Vertical distribution of atmospheric trace metals and their sources at Mumbai,India

In the modern times, due to high rise multistoried buildings, especially in metropolitan cities, the habitable heights have changed from the ground floor level to higher levels. Present study is focused at generating a vertical profile of aerosols and the elemental concentrations in an un-inhabited environment in the envelope of a high rise building in a relatively clean environment of Mumbai. This can serve as a base line information to study the vertical profile in polluted areas like city centres and street canyons. Suspended particulate matter (SPM) at different floors and particle size distribution of aerosols at 12th floor (top floor) have been estimated. Thirteen trace metals, namely Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb and Zn were estimated in the SPM and in size separated aerosols, monitored over a period of 2 months. An attempt is also made to identify the sources of SPM at different heights using correlation matrix and factor analysis. The study indicates insignificant differences in the concentration levels of SPM and trace metals at different heights, when compared to the first floor level in the height range of 4.5–37.5 m. Of the 13 measured elements at the first floor level, Na (64.4%) and Ca (13.9%) constituted the dominant fractions followed by Fe (8.3%), Mg (5.7%), K (3.1%), Al (2.3%), Zn (1.3%) and Pb (0.5%). A similar distribution was also found for the 12th floor level (top floor). Factor analysis carried out using the measured elements, identified soil and sea salt spray as the main sources for the SPM at all the floors monitored.