68 (95% CI: 0.57–0.80), respectively. No significant decreases were observed in other months of 2010 in Guangzhou and intervention period in two control cities. This finding supports the efforts to reduce air pollution and improve public health through transportation restriction and industrial emission control.
Keywords: Particulate air pollution; Mortality; Intervention; Asian games;
Degradation kinetics of levoglucosan initiated by hydroxyl radical under different environmental conditions by Chengyue Lai; Yongchun Liu; Jinzhu Ma; Qingxin Ma; Hong He (32-39).
To understand the atmospheric stability of levoglucosan, which is a major molecular tracer used for source apportionment of biomass burning aerosols, degradation kinetics of levoglucosan by hydroxyl radical (OH) have been investigated using a flow reactor under different conditions. The second-order rate constant (k 2) for the degradation of pure levoglucosan by OH is (9.17 ± 1.16) × 10−12 cm3 molecules−1 s−1 at 25 °C and 40% relative humidity (RH), while it depends on environmental conditions such as temperature, RH, and mixing state. At 25 °C, k 2 of pure levoglucosan linearly decreases with increasing RH (k 2 = (1.50 ± 0.04) × 10−11 − (1.31 ± 0.11) × 10−11 RH), while it increases with increasing temperature and follows the Arrhenius equation k 2 = (6.2 ± 5.6) × 10−9exp[(–1922.5 ± 268.2)/T] when the RH is 40%. At 25 °C and 40% RH, compared to pure levoglucosan, levoglucosan coated on (NH4)2SO4 or NaCl (levoglucosan@(NH4)2SO4 and levoglucosan@NaCl) shows larger k 2 to OH with (9.53 ± 0.39) × 10−12 and (10.3 ± 0.45) × 10−12 cm3 molecules−1 s−1, respectively, whereas levoglucosan coated on soot (levoglucosan@soot) shows the smaller k 2 of (4.04 ± 0.29) × 10−12 cm3 molecules−1 s−1. Either (NH4)2SO4 or NaCl internally mixed with levoglucosan ((NH4)2SO4@levoglucosan and NaCl@levoglucosan) prominently inhibits the degradation of levoglucosan. Based on the rate constants, atmospheric lifetimes of levoglucosan were estimated to be 1.2–3.9 days under different conditions. All the results indicate that the degradation of levoglucosan by OH is prominent during air mass aging, and it should have an important influence on the uncertainty of source apportionment if the contribution of degradation to levoglucosan concentration is not considered in source apportionment models.
Keywords: Levoglucosan; Hydroxyl radical; Degradation kinetics; Environmental condition; Mixing state;
A modeling study of source–receptor relationships in atmospheric particulate matter over Northeast Asia by Jie Li; Wenyi Yang; Zifa Wang; Huansheng Chen; Bo Hu; Jianjun Li; Yele Sun; Yong Huang (40-51).
The source–receptor relationships (S–R relationships) of PM10 in Northeast Asia were investigated by a three-dimensional regional chemical transport model with emission and meteorological fields in 2010. A model comparison with ground-based measurements, and satellite and lidar remote sensing data showed that the model reproduced well the spatial and temporal distribution of PM10 over Northeast Asia, with correlation coefficients ranging from 0.50 to 0.94 and normalized mean errors (NMEs) of 10–70% at eleven stations. An on-line tracer-tagged module incorporated into the model indicated that self-contribution contributed the greatest percentage of surface PM10 in China, the Korean peninsula and Japan, reaching 48.5%, 41.8% and 39.1%, respectively. The long-range transport from China and offshore along the Asian continent (Bohai bay, China East Sea, China Huang Sea, the Sea of Japan etc.) constituted the second and third major contributing sources in Korea and Japan (13–26%). The naturally produced dust aerosols also contributed significant percentages, averaging 46.5%, 11.7% and 11.0% in China, the Korean peninsula and Japan, respectively. These S–R relationships of PM10 showed high seasonal variability over Northeast Asia. Significant transport was found between city clusters in China, presenting a major challenge to policy makers since most current remediation efforts are confined within one city cluster.
