bluuebunny/crossref_metadata_2025 huggingface dataset:
Palaeosols within Loess: Dating Palaeoclimatic Events in Kashmir
Authors: Kusumgar Sheela , Agrawal D P , Juyal Navin , Sharma Prabhakar
Published: July 2016

The 14C dates of Kashmir loess-palaeosols form five clusters. The dates, mineral magnetic, stable isotopic, and pollen data help decipher major climatic oscillations as distinct from the minor ones.
Carbon Isotopes in Atmospheric CO2 of the Krakow Region: A Two-Year Record
Authors: Kuc Tadeusz
Published: July 2016

We have been measuring concentration of atmospheric CO2 and its carbon isotope composition in the Kraków region for about two years. Samples are continuously collected at two-week intervals at ca 20m above ground level, close to the center of the industrialized urban area. Sampled atmospheric CO2 is sorbed in a molecular sieve and, after recovery by heating, is converted to benzene. 14C is measured in a liquid scintillation spectrometer, and δ13C of the CO2 is determined in a mass spectrometer. The annual record shows winter-summer variation of 14C, 13C, and CO2 concentration. A long-term trend for 1983 and 1984 indicates a slight decrease of 14C activity (1 22.0 in January 1983; − 1.2% per year), a permanent decrease of δ13CPDB (−9.3‰ in January 1983; −0.3% per year) and an increase of CO2 concentration (344 ppm in January 1983; 1.4ppm per year).
Solar Modulation Effects in Terrestrial Production of Carbon-14
Authors: Castagnoli Giuliana , Lal Devendra
Published: July 2016

This paper is concerned with the expected deviations in the production rate of natural14C on the earth due to changes in solar activity. We review the published estimates of the global production rates of14C due to galactic and solar cosmic ray particles, and present new estimates of the expected secular variations in14C production, taking into account the latest information available on galactic cosmic ray modulation and long-term variations in solar activity.
Variations in Radiocarbon Production in the Earth's Atmosphere
Authors: Korff Serge A , Mendell Rosalind B
Published: July 2016

We have investigated solar phenomena associated with unusual changes in the production rates of 14C in the atmosphere. 14C is produced in interactions of cosmic ray neutrons with nitrogen in the atmosphere. Intensity of the neutrons varies globally and fluctuates with time as a result of interactions of galactic cosmic rays which generate neutrons with plasma and magnetic fields of the solar wind. We estimate the total mean production rate of 14C for solar cycle 20, specifically 1965 to 1975, to be 2.25 ± 0.1 nuclei-cm−2sec−1 from galactic cosmic rays alone, with negligible integrated contribution from solar particle events. Annual averages of Rz, the Zurich sunspot number, and the production rate of 14C, n(14C), were related by n(14C) = 2.60–5.53 × 10–3 Rz ± 3 percent. The contribution of solar flare particles and the zero sunspot limit are discussed with relation to major fluctuations that appear in the radiocarbon versus dendrochronology over short (∼100 years) integration times.
OH Radicals via Atmospheric 14CO
Authors: Volz Andreas , Tönnissen Alfred , Ehhalt D H , Khedim Ahmed
Published: July 2016

Measurements of 14CO in the lower troposphere show a well-defined seasonal variation between 11 ± 1 molecules cm–3 in summer and 25 ± 2 molecules cm–3 in winterat 51°N. The concentration at 27°N in summer is found to be 4.2 ± 0.7 molecules cm–3. From these data and published 12CO measurements, the average concentration of OH radicals in the troposphere is calculated to be 6.5 ± 2.5 × 105 molecules cm–3 using a 2-D time-dependent model. The corresponding 12CO lifetime is two months; the 14CO lifetime is five months.
14C in Extractives from Wood
Authors: Olsson Ingrid U
Published: July 2016

Two Pinus aristata samples submitted by C W Ferguson were separated in different fractions, as was done earlier with Pinus silvestris L from Sweden, to yield different fractions for studies of the pretreatment. One sample in this new series consisted of heartwood and the second of sapwood.

The treatment performed in the radiocarbon laboratory involved an acid treatment by boiling, washings, an hydroxide treatment at 80°C, washings and, finally, another acid treatment before being dried before the combustion. The sodium-hydroxide treatment was repeated to yield at least two soluble and two insoluble fractions.

The treatment performed by the wood chemists involved extractions with ethanol-benzene and water. The remaining wood was dated but was also used for the production of holocellulose. The extractives were partitioned between ethyl ether and water and that from the older wood was used for the isolation of neutrals, acids, and phenols. In all, 19 fractions of these two wood samples were dated.

It is confirmed that a treatment for 30 min in sodium hydroxide at 80°C is not sufficient to remove the extractives from the heartwood or the sapwood. A treatment at 80°C overnight with 1 percent NaOH yielded a sample from the older wood with a 14C content in good agreement with the results predicted from the curve presented by Stuiver (1978). The final statistical uncertainty in the present investigation was ca 4‰. The younger wood yielded results indicating a lower activity than that given by Stuiver.
Regional Sources of Volcanic Carbon Dioxide and Their Influence on 14C Content of Present-Day Plant Material
Authors: Bruns Michael , Levin Ingeborg , Münnich K O , Hubberten H W , Fillipakis S
Published: July 2016

