bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal Changes of the14C Reservoir Effect in Lakes
Authors: Geyh Mebus A. , Schotterer U. , Grosjean M.
Published: July 2016

Conventional radiocarbon dates for sediment samples from aquatic systems and of coeval terrestrial samples deviate from each other due to the reservoir effect. The reservoir correction is usually assumed to be constant with time for a specific aquatic system. Our studies confirm that seasonal and secular changes are frequent and are governed by the limnological conditions. Lakes have two principal sources of14C: atmospheric CO2and the total dissolved inorganic carbon (TDIC) of the entering groundwater and runoff. The former has values ofca.100 pMC; the latter usually has a14C value well below 100 pMC. Atmospheric CO2enters the lake by exchangeviaits surface. The proportions of these two kinds of input determine the magnitude of the reservoir correction in freshwater lakes. It is mainly a function of the volume/surface ratio of the lake and, consequently a function of the water depth. The surface of lakes with outflow does not change when sedimentation decreases the depth of the water. The depth of Schleinsee Lake in southern Germany has decreased from 30 to 15 m sinceca.9000 bp. As a result, the reservoir correction has decreased fromca.-1550 to -580 yr. In contrast, the depth of Lake Proscansko in Croatia increased with growth of the travertine dam and the reservoir correction changed fromca.-1790 to -2650 yr during the last 8800 yr. The largest fluctuations of lake levels occur in closed lakes in arid regions when the climate changes from humid to arid andvice versa.As a result, the reservoir correction of the14C dates for the total organic fraction from Lejía Lake in the Atacama Desert of Chile varied between <-1800 yr and -4700 yr over a period of only 1800 yr between 11,500 and 9700 bp. The corresponding reservoir correction for the marl fraction is much higher. In summary, accurate and reliable14C dating of lake sediments requires a study of the temporal changes of the reservoir effect by analysis of both the organic and marl fractions. The most reliable14C dates are obtained from terrestrial plant remains.
Apparent 14C Ages of Marine Mollusk Shells from a Greek Island: Calculation of the Marine Reservoir Effect in the Aegean Sea
Authors: Facorellis Yorgos , Maniatis Yannis , Kromer Bernd
Published: July 2016

The excavation of the Cyclope cave, situated on the deserted island of Youra in the Northern Sporades (39°22'N, 24°10'E), revealed material of marine and terrestrial origin in undisturbed layers, suitable for radiocarbon dating. In some cases, material from different reservoirs was found together in the same archaeological layer. This research had two aims. The first was the dating of charcoal-seashell pairs in order to determine the marine reservoir effect in this region, based on samples with ages spanning from the end of the 8th millennium to the beginning of the 7th millennium bc. The second aim was dating the stratigraphy of this site, by using the calculated δR value in conjunction with the marine calibration curve. This enabled the accurate calibration of the 14C ages of marine samples found in layers without charcoal pieces. The results show that this is the oldest human settlement ever found on an island in the Aegean Sea.
Molecular, Radioactive and Stable Carbon Isotope Characterization of Estuarine Particulate Organic Matter
Authors: Megens Luc , Van Der Plicht Johannes , De Leeuw Jan W.
Published: July 2016

Organic matter in sediments and suspended matter is a complex mixture of constituents with different histories, sources and stabilities. To study these components in a suspended matter sample from the Ems-Dollard Estuary, we used combined molecular analysis with pyrolysis/gas chromatography/mass spectrometry and stable and radioactive carbon isotope analyses of the bulk and separated chemical fractions. Carbohydrates and proteins, ca. 50% of the total organic carbon (TOC), are much younger than the bulk sample and have a somewhat higher δ13C value. Lipids and the final residue are considerably older and have lower δ13C values. The final residue, ca. 17% of the total carbon, consists mainly of aliphatic macromolecules that could be derived from algae or terrestrial plants. The δ13C value points to a marine origin.
The 14C Age of Humic Substances in Paleosols
Authors: Alexandrovskiy Alexander L. , Chichagova Olga A.
Published: July 2016

By comparing the radiocarbon age of the soils under burial mounds of known archaeological age with the surface-exposed (background) soils of the surrounding landscapes, we may evaluate the rates of humus renewal in these soils. In the cold climate of the mideastern areas of the Russian plains, the value of humus rejuvenation coefficient decreases. This shows that humus renewal is 5–10 times slower than in the warmer climate of the southern regions. Using the obtained data on the rejuvenation rate of humus substances, we can determine the age of paleosols and study the dynamics of the carbon exchange processes in the biosphere.
Using 14C as a Tracer of Carbon Accumulation and Turnover in Soils
Authors: Milton G. M. , Kramer S. J.
Published: July 2016

Three very different Canadian soils—clay soils of the St. Lawrence Lowlands, sandy forest soils of the Ottawa Valley, and organic-rich sediments from a wetland on the Canadian Shield—have been cored, sliced and separated into different density fractions, and the radiocarbon content of these soil fractions measured. In two of the areas sampled, cores were obtained close to operating nuclear reactors, as well as from beyond their region of influence. As a consequence, it has been possible to ascertain the depths of penetration of both the weapons-testing pulse (peaking in 1963), and a 25–50-yr chronic reactor input of 14C.

