Land-use-dependent spatial variation and exposure risk of heavy metals in road-deposited sediment in Villavicencio, Colombia.

Urbanization-induced land-use changes cause several environmental problems, especially in developing countries due to a lack of sufficient urban planning. This study was performed in a medium-size city of Villavicencio, Colombia. Copper, lead, nickel, zinc, chromium, manganese, and cadmium in road-deposited sediment (RDS) from different land uses were determined. Multiple geo- and statistical approaches of geographic information system mapping, Pearson correlation, Kruskal-Wallis H, hierarchical cluster analysis (HCA), and principal component analyze (PCA) were employed to assess the influence of land use on the metals' spatial distribution. The enrichment of given metals in RDS was evaluated by geo-accumulation (I) and pollution load (PLI) indexes. The exposure human health risk was assessed by hazard index (HI). Results show that the average contents of the given metals decreased in the order of commercial > residential > highway > government institutions and public parks areas. Commercial areas thereafter always have the highest metals enrichment (I) and pollution level (PLI). HI assessment indicates that child has a higher health risk than adult due to the exposure to metals in RDS. HCA analysis reveals that surface roughness had a more direct influence than land-use type on metals' distribution. Kruskal-Wallis H test further suggests land-use type had a significant influence on certain metals' spatial variation. Two potential (group) sources of geochemical and vehicular sources, along with leaded petrol and paintings, were inferred to be the main contributors to metals in RDS by PCA analysis.