Benzene and Toluene in the surface air of North Eurasia from TROICA-12 campaign along the Trans-Siberian railway

Abstract. Volatile organic compounds (VOCs) were measured by proton transfer reaction – mass spectrometry (PTR-MS) on a mobile laboratory in a transcontinental TROICA-12 (21.07.2008–04.08.2008) campaign along the Trans-Siberian railway from Moscow to Vladivostok. Surface concentrations of benzene (C6H6) and toluene (C7H8) along with non-methane hydrocarbons (NMHCs), CO, O3, SO2, NO, NO2 and meteorology are analyzed in this study to identify the main sources of benzene and toluene along the Trans-Siberian railway. The most measurements in the TROICA-12 campaign were conducted under low-wind/stagnant conditions in moderately (~ 78 % of measurements) to weakly polluted (~ 20 % of measurements) air directly affected by regional anthropogenic sources adjacent to the railroad. Only 2 % of measurements were identified as characteristic of highly polluted urban atmosphere. Maximum values of benzene and toluene during the campaign reached 36.5 ppb and 45.6 ppb, correspondingly, which is significantly less than their one-time maximum permissible concentrations (94 and 159 ppb for benzene and toluene, correspondingly). About 90 % of benzene and 65 % of toluene content is attributed to motor vehicle transport and 10 % and 20 %, correspondingly, provided by the other local and regional-scale sources. The highest average concentrations of benzene and toluene are measured in the industrial regions of the European Russia (up to 0.3 and 0.4 ppb for benzene and toluene, correspondingly) and south Siberia (up to 0.2 and 0.4 ppb for benzene and toluene, correspondingly). Total contribution of benzene and toluene to photochemical ozone production along the Trans-Siberian railway is about 16 % compared to the most abundant biogenic VOC – isoprene. This contribution, however, is found to be substantially higher (up to 60–70 %) in urbanized areas along the railroad suggesting important role of anthropogenic pollutant sources in regional ozone photochemistry and air quality.

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Benzene and toluene in the surface air of northern Eurasia from TROICA-12 campaign along the Trans-Siberian Railway

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-5501-2017 ◽

2017 ◽

Vol 17 (8) ◽

pp. 5501-5514 ◽

Cited By ~ 11

Author(s):

Andrey I. Skorokhod ◽

Elena V. Berezina ◽

Konstantin B. Moiseenko ◽

Nikolay F. Elansky ◽

Igor B. Belikov

Keyword(s):

Motor Vehicle ◽

Regional Scale ◽

Ozone Production ◽

Anthropogenic Sources ◽

Northern Eurasia ◽

Exposure Limits ◽

Total Contribution ◽

Short Term Exposure ◽

South Siberia ◽

Anthropogenic Pollutant

Abstract. Volatile organic compounds (VOCs) were measured by proton transfer reaction mass spectrometry (PTR-MS) on a mobile laboratory in a transcontinental TROICA-12 (21 July–4 August 2008) campaign along the Trans-Siberian Railway from Moscow to Vladivostok. Surface concentrations of benzene (C6H6) and toluene (C7H8) along with non-methane hydrocarbons (NMHCs), CO, O3, SO2, NO, NO2 and meteorology are analyzed in this study to identify the main sources of benzene and toluene along the Trans-Siberian Railway. The most measurements in the TROICA-12 campaign were conducted under low-wind/stagnant conditions in moderately ( ∼  78 % of measurements) to weakly polluted ( ∼  20 % of measurements) air directly affected by regional anthropogenic sources adjacent to the railway. Only 2 % of measurements were identified as characteristic of highly polluted urban atmosphere. Maximum values of benzene and toluene during the campaign reached 36.5 and 45.6 ppb, respectively, which is significantly less than their short-term exposure limits (94 and 159 ppb for benzene and toluene, respectively). About 90 % of benzene and 65 % of toluene content is attributed to motor vehicle transport and 10 and 20 %, respectively, provided by the other local- and regional-scale sources. The highest average concentrations of benzene and toluene are measured in the industrial regions of the European Russia (up to 0.3 and 0.4 ppb for benzene and toluene, respectively) and south Siberia (up to 0.2 and 0.4 ppb for benzene and toluene, respectively). Total contribution of benzene and toluene to photochemical ozone production along the Trans-Siberian Railway is about 16 % compared to the most abundant organic VOC – isoprene. This contribution, however, is found to be substantially higher (up to 60–70 %) in urbanized areas along the railway, suggesting an important role of anthropogenic pollutant sources in regional ozone photochemistry and air quality.

