2024-02-052024-02-052023-11-13NORONHA FILHO, Francisco Áureo.Variação sazonal isotópica de estrôncio e hidrogeoquímica dos sistemas aquíferos Barreiras e Marajó na borda leste da Bacia do Marajó. Orientador: Marco Antonio Galarza Toro 2023. xvii, 88 f. Dissertação (Mestrado em Geoquímica e Petrologia) - Instituto de Geociências. Programa de Pós-Graduação em Geologia e Geoquímica, Universidade Federal do Pará, Belém, 2023. Disponível em: https://repositorio.ufpa.br/jspui/handle/2011/16233 . Acesso em:.https://repositorio.ufpa.br/jspui/handle/2011/16233The two main aquifer systems used for consumption and supply in the metropolitan region of Belém-PA (RMB) are the Barreiras and Marajó aquifers, the latter was previously called Pirabas. Within the regional geological context, the interpretation of the existence of the Eastern Edge of the Marajó Basin and the Marajó Formation in the RMB brought interesting discussions that can contribute to greater detail and understanding of the local hydrogeology. As well as assisting in the interpretation and integration of similar works previously developed. Since previous work has demonstrated distinct behaviors of strontium isotopic geochemistry. In this way, this work addresses this topic by bringing together previous and current information and discussing new propositions. To this end, hydrogeochemical characterization and isotopic geochemical characterization of strontium were carried out in the Barreiras and Marajó aquifers in the municipalities of Benevides, Marituba and Santa Izabel. The main objective was to understand the seasonal dynamics of interaction between the Barreiras and Marajó aquifer systems, identifying the meteoric water recharge processes and the mixing proportions between the Barreiras and Marajó aquifers. Groundwater samples were collected in 15 wells, 09 from the Barreiras aquifer and 06 from the Marajó aquifer in the municipalities of Marituba, Benevides and Santa Izabel do Pará in the RMB. Sampling took place during 2013, bimonthly, covering the annual hydrological cycle and the seasonality of the rainiest (December-May) and least rainy (June-November) periods. The analyzes of the 87Sr/86Sr isotopic ratio in groundwater samples were carried out at the Isotopic Geology Laboratory of the Institute of Geosciences (PARÁ-ISO) using the High Resolution Multicollector Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS, Neptune) according to the methodology proposed by Bordalo et al. in 2007. The hydrochemical analyzes were reproduced in accordance with the standard methodologies for water analysis of the American Public Health Association, APHA of 1995 and the National Water Agency of 2011 in the Hydrochemistry Laboratory of the Institute of Geosciences. For total iron, the determination was through spectrophotometry. The 1964 Grasshoff method was used for silica analysis. Using liquid chromatography, the main cations (Na+, K+, Mg2+ e Ca2+) and anions (Cl–,HCO3-, NO3–e SO4 2–) were determined using the DIONEX DX-120 ion chromatograph. The Barreiras aquifer presented high concentrations of nitrate associated with free aquifers, acidic pH and sodium chloride facies with an 87Sr/86Sr isotopic ratio that is more radiogenic in the less rainy period, similar to continental rocks and less radiogenic, similar to meteoric waters in the rainier period, suggesting the influence of the processes recharge. The Marajó aquifer presented confined behavior, neutral pH and calcium bicarbonate facies with some differences in the ion signature compared to the Pirabas aquifer. The 87Sr/86Sr ratios of the Marajó aquifer were less radiogenic and similar to macrofossils from the Pirabas Formation. It also showed small variations in isotopic ratios in both seasonal periods, which suggest a greater mixing ratio with the Barreiras aquifer in the rainiest period. The modeling results estimate that there is a greater contribution of meteoric water in the rainiest period in the Barreiras aquifer. Just as there is a greater proportion of mixing with the Barreiras aquifer in the Marajó aquifer in the rainiest period. The use of strontium isotopic geochemistry and the 87Sr/86Sr ratio associated with hydrogeochemistry for water mixing modeling proved to be an effective tool by presenting results that agree with each other.Acesso AbertoAttribution-NonCommercial-ShareAlike 3.0 Brazilhttp://creativecommons.org/licenses/by-nc-sa/3.0/br/Razão 87Sr/86SrMistura de águas subterrâneasHidrogeoquímicaIsótopos de estrôncioHidrogeologiaDissertaçãoCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIASGEOCRONOLOGIA E GEOQUÍMICA ISOTÓPICAGEOQUÍMICA E PETROLOGIA