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  • Diurnal, seasonal, and annual trends in tropospheric CO in Southwest London during 2000–2015: Wind sector analysis and comparisons with urban and remote sites
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-17
    Iván Y. Hernández-Paniagua, David Lowry, Kevin C. Clemitshaw, Paul I. Palmer, Rebecca E. Fisher, James L. France, Alberto Mendoza, Simon O'Doherty, Grant Forster, M. Lanoisellé, Euan G. Nisbet
    更新日期:2018-01-17
  • Different approaches to assess the environmental performance of a cow manure biogas plant
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-17
    Marta Torrellas, Laura Burgos, Laura Tey, Joan Noguerol, Victor Riau, Jordi Palatsi, Assumpció Antón, Xavier Flotats, August Bonmatí
    更新日期:2018-01-17
  • The isotopic composition of CO in vehicle exhaust
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-12
    S. Naus, T. Röckmann, M.E. Popa

    We investigated the isotopic composition of CO in the exhaust of individual vehicles. Additionally, the CO2 isotopes, and the CO:CO2, CH4:CO2 and H2:CO gas ratios were measured. This was done under idling and revving conditions, and for three vehicles in a full driving cycle on a testbench. The spread in the results, even for a single vehicle, was large: for δ13δ13C in CO ∼ −60 to 0‰, for δ18δ18O in CO ∼ +10 to +35‰, and for all gas ratios several orders of magnitude. The results show an increase in the spread of isotopic values for CO compared to previous studies, suggesting that increasing complexity of emission control in vehicles might be reflected in the isotopic composition. When including all samples, we find a weighted mean for the δ13δ13C and δ18δ18O in CO of −28.7 ± 0.5‰ and +24.8 ± 0.3‰ respectively. This result is dominated by cold petrol vehicles. Diesel vehicles behaved as a distinct group, with CO enriched in 13C and depleted in 18O, compared to petrol vehicles.For the H2:CO ratio of all vehicles, we found a value of 0.71 ± 0.31 ppb:ppb. The CO:CO2 ratio, with a mean of 19.4 ± 6.8 ppb:ppm, and the CH4:CO2 ratio, with a mean of 0.26 ± 0.05 ppb:ppm, are both higher than recent literature indicates. This is likely because our sampling distribution was biased towards cold vehicles, and therefore towards higher emission situations. The CH4:CO2 ratio was found to behave similarly to the CO:CO2 ratio, suggesting that the processes affecting CO and CH4 are similar.The δ13δ13C values in CO2 were close to the expected δ13δ13C in fuel, with no significant difference between petrol and diesel vehicles. The δ18δ18O values in CO2 for petrol vehicles covered a range of 20–35‰, similar to the δ18δ18O of CO. The δ18δ18O values in CO2 for diesel vehicles were close to the δ18δ18O in atmospheric oxygen.A set of polluted atmospheric samples, taken near a highway and inside parking garages, showed an isotopic signature of CO and a H2:CO ratio that were similar the high emitters in the individual vehicle measurements, with no significant differences between parking garage and highway samples. This suggests that in both environments, which are dominated by different driving conditions, the CO emissions from high emitters (either a few high emission vehicles, or many vehicles with brief bursts of high emissions) dominate the total traffic emissions.

    更新日期:2018-01-12
  • Formation of aqueous-phase sulfate during the haze period in China: Kinetics and atmospheric implications
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-11
    Haijie Zhang, Shilu Chen, Jie Zhong, Shaowen Zhang, Yunhong Zhang, Xiuhui Zhang, Zesheng Li, Xiaocheng Zeng

    Sulfate is one of the most important components in the aerosol due to its key role in air pollution and global climate change. Recent work has suggested that reactive nitrogen chemistry in aqueous water can explain the missing source of sulfate in the aqueous water. Herein, we have mapped out the energy profile of the oxidization process of SO2 leading from NO2 and two feasible three-step mechanisms have been proposed. For the oxidation of HOSO2− and HSO3− by the dissolved NO2 in weakly acidic and neutral aerosol (pH ≤ ≤ 7), the main contribution to the missing sulfate production comes from the oxidation of HOSO2−. The whole process is a self-sustaining process. For the oxidation of SO32− in alkaline aerosol (pH > 7), the third step - decomposition step of H2O or hydrolysis of SO3 step which are two parallel processes are the rate-limiting steps. The present results are of avail to better understand the missing source of sulfate in the aerosol and hence may lead to better science-based solutions for resolving the severe haze problems in China.

    更新日期:2018-01-11
  • Decrease of VOC emissions from vehicular emissions in Hong Kong from 2003 to 2015: Results from a tunnel study
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-10
    Long Cui, Xiao Liang Wang, Kin Fai Ho, Yuan Gao, Chang Liu, Steven Sai Hang Ho, Hai Wei Li, Shun Cheng Lee, Xin Ming Wang, Bo Qiong Jiang, Yu Huang, Judith C. Chow, John G. Watson, Lung-Wen Chen

    Vehicular emissions are one of major anthropogenic sources of ambient volatile organic compounds (VOCs) in Hong Kong. During the past twelve years, the government of the Hong Kong Special Administrative Region has undertaken a series of air pollution control measures to reduce vehicular emissions in Hong Kong. Vehicular emissions were characterized by repeated measurement in the same roadway tunnel in 2003 and 2015. The total net concentration of measured VOCs decreased by 44.7% from 2003 to 2015. The fleet-average VOC emission factor decreased from 107.1 ± 44.8 mg veh−1 km−1 in 2003 to 58.8 ± 50.7 mg veh−1 km−1 in 2015, and the total ozone (O3) formation potential of measured VOCs decreased from 474.1 mg O3 veh−1 km−1 to 190.8 mg O3 veh−1 km−1. The emission factor of ethene, which is one of the key tracers for diesel vehicular emissions, decreased by 67.3% from 2003 to 2015 as a result of the strict control measures on diesel vehicular emissions. Total road transport VOC emissions is estimated to be reduced by 40% as compared with 2010 by 2020, which will be an important contributor to achieve the goal of total VOC emission reduction in the Pearl River Delta region. The large decrease of VOC emissions from on-road vehicles demonstrates the effectiveness of past multi-vehicular emission control strategy in Hong Kong.

    更新日期:2018-01-11
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  • Impacts of a large boreal wildfire on ground level atmospheric concentrations of PAHs, VOCs and ozone
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-10
    Gregory R. Wentworth, Yayne-Abeba Aklilu, Matthew S. Landis, Yu-Mei Hsu
    更新日期:2018-01-10
  • Four dimensional data assimilation (FDDA) impacts on WRF performance in simulating inversion layer structure and distributions of CMAQ-simulated winter ozone concentrations in Uintah Basin
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-09
    Trang Tran, Huy Tran, Marc Mansfield, Seth Lyman, Erik Crosman

    Four-dimensional data assimilation (FDDA) was applied in WRF-CMAQ model sensitivity tests to study the impact of observational and analysis nudging on model performance in simulating inversion layers and O3 concentration distributions within the Uintah Basin, Utah, U.S.A. in winter 2013. Observational nudging substantially improved WRF model performance in simulating surface wind fields, correcting a 10 °C warm surface temperature bias, correcting overestimation of the planetary boundary layer height (PBLH) and correcting underestimation of inversion strengths produced by regular WRF model physics without nudging. However, the combined effects of poor performance of WRF meteorological model physical parameterization schemes in simulating low clouds, and warm and moist biases in the temperature and moisture initialization and subsequent simulation fields, likely amplified the overestimation of warm clouds during inversion days when observational nudging was applied, impacting the resulting O3 photochemical formation in the chemistry model. To reduce the impact of a moist bias in the simulations on warm cloud formation, nudging with the analysis water mixing ratio above the planetary boundary layer (PBL) was applied. However, due to poor analysis vertical temperature profiles, applying analysis nudging also increased the errors in the modeled inversion layer vertical structure compared to observational nudging. Combining both observational and analysis nudging methods resulted in unrealistically extreme stratified stability that trapped pollutants at the lowest elevations at the center of the Uintah Basin and yielded the worst WRF performance in simulating inversion layer structure among the four sensitivity tests. The results of this study illustrate the importance of carefully considering the representativeness and quality of the observational and model analysis data sets when applying nudging techniques within stable PBLs, and the need to evaluate model results on a basin-wide scale.

    更新日期:2018-01-10
  • The first countrywide monitoring of selected POPs: Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and selected organochlorine pesticides (OCPs) in the atmosphere of Turkey
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-09
    Perihan Binnur Kurt-Karakus, Tugba Ugranli-Cicek, Sait C. Sofuoglu, Halil Celik, Elif Gungormus, Kadir Gedik, Aysun Sofuoglu, Hatice Eser Okten, Askın Birgul, Henry Alegria, Kevin C. Jones
    更新日期:2018-01-09
  • Source characterization and exposure modeling of gas-phase polycyclic aromatic hydrocarbon (PAH) concentrations in Southern California
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-08
    Shahir Masri, Lianfa Li, Andy Dang, Judith H. Chung, Jiu-Chiuan Chen, Zhi-Hua (Tina) Fan, Jun Wu

    Airborne exposures to polycyclic aromatic hydrocarbons (PAHs) are associated with adverse health outcomes. Because personal air measurements of PAHs are labor intensive and costly, spatial PAH exposure models are useful for epidemiological studies. However, few studies provide adequate spatial coverage to reflect intra-urban variability of ambient PAHs. In this study, we collected 39–40 weekly gas-phase PAH samples in southern California twice in summer and twice in winter, 2009, in order to characterize PAH source contributions and develop spatial models that can estimate gas-phase PAH concentrations at a high resolution. A spatial mixed regression model was constructed, including such variables as roadway, traffic, land-use, vegetation index, commercial cooking facilities, meteorology, and population density. Cross validation of the model resulted in an R2 of 0.66 for summer and 0.77 for winter. Results showed higher total PAH concentrations in winter. Pyrogenic sources, such as fossil fuels and diesel exhaust, were the most dominant contributors to total PAHs.PAH sources varied by season, with a higher fossil fuel and wood burning contribution in winter. Spatial autocorrelation accounted for a substantial amount of the variance in total PAH concentrations for both winter (56%) and summer (19%). In summer, other key variables explaining the variance included meteorological factors (9%), population density (15%), and roadway length (21%). In winter, the variance was also explained by traffic density (16%). In this study, source characterization confirmed the dominance of traffic and other fossil fuel sources to total measured gas-phase PAH concentrations while a spatial exposure model identified key predictors of PAH concentrations. Gas-phase PAH source characterization and exposure estimation is of high utility to epidemiologist and policy makers interested in understanding the health impacts of gas-phase PAHs and strategies to reduce emissions.