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Groundwater vulnerability assessment: from overlay methods to statistical methods in the Lombardy Plain area

Acque Sotterranee-Italian Journal of Groundwater ◽

10.7343/as-2017-276 ◽

2017 ◽

Vol 6 (2) ◽

Cited By ~ 4

Author(s):

Stefania Stevenazzi ◽

Marco Masetti ◽

Giovanni Pietro Beretta

Keyword(s):

Land Use Planning ◽

Vulnerability Assessment ◽

Industrial Development ◽

Regional Scale ◽

Scientific Progress ◽

Groundwater Vulnerability ◽

Anthropogenic Sources ◽

Plain Area ◽

Groundwater Vulnerability Assessment ◽

Vulnerability Maps

Groundwater is among the most important freshwater resources. Worldwide, aquifers are experiencing an increasing threat of pollution from urbanization, industrial development, agricultural activities and mining enterprise. Thus, practical actions, strategies and solutions to protect groundwater from these anthropogenic sources are widely required. The most efficient tool, which helps supporting land use planning, while protecting groundwater from contamination, is represented by groundwater vulnerability assessment. Over the years, several methods assessing groundwater vulnerability have been developed: overlay and index methods, statistical and process-based methods. All methods are means to synthesize complex hydrogeological information into a unique document, which is a groundwater vulnerability map, useable by planners, decision and policy makers, geoscientists and the public. Although it is not possible to identify an approach which could be the best one for all situations, the final product should always be scientific defensible, meaningful and reliable. Nevertheless, various methods may produce very different results at any given site. Thus, reasons for similarities and differences need to be deeply investigated. This study demonstrates the reliability and flexibility of a spatial statistical method to assess groundwater vulnerability to contamination at a regional scale. The Lombardy Plain case study is particularly interesting for its long history of groundwater monitoring (quality and quantity), availability of hydrogeological data, and combined presence of various anthropogenic sources of contamination. Recent updates of the regional water protection plan have raised the necessity of realizing more flexible, reliable and accurate groundwater vulnerability maps. A comparison of groundwater vulnerability maps obtained through different approaches and developed in a time span of several years has demonstrated the relevance of the continuous scientific progress, recognizing strengths and weaknesses of each research.

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Sources of black carbon aerosols in South Asia and surrounding regions during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-5415-2015 ◽

2015 ◽

Vol 15 (10) ◽

pp. 5415-5428 ◽

Cited By ~ 32

Author(s):

R. Kumar ◽

M. C. Barth ◽

V. S. Nair ◽

G. G. Pfister ◽

S. Suresh Babu ◽

...

Keyword(s):

Spatial Variability ◽

South Asia ◽

Black Carbon ◽

Biomass Burning ◽

Regional Scale ◽

Anthropogenic Sources ◽

Radiation Budget ◽

Anthropogenic Emissions ◽

Spatial And Temporal Variability ◽

Mass Concentrations

Abstract. This study examines differences in the surface black carbon (BC) aerosol loading between the Bay of Bengal (BoB) and the Arabian Sea (AS) and identifies dominant sources of BC in South Asia and surrounding regions during March–May 2006 (Integrated Campaign for Aerosols, Gases and Radiation Budget, ICARB) period. A total of 13 BC tracers are introduced in the Weather Research and Forecasting Model coupled with Chemistry to address these objectives. The model reproduced the temporal and spatial variability of BC distribution observed over the AS and the BoB during the ICARB ship cruise and captured spatial variability at the inland sites. In general, the model underestimates the observed BC mass concentrations. However, the model–observation discrepancy in this study is smaller compared to previous studies. Model results show that ICARB measurements were fairly well representative of the AS and the BoB during the pre-monsoon season. Elevated BC mass concentrations in the BoB are due to 5 times stronger influence of anthropogenic emissions on the BoB compared to the AS. Biomass burning in Burma also affects the BoB much more strongly than the AS. Results show that anthropogenic and biomass burning emissions, respectively, accounted for 60 and 37% of the average ± standard deviation (representing spatial and temporal variability) BC mass concentration (1341 ± 2353 ng m−3) in South Asia. BC emissions from residential (61%) and industrial (23%) sectors are the major anthropogenic sources, except in the Himalayas where vehicular emissions dominate. We find that regional-scale transport of anthropogenic emissions contributes up to 25% of BC mass concentrations in western and eastern India, suggesting that surface BC mass concentrations cannot be linked directly to the local emissions in different regions of South Asia.