14C measurements were made on present-day plant material with short integration times (tree leaves and sprouts) in the Eifel area, western Germany, where ancient volcanism produces gaseous emanations of considerable yield. Plants growing near sources emanating 14C-free CO2 show a significant depletion in the period of their growth. The same effect is found in the 14C content of recent samples from the Thera (Santorini) Archipelago/Greece. This mixing of “dead” CO2 may lead to pseudo ages in archaeologic or geologic samples of up to 1600 years in samples from the vicinity of CO2 emanating sources.
Conditions Involved in Dating Terrestrial Shells
Authors: Evin Jacques , Marechal Joëlle , Pachiaudi Christiane , Puissegur J J
Published: July 2016

Mollusks living only on ground surface can be expected to give the most reliable results in 14C dating from carbonates of continental origin. One may assume they have a homogeneous biotope and are not affected by any hard-water effect. In order to verify these assumptions and to test shells as routine dating material, results from terrestrial gastropods are compared with other 14C dates from classic biologic material, such as peat, charcoal, or bone, collected in the same archaeologic or geologic levels in miscellaneous places. Two sites were selected for which other chronologic data, such as prehistoric industries or malacologic diagrams were available.

All results indicate older values for 14C shell dates. The discrepancy between “normal” and snail dates amounts to 300 to 1200 14C years and remains the same whatever the absolute age of the sample. All 13C values of perfectly cleaned shells are between —5 to —10%, versus PDB. The initial 14C content of shells that is too low may be different according to species, as suggested by 13C variations.

Although fairly constant, this deviation of 14C ages generally makes such samples unreliable for most archaeologic studies, which often need more precise results. However, some measurements were performed on microfauna shells from several Würmian loess to show that dating of shells may be useful in fairly ancient geologic sediments for lack of better carbonaceous samples. Good agreement of some snail dates with expected sediment ages point to the importance of proper sample selection and pretreatment that might be checked by 13C measurements.
Carbon-14 in the Southern Indian Ocean
Authors: Delibrias Georgette
Published: July 2016

14C measurements were carried out on sea water samples collected in 1973, in the Indian ocean. The results obtained for 9 vertical profiles between 27° S and 48°S are presented. In surface water, the bomb 14C content is maximum at middle latitudes. A time lag relative to the north hemisphere bomb 14C delivery is apparent. In the more southern latitudes, 14C content remains very low.
Progress in Radiocarbon Dating with the Chalk River MP Tandem Accelerator
Authors: Andrews H R , Ball G C , Brown R M , Davies W G , Imahori Yoshio , Milton J C D
Published: July 2016

The evolution of a tandem accelerator 14C dating system at Chalk River is recounted. Background problems and sources of instability are discussed and solutions are described. Details of sample chemistry and source preparation are presented.
Hydrological Implications from 14C Profiling of UK Tufa
Authors: Thorpe P M , Otlet R L , Sweeting M M
Published: July 2016

Tufa is a superficial, secondary deposit of calcium carbonate which accumulates on precipitation from emergent spring waters. It occurs as discrete, localized masses in regions of calcareous country rock.

In the United Kingdom, deposits vary widely in structure and thickness but little is known of the rate of deposition. Some deposits contain laminae assumed to represent annual growth increments and which should contain a 14C and stable isotope record related to the original water from which it was precipitated.

Investigations are reported on tufa from, three areas of different limestones in the United Kingdom (Northwest Yorkshire, South Derbyshire and North Oxfordshire).

Hydrologically, the dating of tufa by 14C involves the same problems as the dating of groundwater. In the case of actively forming tufa, however, it is possible to derive a sequence of measurements, beginning with present day deposition, which clearly demonstrates the applications of age corrections.

At Gordale Scar, Northwest Yorkshire, a profiling study of laminated tufa appears to show bomb trial 14C to a depth of 18mm below the surface, with almost constant values around 50 percent modern (raw data) from 18 to 48mm below the surface. The 14C content of surface tufa lies within the seasonal range of 14C measurements from the parent stream waters.

Results of 50 percent modern in the sequence are consistent with the simplest correction procedures based on δ13C balance and the observed δ13C change on tufa precipitation is a practical demonstration of the fractionation factor ∊13. However, the application of corrections to active, surface tufa and parent waters collected monthly over a period of study (14 months) from all three sites, produce results higher than would be expected from published world 14C levels.
Louvain Natural Radiocarbon Measurements II
Authors: Deumer J. M. , Gilot E. , Capron P. C.
Published: July 2016

The measurements reported in this list were made in the Louvain C14 dating laboratory from July 1962 to October 1963.
Isotopes, Inc. Radiocarbon Measurements IV
Authors: Trautman Milton A.
Published: July 2016

The following list presents dates obtained on a fraction of the total number of measurements made during the years 1962 and 1963 and measurements made previously for which sample data has been recently received. The results which do not appear are withheld pending additional information, or at the request of clients.
Geological Institute Radiocarbon Dates I
Authors: Cherdyntsev V. V. , Alekseyev V. A. , Kind N. V. , Forova V. S. , Sulerzhitskiy L. D.
Published: July 2016

We used the scintillation variant of the radiocarbon method. The scintillator is prepared on the basis of ethylbenzol [benzene], synthesized from acetylene according to the method of Kuchkarev and Kondratenko (1955). For radiocarbon dating we used materials both rich in carbon: wood and charcoal, and [those] poorer: also peat, buried soils, and fossil bones. In the first instance, the initial material for synthesis was [char] coal, which was treated as follows:
Washington State University Natural Radiocarbon Measurements I
Authors: Chatters Roy M.
Published: July 2016

The College of Engineering Research Division radiocarbon dating laboratory began operating in November 1962 employing a Sharp Laboratories, Inc., CDL-14 system based upon the methane method of Fairhall, Shell, and Takashima (1961).

