Nitrogen oxides (NO_X) in the atmosphere cause oxidation reactions with photochemical radicals and volatile organic compounds, leading to the accumulation of ozone (O₃). NO_X constitutes a significant portion of the NO_y composition, with nitrous acid (HONO) and nitric acid (HNO₃) following. HONO plays a crucial role in the reaction cycle of NO_X and hydrogen oxides. The majority of HNO₃ reduction mechanisms result from aerosolization through heterogeneous reactions, having adverse effects on humans and plants by increasing secondary aerosol concentrations in the atmosphere. The investigation of the formation and conversion mechanisms of HONO and HNO₃ is important; however, research in this area is currently lacking. In this study, we observed HONO, HNO₃, and their precursor gases were observed in the atmosphere using parallel-plate diffusion scrubber-ion chromatography. A 0-D box model simulated the compositional distribution of NO_y in the atmosphere. The formation reactions and conversion mechanisms of HONO and HNO₃ were quantified using reaction equations and reaction coefficients. Among the various mechanisms, dominant mechanisms were identified, suggesting their importance. According to the calculation results, the produce of HONO was predominantly attributed to heterogeneous reactions, excluding an unknown source. The sink processes were mainly governed by photolysis during daytime and reactions with OH radicals during nighttime. HNO₃ showed dominance in its production from N₂O₅, and in its conversion mechanisms primarily involving aerosolization and deposition.

Volatile organic compounds (VOCs) are one of significant contributors to air pollution and have profound effects on human health and the environment. This study introduces a detailed analysis of VOC emissions from various industries within an industrial complex using a high-resolution measurement instrument. This study aimed to identify the VOC profiles and their concentrations across 12 industries. Sampling was conducted across 99 facilities in an industrial complex in South Korea, and VOC analysis was performed based on measurement data using a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS). The results indicated that the emission of oxygenated VOCs (OVOCs) was dominant in most industries. Aromatic hydrocarbons were also dominant in most industries, except in screen printing (SP), lubricating oil and grease manufacturing (LOG), and industrial laundry services (ILS) industries. Chlorinated VOCs (Cl-VOCs) showed a relatively higher level in the metal plating (MP) industry than those in other industries and nitrogen-containing VOCs (N-VOCs) showed high levels in general paints and similar product manufacturing (PNT), MP, and ILS industries, respectively. The gravure printing industry was identified as the highest emitter of VOCs, with the highest daily emissions reaching 5934 mg day⁻¹, primarily consisting of ethyl acetate, toluene, butyl acetate, and propene. The findings suggest that the VOC emissions from the gravure printing and plastic synthetic leather industries should be primarily reduced, and it would be the most cost-effective approach to improving air quality. This study can provide the fundamental data for developing effective reduction technologies and policies of VOC, ultimately contributing to enhanced atmospheric models and regulatory measures.

Hybrid receptor models overestimate the contribution of background areas (no specific emission sources), like the Yellow Sea in Korea. This study aimed to improve model performances using Advanced Concentration Emission and Retention Time Weighted Trajectory (ACERWT). ACERWT was combined with a positive matrix factorization (PMF), back trajectory, and Regional Emission Inventory in Asia (REAS). The PMF receptor model used one year of data from Korea’s Central Air Environment Research Center. In the PMF receptor model, eight sources (dust/soil, secondary nitrate, biomass burning, vehicles, secondary sulfate, industry, coal combustion and sea salt) influenced PM_2.5 pollution at the receptor site (Daejeon, Korea). Secondary sulfate was the most dominant source, followed by secondary nitrate and vehicle sources. ACERWT results showed high contributions from China, Japan, and Korean regions, while the contribution from the Yellow Sea was significantly lower. Several regions, such as the eastern and south-eastern areas of China, the southern area of Taiwan, the western area of Tokyo, and the central area of Korea, showed high contributions due to large-scale emission facilities and industrial complexes. In this study, the ACERWT model significantly improved its performance regarding regional contributions to PM_2.5 pollution at the receptor site.

