Calibration and use of well-type germanium detectors for low-level gamma-ray spectrometry of sediments using a semi-empirical method

Díaz-Asencio, Misael; Sánchez-Cabeza, Joan-Albert; Ruíz-Fernández, Ana Carolina; Corcho-Alvarado, J.A.; Pérez-Bernal, Libia Hascibe

doi:10.1016/j.jenvrad.2020.106385

Cited by 17 publications

(3 citation statements)

References 24 publications

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“…The radiochronology of the upper core segment (0–20 cm) of the subcore Tehua XII E03 a was estimated through the 210 Pb age dating method at 1 cm resolution (Table S1). 210 Pb activities were determined at the laboratory of Isotopic Geochemistry and Geochronology at UNAM (Mexico) through high-resolution gamma ray spectrometry (HPGe well detector, Ortec-Ametek) as described by Díaz-Asencio et al (2020). For validation, 239,240Pu was determined in selected sediment samples by alpha spectrometry (Ortec-Ametek Alpha Spectrometry system) (Ruiz-Fernández et al, 2014).…”

Section: Methodsmentioning

confidence: 99%

Diatom-based paleoproductivity and climate change record of the Gulf of Tehuantepec (Eastern Tropical Pacific) during the last ~500 years

et al. 2023

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Changes in marine productivity of the last five centuries in the Gulf of Tehuantepec were investigated using a high-resolution record of diatoms, organic carbon (Corg), total nitrogen (TN), Ni/Al, and Cu/Al. The laminated sediments were dated by using 210Pb and 14C, with a bayesian age model providing a new Δ R = 247 ± 30 years for the bulk sediment. The Little Ice Age (LIA) (~1500 to ~1858 CE) was characterized by the predominance of cold-water and high productivity diatoms ( Chaetoceros spores, Thalassionema nitzschioides, Lioloma pacificum, Thalassiosira nanolineata, and Rhizossolenia setigera) and high values of geochemical productivity proxies. A transition period (~1860 to ~1919 CE) toward warmer conditions related to the end of the LIA and the beginning of the Current Warm Period (CWP), was indicated by the appearance of warm-water diatoms ( Neodelphineis pelagica, Thalassiosira tenera, and Rhizossolenia bergonii), as well as lower values of Corg, TN, Ni/Al, and Cu/Al. The most recent period of the CWP (~1920 CE to today) was characterized by the increased abundance warm-water taxa ( N. pelagica, Cymatodiscus planetophorus, T. tenera, Plagiogramma minus, Nitzschia interruptestriata, and R. bergonii), and by the prevalence of low values of Corg, TN, Ni/Al, and Cu/Al. These changes in productivity during the LIA and CWP were likely driven by changes in solar irradiance and the migration of the Intertropical Convergence Zone. This study highlights the spatial extent of the LIA in the Eastern Tropical North Pacific and contributes to the knowledge of the productivity response to climate in tropical regions.

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Section: Methodsmentioning

confidence: 99%

Diatom-based paleoproductivity and climate change record of the Gulf of Tehuantepec (Eastern Tropical Pacific) during the last ~500 years

et al. 2023

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“…Las medidas de 210 Pb por espectrometría de rayos gamma son más complejas y requieren cuidadosas y exhaustivas calibraciones para que los resultados sean fiables (Díaz-Asencio et al, 2020). Esto se debe a que el fotón gamma emitido por el 210 Pb es de baja energía, su probabilidad de emisión es de sólo 4,25% y puede ser fácilmente absorbido por la propia muestra que lo contiene (autoabsorción).…”

Section: Análisis Del 210 Pbunclassified

Datación de sedimentos recientes utilizando radionucleidos de vida corta

Bilbao¹,

Gómez-Arozamena²,

Irabién³

et al. 2022

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Se presentan las características principales del método de datación de sedimentos recientes mediante el radioisótopo natural 210Pb y su validación utilizando radionucleidos artificiales tales como 137Cs y 239,240Pu. Se hace una revisión de los principios generales de esta metodología, se aportan recomendaciones prácticas para la recogida de testigos sedimentarios en el campo y su posterior procesamiento en el laboratorio, se describen diferentes técnicas analíticas utilizadas en la determinación de sus concentraciones y se explican brevemente varios modelos para la interpretación de los perfiles obtenidos. Por último, se incluyen ejemplos prácticos de su aplicación en secuencias sedimentarias procedentes de distintos ambientes marinos (estuario, bahía y plataforma continental) en el norte de la Península Ibérica.