Keywords: Source–receptor relationships; Trans-boundary transport; PM10; Northeast Asia;
Correlations between absorption Angström exponent (AAE) of wintertime ambient urban aerosol and its physical and chemical properties by N. Utry; T. Ajtai; Á. Filep; M. Pintér; Zs. Török; Z. Bozóki; G. Szabó (52-59).
Based on a two-week measurement campaign in an environment heavily polluted both by transit traffic and household heating in the inner city of Szeged (Hungary), correlations between the absorption Angström exponent (AAE) fitted to the optical absorption coefficients measured with a four wavelength (1064, 532, 355 and 266 nm) photoacoustic aerosol measuring system (4λ-PAS) and various aerosol parameters were identified. AAE was found to depend linearly on OCwb/EC and on NGM100/NGMD20, i.e. on the ratio of mass concentrations of elemental carbon (EC) to the fraction of organic carbon associated with wood burning (OCwb), and on the ratio of aerosol number concentrations in the 20 nm (NGMD20) to 100 nm (NGMD100) modes, with a regression coefficient of R = 0.95 and R = 0.86, respectively. In the daily fluctuation of AAE two minima were identified, which coincide with the morning and afternoon rush hours, during which NGMD20 exhibits maximum values. During the campaign the shape of the aerosol volume size distribution (dV/dlogD) was found to be largely invariant, supporting the assumption that the primary driver for the AAE variation was aerosol chemical composition rather than particle size. Furthermore, when wavelength segregated AAE values were calculated, AAE for the shorter wavelengths (AAE355-266) was also found to depend linearly on the above mentioned ratios with similar regression coefficients but with a much steeper correlation line, while the AAE for the longer wavelengths (AAE1064-532) exhibits only a considerably weaker correlation. These results prove the unique advantages of real time multi-wavelength photoacoustic measurement of optical absorption in case the wavelength range includes the ultra-violet too.
Keywords: Aerosol; Absorption; Photoacoustic spectroscopy; Angström exponent; Wood burning; Levoglucosan;
An integrated process rate analysis of a regional fine particulate matter episode over Yangtze River Delta in 2010 by L. Li; C. Huang; H.Y. Huang; Y.J. Wang; R.S. Yan; G.F. Zhang; M. Zhou; S.R. Lou; S.K. Tao; H.L. Wang; L.P. Qiao; C.H. Chen; D.G. Streets; J.S. Fu (60-70).
A high PM2.5 pollution episode was detected in Shanghai in November 2010. The integrated process rate method, an advanced diagnostic tool, was applied to account for the contribution of different atmospheric processes during the high pollution episode in the Yangtze River Delta region (YRD). The PM2.5 process analysis indicates that the emission of fine particles is the dominant source of high surface PM2.5 concentrations in the major cities of the YRD like Shanghai, Nanjing, and Hangzhou, following horizontal transportation and aerosols. The PM2.5 concentration could be reduced due to vertical advection and diffusion from lower levels to the upper air. The aerosols process such as homogeneous nucleation and condensation producing PM2.5 occurs throughout the PBL layer in urban areas, causing vertical transport from upper levels down to the surface layer. The aerosols process is much more significant in a downwind rural and coastal site like Zhoushan than in the urban areas. The PM2.5 change initiated by both horizontal transport and vertical transport is much stronger at 40–2000 m height than in the surface layer, while the PM2.5 change caused by horizontal diffusion is very small. Dry deposition can significantly reduce concentration of the particulates in the surface level of the atmosphere, and wet deposition can remove the particles in the planetary boundary layer (PBL). The cloud processes can either increase PM2.5 due to the aqueous-phase oxidation of SO2 and NO2 or remove PM2.5 due to cloud scavenging. Solar radiation and humidity are more important to secondary pollution, and they are the significant external factors affecting the chemical reactions among sulfur dioxide, nitrogen oxides, ammonia, volatile compounds and fine particles.
Keywords: Integrated process rate; PM2.5; CMAQ; Yangtze River Delta;
Ensemble forecasting with machine learning algorithms for ozone, nitrogen dioxide and PM10 on the Prev'Air platform by E. Debry; V. Mallet (71-84).