The percentage of carbon stored in different density fractions varied with soil type. Turnover times for bulk soil organic carbon, estimated from soil degassing rates, have been compared with those predicated on the residual “bomb” 14C in background cores, and/or on the ratio of reactor-emitted 14C retained in the soils to the total deposited during the lifetime of operation. Residence times for the heavy carbon fraction present at depths below the influence of anthropogenic inputs have also been estimated.

The accumulated data will be incorporated in a revised soil model, adjusted for the parameters deemed to be most important to carbon turnover rates under Canadian conditions.
Report of the Business Meeting, Friday 20 June 1997
Authors: Van Der Plicht Johannes , Mook Willem G.
Published: July 2016

The last scientific presentation at the conference was a special paper by Minze Stuiver, reviewing all radiocarbon calibration data available to date.
Radiocarbon Calibration by Means of Mass Spectrometric 230Th/234U and 14C Ages of Corals: An Updated Database Including Samples from Barbados, Mururoa and Tahiti
Authors: Bard Edouard , Arnold Maurice , Hamelin Bruno , Tisnerat-Laborde Nadine , Cabioch Guy
Published: July 2016

As first shown by Bard et al. (1990a), high-precision 230Th-234U ages can be used successfully to calibrate the radiocarbon time scale beyond the high-precision tree-ring calibration that now reaches 11,900 cal bp (Kromer and Spurk 1998). Using mass spectrometric techniques, we measured 14C and 230Th ages on new samples collected from boreholes drilled off the islands of Tahiti and Mururoa (French Polynesia) in order to complement the database previously obtained on Barbados corals (Bard et al. 1990a, 1993).
Revisions and Extension of the Hohenheim Oak and Pine Chronologies: New Evidence About the Timing of the Younger Dryas/Preboreal Transition
Authors: Spurk Marco , Friedrich Michael , Hofmann Jutta , Remmele Sabine , Frenzel Burkhard , Leuschner Hanns Hubert , Kromer Bernd
Published: July 2016

Oak and pine samples housed at the Institute of Botany, University of Hohenheim, are the backbone of the early Holocene part of the radiocarbon calibration curve, published in 1993 (Becker 1993; Kromer and Becker 1993; Stuiver and Becker 1993; Vogelet al.1993). Since then the chronologies have been revised. The revisions include 1) the discovery of 41 missing years in the oak chronology and 2) a shift of 54 yr for the oldest part back into the past. The oak chronology was also extended with new samples as far back as 10,429 BP (8480 BC). In addition, the formerly tentatively dated pine chronology (Becker 1993) has been rebuilt and shifted to an earlier date. It is now positioned by14C matching at 11,871-9900 BP (9922–7951 BC) with an uncertainty of ±20 yr (Kromer and Spurk 1998). With these new chronologies the14C calibration curve can now be corrected, eliminating the discrepancy in the dating of the Younger Dryas/Preboreal transition between the proxy data of the GRIP and GISP ice cores (Johnsenet al.1992; Tayloret al.1993), the varve chronology of Lake Gościąż (Goslaret al.1995) and the pine chronology (Becker, Kromer and Trimborn 1991).
The Maunder Minimum: An Interlaboratory Comparison of Δ14C from AD 1688 to AD 1710
Authors: Damon Paul E , Eastoe Christopher J , Mikheeva Irina B
Published: July 2016

Measurements on same-age tree-ring samples from proximal Ural Mountain trees by the Ioffe Institute research group and at the University of Arizona demonstrate a variance corresponding to a standard deviation of ±5.1% for Ioffe compared to ±2.1% for Tucson. There is also a calibration difference of 4.3 ±1.2 ‰. Comparison of the same years measured in Seattle on wood from the Pacific Northwest shows an offset of 2.2 ± 0.5 ‰. This is not a calibration error, but rather is expected from the well-documented evidence for divergence and upwelling of 14C-depleted CO2 along the west coast of North America.
Reliability of Bone Gelatin AMS Dating: Rattus Exulans and Marine Shell Radiocarbon Dates from Pauatahanui Midden Sites in Wellington, New Zealand
Authors: Athfield Nancy Beavan , McFadgen Bruce , Sparks Rodger
Published: July 2016

