Simultaneous measurements of urban and rural particles in Beijing – Part 1: Chemical composition and mixing state

Abstract. Two single-particle aerosol mass spectrometers (SPAMSs) were deployed simultaneously at an urban and a rural site in Beijing during an intensive field campaign from 1 to 29 November 2016 to investigate the source and process of airborne particles in Beijing. In the first part of this research, we report the single-particle chemical composition, mixing state, and evolution at both sites. A total of 96 % and 98 % of collected particles were carbonaceous at the urban and rural sites, respectively. Five particle categories, including elemental carbon (EC), organic carbon (OC), internal-mixed EC and OC (ECOC), potassium-rich (K-rich), and metals, were observed at both sites. The categories were partitioned into particle types depending on different atmospheric processing stages. A total of 17 particle types were shared at both sites. In the urban area, nitrate-containing particle types, such as EC-Nit (Nit: nitrate) and ECOC-Nit, were enriched especially at night, sulfate-containing particles were transported when wind speed was high, and ECOC-Nit-Sul (Sul: sulfate) were mostly aged locally. In sum, these processed particles added up to 85.3 % in the urban areas. In the rural area, regional particles were abundant, but freshly emitted ECOC and OC had distinct patterns that were pronounced at cooking and heating times. Biomass burning, traffic, and coal burning were major sources of particulate matter (PM2.5) in both rural and urban areas. Moreover, particles from the steel industry located in the south were also identified. In summary, the chemical composition of urban and rural particle types was similar in Beijing; the urban particles were influenced significantly by rural processing and transport. The work is useful to understand the evolution of urban and rural particles in Beijing during winter.

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Simultaneous Measurement of Urban and Rural Single Particles in Beijing, Part I: Chemical Composition and Mixing State

10.5194/acp-2019-933 ◽

2020 ◽

Author(s):

Yang Chen ◽

Jing Cai ◽

Zhichao Wang ◽

Chao Peng ◽

Xiaojiang Yao ◽

...

Keyword(s):

Chemical Composition ◽

Single Particle ◽

Urban Areas ◽

Heating Time ◽

Rural Site ◽

Mixing State ◽

Mass Spectrometers ◽

Rural And Urban Areas ◽

Rural And Urban ◽

Rural Sites

Abstract. Two single particle aerosol mass spectrometers (SPAMS) were deployed simultaneously at an urban and a rural site in Beijing during an intensive field campaign from 1st to 29th Nov 2016 to investigate the source and process of airborne particles in Beijing. In the first part of this research, we report the single-particle chemical composition, mixing state, and evolution at both sites. 96 % and 98 % of collected particles were carbonaceous at the urban and rural sites, respectively. Five particle categories, including elemental carbon (EC), organic carbon (OC), internal-mixed EC and OC (ECOC), potassium-rich (K-rich), and Metals were observed at both sites. The categories were partitioned into particle types depending on different atmospheric processing stages. Seventeen particle types were shared at both sites. In the urban area, nitrate-containing particle types, such as EC-Nit and ECOC-Nit, were enriched, especially at night; sulfate-containing particles were transported when wind speed was high; ECOC-Nit-Sul were mostly local-aged. In sum, these processed particles took up to 85.3 % in the urban areas. In the rural area, regional particles were abundant, but freshly emitted ECOC and OC had distinct patterns that were pronounced at cooking and heating time. Biomass burning, traffic, and coal burning were major sources of PM2.5 in both rural and urban areas. Besides, the particles from the steel industry located in the south were also identified. In summary, the chemical composition of urban and rural particle types was similar in Beijing; the urban particles were influenced significantly by rural processing and transport. The work is useful to understand the evolution of urban and rural particles in Beijing during winter.

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Earthen Architecture in Greece: Traditional Techniques and Revaluation

Heritage ◽

10.3390/heritage3040068 ◽

2020 ◽

Vol 3 (4) ◽

pp. 1237-1268

Author(s):

Αpostolos Mousourakis ◽

Maria Arakadaki ◽

Sofoklis Kotsopoulos ◽

Iordanis Sinamidis ◽

Tina Mikrou ◽

...

