Analysis of size-segregated winter season aerosol data from New Delhi, India

Özet

Size distributions of particulate matter and twelve constituent elements were measured at a high trafficsite in New Delhi, India during winter 2013. While PM was found to be trimodal, individual elementsshowed varying size distribution patterns. Three key types of size distributions were observed includingunimodal with peaks either in the coarse (Al, Si) or fine (Pb) modes, bimodal with peaks in the fine range(S) and multimodal with peaks in accumulation and coarse (Cu, Sb) modes. Elements such as Al, Si and Fewere found to be in predominantly in the coarse range while Cu, Zn, Pb and Sb were found to be in thefine size range. Two modes dominate the size distribution. One is coarse (ca. 3 mm) and contains mainlycrustal elements and hence arises from sources such as soil, road dust, construction dust and possiblecoal fly ash. The other, more intense mode is fine (ca. 0.6 mm) and appears to comprise sulphate andanthropogenic trace metals which have entered the droplet mode through hygroscopic particle growthin the very high humidity conditions of the Delhi winter. A third, less intensive mode ca. at 0.2 mmprobably arises from relatively fresh anthropogenic emissions which have not grown into the dropletmode.