A suite of 6 bone gelatin accelerator mass spectrometry (AMS) radiocarbon dates for Rattus exulans Peale and associated beta decay 14C dates for Austrovenus stutchburyi shell are presented for 4 middens at Pauatahanui, Wellington, New Zealand. Mean calibrated age ranges of Rattus exulans (520–435 BP and 350–330 BP at 95% confidence level) and shell (465–375 BP at 95% confidence level) from the 4 midden sites overlap. The agreement between Rattus exulans bone gelatin dates and associated shell provides an inter-sample comparison of 14C dating using both gas counting (beta decay) and AMS dating techniques. We examine the adequacy of the standard gelatinization treatment for bone samples, which has been employed consistently at the laboratory since 1995.
Changes in 14C Activity Over Time During Vacuum Distillation of Carbon from Rock Pore Water
Authors: Davidson G R , Yang I C
Published: July 2016

The radiocarbon activity of carbon collected by vacuum distillation from a single partially saturated tuff began to decline after approximately 60% of the water and carbon had been extracted. Disproportionate changes in 14C activity and δ13C during distillation rule out simple isotopic fractionation as a causative explanation. Additional phenomena such as matrix diffusion and ion exclusion in micropores may play a role in altering the isotopic value of extracted carbon, but neither can fully account for the observed changes. The most plausible explanation is that distillation recovers carbon from an adsorbed phase that is depleted in 14C relative to DIC in the bulk pore water.
Change of Diet of the Greenland Vikings Determined from Stable Carbon Isotope Analysis and 14C Dating of Their Bones
Authors: Arneborg Jette , Heinemeier Jan , Lynnerup Niels , Nielsen Henrik L , Rud Niels , Sveinbjörnsdóttir Árný E
Published: July 2016

Bone samples from the Greenland Viking colony provide us with a unique opportunity to test and use 14C dating of remains of humans who depended upon food of mixed marine and terrestrial origin. We investigated the skeletons of 27 Greenland Norse people excavated from churchyard burials from the late 10th to the middle 15th century. The stable carbon isotopic composition (δ13C) of the bone collagen reveals that the diet of the Greenland Norse changed dramatically from predominantly terrestrial food at the time of Eric the Red around AD 1000 to predominantly marine food toward the end of the settlement period around AD 1450. We find that it is possible to 14C-date these bones of mixed marine and terrestrial origin precisely when proper correction for the marine reservoir effect (the 14C age difference between terrestrial and marine organisms) is taken into account. From the dietary information obtained via the δ13C values of the bones We have calculated individual reservoir age corrections for the measured 14C ages of each skeleton. The reservoir age corrections were calibrated by comparing the 14C dates of 3 highly marine skeletons with the 14C dates of their terrestrial grave clothes. The calibrated ages of all 27 skeletons from different parts of the Norse settlement obtained by this method are found to be consistent with available historical and archaeological chronology. The evidence for a change in subsistence from terrestrial to marine food is an important clue to the old puzzle of the disappearance of the Greenland Norse, obtained here for the first time by measurements on the remains of the people themselves instead of by more indirect methods like kitchen-midden analysis.
Simultaneously Measuring 14C and Radon in Benzene Dating Samples
Authors: Theodórsson Pall
Published: July 2016

After benzene synthesis, radiocarbon dating samples are usually stored for 3–4 weeks before counting to allow an eventual radon contamination to decay to a negligible level. This paper presents a technique that can minimize, and often eliminate, this delay by using a simple single-phototube liquid scintillation counting system, specifically designed for 14C dating. Radon contamination is assessed by pulses of 214Po (a 222Rn decay product, half-life 0.16 μs), identified through pulse-time analysis. For each 214Po pulse, 0.49 beta particle pulses of 214Pb and 214Bi fall in the 14C counting window, and the 214Po pulses are used to correct the 14C count rate. A 14C sample (count rate 11.6 cpm) was measured continuously for 16 days. It was then doped with radon, which increased the first 24-hr count rate in the 14C channel by 3.8 cpm, and the sample was measured for 27 more days. Radon did not measurably affect the 14C-corrected count rate. Counting a sample for 2 min reveals whether it needs storing. If the radon concentration is low, the sample can be measured immediately without degrading accuracy.
A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA
Authors: Kennedy Michael A , Russell Ann D , Guilderson Tom P
Published: July 2016

We present a Holocene radiocarbon chronology of hunter-gatherer occupation based on contemporaneous samples of charcoal and Mytilus californianus shell recovered from 7 archaeological sites near Bodega Bay, California, USA. A series of 127 14C ages reveals a chronological sequence that spans from 8940–110 cal BP (1 σ). This sequence serves as a foundation for the interpretation of behavioral change along the northern California coast over the last 9000 yr, including the adaptive strategies used by human foragers to colonize and inhabit coastal areas of this region. These 14C ages will also permit us to explore major dimensions of temporal change in Holocene ocean conditions (via marine reservoir corrections) and their potential effect on the resources available to ancient hunter-gatherers.
Chemical Isotope Dilution for 14C Ams and the Potential for GC/AMS
Authors: Gillespie Richard
Published: July 2016