Dates reported herein are calculated using a 5568 yr C14 half-life. The modern standard is taken as 95% of the NBS oxalic acid C14 standard which is converted to CO2 followed by conversion to CH4 in the manner of Fairhall et al. The errors quoted are the 1 σ statistical errors.
ANU Radiocarbon Date List III
Authors: Polach H. A. , Chappell J. , Lovering J. F.
Published: July 2016

The present list comprises only research projects undertaken by the laboratory on the validity of radiocarbon dating of soil, shell, coral and very old samples, all in presence of suspected contamination. All measurements were performed on a Beckman LS-200 liquid scintillation spectrometer (Radiocarbon, 1968, v. 10, p. 179-199). The chemical treatment of samples is given within the text of each section.
Groningen Radiocarbon Dates VIII
Authors: Vogel J. C. , Lerman J. C.
Published: July 2016

This list contains dates for Latin America which have mainly been measured during the past few years. The results are grouped into three categories: geologic, archaeologic, and geophysical, and arranged according to the country of provenance, passing roughly from N to S. Most of the geologic samples are connected with palynologic studies. In cases where the influence of man is apparent in the pollen diagrams, this is explicitly mentioned. Descriptions and comments are based on information provided by the collectors or submitters and on the publications referred to under each sample or series. For the archaeologic section reference has also been made to the general works of Meggers and Evans (1963), Jennings and Norbeck (1964), and Willey (1966).
Fundamentals of Bone Degradation Chemistry: Collagen is Not “The Way”
Authors: Gillespie Richard
Published: July 2016

Collagen-based pretreatment methods for bone yield inconsistent results for those samples where protein preservation is low, as frequently found in bones from the semi-arid zones of Australia and North America. New methods for dealing with low collagen bones are needed, and this paper suggests that the non-collagenous proteins, particularly the blood proteins, may offer advantages for AMS dating because of their better preservation. Amino-acid profiles of collagen and non-collagenous proteins suggest that such differential preservation may be due to physico-chemical differences, and help to explain the poor results from dating low-collagen bones.
Downward Movement of Soil Organic Matter and Its Influence on Trace-Element Transport (210Pb, 137Cs) in the Soil
Authors: Dörr Helmut , Münnich K O
Published: July 2016

Data on depth distribution and 14C content of soil organic carbon, and on soil CO2 production in forest ecosystems are presented and discussed. Downward movement and turnover of soil organic matter is estimated from a box chain model. The downward transfer velocity of soil organic material depends on the litter material composition and on the annual rate of microbial decomposition. Depth distribution of 210Pb and 137Cs was measured. The identical transfer velocity of 210Pb and soil organic material suggests that lead transport is due to movement of the organic material itself. Lead in organic-rich soils obviously is bound rather tightly to the organic carrier by ion exchange or organic complexing. 137Cs migration depends on the turnover and downward movement of soil organic material. Results suggest that cesium is not transported only by the downward movement of solid organic matter, but, due to chemical exchange between the organic and hydrous phases, travels faster than organic matter.
Global Production and Decay of Radiocarbon
Authors: Damon Paul E , Sternberg Robert E
Published: July 2016

The production rate of 14C during the Holocene averaged 2.4 ± 0.2 atoms 14C/cme
2 sec. Neutrons produced by galactic cosmic rays account for 90% of the 14C production with the remaining 10% resulting from neutrons produced by protons from solar flares. Production and decay of 14C can be reconciled by including 14C permanently or temporarily stored in sediments. Sedimentary reservoirs contain ca 30% of all terrestrial 14C. The lagoons, bays, marshes and deltas of the coastal wetlands alone account for 12% of the 14C inventory. The capacity of the coastal wetlands to store carbon has become the subject of renewed interest.
Comparison of the 14C activity of groundwater and recent Tufa from Karst areas in Yugoslavia and Czechoslovakia
Authors: Horvatinčć Nada , Srdoč Dušan , Šilar J A N , Tvrdíková Hana
Published: July 2016

14C activity of dissolved inorganic carbon (DIC) in water and in recent tufa samples in several karst areas of Yugoslavia and Czechoslovakia was measured. Groundwater from 11 karst springs were measured for their isotopic content (14C, 3H, 13C), chemical composition (HCO3
−, Ca2+, Mg2+) and physico-chemical properties (temperature, pH). Seasonal variations of the 14C activity of DIC in two karst springs in Plitvice Lakes area, Yugoslavia, were measured systematically from 1979 – 1987.14C activity of recent tufa samples from several locations downstream were also measured. The activity of DIC in karst spring water in both countries ranged from 63–87 pMC, which is attributed to differences in geologic structure of the recharge area, topsoil thickness and composition. Grouping of 14C activities of DIC ca (82±4)% is evident. Tritium activity at all the springs indicated short mean residence time (1–10 yr). Concentration of HCO3
−, Ca2+ and Mg2+ in spring water varied with geomorphology. 14C activity of streamwater and recent tufa increased downstream from karst springs due to the exchange between atmospheric CO2 and DIC.
AMS and Radiometric Dating of an Etruscan Linen Book and Associated Mummy
Authors: Housley Rupert A , Srdoč Dušan , Horvatinčić Nada
Published: July 2016

