Recent increase of surface particulate matter concentrations in the Seoul Metropolitan Area, Korea

Kim, Hyun Cheol; Kim, Soontae; Kim, Byeong-Uk; Jin, Chun‐Sil; Hong, Song‐You; Park, Rokjin J.; Son, Seok‐Woo; Bae, Changhan; Bae, Minah; Song, Chang‐Keun; Stein, Ariel

doi:10.1038/s41598-017-05092-8

Cited by 134 publications

(97 citation statements)

References 56 publications

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“…Improvements in the PM 2.5 achievement ratio result from complex interactions between Japanese and Chinese emission-reduction measures, and it is not yet clear which factor has a greater contribution. This lack of clarity arises because most PM 2.5 studies are focused on an individual country, and quantitative evaluations or correlation analyses of the impacts of environmental improvement on downwind regions (beyond national borders) have rarely been published [18][19][20][21] . Studying the relationship between decreased PM 2.5 concentrations in China and its downwind regions and clarifying quantitative source/receptor (S/R) relationships are essential for establishing better environmental policies.Remote island observations of aerosol chemical compositions off the west coast of Japan (eastern edge of the East China Sea) indicate that sulfate concentrations have decreased significantly, consistent with the decrease in SO 2 emissions in China.…”

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confidence: 99%

Paradigm shift in aerosol chemical composition over regions downwind of China

Uno

Wang

Itahashi

et al. 2020

Sci Rep

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A rapid decrease in pM 2.5 concentrations in china has been observed in response to the enactment of strong emission control policies. From 2012 to 2017, total emissions of SO 2 and no x from china decreased by approximately 63% and 24%, respectively. Simultaneously, decreases in the PM 2.5 concentration in Japan have been observed since 2014, and the proportion of stations that satisfy the pM 2.5 environmental standard (daily, 35 µg/m 3 ; annual average, 15 µg/m 3 ) increased from 37.8% in fiscal year (FY) 2014 (April 2014 to March 2015) to 89.9% in FY 2017. However, the quantitative relationship between the pM 2.5 improvement in china and the pM 2.5 concentration in downwind regions is not well understood. Here, we (1) quantitatively evaluate the impacts of Chinese environmental improvements on downwind areas using source/receptor analysis with a chemical transport model, and (2) show that these rapid emissions reductions improved pM 2.5 concentrations both in china and its downwind regions, but the difference between SO 2 and no x reduction rates led to greater production of nitrates (e.g., NH 4 no 3 ) due to a chemical imbalance in the ammonia-nitric acid-sulfuric acid-water system. Observations from a clean remote island in western Japan and numerical modeling confirmed this paradigm shift.The long-range trans-boundary transport behavior of pollutants in East Asia is an important environmental issue due to frequent outflows of heavy pollution. Among pollutants, PM 2.5 (particulate matter less than 2.5 µm in diameter) poses serious human health risks, including lung cancer, respiratory disease, and asthma, particularly over China and its downwind regions 1-5 . Serious PM 2.5 pollution has been observed in the northern China region since the early 2010s. To reduce this pollution, China has implemented active clean air policies in recent years (e.g., the Action Plan for Prevention and Control of Air Pollution, enacted in September 2013). These plans include the phasing out of outdated industrial capacity, small high-emission factories, and small coal-fired industrial boilers, as well as the strengthening of emission standards for power plants, industries, and vehicles, and the replacement of residential coal use with electricity and natural gas 6,7 . These strong emission-reduction policies in China have led to a successful reduction in PM 2.5 concentration (e.g., PM 2.5 concentrations decreased from 102 µg/m 3 in 2013 to 43 µg/m 3 in 2019, as observed at the U.S. embassy in Beijing). Rapid reductions in SO 2 and NO x emissions were also confirmed using environmental satellite data 8 and bottom-up emissions inventory studies 1 . MODIS AOD (aerosol optical depth) data revealed that there has been a consistent trend of year-to-year decreases in China and its downwind regions. The chemical composition of PM 2.5 also changed significantly over China, with especially large decreases in levels of organic matter, mineral components, and sulfate aerosols 9 . Studies have suggested that emission control has a dominant e...

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confidence: 99%

Paradigm shift in aerosol chemical composition over regions downwind of China

Uno

Wang

Itahashi

et al. 2020

Sci Rep

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“…The SSA emission parameterization of Monahan et al (1986) is commonly used to model sea-salt emissions of coarse particles (e.g. Sartelet et al, 2012;Solazzo et al, 2017;Kim et al, 2017). However, the strong non-linearity of the source function versus wind speed (power law with an exponent of 3.41) may lead to an overestimation of emissions at high-speed regimes, as suggested by Guelle et al 15 (2001) and Witek et al (2007).…”

Section: Introductionmentioning

confidence: 88%

Aerosol sources in the western Mediterranean during summertime: A model-based approach

