Chemical characterization of atmospheric PM in Delhi, India, during different periods of the year including Diwali festival

Abstract

A study of the chemical composition of atmospheric particulate matter has been carried out in the city of Delhi. During two 6–day special observation periods, in November 2009 and in March 2010, we have determined atmospheric concentration of element, ions, elemental carbon, organic carbon and levoglucosan, obtaining a satisfactory mass closure (better than 94%). The results show that during these periods, pollutants produced by combustion sources constituted 6 –7 % of the total mass, and that the rest of it, in the absence of desert storms, was evenly divided among species coming from the soil, inorganic secondary compounds formed in the atmosphere and organic species. The results of the analysis of levoglucosan concentration showed that during the cold season in the atmosphere of Delhi about one fifth of the organics was directly produced by biomass burning.Elemental content of PM10 has also been determined once a week during the year 2008. It has been found that PM10 composition varies according to the season: soil components increase during the summer while secondary pollutants and organics increase during the post–monsoon and the winter.Elemental and ionic content of PM10 and PM2.5 have been determined every day during the week of Diwali festivals in 2008 and 2009. PM10 concentration has reached the value of 767μg m−3 in 2008 and 620μg m−3 in 2009; a remarkable increase of elements produced by firework combustion (Sr, Ba, Ti, Mg, Cu, K, S, V, Cl, Bi, Ga) has been detected. The analysis of the extractable and residual fraction of elements has shown that most of the elements were predominantly in the residual fraction and that changes in the size and solubility distribution occurred as a consequence of fireworks.