The advent of accelerator-based mass spectrometry (AMS) radiocarbon dating has reduced the minimum sample size required to ca 1 mg from the 1 g of traditional beta counting techniques (cf Wölfli, Polach & Andersen, 1984). However, it is clear that even smaller samples will be necessary for some fields of endeavor, particularly environmental work where the absolute quantities are small, perhaps of the order of a few micrograms (Currie et al, 1985). This raises serious problems in the handling and measurement of such small amounts, so that dilution will sometimes be required. Normally, sample dilution is accomplished by adding “dead” CO2 to the combusted sample CO2, which requires very careful measurement of two gas pressures for the calculation of a dilution ratio. By forming a chemical derivative of a sample before combustion, gas pressure measurement is not necessary and an exact dilution ratio can be selected by judicous choice of the dilution reagent. This paper demonstrates that such a technique is possible for the AMS 14C dating of derivatized amino acids.
Lódź Radiocarbon Dates II
Authors: Kanwiszer Andrzej , Trzeciak Paweł
Published: July 2016

The following list consists of dates of archaeologic and geologic samples measured from January 1981 to December 1982. Measurements were continued with the same proportional counter system, pretreatment procedure, methane preparation, measurement, and calculation, as described previously (Kanwiszer & Trzeciak, 1984). Ages were computed on the 14C half-life of 5568 ± 30 years. Precision is reported as one standard deviation based only on statistical counting uncertainties in the measurement of the background, NBS modern standard, and sample activities. The dates are not corrected for 13C fractionation. Descriptions and comments are based on information supplied by submitters of samples.
University of Pennsylvania Radiocarbon Dates III
Authors: Ralph Elizabeth K.
Published: July 2016

The radiocarbon laboratory at the University of Pennsylvania is sponsored jointly by the University Museum and the Physics Department. In this laboratory our primary function is to date archaeologic samples from those four regions of the world in which the University Museum studies are concentrated, namely, the Near East, South America, Central America, and the Arctic. Dates for sites in the first two regions are included in this list, and a long series of temple lintels from Tikal, Guatamala is now being processed. Dates for the Arctic were obtained intermittently from 1953 through 1955 (with solid-carbon counting); others, more recently. The materials for many of the Arctic dates, however, were not reliable; that is, they were physically contaminated before processing in the laboratory. We hope that better samples can be found for future Arctic dating. Our Arctic dates which now furnish tentative age ranges for Punuk, Birnirk, Kachemak Bay III, Okvik, Old Bering Sea, Ipiutak, Norton, Dorset, Kachemak Bay I, Choris, Firth River (Early Mountain Phase), Sarqaq, and Denbigh Flint Complex Periods have been submitted to American Antiquity (Rainey and Ralph, in press) along with detailed discussions of possible contaminations.
Bern Radiocarbon Dates I
Authors: Oeschger H. , Schwarz U. , Gfeller Chr.
Published: July 2016

This list covers the measurements made at the University of Bern up until summer 1958. The low-level apparatus is described by Houtermans and Oeschger (1958).
Mass-Spectrometer Analyses of Radiocarbon Standards
Authors: Craig Harmon
Published: July 2016

Twenty-four samples of CO2 from combustion of the NBS oxalic-acid radiocarbon standard, submitted from 13 radiocarbon laboratories, were analyzed for C13 content in this laboratory in order to provide comparative data for normalizing the counting results. The samples were analyzed on Samson, a 60° sector, six-inch radius, McKinney-Nier type mass-spectrometer with magnetic switching between sample and standard gas feed to the instrument.
Lamont Natural Radiocarbon Measurements VII
Authors: Olson Edwin A. , Broecker Wallace S.
Published: July 2016

Radiocarbon-age measurements reported here were made at Lamont Geological Observatory between July 1958 and November 1960. Sample descriptions are classified as follows:

I.

Samples associated with glacial deposits

II.

Samples associated with marine coastal deposits

III.

Samples associated with marine coastal deposits uplifted by glacial rebound

IV.

Samples associated with pluvial-lake deposits

V.

Samples from deep-sea cores

VI.

Samples from cave deposits

VII.

Miscellaneous samples of geologic interest

VIII.