This paper presents the application of an ensemble forecasting approach to the Prev’Air operational platform. This platform aims at forecasting maps, on a daily basis, for ozone, nitrogen dioxide and particulate matter. It relies on several air quality models which differ by their physical parameterizations, their input data and numerical strategies, so that one model may perform better with respect to observations for a given pollutant, at a given time and location. We apply sequential aggregation methods to this ensemble of models, which has already proved good potential in previous research papers. Compared to these studies, the novelties of this paper are the variety of models, the real operational context, which requires robustness assessment, and the application to several pollutants. In this paper, we first introduce the ensemble forecasting methods and the operational platform Prev’Air along with its models. Then, the sequential aggregation performance and robustness are assessed using two different data sets.The results with the discounted ridge regression method show that the errors of the forecasts are respectively reduced by at least 29%, 35% and 19% for hourly, daily and peak O3 concentrations, by 19%, 26% and 20% for hourly, daily and peak NO2 concentrations, and finally by 17%, 19% and 11% for hourly, daily and peak PM10 concentrations. At last, we give a first insight of the ensemble ability to forecast threshold exceedances.
Keywords: Operational forecasting; Ensemble forecast; Sequential aggregation; Chemical transport models; Ozone; Nitrogen dioxide; Particulate matter; Threshold exceedance;
Chemical characteristics and source apportionment of PM10 during Asian dust storm and non-dust storm days in Beijing by Qingyang Liu; Yanju Liu; Jianxin Yin; Meigen Zhang; Tingting Zhang (85-94).
To study the chemical characteristics of Asian dust storm, airborne particulate matter PM10 (particles with aerodynamic diameter smaller than 10 μm) was collected at two sites in Beijing from March to May 2012. Water soluble ions, metals, organic carbon and elemental carbon were analyzed. Two dust storm (DS) samples were also collected during the sampling period on March 28th (DS1) and April 28th (DS2). Backward trajectory results showed that both events were originated from Inner Mongolia and Mongolia. A receptor model, positive matrix factorization (PMF) was applied to calculate the soil emission differences between DS and non-DS days. Five emission sources were identified that contribute to PM10, including soil dust, vehicular emission, industrial emission, metal processing and secondary ions. The PMF estimated contributions of dust aerosols to PM10 were in the range of 31%–40% during DS days, which were far greater than that contribution (10%–20%) from local soil dust only during non-DS days. Furthermore, lead isotopic composition analyses in PM10 in Beijing and the soil samples from Inner Mongolia Plateau and Zhangbei Plateau were conducted. Higher lead isotopic ratios (206Pb/207Pb, 206Pb/208Pb) in PM10 were observed in DS days than non-DS days, and those ratio compositions were found to be similar to those observed in the dry lakebed soil samples collected from Inner Mongolia Plateau and Zhangbei Plateau, which indicate that the dry lakebed region served as a dust transport pathway of those two DS events.
Keywords: Chemical characteristics; Dust storm; PM10; Source apportionment; Lead isotope; PMF model;
Evaluation of aviation NO x -induced radiative forcings for 2005 and 2050 by Arezoo Khodayari; Seth C. Olsen; Donald J. Wuebbles (95-103).
Aviation NO x emissions lead to the production of ozone (O3) and an OH increase in the troposphere and lower stratosphere. This OH increase results in a reduction of methane (CH4) which causes a longer-term reduction in O3 concentrations and lower stratospheric water vapor (SWV). Here we report new evaluations of a more comprehensive suite of aviation NO x -induced steady-state radiative forcing (RF) for 2006 aviation NO x emissions and for two different projections of 2050 NO x emissions and compare them with previously published analyses of aviation NO x -induced steady-state RFs. To do so, we evaluate the aviation NO x -induced steady-state RFs using the three-dimensional (3-D) global climate-chemistry Community Atmosphere Model (CAM), CAM4Chem. Moreover, we determine time dependent (transient) RFs for 2005 and the two 2050 emission scenarios by utilizing a parameterization based on specific RFs (steady-state RFs per unit of NO x emission) calculated in the 3-D model simulations, time-dependent NO x emissions data, and considering the lifetime of the perturbed species. For aviation NO x-induced effects we find that the net transient RFs differ from the linearly scaled steady-state RFs (specific steady-state RFs multiplied by NO x emissions) by +10%–36% for the different emission scenarios used in this study. These results indicate the importance of not using the transient and steady-state RF interchangeably, especially when comparing the aviation contribution in RF changes to contributions from other transportation sectors. Also, these results indicate that careful consideration is necessary when choosing whether to use the steady-state or transient RF when evaluating aviation NO x -induced RFs.
