Chemical characteristics of aerosols and trace gas distribution over North and Central India

A field campaign on aerosol chemical properties and trace gases measurements was carried out along the Delhi–Hyderabad–Delhi road corridor (spanning about 3,200 km) in India, during February 1–29, 2004. Aerosol particles were collected on quartz and cellulose filters using high volume (PM10) sampler at various locations along the route (i.e., urban, semi-urban, rural, and forest areas) and have been characterized for major cations (Na+, Ca2+, Mg2+, K+, and NH4+), anions (Cl−, NO3−, and SO42−), and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb). Simultaneously, we measured NO2 and SO2 gases. These species show large spatial and temporal variations. The ambient PM10 concentration has been observed to be the highest (55 ± 4 μg m−3) near semi-urban areas followed by forest areas (48 ± 2 μg m−3) and in rural areas (44 ± 22 μg m−3). The concentrations of NOx (NO2+NO) and SO2 ranged from 16 to 69 μg m−3 and 4 to 11 μg m−3, respectively. Among anions, NO3− and SO42− are the major constituents of PM10. The urban and semi-urban sites showed enhanced concentrations of Fe, Zn, Mn, Cd, and Pb. This study provide information about atmospheric concentrations of various species in the northern to central India, which may be important for policy makers to better understand the air quality of the region.