| 11. |
- Cho, Chaeyoon, et al.
(author)
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Observation-based estimates of the mass absorption cross-section of black and brown carbon and their contribution to aerosol light absorption in East Asia
- 2019
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 212, s. 65-74
-
Journal article (peer-reviewed)abstract
- In this study, we estimated the contribution of black carbon (BC) and brown carbon (BrC) to aerosol light absorption from surface in-situ and aerosol robotic network (AERONET) columnar observations. The mass absorption cross-section (MAC) of BC (MAC(BC)) was estimated to be 6.4 +/- 1.5 m(2) g(-1) at 565 mn from in-situ aerosol measurements at Gosan Climate Observatory (GCO), Korea, in January 2014, which was lower than those observed in polluted urban areas. A BrC MAC of 0.62 +/- 0.06 m(2) g(-1) (565 mn) in our estimate is approximately ten times lower than MACK at 565 nm. The contribution of BC and BrC to the carbonaceous aerosol absorption coefficient at 565 nm from the in-situ measurements was estimated at 88.1 +/- 7.4% and 11.9 +/- 7.4%, respectively at GCO. Similarly, the contribution of BC and BrC to the absorption aerosol optical depth (AAOD) for carbonaceous aerosol (CA), constrained by AERONET observations at 14 sites over East Asia by using different spectral dependences of the absorption (i.e., absorption Angstrom exponent) of BC and BrC, was 84.9 +/- 2.8% and 15.1 +/- 2.8% at 565 nm, respectively. The contribution of BC to CA AAOD was greater in urban sites than in the background areas, whereas the contribution of BrC to CA AAOD was higher in background sites. The overall contribution of BC to CA AAOD decreased by 73%-87% at 365 nm, and increased to 93%-97% at 860 nm. The contribution of BrC to CA AAOD decreased significantly with increasing wavelength from approximately 17% at 365 nm to 4% at 860 nm.
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| 12. |
- Cirino, Glauber, et al.
(author)
-
Observations of Manaus urban plume evolution and interaction with biogenic emissions in GoAmazon 2014/5
- 2018
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 191, s. 513-524
-
Journal article (peer-reviewed)abstract
- As part of the Observations and Modeling of the Green Ocean Amazon (GoAmazon 2014/5) Experiment, detailed aerosol and trace gas measurements were conducted near Manaus, a metropolis located in the central Amazon Basin. Measurements of aerosol particles and trace gases were done downwind Manaus at the sites T2 (Tiwa Hotel) and T3 (Manacapuru), at a distance of 8 and 70 km from Manaus, respectively. Based on in-plume measurements closer to Manaus (site T2), the chemical signatures of city emissions were used to improve the interpretation of pollutant levels at the T3 site. We derived chemical and physical properties for the city's atmospheric emission ensemble, taking into account only air masses impacted by the Manaus plume at both sites, during the wet and dry season Intensive Operating Periods (IOPs). At T2, average concentrations of aerosol number (CN), CO and SO2 were 5500 cm(-3) (between 10 and 490 nm), 145 ppb and 0.60 ppb, respectively, with a typical ratio ACN/ACO of 60-130 particles cm(-3) ppb(-1). The aerosol scattering (at RH < 60%) and absorption at 637 nm at T2 ranged from 10 to 50 M m(-1) and 5-10 M m(-1), respectively, leading to a mean single scattering albedo (SSA) of 0.70. In addition to identifying periods dominated by Manaus emissions at both T2 and T3, the plume transport between the two sampling sites was studied using back trajectory calculations. Results show that the presence of the Manaus plume at site T3 was important mainly during the daytime and at the end of the afternoons. During time periods directly impacted by Manaus emissions, an average aerosol number concentration of 3200 cm(-3) was measured at T3. Analysis of plume evolution between T2 and T3 indicates a transport time of 4-5 h. Changes of submicron organic and sulfate aerosols ratios relative to CO (Delta OA/Delta CO and Delta SO4/Delta CO, respectively) indicate significant production of secondary organic aerosol (SOA), corresponding to a 40% mass increase in OA and a 30% in SO4 mass concentration. Similarly, during air mass arrival at T3 the SSA increased to 0.83 from 0.70 at T2, mainly associated with an increase in organic aerosol concentration. Aerosol particle size distributions show a strong decrease in the Aitken nuclei mode (10-100 nm) during the transport from T2 to T3, in particular above 30 nm, as a result of efficient coagulation processes into larger particles. A decrease of 30% in the particle number concentration and an increase of about 50 nm in geometric mean diameter were observed from T2 to T3 sites. The study of the evolution of aerosol properties downwind of the city of Manaus improves our understanding of how coupling of anthropogenic and biogenic sources may be impacting the sensitive Amazonian atmosphere.