To establish and implement effective policies for controlling fine particle matters (PM_2.5), which is associated with high-risk diseases, continuous research on identifying PM_2.5 sources was conducted. This study utilized the positive matrix factorization (PMF) receptor model to estimate the sources and characteristics of PM_2.5 between Baengnyeong Island (BNI) and the Seoul Metropolitan Area (SMA). We conducted PMF modeling and backward trajectory analysis using the data on PM_2.5 and its components collected from 2020 to 2021 at the Air quality Research Centers (ARC). The PMF modeling identified nine pollution sources in both BNI and the SMA, including secondary sulfate, secondary nitrate, vehicles, biomass burning, dust, industry, sea salt particles, coal combustion, and oil combustion. Secondary particulate matter, vehicles, and biomass burning were found to be major contributors to PM_2.5 concentrations in both regions. A backward trajectory analysis indicated that air masses, passing through BNI to the SMA, showed higher concentrations and contributions of ammonium nitrate, vehicles, and biomass burning in the SMA site compared to BNI site. These findings suggest that controlling nitrogen oxides (NOx) and ammonia emissions in the SMA, as well as monitoring the intermediate products that form aerosols, such as HNO₃, are needed.

Ammonia is one of the precursor gases in the formation of particulate matter (PM) that reacts with nitrogen oxides and sulfur oxides in the atmosphere. Based on the Clean Air Policy Support System (CAPSS) of Korea, the annual ammonia emissions amounted to 261,207 tons in 2020 and the agricultural source (manure management sector) contributes the highest proportion of the ammonia inventory. However, the methodology for the study of ammonia emissions in Korea has some limitations regarding the representativeness of the sites selected and the reliability of the measurement method. In this study, we aimed to recalculate the ammonia emissions from the livestock industry in Korea using the UK’s estimation method, which uses the life cycle assessment of livestock manure. Three major animal types, i.e., cattle (beef cattle and dairy cows), pigs and chickens, and three major processes based on the manure flow, i.e., housing, manure storage and treatment and land application processes, were considered. The total ammonia emissions were estimated to be approximately 33% higher than the official ammonia emissions stated by the CAPSS. For the manure flow, the ammonia emissions were the highest from land application processes. The ammonia emissions from dairy cow and poultry manure were much higher than those stated by the CAPSS, while the emissions from beef cattle and pig manure showed similar levels. The methodology used in this study can offer an alternative approach to the ammonia emission estimation of the manure management sector in the agriculture industry of Korea. Korean emission factors based on the manure flow should be developed and applied in the future.

Particulate and gaseous polycyclic aromatic hydrocarbon (PAHs) samples (n = 108) were measured every six days from January to December 2022 at a representative point in the Korean Banwol National Industrial Complex. The measurement results revealed that the concentration of particulate Σ18 PAHs was 7.92 ± 4.04 ng/Sm³ in winter, 1.83 ± 1.99 ng/Sm³ in spring, 1.43 ± 0.95 ng/Sm³ in summer, and 2.58 ± 2.14 ng/Sm³ in autumn. The concentration of gaseous Σ18 PAHs was 3.32 ± 3.72 ng/Sm³ in winter, 6.34 ± 5.95 ng/Sm³ in spring, 8.33 ± 8.13 ng/Sm³ in summer, and 3.88 ± 1.71 ng/Sm³ in autumn. The results of the correlation analysis showed that particulate PAHs have positive relationships with PM₁₀ and PM_2.5 and negative relationships with temperature and O₃. The diagnostic ratio and PAHs component slope showed that the emission source characteristics of the Banwol National Industrial Complex were dominated by biomass coal combustion over four seasons; however, the influence of petroleum combustion (automobile emissions) was not negligible. As for coal combustion, bituminous coal was the most influential, and lignite was relevant in summer and autumn.