Nonintrusive, Fast and Sensitive Ammonia Detection by Laser Photothermal Deflection

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Summer ammonia measurements in a densely populated Mediterranean city

Real-time measurements of ambient concentrations of gas-phase ammonia (NH 3) were performed in Barcelona (NE Spain) in summer between May and September 2011. Two measurement sites were selected: one in an urban background traffic-influenced area (UB) and the other in the historical city centre (CC). Levels of NH 3 were higher at CC (5.6±2.1 μgm ?3 or 7.5±2.8 ppbv) compared with UB (2.2±1.0 μgm?3 or 2.9±1.3 ppbv). This difference is attributed to the contribution from non-traffic sources such as waste containers, sewage systems, humans and open markets more dense in the densely populated historical city centre. Under high temperatures in summer these sources had the potential to increase the ambient levels of NH 3 well above the urban-background-traffic-influenced UB measurement station. Measurements were used to assess major local emissions, sinks and diurnal evolution of NH 3. The measured levels of NH 3, especially high in the old city, may contribute to the high mean annual concentrations of secondary sulfate and nitrate measured in Barcelona compared with other cities in Spain affected by high traffic intensity. Ancillary measurements, including PM10, PM2.5, PM1 levels (Particulate Matter with aerodynamic diameter smaller than 10 μm, 2.5 μm, and 1 μm), gases and black carbon concentrations and meteorological data, were performed during the measurement campaign. The analysis of specific periods (3 special cases) during the campaign revealed that road traffic was a significant source of NH 3. However, its effect was more evident at UB compared with CC where it was masked given the high levels of NH 3 from non-traffic sources measured in the old city. The relationship between SO2? 4 daily concentrations and gas-fraction ammonia (NH 3/(NH 3 +NH + 4 )) revealed that the gas-to-particle phase partitioning (volatilization or ammonium salts formation) also played an important role in the evolution of NH 3 concentration in summer in Barcelona. © 2012 Author(s). CC Attribution 3.0 License

Summer ammonia measurements in a densely populated Mediterranean city

Real-time measurements of ambient concentrations of gas-phase ammonia (NH 3) were performed in Barcelona (NE Spain) in summer between May and September 2011. Two measurement sites were selected: one in an urban background traffic-influenced area (UB) and the other in the historical city centre (CC). Levels of NH 3 were higher at CC (5.6±2.1 μgm ?3 or 7.5±2.8 ppbv) compared with UB (2.2±1.0 μgm?3 or 2.9±1.3 ppbv). This difference is attributed to the contribution from non-traffic sources such as waste containers, sewage systems, humans and open markets more dense in the densely populated historical city centre. Under high temperatures in summer these sources had the potential to increase the ambient levels of NH 3 well above the urban-background-traffic-influenced UB measurement station. Measurements were used to assess major local emissions, sinks and diurnal evolution of NH 3. The measured levels of NH 3, especially high in the old city, may contribute to the high mean annual concentrations of secondary sulfate and nitrate measured in Barcelona compared with other cities in Spain affected by high traffic intensity. Ancillary measurements, including PM10, PM2.5, PM1 levels (Particulate Matter with aerodynamic diameter smaller than 10 μm, 2.5 μm, and 1 μm), gases and black carbon concentrations and meteorological data, were performed during the measurement campaign. The analysis of specific periods (3 special cases) during the campaign revealed that road traffic was a significant source of NH 3. However, its effect was more evident at UB compared with CC where it was masked given the high levels of NH 3 from non-traffic sources measured in the old city. The relationship between SO2? 4 daily concentrations and gas-fraction ammonia (NH 3/(NH 3 +NH + 4 )) revealed that the gas-to-particle phase partitioning (volatilization or ammonium salts formation) also played an important role in the evolution of NH 3 concentration in summer in Barcelona. © 2012 Author(s). CC Attribution 3.0 License

Miniaturized measurement system for ammonia in air

The development of a miniaturized ammonia sensor made using microsystem technology is described. Gas is sampled in a sampler comprising two opposite channels separated by a gas permeable, water repellent polypropylene membrane. Subsequently, the acid sample solution is pumped into a selector where an alkaline solution is added to ionize all sampled ambient acid gasses, resulting in an enhanced selectivity. In the selector, the ammonia can diffuse through a second membrane into a purified water stream where an electrolyte conductivity sensor quantifies the resulting ammonium concentration. The realized system is shown to be selective enough not to be influenced by normal ambient carbon dioxide concentrations. Experiments with a gas flow of 3 ml/min, containing ammonia concentrations ranging from 9.8 to 0.3 ppm in a nitrogen carrier flow, into a 15 μl/min sample solution flow and finally into a 5 μl/min purified water stream have been carried out and show that the system is sensitive to ammonia concentration below 1 ppm. \u

Summer ammonia measurements in a densely populated Mediterranean city

Real-time measurements of ambient concentrations of gas-phase ammonia (NH3) were performed in Barcelona (NE Spain) in summer between May and September 2011. Two measurement sites were selected: one in an urban background traffic-influenced area (UB) and the other in the historical city centre (CC). Levels of NH3 were higher at CC (5.6±2.1 μgm?3 or 7.5±2.8 ppbv) compared with UB (2.2±1.0 μgm?3 or 2.9±1.3 ppbv). This difference is attributed to the contribution from non-traffic sources such as waste containers, sewage systems, humans and open markets more dense in the densely populated historical city centre. Under high temperatures in summer these sources had the potential to increase the ambient levels of NH3 well above the urban-background-traffic-influenced UB measurement station. Measurements were used to assess major local emissions, sinks and diurnal evolution of NH3. The measured levels of NH3, especially high in the old city, may contribute to the high mean annual concentrations of secondary sulfate and nitrate measured in Barcelona compared with other cities in Spain affected by high traffic intensity. Ancillary measurements, including PM10, PM2.5, PM1 levels (Particulate Matter with aerodynamic diameter smaller than 10 μm, 2.5 μm, and 1 μm), gases and black carbon concentrations and meteorological data, were performed during the measurement campaign. The analysis of specific periods (3 special cases) during the campaign revealed that road traffic was a significant source of NH3. However, its effect was more evident at UB compared with CC where it was masked given the high levels of NH3 from non-traffic sources measured in the old city. The relationship between SO2? 4 daily concentrations and gas-fraction ammonia (NH3/(NH3 +NH+4 )) revealed that the gas-to-particle phase partitioning (volatilization or ammonium salts formation) also played an important role in the evolution of NH3 concentration in summer in Barcelona. © 2012 Author(s). CC Attribution 3.0 License