    更新日期:2018-01-09
  • Relationship between AOD and synoptic circulation over the Eastern Mediterranean: A comparison between subjective and objective classifications
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-08
    Shalev Bodenheimer, Ronit Nirel, Itamar Lensky, Uri Dayan

    The Eastern Mediterranean (EM) Basin is strongly affected by dust originating from two of the largest world sources: The Sahara Desert and the Arabian Peninsula. Climatologically, the distribution pattern of aerosol optical depth (AOD), as proxy to particulate matter (PM), is known to be correlated with synoptic circulation.The climatological relationship between circulation type classifications (CTCs) and AOD levels over the EM Basin ("synoptic skill") was examined for the years 2000–2014. We compared the association between subjective (expert-based) and objective (fully automated) classifications and AOD using autoregressive models. After seasonal adjustment, the mean values of R2 for the different methods were similar. However, the distinct spatial pattern of the R2 values suggests that subjective classifications perform better in their area of expertise, specifically in the southeast region of the study area, while, objective CTCs had better synoptic skill over the northern part of the EM. This higher synoptic skill of subjective CTCs stem from their ability to identify distinct circulation types (e.g. Sharav lows and winter lows) that are infrequent but are highly correlated with AOD. Notably, a simple CTC based on seasonality rather than meteorological parameters predicted well AOD levels, especially over the south-eastern part of the domain.Synoptic classifications that are area-oriented are likely better predictors of AOD and possibly other environmental variables.

    更新日期:2018-01-09
  • Analysis of multi-year near-surface ozone observations at the WMO/GAW “Concordia” station (75°06′S, 123°20′E, 3280 m a.s.l. – Antarctica)
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-08
    Paolo Cristofanelli, Davide Putero, Paolo Bonasoni, Maurizio Busetto, Francescopiero Calzolari, Paolo Grigioni, Giuseppe Camporeale, Angelo Lupi, Boyan Petkov, Rita Traversi, Roberto Udisti, Vito Vitale

    This work focuses on the near-surface O3 variability over the eastern Antarctic Plateau. In particular, eight years (2006–2013) of continuous observations at the WMO/GAW contributing station “Concordia” (Dome C–DMC: 75°06′S, 123°20′E, 3280 m) are presented, in the framework of the Italian Antarctic Research Programme (PNRA). First, the characterization of seasonal and diurnal O3 variability at DMC is provided. Then, for the period of highest data coverage (2008–2013), we investigated the role of specific atmospheric processes in affecting near-surface summer O3 variability, when O3 enhancement events (OEEs) are systematically observed at DMC (average monthly frequency peaking up to 60% in December). As deduced by a statistical selection methodology, these OEEs are affected by a significant interannual variability, both in their average O3 values and in their frequency. To explain part of this variability, we analyzed OEEs as a function of specific atmospheric variables and processes: (i) total column of O3 (TCO) and UV-A irradiance, (ii) long-range transport of air masses over the Antarctic Plateau (by Lagrangian back-trajectory analysis – LAGRANTO), (iii) occurrence of “deep” stratospheric intrusion events (by using the Lagrangian tool STLEFLUX). The overall near-surface O3 variability at DMC is controlled by a day-to-day pattern, which strongly points towards a dominating influence of processes occurring at “synoptic” scales rather than “local” processes. Even if previous studies suggested an inverse relationship between OEEs and TCO, we found a slight tendency for the annual frequency of OEEs to be higher when TCO values are higher over DMC. The annual occurrence of OEEs at DMC seems related to the total time spent by air masses over the Antarctic plateau before their arrival to DMC, suggesting the accumulation of photochemically-produced O3 during the transport, rather than a more efficient local production. Moreover, the identification of recent (i.e., 4-day old) stratospheric intrusion events by STEFLUX suggested only a minor influence (up to 3% of the period, in November) of “deep” events on the variability of near-surface summer O3 at DMC.

    更新日期:2018-01-08
  • Experimental study on the particulate matter and nitrogenous compounds from diesel engine retrofitted with DOC+CDPF+SCR
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-08
    Yun-Hua Zhang, Di-Ming Lou, Pi-Qiang Tan, Zhiyuan Hu

    The increasingly stringent emission regulations will mandate the retrofit of after-treatment devices for in-use diesel vehicles, in order to reduce their substantial particulate matter and nitrogen oxides (NOX) emissions. In this paper, a combination of DOC (diesel oxidation catalyst), CDPF (catalytic diesel particulate filter) and SCR (selective catalytic reduction) retrofit for a heavy-duty diesel engine was employed to perform experiment on the engine test bench to evaluate the effects on the particulate matter emissions including particle number (PN), particle mass (PM), particle size distributions and nitrogenous compounds emissions including NOX, nitrogen dioxide (NO2)/NOX, nitrous oxide (N2O) and ammonia (NH3) slip. In addition, the urea injection was also of our concern. The results showed that the DOC + CDPF + SCR retrofit almost had no adverse effect on the engine power and fuel consumption. Under the test loads, the upstream DOC and CDPF reduced the PN and PM by an average of 91.6% and 90.9%, respectively. While the downstream SCR brought about an average decrease of 85% NOX. Both PM and NOX emission factors based on this retrofit were lower than China-Ⅳ limits (ESC), and even lower than China-Ⅴ limits (ESC) at medium and high loads. The DOC and CDPF changed the particle size distributions, leading to the increase in the proportion of accumulation mode particles and the decrease in the percentage of nuclear mode particles. This indicates that the effect of DOC and CDPF on nuclear mode particles was better than that of accumulation mode ones. The upstream DOC could increase the NO2/NOX ratio to 40%, higher NO2/NOX ratio improved the efficiency of CDPF and SCR. Besides, the N2O emission increased by an average of 2.58 times after the retrofit and NH3 slip occurred with the average of 26.7 ppm. The rate of urea injection was roughly equal to 8% of the fuel consumption rate. The DOC + CDPF + SCR retrofit was proved a feasible and effective measurement in terms of reducing particulate emissions and NOX simultaneously for in-use engine. However, it also resulted in higher N2O emission, NH3 slip as well as urea injecting strategy problem which should be of further concern.

    更新日期:2018-01-08
  • On-site ocean horizontal aerosol extinction coefficient inversion under different weather conditions on the Bo-hai and Huang-hai Seas
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-06
    Xianjiang Zeng, Min Xia, Yinghui Ge, Wenping Guo, Kecheng Yang

    In this paper, we explore the horizontal extinction characteristics under different weather conditions on the ocean surface with on-site experiments on the Bo-hai and Huang-hai Seas in the summer of 2016. An experimental lidar system is designed to collect the on-site experimental data. By aiming at the inhomogeneity and uncertainty of the horizontal aerosol in practice, a joint retrieval method is proposed to retrieve the aerosol extinction coefficients (AEC) from the raw data along the optical path. The retrieval results of both the simulated and the real signals demonstrate that the joint retrieval method is practical. Finally, the sequence observation results of the on-site experiments under different weather conditions are reported and analyzed. These results can provide the attenuation information to analyze the atmospheric aerosol characteristics on the ocean surface.

    更新日期:2018-01-06
  • Impact of parameterization choices on the restitution of ozone deposition over vegetation
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-06
    Aurélie Le Morvan-Quéméner, Isabelle Coll, Julien Kammer, Eric Lamaud, Benjamin Loubet, Erwan Personne, Patrick Stella

    Ozone is a potentially phyto-toxic air pollutant, which can cause leaf damage and drastically alter crop yields, causing serious economic losses around the world. The VULNOZ (VULNerability to OZone in Anthropised Ecosystems) project is a biology and modeling project that aims to understand how plants respond to the stress of high ozone concentrations, then use a set of models to (i) predict the impact of ozone on plant growth, (ii) represent ozone deposition fluxes to vegetation, and finally (iii) estimate the economic consequences of an increasing ozone background the future. In this work, as part of the VULNOZ project, an innovative representation of ozone deposition to vegetation was developed and implemented in the CHIMERE regional chemistry-transport model. This type of model calculates the average amount of ozone deposited on a parcel each hour, as well as the integrated amount of ozone deposited to the surface at the regional or country level. Our new approach was based on a refinement of the representation of crop types in the model and the use of empirical parameters specific to each crop category. The results obtained were compared with a conventional ozone deposition modeling approach, and evaluated against observations from several agricultural areas in France. They showed that a better representation of the distribution between stomatal and non-stomatal ozone fluxes was obtained in the empirical approach, and they allowed us to produce a new estimate of the total amount of ozone deposited on the subtypes of vegetation at the national level.