An important Etruscan linen “book,” the Liber linteus Zagrabiensis, was preserved in wrappings of an Egyptian mummy. Stylistic estimates for the date of composition of the text vary. Three possible centuries were suggested, the 3rd and the 1st centuries BC and the 1st century ad. Radiometric and AMS dating of the linen book and the mummy has demonstrated multiple uses for differing aged materials. There seem to be at least two sets of linen wrappings of markedly contrasting ages, while separate fractions of the embalming unguent seemed to contain carbon of differing dates. 14C results suggest the most probable age range for the linen book is ca 360–210 cal BC, making the 3rd century BC stylistic date the most likely time of inscription.
Early English Boats
Authors: Switsur Roy
Published: July 2016

A large number of early boats discovered in the waterways of England are presently displayed in museums and as public monuments. In some cases conservation practices have caused problems in the radiocarbon dating of these otherwise undated artifacts. Specimen pretreatments are described and the chronology of the boats in different regions of England are presented with approximate calibration to calendar date ranges.
On a Plausible Physical Mechanism Linking the Maunder Minimum to the Little Ice Age
Authors: Nesme-Ribes Elizabeth , Mangeney Andre
Published: July 2016

To understand better the Earth's climate, we need to know precisely how much radiation the Sun generates. We present here a simple physical mechanism describing the convective processes at the time of low sunspot activity. According to this model, the kinetic energy increased during the Maunder Minimum, causing a decrease of the solar radiation that was sufficient to produce a little Ice Age.
Extended 14C Data Base and Revised CALIB 3.0 14C Age Calibration Program
Authors: Stuiver Minze , Reimer Paula J.
Published: July 2016

The age calibration program, CALIB (Stuiver & Reimer 1986), first made available in 1986 and subsequently modified in 1987 (revision 2.0 and 2.1), has been amended anew. The 1993 program (revision 3.0) incorporates further refinements and a new calibration data set covering nearly 22,000 cal yr (≈18,400 14C yr). The new data, and corrections to the previously used data set, derive from a 6-yr (1986–1992) time-scale calibration effort of several laboratories.
Apparent Ages of Marine Shells: Implications for Archaeological Dating in Hawai'i
Authors: Dye Tom
Published: July 2016

The conventional14C ages of 8 marine shells of known age and 11 marine shells stratigraphically associated with dated wood charcoal show considerable variation from expected ages. One source of this variation is seashore geology; comparison of 6 AMS dates on 3 species of shallow-water, herbivorous gastropod shells from Pleistocene limestone and Holocene volcanic coasts shows that shells from Pleistocene limestone coasts can have apparent, or reservoir,14C ages up to 620 yr greater than shells of the same species from volcanic coasts. The relatively great variation in apparent ages of Hawaiian marine shells poses problems for their use in dating archaeological sites. For best results, an archaeological marine shell should be sourced to a particular local environment, and the apparent age of shells in that environment determined by dating well-provenienced shells of known age.
Radiocarbon Dating Evidence for Mammoths on Wrangel Island, Arctic Ocean, Until 2000 BC
Authors: Vartanyan S. L. , Arslanov Kh. A. , Tertychnaya T. V. , Chernov S. B.
Published: July 2016

Radiocarbon dating results of mammoth tusks, teeth and bones collected on Wrangel Island between 1989 and 1991 reveal a unique mammoth refugium during the Holocene. We used an improved chemical procedure to obtain and purify collagen from bone. Benzene synthesized from the samples was measured using a liquid scintillation counter. The validity of our data has been confirmed by the results of our measurements on two international control sample series (IAEA and TIRI) and by parallel measurements of Wrangel Island mammoth remains at other laboratories.
Radiocarbon Dating of Scrolls and Linen Fragments from the Judean Desert
Authors: Jull A. J. Timothy , Donahue Douglas J. , Broshi Magen , Tov Emanuel
Published: July 2016

We report on new 14C measurements of samples of 18 texts (scrolls) and 2 linen fragments from Qumran Caves 1, 2, and 4 and from Nahal Hever, both in the Dead Sea region. The radiocarbon results are in good agreement with estimates of age based on paleography.
The Younger Dryas Cold Event—Was It Synchronous Over the North Atlantic Region?
Authors: Goślar Tomasz , Arnold Maurice , Pazdur Mieczysław F.
Published: July 2016

Determined independently from annually laminated ice cores and lake sediments, and German pines, the calendar ages of Younger Dryas (YD) boundaries significantly disagree with one another. 14C dates, plotted vs. calendar ages for samples from different sediments, also reveal distinct offsets. The adjustment of varve chronologies to synchronize the boundaries of the YD nearly cancels the discrepancies between 14C data, and supports the synchronism of the YD cold period over the North Atlantic region. However, the exact timing of the event cannot be estimated in this way.
A Radiocarbon Chronology for Prehistoric Agriculture in the Society Islands, French Polynesia
Authors: Lepofsky Dana
Published: July 2016

I discuss a suite of 29 radiocarbon age determinations from four valleys on the islands of Mo'orea and Raiatea in the Society Archipelago. These dates provide the first sequence for the development of prehistoric agricultural production and human-induced environmental change in the Society Islands. Indirect evidence of small-scale agriculture, and by association, human occupation, dates to at least the 7th–10th centuries ad. Agricultural sites themselves date from the early 13th century ad until the late prehistoric/early historic period, with most agricultural activity clustering at the end of the temporal sequence. Valleys with the greatest arable potential were cultivated earlier than less preferred sites. Evidence for extensive landscape transformation in the Opunohu Valley, likely associated with clearing for agricultural purposes, begins soon after the earliest evidence for cultivation and continues throughout prehistory. A larger sample of 14C determinations from strati-graphic excavations in both archaeological sites and “off-site” contexts is required to address many as yet unanswered questions about the prehistoric social and economic development of the Society Islands.
The “Amsterdam Castle”: A Case Study of Wiggle Matching and the Proper Calibration Curve
Authors: van der Plicht J. , Jansma E. , Kars H.
Published: July 2016

