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- Pham, M. K., et al.
(författare)
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A new Certified Reference Material for radionuclides in Irish sea sediment (IAEA-385)
- 2008
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Ingår i: APPLIED RADIATION AND ISOTOPES. - : Elsevier BV. - 1872-9800 .- 0969-8043. ; 66:11, s. 1711-1717
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Konferensbidrag (refereegranskat)abstract
- A new Certified Reference Material (CRM) for radionuclides in sediment (IAEA-385) is described and the results of the certification process are presented. Eleven radionuclides (K-40, Cs-137, Ra-226, Ra-228, Th-230, Th-232, U-234, U-238, Pu-238, Pu239+240 and Am-241) have been certified and information mass activities with 95% confidence intervals are given for seven other radionuclides (Sr-90, Pb-210(Po-210), U-235, Pu-239, Pu-240 and Pu-241). Results for less frequently reported radionuclides (Co-60, Tc-99, Cs-134, Eu-155, Ra-224 and Np-239) and information on some activity and mass ratios are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in sediment samples, for the development and validation of analytical methods and for training purposes. (C) 2008 IAEA. Published by Elsevier Ltd. All rights reserved.
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- Bordiga, Manuela, et al.
(författare)
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Microfossil evidence for trophic changes during the Eocene-Oligocene transition in the South Atlantic (ODP Site 1263, Walvis Ridge)
- 2015
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 11:9, s. 1249-1270
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Tidskriftsartikel (refereegranskat)abstract
- The biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene-Oligocene transition was investigated at a high resolution at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, southeast Atlantic Ocean) and compared with a lower-resolution benthic foraminiferal record. During this time interval, global climate, which had been warm under high levels of atmospheric CO2 (pCO(2)) during the Eocene, transitioned into the cooler climate of the Oligocene, at overall lower pCO(2). At Site 1263, the absolute nannofossil abundance (coccoliths per gram of sediment; N g(-1)) and the mean coccolith size decreased distinctly after the E-O boundary (EOB; 33.89 Ma), mainly due to a sharp decline in abundance of large-sized Reticulofenestra and Dictyococcites, occurring within a time span of similar to 47 kyr. Carbonate dissolution did not vary much across the EOB; thus, the decrease in abundance and size of nannofossils may reflect an overall decrease in their export production, which could have led to variations in the food availability for benthic foraminifers. The benthic foraminiferal assemblage data are consistent with a global decline in abundance of rectilinear species with complex apertures in the latest Eocene (similar to 34.5 Ma), potentially reflecting changes in the food source, i.e., phytoplankton. This was followed by a transient increased abundance of species indicative of seasonal delivery of food to the sea floor (Epistominella spp.; similar to 33.9-33.4 Ma), with a short peak in overall food delivery at the EOB (buliminid taxa; similar to 33.8 Ma). Increased abundance of Nuttallides umbonifera (at similar to 33.3 Ma) indicates the presence of more corrosive bottom waters and possibly the combined arrival of less food at the sea floor after the second step of cooling (Step 2). The most important changes in the calcareous nannofossil and benthic communities occurred similar to 120 kyr after the EOB. There was no major change in nannofossil abundance or assemblage composition at Site 1263 after Step 2 although benthic foraminifera indicate more corrosive bottom waters during this time. During the onset of latest-Eocene-earliest-Oligocene climate change, marine phytoplankton thus showed high sensitivity to fast-changing conditions as well as to a possibly enhanced, pulsed nutrient supply and to the crossing of a climatic threshold (e.g., pCO(2) decline, high-latitude cooling and changes in ocean circulation).
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| 4. |
- Pham, M. K., et al.
(författare)
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A new reference material for radionuclides in the mussel sample from the Mediterranean Sea (IAEA-437)
- 2010
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 283:3, s. 851-859
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Tidskriftsartikel (refereegranskat)abstract
- A new Reference Material (RM) for radionuclides in mussel (Mytilus galloprovincialis) from the Mediterranean Sea (IAEA-437) is described and the results of the certification process are presented. Four radionuclides (K-40, U-234, U-238, and Pu239+240) have been certified, and information values on massic activities with 95% confidence intervals are given for nine radionuclides (Cs-137, Pb-210(Po-210), Ra-226, Ra-228, Th-228, Th-230, Th-232, U-235, and Am-241). Results for less frequently reported radionuclides (Sr-90, I-129, Pu-238, Pu-239, and Pu-240) are also reported. The RM can be used for quality assurance/quality control of the analysis of radionuclides in mussel samples, for the development and validation of analytical methods and for training purposes. The material is available in 200 g units.
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