    更新日期:2018-01-06
  • Characteristics of inorganic aerosol formation over ammonia-poor and ammonia-rich areas in the Pearl River Delta region, China
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-05
    Shasha Yin, Zhijiong Huang, Junyu Zheng, Xiaobo Huang, Duohong Chen, Haobo Tan

    A well-evaluated Comprehensive Air quality Model with extensions (CAMx) was used to simulate concentrations of secondary inorganic aerosols in fine particulate matter (PM2.5) over Pearl River Delta (PRD) region during two separate months (April and October) in 2013. An indicator of adjusted gas ratio (AdjGR) was used to characterize PM chemistry under both NH3-poor (NP) and NH3-rich (NR) conditions as well as to identify their respective spatiotemporal patterns at different PM2.5 levels. The results were as follows: (1) Based on both observed molar ratio of [NH4+]/[SO42−] and modeled AdjGR, NR and NP condition exhibited diurnal, daily, and seasonal variations. (2) A larger area in PRD had NP conditions over the two months when pollution was apparent; this NP region tended to occur downwind of PRD in October and the central region of PRD in April, with high PM2.5 concentrations in both. (3) This wider NP distribution could be related to higher nitrogen oxidation ratio (NOR), with more NOx converting to nitrate. Under conditions of higher pollution, there were relative lower degree of sulfate neutralization (DSN) and particle neutralization ratio (PNR). This supports the claim that NH3 may not be fully neutralized by SO42−. (4) Modeled AdjGR displayed clear hourly variations, with the lowest levels occurring in the afternoon. Reducing NH3 emissions is not as efficient as NOx at increasing evening nitrate concentrations. (5) To mitigate PM2.5 pollution even further, a greater reduction of NH3 should be suggested in chemical regions transiting to NR condition when there are lower SO2 and NOx emissions.

    更新日期:2018-01-05
  • Characterizing and sourcing ambient PM2.5 over key emission regions in China III: Carbon isotope based source apportionment of black carbon
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-04
    Kuangyou Yu, Zhenyu Xing, Xiaofeng Huang, Junjun Deng, August Andersson, Wenzheng Fang, Örjan Gustafsson, Jiabin Zhou, Ke Du

    Regional haze over China has severe implications for air quality and regional climate. To effectively combat these effects the high uncertainties regarding the emissions from different sources needs to be reduced. In this paper, which is the third in a series on the sources of PM2.5 in pollution hotspot regions of China, we focus on the sources of black carbon aerosols (BC), using carbon isotope signatures. Four-season samples were collected at two key locations: Beijing-Tianjin-Hebei (BTH, part of Northern China plain), and the Pearl River Delta (PRD). We find that that fossil fuel combustion was the predominant source of BC in both BTH and PRD regions, accounting for 75 ± 5%. However, the contributions of what fossil fuel components were dominating differed significantly between BTH and PRD, and varied dramatically with seasons. Coal combustion is overall the all-important BC source in BTH, accounting for 46 ± 12% of the BC in BTH, with the maximum value (62%) found in winter. In contrast for the PRD region, liquid fossil fuel combustion (e.g., oil, diesel, and gasoline) is the dominant source of BC, with an annual mean value of 41 ± 15% and the maximum value of 55% found in winter. Region- and season-specific source apportionments are recommended to both accurately assess the climate impact of carbonaceous aerosol emissions and to effectively mitigate deteriorating air quality caused by carbonaceous aerosols.

    更新日期:2018-01-05
  • Impact of regional haze towards air quality in Malaysia: A review
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-04
    Mohd Talib Latif, Murnira Othman, Nurfathehah Idris, Liew Juneng, Ahmad Makmom Abdullah, Wan Portia Hamzah, Md Firoz Khan, Nik Meriam Nik Sulaiman, Jegalakshimi Jewaratnam, Nasrin Aghamohammadi, Mazrura Sahani, Chung Jing Xiang, Fatimah Ahamad, Norhaniza Amil, Mashitah Darus, Helena Varkkey, Fredolin Tangang, Abu Bakar Jaafar

    Haze is a common phenomenon afflicting Southeast Asia (SEA), including Malaysia, and has occurred almost every year within the last few decades. Haze is associated with high level of air pollutants; it reduces visibility and affects human health in the affected SEA countries. This manuscript aims to review the potential origin, chemical compositions, impacts and mitigation strategies of haze in Malaysia. “Slash and burn” agricultural activities, deforestation and oil palm plantations on peat areas, particularly in Sumatra and Kalimantan, Indonesia were identified as the contributing factors to high intensity combustions that results in transboundary haze in Malaysia. During the southwest monsoon (June to September), the equatorial SEA region experiences a dry season and thus an elevated number of fire events. The prevailing southerly and south-westerly winds allow the cross-boundary transportation of pollutants from the burning areas in Sumatra and Kalimantan in Indonesia, to Peninsular Malaysia and Malaysian Borneo, respectively. The dry periods caused by the El Niño - Southern Oscillation (ENSO) prolong the duration of poor air quality. The size range of particulate matter (PM) in haze samples indicates that haze is dominated by fine particles. Secondary inorganic aerosols (SIA, such as SO42- and NH4+) and organic substances (such as levoglucosan, LG) were the main composition of PM during haze episodes. Local vehicular emissions and industrial activities also contribute to the amount of pollutants and can introduce toxic material such as polyaromatic hydrocarbons (PAHs). Haze episodes have contributed to increasing hospital visits for treatments related to chronic obstructive pulmonary diseases, upper respiratory infections, asthma and rhinitis. Respiratory mortality increased 19% due to haze episodes. Children and senior citizens are more likely to suffer the health impacts of haze. The inpatient cost alone from haze episodes was estimated at around USD 91,000 per year in Malaysia. Almost all economic sectors also experienced losses, with the heaviest losses in the agriculture and tourism sectors. This review suggests several ways forward to reduce haze episodes in SEA and Malaysia. These include economic approaches, research collaborations and science-policy interface. Improving forecasting capabilities can help reduce response time to burning events and subsequently reduce its impacts. Lastly, commitment and involvement by individuals, government agencies, and the entrepreneurial private sectors are crucial to reduce biomass burning (BB) and haze episodes in SEA.

    更新日期:2018-01-05
  • Increases in wintertime PM2.5 sodium and chloride linked to snowfall and road salt application
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-04
    Katheryn R. Kolesar, Claire N. Mattson, Peter K. Peterson, Nathaniel W. May, Rashad K. Prendergast, Kerri A. Pratt
    更新日期:2018-01-05
  • Exploratory study of atmospheric methane enhancements derived from natural gas use in the Houston urban area
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-04
    Nancy P. Sanchez, Chuantao Zheng, Weilin Ye, Beata Czader, Daniel S. Cohan, Frank K. Tittel, Robert J. Griffin

    The extensive use of natural gas (NG) in urban areas for heating and cooking and as a vehicular fuel is associated with potentially significant emissions of methane (CH4) to the atmosphere. Methane, a potent greenhouse gas that influences the chemistry of the atmosphere, can be emitted from different sources including leakage from NG infrastructure, transportation activities, end-use uncombusted NG, landfills and livestock. Although significant CH4 leakage associated with aging local NG distribution systems in the U.S. has been reported, further investigation is required to study the role of this infrastructure component and other NG-related sources in atmospheric CH4 enhancements in urban centers. In this study, neighborhood-scale mobile-based monitoring of potential CH4 emissions associated with NG in the Greater Houston area (GHA) is reported. A novel dual-gas 3.337 μm interband cascade laser-based sensor system was developed and mobile-mode deployed for simultaneous CH4 and ethane (C2H6) monitoring during a period of over 14 days, corresponding to ∼ 90 h of effective data collection during summer 2016. The sampling campaign covered ∼250 exclusive road miles and was primarily concentrated on eight residential zones with distinct infrastructure age and NG usage levels. A moderate number of elevated CH4 concentration events (37 episodes) with mixing ratios not exceeding 3.60 ppmv and associated with atmospheric background enhancements below 1.21 ppmv were observed during the field campaign. Source discrimination analyses based on the covariance between CH4 and C2H6 levels indicated the predominance of thermogenic sources (e.g., NG) in the elevated CH4 concentration episodes. The volumetric fraction of C2H6 in the sources associated with the thermogenic CH4 spikes varied between 2.7 and 5.9%, concurring with the C2H6 content in NG distributed in the GHA. Isolated CH4 peak events with significantly higher C2H6 enhancements (∼11%) were observed at industrial areas and locations with high density of petroleum and gas pipelines in the GHA, indicating potential variability in Houston's thermogenic CH4 sources.

    更新日期:2018-01-05
  • Hygroscopic properties of atmospheric particles emitted during wintertime biomass burning episodes in Athens
    Atmos. Environ. (IF 3.629) Pub Date : 2018-01-04
    Magda Psichoudaki, Athanasios Nenes, Kalliopi Florou, Christos Kaltsonoudis, Spyros N. Pandis

    This study explores the Cloud Condensation Nuclei (CCN) activity of atmospheric particles during intense biomass burning periods in an urban environment. During a one-month campaign in the center of Athens, Greece, a CCN counter coupled with a Scanning Mobility Particle Sizer (SMPS) and a high resolution Aerosol Mass Spectrometer (HR-AMS) were used to measure the size-resolved CCN activity and composition of the atmospheric aerosols.During the day, the organic fraction of the particles was more than 50%, reaching almost 80% at night, when the fireplaces were used. Positive Matrix Factorization (PMF) analysis revealed 4 factors with biomass burning being the dominant source after 18:00 until the early morning. The CCN-based overall hygroscopicity parameter κ ranged from 0.15 to 0.25. During the night, when the biomass burning organic aerosol (bbOA) dominated, the hygroscopicity parameter for the mixed organic/inorganic particles was on average 0.16. The hygroscopicity of the biomass-burning organic particles was 0.09, while the corresponding average value for all organic particulate matter during the campaign was 0.12.

