NICOLE PEREIRA DE LIMA

NICOLE PEREIRA DE LIMA

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Avaliação do teor de Cr ao longo do sítio do Observatório Amazônico de Torre Alta (ATTO)
2024 - TAPPIZ, BRUNO; SILVA, PAULO S.C. da; OSTERMANN, CAROLINE K.; LIMA, NICOLE P. de; CARVALHO, ELIAS F. de; BUSTILLOS, JOSE O.V.
A fração mássica do elemento Cr foi analisada amostras de solo coletadas ao longo do sítio do Observatório Amazônico de Torre Alta (ATTO), localizado na Reserva de Desenvolvimento Sustentável (RDS) do Uatumã, a aproximadamente 150 km ao nordeste da cidade Manaus, estado do Amazonas. O sítio ATTO encontra-se em uma região sem desmatamento e com pouca influência antropogênica onde estão instaladas duas torres (as torres ATTO e Instante) dedicadas a pesquisas atmosféricas. A RSD Uatumã é caracterizada por diferentes ecossistemas: (i) Terraço, uma área florestal sazonalmente inundada por água negras (Igapó) ao longo do canal principal e afluentes menores do rio Uatumã; (ii) Platô, região de floresta densa em terras altas e não inundadas (Terra Firme); e (iii) Campina (cerrado em solos de areia branca) que inclui uma zona de transição denominada Campinarana (florestas em solo de areia branca), situadas principalmente entre os Terraços de rio e a encosta em direção ao Platô. Com o intuito de avaliar o teor de Cr ao longo do sítio ATTO, foram coletadas amostras nas 3 diferentes regiões que compõe o sítio de estudo. Ao todo, foram coletadas amostras de solo em 6 pontos do Terraço, 4 na Campina e 6 no Platô, totalizando 87 amostras. As amostras foram analisadas no Instituto de Pesquisas Energéticas e Nucleares (IPEN), pela técnica de Análise por Ativação Neutrônica Instrumental (INAA). Os teores médios de Cr obtidos, em mg/kg, por ponto, para a região do Terraço foram: T1 = 29 ± 1; T2 = 37 ± 1; T3 = 76 ± 2; T4 = 28 ± 1; T5 = 42 ± 1; T6 = 34 ± 1; para Campina e Campinarana: C1 = 2,7 ± 0,1; C2 = 3,4 ± 0,2; C3 = 2,1 ± 0,1; C4 = 2,1 ± 0,2; e por fim, para o Platô: P1 = 85 ± 3; P2 = 69 ± 2; P3 = 66 ± 2; P4 = 102 ± 3; P5 = 101 ± 3; P6 = 99 ± 3. De forma geral, é possível afirmar que os menores teores desse elemento ocorrem na região da Campina e os maiores na região do Platô. Esse comportamento pode ser justificado pela composição geológica predominante em cada região e pelo tipo de intemperismo que afeta a região, denominado intemperismo laterítico. Esse intemperismo ocorre predominantemente em regiões tropicais úmidas, em que ocorre uma lixiviação preferencial dos elementos mais solúveis (como por exemplo os alcalinos e alcalinos terrosos) enquanto que os elementos menos solúveis como o Cr, ficam presos e são enriquecidos no solo. O entendimento da dinâmica do solo na região, por meio do estudo da sua composição elementar, pode contribuir para a compreensão da interdependência existente no sistema solo-biosfera-atmosfera e desse com a relação da floresta com os possíveis efeitos climáticos.
Assessment of 238U and 226Ra activity concentration along the Amazon Tall Tower Observatory site
2023 - TAPPIZ, B.; SILVA, P.S.C.; OSTERMANN, C.K.; LIMA, N.P.; BRAGUIN, L.N.M.; BOTIA, S.; LEVIN, I.; BUSTILLOS, O.V.
The Amazon Tall Tower Observatory (ATTO) site is a region located within the Uatumã Sustainable Development Reserve (USRD), approximately 150 km northeast of Manaus city, in the Brazilian state of Amazonas. At the ATTO site, there are 3 tall towers, which are used for studies on the Amazon rainforest and its interaction with the soil and the atmosphere. The activity concentration of 238U and 226Ra was determined in soil samples collected in the footprint of the ATTO site by gamma spectrometry. The activity concentration of these radionuclides is important for understanding the 222Rn exhalation rate and 222Rn flux from soils. Knowledge of the 222Rn flux at the ATTO site can be useful for applications in atmospheric research, e.g., the 222Rn tracer method can be used to estimate local and regional emissions of greenhouse gasses; simulating 222Rn transport is a powerful tool for evaluation and validation of transport schemes in atmospheric chemical transport models. In this study, 39 samples collected from 13 sampling sites along a transect from the ATTO site to the river were analyzed. The highest activity concentrations were found in the Igapó forest (69 ± 2 Bq/kg for 238U and 47 ± 5 Bq/kg for 226Ra), a region near the Uatumã river with prevailing flooded black-water forest, whereas the lowest activity concentrations occurred in the Campina (Savanna on white-sand soils) and Campinanara (white-sand forest) ecosystems (18 ± 1 Bq/kg for 238U and 13 ± 2 Bq/kg for 226Ra), a transition area located between river terraces and the Terra Firme forest.
