http://hdl.handle.net/10150/635062 2026-03-10T00:50:48Z 2026-03-10T00:50:48Z Porter, Antun Obelić, Bogomil Krajcar Bronić, Ines http://hdl.handle.net/10150/654388 2021-02-15T01:25:19Z 2010-01-01T00:00:00Z

ZAGRADA—The New Zagreb Radiocarbon Database Porter, Antun; Obelić, Bogomil; Krajcar Bronić, Ines After introducing the liquid scintillation counting (LSC) method and graphite target preparation for accelerator mass spectrometry (AMS) measurements in the Zagreb Radiocarbon Laboratory, the existing database software designed only for gas proportional counting (GPC) (using a DOS operating system) could not satisfy the requirements for parallel conduction of several techniques. This has been enabled recently by the development of the new relational database ZAGRADA, which--using SQL scripts and constraints defined by primary and foreign keys--enforces high data integrity and provides better performances in data filtering and sorting. The structural scheme of this database conceptually comprises 4 basic modules with data on the samples, chemical pretreatment and preparation, measurements and data on the final results. A user-friendly graphical user interface has been designed to perform various actions and data manipulation to the database. The implementation of a new database for 14C samples has significant contribution to scientific research performed in the Radiocarbon and Tritium Laboratory and to quality assurance and quality control, and will enable better and easier communication with customers. From the 20th International Radiocarbon Conference held in Kona, Hawaii, USA, May 31-June 3, 2009.

2010-01-01T00:00:00Z Druffel, Ellen R. M. Beaupré, Steven Griffin, Sheila Hwang, Jeomshik http://hdl.handle.net/10150/654382 2021-02-15T01:21:02Z 2010-01-01T00:00:00Z

Variability of Dissolved Inorganic Radiocarbon at a Surface Site in the Northeast Pacific Ocean Druffel, Ellen R. M.; Beaupré, Steven; Griffin, Sheila; Hwang, Jeomshik We report radiocarbon measurements of dissolved inorganic carbon (DIC) in surface water samples collected daily during 12 cruises to Station M in the northeast Pacific off central California. Individual surface ∆14C values ranged from 22 to 70 over 10 yr. Variability of average cruise values is highest during winter likely due to increased mixing. A general decrease of ∆14C values was observed at a rate of about 3 per year between 1994 and 2004, about half of that in atmospheric CO2 during this period (Levin and Kromer 2004). The ∆14C results ranged from 2-18 during individual cruises and were often significantly larger than the total uncertainty for individual measurements (3.9). This indicates that a single ∆14C result from a surface site is not sufficient to capture the true variability of ∆14C in the surface ocean. From the 20th International Radiocarbon Conference held in Kona, Hawaii, USA, May 31-June 3, 2009.

2010-01-01T00:00:00Z Quarta, G. Pezzo, M. I. Marconi, S. Tecchiati, U. D'Elia, M. Calcagnile, L. http://hdl.handle.net/10150/654386 2021-02-15T01:23:58Z 2010-01-01T00:00:00Z

Wiggle-Match Dating of Wooden Samples from Iron Age Sites in Northern Italy Quarta, G.; Pezzo, M. I.; Marconi, S.; Tecchiati, U.; D'Elia, M.; Calcagnile, L. Archaeological excavations carried out at the sites of Laion/Lajen (Bolzano/Bozen) and Stufles-Oberegger (Bressanone/Brixen) in northern Italy uncovered well-preserved wooden samples in cultural layers archaeologically dated to the Iron Age. From the 2 sites, different wooden samples were recovered that were well preserved enough to allow clear identification of the tree species and of the ring structure. Among the different wooden samples, 2 were selected for radiocarbon analyses: from Laion/Lajen, a beam with an unbroken sequence of 158 rings; from Stufles-Oberegger, a combusted trunk with a sequence of 217 rings. Both samples were identified as Larix decidua species. From each sequence, single rings were selected and submitted for accelerator mass spectrometry (AMS) 14C dating analysis at CEDAD. Conventional 14C ages were then calibrated to calendar ages using the IntCal04 atmospheric data set, while the statistical constraints resulting from the defined ring sequence were used to develop a wiggle-matching approach by making use of the Bayesian analysis functions available in OxCal. The obtained results are an important contribution in refining the chronology of the studied sites. From the 20th International Radiocarbon Conference held in Kona, Hawaii, USA, May 31-June 3, 2009.

2010-01-01T00:00:00Z Ding, P. Shen, C. D. Wang, N. Yi, W. X. Ding, X. F. Fu, D. P. Liu, K. X. Zhou, L. P. http://hdl.handle.net/10150/654376 2021-02-15T01:17:27Z 2010-01-01T00:00:00Z

Turnover Rate of Soil Organic Matter and Origin of Soil 14CO2 in Deep Soil from a Subtropical Forest in Dinghushan Biosphere Reserve, South China Ding, P.; Shen, C. D.; Wang, N.; Yi, W. X.; Ding, X. F.; Fu, D. P.; Liu, K. X.; Zhou, L. P. This paper examines the carbon isotopes (13C, 14C) of soil organic carbon (SOC) and soil CO2 from an evergreen broadleaf forest in southern China during the rainy season. The distribution of SOC 13C, and SOC content with depth, exhibits a regular decomposition of SOC compartments with different turnover rates. Labile carbon is the main component in the topsoil (0-12 cm) and has a turnover rate between 0.1 and 0.01 yr-1. In the middle section (12-35 cm), SOC was mainly comprised of mediate carbon with turnover rates ranging between 0.01 and 0.025. Below 35 cm depth (underlayer section), the SOC turnover rate is slower than 0.001 yr-1, indicating that passive carbon is the main component of SOC in this section. The total production of humus-derived CO2 is 123.84 g C m-2 yr-1, from which 88% originated in the topsoil. The middle and underlayer sections contribute only 10% and 2% to the total humus-derived CO2 production, respectively. Soil CO2 13C varies from -24.7 to -24.0, showing a slight isotopic depth gradient. Similar to soil CO2 13C, ∆14C values, which range from 100.0 to 107.2, are obviously higher than that of atmospheric CO2 (60-70) and SOC in the middle and underlayer section, suggesting that soil CO2 in the profile most likely originates mainly from SOC decomposition in the topsoil. A model of soil CO2 ∆14C indicates that the humus-derived CO2 from the topsoil contributes about 65-78% to soil CO2 in each soil gas sampling layer. In addition, the humus-derived CO2 contributes ~81% on average to total soil CO2 in the profile, in good agreement with the field observation. The distribution and origin of soil 14CO2 imply that soil CO2 will be an important source of atmospheric 14CO2 well into the future. From the 20th International Radiocarbon Conference held in Kona, Hawaii, USA, May 31-June 3, 2009.

2010-01-01T00:00:00Z