Lichens as bio-monitors of polycyclic aromatic hydrocarbons: Measuring the impact of features and traffic patterns

Diana Marcela Uribe; Lina María Ortega; Marco Tadeu Grassi; Rafael Garrett Dolatto; Nazly Efredis Sánchez

doi:10.1016/j.heliyon.2023.e20087

Lichens as bio-monitors of polycyclic aromatic hydrocarbons: Measuring the impact of features and traffic patterns

Heliyon. 2023 Sep 13;9(9):e20087. doi: 10.1016/j.heliyon.2023.e20087. eCollection 2023 Sep.

Authors

Diana Marcela Uribe¹, Lina María Ortega¹, Marco Tadeu Grassi², Rafael Garrett Dolatto², Nazly Efredis Sánchez³

Affiliations

¹ Programa de Ingeniería Ambiental, Universidad del Cauca, carrera 2 #15N, Popayán, Cauca, Colombia.
² Department of Chemistry, Universidade Federal do Paraná, Jardim das Américas, Caixa Postal 19032, CEP 81531-980, Curitiba, Brazil.
³ Departamento de Ingeniería Ambiental y Sanitaria, Universidad del Cauca, Carrera 2 #15N, Popayán, Cauca, Colombia.

Abstract

The role of road characteristics, including gradient and speed control devices, in influencing emission dynamics remains to be fully elucidated. Most studies have focused on fuel consumption as an indirect indicator of sector emissions instead of directly quantifying specific pollutants, like polycyclic aromatic hydrocarbons (PAHs). This research approach is often due to the complexities involved in capturing these pollutants and their subsequent analysis. Bio-monitors, such as lichens, offer an economically viable method. Their wide distribution across various habitats enables the comparison of PAH levels in diverse environments. Against this background, The present work analyses the ability of tropical lichens to indicate the effect that traffic patterns and geometric design features of roads (traffic activity, road gradient, traffic control devices, and vehicular speed) have on the emission of PAH concentration. Results showed that PAHs in lichens strongly correlated with the road gradient (Spearman correlation, $p < 0.005$ with $R = 0.98$ ). Each 1% increase in road gradient implies a rise of 24 ng_PAH/g_Lichen in National Road. Additionally, a trend coherent of PAH concentration with the vehicle speed profile was observed on Panamericana Road. Speed control devices were associated with higher concentrations of PAHs due to acceleration and braking actions that increment fuel consumption. Finally, the results evidenced that lichens helped determine the source of aromatics and their carcinogenic potential using the diagnostic ratio of PAHs and the carcinogenic equivalence sum, respectively.

Keywords: Air pollution; Carcinogenic equivalence sum; Road gradient; Speed control devices.