Polycyclic aromatic hydrocarbon (PAH) patterns in climatically different ecological zones of Brazil

Understanding the global distribution of PAHs requires knowledge of their sources. The objective of our work was to test the hypothesis that termites and woody plants are sources of naphthalene (NAPH), phenanthrene (PHEN), and perylene (PERY) for soils of different tropical climates. We determined the concentrations of 20 PAHs in soil, wood, and different compartments of termite nests (central part, inner wall, outer wall) in the Amazon (Terra firme, Várzea, and Igapó), Pantanal, Cerrado, Mata Atlântica, and Caatinga regions. The sum of 20 PAH concentrations was low in all soils (4.8–347 μg kg−1, n=47) and much higher in many of the wood (47–3894, n=31) and termite nest samples (29–4208, n=121). In general, NAPH, PHEN, or PERY were most abundant. In the Amazon region, wood samples contained up to 3785 and termite nest samples up to 3645 μg kg−1 of NAPH. In all regions, most termite nests contained higher PERY concentrations (up to 1109 μg kg−1) than wood or soil, indicating that PERY was produced or accumulated in these nests. In many termite nests, the central part had larger NAPH and PERY concentrations than the wall, indicating that these compounds may have been produced within the nests. With few exceptions, NAPH dominated the PAH pattern in the Amazon and west Cerrado regions, PHEN in the Mata Atlântica and Caatinga regions, and PERY in the Pantanal and central Cerrado regions. Our results suggest that there are large unknown sources of NAPH, PHEN, and PERY in the tropical environment. It is likely that part of these sources is biological. The release of NAPH and PHEN from these sources seems to depend on climatic factors.