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Analysis of a Regional Scale Chemical-Transport Model to Investigate the Potential Capability of Satellites for Identifying a Widespread Air Pollution Event

10.20944/preprints201708.0020.v1 ◽

2017 ◽

Author(s):

Jason Welsh ◽

Jack Fishman

Keyword(s):

Transport Model ◽

Regional Scale ◽

Ozone Production ◽

Metropolitan Region ◽

Trace Gas ◽

Chemical Transport Model ◽

Satellite Measurements ◽

Pollution Event ◽

Surface O3 ◽

Good Agreement

We use a regional scale photochemical transport model to investigate the surface concentrations and column integrated amounts of ozone (O3) and nitrogen dioxide (NO2) during a pollution event that occurred in the St. Louis metropolitan region in 2012. These trace gases will be two of the primary constituents that will be measured by TEMPO, an instrument on a geostationary platform, which will result in a dataset that has hourly temporal resolution during the daytime and ~4 km spatial resolution. Although air quality managers are most concerned with surface concentrations, satellite measurements provide a quantity that reflects a column amount, which may or may not be directly relatable to what is measured at the surface. The model results provide good agreement with observed surface O3 concentrations, which is the only trace gas dataset that can be used for verification. The model shows that a plume of O3 extends downwind from St. Louis and contains an integrated amount of ozone of ~ 16 DU (1 DU = 2.69 x 1016 mol. cm-2), a quantity that is two to three times lower than what was observed by satellite measurements during two massive pollution episodes in the 1980s. Based on the smaller isolatable emissions coming from St. Louis, this quantity is not unreasonable, but may also reflect the reduction of photochemical ozone production due to the implementation of emission controls that have gone into effect in the past few decades.

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Ozone production in the megacities of Tianjin and Shanghai, China: a comparative study

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-9161-2012 ◽

2012 ◽

Vol 12 (4) ◽

pp. 9161-9194 ◽

Cited By ~ 1

Author(s):

L. Ran ◽

C. S. Zhao ◽

W. Y. Xu ◽

M. Han ◽

X. Q. Lu ◽

...

Keyword(s):

Comparative Study ◽

Surface Ozone ◽

Regional Scale ◽

Yangtze River Delta ◽

Scientific Basis ◽

Ozone Production ◽

Ozone Pollution ◽

Light Alkenes ◽

Highly Nonlinear ◽

Ozone Precursor

Abstract. Rapid economic growth has given rise to a significant increase in ozone precursor emissions in many regions of China, especially in the densely populated North China Plain (NCP) and Yangtze River Delta (YRD). Improved understanding of ozone formation in response to different precursor emissions is imperative to address the highly nonlinear ozone problem and to provide a solid scientific basis for efficient ozone abatement in these regions. A comparative study on ozone photochemical production in summer has thus been carried out in the megacities of Tianjin (NCP) and Shanghai (YRD). Two intensive field campaigns were carried out respectively at an urban and a suburban site of Tianjin, in addition to routine monitoring of trace gases in Shanghai, providing data sets of surface ozone and its precursors including nitrogen oxides (NOx) and various volatile organic compounds (VOCs). Ozone pollution was found to be more severe in Tianjin than in Shanghai during the summer, either based on the frequency or the duration of high ozone events. Such differences might be attributed to the large amount of highly reactive VOC mixture in the Tianjin region. It is found that industry related species like light alkenes were of particular importance in both urban and suburban Tianjin, while in Shanghai aromatics dominate. In general, the ozone problem in Shanghai is on an urban scale. Stringent control policies on local emissions would help reduce the occurrence of high ozone concentrations. By contrast, ozone pollution in Tianjin is a regional problem. Combined efforts to reduce ozone precursor emissions on a regional scale must be undertaken to bring the ozone problem under control.

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Characterization of nighttime formation of particulate organic nitrates based on high-resolution aerosol mass spectrometry in an urban atmosphere in China

10.5194/acp-2018-1009 ◽

2018 ◽

Author(s):

Kuangyou Yu ◽

Qiao Zhu ◽

Ke Du ◽

Xiao-Feng Huang

Keyword(s):

