Quantifying the influences of atmospheric stability on air pollution in Lanzhou, China, using a radon-based stability monitor
TL;DR: In this paper, a technique recently developed for stability classification using a research-quality dual-flow-loop two-filter radon detector is adapted for use with a commercially available radon-based stability monitor.
About: This article is published in Atmospheric Environment.The article was published on 2015-04-01. It has received 57 citations till now. The article focuses on the topics: Radon.
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TL;DR: In this article, TSP composition data and backward trajectory analysis results at Gosan, Korea, for 10 years between March 1992 and February 2002 are studied to understand the site characteristics and the relationship between the aerosol composition and meteorological conditions.
Abstract: TSP composition data and backward trajectory analysis results at Gosan, Korea, for 10 years between March 1992 and February 2002 are studied to understand the site characteristics and the relationship between the aerosol composition and meteorological conditions. The average non-sea-salt-(nss)-sulfate concentration (6.74 μg m -3 ) is higher than those observed at other background areas in the world. It was demonstrated that the observed high level of sulfate is due to transport from outside the site. The concentrations of nss-sulfate/ammonium/nss-potassium, sodium/chloride/magnesium, and nss-calcium/nitrate show a strong relationship, suggesting their common emissions sources and/or transport pattern. It is likely that the concentration ratio of nss-sulfate to nitrate is decreasing because of the increase of the nitrate concentration. On the basis of various measurement and emission estimate studies, it is suggested that this trend is mainly caused by the emission trend change in China. About half of the air mass trajectories are from northern China, and a quarter are from southern China. On the basis of cluster analysis, it was found that when air parcels moved from China, the concentrations of nss-sulfate, ammonium, and nitrate are the highest.
55 citations
TL;DR: In this article, the authors used ARIMA models for daily temporal analysis of the effect of land surface coverage (LSC) on PM10 concentrations in a high-altitude megacity.
52 citations
TL;DR: In this article, a source-oriented version of the Community Multiscale Air Quality (CMAQ) model was used to quantify contributions from nine regions to PM 2.5 in the Sichuan Basin.
Abstract: . The Sichuan Basin (SCB) is one of the regions suffering from severe air
pollution in China, but fewer studies have been conducted for this region
than for the more developed regions in eastern and northern China. In this study,
a source-oriented version of the Community Multiscale Air Quality (CMAQ)
model was used to quantify contributions from nine regions to PM 2.5
(i.e., particulate matter, PM, with an aerodynamic diameter less than 2.5 µ m) and its components in the 18 cities within the SCB in the winter
(December 2014 to February 2015) and summer (June to August 2015). In the
winter, citywide average PM 2.5 concentrations are 45–126 µ g m −3 , with 21 %–51 % and
39 %–66 % being
due to local and nonlocal emissions, respectively. In the summer,
15 %–45 % and 25 %–52 % of citywide average
PM 2.5 (14–31 µ g m −3 ) are due to local and
nonlocal emissions, respectively. Compared to primary PM (PPM), the
inter-region transport of secondary inorganic aerosols (SIA), including
ammonia, nitrate, and sulfate ions ( NH 4 + , NO 3 - , and
SO 4 2 - , respectively), and their gas-phase precursors are greater.
The region to the east of SCB (R7, including central and eastern China
and others) is the largest contributor outside the SCB, and it can
contribute approximately 80 % of PM 2.5 in the eastern, northeastern,
and southeastern rims of the SCB but only 10 % in other SCB regions in
both seasons. Under favorable transport conditions, regional transport of
air pollutants from R7 could account for up to 35–100 µ g m −3 of PM 2.5 in each of the SCB cities in the winter. This
study demonstrates that it is important to have joint emission control
efforts among cities within the SCB and regions to the east in order to
reduce PM 2.5 concentrations and prevent high PM 2.5 days for the
entire basin.
50 citations
Cites background from "Quantifying the influences of atmos..."
