環境汚染と気候変動

抽象的な

Spatial and Temporal Variation of Heavy Metals Contamination in Recent Sediments from Barigui River Basin, South Brazil

Karina Scurupa Machado, Paulo AI Ferreira, Juliane Rizzi, Rubens Figueira and Sandro Froehner

Heavy metals (Cd, Cr, Cu, Pb, Mn and Zn) and artificial radionuclides (¹³⁷Cs and ²¹⁰Pb) were investigated in three sediment cores from the Barigui river Basin, South Brazil, in order to reconstruct the spatial and temporal evolution of the pollution by heavy metals. According to the reference standards established by the Canadian quality guidelines, the area presents levels of pollution considered significant. Enrichment factors (EFs) were calculated to estimate the level of contamination in these sediment storages over time. EFs showed a steady increase from bottom to core top throughout the years and this pattern is present in all cores. The magnitude of the EFs suggests that higher contamination is observed in the central and lower parts of the basin, due to regional history and geographic characteristics. The evolution of the contamination by heavy metals is more intense as from the middle of the 19^th due to the high demographic, economic and industrial growth in the region. This study clearly contributes to understand when the anthropogenic activities became harmful for the environment in South Brazil, which events were more significant and which parts of the studied area were more affected.