High Resolution ◽

Factorization Method ◽

Urban Atmosphere ◽

Ozone Production ◽

Urban Site ◽

High Time Resolution ◽

Organic Nitrates ◽

Aerosol Mass ◽

Polluted Atmosphere

Abstract. Organic nitrates are important atmospheric species that significantly affect the cycling of NOx and ozone production. However, characterization of particulate organic nitrates and their sources in inorganic nitrate-abundant particles in polluted atmosphere is a big challenge, and has been little performed in the literature. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in South China from 2015 to 2016 to characterize particulate organic nitrates with high time resolution. Based on two different data processing methods, 13–21 % of the total measured nitrates was identified to be organic nitrates in spring, 41–64 % in summer and 16%–25 % in autumn; however, in winter, most measured nitrates were inorganic. The good correlation between organic nitrates and fresh secondary organic aerosol identified by the positive matrix factorization method at night rather than in the daytime indicated a potentially important role of nighttime secondary formation. Therefore, we theoretically estimated nighttime NO3 radical concentrations and SOA formation using the various VOCs measured simultaneously. Consequently, the calculated products of monoterpene reacting with NO3 agreed well with the organic nitrates in terms of both concentration and variation, suggesting that the biogenic VOC reactions with NO3 at night are the dominant formation pathway for particulate organic nitrates in polluted atmosphere, despite of much higher abundance of anthropogenic VOCs.

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High-resolution inversion of methane emissions in the Southeast US using SEAC<sup>4</sup>RS aircraft observations of atmospheric methane: anthropogenic and wetland sources

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-6483-2018 ◽

2018 ◽

Vol 18 (9) ◽

pp. 6483-6491 ◽

Cited By ~ 12

Author(s):

Jian-Xiong Sheng ◽

Daniel J. Jacob ◽

Alexander J. Turner ◽

Joannes D. Maasakkers ◽

Melissa P. Sulprizio ◽

...

Keyword(s):

Oil And Gas ◽

Source Region ◽

Regional Scale ◽

Methane Emissions ◽

Gas Production ◽

Anthropogenic Sources ◽

Oil And Gas Production ◽

Error Characterization ◽

The Mean ◽

Southeast Us

Abstract. We use observations of boundary layer methane from the SEAC4RS aircraft campaign over the Southeast US in August–September 2013 to estimate methane emissions in that region through an inverse analysis with up to 0.25∘×0.3125∘ (25×25 km2) resolution and with full error characterization. The Southeast US is a major source region for methane including large contributions from oil and gas production and wetlands. Our inversion uses state-of-the-art emission inventories as prior estimates, including a gridded version of the anthropogenic EPA Greenhouse Gas Inventory and the mean of the WetCHARTs ensemble for wetlands. Inversion results are independently verified by comparison with surface (NOAA∕ESRL) and column (TCCON) methane observations. Our posterior estimates for the Southeast US are 12.8±0.9 Tg a−1 for anthropogenic sources (no significant change from the gridded EPA inventory) and 9.4±0.8 Tg a−1 for wetlands (27 % decrease from the mean in the WetCHARTs ensemble). The largest source of error in the WetCHARTs wetlands ensemble is the land cover map specification of wetland areal extent. Our results support the accuracy of the EPA anthropogenic inventory on a regional scale but there are significant local discrepancies for oil and gas production fields, suggesting that emission factors are more variable than assumed in the EPA inventory.

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Volatile and intermediate volatility organic compounds in suburban Paris: variability, origin and importance for SOA formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-10439-2014 ◽

2014 ◽

Vol 14 (19) ◽

pp. 10439-10464 ◽

Cited By ~ 47

Author(s):

W. Ait-Helal ◽

A. Borbon ◽

S. Sauvage ◽

J. A. de Gouw ◽

A. Colomb ◽

...

Keyword(s):

Organic Carbon ◽

Particulate Organic Carbon ◽

Organic Compounds ◽

Regional Scale ◽

Integrated Approach ◽

Anthropogenic Sources ◽

Time Resolved ◽

Times Series

Abstract. Measurements of gaseous and particulate organic carbon were performed during the MEGAPOLI experiments, in July 2009 and January–February 2010, at the SIRTA observatory in suburban Paris. Measurements comprise primary and secondary volatile organic compounds (VOCs), of both anthropogenic and biogenic origins, including C12–C16 n-alkanes of intermediate volatility (IVOCs), suspected to be efficient precursors of secondary organic aerosol (SOA). The time series of gaseous carbon are generally consistent with times series of particulate organic carbon at regional scale, and are clearly affected by meteorology and air mass origin. Concentration levels of anthropogenic VOCs in urban and suburban Paris were surprisingly low (2–963 ppt) compared to other megacities worldwide and to rural continental sites. Urban enhancement ratios of anthropogenic VOC pairs agree well between the urban and suburban Paris sites, showing the regional extent of anthropogenic sources of similar composition. Contrary to other primary anthropogenic VOCs (aromatics and alkanes), IVOCs showed lower concentrations in winter (< 5 ppt) compared to summer (13–27 ppt), which cannot be explained by the gas-particle partitioning theory. Higher concentrations of most oxygenated VOCs in winter (18–5984 ppt) suggest their dominant primary anthropogenic origin. The respective role of primary anthropogenic gaseous compounds in regional SOA formation was investigated by estimating the SOA mass concentration expected from the anthropogenic VOCs and IVOCs (I / VOCs) measured at SIRTA. From an integrated approach based on emission ratios and SOA yields, 38 % of the SOA measured at SIRTA is explained by the measured concentrations of I / VOCs, with a 2% contribution by C12–C16 n-alkane IVOCs. From the results of an alternative time-resolved approach, the average IVOC contribution to SOA formation is estimated to be 7%, which is half of the average contribution of the traditional aromatic compounds (15%). Both approaches, which are based on in situ observations of particular I / VOCs, emphasize the importance of the intermediate volatility compounds in the SOA formation, and support previous results from chamber experiments and modeling studies. They also support the need to make systematic the IVOCs' speciated measurement during field campaigns.

