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Abstract This study aimed to identify the factors causing NH3 emissions in the South Korean Peninsula and West Sea region. To analyze the trends of NH3 and other air pollutants, such as NOx, CO, and NR-PM1, we collected samples from six supersites across the peninsula, a roadside in Seoul, and the West Sea over different sampling periods, ranging from 1 month to 1 year. The highest NH3 concentrations were found at rural areas, ascribed to agricultural activities, particularly NH4NO3 decomposition at high summer temperatures. Areas with low population densities recorded the lowest NH3 concentrations, attributed to the lack of anthropogenic activities. A roadside field experiment confirmed the close link between ambient NH3 and vehicle emissions in urban regions by showing a strong correlation between CO and NOx concentrations and that of NH3. Moreover, we examined oceanic emissions near the eastern coast of South Korea in the West Sea. Long-range transportation studies confirmed that most of the pollutants (NH3, CO, and PM1) were transported by wind from the northeastern region of China. A maritime origin study showed that oceanic emissions and NH4NO3 decomposition in the atmosphere owing to high temperatures were the causing NH3 pollution. These findings provided valuable insights into the emission sources of NH3 in primary air pollutants in South Korea, highlighting the contributions of land-based and oceanic sources. Our study can help inform policymakers and stakeholders for developing effective regional air pollution control strategies.

Abstract We conducted spatiotemporal assessments of ozone in South Korea from 1990–2020 to evaluate trends and compare changes in compliance based on South Korean, US, and EU standards. Observational data from nationwide air-quality monitoring stations were collected and converted to the maximum daily 8 hr ozone average (MDA8O3). Seasonal ozone variations displayed an overall increase across most of South Korea and a noticeably high rate of 0.86 ppbv/yr in Seoul, with an even higher rate 1.2 ppbv/yr for the fourth-highest MDA8O3. Recent air-quality regulations to reduce NOx emissions have been estimated to weaken NO titration effects, leading to higher ozone levels for VOC-limited urban areas in South Korea while decreasing ozone concentrations elsewhere. In recent years, nearly all monitoring stations have exceeded the South Korean MDA8O3 standard, leading to debate regarding the adequacy of current standards for monitoring changes in nonattainment. Comparison with EU and US standards showed that implementing these could significantly lower nonattainment events due to the easing of target threshold values by either percentile or concentration values. Relative distances in nonattainment percentages between South Korean and other standards indicated that the EU ozone guideline was most suitable for tracing recent ozone changes not apparent when using the South Korean or US standards.

As the observational constraints of SO2 become a limiting factor for emission inventory and regional and global transport model validations, we present an airborne SO2 observational suite integrated on Beechcraft 1900D (B1900D) operated by Hanseo University. A chemical ionization mass spectrometry (CIMS) technique using SF6- ion chemistry is used to take advantage of fast response (

This study characterized the water-soluble organic carbon (WSOC) and ionic components of PM2.5 (particles less than 2.5 μm in diameter) from April to June 2016, at Baengnyeong Island The study utilized a particle-into-liquid sampler (PILS) coupled with a total organic carbon (TOC) analyzer and ion chromatography (PILS-TOC-IC). The PM2.5 mean concentration in this study was 23.8±16.7 μg m-3, and the mean of WSOC concentration was 1.6±1.5 μg m-3. Ionic compounds increased by 3.8% in the period in which the air quality standard of PM2.5 (35 μg m-3) was exceeded because the concentration of ionic components increased due to generation by chemical reactions and emissions from a primary source in a nearby urban area. The wind direction and speed were mostly in the northwest and southwest directions and the higher concentration of PM2.5 was also shown in the same directions. In comparison with the previous study, the WSOC/OC ratio was 0.5±0.3 in Baengnyeong Island, which was higher than that at roadside and urban sites and lower than at the background site (Sweden, Aspvreten). It was considered that insoluble OC constituted a major proportion of primary OC that was emitted in urban areas, and the higher WSOC/OC ratios of rural and background sites were affected by inflow. The ratio of nitrate and sulfate in Baengnyeong Island was lower than urban areas in China in other studies, because of emitted aerosols from coal combustion or vehicle emission. The results indicate that Baengnyeong Island was affected by formation of secondary aerosols by chemical reactions and inflow from China as well as domestic emissions. The slope of H+Aersol/SO42- in Baengnyeong Island was 0.079, which was a result of neutralized particle acidity in ambient air. The molar ratio of nitrate and ammonium with sulfate in Baengnyeong Island showed ammonium-rich conditions because ammonium nitrate was increased to homogeneous reaction of ammonia and nitric acid in the gas-phase.

