Partitioning of Black Carbon between ultrafine and fine particle modes in an urban airport vs. urban background environment

Abstract. The scope of this study was to estimate the contribution of fossil fuel and wood burning combustion to black carbon (BC) and carbon monoxide (CO) during wintertime, in Athens. For that purpose, in situ measurements of equivalent black carbon (eBC) and CO were simultaneously conducted in a suburban and an urban background monitoring site in Athens during the 3 months of winter 2014–2015. For the deconvolution of eBC into eBC emitted from fossil fuel (BCff) and wood burning (BCwb), a method based on the spectral dependency of the absorption of pure black carbon and brown carbon was used. Thereafter, BCwb and BCff estimated fractions were used along with measured CO concentrations in a multiple regression analysis, in order to quantify the contribution of each one of the combustion sources to the ambient CO levels. For a comparative analysis of the results, we additionally estimated the wood burning and fossil fuel contribution to CO, calculated on the basis of their CO ∕ NOx emission ratios. The results indicate that during wintertime BC and CO are mainly emitted by local sources within the Athens Metropolitan Area (AMA). Fossil fuel combustion, mainly from road traffic, is found to be the major contributor to both eBC in PM2.5 and CO ambient concentrations in AMA. However, wintertime wood burning makes a significant contribution to the observed eBC (of about 30 %) and CO concentrations (on average, 11 and 16 % of total CO in the suburban and urban background sites respectively). Both BC and CO from biomass burning (BCwb and COwb, respectively) present a clear diurnal pattern, with the highest concentrations during night-time, supporting the theory of local domestic heating being their main source.

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Comparison of measured residential black carbon levels outdoors and indoors with fixed-site monitoring data and with dispersion modelling

Environmental Science and Pollution Research ◽

10.1007/s11356-020-12134-8 ◽

2020 ◽

Author(s):

Olena Gruzieva ◽

Antonios Georgelis ◽

Niklas Andersson ◽

Tom Bellander ◽

Christer Johansson ◽

...

Keyword(s):

Time Series ◽

Black Carbon ◽

Health Effects ◽

Dispersion Model ◽

Monitoring Data ◽

Dispersion Modelling ◽

Night Time ◽

Urban Background ◽

Site Monitoring

AbstractEpidemiologic studies on health effects of air pollution usually rely on time-series of ambient monitoring data or on spatially modelled levels. Little is known how well these estimate residential outdoor and indoor levels. We investigated the agreement of measured residential black carbon (BC) levels outdoors and indoors with fixed-site monitoring data and with levels calculated using a Gaussian dispersion model. One-week residential outdoor and indoor BC measurements were conducted for 15 families living in central Stockholm. Time-series from urban background and street-level monitors were compared to these measurements. The observed weekly concentrations were also standardized to reflect annual averages, using urban background levels, and compared spatially to long-term levels as estimated by dispersion modelling. Weekly average outdoor BC level was 472 ng/m3 (range 261–797 ng/m3). The corresponding fixed-site urban background and street levels were 313 and 1039 ng/m3, respectively. Urban background variation explained 50% of the temporal variation in residential outdoor levels averaged over 24 h. Modelled residential long-term outdoor levels were on average comparable with the standardized measured home outdoor levels, and explained 49% of the spatial variability. The median indoor/outdoor ratio across all addresses was 0.79, with no difference between day and night time. Common exposure estimation approaches in the epidemiology of health effects related to BC displayed high validity for residencies in central Stockholm. Urban background monitored levels explained half of the outdoor day-to-day variability at residential addresses. Long-term dispersion modelling explained half of the spatial differences in outdoor levels. Indoor BC concentrations tended to be somewhat lower than outdoor levels.

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Input-Adaptive Proxy for Black Carbon as a Virtual Sensor

Sensors ◽

10.3390/s20010182 ◽

2019 ◽

Vol 20 (1) ◽

pp. 182 ◽

Cited By ~ 6

Author(s):

Pak Lun Fung ◽

Martha A. Zaidan ◽

Salla Sillanpää ◽

Anu Kousa ◽

Jarkko V. Niemi ◽

...

Keyword(s):