We have performed a high-precision 14C wiggle-matching study on two oak beams from the “Castle of Amsterdam”. These beams are also dated by dendrochronology. Our two dating methods can only be made consistent using the recommended calibration curve (1986) instead of the revised one (1993).
Comparison of Fractionation Methods for Soil Organic Matter 14C Analysis
Authors: Trumbore Susan E. , Zheng Shuhui
Published: July 2016

14C measurements provide a useful test for determining the degree to which chemical and physical fractionation of soil organic matter (SOM) are successful in separating labile and refractory organic matter components. Results from AMS measurements of fractionated SOM made as part of several projects are summarized here, together with suggestions for standardization of fractionation procedures. Although no single fractionation method will unequivocally separate SOM into components cycling on annual, decadal and millennial time scales, a combination of physical (density separation or sieving) and chemical separation methods (combined acid and base hydrolysis) provides useful constraints for models of soil carbon dynamics in several soil types.
Performance of the Packard Tri-Carb® 2770TR/SL Liquid Scintillation Analyzer for 14C Dating
Authors: Passo C. J. , Anderson Robert , Roberts David , Cook G. T.
Published: July 2016

We present results that demonstrate the potential of the Packard Tri-Carb® Model 2770TR/SL for radiocarbon dating. For 2 g of sample benzene, a stable background count rate of 0.307 cpm and a stable counting efficiency of 64.78% were determined using a 13–75 keV counting window. Changes to the mathematical routines for t-SIE (quench indicating parameter) calculation and a reduction in the activity of the external standard have enabled stability of the t-SIE to be achieved, and combined with the use of a suitable balance point counting window; all of these factors give the stability of performance required for 14C dating. Calculations based on the above parameters indicate that the limit of detection for 2 g samples, counted for 5000 min, is >48,900 yr bp. The great advantage of this system is that these data were acquired using inexpensive standard 7-mL low potassium borosilicate glass vials. Vial holders manufactured from BGO reduced the background to 0.15 cpm with a minimum effect on efficiency (64.46% for 13–75 keV). A similar calculation of the limit of detection gave >51,700 bp. The use of the BGO vial holders in other instruments employing time-resolved liquid scintillation counting (TR-LSC) (Models 2250CA and 2260XL) also brought about significant improvements in detection limits.
Changes of the CO2 Sources and Sinks in a Polluted Urban Area (Southern Poland) Over the Last Decade, Derived from the Carbon Isotope Composition
Authors: Kuc Tadeusz , Zimnoch Mirosław
Published: July 2016

Time series of δ14C, δ13C, and concentration of atmospheric CO2 covering the last 12 years are available at the Kraków sampling site (southern Poland) representing an urban area exposed to anthropogenic pollution of both local and regional origin. The samples represent continuous monitoring in biweekly intervals. Observations covering the time period 1983–1994 show a linear decrease of the 13C/12C ratio (δ13C = −9.6% in Jan. 1983) with a slope of −0.02% a−1. The decreasing tendency in the case of 14C (δ14C = 221% in January 1983) is weaker with a broad minimum in 1991 (δ14C = 124%) and subsequent gradual increase by ca. 10%, coinciding with a substantial reduction of coal consumption in Poland (26% reduction in 1991–1994 for heat and electricity production), partly compensated in agglomerations by increased gas consumption. The 12-year record of the CO2 concentration in Kraków points to a constant value fluctuating at a high level (average: 373 ppmv) reaching a maximum yearly average of 376 ppmv. These carbon isotope signatures were used for the separation of fossils from biogenic and “background” components, reflecting the strength of relevant sources. The monthly mean of the fossil component varies from ca. 10 ppmv in June to 27.5 ppmv in March while the yearly mean decreased ca. 16 ppmv since 1991.
Probability and Dating
Authors: Ramsey Christopher Bronk
Published: July 2016

Statistical analysis is becoming much more widely used in conjunction with radiocarbon dating. In this paper I discuss the impact of Bayesian analysis (using computer programs such as OxCal) on archaeological research. In addition to simple analysis, the method has implications for the planning of dating projects and the assessment of the reliability of dates in their context.

A new formalism for describing chronological models is introduced here: the Chronological Query Language (CQL), an extension of the model definitions found in the program OxCal.