Keyword(s):

Urban Areas ◽

Primary Role ◽

Traditional Architecture ◽

Rural And Urban Areas ◽

Rural And Urban ◽

Construction Techniques ◽

Building Information ◽

Rural Sites ◽

Earthen Architecture ◽

Earthen Buildings

A big part of traditional architecture both in rural and urban areas in the Greek territory has been built with raw earth. The aim of this paper is to present earthen buildings’ constructions in Greece and show their important contribution to our heritage. The use of earth as a basic constructing material has given different earthen building cultures and techniques. Earthen construction encloses many varied uses and applications, as walls or as plasters. In different periods of time and historical contexts, from the indigenous inhabitants to the neighborhoods of the refugees of Asia Minor Catastrophe, the earth constructions had a primary role. The existence of earthen architecture was investigated in urban and rural sites in Greece. Building information, documentation, and records of buildings’ design, construction techniques, elements, and systems are presented. Today, there is still a rich architectural heritage throughout the country, which has lasted through the years and withstood seismic activities and poor conservation.

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Quantitative determination of carbonaceous particle mixing state in Paris using single particle mass spectrometer and aerosol mass spectrometer measurements

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-10345-2013 ◽

2013 ◽

Vol 13 (4) ◽

pp. 10345-10393

Author(s):

R. M. Healy ◽

J. Sciare ◽

L. Poulain ◽

M. Crippa ◽

A. Wiedensohler ◽

...

Keyword(s):

Chemical Composition ◽

Mass Spectrometer ◽

Single Particle ◽

Organic Aerosol ◽

Particle Mass ◽

Mixing State ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass ◽

Particle Mixing ◽

Mixing States

Abstract. Single particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been estimated using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulphate and potassium were compared with concurrent measurements from an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal/optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived mass concentrations reproduced the variability of these species well (R2 = 0.67–0.78), and ten discrete mixing states for carbonaceous particles were identified and quantified. Potassium content was used to identify particles associated with biomass combustion. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorization, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulphate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA/EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidized OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the heterogeneity of primary and secondary organic aerosol mixing states in Paris. Examination of the temporal behaviour and chemical composition of the ATOFMS classes also enabled estimation of the relative contribution of transported emissions of each chemical species and total particle mass in the size range investigated. Only 22% of the total ATOFMS-derived particle mass was apportioned to fresh, local emissions, with 78% apportioned to regional/continental scale emissions.

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Simulation of particle diversity and mixing state over Greater Paris: a model–measurement inter-comparison

Faraday Discussions ◽

10.1039/c5fd00175g ◽

2016 ◽

Vol 189 ◽

pp. 547-566 ◽

Cited By ~ 16

Author(s):

Shupeng Zhu ◽

Karine N. Sartelet ◽

Robert M. Healy ◽

John C. Wenger

Keyword(s):

Chemical Composition ◽

Single Particle ◽

Rural Areas ◽

Urban Areas ◽

Chem Phys ◽

Mixing State ◽

Average Value ◽

Internal Mixing ◽

State Index ◽

Different Sources

Air quality models are used to simulate and forecast pollutant concentrations, from continental scales to regional and urban scales. These models usually assume that particles are internally mixed, i.e. particles of the same size have the same chemical composition, which may vary in space and time. Although this assumption may be realistic for continental-scale simulations, where particles originating from different sources have undergone sufficient mixing to achieve a common chemical composition for a given model grid cell and time, it may not be valid for urban-scale simulations, where particles from different sources interact on shorter time scales. To investigate the role of the mixing state assumption on the formation of particles, a size-composition resolved aerosol model (SCRAM) was developed and coupled to the Polyphemus air quality platform. Two simulations, one with the internal mixing hypothesis and another with the external mixing hypothesis, have been carried out for the period 15 January to 11 February 2010, when the MEGAPOLI winter field measurement campaign took place in Paris. The simulated bulk concentrations of chemical species and the concentrations of individual particle classes are compared with the observations of Healy et al. (Atmos. Chem. Phys., 2013, 13, 9479–9496) for the same period. The single particle diversity and the mixing-state index are computed based on the approach developed by Riemer et al. (Atmos. Chem. Phys., 2013, 13, 11423–11439), and they are compared to the measurement-based analyses of Healy et al. (Atmos. Chem. Phys., 2014, 14, 6289–6299). The average value of the single particle diversity, which represents the average number of species within each particle, is consistent between simulation and measurement (2.91 and 2.79 respectively). Furthermore, the average value of the mixing-state index is also well represented in the simulation (69% against 59% from the measurements). The spatial distribution of the mixing-state index shows that the particles are not mixed in urban areas, while they are well mixed in rural areas. This indicates that the assumption of internal mixing traditionally used in transport chemistry models is well suited to rural areas, but this assumption is less realistic for urban areas close to emission sources.