Keywords: Aviation; NO x emissions; Simple climate models;
Reactivity of hydrohaloethers with OH radicals and chlorine atoms: Correlation with molecular properties by Pablo R. Dalmasso; Raúl A. Taccone; Jorge D. Nieto; Pablo M. Cometto; Carlos J. Cobos; Silvia I. Lane (104-109).
The reactivity of halogenated ethers, especially hydrochloroethers, with hydroxyl radicals and chlorine atoms was studied by correlating the room-temperature rate coefficients with both the C–H bond dissociation energies and the vertical ionization potentials of the parent molecules. These molecular properties were estimated at the composite G3B3 level of theory. The results suggest that Cl-substituted ethyl-methyl-ethers and ethyl-ethyl-ethers at the β-position tend to raise the activating effect of the ether linkage –O– and to enhance the possibility of the abstraction of H atoms bonded to α-carbon. Derived relationships between the rate coefficients (in cm3 molecule−1 s−1) and ionization potentials (in eV): log k OH = −(1.248 ± 0.065) IP + (1.06 ± 0.73) and log k Cl = −(1.46 ± 0.12) IP + (4.5 ± 1.3) allows, in average, to estimate rate coefficients within a factor of 2–3. The atmospheric implications of halogenated and hydrogenated ethers are briefly discussed on the basis of their estimated global lifetimes.
Keywords: Hydrochloroethers; Gas-phase rate coefficients; Bond dissociation energies; Ionization potentials; Structure–reactivity correlation; Tropospheric chemistry;
Vertical distribution of CO2 in the atmospheric boundary layer: Characteristics and impact of meteorological variables by Yanli Li; Junjun Deng; Chao Mu; Zhenyu Xing; Ke Du (110-117).
Knowledge of vertical CO2 distribution is important for development of CO2 transport models and calibration/validation of satellite-borne measurements. In this study, vertical profiles of CO2 concentration within 0–1000 m were measured using a tethered balloon at a suburban site in Xiamen, which is undergoing fast urbanization. The characteristics of CO2 vertical distribution were investigated under both stable and convective boundary-layer conditions. The correlation of ground level CO2 concentrations and those at high altitudes decreased with altitude and show significant correlation in the first 300 m with R = 0.78 at 100 m, R = 0.52 at 200 m, R = 0.40 at 300 m (P < 0.01). The correlation keeps almost constant for 300–800 m, and there is no obvious correlation at 800 m, indicating that the impact of ground level CO2 was restricted within the 300 m above the ground. When comparing the vertical profiles obtained at different times during a 24 h period, it was found that CO2 concentration exhibited more obvious diurnal pattern at surface level than at high altitude because of the variation of sources and sinks of CO2 at ground level. Most profiles demonstrated declining trends of CO2 concentration with increasing altitude. The vertical profiles of CO2 were fitted to obtain an empirical equation for estimating CO2 vertical concentration in the lower atmosphere (0–1000 m): y = −75.04 + 1.17 × 109e−x/28.01, R 2 = 0.59 (P < 0.05). However, for some cases opposite patterns were observed that the CO2 concentration profiles showed a turning point at a certain altitude or little variation with altitude under certain meteorological conditions. The atmospheric boundary layer depth and atmospheric stability are two major factors controlling the vertical structure of CO2 profile. The results would improve our understanding of the spatial and temporal variation of CO2 in urban environment, which would facilitate using 3-D transport model to study the impacts of CO2 on urban environment.
