TY - JOUR
T1 - Nitrogen and sulfur compounds in ambient air and in wet atmospheric deposition at Mexico City Metropolitan Zone
AU - Rodolfo Sosa, E.
AU - Ana Luisa Alarcón, J.
AU - María Del Carmen Torres, B.
AU - Pablo Sánchez, A.
AU - Elías Granados, H.
AU - Mónica Jaimes, P.
AU - Armando Retama, H.
AU - Gay, David
AU - Lehmann, Christopher
N1 - Publisher Copyright:
© 2018 Air and Waste Management Association. All rights reserved.
PY - 2018
Y1 - 2018
N2 - Particulates and sulfur dioxide (SO2) were identified as the main atmospheric pollutants three decades ago in the Mexico City Metropolitan Zone (MCMZ). In order to reduce emissions of these pollutants, replacing fuel oil with natural gas, given this is one of the most important industries located inside MCMZ. This replacement strategy resulted in the reduction in the ambient air levels of both pollutants. SO2 no longer exceeds its ambient air quality standard; however acid rain remains a significant issue, being sulfate the principal component in the wet atmospheric deposition. In this study, spatial and temporal variations in the chemical composition of rain in Mexico City between 2003 and 2016 were analyzed; sulfate and nitrate ions and pH were obtained weekly at 16 sampling stations located in the MCMZ. Furthermore, sulfur dioxide (SO2) and nitrogen oxides (NOx) were evaluated from 1990 to 2016 at the MCMZ air quality monitoring network. SO2 levels have decreased from 1990 to 2016 by about 90%, while those of NOx by 20%. The SO2 / NOx ratio has declined about 60% indicating more effective strategies in reducing SO2 than for NOx emissions. The NOx emission sources are more diverse than for sulfur, and NOx has more complex mechanisms of atmospheric deposition and photochemistry. In 2003 a difference among the sampling sites was observed in the SO42- to NO3- equivalents ratio; sites located in the north presented a higher ratio of 2, while the sites located in the south the value was 1. In 2014, a homogeneous distribution was observed, where the ratio was the same in all the Mexico City sampling sites: 1.5 (µeq/L SO42- to µeq/L NO3-). The pH values of the samples at the stations located in the south were more acidic than the samples for the stations in the north. This result is in line with meteorological conditions, prevailing winds blowing from the north to the south, as well as emission sources located in the north sector, both inside as outside MCMZ.
AB - Particulates and sulfur dioxide (SO2) were identified as the main atmospheric pollutants three decades ago in the Mexico City Metropolitan Zone (MCMZ). In order to reduce emissions of these pollutants, replacing fuel oil with natural gas, given this is one of the most important industries located inside MCMZ. This replacement strategy resulted in the reduction in the ambient air levels of both pollutants. SO2 no longer exceeds its ambient air quality standard; however acid rain remains a significant issue, being sulfate the principal component in the wet atmospheric deposition. In this study, spatial and temporal variations in the chemical composition of rain in Mexico City between 2003 and 2016 were analyzed; sulfate and nitrate ions and pH were obtained weekly at 16 sampling stations located in the MCMZ. Furthermore, sulfur dioxide (SO2) and nitrogen oxides (NOx) were evaluated from 1990 to 2016 at the MCMZ air quality monitoring network. SO2 levels have decreased from 1990 to 2016 by about 90%, while those of NOx by 20%. The SO2 / NOx ratio has declined about 60% indicating more effective strategies in reducing SO2 than for NOx emissions. The NOx emission sources are more diverse than for sulfur, and NOx has more complex mechanisms of atmospheric deposition and photochemistry. In 2003 a difference among the sampling sites was observed in the SO42- to NO3- equivalents ratio; sites located in the north presented a higher ratio of 2, while the sites located in the south the value was 1. In 2014, a homogeneous distribution was observed, where the ratio was the same in all the Mexico City sampling sites: 1.5 (µeq/L SO42- to µeq/L NO3-). The pH values of the samples at the stations located in the south were more acidic than the samples for the stations in the north. This result is in line with meteorological conditions, prevailing winds blowing from the north to the south, as well as emission sources located in the north sector, both inside as outside MCMZ.
KW - Air quality
KW - Mexico City
KW - Nitrogen and sulfur compounds
KW - Wet atmospheric deposition
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M3 - Conference article
AN - SCOPUS:85056337219
SN - 1052-6102
VL - 2018-June
JO - Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA
JF - Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA
T2 - Air and Waste Management Association's 111th Annual Conference and Exhibition - Charting the Future: Environment, Energy and Health
Y2 - 25 June 2018 through 28 June 2018
ER -