Identification of the nature and source of atmospheric aerosols near the Taj Mahal (India).

The chemical composition of aerosol samples collected at Agra near the Taj Mahal during April 1991-June 1992 was identified by wet chemical analysis. The average concentration of suspended particulate matter (SPM) was 368.5 µg m(-3), ranging between 83 and 1305 µg m(-3), depending upon the season. Elevated levels of Na, SO4, Mg, NO3 and Cl compared to levels reported worldwide were attributed to the suspension of soil particles, as well as industrial emissions. Geometric mean enrichment factors of elements indicated two groups; one having enrichment factors less than 7 which were comprised of Na, K, Ca, Mg, Fe, Al, Mn and Si (crustal) and the other having enrichment factors greater than 13 and which were comprised of Ni, Cu, Zn, Pb, and Cd (non-crustal). Principal component analysis revealed the association of the first principal component with soil-derived elements while the second, third and fourth principal components were associated with industrial processes, wood combustion and brick kilns respectively. The study indicates that near the Taj Mahal the dominance of natural sources may enhance the degree of deterioration of the marble surface if micro-climatological conditions favour its wetting.