To improve the understanding of secondary organic aerosol (SOA) formation from the photo-oxidation of anthropogenic and biogenic precursors at the regional background station on Baengnyeong Island, Korea, gas phase and aerosol chemistries were investigated using the Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS) and the Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS), respectively. HR-ToF-AMS measured fine particles (PM1 diameter of particle matter less than 1 μm) at a 6-minute time resolution from February to November 2012, while PTR-ToF-MS was deployed during an intensive period from September 21 to 29, 2012. The one-minute time-resolution and high mass resolution (up to 4000 m Δm-1) data from the PTR-ToF-MS provided the basis for calculations of the concentrations of anthropogenic and biogenic volatile organic compounds (BVOCs) including oxygenated VOCs (OVOCs). The dominant BVOCs from the site are isoprene (0.23 ppb), dimethyl sulphide (DMS, 0.20 ppb), and monoterpenes (0.38 ppb). Toluene (0.45 ppb) and benzene (0.32 ppb) accounted for the majority of anthropogenic VOCs (AVOCs). OVOCs including acetone (3.98 ppb), acetaldehyde (2.67 ppb), acetic acid (1.68 ppb), and formic acid (2.24 ppb) were measured. The OVOCs comprise approximately 75% of total measured VOCs, suggesting the occurrence of strong oxidation processes and/or long-range transported at the site. A strong photochemical aging and oxidation of the atmospheric pollutants were also observed in aerosol measured by HR-ToF-AMS, whereby a high f44 : f43 value is shown for organic aerosols (OAs); however, relatively low f44 : f43 values were observed when high concentrations of BVOCs and AVOCs were available, providing evidence of the formation of SOA from VOC precursors at the site. Overall, the results of this study revealed several different SOA formation mechanisms, and new particle formation and particle growth events were identified using the powerful tools scanning mobility particle sizer (SMPS), PTR-ToF-MS, and HR-ToF-AMS.

In the past several decades, biofuels have emerged as candidates to help mitigate the issues of global warming, fossil fuel depletion and, in some cases, atmospheric pollution. To date, the only biofuels that have achieved any significant penetration in the global transportation sector are ethanol and biodiesel. The global consumption of biodiesel was rapidly increased from 2005. The goal of this study was to examine the chemical composition on particulate pollutant emissions from a diesel engine operating on several different biodiesels. Tests were performed on non-road diesel engine. Experiments were performed on 5 different fuel blends at 2 different engine loading conditions (50% and 75%). 5 different fuel blends were ultra-low sulfur diesel (ULSD, 100%), soy biodiesel (Blend 20% and Blend 100%) and canola biodiesel (Blend 20% and Blend 100%). The chemical properties of particulate pollutants were characterized using an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS). Organic matter and nitrate were generally the most abundant aerosol components and exhibited maximum concentration of 1207 μg/m3 and 30 μg/m3, respectively. On average, the oxidized fragment families (CxHyO1+, and CxHyOz+) account for ~13% of the three family sum, while ~87% comes from the CxHy+ family. The two peaks of C2H3O2 (m/z 59.01) and C3H7O (m/z 59.04) located at approximately m/z 59 could be used to identify atmospheric particulate matter directly to biodiesel exhaust, as distinguished from that created by petroleum diesel in the AMS data.