Aliphatic and polycyclic aromatic hydrocarbons in surface sediments collected from mangroves with different levels of urbanization in southern Brazil

摘要

Three mangroves located in southern Brazil, Carijos (CA), Rio Tavares (RT) and Itacorubi (ITA), with distinct anthropogenic influences, were assessed with regard to the presence of aliphatic and polycyclic aromatic hydrocarbons (PAH). In this study, the n-alkane concentrations ranged from 1.9 mu g g(-1) (CA) to 55.6 mu g g(-1) (ITA) (dry weight). The carbon preference index (CPI) ranged from 2.1 to 7.9 and values for the terrestrial/aquatic ratio (TAR) were > 1. Thus, both indexes indicated the predominance of sediment of terrestrial origin, mainly comprised of higher plants. Concentrations of total PAH ranged from 6.8 ng g(-1) (RT) to 437.3 ng g(-1) (ITA). The PAH isomeric ratios indicated that these compounds originated mainly from pyrogenic sources. Nevertheless, levels of n-alkanes in the three mangroves were relatively low and they are considered typical of uncontaminated surface sediments, while the level of contamination with PAH was classified as low to moderate.