    更新日期:2018-01-05
  • The impact of urban canopy meteorological forcing on summer photochemistry
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-30
    Peter Huszár, Jan Karlický, Michal Belda, Tomáš Halenka, Petr Pišoft

    The regional climate model RegCM4.4, including the surface model CLM4.5, was offline coupled to the chemistry transport model CAMx version 6.30 in order to investigate the impact of the urban canopy induced meteorological changes on the longterm summer photochemistry over central Europe for the 2001–2005 period. First, the urban canopy impact on the meteorological conditions was calculated performing a reference experiment without urban landsurface considered and an experiment with urban surfaces modeled with the urban parameterization within the CLM4.5 model. In accordance with expectations, strong increases of urban surface temperatures (up to 2–3 K), decreases of wind speed (up to -1 ms−1) and increases of vertical turbulent diffusion coefficient (up to 60–70 m2s-1) were found. For the impact on chemistry, these three components were considered. Additionally, we accounted for the effect of temperature enhanced biogenic emission increase. Several experiments were performed by adding these effects one-by-one to the total impact: i.e., first, only the urban temperature impact was considered driving the chemistry model; secondly, the wind impact was added and so on. We found that the impact on biogenic emission account for minor changes in the concentrations of ozone (O3), oxides of nitrogen NOx = NO + NO2 and nitric acid (HNO3). On the other hand, the dominating component acting is the increased vertical mixing, resulting in up to 5 ppbv increase of urban ozone concentrations while causing -2 to -3 ppbv decreases and around 1 ppbv increases of NOx and HNO3 surface concentrations, respectively. The temperature impact alone results in reduction of ozone, increase in NO, decrease in NO2 and increases of HNO3. The wind impact leads, over urban areas, to ozone decreases, increases of NOx and a slight increase in HNO3. The overall impact is similar to the impact of increased vertical mixing alone. The Process Analysis (PA) technique implemented in CAMx was adopted to investigate the causes of the modeled impacts in more details. It showed that the main process contributing to the temperature impact on ozone is a dry-deposition enhancement, while the dominating process controlling the wind impact on ozone over cities is the advection reduction. In case of the impact of enhanced turbulence, PA suggests that ozone increases are, again as assumed, the result of increased downward vertical mixing supported by reduced chemical loss. Comparing the model concentrations with measurements over urban areas, a slight improvement of the model performance was achieved during afternoon hours if urban canopy forcing on chemistry via meteorology was accounted for. The study demonstrates that disregarding the urban canopy induced meteorological effects in air-quality oriented modeling studies can lead to erroneous results in the calculated species concentrations. However, it also shows that the individual components are not equally important: urban canopy induced turbulence effects dominate while the wind-speed and temperature related ones are of considerably smaller magnitude.

    更新日期:2017-12-31
  • Atmospheric ammonia measurements along the coastal lines of Southeastern China: Implications for inorganic nitrogen deposition to coastal waters
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-30
    Shui-Ping Wu, Lu-Hong Dai, Ya Wei, Heng Zhu, Yin-Ju Zhang, James J. Schwab, Chung-Shin Yuan
    更新日期:2017-12-31
  • Detection of nuclear testing from surface concentration measurements: Analysis of radioxenon from the February 2013 underground test in North Korea
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-28
    R.J. Kurzeja, R.L. Buckley, D.W. Werth, S.R. Chiswell

    A method is outlined and tested to detect low level nuclear or chemical sources from time series of concentration measurements. The method uses a mesoscale atmospheric model to simulate the concentration signature from a known or suspected source at a receptor which is then regressed successively against segments of the measurement series to create time series of metrics that measure the goodness of fit between the signatures and the measurement segments. The method was applied to radioxenon data from the Comprehensive Test Ban Treaty (CTBT) collection site in Ussuriysk, Russia (RN58) after the Democratic People's Republic of Korea (North Korea) underground nuclear test on February 12, 2013 near Punggye. The metrics were found to be a good screening tool to locate data segments with a strong likelihood of origin from Punggye, especially when multiplied together to a determine the joint probability. Metrics from RN58 were also used to find the probability that activity measured in February and April of 2013 originated from the Feb 12 test. A detailed analysis of an RN58 data segment from April 3/4, 2013 was also carried out for a grid of source locations around Punggye and identified Punggye as the most likely point of origin. Thus, the results support the strong possibility that radioxenon was emitted from the test site at various times in April and was detected intermittently at RN58, depending on the wind direction. The method does not locate unsuspected sources, but instead, evaluates the probability of a source at a specified location. However, it can be extended to include a set of suspected sources. Extension of the method to higher resolution data sets, arbitrary sampling, and time-varying sources is discussed along with a path to evaluate uncertainty in the calculated probabilities.

    更新日期:2017-12-31
  • Observed and predicted sensitivities of extreme surface ozone to meteorological drivers in three US cities
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-28
    Miranda J. Fix, Daniel Cooley, Alma Hodzic, Eric Gilleland, Brook T. Russell, William C. Porter, Gabriele G. Pfister

    We conduct a case study of observed and simulated maximum daily 8-h average (MDA8) ozone (O3) in three US cities for summers during 1996–2005. The purpose of this study is to evaluate the ability of a high resolution atmospheric chemistry model to reproduce observed relationships between meteorology and high or extreme O3. We employ regional coupled chemistry-transport model simulations to make three types of comparisons between simulated and observational data, comparing (1) tails of the O3 response variable, (2) distributions of meteorological predictor variables, and (3) sensitivities of high and extreme O3 to meteorological predictors. This last comparison is made using two methods: quantile regression, for the 0.95 quantile of O3, and tail dependence optimization, which is used to investigate even higher O3 extremes. Across all three locations, we find substantial differences between simulations and observational data in both meteorology and meteorological sensitivities of high and extreme O3.

    更新日期:2017-12-31
  • Exposure- and flux-based assessment of ozone risk to sugarcane plants
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-27
    Bárbara Baêsso Moura, Yasutomo Hoshika, Rafael Vasconcelos Ribeiro, Elena Paoletti

    Ozone (O3) is a toxic oxidative air pollutant, with significant detrimental effects on crops. Sugarcane (Saccharum spp.) is an important crop with no O3 risk assessment performed so far. This study aimed to assess O3 risk to sugarcane plants by using exposure-based indices (AOT40 and W126) based on O3 concentrations in the air, and the flux-based index (PODy, where y is a threshold of uptake) that considers leaf O3 uptake and the influence of environmental conditions on stomatal conductance (gsto). Two sugarcane genotypes (IACSP94-2094 and IACSP95-5000) were subjected to a 90-day Free-Air Controlled Experiment (FACE) exposure at three levels of O3 concentrations: ambient (Amb); Amb x1.2; and Amb x1.4. Total above-ground biomass (AGB), stalk biomass (SB) and leaf biomass (LB) were evaluated and the potential biomass production in a clean air was estimated by assuming a theoretical clean atmosphere at 10 ppb as 24 h O3 average. The Jarvis-type multiplicative algorithm was used to parametrize gsto including environmental factors i.e. air temperature, light intensity, air vapor pressure deficit, and minimum night-time temperature. Ozone exposure caused a negative impact on AGB, SB and LB. The O3 sensitivity of sugarcane may be related to its high gsto (∼535 mmol H2O m−2 s−1). As sugarcane is adapted to hot climate conditions, gsto was restricted when the current minimum air temperature (Tmin) was below ∼14 °C and the minimum night-time air temperature of the previous day (Tnmin) was below ∼7.5 °C. The flux-based index (PODy) performed better than the exposure-based indices in estimating O3 effect on biomass losses. We recommend a y threshold of 2 nmol m−2 s−1 to incorporate O3 effects on both AGB and SB and 1 nmol m−2 s−1 on LB. In order not to exceed 4% reduction in the growth of these two sugarcane genotypes, we recommend the following critical levels: 1.09 and 1.04 mmol m−2 POD2 for AGB, 0.91 and 0.96 mmol m−2 POD2 for SB, and 3.00 and 2.36 mmol m−2 POD1 for LB of IACSP95-5000 and IACSP94-2094, respectively.

    更新日期:2017-12-31
  • First results of tall tower based nitrous oxide flux monitoring over an agricultural region in Central Europe
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-27
    László Haszpra, Dóra Hidy, Tímea Taligás, Zoltán Barcza

    Nitrous oxide is one of the atmospheric greenhouse gases whose amount is significantly influenced by human activity. Its major anthropogenic sources are the agricultural soils but the emission is known only with large uncertainty yet. The paper presents a tall tower based measuring system installed in Hungary, which is designed for the long-term monitoring of nitrous oxide emission of a regionally typical composition of agricultural fields by means of eddy covariance technique. Due to the careful calibration of the gas analyzer applied the measuring system is also suitable for the recording of the atmospheric concentration of nitrous oxide on the globally compatible scale (WMO X2006A). The paper reports the results of the first two years of the monitoring program, which is the first of its kind in Central Europe. For the period of July 2015–June 2017 the concentration measurements indicate an increasing trend of 0.91 nmol mol−1 year−1 with an average concentration of 330.64 nmol mol−1. During the two years of the project, the monitoring system recorded a total of 441 ± 195 mg N2O-N m−2 nitrous oxide emission with late spring/early summer maximum. The measurements also revealed the episodic nature of the emission typically triggered by major precipitation events.