Keywords: Tethered balloon; CO2; Vertical distribution; Meteorological variables; Boundary layer;
Seasonal ambient ammonia and ammonium concentrations in a pilot IMPROVE NHx monitoring network in the western United States by Xi Chen; Derek Day; Bret Schichtel; William Malm; Ashleigh K. Matzoll; Jose Mojica; Charles E. McDade; Eva D. Hardison; David L. Hardison; Steven Walters; Mark Van De Water; Jeffrey L. Collett (118-126).
Ammonia and ammonium are important atmospheric trace constituents that affect particulate matter concentrations and contribute to reactive nitrogen deposition. We refer to and measure the sum of ammonia and ammonium as NHx. To better understand concentrations of NHx in remote areas, the Interagency Monitoring of Protected Visual Environments (IMPROVE) fine particulate matter (<2.5 μm) sampler was modified to measure NHx at a subset of locations in the routine IMPROVE network. To sample NHx, an additional IMPROVE PM2.5 sampler was installed. Samples were collected on phosphorous acid impregnated cellulose filters held in polypropylene filter holders. While the standard IMPROVE filter holder is made of Delrin (polyoxymethylene, POM), reactions between collected NHx and formaldehyde released by phosphorous acid degradation of the POM holder produced substantial amounts of artifact methylamine, especially during warm sampling periods. This artifact did not occur with the new polypropylene holder design, and no methylamine was measured above the method detection limit of 0.003 μg/m3. Samples collected using the new IMPROVE NHx sampling system were evaluated against samples collected with a collocated URG annular denuder/filter-pack module for 6 weeks; the observed bias was −7%. The NHx monitors were deployed at a total of nine sites in the U.S. Rocky Mountain and Great Plains regions and to the east, and at Bondville, Illinois, from April 2011 to August 2012. Collocated samplers at Rocky Mountain National Park, Colorado, and Bondville, Illinois, demonstrated excellent measurement precision. The data revealed a pattern of increasing NHx concentrations in late spring/early summer (June) and a decrease in winter, starting in September for most of the sites. This pattern is consistent with expected seasonal patterns in agricultural emissions of ammonia. Sites closer to agricultural sources at Bondville and Cedar Bluff (Kansas), however, still exhibit quite abundant winter NHx, which may reflect continued local agricultural emissions trapped within a shallower winter boundary layer. A probable impact of wildfires on NHx concentrations was observed for Bandelier NM, Chiricahua NM, and Yellowstone NP during summer/fall 2011.
Keywords: Ammonia; Ammonium; NHx; IMPROVE; Methylamine;
Analytical approach to estimating aerosol extinction and visibility from satellite observations by Kwon Ho Lee; Man Sing Wong; Kyungwon Kim; Seung Shik Park (127-136).
This study investigates the application of satellite data to the evaluation of aerosol extinction and visibility, for a better understanding of the spatio-temporal variation of local air quality in urban areas. A new analytical model based on aerosol microphysics and non-linear exponential fitting was applied to the analysis of aerosol extinction using aerosol optical thickness (AOT, τ a ) data retrieved from the MODerate-resolution Imaging Spectroradiometer (MODIS), over one of the largest global megacities: Seoul, Korea. The relationship between the MODIS τ a and ground-based aerosol measurements of particulate matter mass concentration, extinction, and surface visibility was assessed over Seoul, Korea, during eight intensive observation periods in 2007–2009. The results clearly demonstrate that satellite-derived τ a is a good surrogate for monitoring aerosol extinction and visibility over this study area. In particular, it is found that MODIS-estimated visibility values have a closer relation to the observed values than traditionally assumed Koschemeider's relation. The analytical results shown in this study can provide a better understanding of aerosol extinction and visibility in megacity, as well as for routine visibility monitoring.
Keywords: Aerosol; Extinction; Visibility; Satellite; Analytical model;
Long-range transport of gaseous 131I and other radionuclides from Fukushima accident to Southern Poland by Jerzy W. Mietelski; Renata Kierepko; Kamil Brudecki; Paweł Janowski; Krzysztof Kleszcz; Ewa Tomankiewicz (137-145).
