Accumulation of metals in sediments from a water catchment area for supply in Southern Brazil

Abstract

Heavy metals are more often becoming a problem to living beings due to their ability to bind organically in processes of bioaccumulation and biomagnification, as well to the natural environment where it can cause pollution and punctual or diffuse contamination. However, chemical elements that compound the heavy metal class are essential in small quantities for living organisms since they are natural components that are also contained in rocks and soils, which after dissolution processes may decay and be available in the ground and water. Therefore, the present study aimed to evaluate the levels of Fe and Mn dissolved in the water of the Epaminondas Hydrographic Basin, located in the municipality of Pelotas, RS. Environmental indexes were used to indicate whether the observed levels are from a natural or anthropic source and whether these levels are already contaminating the environment. Suspended and bottom sediments samples were collected from the basin at five different locations. The chemical description of these sediments was carried out based on their Cu, Fe, Mn, and Zn contents, Geoaccumulation Index, Factor of Enrichment, Contamination Factor, Degree of Contamination, Modified Degree of Contamination, and Pollutant Load Index. After elaborating on the proposed indexes, the heavy metal levels were deemed non-contaminant elements, classified as originated from a natural source.