Efeito da urbanização nas características geoquímicas da Laguna de Carapebus, Serra/ES

Abstract

ICOLLs are extremely sensitive to human intervention especially in relation to stress associated with the enrichment of nutrients and contaminants. Thus, trace and major elements (measured by ICP-MS and XRF), organic matter, total organic carbon, C/N ratio, total nitrogen, total sulfur and phosphorus were determined on a sediment core from the Carapebus lagoon, Serra, ES, Brazil, aiming to identify significant anthropogenic influences associated with the evolution of land use in the hydrographic basin of this urbanized ICOLL. This lagoon has undergone a transition in the origin of deposited sediment that motivated a change in its hydrodynamics. The C/N ratio results indicated that the deposited sediment was mainly derived from plankton at a first moment, then the main source was plants of higher plants, consistent with the large deforestation that occurred in the basin, finally the lagoon became heavily influenced by the discharge of domestic sewage. As for hydrodynamics, the disordered urban growth in the basin motivated the more frequent closure of the lagoon bar, which is currently open mechanically to avoid flooding during rainy periods. That transition was accompanied by untreated sewage discharge leading to an organic and metal enrichment in recent years. Elements that showed an increment in recent years were Ag (max. 1.44 mg.kg-1 ), Cd (max. 0.42 mg.kg-1 ), Cr (max. 60.78 mg.kg-1 ), Cu (max. 22.32 mg.kg-1 ), Pb (max. 3.73 mg.kg-1 ), Se (max. 12.93 mg.kg-1 ) and Zn (max. 41.24 mg.kg-1 ). Thus, this study alerts to chemical and physical changes in ICOLLs derived from deforestation and urbanization.