A Long Term Trend of Gaseous and Particulate Acid/Base Species and Effects of Ammonia Reduction on Nitrate Contained in PM~2018

High efficiency of nitric acid controls in alleviating particulate nitrate in livestock and urban areas in South Korea

“…Thus, high NH 3 levels have been reported in the summer. 8,27,48 However, the atmospheric NH 3 concentration was signicantly higher in the winter (124.6 ppb) than in the summer (76.0 ppb) (Table S1 and Fig. S4D †).…”

“…PM 1.0 and HNO 3 were collected using a two-stage sequential air sampler (APM Engineering, PMS-114, Korea) which has been widely used. 26,27 The sequential air sampler consisted of two stages for collection of PM 1.0 on a Teon lter (PTFE, 66155, PALL, USA) at the rst stage, and of HNO 3 on a nylon lter (Nylon, 1213776, GVS, USA) at the second stage. It was operated at a ow rate of 16.7 L min −1 for 24 h from 00:00 am to 00:00 am the following day during the measurement period.…”

“…The atmospheric NH 3 concentration in the populated livestock area was signicantly (2-35 times) higher than that in other livestock and urban areas listed in Table 1. 8,27,[41][42][43][44][45] This is because of livestock activities, open manure storage facilities, and livestock waste disposal in the region. The HNO 3 concentration at the monitoring site was lower than that reported in Seoul, 27 Quzhou, Beijing, 41 and New Delhi 42 but higher than that reported in Jeonju, 8 Seolseongmyeon, 27 Gucheng, 43 Niangon Adjamé 44 and San Diego 45 (Table 1).…”

Contributions of Ammonia to High Concentrations of PM2.5 in an Urban Area

“…NH3 is considered to be neutralized by sulfuric acid to form (NH4)2SO4, and then the excess NH3 reacts with other gaseous acidic species (i.e., HNO3 and HCl) to form NH4NO3 and NH4Cl [69]. Sung et al [18] measured NH3, NO3 − , and HNO3 at the same urban site from 2009 to 2018 (average NH3: ~7.8 μg/m 3 , NO3 − : ~3.0 μg/m 3 , and HNO3: ~1.7 μg/m 3 ) and reported that the urban area was under NH3-rich conditions based on the calculation of adjusted gas ratio of ~4, AdjGR = ( [70]. This indicates that, in the urban site, NH3 could be enough to form (NH4)2SO4, and then the excess NH3 could react with other gaseous acidic species to form NH4NO3 and NH4Cl.…”

“…Field measurements have shown that concentrations of atmospheric NH 3 generally vary depending on the season and location [9,[18][19][20][21][22][23][24][25][26][27]. NH 3 concentrations are temperaturedependent; they increase in summer and decrease in winter [9,20].…”