Elemental Composition of PM 2.5 in Araraquara City (Southeast Brazil) during Seasons with and without Sugar Cane Burning

Abstract

Particulate\rmatter with an aerodynamic diameter below 2.5 μm (PM2.5), present in\rpolluted air, has been associated with a large spectrum of health impairments,\rmainly because of its deep deposition into the lungs. Araraquara City (Southeast\rBrazil) is surrounded by sugar-cane plantations, which are burned to facilitate\rthe harvesting; this process causes environmental pollution due to the large\ramounts of soot that are released into the atmosphere. In this work, the\relemental composition of PM2.5 was studied in two scenarios, namely\rin sugar-cane harvesting (HV) and in non-harvesting (NHV) seasons. The sampling\rstrategy included one campaign in each season. PM2.5 was collected\rusing a dichotomous sampler (10 L·min-1, 24 h) with PTFE\rfilters. Information concerning the bulk elemental concentration was provided\rby energy-dispersive X-ray fluorescence. Enrichment factor analysis indicated\rthat S, Cl, K, Cr, Ni, Cu, Zn, As, Cd and Pb were highly enriched relative to\rtheir crustal ratios (to Al). Principal component analysis was used to get some\rinsight about the sources of the elements. Principal component 1 (PC1)\rexplained 30.5% of data variance. The elements that had high loading (>0.7)\rwere: S, Cr, As, and Pb; these are associated with combustion of fossil fuels.\rIn principal component 2 (PC2), Cl, Cu, Zn, and Cd showed high loadings; these\relements are associated with biomass burning. The Ni concentration found is\rthree times larger than the threshold of risk for lung cancer, as recommended\rby the World Health Organization.