Supporting Information For s2

Supporting Information for:

Characteristics of Ammonia Gas and Fine Particulate Ammonium from Two Distinct Urban Areas: Osaka, Japan and Ho Chi Minh City, Vietnam

Duong Huu Huya,b*, Le Tu Thanhb, To Thi Hienb, Kazushi Noroa and Norimichi Takenakaa a Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1–1 Gakuen–cho, Naka–ku, Sakai–shi, Osaka 599–8531,

Japan b Faculty of Environmental Science, University of Science, Vietnam National University–Ho Chi Minh City, 227 Nguyen Van Cu Street, District 5, Ho Chi Minh

City, Vietnam

*Corresponding author: Tel.: (+81) (0) 72 254 9322, email: [email protected] + Table S1 Review of the gaseous NH3 and particulate NH4 in PM2.5 concentrations measurements in the urban atmosphere in Japan, Vietnam and other countries

+ No Locations Period Season NH3 (ppb) PM2.5 NH4 Method References . (µg m-3) 1 Ho Chi Minh, May 21 – Jun 8, 2015 0.74±0.30 NHx on-line This study Vietnam analyzer 2 Osaka, Japan Feb 11 – Mar 12, 2015 Winter 1.98±0.93 1.45±1.18 Jul 1 – Sep 14, 2015 Summer 4.21±2.30 0.93±0.61 3 Ho Chi Minh, 2002 Whole 19ᵃ Not measure Passive (Lan et al., 2004) Vietnam 4 Osaka, Japan 2005 Winter (Feb-Mar) 1.7 Not measure Passive (Nishikawa and Summer (Jul-Aug- 3.2 Kannari, 2011) Sep) 5 Yokohama, Japan 1987 – 1991 Winter 3.2 ± 1.8 2.3 – 3.4 Bubblers/Teflon filter (Yamamoto et al., Summer 11.3 ± 4.0 <2.3 1995) 6 Seoul, Korea Sep, 2010 – Aug, 2011 Winter 8.79 ± 3.55 Not measure WS-CRDSᵇ (Phan et al., in GJ site Summer 13.8 ± 4.52 2013) Seoul, Korea Winter 9.27 ± 3.39 in GS site Summer 14.2 ± 2.37 7 Kanpur, India 2007 – 2008 Winter 23.4 ± 7.2ᶜ 10.3 ± 2.8 NOx-NH3 (Behera and Summer 25.9 ± 5.6ᶜ 9.4 ± 1.7 analyzer/Teflon filterᵈ Sharma, 2010) 8 Shanghai, China 2013 – 2014 Winter 5.0 ± 3.2 Not measure DOASᵉ (Wang et al., Summer 9.1 ± 4.7 2015) 9 Barcelona, Spain May 6 – Sep 7, 2011 Summer 2.9 ± 1.3 Not measure AiRRmonia instrument (Pandolfi et al., (Background) 2012) May 13 – Jun 28, 2011 Summer 7.5 ± 2.8 (Traffic) 10 Manchester, UK 2004 – 2005 Winter 2.4 Not measure QCLASᶠ (Whitehead et al., Summer 3.0 2007) 11 Rome, Italy 2001 – 2002 (Traffic) Winter 25.3 ± 3.9ᶜ Not measure Annular Denuder (Perrino et al., Summer 24.1 ± 4.2ᶜ 2002) 2001 – 2002 Winter 4.8 ± 0.4ᶜ (Background) Summer 5.7 ± 1.4ᶜ 12 Atlanta, GA, US 2004 1.78 ± 1.11 Denuder/Teflon (Edgerton et al., 2007) North Birmingham, 1.58 ± 1.03 filter AL, US Gulfport, MS, US 1.10 ± 0.93 Pensacola, FL, US 1.07 ± 0.72 13 Atlanta, GA, US Jul – Dec, 2007 1.71 (Saylor et al., 2010) 14 Houston, TX, US Feb 12 – Mar 1, 2010 Winter 2.42 ± 1.16 Not measure EC-QCL- based sensorᶢ (Gong et al., Aug 5 – Sep 25, 2010 Summer 3.07 ± 2.87 2011)

Notes: ᵃ Estimation from the reported result; ᵇ WS-CRDS, Wavelength Scanned-Cavity Ring Down Spectroscopy; ᶜ Calculation from original data with unit of

-3 + µg m ; ᵈ NH3 measured by NOx-NH3 analyzer and NH4 in PM2.5 collected on Teflon filter and analyzed by ion chromatography; ᵉ DOAS, Differential optical absorption spectroscopy; ᶠ QCLAS, Aerodyne quantum cascade laser absorption spectrometer; ᶢ EC-QCL, External cavity quantum cascade laser-based sensor. Table S2 Summary of several NO plumes measured at the Osaka urban area during February and March 2015

Plumes ∆NH3/∆NO (mol/mol) Regression fits Correlation coefficients (R2) 12/2 0.30 Y = 0.22 X + 0.99 0.64 14/2 0.86 Y = 0.61 X + 0.75 0.52 15/2 0.55 Y = 0.53 X + 1.41 0.46 16/2-1 0.077 Y = 0.07 X + 0.58 0.87 16/2-2 0.78 Y = 0.96 X – 0.55 0.89 24/2 0.057 Y = 0.038 X + 2.2 0.65 25/2-1 0.36 Y = 0.25 X + 2.5 0.45 25/2-2 0.24 Y = 0.22 X + 1.5 0.92 26/2 0.1 Y = 0.12 X + 2.7 0.55 Average 0.37 ± 0.30 Fig. S1 Sampling locations in Osaka, Japan (left) and Ho Chi Minh City, Vietnam (right). Sampling points + Fig. S2 Time series concentrations of NH3 gas (top panel) and PM2.5NH4 (bottom panel) measured at the urban Osaka site over the periods February and March 2015 (green line) and July, August and September 2015 (red line) + Fig. S3 Time series concentrations of NH3 gas (top panel) and PM2.5NH4 (bottom panel) measured at the urban HCMC site over the period 21 May – 8 June 2015

+ Fig. S4 Correlation between PM2.5NH4 and PM2.5 mass concentrations measured at the urban Osaka site (left panel), and at the urban HCMC site (right panel)

Fig. S5 Diurnal variations of SO2, NO, traffic intensity, relative humidity (RH), temperature (Temp.), Ozone, Solar radiation (SR), wind speed (WS) and Planetary boundary layer height (PBL) measured at the urban Osaka site over the periods February and March 2015 (left panels) and July, August and September 2015 (right panels). Solid symbols represent the average concentrations. Top and bottom whiskers show one standard deviation (± SD) calculated from the average concentrations. Note that the planetary boundary layer heights with 3h resolution were achieved from the United State National Oceanic and Atmospheric Administration (NOAA) Real-time Environmental Application and Display System (READY) Fig. S6 Diurnal variations of NOx, Solar radiation (SR), O3, Planetary boundary layer height (PBL), Wind speed (WS), Relative humidity (RH) and Temperature measured at the urban HCMC site over the period 21 May – 8 June 2015. Solid symbols represent the average concentrations. Top and bottom whiskers show one standard deviation (± SD) calculated from the average concentrations. Note that the planetary boundary layer heights with 3h resolution were achieved from the United State National Oceanic and Atmospheric Administration (NOAA) Real-time Environmental Application and Display System (READY)

Fig. S7 Impacts of temperature and relative humidity on the ammonium particle fractions measured at the urban Osaka site (a) and at the urban HCMC site (b)

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