New methods of Bayesian analysis can be used to overcome some of the inherent biases in the uncertainty estimates of scientific dating methods. Most of these methods, including 14C, uranium series and thermoluminescence (TL), tend to favor some calendar dates over others. 14C calibration overcomes the problem where this is possible, but a Bayesian approach can be used more generally.
High-Precision Radiocarbon Age Calibration for Terrestrial and Marine Samples
Authors: Stuiver Minze , Reimer Paula J. , Braziunas Thomas F.
Published: July 2016

Single-year and decadal radiocarbon tree-ring ages are tabulated and discussed in terms of 14C age calibration. The single-year data form the basis of a detailed 14C age calibration curve for the cal ad 1510–1954 interval (“cal” denotes calibrated). The Seattle decadal data set (back to 11,617 cal BP, with 0 BP = ad 1950) is a component of the integrated decadal INTCAL98 14C age curve (Stuiver et al. 1998). Atmospheric 14C ages can be transformed into 14C ages of the global ocean using a carbon reservoir model. INTCAL98 14C ages, used for these calculations, yield global ocean 14C ages differing slightly from previously published ones (Stuiver and Braziunas 1993b). We include discussions of offsets, error multipliers, regional 14C age differences and marine 14C age response to oceanic and atmospheric forcing.
The Reliability of AMS Radiocarbon Dating of Shells from China
Authors: Zhou Weijian , Head M J , Wang Fubao , Donahue D J , Jull A J T
Published: July 2016

We tested the feasibility of dating freshwater and terrestrial molluscs from the semiarid and arid zone in China, since these types of shell material deposit only aragonite to form their shell structure, and shell integrity can be easily observed using X-ray diffraction. We also tested the possibility of estimating microenvironmental changes from shell δ13C values, but variations within shell populations preclude the use of these values as a reliable indicator. Reservoir ages were calculated for living shells of the same species as fossil shells by using their measured 14C ages, which were recalculated using an average value of atmospheric 14C activity for the years spanning their time of collection as the modern standard. The results indicate that freshwater and terrestrial shells are potentially useful as dating material, provided extreme care is taken in their collection and other datable material (in this case wood and pollen) is within the profile to act as a comparison.
Radiocarbon Age Anomalies in Land Snail Shells from Texas: Ontogenetic, Individual, and Geographic Patterns of Variation
Authors: Goodfriend Glenn A , Ellis G Lain , Toolin L J
Published: July 2016

Accelerator mass spectrometric (AMS) radiocarbon analyses of live-collected, prebomb samples of shell carbonates of the land snails Rabdotus dealbatus and R. alternatus from Texas were carried out to quantify the characteristic age anomalies of land snails from limestone areas. Age anomalies are similar for the two species; they average +700 yr and vary by ±180 yr (1σ) among samples. Serial analysis of 1 shell reveals a significant ontogenetic trend in 14C age anomalies, with older apparent ages (up to 1200 yr) in the apical part of the shell and younger and uniform ages in the last whorl. No trend in age anomalies was found across a broad range of rainfall conditions (from 300 to 1000 mm mean annual rainfall).
AMS 14C Dating of Equipment from the Iceman and of Spruce Logs from the Prehistoric Salt Mines of Hallstatt
Authors: Rom Werner , Golser Robin , Kutschera Walter , Priller Alfred , Steier Peter , Wild Eva M
Published: July 2016

This paper summarizes radiocarbon measurements of mainly botanical samples from the Iceman (“Ötzi”) and from his discovery site, an Alpine glacier at the Austrian-Italian border. The results were obtained by accelerator mass spectrometry (AMS) at 3 different laboratories (Vienna, Austria; Uppsala, Sweden; Gif-sur-Yvette, France) between 1992 and 1997. All the dates, except 2, are consistent with the time period 3360–3100 BC, as previously determined from bone and tissue samples from the Iceman himself. The 2 exceptional dates from wooden artifacts suggest that the site of the Iceman was used as a mountain pass for millennia prior to and after the lifetime of “Ötzi”.

For a 2nd sample complex, we studied logs from the beginning of salt mining in the world's oldest salt mines at Hallstatt in Upper Austria. 14C AMS measurements were performed in Vienna on spruce samples found in the prehistoric mines and from a log-house on the surface. Data evaluation included “wiggle matching” of different sets of tree rings. The results suggest that salt mining in the Hallstatt region took place in the 14th–13th century BC, well before the so-called Hallstatt period.

We discuss in some detail the chemical pretreatment of the samples and the data evaluation. We also present a comprehensive survey of 14C dates available in the literature concerning both botanical remains from the vicinity of the Iceman and from the earliest salt mining in Hallstatt.
Quality Controlled Radiocarbon Dating of Bones and Charcoal from the Early Pre-Pottery Neolithic B (PPNB) of Motza (Israel)
Authors: Yizhaq Meirav , Mintz Genia , Cohen Illit , Khalaily Hamudi , Weiner Steve , Boaretto Elisabetta
Published: July 2016

Radiocarbon dating of early Pre-Pottery Neolithic B (PPNB) deposits at the site of Motza, Israel, was achieved by first prescreening many charcoal and bone samples in order to identify those that are in the most suitable state of preservation for dating. For assessing bone preservation, we determined the collagen contents, and by infrared spectroscopy the collagen purity. The collagen samples of the best preserved bones were then further characterized by their C/N ratios and amino acid compositions. Prescreening of the charcoal samples involved monitoring the changes in infrared and Raman spectra during the acid-alkali-acid treatments. In some samples, we noted that the clay content increased with additional alkali treatments. These samples were rejected, as this could result in erroneous dates. No differences were observed in the 14C dates between charcoal and bone collagen samples. The dates range from 10,600–10,100 cal BP, which is consistent with dates for the early PPNB from other sites. This is of much interest in terms of better understanding where and when domestication of animals began in this period, and how agriculture spread throughout the Levant.
Reconstruction of Past Co2 Concentration at a Natural Co2 Vent Site Using Radiocarbon Dating of Tree Rings
Authors: Marzaioli Fabio , Lubritto Carmine , Battipaglia Giovanna , Passariello Isabella , Rubino Mauro , Rogalla Detlef , Strumia Sandro , Miglietta Franco , D'Onofrio Antonio , Cotrufo M Francesca , Terrasi Filippo
Published: July 2016

