Spatial study of elemental carbon present in the respirable fraction of PM2.5 through rutherford backscattering spectrometry in the metropolitan area of the Toluca valley

Abstract

Carbon originates compounds that are characterized by having atoms linked to other elements in their structure, such as oxygen, hydrogen and nitrogen. Many of them are very useful for living beings; however, others such as monoxide and carbon dioxide are considered of high risk for the populations that inhale them, in addition to their impact on climate change. Therefore, monitoring carbon concentrations in the atmosphere is vital. This research aims to determine the presence and concentration of elemental carbon in suspended particles with aerodynamic diameter equal to or less than 2.5 µm by means of the backscattering technique of Rutherford. For this, 10 samples were collected at six sites in the Toluca Valley Metropolitan Area during the sampling campaign (November 2016-November 2017) and analyzed with the Van de Graaff tandem accelerator. A proton beam was used, with energy of 2.5 MeV, which collided elastically with the atoms in the sample (target), being dispersed at a certain angle and at an energy, characterizing the mass of the dispersing center. The particles thus dispersed were registered by a surface barrier detector, obtaining an energy spectrum. The spectrum analysis was done with the SIMNRA software.