Chrit¹,

Sartelet²,

Sciare³

et al. 2018

Preprint

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Abstract.In the framework of ChArMEx (the Chemistry-Aerosol Mediterranean Experiment), the air-quality model Polyphemus is used to understand the sources of inorganic and organic particles in the western Mediterranean and to evaluate the uncertainties linked to the model parameters (meteorological fields, anthropogenic and sea-salt emissions, hypotheses related to the model representation of condensation/evaporation). The model is evaluated by comparisons to in-situ aerosol measurements 5 performed during three consecutive summers (2012, 2013 and 2014). The model-to-measurement comparisons concern the concentrations of PM 10 , PM 1 , Organic Matter in PM 1 (OM P M1 ) and inorganic aerosol concentrations monitored at a remote site (Ersa) in Corsica Island, as well as during airborne measurements performed above the western Mediterranean Sea. Organic particles are mostly from biogenic origin. The model parameterization of sea-salt emissions has shown to strongly influence the concentrations of all particulate species (PM 10 , PM 1 , OM P M1 and inorganic concentrations). Although the emission of 10 organic matter by the sea has shown to be low, organic concentrations are influenced by sea-salt emissions, because they provide a mass onto which gaseous hydrophilic organic compound can condense. PM 10 , PM 1 , OM P M1 are also very sensitive to meteorology, because it affects not only the transport of pollutants, but also natural emissions (biogenic and sea salt). To avoid large and unrealistic sea-salt concentrations, a parameterization with an adequate wind-speed power law is chosen. Sulfate is shown to be strongly influenced by anthropogenic (ship) emissions. PM 10 , PM 1 , OM 1 and sulfate concentrations are better 15 described using the emission inventory with the best spatial description of ships emissions (EDGAR-HTAP). However, this is not true for nitrate, ammonium and chloride concentrations, which are very dependent on the hypotheses used in the model for condensation/evaporation. Model simulations show that sea-salt aerosols above the sea are not mixed with background transported aerosols. Taking into account the mixing state of particles with a dynamic approach of condensation/evaporation may be necessary to accurately represent inorganic aerosol concentrations.

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“…To overcome the aforementioned limitations and to perform computationally efficient contribution estimation, we used a nested modeling domain in this study ( Figure 1): an outer domain with a 27-km horizontal grid resolution to cover major emission regions in Northeast Asia and an inner domain with a 9-km horizontal grid resolution over the Korean Peninsula. For the temporal scale, we note that recent meteorological changes in Northeast Asia had affected air quality in the region [13,14]. Therefore, we attempted to account for the effect of interannual variability of meteorology on the estimated contributions by conducting 8-year-long (2010-2017) simulations in this study.…”

Section: The Modeling Domain and Study Periodmentioning

confidence: 99%

“…Over the modeling period, the model underestimated the 2-m temperatures by 0.4 • C on average (the correlation coefficient (R) between the modeled and observed values was 1.0), and the normalized mean bias (NMB) was −4% to 1.3% and R was 0.95 to 0.99 for the seasonal analysis of the 2-m temperatures. Moreover, the model overestimated the 10-m wind speeds by 0.5 m/s on average (R = 0.8), which likely resulted in the faster transport of air pollutants in the model [13,31]. Especially, the 10-m wind speeds were overestimated in the winter by up to 0.8 m/s.…”

Section: Performance Evaluation Of the Wrf Simulationmentioning

confidence: 99%

A Multiscale Tiered Approach to Quantify Contributions: A Case Study of PM2.5 in South Korea During 2010–2017

Bae

Kim

et al. 2020

Atmosphere

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We estimated long-term foreign contributions to the particulate matter of 2.5 μm or less in diameter (PM2.5) concentrations in South Korea with a set of air quality simulations. The Weather Research and Forecasting (WRF)-Sparse Matrix Operator Kernel Emissions (SMOKE)-Community Multiscale Air Quality (CMAQ) modeling system was used to simulate the base and sensitivity case after a 50% reduction of foreign emissions. The effects of horizontal modeling grid resolutions (27- and 9-km) was also investigated. For this study, we chose PM2.5 in South Korea during 2010–2017 for the case study and emissions from China as a representative foreign source. The 9-km simulation results show that the 8-year average contribution of the Chinese emissions in 17 provinces ranged from 40–65%, which is ~4% lower than that from the 27-km simulation for the high-tier government segments (particularly prominent in coastal areas). However, for the same comparison for low-tier government segments (i.e., 250 prefectures), the 9-km simulation presented lowered the foreign contribution by up to 10% compared to that from the 27-km simulation. Based on our study results, we recommend using high-resolution modeling results for regional contribution analyses to develop an air quality action plan as the receptor coverage decreases.

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Recent increase of surface particulate matter concentrations in the Seoul Metropolitan Area, Korea

Cited by 134 publications

References 56 publications

Paradigm shift in aerosol chemical composition over regions downwind of China

Paradigm shift in aerosol chemical composition over regions downwind of China

Aerosol sources in the western Mediterranean during summertime: A model-based approach

A Multiscale Tiered Approach to Quantify Contributions: A Case Study of PM2.5 in South Korea During 2010–2017

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