DETERMINATION OF MINING ACTIVITY OF RIVER SEDIMENTS OF THREE CHILEAN BASINS BY PARTICLE INDUCED X-RAY EMISSION (PIXE)

Mining is one of the most important industrial activities in Chile and there is growing concern on pollution by some mining and metallurgical processes. We have studied the contents of heavy metals in sediments from three river basins in Chile. Samples were collected based on hydrologic criteria in six sites along the rivers in their path from the Andes to the Pacific Ocean. Particle induced X-ray emission (PIXE), was used to determine elemental concentrations, and enrichment factors were used to evaluate the significance of anthropogenic sources. The results indicate the presence of Si, Al and Fe as major components. Cu, Cr, Mn, Pb and Zn are the main trace elements. In the Aconcagua river basin, which has less mining activity, the elemental concentrations are within the range of normal crust. Instead, samples from Choapa and Cachapoal river basins present high enrichment factors, mainly in copper. This is consistent with the fact that copper mines operate in the area. A correlation of the values obtained to copper using ICP and PIXE technique was statistically acceptable. Therefore, determination of Cu in river sediment by PIXE allows identification of areas affected by mining activities in river basins of northern Chile.