Polycyclic Aromatic Hydrocarbons in Road-Deposited Sediments and Roadside Soil in Tijuana, Mexico

Road-deposited sediment and roadside soil in the urban area of the city of Tijuana were collected and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs). The sigma PAH concentration for road-deposited sediment (RDS) ranged between 460 and 2027 mu g/kg with an average of 933 mu g/kg. The sigma PAH concentration in roadside soil was lower than in RDS, with a range between 54 and 1863 mu g/kg and a mean value of 308 mu g/kg. The diagnostic ratios showed that the PAHs originated mostly from pyrogenic sources such as gasoline and diesel combustion. The results show that PAH concentration in RDS and roadside soils is low when compared with other published studies. The low PAH levels found in this study are possibly related to differences in climate, urban features, and anthropogenic activities conducted in the studied areas. The toxicity equivalent concentrations (TEQ) of PAH calculated were also low in comparison with other studies. This is probably due to the lower concentration of total PAHs and the highly toxic high-molecular-weight PAHs.