Air Quality ◽

Missing Data ◽

Black Carbon ◽

Street Canyon ◽

Ordinary Least Squares ◽

Coefficient Of Determination ◽

Data Set ◽

Virtual Sensor ◽

Urban Background ◽

Input Variables

Missing data has been a challenge in air quality measurement. In this study, we develop an input-adaptive proxy, which selects input variables of other air quality variables based on their correlation coefficients with the output variable. The proxy uses ordinary least squares regression model with robust optimization and limits the input variables to a maximum of three to avoid overfitting. The adaptive proxy learns from the data set and generates the best model evaluated by adjusted coefficient of determination (adjR2). In case of missing data in the input variables, the proposed adaptive proxy then uses the second-best model until all the missing data gaps are filled up. We estimated black carbon (BC) concentration by using the input-adaptive proxy in two sites in Helsinki, which respectively represent street canyon and urban background scenario, as a case study. Accumulation mode, traffic counts, nitrogen dioxide and lung deposited surface area are found as input variables in models with the top rank. In contrast to traditional proxy, which gives 20–80% of data, the input-adaptive proxy manages to give full continuous BC estimation. The newly developed adaptive proxy also gives generally accurate BC (street canyon: adjR2 = 0.86–0.94; urban background: adjR2 = 0.74–0.91) depending on different seasons and day of the week. Due to its flexibility and reliability, the adaptive proxy can be further extend to estimate other air quality parameters. It can also act as an air quality virtual sensor in support with on-site measurements in the future.

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Black carbon modeling in urban areas: investigating the influence of resuspension and non-exhaust emissions in streets using the Street-in-Grid model for inert particles (SinG-inert)

Geoscientific Model Development ◽

10.5194/gmd-14-7001-2021 ◽

2021 ◽

Vol 14 (11) ◽

pp. 7001-7019

Author(s):

Lya Lugon ◽

Jérémy Vigneron ◽

Christophe Debert ◽

Olivier Chrétien ◽

Karine Sartelet

Keyword(s):

Black Carbon ◽

Internal Combustion Engines ◽

Exhaust Emissions ◽

Emission Factors ◽

Traffic Emissions ◽

Policy Implications ◽

Background Concentrations ◽

Urban Background ◽

Particle Resuspension ◽

Grid Model

Abstract. Black carbon (BC) is a primary and inert pollutant often used as a traffic tracer. Even though its concentrations are generally low at the regional scale, BC presents very high concentrations in streets (at the local scale), potentially with important effects on human health and the environment. Modeling studies of BC concentrations usually underestimate BC concentrations due to uncertainties in both emissions and modeling. Both exhaust and non-exhaust traffic emissions present uncertainties, but the uncertainties with respect to non-exhaust emissions, such as tire, brake, and road wear as well as particle resuspension, are particularly high. In terms of modeling, street models do not always consider the two-way interactions between the local and regional scales. Using a two-way modeling approach, a street with high BC concentrations may influence urban background concentrations above the street, which can subsequently enhance the BC concentrations in the same street. This study uses the multiscale Street-in-Grid model (SinG) to simulate BC concentrations in a suburban street network in Paris, taking the two-way coupling between local and regional scales into account. The BC concentrations in streets proved to have an important influence on urban background concentrations. The two-way dynamic coupling leads to an increase in BC concentrations in large streets with high traffic emissions (with a maximal increase of about 48 %) as well as a decrease in narrow streets with low traffic emissions and low BC concentrations (with a maximal decrease of about 50 %). A new approach to estimate particle resuspension in streets is implemented, strictly respecting the mass balance on the street surface. The resuspension rate is calculated from the available deposited mass on the street surface, which is estimated based on particle deposition and wash-off parameterizations adapted to street-canyon geometries. The simulations show that particle resuspension presents a low contribution to BC concentrations, as the deposited mass is not significant enough to justify high resuspension rates. Non-exhaust emissions, such as brake, tire, and road wear, may largely contribute to BC emissions, with a contribution that is equivalent to exhaust emissions. Here, a sensitivity analysis of BC concentrations is performed by comparing simulations with different emission factors of tire, brake, and road wear. The different emission factors considered are estimated based on the literature. We found a satisfying model–measurement comparison using high tire wear emission factors, which may indicate that the tire emission factors usually used in Europe are probably underestimated. These results have important policy implications: public policies replacing internal combustion engines with electric vehicles may not eliminate BC air pollution but only reduce it by half.

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Representativeness and variability of PM2.5 mass concentrations and black carbon near traffic and urban background monitoring stations/Repräsentativität und Variabilität von PM2.5-Massenkonzentrationen und schwarzem Kohlenstoff in der Nähe von Verkehrs- und städtischen Luftgütemessstationen.

Gefahrstoffe ◽

10.37544/0949-8036-2019-06-31 ◽

2019 ◽

Vol 79 (06) ◽

pp. 217-226

Author(s):

H. D. Alas ◽

S. Pfeifer ◽

A. Wiesner ◽

B. Wehner ◽

K. Weinhold ◽

...

