Atmospheric concentrations of sulfur dioxide, nitrogen oxides, ammonia, hydrogen chloride, nitric acid, formic and acetic acids in the south of Vietnam measured by the passive sampling method

Characteristics of ammonia gas and fine particulate ammonium from two distinct urban areas: Osaka, Japan, and Ho Chi Minh City, Vietnam

Continuous and simultaneous measurements of ammonia gas (NH₃) and fine particulate ammonium (PM_2.5NH₄⁺) were performed in two distinct urban areas: Osaka, Japan, and Ho Chi Minh City (HCMC), Vietnam. Measurements were performed using a new online instrument. Two measurement periods were conducted during February 11-March 12, 2015 (cold period), and July 1-September 14, 2015 (warm period), at the urban site in Osaka, while 17 days of measurements, from May 21 to June 8, 2015, were conducted at the urban site in HCMC. The average NH₃ concentration at the HCMC site was much higher than that at the Osaka site. The differences in the NH₃ levels between the two cities are a result of their different emission sources. Traffic emission is a significant contributor to the NH₃ levels within the urban area in Osaka. Conversely, the contribution of traffic emission to the NH₃ levels in the HCMC urban area is negligible. With a population of around 8.5 million people living in the urban area of HCMC, the high NH₃ level is due to human sources and poor waste management systems, especially because of the high temperature (30 °C) and dense population of the city (density up to 42,000 inhabitants per km²). In contrast to the NH₃ levels, the highest PM_2.5NH₄⁺ level occurred during the cold period at the Osaka site, and the average level at this site was higher than that at the HCMC site. The availability of atmospheric acids, low temperature, and high humidity facilitates the formation of ammonium. Our results indicate that NH₃ plays a key role in secondary inorganic aerosol formation; therefore, it contributes to a significant amount of PM_2.5 at the Osaka site. In contrast, the high levels of PM_2.5 observed at the HCMC site are likely from road traffic emission, mainly motorcycles, rather than secondary inorganic aerosol formation.

Corrosion behavior of 316L and 304 stainless steels exposed to industrial-marine-urban environment: field study

The present investigation extensively compares the pitting corrosion behavior and mechanical stability of 316L and 304 stainless steels (SS) exposed to an Industrial-Marine-Urban (IMU) environment for 3 years from April 2012–March 2015.

RETRACTED: Development of new sensitive diffusive passive samplers for ambient air ozone and ozone concentration in HoChiMinh City

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Seasonal change in the atmospheric concentration of particulate polycyclic aromatic hydrocarbons in Ho Chi Minh City, Vietnam

We analyzed atmospheric particulate polycyclic aromatic hydrocarbons (PAHs) in Ho Chi Minh City, Vietnam, for 19 months. The average concentrations of total PAHs at dry and rainy seasons were 4.28 +/- 2.83 and 15.71 +/- 8.21 ng m(-3), respectively. The use of motorcycles without catalytic converters, estimated to be main emission sources of PAHs, would be higher during the dry season. PAH concentrations show a negative correlation with sunshine duration (r = -0.51). Furthermore, the ratio of average PAH concentration in the dry season to that in the rainy season shows a positive correlation with photolytic half-life (r = 0.94). Thus, seasonal changes in PAH concentrations are attributable to their photolytic degradation.

Determination of nitrogen dioxide, sulfur dioxide, ozone, and ammonia in ambient air using the passive sampling method associated with ion chromatographic and potentiometric analyses

Concentrations of nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), ozone (O(3)), and ammonia (NH(3)) were determined in the ambient air of Al-Ain city over a year using the passive sampling method associated with ion chromatographic and potentiometric detections. IVL samplers were used for collecting nitrogen and sulfur dioxides whereas Ogawa samplers were used for collecting ozone and ammonia. Five sites representing the industrial, traffic, commercial, residential, and background regions of the city were monitored in the course of this investigation. Year average concentrations of Collapse

Key Words

• nitrogen dioxide
• sulfur dioxide
• ozone
• ammonia
• determination
• ambient air
• ion chromatography
• potentiometry
• ion selective electrode

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Affiliation(s)

Alaa A. Salem Department of Chemistry, College of Science, United Arab Emirates University, Al-Ain, P.O. Box 17551, UAE
Ahmed A. Soliman Department of Chemistry, College of Science, United Arab Emirates University, Al-Ain, P.O. Box 17551, UAE
Ismail A. El-Haty Department of Chemistry, College of Science, United Arab Emirates University, Al-Ain, P.O. Box 17551, UAE

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Concentrations of atmospheric polycyclic aromatic hydrocarbons in particulate matter and the gaseous phase at roadside sites in Hanoi, Vietnam

We analyzed the concentrations of polycyclic aromatic hydrocarbons (PAHs) in both particulate matter (PM) and the gaseous phase at 10 roadside sites in Hanoi, Vietnam. The average concentrations of 47 PAHs ( summation 47PAHs) were 63 +/- 82 ng m(-3) in PM and 480 +/- 300 ng m(-3) in the gaseous phase. The PAHs mainly originated from motorcycles without catalytic converters. The highest concentrations of summation 47PAHs in both PM and the gaseous phase were observed at a terminal for buses and trucks. The operation of large commercial vehicles led to increased PAH pollution at the terminal site.