Comparison of 238U mass fraction measured by ICP–MS and Instrumental Neutron Activation Analysis techniques
2022 - TAPPIZ, BRUNO; SILVA, PAULO S.C. da; OSTERMANN, CAROLINE; LIMA, NICOLE P. de; ANDRADE, MARIANA N. de; BUSTILLOS, OSCAR V.
Introduction: Uranium is an element present in ambient air, water, soil and rocks [1]. The most abundant natural radioisotope of this actinide (238U) produces in its chain decay the radionuclide 222Rn [2], which is a tracer for atmospheric mixing and transport model validations [3]. The 238U activity concentration in superficial soil samples is a crucial parameter for some 222Rn flux map modeling methodologies [4]. Methods: In this study, 18 superficial soil samples were analyzed. The content of 238U was assessed using two techniques: (i) by the comparative method of the Instrumental Neutron Activation Analysis (INAA) [5] and by ICP–MS (ELAN 6000, PerkinElmer) [6]. Certified Reference Materials (CRM) SRM 1646a Estuarine Sediment and USG STM–2 were used both as comparators in the INAA technique and to ensure quality control. The normality and homoscedasticity of the data were evaluated. Finally, the Mann- Whitney U test [7] was used to assess whether or not there is a significant difference (α = 0.05) between the two techniques. Results: The z-score was calculated to ensure quality control. Z-scores values was obtained by the Modified Horwitz Equation [8], which takes into account the order of magnitude of the content of the analyte and is independent of the CRM uncertainties, unavailable for the CRM used. The z-score values obtained (n = 3) for the radionuclide 238U were 0.5 for the CRM USG STM–2 and -0.4 for SRM 1646a. The z-scores obtained are smaller than 2 therefore they are considered satisfactory [9]. Regarding the statistical parameters of the comparison between the techniques, the normality (Shapiro Wilk) was not verified (p = 0.02 for ICP-MS and p = 0.03 for INAA). The p-value for the test for equal variances (F test) was 0.71 Mann-Whitney U test was used instead of Student’s test due to the non-verification of the normality parameter in the data. The p-value from the Mann-Whitney test (0.51) indicates that there is no significant difference between the 238U content measured by the two techniques. Conclusions: Statistical analysis showed that there is no significant difference between the 238U mass fraction measured by the ICP–MS and the INAA – comparative method. In the future, certified reference materials will also be assessed by ICP–MS in order to corroborate this statistical comparison from a metrological point of view.
Local crystalline structure of doped semiconductor oxides characterized by perturbed angular correlations
2022 - BURIMOVA, ANASTASIA; CARBONARI, ARTUR W.; LIMA, NICOLE P. de; MIRANDA FILHO, ARNALDO A.; SOUZA, ALEXANDRE P. dos S.; SALES, TATIANE da S.N.; FERREIRA, WANDERSON L.; PEREIRA, LUCIANO F.D.; CORREA, BRUNO S.; SAXENA, RAJENDRA N.
Doping semiconductor oxides with trace amounts of non-native elements can improve their properties such as bandgap and conductivity. The lack of local techniques makes the precise characterization of these materials difficult. Among the few techniques capable of providing local characterization, those based on hyperfine interactions at probe nuclei have the advantage of being well established, probing the material homogeneously and completely, thus investigating different regions of material. Some of these techniques are also quite sensitive even at extremely low dopant concentrations. The perturbed angular correlation technique, combined with first-principles calculations, has recently been shown to be a powerful method for characterizing doped semiconductor oxides. In this paper, we present a brief review of the unique information extracted from the semiconductor investigation with such a complex approach, including semiconductor oxides doped with cadmium and other elements. A strong relationship between the local environment, including electronic structure, and the nature of the dopant and the native element of the doped oxides is also shown.
Synthesis and TDPAC characterization of multiferroics
2021 - LIMA, N.P.; BURIMOVA, A.; SOUZA, A.P.S.; LEITE NETO, OSMAR F.S.; CARBONARI, A.W.