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| 13. |
- Ciuzas, Darius, et al.
(author)
-
Characterization of indoor aerosol temporal variations for the real-time management of indoor air quality
- 2015
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 118, s. 107-117
-
Journal article (peer-reviewed)abstract
- The study presents the characterization of dynamic patterns of indoor particulate matter (PM) during various pollution episodes for real-time IAQ management. The variation of PM concentrations was assessed for 20 indoor activities, including cooking related sources, other thermal sources, personal care and household products. The pollution episodes were modelled in full-scale test chamber representing a standard usual living room with the forced ventilation of 0.5 h(-1). In most of the pollution episodes, the maximum concentration of particles in exhaust air was reached within a few minutes. The most rapid increase in particle concentration was during thermal source episodes such as candle, cigarette, incense stick burning and cooking related sources, while the slowest decay of concentrations was associated with sources, emitting ultrafine particle precursors, such as furniture polisher spraying, floor wet mopping with detergent etc. Placement of the particle sensors in the ventilation exhaust vs. in the centre of the ceiling yielded comparable results for both measured maximum concentrations and temporal variations, indicating that both locations were suitable for the placement of sensors for the management of IAQ. The obtained data provides information that may be utilized considering measurements of aerosol particles as indicators for the real-time management of IAQ. (C) 2015 Elsevier Ltd. All rights reserved.
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| 14. |
- Córdoba-Jabonero, Carmen, et al.
(author)
-
Performance of a dust model to predict the vertical mass concentration of an extreme Saharan dust event in the Iberian Peninsula : Comparison with continuous, elastic, polarization-sensitive lidars
- 2019
-
In: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 214
-
Journal article (peer-reviewed)abstract
- An intense dusty event unusually occurred in wintertime over the Iberian Peninsula was detected over two Spanish NASA/MPLNET sites: the temporary Torrejón Observational Tower for Environmental Monitoring (TOTEM, 40.5°N 3.5°W) and the Barcelona station (BCN, 41.4°N 2.1°E). The highest dust incidence was observed from 22 to 23 February 2017; this two-day dusty scenario is examined in order to evaluate the performance of the operational NMMB/BSC-Dust model on forecasted mass concentration profiling in comparison with polarized Micro-Pulse (P-MPL) mass estimates for dust particles. First, the optical properties of the dust (DD) were effectively separated from the non-dust (ND) component by using the combined P-MPL/POLIPHON method. Lidar-derived DD optical depths reached maximums of 1.6–1.7 (±0.1) at both stations. Typical features for dust were obtained: linear particle depolarization ratios between 0.3 and 0.4, and lidar ratios in the range of 41–70 sr and 36–66 sr, respectively, for TOTEM and BCN. Lower AERONET Ångström exponents were reported for TOTEM (0.12 ± 0.04) than at BCN (0.5 ± 0.3). HYSPLIT back-trajectory analysis showed air masses coming from the Sahara region, mostly transporting dust particles. AERONET-derived Mass Extinction Efficiencies (MEE) under dusty conditions were used for the extinction-to-mass conversion procedure as applied to the P-MPL measurements: MEE values were lower at TOTEM (0.57 ± 0.01 m2 g−1) than those found at BCN (0.87 ± 0.10 m2 g−1). Those results reveal that dust particles were predominantly larger at TOTEM than those observed at BCN, and a longer transport of dust particles from the Sahara sources to BCN could favour a higher gravitational settling of coarser particles before reaching BCN than TOTEM. A comparative analysis between profiles as obtained from the lidar DD component of the mass concentration and those forecasted by the NMMB/BSC-Dust model (25 available dusty profiles) was performed. The degree of agreement between both datasets was determined by the percentage of dusty cases satisfying selected model performance criteria (favourable cases) of two proxies: the Mean Fractional Bias, MFB" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">MFBMFB, and