Total CO2 exposure levels in a naturally enriched site (Lajatico, Italy) were reconstructed using radiocarbon analysis by accelerator mass spectrometry combined with dendrochronological analysis on wood cores extracted from trees grown in the fossil CO2 source proximity. Over 3 decades (1964–1998), the data show a mean CO2 concentration in the atmosphere of 650 ppm, about twice the current concentration in atmosphere, with a maximum around 1980.
An Assessment of Radiocarbon Dates from Palau, Western Micronesia
Authors: Liston Jolie
Published: July 2016

Archaeological investigations in the Republic of Palau, Micronesia, have produced 409 radiocarbon age determinations from cultural contexts, indicating a range of Palauan occupation from about 3000 yr ago into the modern era. However, these dates are scattered among numerous sources (many difficult to obtain) and are presented in a number of different formats and calibrations. The goal of this paper is to compile a usable, systematic database of all of these Palauan cultural 14C assays. This database will be suitable for developing and evaluating chronological models, an effort being undertaken as a separate paper. Prior to constructing prehistoric colonization and cultural chronologies for Palau, the validity of each assay and the relative adequacy in sample size per cultural and environmental zones must be examined. After systematic recalibration, the reliability of the dates is evaluated in light of sample material, cultural context, and site formation processes. A method for dating monumental earthwork complexes through site formation analysis is presented. Sets of 237 valid and 58 potentially valid 14C dates remain to develop chronological models. The representation of Palau's environmental zones, site types, and regions within the dating pool is examined and compared to ensure meaningfulness in these chronological models. Newly obtained 14C age determinations are also provided.
University of Lund Radiocarbon Dates I
Authors: Håkansson Soren
Published: July 2016

Plans for a radiocarbon dating laboratory at the University of Lund were initiated by Tage Nilsson and Holger Arbman in 1962. Work was begun in 1964 and at the end of 1965 most of the dating equipment was installed. Dating began in 1966 after careful testing of counting electronics and counters.

The dating system has two 1-L copper-walled proportional counters of Östlund-Engstrand construction (for details see Stockholm V. p. 204, Fig. 1) surrounded by 2.5 cm of selected lead, followed by a ring of 23 cosmic-ray Geiger counters (model HZ-100, Zentralwerkstatt Göttingen). On all sides are at least 20 cm of iron. Above and on both long sides of the counters are 10 cm of paraffin wax with about 12% boric acid between the iron layers.
13C Variation in Limestone On An Aquifer-Wide Scale and Its Effects On Groundwater 14C Dating Models
Authors: Muller A B , Mayo A L
Published: July 2016

In modeling the initial 14C activity of ground waters, the δ13C of marine limestone is taken conventionally to vary little about 0‰ PDB. This variation was found to be 6.28‰ in samples taken over intervals from 10-2 to 105m in the Mooney Falls Member of the Redwall Limestone in northern Arizona. Such a variation will cause appreciable variability in the results of all four initial activity models tested. The variability, due primarily to a numerical instability in the models dependent on this parameter, can introduce significant uncertainty into groundwater “age” calculations.
Radiocarbon Accelerator (AMS) Dates for the Epipaleolithic Settlement At Abu Hureyra, Syria
Authors: Moore A M T , Gowlett J A J , Hedges R E M , Hillman G C , Legge A J , Rowley-Conwy P A
Published: July 2016

The prehistoric settlement of Abu Hureyra in Syria was occupied in both the Epipaleolithic and Neolithic periods. It has provided significant evidence for changes in economy at the time of the inception of agriculture in southwest Asia. Twenty accelerator mass spectrometry (AMS) dates have been obtained to determine the duration of occupation of the Epipaleolithic settlement there and the precise age of samples of cereal grains and animal bones found within it. The results have demonstrated that the AMS technique can answer such questions because it dates exceedingly small samples with high precision. The dates indicate that the Epipaleolithic settlement was inhabited for about a millennium, from before 11,000 to nearly 10,000 bp, significantly longer than had been anticipated from study of the artifacts.
Lamont Radiocarbon Measurements VIII
Authors: Broecker Wallace S. , Olson Edwin A.
Published: July 2016

Like Lamont VI (Broecker and Olson, 1959), this list contains only results on samples of known age (most of which formed during the past ten years). The measurements were made largely in order to gain an understanding of the distribution of radiocarbon within the dynamic carbon reservoir. Again, the data are not reported primarily with the idea of drawing new conclusions but rather to bring together in one place information which is presently scattered throughout the literature or which otherwise might remain unpublished.
Transect Along 24°n Latitude of 14C in Dissolved Inorganic Carbon in the Subtropical North Atlantic Ocean
Authors: Severinghaus Jeffrey P. , Broecker Wallace S. , Peng Tsung-Hung , Bonani Georges
Published: July 2016

The distribution of bomb-produced 14C in the ocean provides a powerful constraint for circulation models of upper ocean mixing. We report 14C measurements from an east-west section of the main thermocline at 24°N latitude in the subtropical North Atlantic Ocean in summer 1992, and one profile from the Gulf of Mexico in 1993. Observed gradients reflect the transient invasion of bomb 14C into the thermocline via mixing along isopycnals from the poleward outcrop, with progressively more sluggish mixing at greater depths. A slight deepening of the profile is observed over the 20-yr period since the GEOSECS survey at one location where the comparison is possible.
Radiocarbon Dating Tephra Layers in Britain and Iceland
Authors: Dugmore A. J. , Cook G. T. , Shore J. S. , Newton A. J. , Edwards K. J. , Larsen GuÐrún
Published: July 2016