Samples of archaeologic interest
WOCE AMS Radiocarbon I: Pacific Ocean Results (P6, P16 and P17)
Authors: Key Robert M. , Quay Paul D. , Jones Glenn A. , McNichol A. P. , Von Reden K. F. , Schneider Robert J.
Published: July 2016

AMS radiocarbon results from the World Ocean Circulation Experiment in the Pacific Ocean show dramatic changes in the inventory and distribution of bomb-produced 14C since the time of the GEOSECS survey (8/73–6/74). Near-surface Δ14C values for the eastern portion of both the northern and southern subtropical gyres decreased by 25–50‰, with the change being greater in the north. Equatorial near-surface values have increased by ca. 25‰. Changes in the 250–750-m depth range are dramatically different between the northern and southern basins. The intermediate and mode waters of the southern basin have increased by as much as 75‰ since GEOSECS. Waters of similar density in the northern hemisphere are not exposed to the Southern Ocean circulation regime and are significantly less ventilated, showing maximum changes of ca. 50‰.
Regional Radiocarbon Effect Due to Thawing of Frozen Earth
Authors: Damon P. E. , Burr George , Peristykh A. N. , Jacoby G. C. , D'Arrigo R. D.
Published: July 2016

Accelerator mass spectrometry (AMS) measurement of 25 single-year tree rings from AD 1861–1885 at ca. ±3.5‰ precision shows no evidence of an anomalous 11-yr cycle of 14C near the Arctic Circle in the Mackenzie River area. However, the Δ14C measurements are lower on average by 2.7 ± 0.9 (ō)‰ relative to 14C measurements on tree rings from the Pacific Northwest (Stuiver and Braziunas 1993). We attribute this depression of Δ14C to thawing of the ice and snow cover followed by melting of frozen earth that releases trapped 14C-depleted CO2 to the atmosphere during the short growing season from May through August. Correlation of Δ14C with May–August estimated temperatures yields a correlation index of r = 0.60. The reduction in Δ14C is dominated by seven years of anomalous depletion. These years are 1861, 1867–1869, 1879–1880 and 1883. The years 1867–1869 are coincident with a very strong ENSO event.
Report: Summary of the Workshop “Aspects of High-Precision Radiocarbon Calibration”
Authors: Kromer Bernd , Ambers Janet , Baillie M. G. L. , Damon Paul E. , Hesshaimer Vago , Hofmann Jutta , Jöris OLAF , Levin Ingeborg , Manning S. W. , McCormac F. G. , Van Der Plicht Johannes , Spurk Marco , Stuiver Minze , Weninger Bernhard
Published: July 2016

Recently, in an intercomparison of the Hohenheim German oak chronology (Becker 1993) and the Göttingen chronology (Leuschner and Delorme 1988), an error was discovered in the former (Leuschner, in preparation). Due to an error in adding sections at 5241 bc, 41 yr are missing in the published Hohenheim chronology. After correction of the error, the two chronologies synchronize over their entire common length, back to 7200 bc.
Radiocarbon and Thermoluminescence Studies of the Karst Pipe Systems in Southwest England and South Wales
Authors: Pazdur Mieczysław F. , Bluszcz Andrzej , Pazdur Anna , Morawiecka Iwona
Published: July 2016

Paleokarst forms in raised beach deposits of Southwest England and South Wales and generally known as “pipes” were dated by 14C and thermoluminescence (TL) methods. Current geological opinion is that these pipes are features that developed under the cover of periglacial-solifluctional deposits due to periglacial conditions prevalent in the Late Devensian. In the present study, TL was used to determine the age of quartz grains forming the raised beaches. 14C ages were obtained from carbonate cements within sandrock and on the pipe walls. TL ages measured for quartz grains separated from sandrock samples are older than 80 ka bp, whereas the corresponding TL dates obtained from the sandy material of pipe infills center around 40 ka bp. All carbonates yielded finite apparent 14C dates that range from ca. 45 ka bp to 27 ka bp for sandrock. The apparent 14C dates obtained on carbonate cements from the pipe walls fall into two groups, one ranging from 30 ka bp to 22 ka bp and the other from 15 ka bp to 7 ka bp. On the basis of geochemical considerations, we conclude that the sandrock cements formed between 35 and 25 ka bp and pipe walls cemented between 30 and 2 ka bp with a break during the climate deterioration caused by last ice sheet advance.
Radiocarbon Dating of Shells and Foraminifera from the Skagen Core, Denmark: Evidence of Reworking
Authors: Heier-Nielsen Susanne , Conradsen Keld , Heinemeier Jan , Knudsen K. L. , Nielsen H. L. , Rud Niels , Sveinbjörnsdóttir Á. E.
Published: July 2016

We report on 69 radiocarbon dates of mollusk shells and benthic foraminifera from the upper 132 m of the marine shelf sediments of the Skagen Core (220 m total length). The dated sequence covers the Late Glacial and the Holocene (from 15 ka bp to Recent). Sedimentation rates range from 1 to 70 m ka−1. The macrofossil shell dates follow a smooth curve constituting an age model for dating the sediments. The foraminiferal dates fall into two groups: those that agree exactly with the mollusk shells and those that deviate substantially, always being older than the shells by as much as 5 ka. One mixed foraminiferal sample consisted of members from both groups, and as a result, the age deviation of the sample turned out to be some weighted average. The data indicate that the age deviations are due to admixtures of reworked older foraminifera.
A 30,000-Year Pollen and Radiocarbon Record from Highland Sumatra as Evidence for Climatic Change
Authors: Maloney B. K. , McCormac F.G.
Published: July 2016

We examine the pollen analytical and 14C sequences from two Sumatra highland sites, Pea Bullok (2°15'N, 99°02'E) and Danau di-Atas (1°04'S, 100°46'E). The pollen diagrams do not correlate particularly well, possibly because two of the samples from Danau di-Atas analyzed by radioactive decay counting earlier should be infinite. Other complications are differences in the type of site, local topography, pollen sums used and difficulty in distinguishing between pollen taxa from local and regional vegetation. The older material from Pea Bullok was AMS dated.
Tell Es-Sultan (Jericho): Radiocarbon Results of Short-Lived Cereal and Multiyear Charcoal Samples from the End of the Middle Bronze Age
Authors: Bruins Hendrik J. , Van Der Plight Johannes
Published: July 2016

Samples from Tell es-Sultan, Jericho, were selected for high-precision 14C dating as a contribution toward the establishment of an independent radiocarbon chronology of Near Eastern archaeology. The material derives from archaeological excavations conducted by K. M. Kenyon in the 1950s. We present here the results of 18 samples, associated stratigraphically with the end of the Middle Bronze Age (MBA) at Tell es-Sultan. Six short-lived samples consist of charred cereal grains and 12 multiyear samples are composed of charcoal. The weighted average 14C date of the short-lived grains is 3306 ± 7 bp. The multiyear charcoal yielded, as expected, a somewhat older average: 3370 ± 6 bp. Both dates are more precise than the standard deviation (a) of the calibration curves and the absolute standard of oxalic acid. Calibration of the above Jericho dates is a bit premature, because several groups are currently testing the accuracy of both the 1986 and 1993 calibration curves. Nevertheless, preliminary calibration results are presented for comparison, based on 4 different calibration curves and 3 different computer programs. Wiggles in the calibration curves translate the precise bp dates into rather wide ranges in historical years. The final destruction of MBA Jericho occurred during the late 17th or the 16th century bc. More definite statements about the calibrated ages cannot be made until the accuracy of available calibration curves has been tested. Development of calibration curves for the Eastern Mediterranean region would be important.
Re-Evaluation of the Neolithic in Eastern Hungary Based on Calibrated Radiocarbon Dates
Authors: Hertelendi Ede , Kalicz Nándor , Raczky Pál , Horváth Ferenc , Veres Mihály , Svingor Éva , Futó István , Bartosiewicz László
Published: July 2016

The chief objective of this paper is to improve our understanding of the Neolithic in Eastern Hungary using absolute chronological data. To accomplish this we calibrated new measurements as well as previously published dates. The up-to-date, standardized evaluation of 261 calibrated measurements showed temporal overlaps between archaeological cultures defined on the basis of ceramic styles. The increasing number of dates suggest that the Neolithic period began at the turn of the 6th and 7th millennia bc and lasted for ca. 1500 yr in the present area of the Great Hungarian Plain (Alföld). Further research should be aimed at complementing the current data set with dates from western Hungary and establishing additional correlations among stratigraphic, typological and radiocarbon dates.
The Occupation History of the Region Between the Dvina and Lovat Rivers in Relation to the Dynamics of Environmental Change
Authors: Zaitseva G. I. , Mikliaev A. M. , Mazurkevich A. N.
Published: July 2016

We show how 14C dating may be combined with palynological and paleogeographical research to correlate human occupation history with environmental change, focusing on archaeological sites in the Dvina–Lovat River region of Russia. Cultures in this region range from Early Neolithic to the Middle Ages, ca. 5500 bc–ad 100, based on calibrated 14C ages. The dynamics of water basins in the region, related to climatic change, are one cause of population migration.
Radiocarbon Dating of the Zagreb Upper Town Prehistoric Settlement
Authors: Obelić Bogomil , Šmalcelj Marija , Horvatinčič Nada , Bistrovič Romana , Sliepčević Adela
Published: July 2016

During the 1989–1994 renovation of the Zagreb Town Museum, it became obvious that the area was inhabited in prehistoric times. We 14C dated 40 samples to determine various settlement periods. The ages of the samples span a much longer time than expected, from the Early Iron Age (Hallstatt period) to the 19th century ad. 14C dates on charcoal samples placed the remains of dwelling pits in the Hallstatt period, 8th to 4th century bc. A late La Tène settlement dated between the 4th century bc and the 2nd century ad. Medieval fortifications were identified in the western part of the complex, consisting of a well-preserved wooden structure used for construction of the royal castrum. 14C measurements on wooden planks and posts date the construction of the fortification between the 13th and 15th centuries ad and branches, beams, and tools found below the basement of the Convent of St. Clare span the 16th to the 19th century ad.
Radiocarbon Dating of Biochemically Characterized Hair
Authors: Taylor R. E. , Hare P. E. , Prior Christine A. , Kirner Donna L. , Wan Lijun , Burky Richard R.
Published: July 2016

