Sediment Geochemistry and Climatic Influences in a River Influenced by Former Mining Activities: the Case of Ribeira de Iguape River, SP-PR, Brazil

The Ribeira de Iguape River (RIR) was historically contaminated by residues from mining activities. These activities ceased in the late 1990’s, but the residues remained deposited along the river banks. This study aimed to evaluate the sediment characteristics of the RIR in different hydro-meteorological conditions and detect eventual changes in the geochemistry. Three sampling surveys were conducted, in which sediments were collected in 6 sites, and then analyzed for sediment textures and metals concentrations. Sediments were predominantly sandy, and samples collected downstream to the mining areas tended to be enriched by metals, especially Pb, Cr, Cu, Ni and Zn. Concentrations of metals in sediments tended to be higher after rainstorm episodes, evidencing the pollution sources are not totally controlled and that the stormwater runoff may carry metals to the RIR.