Layers of volcanic ash, or tephra form widespread chronostratigraphic marker horizons which are important because of their distinctive characteristics and rapid deposition over large areas. Absolute dating of prehistoric layers effectively depends upon14C analysis. We focus here on Icelandic tephra layers at both proximal and distal sites and consider three strategies to obtain age estimates: 1) the conventional dating of individual profiles; 2) high-precision multisample techniques or “wiggle-matching” using stratigraphic sequences of peat; and 3) a combination of routine analyses from multiple sites. The first approach is illustrated by the dating of a peat profile in Scotland containing tephra from the ad 1510 eruption of Hekla. This produced a14C age compatible with ad 1510, independently derived by geochemical correlation with historically dated Icelandic deposits. In addition, theca.2100 bp date for the Glen Garry tephra in Scotland, determined by a series of dates on a peat profile in Caithness, is supported by its stratigraphic position within14C dated profiles in Sutherland, and may be applied over a very large area of Scotland. More precise dates for individual tephras may be produced by “wiggle-matching”, although this approach could be biased by changes in peat-bog stratigraphy close to the position of the tephra fall. As appropriate sites for “wiggle-match” exercises may be found only for a few Icelandic tephras, we also consider the results of a spatial approach to14C dating tephra layers. We combined dates on peat underlying the same layer at several sites to estimate the age of the tephra: 3826 ± 12 bp for the Hekla-4 tephra and 2879 ± 34 bp for the Hekla-3 tephra. This approach is effective in terms of cost, the need for widespread applicability to Icelandic tephra stratigraphy and the production of ages of a useful resolution. We stress the need for accurate identification of tephra deposits without which the conclusions drawn from subsequent14C dating will be fundamentally flawed.
Ecological Chronology of Nuclear Fuel Cycle Sites
Authors: Buzinny Michael , Kovalyukh Nikolaj , Likhtarjov Ilja , Los Ivan , Nesvetajlo Valerij , Pazdur Mieczysław F. , Skripkin Vadim , Shkvorets Oleg , Sobotovich Emlen
Published: July 2016

We compared 14C levels in annual growth rings of pine trees around the Tomsk nuclear fuel reprocessing plant (NFRP) and the Chernobyl nuclear power plant (NPP). At the Chernobyl site, samples were taken from the control area (within a 30-km radius zone around the site) to a distance of 80 km. In Tomsk, we collected samples between 8–10 km and 10–15 km from the site, taking into account prevailing wind directions. Background samples were collected 200 km from the plant. Samples were converted to benzene and counted in an ultra-low-level LSC Quantulus 1220™. Because of the Chernobyl accident, a signal can be detected in the background of routine plant operation. Comparison with the Tomsk data suggests that the routine discharges from Tomsk are more significant than the discharge from the Chernobyl accident. We estimated Tomsk NFRP annual discharge level at up to 30–45 TBq 14C from 1985 to 1988.
Radiocarbon Dispersion around Canadian Nuclear Facilities
Authors: Milton G. M. , Kramer S. J. , Brown R. M. , Repta C. J. W. , King K. J. , Rao R. R.
Published: July 2016

Canadian deuterium uranium (CANDU) pressurized heavy-water reactors produce 14C by neutron activation of trace quantities of nitrogen in annular gas and reactor components (14N(n,p)14C), and from 17O in the heavy water moderator by (17O(n,α)14C). The radiocarbon produced in the moderator is removed on ion exchange resins incorporated in the water purification systems; however, a much smaller gaseous portion is vented from reactor stacks at activity levels considerably below 1% of permissible derived emission limits. Early measurements of the carbon speciation indicated that >90% of the 14C emitted was in the form of CO2. We conducted surveys of the atmospheric dispersion of 14CO2 at the Chalk River Laboratories and at the Pickering Nuclear Generating Station. We analyzed air, vegetation, soils and tree rings to add to the historical record of 14C emissions at these sites, and to gain an understanding of the relative importance of the various carbon pools that act as sources/sinks within the total 14C budget. Better model parameters than those currently available for calculating the dose to the critical group can be obtained in this manner. Global dose estimates may require the development of techniques for estimating emissions occurring outside the growing season.
Use of Bomb-Produced 14C to Evaluate the Amount of CO2 Emanating from Two Peat Bogs in Finland
Authors: Jungner Högne , Sonninen Eloni , Possnert Göran , Tolonen Kimmo
Published: July 2016

We used moss increment counting to obtain well-defined samples of the topmost peat layers of two Sphagnum fuscum hummocks. The two ombrotrophic bogs, Lakkasuo in central Finland and Korvinsuo in eastern Finland, are of different ages, covering 3 and 9 ka, respectively. Using AMS dating, we traced bomb-produced 14C through the topmost parts of the two peat profiles. A well-defined 14C activity peak was found in both sequences dating the corresponding layer to ad 1965. A comparison between the maximum peat activities and the corresponding atmospheric values for the period of interest provides an opportunity to evaluate the amount of CO2 emanating from the decaying peat bog, and taken up by the living sphagnum plants.

Considerable variations in δ13C values were also observed. These variations indicate, at least partly, annual variations in the emission rate of CO2 from decomposition of older peat in the bog, and are connected with climatic factors such as temperature and precipitation.