    更新日期:2017-12-27
  • Identification and semi-quantification of biogenic organic nitrates in ambient particulate matters by UHPLC/ESI-MS
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-27
    Rui Li, Xinfeng Wang, Rongrong Gu, Chunying Lu, Fanping Zhu, Likun Xue, Huijun Xie, Lin Du, Jianmin Chen, Wenxing Wang

    Particulate biogenic organic nitrates (PBONs) are important components of secondary organic aerosols and play an important role in the tropospheric atmosphere chemistry. However, the concentrations and the chemistry of PBONs remain poorly understood due to the lack of accurate measurement techniques on specific organic nitrates. In this study, ultra high performance liquid chromatography/electrospray mass spectrometry was applied in detection of individual PBONs in ambient atmosphere. Total five kinds of PBONs were identified in PM2.5 samples collected in urban Ji'nan in spring according to characteristic fragments of NO2, NO3, HNO3, CO2, and H2O, including monoterpene hydroxyl nitrate (MW = 215, MHN215), pinene keto nitrate (MW = 229, PKN229), limonene di-keto nitrate (MW = 247, LDKN247), oleic acid keto nitrate (MW = 359, OAKN359), and oleic acid hydroxyl nitrate (MW = 361, OAHN361). Among them, three kinds of PBONs originated from biogenic volatile organic compounds of pinene and limonene and two kinds of PBONs came from chemical conversion of oleic acid. The concentrations of these PBONs were roughly quantified with surrogate standards of (1R,2R,5R)-(+)-2-hydroxy-3-pinanone and ricinoleic acid. The average concentrations of MHN215, PKN229, LDKN247, OAKN359, and OAHN361 were 111.6 ± 23.0, 93.1 ± 49.6, 55.3 ± 7.4, 23.4 ± 14.5, 36.8 ± 18.3 ng m−3, respectively. The total concentration of these PBONs was 325.4 ± 116.7 ng m−3, contributing to 1.64 ± 0.34‰ of PM2.5.

    更新日期:2017-12-27
  • Tracer element for indoor PM2.5 in China migrated from outdoor
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-26
    Wenjing Ji, Hongyu Li, Bin Zhao, Furong Deng
    更新日期:2017-12-27
  • Emissions of volatile organic compounds from maize residue open burning in the northern region of Thailand
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-26
    Duanpen Sirithian, Sarawut Thepanondh, Melanie L. Sattler, Wanna Laowagul

    Emission factors for speciated volatile organic compounds (VOCs) from maize residue burning were determined in this study based on chamber experiments. Thirty-six VOC species were identified by Gas Chromatography/Mass Spectrometer (GC/MS). They were classified into six groups, including alkanes, alkenes, oxygenated VOCs, halogenated VOCs, aromatics and other. The emission factor for total VOCs was estimated as about 148 mg kg−1 dry mass burned. About 68.4% of the compounds were aromatics. Field samplings of maize residues were conducted to acquire the information of fuel characteristics including fuel loading, fraction of maize residues that were actually burned as well as proximate and elemental analysis of maize residues. The emission factors were then applied to estimate speciated VOC emissions from maize residue open burning at the provincial level in the upper-northern region of Thailand for the year 2014. Total burned area of maize covered an area of about 500,000 ha which was about 4.7% of the total area of upper-northern region of the country. It was found that total VOC emissions released during the burning season (January–April) was about 79.4 tons. Ethylbenzene, m,p-xylene, 1,2,4-trimethylbenzene, acetaldehyde and o-xylene were the major contributors, accounting for more than 65% of total speciated VOC emissions.

    更新日期:2017-12-27
  • Secondary inorganic aerosols formation during haze episodes at an urban site in Beijing, China
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-25
    Rui Zhang, Xuesong Sun, Yuhu Huang, Aijun Shi, Jing Yan, Teng Nie, Xiao Yan, Xuan Li

    Severe PM2.5 pollution was observed frequently in Beijing. We conducted highly time-resolved measurements of inorganic ions associated with PM2.5 at an urban site in Beijing from 10 February to 19 March, 2015. The average PM2.5 mass concentrations during the six haze episodes ranged from 113.0 μg/m3 to 182.6 μg/m3, which were more than 8 times higher than those observed in clean periods. The secondary inorganic species (NH4+, SO42− and NO3−) in PM2.5 sharply increased during the haze episodes, indicating more extensive formation of SO42− and NO3−. The sulfur oxidation ratios (SOR) and the nitrogen oxidation ratios (NOR) in haze episodes were higher than those in clean periods, which indicated that secondary transformation in haze episodes was more significant than those in clean periods. No correlations between SOR and the oxidants (O3 and HONO) and the temperature were found, whereas a high correlation between SOR and relative humidity (RH) was found in haze episodes, which implied that sulfate was mainly produced by the aqueous-phase oxidation of SO2 rather than the gas-phase conversion of SO2 to sulfate. The conversion of SO2 to SO42− was observed to be sensitive to changes in RH. Furthermore, the SOR sharply increased at RH > 60% with the highest value of 0.88 at RH around 80% during complicated pollution. NO2 played an important role in the rapid sulfate formation with high RH and NH3 neutralization conditions in haze episodes in Beijing. The impact of RH was less apparent for nitrate than for sulfate. Nitrate was found to be produced mainly by photochemical and heterogeneous reactions, while heterogeneous reactions had a greater influence on NOR at nighttime. The NO3−/SO42− ratio indicated that mobile sources contributed more to the formation of PM2.5 than stationary sources. The result suggested the need for control of vehicle emissions to reduce the high levels of NOx and nitrate and the severe PM2.5 pollution in Beijing.

    更新日期:2017-12-27
  • 更新日期:2017-12-22
  • 更新日期:2017-12-22
  • Analysis of reaction products formed in the gas phase reaction of E,E-2,4-hexadienal with atmospheric oxidants: Reaction mechanisms and atmospheric implications
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-21
    I. Colmenar, P. Martin, B. Cabañas, S. Salgado, E. Martinez

    An analysis of reaction products for the reaction of E,E-2,4-hexadienal with chlorine atoms (Cl) and OH and NO3 radicals has been carried out at the first time with the aim of obtaining a better understanding of the tropospheric reactivity of α,β-unsaturated carbonyl compounds. Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography-Mass Spectrometry with a Time of Flight detector (GC-TOFMS) were used to carry out the qualitative and/or quantitative analyses. Reaction products in gas and particulate phase were observed from the reactions of E,E-2,4- hexadienal with all oxidants. E/Z-Butenedial and maleic anhydride were the main products identified in gas phase. E-butenedial calculated molar yield ranging from 4 to 10%. A significant amount of multifunctional compounds (chloro and hydroxy carbonyls) was identified. These compounds could be formed in particulate phase explaining the ∼90% of unaccounted carbon in gas phase. The reaction with Cl atoms in the presence of NOx with a long reaction time gave. Peroxy acetyl nitrate (PAN) as an additional product, which is known for being an important specie in the generation of the photochemical smog. Nitrated compounds were the major organic products from the reaction with the NO3 radical. Based on the identified products, the reaction mechanisms have been proposed. In these mechanisms a double bond addition of the atmospheric oxidant at C4/C5 of E,E-2,4-hexadienal is the first step for tropospheric degradation.

    更新日期:2017-12-22
  • Spatial variations in soil and plant nitrogen levels caused by ammonia deposition near a cattle feedlot
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-21
    Jianlin Shen, Deli Chen, Mei Bai, Jianlei Sun, Shu Kee Lam, Arvin Mosier, Xinliang Liu, Yong Li

    Cattle feedlots are significant ammonia (NH3) emission sources, and cause high NH3 deposition. This study was conducted to investigate the responses of soil mineral nitrogen (N), percent cover of plant species, leaf N content, and leaf δ15N to NH3 deposition around a 17,500-head cattle feedlot in Victoria, Australia. Soil samples were collected in May 2015 at 100-m intervals along eight downwind transects, and plant samples were collected in June 2015 from five sites at 50- to 300-m intervals along a grassland transect within 1 km downwind of the feedlot. NH3 deposition was also monitored at five sites within 1 km downwind of the feedlot. The estimated NH3-N deposition rate ranged from 2.9 kg N ha−1 yr−1 at 1 km from the feedlot to 203 kg N ha−1 yr−1 at 100 m from the feedlot. The soil mineral N content was high (22–98 mg kg−1, mainly nitrate), significantly decreased with increasing distance from the feedlot, and significantly increased with increasing NH3-N deposition. With increasing NH3-N deposition, the percent cover of the herb species Cymbonotus lawsonianus increased significantly, but that of the grass species Microlaena stipoides decreased significantly. The leaf total N contents of the grass and herb species were high (>4%), and were linearly, positively correlated with the NH3-N deposition rate. Leaf δ15N values were linearly, negatively correlated with the N deposition rate. These results indicate that the leaf N contents and δ15N values of C. lawsonianus and M. stipoides may be bioindicators of N deposition.

