Findings from an in-depth annual tree-ring radiocarbon intercomparison

The radiocarbon (¹⁴C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon intercomparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties

14C Dating and Soil Organic Matter Dynamics in Arctic and Subarctic Ecosystems

The carbon content, pH and 14C concentration of humic acids were determined for three soil series of Arctic and Subarctic ecosystems. The measured 14C ages were interpreted in the light of an equilibrium model of humus formation and of mineralization processes in recent soils, and the coefficient of renovation, Kr, was calculated for humic acids. The comparison of Kr for series formed under different climatic conditions suggested that global warming could accelerate decomposition of soil organic matter and possibly increase productivity of ecosystems of the Arctic region.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Dynamics of Radiocarbon in Soils

We present here a model of humus accumulation in recent soils. We have estimated the coefficients of mineralization of humus and humic acid for a typical Chemozem soil. We suggest a technique for calculating the renewal time of soil with specific activity higher than the modem standard and discuss the results for different soils.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Problems in Radiocarbon Dating of Soils

We discuss our progress in three principal applications of 14C dating of recent and fossil soils: 1) new methods; 2) problems of interpreting 14C soil data (e.g.,14C age of soils, age of soils, duration of humus formation, rate of carbon cycling); and 3) 14C analysis of soil organic matter (OM) in pedology and paleogeography (e.g., soil genesis and evolution, humus formation and OM metamorphosis, geochronology and stratigraphy of Late Pleistocene and Holocene sediments). We suggest exploring the above issues in the analysis of each 14C profile in conjunction with paleogeographical data, and by simulation of the carbon cycle in each type of profile.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Radiocarbon Dating of Medieval Buildings in the Mountainous Part of Ingushetia (Northern Caucasus, Russia)

There are hundreds of preserved medieval buildings in the mountainous part of Ingushetia, including Christian churches, crypts, temples, sanctuaries, battle towers, and living buildings. The chronology of their construction period is still questioned, as there are no radiocarbon (14C) dates published for these buildings and their dating is mainly based on architectural features, a few historical sources, and sometimes on accompanying archaeological material. The aim of this study is to assess more precisely the period of their construction. To do this, we selected the 10 most prominent medieval buildings that contain wooden construction elements and sampled these wooden elements in order to apply 14C accelerator mass-spectrometry dating (AMS) followed by wiggle-matching. From two of these buildings, plaster and mortar were also sampled for 14C AMS dating. This is the first time that these kinds of analyses have been performed for medieval buildings from the mountainous part of Ingushetia. For 6 out of 10 buildings, we acquired sufficiently precise dates that helped us to clarify their construction period. For the other 4 buildings, the acquired dates are still informative but could be refined further with additional 14C analyses. The calibrated dates obtained cover the period from AD 662 until recent time with the majority of them concentrated in 15th-17th centuries. © 2019 by the Arizona Board of Regents on behalf of the University of Arizona

Findings from an in-Depth Annual Tree-Ring Radiocarbon Intercomparison

The radiocarbon (14C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon intercomparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties