14C Dating of Soil Organic Carbon (SOC) in Loess-Paleosol Using Sequential Pyrolysis and Accelerator Mass Spectrometry (AMS)

Radiocarbon ◽  
2013 ◽  
Vol 55 (2) ◽  
pp. 563-570 ◽  
Author(s):  
Peng Cheng ◽  
Weijian Zhou ◽  
Hong Wang ◽  
Xuefeng Lu ◽  
Hua Du

The chemical extraction of soil organic carbon (SOC) fractions from soils often does not produce satisfactory results for radiocarbon dating. In this study, a sequential pyrolysis technique was investigated. The soil was pyrolyzed at temperatures of 200, 400, 600, and 800 °C to partition organic carbon into pyrolytic volatile (Py-V) and pyrolytic residue (Py-R) fractions. The preliminary results show that the 14C dates of both fractions become progressively older as the pyrolysis temperature is increased. In addition, the ages of the Py-V fractions are consistently younger than the corresponding Py-R fractions extracted at the same temperature. Experimental results of known-age paleosol samples indicate that the Py-V fractions obtained between 600 and 800 °C yield the most reliable ages. This technique provides a new approach to improve the accuracy of 14C dating of loess-paleosol sequences.

Radiocarbon ◽  
2002 ◽  
Vol 44 (2) ◽  
pp. 591-595 ◽  
Author(s):  
Ken Mueller ◽  
Paul Muzikar

When using accelerator mass spectrometry (AMS) for radiocarbon dating, it is important to correct for carbon contamination that is added to the sample and the standard during chemical processing. We derive an equation for making this correction that generalizes previous work in several ways. We treat the case in which contaminating carbon is added during both the combustion step and graphitization step. Taking this two-stage contamination process into account is particularly important when only a fraction of the CO2 produced in the combustion is graphitized. We also allow for the fact that the 13C fractions of the sample, the standard, and the contaminants may be different.


Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 541-553 ◽  
Author(s):  
Yurij K Vasil'chuk ◽  
Alla C Vasil'chuk ◽  
Dieter Rank ◽  
Walter Kutschera ◽  
Jong-Chan Kim

The Duvanny Yar cross-section located in the Lower Kolyma River valley of Northern Yakutia (69°N, 158°E, height above the Kolyma River level 55 m), has been studied and dated in detail by radiocarbon. The sequence mainly consists of sandy loam sediments with large syngenetic ice wedges. Their width at the top is 1–3.5 m. Allochthonous organic material occurs in high content, concentrating as 0.5–0.7 m lenses. Shrub fragments, twigs, and mammoth bones are accumulated in peaty layers. Through interpolation based on a series of 14C dates, dating of the host sediments provides an approximate age for the ice wedges. The 14C dates of various types of organic material are sometimes very close, but not all in agreement. Therefore, the dates do not accurately show the age of the δ18O and δD plots. A new approach is developed to a 14C dating strategy of syncryogenic sediments with high admixture of allochthonous organic material. The main purpose of this study is to consider detection of inversions or disturbances in the syngenetic permafrost sediment at the Duvanny Yar cross-section by 14C date series. Direct accelerator mass spectrometry (AMS) dating of the ice confirmed the relatively young age of ice wedges.


Radiocarbon ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 385-387 ◽  
Author(s):  
David C Lowe ◽  
Gordon W Brailsford ◽  
Gregory W Drummond

A microwave oven is used to pretreat carbonate samples prior to graphitization and radiocarbon dating by accelerator mass spectrometry. The method reduces the risk of contamination of small carbonate samples and provides a fast and convenient method for the acid evolution of CO2.


Radiocarbon ◽  
2013 ◽  
Vol 55 (3) ◽  
pp. 1403-1408
Author(s):  
G Quarta ◽  
S Malgora ◽  
M D'Elia ◽  
V Gaballo ◽  
E Braione ◽  
...  

The ancient Egyptian mummy discovered in the wooden coffin of Ankhpakhered, priest of the god Min, has been studied at CEDAD (Centre for Dating and Diagnostics) at the University of Salento, Italy. The CT scan, performed by the multidisciplinary team of the Mummy Project of Milan, highlighted unusual features of the mummy, suggesting a reuse of the sarcophagus. Furthermore, specimens were taken via endoscopy for accelerator mass spectrometry (AMS) radiocarbon dating and Fourier transform infrared (FTIR) analyses, which have been carried out at CEDAD.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaodan Sun ◽  
Gang Wang ◽  
Qingxu Ma ◽  
Jiahui Liao ◽  
Dong Wang ◽  
...  

Abstract Background Soil organic carbon (SOC) is important for soil quality and fertility in forest ecosystems. Labile SOC fractions are sensitive to environmental changes, which reflect the impact of short-term internal and external management measures on the soil carbon pool. Organic mulching (OM) alters the soil environment and promotes plant growth. However, little is known about the responses of SOC fractions in rhizosphere or bulk soil to OM in urban forests and its correlation with carbon composition in plants. Methods A one-year field experiment with four treatments (OM at 0, 5, 10, and 20 cm thicknesses) was conducted in a 15-year-old Ligustrum lucidum plantation. Changes in the SOC fractions in the rhizosphere and bulk soil; the carbon content in the plant fine roots, leaves, and organic mulch; and several soil physicochemical properties were measured. The relationships between SOC fractions and the measured variables were analysed. Results The OM treatments had no significant effect on the SOC fractions, except for the dissolved organic carbon (DOC). OM promoted the movement of SOC to deeper soil because of the increased carbon content in fine roots of subsoil. There were significant correlations between DOC and microbial biomass carbon and SOC and easily oxidised organic carbon. The OM had a greater effect on organic carbon fractions in the bulk soil than in the rhizosphere. The thinnest (5 cm) mulching layers showed the most rapid carbon decomposition over time. The time after OM had the greatest effect on the SOC fractions, followed by soil layer. Conclusions The frequent addition of small amounts of organic mulch increased SOC accumulation in the present study. OM is a potential management model to enhance soil organic matter storage for maintaining urban forest productivity.


Radiocarbon ◽  
2004 ◽  
Vol 46 (1) ◽  
pp. 455-463 ◽  
Author(s):  
T H Donders ◽  
F Wagner ◽  
K van der Borg ◽  
A F M de Jong ◽  
H Visscher

Sub-fossil sections from a Florida wetland were accelerator mass spectrometry (AMS) dated and the sedimentological conditions were determined. 14C data were calibrated using a combined wiggle-match and 14C bomb-pulse approach. Repeatable results were obtained providing accurate peat chronologies for the last 130 calendar yr. Assessment of the different errors involved led to age models with 3–5 yr precision. This allows direct calibration of paleoenvironmental proxies with meteorological data. The time frame in which 14C dating is commonly applied can possibly be extended to include the 20th century.


Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 933-940 ◽  
Author(s):  
Shinya Yatsuzuka ◽  
Mitsuru Okuno ◽  
Toshio Nakamura ◽  
Katsuhiko Kimura ◽  
Yohei Setoma ◽  
...  

We performed accelerator mass spectrometry (AMS) radiocarbon dating and wiggle-matching of 2 wood samples from charred trunks of trees (samples A and B) collected from an ignimbrite deposit on the northeastern slope of the Baitoushan Volcano on the border of China and North Korea. The obtained calendar years for the eruption are cal AD 945–960 for sample A and cal AD 859–884 and cal AD 935–963 for sample B in the 2-σ range. These results are unable to determine the precise eruption age. The reason for the difference in reported ages may be due to volcanic gas emission prior to the huge eruption.


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