Evaluación del contenido de metales pesados en sedimentos viales urbanos : adaptaciones internacionales en salud pública para Bogotá D.C. (Colombia)

Abstract

Road sediments (SV) are complex formations that have high concentrations of organic and inorganic pollutants such as heavy metals (MP), this compared to the background levels of surrounding areas. In road environments it has been possible to determine the relationship between vehicular traffic and the content of MP in SV, that is why worldwide, statistical methods have been used to identified the possible sources (e.g., brake pads, tires and wear of moving components), as well as methods for assessing the degree of accumulation of pollutants in soils; achieving a better understanding in terms of enrichment levels, toxicity potential and the risks associated with their exposure to the environment and public health. In the case of Bogotá, we used the relationship found worldwide and locally between the average daily traffic (TPD) and the dry season concentration of MP in the SV for the size fraction <250 μm, to predict the degree of pollution of six of the most reported MPs in the literature (i.e., Pb, Zn, Cu, Cd, Ni and Cr) and the possible sources, through principal component analysis (ACP). From these data and with the use of the geo-accumulation index (Igeo) and integrated pollution index (IPI), it was possible to identify the points of the city with the highest degrees of metallic enrichment and, also, through the ecological risk index (RI) it was determined the sectors where the biological community has the highest sensitivity. Through the carcinogenic (CR) and non-carcinogenic (HI) risk indices, a first approximation of the risk could be made on the child and adult community due to exposure to the MPs contained in the city's SV. As conclusions, it was possible to establish according to the background levels worldwide, that Ni and Cr are the MPs that presented the lowest enrichment. On the other hand, the Pb was the MP with highest Igeo and the one with the greatest contribution in the multi-element assessment evaluated through the IPI. Otherwise, an environmental risk between moderate and considerable was identified within the area of influence of the roads with the greatest TPD in the localities of Kennedy, Suba and Barrios Unidos. Likewise, it was determined that the non-carcinogenic risks for the children's community due to exposure to MP are greater than for the adult community, and are mainly associated with the ingestion of sediment particles, where the Pb and Cr, due to their high toxicity, are the MPs that most contribute in the integrated multi-element assessment; while the carcinogenic risk assessment showed no significant risk for developing cancer in adulthood. Finally, it is recommended to develop studies for the determination of the background values corresponding to the city of Bogotá, as well as the sampling of a greater number of points that better identify the heterogeneity of the land use characteristic of the different localities in the city; so that in this way the level of pollution and its impact on the environment and urban public health can be accurately identified.