Forensic assessment of polycyclic aromatic hydrocarbons to reconstruct anthropogenic activities in a nearby urban reservoir

Abstract

This work examined the presence of polycyclic aromatic hydrocarbons (PAHs) in two sediment cores from the Passauna reservoir, in southern Brazil. The sediment cores contain organic matter deposited in the period comprising approximately 136 years for core I and 97 years for the core II. The distribution of PAHs reconstructs the historical atmospheric deposition for the city of Curitiba and therefore implies the anthropic activities in that period. Total concentrations of PAHs varied from 5.13 ng g−1 to 444.60 ng g−1 (core I) and 124.55 ng g−1 to 3018.14 ng g−1 (core II). The concentrations peaked in 1944 and 1958, reflecting the boom in the local economy. We identified the sources of PAHs by applying positive matrix factorization (PMF) and diagnostics ratios among PAHs compounds. According to PMF in core I 45.58% of PAHs are from diesel combustion, 32.19% from coal combustion and biomass burning, and 14.54% from vehicle emissions. In core II, vehicle emission contributed 40.91%, while 28.70% corresponds to traffic and biomass or coal combustion, 20.86% from petroleum sources, and 9.53% originated from biomass burning. The toxic level of sediments was determined considering the toxicity of PAHs equivalent to benzo(a)pyrene (TEQ) showed low carcinogenic risk, and considering the total concentration for core I (1.70–47.70 ng g−1) was lower than that of core II (11.64 ng g−1 to 899 ng g−1).