Elemental analysis of soils as possible resuspended dust sources in Mexico city

Soil samples were collected from seven sites in and around the Metropolitan Area of Mexico City. The locations were chosen as possible sources of fugitive dusts which contribute to suspended particulate matter in the atmosphere of Mexico City. X-ray Fluorescence [XRF] was used to determine the concentrations of several major elements [Si, K, Ca, Ti, Mn, and Fe], as well as of other trace elements that might be useful to identify the source of the airborne particles [Cr, Ni, Cu, Zn, Rb, Sr, Y, and Zr], while X-ray Diffraction [XRD] was employed to identify the most important mineral phases present in the samples. It was found that the concentrations of some elements and the presence of minerals [like albite, quartz, and calcite] show a certain similarity to those determined by other authors in samples of Total Suspended Particles [TSP] from this urban area. Also, a comparison is made with ratios of published elemental compositions of fugitive dust profiles for inhalable particulate matter [PM[10] and PM[2.5]]. The ratio Mn/Fe obtained in this work is very similar to all other studies, suggesting a crustal origin, while the ratios Cr/Fe and Ni/Fe in the other studies may be affected by anthropogenic sources

Contribution of soil, sulfate, and biomass burning sources to the elemental composition of pm[10] from Mexico City

This study is aimed to identify sources of particulate matter with mean aerodynamic diameter below 10 microm [PM[10]] present in the atmosphere of the Metropolitan Area of Mexico City [MAMC], using samples obtained from January 1st to June 30th, 2009, analyzed with X-ray spectrometric techniques. MiniVol samplers were used to collect samples on polycarbonate filters in three sites [North, Center, and South] of the MAMC. The filters were exposed along 24 h every two days, starting at 8:00 AM, and then analyzed with particle induced X-ray emission [PIXE], a microPIXE [microPIXE] system, and X-ray fluorescence [XRF]. Statistical multivariate tests with positive matrix factorization [PMF] were conducted to identify possible contributing factors. The model HYSPLIT was used to determine back-trajectories and the MODIS database for fire spot localization. The multivariate methods identified five factors in the Center and South, and four in the North, including Soil, Sulfate, Fuel/Industry, and Biomass burning, with certain differences in the factors and contributions. Application of HYSPLIT back-trajectories associated these factors to three main Soil sources and points of secondary aerosols production, as well as locations where Biomass burning aerosols were originated. The combination of X-ray spectrometric methods, receptor modeling, back-trajectory determination, and fire site localization, allowed the identification of possible sources of PM[10] in the MAMC, namely, the dry Texcoco lake, the Toluca Valley, and the North dry plains for Soil aerosols, the influence of local industrial areas for Sulfate [secondary] aerosols, and the appearance of fires for Biomass burning