    更新日期:2017-12-22
  • Black carbon emissions from biomass and coal in rural China
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-21
    Weishi Zhang, Zifeng Lu, Yuan Xu, Can Wang, Yefu Gu, Hui Xu, David G. Streets

    Residential solid fuel combustion makes a major contribution to black carbon (BC) emissions in China. A new estimation of BC emissions from rural solid biomass and coal consumption has been derived from field survey data. The following new contributions are made: (1) emission factors are collected and reviewed; (2) household energy data are collected from field survey data and from the literature; (3) a new extrapolation method is developed to extend the field survey data to other locations; (4) the ownership and usage of two stove types are estimated and considered in the emission calculations; and (5) uncertainties associated with the estimation results are quantified. It is shown that rural households with higher income will consume less biomass but more coal. Agricultural acreage and temperature also significantly influence the amount of solid fuel consumed in rural areas. It is estimated that 640 ± 245 Gg BC/y were emitted to the atmosphere due to residential solid fuel consumption in rural China in 2014. Emissions of BC from straw, wood, and coal contributed 42 ± 13%, 36 ± 15%, and 22 ± 10% of the total, respectively. We show that effective BC mitigation (a reduction of 47%) could be obtained through widespread introduction of improved stoves in rural households.

    更新日期:2017-12-22
  • Spatial and temporal variation in sources of atmospheric nitrogen deposition in the Rocky Mountains using Nitrogen isotopes
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-20
    Leora Nanus, Donald H. Campbell, Christopher M.B. Lehmann, M. Alisa Mast

    Variation in source areas and source types of atmospheric nitrogen (N) deposition to high-elevation ecosystems in the Rocky Mountains were evaluated using spatially and temporally distributed N isotope data from atmospheric deposition networks for 1995-2016. This unique dataset links N in wet deposition and snowpack to mobile and stationary emissions sources, and enhances understanding of the impacts of anthropogenic activities and environmental policies that mitigate effects of accelerated N cycling across the Rocky Mountain region. δ15N−NO3− at 50 U.S. Geological Survey Rocky Mountain Snowpack (Snowpack) sites ranged from −3.3‰ to +6.5‰, with a mean value of +1.4‰. At 15 National Atmospheric Deposition Program (NADP)/National Trends Network wet deposition (NADP Wetfall) sites, summer δ15N−NO3− is significantly lower ranging from −7.6‰ to −1.3‰ while winter δ15N−NO3− ranges from −2.6‰ to +5.5‰, with a mean value of +0.7‰ during the cool season. The strong seasonal difference in NADP Wetfall δ15N−NO3− is due in part to variation in the proportion of N originating from source regions at different times of the year due to seasonal changes in weather patterns. Snowpack NO3− and δ15N−NO3− are significantly related to NADP Wetfall (fall and winter) suggesting that bulk snowpack samples provide a reliable estimate at high elevations. Spatial trends show higher NO3− concentrations and δ15N−NO3− in the Southern Rocky Mountains located near larger anthropogenic N emission sources compared to the Northern Rocky Mountains. NADP Wetfall δ15N−NH4+ ranged from −10‰ to 0‰, with no observed spatial pattern. However, the lowest δ15N−NH4+(−9‰), and the highest NH4+ concentration (35 μeq/L) were observed at a Utah site dominated by local agricultural activities, whereas the higher δ15N−NH4+ observed in Colorado and Wyoming are likely due to mixed sources, including fossil fuel combustion and agricultural sources. These findings show spatial and seasonal variation in N isotope data that reflect differences in sources of anthropogenic N deposition to high-elevation ecosystems and have important implications for environmental policy across the Rocky Mountain region.

    更新日期:2017-12-21
  • Biogenic volatile organic compound emissions from senescent maize leaves and a comparison with other leaf developmental stages
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-19
    A. Mozaffar, N. Schoon, A. Bachy, A. Digrado, B. Heinesch, M. Aubinet, M.-L. Fauconnier, P. Delaplace, P. du Jardin, C. Amelynck
    更新日期:2017-12-19
  • Genotoxic effects of daily personal exposure to particle mass and number concentrations on buccal cells
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-19
    Daniela S. de Almeida, Silvano César da Costa, Marcos Ribeiro, Camila A.B. Moreira, Alexandra Beal, Rafaela Squizzato, Anderson Paulo Rudke, Sameh Adib Abou Rafee, Jorge A. Martins, Graciana Freitas Palioto, Prashant Kumar, Leila D. Martins
    更新日期:2017-12-19
  • 更新日期:2017-12-19
  • Assessment of trace metal levels in size-resolved particulate matter in the area of Leipzig
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-19
    Khanneh Wadinga Fomba, Dominik van Pinxteren, Konrad Müller, Gerald Spindler, Hartmut Herrmann

    Size-resolved trace metal concentrations at four sites in Leipzig (Germany) and its surrounding were assessed between the winter of 2013 and the summer of 2015. The measurements were performed in parallel at; traffic dominated (Leipzig – Mitte, LMI), traffic and residential dominated (Eisenbahnstrasse, EIB), urban background (TROPOS, TRO) and regional background (Melpitz, MEL) sites. In total, 19 trace metals, i.e. K, Ca, Ti, Mn, Fe, Cu, Zn, As, Se, Ba, V, Pb, Ni, Cr, Sr, Sn, Sb, Co and Rb were analysed using total reflection x-ray fluorescence (TXRF). The major metals were Fe, K and Ca with concentrations ranging between; 31–440 ng/m3, 42–153 ng/m3 and 24–322 ng/m3, respectively, while the trace metals with the lowest concentrations were Co, Rb and Se with concentrations of; < 0.3 ng/m3, <0.5 ng/m3 and 0.5–0.7 ng/m3, respectively. PM10 trace metal concentrations during easterly air mass inflow especially at the background sites were in average 70% higher in the winter and 30% higher in the summer in comparison to westerly air mass inflow. Traffic at LMI contributed to about 75% of Cr, Ba, Cu, Sb, Sn, Ca, Co, Mn, Fe and Ti concentrations while regional activities contributed to more than 70% of K, Rb, Pb, Se, As and V concentrations. Traffic dominated trace metals were often observed in the coarse mode while the regional background dominated trace metals were often observed in the fine mode. Trace metal sources were related to crustal matter and road dust re-suspension for metals such as Ca, Fe, Co, Sr, and Ti, brake and tire wear (Cu, Sb, Ba, Fe, Zn, Pb), biomass burning (K, Rb), oil and coal combustion (V, Zn, As, Pb). Crustal matter contributed 5–12% in winter and 8–19% in summer of the PM10 mass. Using Cu and Zn as markers for brake and tire wear, respectively, the estimated brake and tire wear contributions to the PM10 mass were 0.1–0.8% and 1.7–2.9%, respectively. The higher contributions were observed at the traffic sites while the lower contributions were observed at the regional background site. In total, non-exhaust emissions could account for about 10–22% of the PM10 mass in the summer and about 7–15% of the PM10 mass in the winter.

    更新日期:2017-12-19
  • Evaluation of nitrous oxide as a substitute for sulfur hexafluoride to reduce global warming impacts of ANSI/HPS N13.1 gaseous uniformity testing
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-16
    Xiao-Ying Yu, J. Matthew Barnett, Brett G. Amidan, Kurtis P. Recknagle, Julia E. Flaherty, Ernest J. Antonio, John A. Glissmeyer
    更新日期:2017-12-18
  • Emission factors of greenhouse gases from layer and broiler barns in Cameroon
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-16
    N.M. Ngwabie, A.N. Acobta, V.E. Manga, A.C. VanderZaag

    Limited information is available in the literature on greenhouse gas (GHG) quantification from livestock production systems in Africa. Therefore, this project was carried out to generate baseline emission factors of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) from broiler and layer barns with building design typical of Cameroon. Emissions were measured from two broiler barns during the entire production cycles and a layer barn for a limited period using flux chambers. Methane emission factors from the broiler barns with mud and cement floors were 0.96 ± 1.04 and 0.36 ± 0.17 mg bird−1 hr−1 respectively, and 0.76 ± 0.56 mg bird−1 hr−1 from the layer barn with cement floor. Nitrous oxide emission from the broiler barns with mud and cement floors were 12.94 ± 10.11 and 1.68 ± 1.02 mg bird−1 hr−1 respectively, and 0.21 ± 0.28 mg bird−1 hr−1 from the layer barn. Carbon dioxide emission factors from the broiler barns with mud and cement floors were 9327 ± 3508 and 25526 ± 6904 mg bird−1 hr−1 respectively, and 8942 ± 36756 mg bird−1 hr−1 from the layer barn. When scaled per livestock unit (LU), where 1 LU is 500 kg bird weight, CH4 emissions were 0.16 ± 0.17 and 0.06 ± 0.03 g LU−1 hr−1 from the broiler barns, and 0.19 ± 0.14 g LU−1 hr−1 from the layer barn. Nitrous oxide emissions were 2.16 ± 1.69 and 0.28 ± 0.17 g LU−1 hr−1 from the broiler barns, and 0.05 ± 0.07 g LU−1 hr−1 from the layer barn. Broilers reared in management systems with wood shavings on mud floor had relatively high CH4 and N2O emissions compared to broilers on wood shavings and cement floor, with the contrary observed for CO2. The emissions N2O were significantly higher from broiler barns compared to layer barns. Emissions were higher in the mornings compared to later periods of the day. Given the observed results, GHG emission mitigation strategies need to be customised for each building design and management system.