...…occurs in well-urbanized and/or industrialized cities associated with mountains and basins, such as Beijing, Chengdu, Xi’an, and Lanzhou in China (Chambers et al., 2015; Bei et al., 2017, 2018; Ning et al., 2018a, b); Mexico City, Salt Lake City, and Los Angeles in the North America (Langford…...
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TL;DR: In this article, the authors demonstrate the ability of atmospheric radon concentrations to reliably and unambiguously identify local and remote terrestrial influences on an air mass, and thereby the potential for alteration of trace gas composition by anthropogenic and biogenic processes.
Abstract: We demonstrate the ability of atmospheric radon concentrations to reliably and unambiguously identify local and remote terrestrial influences on an air mass, and thereby the potential for alteration of trace gas composition by anthropogenic and biogenic processes. Based on high accuracy (lower limit of detection 10-40 mBq m^(-3)), high temporal resolution (hourly) measurements of atmospheric radon concentration we describe, apply and evaluate a simple two-step method for identifying and characterising constituent mole fractions in baseline air. The technique involves selecting a radon-based threshold concentration to identify the ＂cleanest＂ (least terrestrially influenced) air masses, and then performing an outlier removal step based on the distribution of constituent mole fractions in the identified clean air masses. The efficacy of this baseline selection technique is tested at three contrasting WMO GAW stations: Cape Grim (a coastal low-altitude site), Mauna Loa (a remote high-altitude island site), and Jungfraujoch (a continental high-altitude site). At Cape Grim and Mauna Loa the two-step method is at least as effective as more complicated methods employed to characterise baseline conditions, some involving up to nine steps. While it is demonstrated that Jungfraujoch air masses rarely meet the baseline criteria of the more remote sites, a selection method based on a variable monthly radon threshold is shown to produce credible ＂near baseline＂ characteristics. The seasonal peak-to-peak amplitude of recent monthly baseline CO_2 mole fraction deviations from the long-term trend at Cape Grim, Mauna Loa and Jungfraujoch are estimated to be 1.1, 6.0 and 8.1 ppm, respectively.
47 citations
Cites background or methods or result from "Quantifying the influences of atmos..."
...…in continuous atmospheric radon measurement technology (e.g., Yver et al., 2011; Chambers et al., 2014; Pal et al., 2015; Williams and Chambers, 2015) have enabled far more stringent radon thresholds to be adopted (e.g., Chambers et al., 2015c), opening up new possibilities for baseline monitoring....
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...A radon-based technique for baseline characterisation at CGO, and its efficacy, has already been discussed by Chambers et al. (2015c)....
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...Chambers et al. (2015c) demonstrated that representative baseline mole fractions of constituent species can be retrieved from the CGO record by setting a radon concentration threshold of around 40 to 50 mBq m–3, and then performing a simple outlier removal on the remaining constituent mole…...
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...…a variety of transport and mixing studies, the fact that it is an unambiguous indicator of recent (2–3 week) contact of an air mass with land make radon an incredibly powerful tool for atmospheric baseline studies (e.g., Griffiths et al., 2014; Molloy and Galbally, 2014; Chambers et al., 2015c)....
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...The CGO dataset spans the 9-year period 2004–2013 (see also Chambers et al., 2015c), the MLO dataset spans the 7-year period 2004–2011 (see also Chambers et al., 2013), and the JFJ dataset spans the 2-year period 2010–2012 (see also Griffiths et al., 2014)....
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TL;DR: One year of radon, benzene and carbon monoxide (CO) concentrations were analyzed to characterise the combined influences of variations in traffic density and meteorological conditions on urban air quality in Bern, Switzerland as mentioned in this paper.