A serious accident at Fukushima Dai-Ichi NPP triggered radioactive emission to the atmosphere on 12 March 2011. The results of gamma spectrometric measurements of both gaseous and aerosol fraction of the air, collected in Krakow over the period from March 21 till the end of May 2011, as well as wet and dry deposition recorded from March till the end of October 2011, are presented in this paper. Krakow happened to be the first Polish location where radioactive isotopes characteristic for reactor releases, such as 131I, 132I, 129mTe, 132Te, 134Cs, 136Cs, and 137Cs, were detected. The maximum activity for aerosols equal to (5.73 ± 0.35) mBq/m3, (0.461 ± 0.041) mBq/m3 and (0.436 ± 0.038) mBq/m3 for 131I, 134Cs and 137Cs, respectively, was recorded for March 29, 2011. The data on the fallout are also given. The results of the radiochemical analysis of aerosol samples showed no traces of plutonium or americium isotopes associated with the disaster to be detected. The results of air activity concentration from Fukushima accident observed in Central Europe, Poland, in comparison to those of Chernobyl accident observed in Japan are presented and discussed. The comparison has revealed a discrepancy in the recognized relative scale of both accidents, and important difference in long distance transport of contamination, to exist. An attempt to explain the variation in the activity ratios between the aerosol fraction for 131I and 137Cs as resulting from exchange between the gaseous and aerosol fractions of 131I while the contamination had been propagating, is made.
Keywords: Atmospheric radionuclides; Fukushima accident; Radiocesium; Chernobyl; Plutonium; Radioactive fallout;
Improved estimation of PM2.5 using Lagrangian satellite-measured aerosol optical depth by Rolando O. Saunders; Jonathan D.W. Kahl; Jugal K. Ghorai (146-153).
Accurate estimates of fine suspended particulate matter (PM2.5) concentrations are important in air quality and epidemiological studies. Aerosol optical depth (AOD) retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument has been used as an empirical predictor to estimate ground-level concentrations of PM2.5. However, these estimates usually have large uncertainties. The main objective of this work is to assess the value of upwind (Lagrangian) MODIS-AOD as predictors in empirical models of ground-level PM2.5. We also explored the reconstruction of missing MODIS data and developed a daily average uniformly-gridded AOD product. The empirical models developed in this work were tested in ten different sites across the continental United States. Multiple linear regression models that included Lagrangian AOD along in situ AOD as predictors showed statistically significant improvement over the simple linear regression models (PM2.5 and in situ AOD). A set of seasonal categorical variables was included in the regressions to account for the variability of regression performance with respect to seasons. The extended multiple linear regression models exhibited statistically significant improvement over the simple and multiple linear regression models that only contained AOD as predictors.
Keywords: MODIS; Aerosol optical depth (AOD); Air pollution; Remote sensing; Trajectory model;
Standardization methods for testing photo-catalytic air remediation materials: Problems and solution by S. Ifang; M. Gallus; S. Liedtke; R. Kurtenbach; P. Wiesen; J. Kleffmann (154-161).
In the present study, problems of different methods used for quantifying the air remediation activity of photo-catalytic active surfaces are described. It is demonstrated that in bed photo-reactors (e.g. ISO), transport limitations can lead to underestimation of the activity, if fast heterogeneous reactions are investigated. In contrast, in stirred tank photo-reactors (e.g. UNI), complex secondary chemistry may lead to an overestimation of the photo-catalytic remediation of NO x , if NO2 is also present. In addition, the quantities, used for ranking the photo-catalytic air remediation activity in the different methods are not independent of the applied experimental conditions, and thus, make any intercomparison between the different methods or the extrapolation to atmospheric conditions very difficult. Furthermore, unrealistic high NO x levels are used, for which the chemical kinetics may already be affected by surface saturation problems. Finally, it is shown that the use of only nitrogen monoxide (NO) will not enable users to judge about the quality and effectiveness of a photo-catalytic surface for improving air quality, since surfaces which are active toward NO may be completely non-reactive toward other important atmospheric pollutants. A modified method for quantifying the air remediation activity of photo-catalytic surfaces is proposed here to overcome these problems.Display Omitted
Keywords: Photo-catalysis; TiO2; Nitrogen oxides; Air quality; Standardization;
Variations in school playground and classroom atmospheric particulate chemistry by Teresa Moreno; Ioar Rivas; Laura Bouso; Mar Viana; Tim Jones; Mar Àlvarez-Pedrerol; Andrés Alastuey; Jordi Sunyer; Xavier Querol (162-171).
