Occurrence of Polycyclic Aromatic Hydrocarbons in the Waters from the Déganobo Lacustrine System, Côte d’Ivoire: Contamination Levels, Sources, Ecological and Health Risks

Abstract

This study aimed to assess the contamination levels of the waters in the Déganobo lake system by the sixteen polycyclic aromatic hydrocarbons (PAHs) designated as priority pollutants by the U.S. Environmental Protection Agency. Furthermore, it sought to determine their origins within these waters and evaluate the associated ecological and human health risks. To achieve this, 96 water samples were collected from the lake system over a one-year period, from August 2021 to July 2022, and subsequently analyzed in accordance with. The origin of PAHs in these waters was determined using molecular weight ratios of specific compounds. Contamination levels were assessed following the SEQ-Eau V2 guidelines. Ecological and human health risks were estimated using Directive 2013/39/EU, the hazard index, benzo[a]pyrene toxic equivalent quotients (TEQ-BaP), benzo[a]pyrene mutagenic equivalent quotients (MEQ-BaP), the incremental risk-related BaP dose (RI-BaP dose), and incremental lifetime cancerogenic risks. Phenanthrene was found to be the most abundant PAH in these waters, with an average concentration of (10.3±1.5) µg/L, while benzo(j)fluoranthene was the least abundant, at (0.02±0.01) µg/L. Low molecular weight PAHs (2 to 3 benzene rings) predominated, reaching (20.2±2.8) µg/L, whereas high molecular weight PAHs were less represented, at (2.1±0.1) µg/L. The origin of PAHs in these waters was primarily pyrolytic. The water quality was deemed poor, mainly due to the presence of benzo(b)fluoranthene ((1.7±0.3) µg/L) and indeno(1,2,3-c,d)pyrene ((0.5±0.1) µg/L). Overall, the associated health risks, particularly carcinogenic and mutagenic effects of these PAHs on the ecosystem's biota and human health, were found to be elevated.