Atmospheric elemental concentration determined by Particle-Induced X-ray Emission at Tlaxcoapan in central Mexico, and its relation to Tula industrial-corridor emissions

The Tula-Vito-Apasco industrial corridor is considered one of the most contaminated zones in Mexico. In this corridor, at Hidalgo state, is located the Miguel Hidalgo refinery, the biggest in the country. Although ecology agencies monitor criterion contaminants in a routine basis, scarce data are available about elemental composition of particulate matter (PM). The PM10 elemental composition of Tula vicinity is being analyzed and results of the field study performed in Tlaxcoapan, Hidalgo are presented here. This small agricultural town is located within a 7.5 km from Tula-Vito-Apasco industrial corridor. PM10 fraction of atmospheric aerosols collected in filters from July to December 2007, was analyzed using Particle Induced X-ray Emission (PIXE) technique, and sixteen elements were detected. Temporal variations were observed during the studied period. Enrichment Factors were moderately high for S, Ca, V, Ni, Cu, Zn and Pb. Rain did not have strong influence but high amounts of sulfur were correlated to high amounts of Ni and V. Comparison of our results with other data from nearby allocations, shows good general agreement. A receptor model with principal component factor analysis (PCFA) and VARIMAX rotation was applied to data in order to estimate source apportionment. Four main sources were identified: soil that contributes to the elemental composition of filters with 26%, refinery and the power plant with 20% and two independent industrial emissions summed 26%. The last three polluting sources indicate that the industrial activities carried out in the corridor have a harmful impact in Tlaxcoapan, Hidalgo.