Characterization of organic aerosol at a rural site influenced by olive waste biomass burning

Abstract

Biomass burning is a major air pollution problem all around the world. However, the identification and quantification of its contribution to ambient aerosol levels is a difficult task due to the generalized lack of observations of molecular markers. This paper presents the results of a yearlong study of organic constituents of the atmospheric aerosol at a rural site in southern Spain (Villanueva del Arzobispo, Ja en). Sampling was performed for PM10 and PM2.5, and a total of 116 and 115 samples, respectively, were collected and analyzed by GC/MS, quantifying 77 organic compounds. Higher levels of organic pollutants were recorded from November to March, coinciding with the cold season when domestic combustion is a common practice in rural areas. This jointly with adverse meteorological conditions, e.g. strong atmospheric stability, produced severe pollution episodes with high PMx ambient levels. High daily concentrations of tracers were reached, up to 26 ng m 3 for B(a)P and 6065 ng m 3 for levoglucosan in PM2.5, supporting that biomass burning is a major source of pollution at rural areas. A multivariate statistical study based on factor and cluster analysis, was applied to the data set with the aim to distinguish sources of organic compounds. The main resulting sources were related with biomass combustion, secondary organic aerosol (SOA), biogenic emissions, lubricating oil and soil organic components. A preliminary organic source profile for olive wastes burning was evaluated, based on cluster results, showing anhydrosacharides and xylitol are the main emitted compounds, accounting for more than 85% of the quantified compounds. Other source compounds were fatty acids, diacids, aliphatics, sugars, sugar alcohols, PAHs and quinones.