Abstract: One year of radon, benzene and carbon monoxide (CO) concentrations were analysed to characterise the combined influences of variations in traffic density and meteorological conditions on urban air quality in Bern, Switzerland. A recently developed radon-based stability categorisation technique was adapted to account for seasonal changes in day length and reduction in the local radon flux due to snow/ice cover and high soil moisture. Diurnal pollutant cycles were shown to result from an interplay between variations in surface emissions (traffic density), the depth of the nocturnal atmospheric mixing layer (dilution) and local horizontal advection of cleaner air from outside the central urban/industrial area of this small compact inland city. Substantial seasonal differences in the timing and duration of peak pollutant concentrations in the diurnal cycle were attributable to changes in day length and the switching to/from daylight-savings time in relation to traffic patterns. In summer, average peak benzene concentrations (0.62 ppb) occurred in the morning and remained above 0.5 ppb for 2 hours, whereas in winter average peak concentrations (0.85 ppb) occurred in the evening and remained above 0.5 ppb for 9 hours. Under stable conditions in winter, average peak benzene concentrations (1.1 ppb) were 120% higher than for well-mixed conditions (0.5 ppb). By comparison, summertime peak benzene concentrations increased by 53% from well-mixed (0.45 ppb) to stable nocturnal conditions (0.7 ppb). An idealised box model incorporating a simple advection term was used to derive a nocturnal mixing length scale based on radon, and then inverted to simulate diurnal benzene and CO emission variations at the city centre. This method effectively removes the influences of local horizontal advection and stability-related vertical dilution from the emissions signal, enabling a direct comparison with hourly traffic density. With the advection term calibrated appropriately, excellent results were obtained, with high regression coefficients in spring and summer for both benzene (r 2 ~0.90–0.96) and CO (r 2 ~0.88–0.98) in the two highest stability categories. Weaker regressions in winter likely indicate additional contributions from combustion sources unrelated to vehicular emissions. Average vehicular emissions during daylight hours were estimated to be around 0.503 (542) kg km −2 h −1 for benzene (CO) in the Bern city centre. Keywords: radon, air quality, urban, atmospheric stability, traffic density, vehicle emissions (Published: 6 September 2016) Citation: Tellus B 2016, 68, 30967, http://dx.doi.org/10.3402/tellusb.v68.30967
42 citations
Cites background or methods or result from "Quantifying the influences of atmos..."
...As described in Chambers et al. (2015a), the most ‘stable’ nocturnal conditions are typically followed by days with clear-sky, low-wind, anti-cyclonic conditions (i.e. fair weather), whereas near-neutral nights are typically fol- lowed by days with significant cloud cover and windy conditions (i.e.…...
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...These results are consistent with those of Quan et al. (2014), Grundstrom et al. (2015), Pitari et al. (2015), Sesana et al. (2006) and Chambers et al. (2011, 2015a), who each associated stable nocturnal conditions (including morning haze events) with wind speeds less than 1 1.5m s 1....
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...As part of our investigations, we adapted a recently developed radon-based technique for assessing nocturnal atmospheric stability (Chambers et al., 2015a, 2015b), in order to account for seasonal changes in day length and reductions in the local radon source function as a result of snow/ice cover…...
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...…the state of atmospheric stability (Pasquill and Smith, 1983; Perrino et al., 2001; Foken, 2006; Williams et al., 2013; Chambers et al., 2015a), here we employ near-surface measurements of the naturally occurring, radioactive atmospheric tracer Radon-222 (e.g. Chambers et al., 2015a, 2015b)....
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...Furthermore, the radon-based stability measures used here can be easily adjusted to suit the regional climatology (Chambers et al., 2015b)....
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References
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TL;DR: In this paper, the authors present the current state of understanding of the air pollution problems in China's mega cities and identify the immediate challenges to understanding and controlling air pollution in these densely populated areas.
2,164 citations
TL;DR: In this article, the authors developed a new emission inventory for Asia (Regional Emission inventory in ASia (REAS) Version 1.1) for the period 1980-2020.