the correlation coefficient, CC" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">CCCC. A good agreement is found (72% and 76%, respectively, of favourable cases); however, large discrepancies are found at low altitudes between the dust model and the lidar observations, mostly at early stages of the arrival of the dust intrusion. Higher model-derived centre-of-mass (CoM) heights are found in 60% of the cases (with differences < 15% w.r.t. the lidar CoM, whose values ranged between 1.8 and 2.3 km height). In addition, modelled mass loading (ML) values were generally higher than the lidar-derived ones. However, the evolution of the mass loading along the two days, 22 and 23 February, was rather similar for both the model forecasting and lidar observations at both stations. The relative ML differences (<50%) of the mass loading represented 60% of all cases. Discrepancies can be based on the uncertainties in the lidar retrievals (mainly, the use of single extinction-to-mass conversion factors). In general, a moderately good agreement is observed between the P-MPL-derived dust mass concentration profiles and the NMMB/BSC-Dust model ones at both sites; large discrepancies are found at lower altitudes, plausibly due to a lower sedimentation of dust particles coming from upper layers by gravitational settling than that introduced by the NMMB/BSC-Dust model in the simulations. The methodology described for the dust model evaluation against the continuous P-MPL observations can be easily adopted for an operational use of the NMMB/BSC-Dust model for forecasting the mass concentration profiling in frequently dust-affected regions with serious climate and environmental implications, as long as a typical MEE for dust could be accurately specified. Hence, a statistical analysis for determining AERONET-based MEE values over the Iberian Peninsula is on-going.
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| 15. |
- de Almeida, Daniela S., et al.
(author)
-
Genotoxic effects of daily personal exposure to particle mass and number concentrations on buccal cells
- 2018
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 176, s. 148-157
-
Journal article (peer-reviewed)abstract
- The aim of this study is to assess personal exposure to Particle Number Concentrations (PNC) in four size ranges between 0.3 and 10 μm, and particulate matter (PM1; PM2.5; PM4; PM10) in order to evaluate possible genotoxic effects through a comet assay in buccal cells. A convenience cohort of 30 individuals from a Brazilian medium-sized city was selected. These individuals aged between 20 and 61 and worked in typical job categories (i.e., administrative, commerce, education, general services and transport). They were recruited to perform personal exposure measurements during their typical daily routine activities, totaling 240 h of sampling. The 8-h average mass concentrations in air for volunteers ranged from 2.4 to 31.8 μg m−3 for PM1, 4.2–45.1 μg m−3 for PM2.5, 7.9–66.1 μg m−3 for PM4 and from 23.1 to 131.7 μg m−3 for PM10. The highest PNC variation was found for 0.3–0.5 range, between 14 and 181 particles cm−3, 1 to 14 particles cm−3 for the 0.5–1.0 range, 0.2 to 2 particles cm−3 for the 1.0–2.5 range, and 0.06 to 0.7 particles cm−3 for the 2.5–10 range. Volunteers in the ‘education’ category experienced the lowest inhaled dose of PM2.5 as opposed to those involved in ‘commercial‘ activities with the highest doses for PM10 (1.63 μg kg−1 h−1) and PM2.5 (0.61 μg kg−1 h−1). The predominant cause for these high doses was associated with the proximity of the workplace to the street and vehicle traffic. The comet assay performed in buccal cells indicated that the volunteers in ‘commerce’ category experienced the highest damage to their DeoxyriboNucleic Acid (DNA) compared with the control category (i.e. ‘education’). These results indicate the variability in personal exposure of the volunteers in different groups, and the potential damage to DNA was much higher for those spending time in close proximity to the vehicle sources (e.g. commercial services) leading to exposure to a higher fraction of fine particles. This study builds understanding on the exposure of people in different job categories, and provide policy makers with useful information to tackle this neglected issue.
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| 16. |
- Degerman, Erik, et al.
