Heavy metal contribution by runoff in a high-altitude megacity: a method based on the road-deposited sediment characterization

The objective of this paper is to present the development and application of a method to estimate the heavy metal (HM) contribution derived from the wash-off by runoff on road-deposited sediments (RDS) in a high-altitude megacity (Bogota, Colombia). The method is based on the development of a HM wash-off equation which considers two processes: HM transportation and HM leaching. HM contribution by runoff ranges between 24.7% and 50.3%, relative to the total mass per unit area of HMs associated with dry-weather RDS (Mn, Cd, As, Zn, Cu, Ba, Pb, and Fe). The HMs that show a greater contribution are Cd, Zn, and Mn. RDS size fraction below 250 μm contributes on average 81.6% of the total HM load washed-off by runoff. The findings suggest that the RDS size fraction below 250 μm must be the reference fraction for the control systems design of HM pollution in Bogota city.