Comparison of Polycyclic Aromatic Hydrocarbon (PAHs) concentrations in urban and natural forest soils in the Atlantic Forest (Sao Paulo State)

Studies about pollution by Polycyclic Aromatic Hydrocarbons (PAHs) in tropical soils and Brazil are scarce. A study was performed to examine the PAHs composition, concentrations and sources in red-yellow Oxisols of remnant Atlantic Forest of the Sao Paulo State. Sampling areas were located in an urban site (PEFI) and in a natural one (CUNHA). The granulometric composition, pH, organic matter content and mineralogical composition were determined in samples of superficial soils. The sum of PAHs (Sigma HPAs) was 4.5 times higher in the urban area than in the natural one. Acenaphthylene, acenaphthene, fluorene, phenanthrene and fluoranthene have been detected in the soils of both areas and presented similar concentrations. Acenaphthene and fluorene were the most abundant compounds. Pyrene was twice more abundant in the soils of natural area (15 mu g.kg(-1)) than of the urban area and fluoranthene was the dominant compound (203 mu g.kg(-1)) in urban area (6.8 times higher than in the natural area). Some compounds of higher molecular weight, which are tracers of vehicular emissions showed significant concentrations in urban soils. Pyrene represented 79% of Sigma PAHs whereas it has not been detected in natural soils. The results showed that forest soils in urban area are characterized by the accumulation of high molecular weight compounds of industrial and vehicular origin.