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“…However, the 210 Pb ages may suffer from different biases and usually need to be verified using an independent method (Appleby 1998 ; Santschi and Rowe 2008 ; Corcho-Alvarado et al 2014 , Barsanti et al, 2020 ). For this purpose, other chronostratigraphic markers such as the global fallout radionuclides (e.g., 137 Cs, 239+240 Pu, and 241 Am) are commonly measured in sedimentary records (Appleby et al 1986 , Appleby et al 1991 , Lindahl et al 2010 , Díaz-Asencio et al 2016 , Díaz-Asencio et al, 2020c , Foucher et al 2021 ). Global fallout radionuclides are characterized by a distinct maximum in 1963, which is related to the period of higher intensity of nuclear weapons testing (Corcho-Alvarado et al 2014 ; Foucher et al 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Distribution and source of plutonium in sediments from the southern Gulf of Mexico

Corcho-Alvarado

Díaz-Asencio

Röllin

et al. 2022

Environ Sci Pollut Res

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Here, we report on new data (75 analyses) of plutonium (Pu) isotopes to elucidate activity concentrations, inventories, sources, and their transport from the ocean surface to the seafloor from a collection of six deep-sea sediment cores (depths ranging from 257 to 3739 m) in the southern Gulf of Mexico. Sediment cores collected from the continental shelf and upper slope region of the Gulf of Mexico showed 240Pu/239Pu ratios of 0.15 to 0.26, and 239+240Pu-inventories ranging from 14.7 to 33.0 Bq m−2. Inventories and ratios are consistent with global fallout Pu for this tropical region. In contrast, sediment cores collected from the lower slope region and abyssal plain showed low 240Pu/239Pu ratios of 0.07 to 0.13 and much lower 239+240Pu inventories below 6.8 Bq m−2. This implies that only a small fraction of the expected global fallout Pu has reached the deep-sea sediments. The low 240Pu/239Pu isotope ratios indicate that fallout from the Nevada testing site was an important source of Pu in deep-sea sediments, and that this Pu was likely more efficiently scavenged from the water column than Pu from global fallout. We estimated that up to 44% of the total inventory of 239+240Pu in deep-sea sediments is due to the Nevada source. Low values and a progressive decrease of 240Pu/239Pu ratios and 239+240Pu inventories with increasing water depth have been previously reported for the Gulf of Mexico. Analysis of Pu isotopes in two sediment traps from the upper slope regions shows 240Pu/239Pu ratios comparable to those observed in global fallout. These results indicate that global fallout Pu is currently the main source of Pu in sinking particles in the water column. Therefore, a significant fraction of global fallout Pu must still be present, either in a dissolved phase, or as biologically recycled material in the water column, or scavenged on the shelf and shelf break. Our results bring to light important questions on the application of Pu isotopes to establish sediment chronologies in deep-sea sediments, since global fallout features such as the 1963 maximum are not available.

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Calibration and use of well-type germanium detectors for low-level gamma-ray spectrometry of sediments using a semi-empirical method

Cited by 17 publications

References 24 publications

Diatom-based paleoproductivity and climate change record of the Gulf of Tehuantepec (Eastern Tropical Pacific) during the last ~500 years

Diatom-based paleoproductivity and climate change record of the Gulf of Tehuantepec (Eastern Tropical Pacific) during the last ~500 years

Datación de sedimentos recientes utilizando radionucleidos de vida corta

Distribution and source of plutonium in sediments from the southern Gulf of Mexico

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