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Quantitative determination of carbonaceous particle mixing state in Paris using single-particle mass spectrometer and aerosol mass spectrometer measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-9479-2013 ◽

2013 ◽

Vol 13 (18) ◽

pp. 9479-9496 ◽

Cited By ~ 80

Author(s):

R. M. Healy ◽

J. Sciare ◽

L. Poulain ◽

M. Crippa ◽

A. Wiedensohler ◽

...

Keyword(s):

Chemical Composition ◽

Mass Spectrometer ◽

Single Particle ◽

Organic Aerosol ◽

Particle Mass ◽

Mixing State ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass ◽

Particle Mixing ◽

Mixing States

Abstract. Single-particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single-particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been determined using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulfate and potassium were compared with concurrent measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal–optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived estimated mass concentrations reproduced the variability of these species well (R2 = 0.67–0.78), and 10 discrete mixing states for carbonaceous particles were identified and quantified. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorisation, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulfate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA / EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidised OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the range of primary and secondary organic aerosol mixing states in Paris. Examination of the temporal behaviour and chemical composition of the ATOFMS classes also enabled estimation of the relative contribution of transported emissions of each chemical species and total particle mass in the size range investigated. Only 22% of the total ATOFMS-derived particle mass was apportioned to fresh, local emissions, with 78% apportioned to regional/continental-scale emissions.

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Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-12109-2014 ◽

2014 ◽

Vol 14 (22) ◽

pp. 12109-12132 ◽

Cited By ~ 31

Author(s):

S. Decesari ◽

J. Allan ◽

C. Plass-Duelmer ◽

B. J. Williams ◽

M. Paglione ◽

...

Keyword(s):

Chemical Composition ◽

Black Carbon ◽

Mass Spectrometer ◽

Organic Aerosol ◽

Spectroscopic Techniques ◽

Mixing State ◽

Mass Spectrometers ◽

Aerosol Mass Spectrometer ◽

Po Valley ◽

Aerosol Mass

Abstract. The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer – HR-ToF-AMS and soot particle aerosol mass spectrometer – SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in residual layers but still originating in northern Italy, while a substantial fraction (41%) was due to the most aged aerosols imported from transalpine areas. The different meteorological regimes also affected the BC mixing state: in periods of enhanced stagnation and recirculation of pollutants, the number fraction of the BC-containing particles determined by ATOFMS was 75% of the total, while in the days of enhanced ventilation of the planetary boundary layer (PBL), such fraction was significantly lower (50%) because of the relative greater influence of non-BC-containing aerosol local sources in the Po Valley. Overall, a full internal mixing between BC and the non-refractory aerosol chemical components was not observed during the experiment in this environment.

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Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-23173-2015 ◽

2015 ◽

Vol 15 (16) ◽

pp. 23173-23229

Author(s):

L. Xu ◽

L. R. Williams ◽

D. E. Young ◽

J. D. Allan ◽

H. Coe ◽

...

