Abstract
The study reports day and nighttime temporal variation of prominent water-soluble inorganic species (WSIS) of fine and coarse mode particulate matter at a site in central Delhi for 2012 and 2013. The two years’ concentrations of major ionic species (NH4+, K+, Ca2+ and Mg2+ and NO3-, SO42-) showed that mean levels of both ∑cations and ∑anions were higher in nighttime than daytime in both PM2.5 and PM10. Moreover, the difference of mean levels in daytime and nighttime was noticed higher in PM2.5 compared to PM10. Among anions, more variation was observed for NO3-, i.e., ~49% higher level in nighttime compared to daytime, while~9% higher values in the nighttime for SO42-. Higher variation of NO3- level might be due to active participation of NOx in daytime photo-oxidation process. Among cations,Ca2+ and Mg2+ showed higher concentration in daytime compared to nighttime. Higher day and nighttime variation of Ca2+ and Mg2+ in coarse particulate matter suggested their dominance in PM10 compared to PM2.5. In PM10, the highest Ca2+ concentration was observed in daytime summer and least in nighttime monsoon, indicating the role of loose soil and meteorological conditions. The higher daytime SO42- concentration in monsoon compared to summer show edits significant formation as secondary aerosols in fine mode. The reactive nitrogen species NO3- and NH4+ were correlated during the day and nighttime in PM2.5 and PM10.Moreover, NH4+ was highly correlated to SO42- and NO3-, mainly in the form of (NH4)2SO4 and NH4NO3.
Highlights
The physicochemical properties of the atmosphere get affected by particulate matter by altering its composition and may alter ambient air quality, visibility, cloud formation, and consecutively energy entering, absorbed, reflected, and emitted by earth system.[1,2,3] it can affect human health adversely and may alter the ecosystem.[4,5,6] the chemical characterization of PM is necessary for the development of an air quality improvement programme to control the implications.[7,8] Delhi is considered a city where PM load is usually higher than the permissible limits, and its chemical description is needed at regular intervals of time
Higher day and nighttime variation of Ca2+ and Mg2+ in coarse particulate matter suggested their dominance in PM10 compared to PM2.5
The results showed that the mean levels of both ∑cations and ∑anions were higher in nighttime than daytime in PM2.5 and PM10
Summary
The physicochemical properties of the atmosphere get affected by particulate matter by altering its composition and may alter ambient air quality, visibility, cloud formation, and consecutively energy entering, absorbed, reflected, and emitted by earth system.[1,2,3] it can affect human health adversely and may alter the ecosystem.[4,5,6] the chemical characterization of PM is necessary for the development of an air quality improvement programme to control the implications.[7,8] Delhi is considered a city where PM load is usually higher than the permissible limits, and its chemical description is needed at regular intervals of time. The primary sources of pollutants impacting the air of Delhi are the burning of fossil and biomass fuels, rapid urbanization, industrialization, and transportation.[9,10,11] Due to the potential effect of water-soluble components on rain chemistry, human health, and air quality, water-soluble inorganic components are studied extensively.[12,13,14,15,16] Several anthropogenic activities such as agricultural, vehicular, industrial, and burning of biomass consecutively transform secondary inorganic particles such as sulphate and nitrate.[9,17,18,19]
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