(author)
-
Long term trends of fish after liming of Swedish streams and lakes
- 2016
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 146, s. 245-251
-
Journal article (peer-reviewed)abstract
- Thousands of Swedish acidified lakes and streams have been regularly limed for about 30 years. Standard sampling of fish assemblages in lakes and streams was an important part of monitoring the trends after liming, i.e. sampling with multi-mesh gillnets in lakes (EN 14757) and electrofishing in streams (EN 14011). Monitoring data are nationally managed, in the National Register of Survey test-fishing and the Swedish Electrofishing Register. We evaluated long-term data from 1029 electrofishing sites in limed streams and gillnet sampling in 750 limed lakes, along with reference data from 195 stream sites and 101 lakes with no upstream liming in their catchments. The median year of first liming was 1986 for both streams and lakes. The proportion of limed stream sites with no fish clearly decreased with time, mean species richness and proportion of sites with brown trout (Salmo trutta) recruits increased. There were no consistent trends in fish occurrence or species richness at non-limed sites, but occurrence of brown trout recruits also increased in acid as well as neutral reference streams. Abundance of brown trout, perch (Perca fluviatilis) and roach (Rutilus rutilus) increased significantly more at limed sites than at non-limed reference sites sampled before and after 1986. The mean species richness did not change consistently in limed lakes, but decreased in low alkalinity reference lakes, and fish abundance decreased significantly in limed as well as in non-limed lakes.
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| 17. |
- Denby, B. R., et al.
(author)
-
Road salt emissions : A comparison of measurements and modelling using the NORTRIP road dust emission model
- 2016
-
In: Atmospheric Environment. - : Elsevier Ltd. - 1352-2310 .- 1873-2844. ; 141, s. 508-522
-
Journal article (peer-reviewed)abstract
- De-icing of road surfaces is necessary in many countries during winter to improve vehicle traction. Large amounts of salt, most often sodium chloride, are applied every year. Most of this salt is removed through drainage or traffic spray processes but a certain amount may be suspended, after drying of the road surface, into the air and will contribute to the concentration of particulate matter. Though some measurements of salt concentrations are available near roads, the link between road maintenance salting activities and observed concentrations of salt in ambient air is yet to be quantified. In this study the NORTRIP road dust emission model, which estimates the emissions of both dust and salt from the road surface, is applied at five sites in four Nordic countries for ten separate winter periods where daily mean ambient air measurements of salt concentrations are available. The model is capable of reproducing many of the salt emission episodes, both in time and intensity, but also fails on other occasions. The observed mean concentration of salt in PM10, over all ten datasets, is 4.2 μg/m3 and the modelled mean is 2.8 μg/m3, giving a fractional bias of −0.38. The RMSE of the mean concentrations, over all 10 datasets, is 2.9 μg/m3 with an average R2 of 0.28. The mean concentration of salt is similar to the mean exhaust contribution during the winter periods of 2.6 μg/m3. The contribution of salt to the kerbside winter mean PM10 concentration is estimated to increase by 4.1 ± 3.4 μg/m3 for every kg/m2 of salt applied on the road surface during the winter season. Additional sensitivity studies showed that the accurate logging of salt applications is a prerequisite for predicting salt emissions, as well as good quality data on precipitation. It also highlights the need for more simultaneous measurements of salt loading together with ambient air concentrations to help improve model parameterisations of salt and moisture removal processes. © 2016 The Authors
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| 18. |
- Deng, Qihong, et al.
(author)
-
Association between prenatal exposure to industrial air pollution and onset of early childhood ear infection in China
- 2017
-
In: Atmospheric Environment. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1352-2310 .- 1873-2844. ; 157, s. 18-26
-
Journal article (peer-reviewed)abstract
- Background: Otitis media (OM) is a common infection in early childhood with repeated attacks that lead to long-term complications and sequelae, but its etiology still remains unclear. Objective: To examine the association between early life exposure to air pollution and childhood OM, with the purpose of identifying critical windows of exposure and key components of air pollution in the development of OM. Methods: We conducted a prospective cohort study of 1617 children aged 3-4 years in Changsha, China (2011-2012). The prevalence of OM was assessed by a questionnaire administered by the parents. Individual exposures to nitrogen dioxide (NO2), sulfur dioxide (SO2) and particulate matter with an aerodynamic diameter <= 10 gm (PM10) during prenatal, postnatal, and current windows were estimated using the measured concentrations at monitoring stations. We used logistic regression model to examine the OM risk in terms of odds ratio (OR) and 95% confidence interval (CI) for exposure to different air pollutants during different timing windows, adjusting for covariates, multi-pollutants, and multi windows. Results: Life-time prevalence of doctor-diagnosed OM in preschool children in Changsha was 7.3%. Childhood OM was associated only with prenatal exposure to the industrial air pollution with adjusted OR (95% CI) = 1.44 (1.09-1.88) for a 27 g/m(3) increase in SO2, particularly during the first trimester of pregnancy. We further found that prenatal SO2 exposure was not associated with the repeated attacks but was associated with the onset of OM, adjusted OR (95% CI) = 1.47 (1.10-1.96). The association between prenatal SO2 exposure and early childhood OM was robust after adjusting for other pollutants and windows. Sensitivity analysis indicated that the association was stronger in females, children with parental atopy, and children living in houses with cockroaches, new redecoration, and condensation on window pane during winter. Conclusion: We provide new evidence that prenatal exposure to industrial air pollution is associated with early childhood OM in China and may contribute to the onset of childhood OM. Our findings are helpful in developing more effective preventative strategies for childhood OM. (C) 2017 Elsevier Ltd. All rights reserved.