Keyword(s):

Biomass Burning ◽

Field Studies ◽

Rural Site ◽

Urban Site ◽

High Temporal Resolution ◽

Volatile Organics ◽

Mass Spectrometers ◽

Aerosol Mass ◽

Rural And Urban ◽

Wide Range

Abstract. The composition of PM1 (particulate matter with diameter less than 1 μm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two High-Resolution Time-of-Flight Aerosol Mass Spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the sources of OA are distinctly different. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC, measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere. Finally, we discuss the relationship between the OA volatility and atomic O : C and find that particles with a wide range of O : C could have similar mass fraction remaining after heating. This analysis emphasizes the importance of understanding the distribution of volatility and O : C in bulk OA.

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Chemical composition and mixing state of BC-containing particles and the implications on light absorption enhancement

10.5194/acp-2021-904 ◽

2021 ◽

Author(s):

Jiaxing Sun ◽

Yele Sun ◽

Conghui Xie ◽

Weiqi Xu ◽

Chun Chen ◽

...

Keyword(s):

Chemical Composition ◽

Light Absorption ◽

Radiative Forcing ◽

Bulk Composition ◽

Rural Site ◽

Absorption Enhancement ◽

Mixing State ◽

Rural Sites ◽

Primary Emissions ◽

The Impact

Abstract. The radiative forcing of black carbon (BC) depends strongly on its mixing state in different chemical environments. Here, we analyzed the chemical composition and mixing state of BC-containing particles by using a single particle aerosol mass spectrometer and investigated their impacts on light absorption enhancement (Eabs) at an urban (Beijing) and a rural site (Gucheng) in North China Plain. While the BC was dominantly mixed with organic carbon (OC), nitrate and sulfate at both urban and rural sites, the rural site showed much higher fraction of BC coated with OC and nitrate (36 % vs. 15 – 20 %). Moreover, the BC mixing state evolved significantly as a function of relative humidity with largely increased coatings of OC-nitrate and nitrate at high RH levels. By linking with the bulk composition of organic aerosol (OA), we found that the OC coated on BC comprised dominantly secondary OA in Beijing, while primary and secondary OA were similarly important in Gucheng. Furthermore, Eabs was highly dependent on the secondary inorganic aerosol coated on BC at both sites, while the coated primary OC also resulted in an Eabs of ~1.2 for relatively fresh BC particles at the rural site. Positive matrix factorization analysis was performed to quantify the impact of different mixing state on Eabs. Our results showed the small Eabs (1.06 ~ 1.11) for BC particles from fresh primary emissions, while the Eabs increased significantly above 1.3 when BC was aged rapidly with increased coatings of OC-nitrate or nitrate, and it can reach above 1.4 as sulfate was involved in BC aging.

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Gut Microbiome Changes with Acute Diarrheal Disease in Urban Versus Rural Settings in Northern Ecuador

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.20-0831 ◽

2021 ◽

Author(s):

Maria J. Soto-Girón ◽

Angela Peña-Gonzalez ◽

Janet K. Hatt ◽

Lorena Montero ◽

Maritza Páez ◽

...

Keyword(s):

Gut Microbiome ◽

Urban Areas ◽

Diarrheal Disease ◽

Rural Populations ◽

Urban Populations ◽

Rural And Urban Areas ◽

Rural And Urban ◽

Rural Settings ◽

Enteric Infections ◽

Rural Sites

Previous studies have reported lower fecal bacterial diversity in urban populations compared with those living in rural settings. However, most of these studies compare geographically distant populations from different countries and even continents. The extent of differences in the gut microbiome in adjacent rural versus urban populations, and the role of such differences, if any, during enteric infections remain poorly understood. To provide new insights into these issues, we sampled the gut microbiome of young children with and without acute diarrheal disease (ADD) living in rural and urban areas in northern Ecuador. Shotgun metagenomic analyses of non-ADD samples revealed small but significant differences in the abundance of microbial taxa, including a greater abundance of Prevotella and a lower abundance of Bacteroides and Alistipes in rural populations. Greater and more significant shifts in taxon abundance, metabolic pathway abundance, and diversity were observed between ADD and non-ADD status when comparing urban to rural sites (Welch’s t-test, P < 0.05). Collectively our data show substantial functional, diversity, and taxonomic shifts in the gut microbiome of urban populations with, ADD supporting the idea that the microbiome of rural populations may be more resilient to ADD episodes.

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