The use of biomonitors and PIXE analysis in the study of air pollution in Mexico City

• Published in: X-ray spectrometry 2008-03, Vol.37 (2), p.156-162
• Main Authors: Cervantes, L., Ávila, O., Ruvalcaba, J. L., Miranda, J., Muñoz, R.
• Format: Article
• Language: English
• Subjects: Analysis methods; Analytical chemistry; Applied sciences; Atmospheric pollution; Bromeliaceae; Chemistry; Exact sciences and technology; Global environmental pollution; Pollution; Spectrometric and optical methods
• ISSN: 0049-8246; 1097-4539
• DOI: 10.1002/xrs.1056

An environmental study of air contamination in the Valley of Mexico is under investigation based on the use of two biomonitors: the epiphytic lichen Flavopunctelia flaventior (L.) Nyl, and bromeliaceae Thillandsia recurvata (Ruiz and Pav), which are rather sensitive to air pollution and have a great capability to absorb and accumulate airborne mineral elements, including heavy metals. The thalli of lichen samples were collected in a controlled area, La Marquesa National Park, while bromeliaceae were collected in San Juan Teacalco, Estado de México. Samples were subsequently transplanted to 13 sites corresponding to 12 stations of the automatic network of atmospheric monitoring in the metropolitan area of the Valley of Mexico and a control site. This region includes urban and industrial places and one rural station. The study area is located at an altitude of 2240 m, with about 20 million inhabitants; it includes 3.5 million vehicles and 35 000 industries as well. The samples of transplanted lichen and bromeliaceae were exposed during 6 months in different seasonal periods during the year from 2002 to 2003. Pellets were prepared from ashes of the exposed lichens and bromeliaceae. The contents of Cr, Cu, Fe, Ni, Mn, Pb, Zn, and other trace elements were determined by particle‐induced x‐ray emission (PIXE), using an external proton beam setup. Copyright © 2008 John Wiley & Sons, Ltd.