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| 19. |
- Dingwell, Adam, et al.
(author)
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Seasonal and diurnal patterns in the dispersion of SO2 from Mt. Nyiragongo
- 2016
-
In: Atmospheric Environment. - : Elsevier BV. - 1873-2844 .- 1352-2310. ; 132, s. 19-29
-
Journal article (peer-reviewed)abstract
- Mt. Nyiragongo is an active volcano located in the Democratic Republic of Congo, close to the border of Rwanda and about 15 km north of the city of Goma (~ 1,000,000 inhabitants). Gases emitted from Nyiragongo might pose a persistent hazard to local inhabitants and the environment. While both ground- and satellite-based observations of the emissions exist, prior to this study, no detailed analysis of the dispersion of the emissions have been made. We have conducted a dispersion study, using a modelling system to determine the geographical distribution of SO2.A combination of a meteorological model (WRF), a Lagrangian particle dispersion model (FLEXPART-WRF) and flux data based on DOAS measurements from the NOVAC-network is used. Since observations can only be made during the day, we use random sampling of fluxes and ensemble modelling to estimate night-time emissions.Seasonal variations in the dispersion follows the migration of the Inter Tropical Convergence Zone. In June-August, the area with the highest surface concentrations is located to the northwest, and in December-February, to the southwest of the source. Diurnal variations in surface concentrations were determined by the development of the planetary boundary layer and the lake-/land breeze cycle around lake Kivu. Both processes contribute to low surface concentrations during the day and high concentrations during the night. However, the strong northerly trade winds in November-March weakened the lake breeze, contributing to higher daytime surface concentrations along the northern shore of Lake Kivu, including the city of Goma. For further analysis and measurements, it is important to include both seasonal and diurnal cycles in order to safely cover periods of high and potentially hazardous concentrations.
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| 20. |
- Dore, A. J., et al.
(author)
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Evaluation of the performance of different atmospheric chemical transport models and inter-comparison of nitrogen and sulphur deposition estimates for the UK
- 2015
-
In: Atmospheric Environment. - : Elsevier BV. - 1873-2844 .- 1352-2310. ; 119, s. 131-143
-
Journal article (peer-reviewed)abstract
- An evaluation has been made of a number of contrasting atmospheric chemical transport models, of varying complexity, applied to estimate sulphur and nitrogen deposition in the UK. The models were evaluated by comparison with annually averaged measurements of gas, aerosol and precipitation concentrations from the national monitoring networks. The models were evaluated in relation to performance criteria. They were generally able to satisfy a criterion of 'fitness for purpose' that at least 50% of modelled concentrations should be within a factor of two of measured values. The second criterion, that the magnitude of the normalised mean bias should be less than 20%, was not always satisfied. Considering known uncertainties in measurement techniques, this criterion may be too strict. Overall, simpler models were able to give a good representation of measured gas concentrations whilst the use of dynamic meteorology, and complex photo-chemical reactions resulted complex models. The models were compared graphically by plotting maps and cross-country transects of wet and dry deposition as well as calculating budgets of total wet and dry deposition to the UK for sulphur, oxidised nitrogen and reduced nitrogen. The total deposition to the UK varied by 22-36% amongst the different models depending on the deposition component. At a local scale estimates of both dry and wet deposition for individual 5 km x 5 km model grid squares were found to vary between the different models by up to a factor of 4.
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