    更新日期:2017-12-16
  • Comparison of two different dust emission mechanisms over the Horqin Sandy Land area: Aerosols contribution and size distributions
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-15
    Tingting Ju, Xiaolan Li, Hongsheng Zhang, Xuhui Cai, Yu Song

    Dust aerosols (PM10) P M 10 ) emission fluxes due to convective turbulent dust emissions (CTDE) and saltation-bombardment and/or aggregation-disintegration dust emissions (SADE) events were comparatively studied using the data obtained from the Naiman station over the Horqin Sandy Land area in Inner Mongolia, China from 2011 to 2015. The annual cumulative dust fluxes released by CTDE events was about one third of that by SADE events, with the order of 103∼104 μg m−2 s−1. The particle size distributions (PSDs) with diameter between 0.1 and 20 μm μ m during CTDE and SADE events over the Horqin Sandy Land area were simulated based on the fragmentation theory, respectively. The results indicated that an improved equation based on fragmentation theory could be applied to describe the PSD over the Horqin site and that was more applicable to SADE which may be because the scale-invariant fragmentation theory mainly explains the size distributions of free dust particles on the surface, which differs from the size distributions of suspend airborne dust. The number-related mean aerosol diameters (DN D N ) barely varied under different friction velocity (u∗ u ∗ ) for SADE events, while the volume-related mean aerosol diameters (DV D V ) changed distinctly with the change of u∗ u ∗ . For CTDE events, the DN D N and DV D V had no obvious relationship with the change of u∗ u ∗ because the dominating influence factor during CTDE event was thermal convection rather than u∗ u ∗ . The mass-related PSDs usually exhibited a peak between View the MathML source 0.45 a n d 0.70 μ m during SADE events, while for CTDE events there was a wide peak in the range of View the MathML source 0.10 ∼ 0.70 μ m . The results suggest that DN D N should be not be recommended as an individual parameter to describe the PSDs. The mass-related PSDs can effectively distinguish the SADE and CTDE events.

    更新日期:2017-12-16
  • Fine-scale application of WRF-CAM5 during a dust storm episode over East Asia: Sensitivity to grid resolutions and aerosol activation parameterizations
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-15
    Kai Wang, Yang Zhang, Xin Zhang, Jiwen Fan, L. Ruby Leung, Bo Zheng, Qiang Zhang, Kebin He

    An advanced online-coupled meteorology and chemistry model WRF-CAM5 has been applied to East Asia using triple-nested domains at different grid resolutions (i.e., 36-, 12-, and 4-km) to simulate a severe dust storm period in spring 2010. Analyses are performed to evaluate the model performance and investigate model sensitivity to different horizontal grid sizes and aerosol activation parameterizations and to examine aerosol-cloud interactions and their impacts on the air quality. A comprehensive model evaluation of the baseline simulations using the default Abdul-Razzak and Ghan (AG) aerosol activation scheme shows that the model can well predict major meteorological variables such as 2-m temperature (T2), water vapor mixing ratio (Q2), 10-m wind speed (WS10) and wind direction (WD10), and shortwave and longwave radiation across different resolutions with domain-average normalized mean biases typically within ±15%. The baseline simulations also show moderate biases for precipitation and moderate-to-large underpredictions for other major variables associated with aerosol-cloud interactions such as cloud droplet number concentration (CDNC), cloud optical thickness (COT), and cloud liquid water path (LWP) due to uncertainties or limitations in the aerosol-cloud treatments. The model performance is sensitive to grid resolutions, especially for surface meteorological variables such as T2, Q2, WS10, and WD10, with the performance generally improving at finer grid resolutions for those variables. Comparison of the sensitivity simulations with an alternative (i.e., the Fountoukis and Nenes (FN) series scheme) and the default (i.e., AG scheme) aerosol activation scheme shows that the former predicts larger values for cloud variables such as CDNC and COT across all grid resolutions and improves the overall domain-average model performance for many cloud/radiation variables and precipitation. Sensitivity simulations using the FN series scheme also have large impacts on radiations, T2, precipitation, and air quality (e.g., decreasing O3) through complex aerosol-radiation-cloud-chemistry feedbacks. The inclusion of adsorptive activation of dust particles in the FN series scheme has similar impacts on the meteorology and air quality but to lesser extent as compared to differences between the FN series and AG schemes. Compared to the overall differences between the FN series and AG schemes, impacts of adsorptive activation of dust particles can contribute significantly to the increase of total CDNC (∼45%) during dust storm events and indicate their importance in modulating regional climate over East Asia.

    更新日期:2017-12-15
  • Analysis of source regions and meteorological factors for the variability of spring PM10 concentrations in Seoul, Korea
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-14
    Jangho Lee, Kwang-Yul Kim

    CSEOF analysis is applied for the springtime (March, April, May) daily PM10 concentrations measured at 23 Ministry of Environment stations in Seoul, Korea for the period of 2003–2012. Six meteorological variables at 12 pressure levels are also acquired from the ERA Interim reanalysis datasets. CSEOF analysis is conducted for each meteorological variable over East Asia. Regression analysis is conducted in CSEOF space between the PM10 concentrations and individual meteorological variables to identify associated atmospheric conditions for each CSEOF mode. By adding the regressed loading vectors with the mean meteorological fields, the daily atmospheric conditions are obtained for the first five CSEOF modes. Then, HYSPLIT model is run with the atmospheric conditions for each CSEOF mode in order to back trace the air parcels and dust reaching Seoul. The K-means clustering algorithm is applied to identify major source regions for each CSEOF mode of the PM10 concentrations in Seoul. Three main source regions identified based on the mean fields are: (1) northern Taklamakan Desert (NTD), (2) Gobi Desert and (GD), and (3) East China industrial area (ECI). The main source regions for the mean meteorological fields are consistent with those of previous study; 41% of the source locations are located in GD followed by ECI (37%) and NTD (21%). Back trajectory calculations based on CSEOF analysis of meteorological variables identify distinct source characteristics associated with each CSEOF mode and greatly facilitate the interpretation of the PM10 variability in Seoul in terms of transportation route and meteorological conditions including the source area.

    更新日期:2017-12-15
  • Characterising fifteen years of continuous atmospheric radon activity observations at Cape Point (South Africa)
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-14
    R. Botha, C. Labuschagne, A.G. Williams, G. Bosman, E.-G. Brunke, A. Rossouw, R. Lindsay

    This paper describes and discusses fifteen years (1999–2013) of continuous hourly atmospheric radon (222Rn) monitoring at the coastal low-altitude Southern Hemisphere Cape Point Station in South Africa. A strong seasonal cycle is evident in the observed radon concentrations, with maxima during the winter months, when air masses arriving at the Cape Point station from over the African continental surface are more frequently observed, and minima during the summer months, when an oceanic fetch is predominant. An atmospheric mean radon activity concentration of 676 ± 2 mBq/m3 is found over the 15-year record, having a strongly skewed distribution that exhibits a large number of events falling into a compact range of low values (corresponding to oceanic air masses), and a smaller number of events with high radon values spread over a wide range (corresponding to continental air masses). The mean radon concentration from continental air masses (1 004 ± 6 mBq/m3) is about two times higher compared to oceanic air masses (479 ± 3 mBq/m3). The number of atmospheric radon events observed is strongly dependent on the wind direction. A power spectral Fast Fourier Transform analysis of the 15-year radon time series reveals prominent peaks at semi-diurnal, diurnal and annual time scales. Two inter-annual radon periodicities have been established, the diurnal 0.98 ± 0.04 day−1 and half-diurnal 2.07 ± 0.15 day−1. The annual peak reflects major seasonal changes in the patterns of offshore versus onshore flow associated with regional/hemispheric circulation patterns, whereas the diurnal and semi-diurnal peaks together reflect the influence of local nocturnal radon build-up over land, and the interplay between mesoscale sea/land breezes. The winter-time diurnal radon concentration had a significant decrease of about 200 mBq/m3 (17%) while the summer-time diurnal radon concentration revealed nearly no changes. A slow decline in the higher radon percentiles (75th and 95th) for the winter and spring seasons is found over the 15-year data set, with most of the change occurring in the first 9 years (1999–2007). This observed inter-annual decline appears to be associated with changes in the frequency of air masses having originated from over the African continental surfaces, and no significant trend is found in the lower radon percentiles associated with oceanic air masses. The general decrease of atmospheric radon associated with continental air-masses at Cape Point could be attributed to changing meteorological conditions, possibly driven by climate change.

    更新日期:2017-12-15
  • Contribution of microenvironments to personal exposures to PM10 and PM2.5 in summer and winter
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-14
    Yunhyung Hwang, Kiyoung Lee

    Personal exposure to particulate matter (PM) can be affected by time–activity patterns and microenvironmental concentrations. Particle size is closely associated with potential health problems, where smaller particles have greater effects on health. We investigated the effects of time–activity patterns on personal exposure and the contribution of the microenvironment to personal exposure to PM with maximal diameters of 10 μm and 2.5 μm (PM10 and PM2.5, respectively) in summer and winter. Technicians carried a nephelometer to detect various sizes of PM while engaging in one of nine scripted time–location–activity patterns. The scripted activities were based on the time–activity patterns of nine groups of inhabitants of Seoul, Korea. The monitoring was repeated in summer and winter to assess seasonal variation. The differences of personal exposures to PM10 and PM2.5 in summer and winter were not significant. The greatest PM concentrations occurred in restaurants. The PM2.5/PM10 ratios were varied from 0.35 at schools to 0.92 at stores. In both seasons, the residential indoor microenvironment was the largest contributor to personal PM exposure. The other major contributors were restaurants, offices, schools, buses, and walking, although their contributions differed by season and particle size. The different microenvironmental contributions among the activity pattern groups suggest that personal exposure significantly differs according to activity pattern.

