Aerosols and trace gases characterization over Indo-Gangetic plain in semiarid region

• This study deals with characterization of aerosol and trace gases over Indo Gangetic plain.
• TSPM loads are much higher than recommended values set by National Ambient Air Quality in India.
• Trace gas concentrations are in the reported range.
• Fog has played important role in levels of aerosols and its chemical constituents.
• Meteorological conditions play important role in winter season.

This paper deals with measurements of aerosols, their chemical properties and precursor trace gases at Agra in the Indo-Gangetic plain. The average TSPM level is 441.2 μg m−3 and ranges between 60.8 μg m−3 and 1004.6 μg m−3 which are higher than National Ambient Air Quality Standard Values of India. High wind speed from North West direction influences the aerosol load. TSPM load is higher during prefoggy/foggy days and lower during post foggy days. NH4+ concentration is highest followed by NO3−, SO42−, Cl−, K+, Ca2+, Na+, Mg2+ and F−. The high concentration of NH4+ may be probably due to nearby cattle yard, use of fertilizers and biogenic emissions. The concentration of trace gases SO2, NO2, HNO3 and NH3 are 20.8 μg m−3, 26.3 μg m−3, 1.6 μg m−3, 18.6 μg m−3, respectively. The transportation of urban plumes may be responsible for high concentration of SO2 and NO2. HNO3/NO3− ratio is less than unity. There was no correlation between SO2 and SO42−. The ratio of SO42− + NO3− + Cl−/NH4+ are 1.8 and 2.3, respectively indicate that acidifying components are not neutralized only by NH4+ ion.