Abstract: . We developed a new emission inventory for Asia (Regional Emission inventory in ASia (REAS) Version 1.1) for the period 1980–2020. REAS is the first inventory to integrate historical, present, and future emissions in Asia on the basis of a consistent methodology. We present here emissions in 2000, historical emissions for 1980–2003, and projected emissions for 2010 and 2020 of SO2, NOx, CO, NMVOC, black carbon (BC), and organic carbon (OC) from fuel combustion and industrial sources. Total energy consumption in Asia more than doubled between 1980 and 2003, causing a rapid growth in Asian emissions, by 28% for BC, 30% for OC, 64% for CO, 108% for NMVOC, 119% for SO2, and 176% for NOx. In particular, Chinese NOx emissions showed a marked increase of 280% over 1980 levels, and growth in emissions since 2000 has been extremely high. These increases in China were mainly caused by increases in coal combustion in the power plants and industrial sectors. NMVOC emissions also rapidly increased because of growth in the use of automobiles, solvents, and paints. By contrast, BC, OC, and CO emissions in China showed decreasing trends from 1996 to 2000 because of a reduction in the use of biofuels and coal in the domestic and industry sectors. However, since 2000, Chinese emissions of these species have begun to increase. Thus, the emissions of air pollutants in Asian countries (especially China) showed large temporal variations from 1980–2003. Future emissions in 2010 and 2020 in Asian countries were projected by emission scenarios and from emissions in 2000. For China, we developed three emission scenarios: PSC (policy success case), REF (reference case), and PFC (policy failure case). In the 2020 REF scenario, Asian total emissions of SO2, NOx, and NMVOC were projected to increase substantially by 22%, 44%, and 99%, respectively, over 2000 levels. The 2020 REF scenario showed a modest increase in CO (12%), a lesser increase in BC (1%), and a slight decrease in OC (−5%) compared with 2000 levels. However, it should be noted that Asian total emissions are strongly influenced by the emission scenarios for China.
1,388 citations
TL;DR: The International Global Atmospheric Chemistry Program (IGAC) has conducted a series of Aerosol Characterization Experiments (ACE) that integrate in situ measurements, satellite observations, and models to reduce the uncertainty in calculations of the climate forcing due to aerosol particles as discussed by the authors.
Abstract: [1] The International Global Atmospheric Chemistry Program (IGAC) has conducted a series of Aerosol Characterization Experiments (ACE) that integrate in situ measurements, satellite observations, and models to reduce the uncertainty in calculations of the climate forcing due to aerosol particles. ACE-Asia, the fourth in this series of experiments, consisted of two focused components: (1) An intensive field study that sought to quantify the spatial and vertical distribution of aerosol concentrations and properties, the processes controlling their formation, evolution, and fate, and the column-integrated radiative effect of the aerosol (late March through May 2001). (2) A longer-term network of ground stations that used in situ and column-integrated measurements to quantify the chemical, physical, and optical properties of aerosols in the ACE-Asia study area and to assess their spatial and temporal (seasonal and interannual) variability (2000–2003). The approach of the ACE-Asia science team was to make simultaneous measurements of aerosol chemical, physical, and optical properties and their radiative impacts in a variety of air masses, often coordinated with satellite overpasses. Three aircraft, two research ships, a network of lidars, and many surface sites gathered data on Asian aerosols. Chemical transport models (CTMs) were integrated into the program from the start, being used in a forecast mode during the intensive observation period to identify promising areas for airborne and ship observations and then later as tools for integrating observations. The testing and improvement of a wide range of aerosol models (including microphysical, radiative transfer, CTM, and global climate models) was one important way in which we assessed our understanding of the properties and controlling processes of Asian aerosols. We describe here the scientific goals and objectives of the ACE-Asia experiment, its observational strategies, the types of observations made by the mobile platforms and stationary sites, the models that will integrate our understanding of the climatic effect of aerosol particles, and the types of data that have been generated. Eight scientific questions focus the discussion. The intensive observations took place during a season of unusually heavy dust, so we have a large suite of observations of dust and its interaction with air pollutants. Further information about ACE-Asia can be found on the project Web site at http://saga.pmel.noaa.gov/aceasia/.
855 citations
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..., 2014) and beyond (e.g. Jo and Kim, 2013; Begum et al., 2011; Ohara et al., 2007; Park et al., 2004; Huebert et al., 2003; Guttikunda et al., 2001)....
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TL;DR: A number of epidemiological studies on air pollution and population health have been conducted in China, using time-series, case-crossover, cross-sectional, cohort, panel or intervention designs.
580 citations