The chemical analysis of 553 school playground and classroom PM2.5 filters collected during the BREATHE sampling campaign in Barcelona, Spain, reveals a remarkable degree of spatial and temporal variability in ambient PM composition. Classroom air quality shows average PM2.5 concentrations of 37 μg m−3 (28% higher than outdoors), with much of this mass comprising carbon (including abundant cotton fibres), blackboard chalk particles and silicates. Where sandy playgrounds are present these exert a major influence on inhalable PM2.5 concentrations both indoors and outdoors. Throughout the city there is widespread contamination by metalliferous traffic particles, especially at schools located close to major urban highways where outdoor EC levels can be an order of magnitude higher than in peripheral, green belt schools. Penetration into the classroom of outdoor EC, ammonium sulphate and anthropogenic metals such as Cu, Sn, Sb, Zn and V is pervasive, especially during warmer months. In contrast, levels of nitrate and ammonium are much higher outdoors than in the classroom, especially during winter. During their work and play, schoolchildren across the city respire in a diversity of chemically differing atmospheric microenvironments.
Keywords: PM2.5 chemistry; Traffic metal PM; Indoor textile fibres; Exposure; Indoor/outdoor;
New Directions: Cleaning the air: Will the European Commission's clean air policy package of December 2013 deliver? by Roy M. Harrison; Bert Brunekreef; Menno Keuken; Hugo Denier van der Gon; Xavier Querol (172-174).
New Directions: Questions surrounding suspended particle mass used as a surrogate for air quality and for regulatory control of ambient urban air pollution by John L. Hoare (175-177).
The original choice of particulate matter mass (PM) as a realistic surrogate for gross air pollution has gradually evolved into routine use nowadays of epidemiologically-based estimates of the monetary and other benefits expected from regulating urban air quality. Unfortunately, the statistical associations facilitating such calculations usually are based on single indices of air pollution whereas the health effects themselves are more broadly based causally. For this and other reasons the economic benefits of control tend to be exaggerated. Primarily because of their assumed inherently inferior respirability, particles ≥10 μm are generally excluded from such considerations. Where the particles themselves are chemically heterogeneous, as in an urban context, this may be inappropriate. Clearly all air-borne particles, whether coarse or fine, are susceptible to inhalation. Hence, the possibility exists for any adhering potentially harmful semi-volatile substances to be subsequently de-sorbed in vivo thereby facilitating their transport deeper into the lungs. Consequently, this alone may be a sufficient reason for including rather than rejecting during air quality monitoring the relatively coarse 10–100 μm particle fraction, ideally in conjunction with routine estimation of the gaseous co-pollutants thereby facilitating a multi-pollutant approach apropos regulation.
Keywords: Air Quality Index; Health effects; Standards; Particulate matter; Semi-volatiles; Surrogate;
Corrigendum to “New indices for wet scavenging of air pollutants (O3, CO, NO2, SO2, and PM10) by summertime rain” [Atmos. Environ. 82 (2014) 226–237] by Jung-Moon Yoo; Yu-Ri Lee; Dongchul Kim; Myeong-Jae Jeong; William R. Stockwell; Prasun K. Kundu; Soo-Min Oh; Dong-Bin Shin; Suk-Jo Lee (178).
Corrigendum to “Nitrated polycyclic aromatic hydrocarbon pollution during the Shanghai World Expo 2010” [Atmos. Environ. 89 (2014) 242–248] by W. Wang; L. Jing; J. Zhan; B. Wang; D.P. Zhang; H.W. Zhang; D.Q. Wang; Y. Yang; J. Zhao; Y.F. Sun; X.H. Bi; X.T. Wang; J.L. Feng (179-180).