GEOQUÍMICA DAS ÁGUAS SUPERFICIAIS E A RELAÇÃO COM AS FORMAÇÕES

• Ano de defesa: 2021
• Autor(a) principal: Nogueira, Gabriel Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Geografia; Centro de Ciências Humanas e Naturais; UFES; Programa de Pós-Graduação em Geografia
• Palavras-chave em Português: Ilha; ilha vulcânica; geoquímica; hidrogeoquímica; Ilha da Trindade; subject.br-rjbn; Geografia
• Link de acesso: http://repositorio.ufes.br/handle/10/14273

This research investigated the temporal occurrence of some chemical elements and physicochemical parameters in the superficial waters from a volcano isle in a tropical climate (Trindade Island), establishing a relationship between the geochemistry of the geological substrate and the superficial unconsolidated formations (soils). To that end, the research area was the Córrego da Captação watershed, in the eastern Trindade Island/Brazil. Seasonal measurements of physicochemical parameters and flow rates were made on March, August, September and October of 2019 and forty water samples were collected from the Córrego da Captação between August and October of 2019. The rainfall was also monitored in three different places on the isle (east side, the summit and west side). In the laboratory, the water samples were analyzed on ICP-MS to obtain the concentrations of total metals (Ca, Mg, Zn, Sr, Al, Fe, Ba, Mn, Cu, V, Be, As, Cd, Ni, Pb, Cr e Ag). Correlation analysis was done between the total metals and the geochemistry of the watershed’s lithology, soils, and the rainfall. The results show an uneven distribution of rainfall between the east side, the summit and the west side of Trindade Island. The average flow rate of the Córrego da Captação were 11.186 l/s, with the highest average in March and the lowest in September. The results of the turbidity and total suspended sediments parameters followed the flow rate, while the electrical conductivity (EC) and total dissolved solids (TDS) showed an inversely proportional behavior. Thus, it is understood that in the rainier months on Trindade Island the surface erosion processes predominate, and in the drier months there is more chemical erosion processes. Calcium was the element with the highest concentrations in surficiale water followed by magnesium. The high concentrations of Sr, Zn, Cu e V show a possible contribution of birds to the unconsolidated surface formations. The correlations between total metals concentrations and accumulated rainfall index show that the superficial waters from a volcano island in tropical climate (Trindade Island) remain underground for weeks and then flow to the streams. This can be provenby the high values of TDS and EC. In conclusion, this research verified the existence of differential erosive processes acting on volcanic island in tropical climate (Trindade Island) controlled by the rainfall rates throughout the year.