    更新日期:2017-12-14
  • Evaluation of active sampling strategies for the determination of 1,3-butadiene in air
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-14
    Laura Vallecillos, Alba Maceira, Rosa Maria Marcé, Francesc Borrull
    更新日期:2017-12-14
  • Methanol exchange dynamics between a temperate cropland soil and the atmosphere
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-13
    A. Bachy, M. Aubinet, C. Amelynck, N. Schoon, B. Bodson, C. Moureaux, P. Delaplace, A. De Ligne, B. Heinesch
    更新日期:2017-12-14
  • Annual methane and nitrous oxide emissions from rice paddies and inland fish aquaculture wetlands in southeast China
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-12
    Shuang Wu, Zhiqiang Hu, Tao Hu, Jie Chen, Kai Yu, Jianwen Zou, Shuwei Liu
    更新日期:2017-12-14
  • Light attenuation versus evolved carbon (AVEC) – A new way to look at elemental and organic carbon analysis
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-12
    E.M.G. Nicolosi, P. Quincey, A. Font, G.W. Fuller
    更新日期:2017-12-14
  • Cloud condensation nuclei activity and hygroscopicity of fresh and aged cooking organic aerosol
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-08
    Yanwei Li, Antonios Tasoglou, Aikaterini Liangou, Kerrigan P. Cain, Leif Jahn, Peishi Gu, Evangelia Kostenidou, Spyros N. Pandis

    Cooking organic aerosol (COA) is potentially a significant fraction of organic particulate matter in urban areas. COA chemical aging experiments, using aerosol produced by grilling hamburgers, took place in a smog chamber in the presence of UV light or excess ozone. The water solubility distributions, cloud condensation nuclei (CCN) activity, and corresponding hygroscopicity of fresh and aged COA were measured. The average mobility equivalent activation diameter of the fresh particles at 0.4% supersaturation ranged from 87 to 126 nm and decreased for aged particles, ranging from 65 to 88 nm. Most of the fresh COA had water solubility less than 0.1 g L−1, even though the corresponding particles were quite CCN active. After aging the COA fraction with water solubility greater than 0.1 g L−1 increased more than 2 times. Using the extended Köhler theory for multiple partially soluble components in order to predict the measured activation diameters, the COA solubility distribution alone could not explain the CCN activity. Surface tensions less than 30 dyn cm−1 were required to explain the measured activation diameters. In addition, COA particles appear to not be spherical, which can introduce uncertainties into the corresponding calculations.

    更新日期:2017-12-14
  • Use of cameras for monitoring visibility impairment
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-08
    William Malm, Scott Cismoski, Anthony Prenni, Melanie Peters

    Webcams and automated, color photography cameras have been routinely operated in many U.S. national parks and other federal lands as far back as 1998, with a general goal of meeting interpretive needs within the public lands system and communicating effects of haze on scenic vistas to the general public, policy makers, and scientists. Additionally, it would be desirable to extract quantifiable information from these images to document how visibility conditions change over time and space and to further reflect the effects of haze on a scene, in the form of atmospheric extinction, independent of changing lighting conditions due to time of day, year, or cloud cover. Many studies have demonstrated a link between image indexes and visual range or extinction in urban settings where visibility is significantly degraded and where scenes tend to be gray and devoid of color. In relatively clean, clear atmospheric conditions, clouds and lighting conditions can sometimes affect the image radiance field as much or more than the effects of haze. In addition, over the course of many years, cameras have been replaced many times as technology improved or older systems wore out, and therefore camera image pixel density has changed dramatically. It is shown that gradient operators are very sensitive to image resolution while contrast indexes are not. Furthermore, temporal averaging and time of day restrictions allow for developing quantitative relationships between atmospheric extinction and contrast-type indexes even when image resolution has varied over time. Temporal averaging effectively removes the variability of visibility indexes associated with changing cloud cover and weather conditions, and changes in lighting conditions resulting from sun angle effects are best compensated for by restricting averaging to only certain times of the day.

    更新日期:2017-12-14
  • Atmospheric depositions of natural and anthropogenic trace elements on the Guliya ice cap (northwestern Tibetan Plateau) during the last 340 years
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-08
    M. Roxana Sierra-Hernández, Paolo Gabrielli, Emilie Beaudon, Anna Wegner, Lonnie G. Thompson
    更新日期:2017-12-14
  • Statistical analysis and parameterization of the hygroscopic growth of the sub-micrometer urban background aerosol in Beijing
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-08
    Yu Wang, Zhijun Wu, Nan Ma, Yusheng Wu, Limin Zeng, Chunsheng Zhao, Alfred Wiedensohler

    The take-up of water of aerosol particles plays an important role in heavy haze formation over North China Plain, since it is related with particle mass concentration, visibility degradation, and particle chemistry. In the present study, we investigated the size-resolved hygroscopic growth factor (HGF) of sub-micrometer aerosol particles (smaller than 350 nm) on a basis of 9-month Hygroscopicity-Tandem Differential Mobility Analyzer measurement in the urban background atmosphere of Beijing. The mean hygroscopicity parameter (κ) values derived from averaging over the entire sampling period for particles of 50 nm, 75 nm, 100 nm, 150 nm, 250 nm, and 350 nm in diameters were 0.14 ± 0.07, 0.17 ± 0.05, 0.18 ± 0.06, 0.20 ± 0.07, 0.21 ± 0.09, and 0.23 ± 0.12, respectively, indicating the dominance of organics in the sub-micrometer urban aerosols. In the spring, summer, and autumn, the number fraction of hydrophilic particles increased with increasing particle size, resulting in an increasing trend of overall particle hygroscopicity with enhanced particle size. Differently, the overall mean κ values peaked in the range of 75–150 nm and decreased for particles larger than 150 nm in diameter during wintertime. Such size-dependency of κ in winter was related to the strong primary particle emissions from coal combustion during domestic heating period. The number fraction of hydrophobic particles such as freshly emitted soot decreased with increasing PM2.5 mass concentration, indicating aged and internal mixed particles were dominant in the severe particulate matter pollution. Parameterization schemes of the HGF as a function of relative humidity (RH) and particle size between 50 and 350 nm were determined for different seasons and pollution levels. The HGFs calculated from the parameterizations agree well with the measured HGFs at 20–90% RH. The parameterizations can be applied to determine the hygroscopic growth of aerosol particles at ambient conditions for the area of Beijing (ultrafine and fine particles) and the North China plain (fine particles).

    更新日期:2017-12-14
  • Analyses of odours from concentrated animal feeding operations: A review
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-08
    P. Guffanti, V. Pifferi, L. Falciola, V. Ferrante

    Concentrated Animal Feeding Operations (CAFOs) are widely present all over the world due to the high population demand for food and products of animal origin. However, they have generated several environmental concerns, including odour nuisance, which affects people health and quality of life. Odours from livestock are a very complex mixtures of molecules and their analytical investigation is highly demanding. Many works have been published regarding the study of odours from CAFOs, using different techniques and technologies to face the issue. Thus, the aim of this review paper is to summarize all the ways to study odours from CAFOs, starting from the sampling methods and then treating in general the principles of Dynamic Olfactometry, Gas Chromatography coupled with Mass Spectrometry and Electronic Noses. Finally, a deep literature summary of Gas Chromatography coupled with Mass Spectrometry and Electronic Noses applied to odours coming from poultry, dairy and swine feeding operations is reported. This work aims to make some order in this field and it wants to help future researchers to deal with this environmental problem, constituting a state-of-the-art in this field.

    更新日期:2017-12-14
  • Oxidative potential of ambient fine aerosol over a semi-urban site in the Indo-Gangetic Plain
    Atmos. Environ. (IF 3.629) Pub Date : 2017-12-06
    Anil Patel, Neeraj Rastogi

    Indo-Gangetic Plain (IGP) receives emissions from variety of pollutant sources such as post-harvest crop residue burning, vehicles, industries, power plants, and bio-fuel burning. Several studies have documented physical, chemical and optical properties of aerosol over the IGP; however, their oxidative potential (OP) has not yet documented. Present study reports the OP (measured through dithiothreitol (DTT) assay) of soluble particulate matter smaller than 2.5 μm aerodynamic diameter (PM2.5) over Patiala (30.3°N, 76.4°E, 249 m amsl), a semi-urban site located in the IGP, during winter 2014. Volume-normalized OP (range: 1.3–7.2 nmol DTT min−1 m−3, average: 3.8 ± 1.4, 1σ) is found to be ∼3 to 20 times higher, and mass-normalized OP (range: 13-50 pmol DTT min−1 μg−1, average: 27 ± 8, 1σ) is found to be similar or higher than those documented in literature. Further, observed OP is found to depend more on PM2.5 composition rather than mass concentration. Mass fractions of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) correlate positively whereas that of secondary inorganic aerosol (SIA, sum of the concentrations of View the MathML source SO 4 2 − , View the MathML source NO 3 − and View the MathML source NH 4 + ) correlate negatively with OP μg−1 at considerable significance level (p < 0.05). Negative correlation of SIA with OP μg−1 has been assessed in laboratory experiment and attributed to their DTT inactive nature. It is suggested to use WSOC/SIA ratio as a measure of DTT activity of secondary particles over the study region. Further, biomass burning derived species are observed to be more DTT active than those derived from fossil fuel burning. It was also observed that the slope of OP μg−1 and WSOC/SIA ratio linear relationship enhances significantly in samples collected during days following foggy nights in comparison to that in samples collected during non-foggy period, which may be due to the production of redox-active species by fog processing. Such studies have implications in assessing the effect of ambient aerosol on atmospheric chemistry, air quality and human health.

    更新日期:2017-12-14
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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