Keyword(s):

Air Pollution ◽

Black Carbon ◽

Urban Areas ◽

Mass Concentration ◽

Spatial Distributions ◽

Urban Background ◽

Regular Monitoring ◽

The City ◽

Mass Concentrations ◽

Monitoring Stations

Mobile measurements of PM2.5 and black carbon (BC) mass concentrations were performed near regular monitoring stations in order to gain deeper understanding of the drivers of pedestrian exposure to traffic-related air pollution. The following investigations have been done: A) Yearlong measurements in an area around a street canyon approximately 3 km airline distance from the city center of Leipzig showed that the spatial distributions of both pollutants are elevated during wintertime. The patterns of the BC mass concentration, however, consistently showed a strong influence from traffic emissions in the street, while the PM2.5 mass concentration was more dependent on the regional background and less on urban sources. B) Measurements in the city of Dresden near two regular monitoring stations, one at a roadside and one in urban background areas revealed differences between the two in terms of the BC mass concentrations, with slightly higher concentrations at the traffic area. However, no significant differences between the spatial distributions of PM2.5 mass concentrations were observed. The background measurements of the PM2.5 mass concentrations seem to be generally representative for the residential area. C) Measurements near a regular monitoring station located at a junction of the inner-city ring road of Leipzig showed that it is representative of its immediate vicinity in terms of BC mass concentrations. However, the PM2.5 mass concentration varied by a factor 2, reaching the highest levels near in the central tram station about 200 m away. The central tram station seems to significantly influence the PM2.5 mass concentration. These results of the three studies provide a better understanding of the variability of these two parameters in urban areas in Leipzig and Dresden, helping local policy makers to interpret better the measured air pollution.

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Long-term variability, source apportionment and spectral properties of black carbon at an urban background site in Athens, Greece

Atmospheric Environment ◽

10.1016/j.atmosenv.2019.117137 ◽

2020 ◽

Vol 222 ◽

pp. 117137 ◽

Cited By ~ 12

Author(s):

E. Liakakou ◽

I. Stavroulas ◽

D.G. Kaskaoutis ◽

G. Grivas ◽

D. Paraskevopoulou ◽

...

Keyword(s):

Black Carbon ◽

Source Apportionment ◽

Spectral Properties ◽

Urban Background ◽

Background Site ◽

Urban Background Site

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Black carbon and PM2.5 monitoring campaign on the roadside and residential urban background sites in the city of Tehran

Atmospheric Environment ◽

10.1016/j.atmosenv.2019.116928 ◽

2019 ◽

Vol 218 ◽

pp. 116928 ◽

Cited By ~ 3

Author(s):

Ahmad Taheri ◽

Pourya Aliasghari ◽

Vahid Hosseini

Keyword(s):

Black Carbon ◽

Urban Background ◽

Monitoring Campaign ◽

The City

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Spatiotemporal variation and trends of equivalent black carbon in the Helsinki metropolitan area in Finland

10.5194/acp-2020-201 ◽

2020 ◽

Author(s):

Krista Luoma ◽

Jarkko V. Niemi ◽

Aku Helin ◽

Minna Aurela ◽

Hilkka Timonen ◽

...

Keyword(s):

Time Series ◽

Black Carbon ◽

Metropolitan Area ◽

Cold Season ◽

Air Pollution Control ◽

Wood Combustion ◽

Urban Background ◽

Regional Background ◽

Different Types ◽

Helsinki Metropolitan Area

Abstract. In this study, we present results of 12 years of black carbon (BC) measurements at 14 different measurement sites around the Helsinki metropolitan area (HMA) and at one background site outside the HMA. The main local sources of BC in the HMA are traffic, and residential wood combustion in fireplaces and sauna stoves. All the BC measurements were conducted optically and therefore we refer to the measured BC as equivalent BC (eBC). Measurement stations were located at different types of environments that represented traffic environment (six sites), detached housing area (five sites), urban background (two sites), and regional background (two sites). The measurements of eBC were conducted during 2007–2018; however, the time period and the length of the time series varied from site to site. As expected, the largest annual mean eBC concentrations were measured at the traffic sites (0.67–2.64 μg m−3) and the lowest at the regional background sites (0.16–0.29 μg m−3). The annual mean eBC concentrations at the detached housing sites varied in the range of 0.64–0.80 μg m−3 and the annual mean eBC concentrations at the urban background sites varied in the range of 0.42–0.68 μg m−3. The clearest seasonal variation was observed at the detached housing sites, where the residential wood combustion increased the eBC concentrations during the cold season. Traffic rates and wood burning influenced the diurnal and weekly variations of eBC concentration in different types of environments. The dependency was not so clear for the other air pollutants, which were here NOx and mass of particles smaller than 2.5 μm (PM2.5). At four sites, which had at least four-year-long time series available, we observed that the eBC concentrations had statistically significant decreasing trends, which varied in the range of −10.4–−5.9 % yr−1. Compared to the trends determined at the urban and regional background sites, the absolute trends decreased the fastest at the traffic sites and especially during the morning rush hour. The relative long-term trends of eBC and NOx were similar to each other, and their concentrations decreased more rapidly than the concentration of PM2.5. The results indicate that especially the emissions from traffic have decreased in the HMA during the last decade. This shows that air pollution control, new emission standards and newer fleet of vehicles really have an effect in the air quality.

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