Fine particulate matter (PM) release is regulated by environmental policies in most countries. This study investigated long–term trends in the mass extinction efficiency (Qe) of aerosols in Northeast Asia. For this purpose, the Qe was calculated using visibility, PM2.5 recorded between 2015 and 2020, and PM10 recorded between 2001 and 2020 at eight Korean sites. The Qe of PM10 (Qe,10) showed an increasing trend with 0.06~0.22 (m2/g)/yr in seven cities except for Jeju. The Qe of PM2.5 (Qe,2.5) also showed an increasing trend with 0.28–2.47 (m2/g)/yr in all cities. In this study, PM10 and PM2.5, were divided into low, moderate, and high concentrations, and the Qe value change by year was examined. Qe,10 showed a tendency to decrease at low concentrations (19–21 μg/m3). However, at moderate (69–71 μg/m3) and high concentrations (139–141 μg/m3), Qe,10 increased in most regions. Qe,2.5 showed an increasing trend at low concentration (9–11 μg/m3), moderate concentration (29–31 μg/m3), and high concentration (69–71 μg/m3), except for Suwon and Pohang, where data were insufficient for analysis. Both Qe,10 and Qe,2.5 showed an increasing trend. The increase in Qe indicated that the visibility-impairing effect of PM can increase even if the same concentration of PM is present. The visibility-impairing effects of PM vary based on the composition, size and other characteristics of the particles in the atmosphere at a given point in time and not simply the quantity of particles. This means that reducing the quantity of particles does not reliably produce a proportionate improvement in visibility. Air quality policies must take the variable nature of PM particles and their effect on visibility into account so that more consistent improvements in air quality can be achieved.
Black carbon (BC) absorption aerosol optical depth (AAODBC) defines the contribution of BC in light absorption and is retrievable using sun/sky radiometer measurements provided by Aerosol Robotic Network (AERONET) inversion products. In this study, we utilized AERONET-retrieved depolarization ratio (DPR, δp), single scattering albedo (SSA, ω), and Ångström Exponent (AE, å) of version 3 level 2.0 products as indicators to estimate the contribution of BC to the absorbing fractions of AOD. We applied our methodology to the AERONET sites, including North and South America, Europe, East Asia, Africa, India, and the Middle East, during 2000–2018. The long-term AAODBC showed a downward tendency over Sao Paulo (−0.001 year−1), Thessaloniki (−0.0004 year−1), Beijing (−0.001 year−1), Seoul (−0.0015 year−1), and Cape Verde (−0.0009 year−1) with the highest values over the populous sites. This declining tendency in AAODBC can be attributable to the successful emission control policies over these sites, particularly in Europe, America, and China. The AAODBC at the Beijing, Sao Paulo, Mexico City, and the Indian sites showed a clear seasonality indicating the notable role of residential heating in BC emissions over these sites during winter. We found a higher correlation between AAODBC and fine mode AOD at 440 nm at all sites except for Beijing. High pollution episodes, BC emission from different sources, and aggregation properties seem to be the main drivers of higher AAODBC correlation with coarse particles over Beijing.
<p>In the case of large industrial complexes, there are state management equipment to monitor pollutants emitted from chimneys, but there are undetected sources of pollution, such as leaks during processes, leaks from pipes, and leaks from unsealed warehouses, except for chimneys. In this study, mobile observation was conducted using SOF, Sky DOAS, in-situ MeDOAS, and MeFTIR equipment. The observation method used in this study is fence line monitoring, which surrounds a large factory area and observes both the upwind and downwind sides. method of observation. The observation site was conducted in July and August 2021 at the Yeosu Industrial Complex located in Yeosu, Jeollanam-do, South Korea, one of the three largest industrial complexes in South Korea. In order to find out whether and the extent of leakage, four areas where Telemonitoring System(TMS), a chimney measuring device managed by the Korea Environment Corporation, exist were designated as observation sites. The results observed for the same period of time were compared for SO<sub>2 </sub>and NO<sub>2</sub>, which are substances with overlapping measurement items of mobile monitoring vehicle(MMV) and TMS. Although a direct comparison was not possible because the MMV expresses the emission per hour and the TMS expresses the emission concentration, it was confirmed that leaks that were not captured by the TMS on a specific date appeared as a result of the MMV measurement. This study confirmed that even in industrial complexes where TMS is installed for management purposes, air pollution and economic losses due to leaks can be reduced if fan line monitoring is conducted to detect unexpected leaks.</p> <p>&#160;</p> <p><strong>acknowledgment</strong></p> <p>This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. 2018R1D1A3B07048047)</p> <div data-hjsonver="1.0" data-jsonlen="10375">&#160;</div>
<p>The mass extinction efficiency(MEE), which indicates the degree of aerosol extinction(scatter and absorption) per unit PM mass concentration, is an important factor in converting optical concentration into mass concentration. Because its value varies depending on the particles' size and composition, which are particles' characteristics. In this study, the extinction coefficients of coarse and fine particles were calculated using the LiDAR data of Seoul observed by NIES(Japan's National Institute of Environmental Studies) and the visibility data of Seoul observed by the Korea Meteorological Administration. In the case of lidar data, two wavelengths (532nm, 1064nm) measured by lidar were used to calculate extinction coefficients, and the wavelength of 532 nm (532P and 532S) were used to classify extinction coefficients into coarse particles(PM10-2.5) and fine particles(PM2.5). In the case of visibility data, the PM10 and PM2.5 extinction coefficients were calculated using the equation of Koschmieder (1924) and Cheng et al. (2017). The PM10, PM10-2.5, and PM2.5 respective MEE were calculated using Seoul data of PM10 and PM2.5 at the same time provided by the Korea Environment Corporation. The relative humidity data provided by the Korea Meteorological Administration were divided into seven sections less than 40%, 40~49%, 50~59%, 60~69%, 70~79%, 80~89%, and 90~100%. According to relative humidity, this study examined the change of the calculated MEE. This study analyzes the effect of relative humidity on the Hygroscopic Growth of PM10, PM10-2.5, and PM2.5.</p><div>&#160;</div>
<p>The refractive index (RI) of aerosol is an important parameter that reflects the scattering and absorption capacity of aerosol and is widely used in atmospheric models and remote sensing studies. It depends on several properties such as chemical species, moisture content, etc. RI is usually obtained by the chemical method using a volume mixing ratio of known chemicals and by the optical method based on extinction, scattering and/or absorption coefficient using Mie theory. However, these methods are complicated and are mainly for singular particles. In this study, we tried to make a simple method to estimate RI by measuring the extinction coefficient from camera images and size distribution from the optical particle counter (OPC). We used the wavelength of Red-Green-Blue color as 597, 534, and 459 nm to calculate the extinction coefficient and the number size distribution to retrieve the volume size distribution obtained by OPC. The volume size distribution is expressed by six parameters of two gaussian graphs for fine and coarse-mode particles. We got the volume, median radius, and standard deviation of fine and coarse aerosol peaks. The measurement site was the port area in Busan, Korea. We sometimes discovered the emission of particles but mainly measured for clear days. We effectively retrieved six parameters determining the volume size distribution of ambient aerosols and tried to inverse RI as total, fine, and coarse particles using the nonlinear optimization method. We mainly considered the scattering effects of ambient aerosols, so we focused on the real part of RI. The retrieved RI was from 1.27 to 1.50 and showed different values on fine- and coarse-mode size particles. The results were lower than other RI measurement studies, so we need to validate more. However, we identified the possibility of retrieving the RI of aerosols using the known size distribution retrieved from OPC and the three-color extinctions from the camera.</p>
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