A series of 14C determinations have been obtained on hair samples principally from Holocene contexts that have been variously pretreated to examine different means of removing potential contamination. SEM photomicrographs have documented hair surfaces before and after different pretreatments. Amino-acid composition, C/N ratios and δ13C values have been obtained to biochemically characterize these samples and provide baseline data for future comparisons with less well-preserved samples. Our data support the view that appropriately pretreated hair samples can provide accurate 14C age determinations.
Radiocarbon Dating of Prehistoric Shell from New Zealand and Calculation of the δr Value Using Fish Otoliths
Authors: Higham T. F. G. , Hogg A. G.
Published: July 2016

We calculated a new ∆R for New Zealand waters using14C dates of historic shell previously presented by McFadgen and Manning (1990), and fish otoliths dated by Kalish (1993). We obtained a new estimate of −25 ± 1514C yr. To test the accuracy of this value for correcting conventional14C marine ages, we dated shell of a variety of different species excavated at the prehistoric site of Shag Mouth, North Otago. We compared the results with a pooled mean date for terrestrial samples and calculated a local ∆R value that we found statistically indistinguishable from the new ∆R estimate for New Zealand.
14CH4 Emissions from Nuclear Power Plants in Northwestern Europe
Authors: Eisma Roos , Vermeulen Alex T. , Van Der Borg Klaas
Published: July 2016

We measured the 14C content of atmospheric methane at a 200-m-high sampling station in The Netherlands. Combined with trajectories and a transport model, it is possible to estimate the 14CH4 emissions from nuclear power plants in northwestern Europe. We demonstrate here two different methods of analyzing the data: forward modeling and an inverse method. Our data suggest that the emissions from pressurized water reactors are 260 ± 50 GBq per GW installed power per year, ca. 1.6 ± 0.4 times higher than generally assumed. We also find that, in addition to the known nuclear sources of 14CH4 (pressurized and boiling water reactors), there are two very strong sources of 14CH4 (520 ± 200 and 1850 ± 450 GBq yr−1, respectively), probably two test reactors near the sampling station.
Estimating Long-Term Carbon Accumulation Rates in Boreal Peatlands by Radiocarbon Dating
Authors: Korhola Atte , Tolonen Kimmo , Turunen Jukka , Jungner Högne
Published: July 2016

We used direct radiocarbon dates of peat samples, pollen dates and land-uplift chronology from >1300 cores comprising all or most of the Holocene in the boreal region of Finland, Estonia and Maine (USA) to obtain long-term carbon accumulation rates for boreal peatlands. The “apparent” long-term rate of carbon accumulation (LORCA; g C m−2 a−1) ranged from 4.6 to 85.8 (mean 19.9 ± 10.7), depending on the geographical location, wetland type and the age of the mire. The “true” or “actual” rate of carbon accumulation (ARCA), as derived from models for peatbog growth, was usually ca. 70% of LORCA. We studied the raised bog Reksuo more intensely in terms of growth dynamics, and we report preliminary results of the “three-dimensional” or spatial carbon accumulation rates. These results strongly contradict the concept of constant input and constant decay throughout the millennia. The study emphasizes the importance of exploring the formation and dynamics of entire mire ecosystems, and the role of carbon in these systems, in addition to studying single cores.
Radiocarbon with Gas Chromatography
Authors: Bronk Ramsey Christopher , Hedges R. E. M.
Published: July 2016

In 14C tracer studies, and when looking for modern contamination in archaeological samples, it is often necessary to measure the 14C concentration of individual chemical fractions. Gas chromatography (GC) is one method that is frequently used for separation of chemical fractions. The gas ion source at the Oxford Radiocarbon Accelerator Unit for accelerator mass spectrometry (AMS) provides the opportunity to measure fractions from a GC instrument directly. Although the first investigations are likely to be 14C tracer studies, such a GC-AMS system could find much wider application. We present results from a pilot study of the peak sensitivity, baseline stability and crosstalk of the accelerator system used in this way. We also discuss the practical considerations in developing a GC-AMS instrument for routine use.
Influence of Chromium Endowment and Surface Area of Silica-Alumina Catalysts and of Reaction Conditions on Benzene Synthesis
Authors: Becker-Heidmann Peter , Hiller Achim , Hofmann Jörg
Published: July 2016