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A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-947-2012 ◽

2012 ◽

Vol 5 (1) ◽

pp. 947-978 ◽

Cited By ~ 1

Author(s):

J. L. Ambrose ◽

Y. Zhou ◽

K. Haase ◽

H. R. Mayne ◽

R. Talbot ◽

...

Keyword(s):

Biomass Burning ◽

Hydrogen Cyanide ◽

Regional Scale ◽

Proton Transfer Reaction ◽

Mean Value ◽

Porous Polymer ◽

Lower Atmosphere ◽

Atmospheric Conditions ◽

Mixing Ratios ◽

And Performance

Abstract. A gas-chromatographic (GC) instrument was developed for measuring hydrogen cyanide (HCN) in the lower atmosphere. The main features of the instrument are (1) a cryogen-free cooler for sample dehumidification and enrichment, (2) a porous polymer PLOT column for analyte separation, (3) a flame thermionic detector (FTD) for sensitive and selective detection and (4) a dynamic dilution system for calibration. We deployed the instrument for a ~4 month period from January–June 2010 at the AIRMAP atmospheric monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of measurements made during 3–31 March is presented here with a detailed description of the instrument features and performance characteristics. The temporal resolution of the measurements was ~20 min, with a 75 s sample capture time. The 1σ measurement precision was <10% and the instrument response linearity was excellent on a calibration scale of 0.10–0.75 ppbv (±5%). The estimated method detection limit (MDL) and accuracy were 0.021 ppbv and 15%, respectively. From 3–31 March 2010, ambient HCN mixing ratios ranged from 0.15–1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared to agree well with tropospheric column measurements reported previously. The GC-FTD HCN measurements were strongly correlated with acetonitrile (CH3CN) measured concurrently with a proton transfer-reaction mass spectrometer (PTR-MS), as anticipated given our understanding that the nitriles share a common primary biomass burning source to the global atmosphere. The nitriles were overall only weakly correlated with CO, which is reasonable considering the greater diversity of sources for CO. However, strong correlations with CO were observed on several nights under stable atmospheric conditions and suggest regional combustion-based sources for the nitriles. These results demonstrate that the GC-FTD instrument is capable of making long term, in-situ measurements of HCN in the lower atmosphere. To date, similar measurements have not been performed, yet they are critically needed to (1) better evaluate the regional scale distribution of HCN in the atmosphere and (2) discern the influence of biomass burning on surface air composition in remote regions.

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Particle number size distributions in urban air before and after volatilisation

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-4643-2010 ◽

2010 ◽

Vol 10 (10) ◽

pp. 4643-4660 ◽

Cited By ~ 50

Author(s):

W. Birmili ◽

K. Heinke ◽

M. Pitz ◽

J. Matschullat ◽

A. Wiedensohler ◽

...

Keyword(s):

Particle Size ◽

Volatile Compounds ◽

Size Distribution ◽

Particle Number ◽

Volume Concentration ◽

Urban Atmosphere ◽

Anthropogenic Sources ◽

Particulate Emissions ◽

Size Distributions ◽

Before And After

Abstract. Aerosol particle number size distributions (size range 0.003–10 μm) in the urban atmosphere of Augsburg (Germany) were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm−3, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass. Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C), allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R2=0.9) suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could be determined as a function of particle size. The results indicated that particles >60 nm contain a significantly higher fraction of non-volatile compounds, most likely black carbon, than particles <60 nm. The results are relevant for future health-related studies in that they explore the size distribution and time-dependent behaviour of the refractory component of the urban aerosol over an extended time period.

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