Abstract

Taltal is a commune located in Northern Chile, where former activities in copper ores processing left large amounts of mining waste enriched with potentially toxic elements, PTE. A soil pollution assessment using geochemistry and spatial distribution maps was conducted. A total of 101 surrounding soil samples from 3 abandoned mining waste sites (S1, S2, and S3) were taken to determine their content of PTE (Cu, Mo, Sb, Hg, Pb, Ni, Co, As, Mn, Cr, Cd, and Zn) and major elements. As guideline values of PTE in soils have not been established, the soil pollution index (PI) was assessed by comparing the soil PTE concentrations with the regional geochemical baseline (GBL) values and, for the first time, health risk for residents near Taltal city was evaluated. The measured PTE concentrations (mg kg(-1)) were Cu 18-6740, Mo 0.2-44, Sb 0.2-90, Hg 0.005-47, Pb 2.8-1510, Ni 7.0-138, Co 1.1-77.1, As 4.2-2691, Mn 83.4-11,400, Cr 7.7-46.1, Cd 0.05-23, and Zn 14.1-1394. Spatial distributions maps showed greatly polluted zones and under special concern are the concentrations of As, Co, Cu, Mo, Ni, Pb, Sb, Hg, Cd and Zn, which exceeded the GBL, the world-soil average and the USEPA and Finnish soil guidelines. Arsenic in site S2 and Cu and Pb in site S3 are the key factor that influences the potential ecological risk. Moreover, As in sites S1 and S2, and As, Pb and Cu in site S3 may pose non-carcinogenic effects for adults and children. Total cancer risk values were above the acceptable risk limit due to As, Cr, and Cd in sites S1 and S2, and due to As, Cr, Cd and Pb in site S3. Site S3, the largest abandoned site, represents the main environmental concern because of its high volume of waste and content of PTE. Based on the results, it can be suggested that the abandoned mining waste were dispersed and are the source of soil pollution in Taltal city. It is concluded that the abandoned mining waste sites have led to substantial contamination of the surrounding soils with As, Cu, Pb, Cr and Cd, which exceed ecological and/or human health risk guideline concentrations.