Towards a complete 14C AMS facility at the Universidade Federal Fluminense (Niterói, Brazil): Sample preparation laboratory tests

Anjos, R. M.; Macario, Kita C. D.; Gomes, P.R.S.; Linares, R.; Queiroz, Emerson F.; Carvalho, C. A. A. de

doi:10.1016/j.nimb.2012.01.031

Cited by 11 publications

(4 citation statements)

References 21 publications

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“…After bleaching, the holocellulose was rinsed 3 times with UP water and dried at 60°C. After combustion of the pretreated samples at 900°C for 3 hr, the CO 2 evolved was cryogenically purified under vacuum lower than 10 -3 Torr (Anjos et al 2013). Graphitization was performed following the Zinc (Zn), titanium hydride (TiH 2 ) and iron (Fe) catalyst, with modified reduction at 550°C during 7 hr in a muffle (Xu et al 2007;Macario et al 2015).…”

Section: Measurementsmentioning

confidence: 99%

Annually Verified Growth of Cedrela Fissilis from Central Brazil

et al. 2019

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Given the difficulty in obtaining robust chronologies from tree rings in tropical regions, the search for appropriate species is very important. Both dendrochronology and radiocarbon (14C) measurements are required to validate the use of any specific tree. Some species have proved to be reliable for representing atmospheric 14C concentration over time, such as Cedrela fissilis and Araucaria angustifolia. However, not only the species have to be validated, but also different climatic conditions may result in different growth patterns for the same species. In this work, we study the annual growth rings of Cedrela fissilis from a dry tropical forest patch typical of a highly seasonal climate in central Brazil. 14C accelerator mass spectrometry (AMS) was used to compare the isotopic ratios of tree rings with the 14C concentrations in the atmosphere during the nuclear tests based on curve Bomb13SH 1-2. Results are similar to the bomb peak curve within the period from 1958 to 1980 AD and serve as a crucial test for the cross-dating analyses using the skeleton plot technique.

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Section: Measurementsmentioning

confidence: 99%

Annually Verified Growth of Cedrela Fissilis from Central Brazil

et al. 2019

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“…The establishment of the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF), the first radiocarbon ( 14 C) accelerator mass spectrometry (AMS) dedicated facility in South America (Anjos et al 2013; Macario et al 2013, 2015a), and subsequent research about the marine reservoir effect (MRE), particularly on the southeastern Brazilian coast (Macario et al 2015b, 2016a, 2018; Carvalho et al 2015; Alves et al 2015a, 2015b), have contributed to improve 14 C-based studies on archaeological shellmounds. The materials that have traditionally been used for 14 C analysis are charcoal, seed, shell (Lima et al 2004; Angulo et al 2007; Macario et al 2014, 2015b; Alves et al 2015a; Carvalho et al 2015) and human bones (e.g.…”

Section: Introductionmentioning

confidence: 99%

Otolith-Based Chronology of Brazilian Shellmounds

et al. 2019

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The radiocarbon (14C) chronology of hunter-fisher-gatherers’ archaeological settlements along the Brazilian coast is usually based on mollusk shells, charcoal from hearths, and eventually human bones. However, fish otoliths are found in several archaeological contexts and may represent a reliable option as a chronological record. In this work, we compare the 14C dates of whitemouth croakers (Micropogonias furnieri) otoliths with dates obtained from other materials (shell and charcoal), collected from shellmounds on the coast of Rio de Janeiro, with the aim of improving the accuracy in the 14C dating of Brazilian shellmounds, strengthening the comprehension of the native populations’ occupational trends and the coeval palaeoceanographic context. Based on x-ray diffraction results for archaeological otoliths, their geochemical composition indicates minimal diagenesis effect over time even under burial conditions in the studied sites. The comparison between otolith dates and dates obtained from other proxies revealed similar results but with decreased deviations in otolith dates in all of the studied sites.

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“…Seven years have passed since the establishment of the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF), the last 4 years of which include the operation of a 250kV NEC Single Stage Accelerator (SSAMS) system at the Physics Institute, in Niterói, Rio de Janeiro State, Brazil. Over this period, more than 4000 samples have been measured, including unknown age and quality control samples (Anjos et al 2013; Macario et al 2013, 2015; Linares et al 2015). Currently, samples of wood, charcoal, soil, and carbonates are routinely prepared and measured in our facility.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Amount of Zinc in the Graphitization Reaction for Radiocarbon AMS Measurements at LAC-UFF

et al. 2016

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The Radiocarbon Laboratory of the Universidade Federal Fluminense, in Brazil, has been successfully applying the zinc reduction method for graphitization of carbon samples since the development of its early protocols in 2009. Successive methodological research aiming to improve and, ultimately, optimize the precision and accuracy of our results indicates that graphitization temperatures as low as 460°C promote erratic 13C isotopic fractionation, but an approximately constant fractionation of about –5‰ is achieved at 520°C. In this work, we present isotope ratio mass spectrometry (IRMS) δ13C results for 14C reference materials graphitized at 550°C with variable amounts of zinc. Based on the results obtained from the addition of 20, 35, and 50 mg of zinc, we conclude that a slightly lower variation in 13C isotope fractionation during graphitization is obtained with less zinc. Moreover, the average isotopic fractionation is not altered by increasing the graphitization temperature from 520°C to 550°C.

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Towards a complete 14C AMS facility at the Universidade Federal Fluminense (Niterói, Brazil): Sample preparation laboratory tests

Cited by 11 publications

References 21 publications

Annually Verified Growth of Cedrela Fissilis from Central Brazil

Annually Verified Growth of Cedrela Fissilis from Central Brazil

Otolith-Based Chronology of Brazilian Shellmounds

Optimization of the Amount of Zinc in the Graphitization Reaction for Radiocarbon AMS Measurements at LAC-UFF

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