Use of biomarkers indices in a sediment core to evaluate potential pollution sources in a subtropical reservoir in Brazil

Abstract

The presence of PAHs, n-alkanes, pristane, and phytanes in core sediment from the Vossoroca reservoir (Parana, southern Brazil) was investigated. The total concentration of the 16 PAHs varied from 15.5 to 1646μgkg−1. Naphthalene was present in all layers (3.34–74.0μgkg−1). The most abundant and dominant n-alkanes were n-C15 and n-C36, with average concentrations of 198.1±46.8 and 522.9±167.7μgkg−1, respectively. Lighter n-alkanes were distributed more evenly through the layers and showed less variation, specially n-C9, n-C12, and n-C18, with average concentrations of 14.6±3.0, 31.6±1.9, and 95.0±5.2μgkg−1, respectively; heavier n-alkanes were more unevenly distributed.The study of the biomarker ratios indicates a slight influence from the nearby Highway BR 376: deposit of sediments coming from the pavement and sources of pyrolytic origin from the heavy traffic of vehicles and a gas station close to the sample point. In addition to this, the n-alkanes ratio analysis indicates that the region receives significant contribution from higher plants, with low contribution from autochthonous organic matter origin. Identified PAHs suggest pyrogenic sources formed during the pyrolysis of fossil fuels and direct influence from the heavy traffic from the nearby highway. The DBahA was found to be related to the contribution of particulate pavement, but only in significant concentrations after 15cm depth. Sediment fractions seem to be oxic, and the absence of phytane can be explained by several periods of bioturbation and tidal. In general, when compared with other studied sediments, the area seems low-polluted.