Radiocarbon laboratories using liquid scintillation counting depend on the availability of a catalyst for benzene synthesis. One of the two commonly used is a commercially available chromium-activated silica-alumina catalyst, PKN/D1. As this catalyst will no longer be produced, we have tested similar catalysts as possible replacements. We measured benzene purity by gas chromatography and mass spectrometry, and found that chromium endowment was crucial for a proper catalyst function. The surface area of the catalyst also significantly affected benzene yield and purity. We also studied the effects of different reaction conditions of acetylene absorption and benzene desorption on benzene purity. A catalyst with half of the Cr endowment and doubled specific surface area created yield and purity comparable to PKN/D1.
Sources of Radon Contamination in 14C Dating
Authors: Horvatinčić Nada , Obelić Bogomil , Krajcar Bronić Ines , Srdoč Dušan , Bistrović Romana
Published: July 2016

We investigated the effect of radon (222Rn) contamination of samples and chemicals used for sample preparation and gas purification on the 14C age of samples. Radon count rate was monitored over several 222Rn half-lives in a proportional counter filled with methane. We analyzed ca. 240 samples of fossil and recent wood, charcoal, bone, dissolved inorganic carbon in water, travertine, peat, aquatic plants, organic soil and atmospheric CO2 for 222Rn contamination. Chemicals used for gas purification (MnO2, Mg(ClO4)2), ruthenium-coated pellets used for catalytic reduction of CO2 to CH4, and acids used for dissolution of calcareous samples (HCl and H3PO4) are also potential sources of Rn. Most geological samples contained a significant amount of Rn, as opposed to samples of wood, charcoal, aquatic plants and atmospheric CO2. We also studied Rn contamination of water samples during tritium activity measurements in a CH4-filled gas proportional counter. We found an increased count rate in the 3H channel, as well as above the 20 keV region in Rn-contaminated groundwater samples.
A Beta-Counting System Linked to a Personal Computer
Authors: Omoto Kunio
Published: July 2016

The automatic β-counting system plays a significant role in obtaining high-level reproducibility and reliability in conventional radiocarbon dating. I review here the results achieved by using the “Fully Automatic Radiocarbon Dating System” developed by Omoto (1982). Since setting up the system in 1981, I was able not only to save operator time in β counting, but also to obtain accurate dates with only minimal uncertainties. Another positive result was the introduction of the automatic voltage correction program, which produced excellent results for counting sample materials over a long period.
Radiocarbon Intercomparison Studies at the Rudjer Bošković Institute
Authors: Krajcar Bronić Ines , Horvatinčić Nada , Obelić Bogomil , Bristrović Romana
Published: July 2016

The Radiocarbon Tritium Laboratory at the Rudjer Bošković Institute participated in all three radiocarbon intercomparison studies. The first International Collaborative Study (ICS) showed that the age of organic samples measured at our laboratory is ca. 70 yr younger than the median ICS value. After introducing a slight modification in our chemical pretreatment procedure by acidifying samples after alkaline treatment, we obtained excellent agreement between our results and the median values reported by two subsequent intercomparisons (IAEA, TIRI) without any laboratory bias.
Environmental Influences on Dietary Carbon and 14C Ages in Modern Rats and Other Species
Authors: Beavan-Athfield Nancy R , McFadgen Bruce G , Sparks Rodger J
Published: July 2016

Diet can play a significant role in anomalous radiocarbon ages derived from bone and other tissues when the food web incorporates depleted 14C reservoirs, such as the marine environment. Dietary effects from a post-bomb carbon variation have also been found in modern invertebrates and populations of Rattus exulans (Beavan and Sparks 1998). We now present the effect on absolute percent modern (pMC) and the conventional radiocarbon age (CRA) of a modern aquatic/terrestrial food web in a volcanic zone of the North Island, New Zealand. At Lake Taupo, geothermal venting transfers 14C depleted carbon to lake waters, which aquatic plants fix into the food chain; depleted 14C is shown to then pass on to shellfish, waterfowl, and Norway rat (Rattus norvegicus). The geothermally induced 14C variations from modern atmospheric pMC and CRA can increase apparent 14C ages by >2000 years.
Estimation of Inbuilt Age in Radiocarbon Ages of Soil Charcoal for Fire History Studies
Authors: Gavin Daniel G
Published: July 2016

Radiocarbon age determinations of wood charcoal are commonly used to date past forest fire events, even though such ages should be greater than the fire event due to the age of the wood at the time of burning. The difference in the14C-derived age of charcoal and the time-since-fire (the “inbuilt age”) may be considerable in some vegetation types and thus must be estimated before interpreting fire dates. Two methods were used to estimate the potential range of inbuilt age of soil charcoal dated to determine ages of forest fires on the west coast of Vancouver Island (Canada). First, 2614C ages on charcoal in surficial soil were compared directly with ages of forest fire determined by tree-ring counts, suggesting inbuilt ages of 0–670 years. Second, a simulation model that uses estimated fuel loads, fuel consumption, charcoal production, and the ages of charred wood (time since wood formation), suggests that the combination of slow growth rates and slow decay rates of certain species can account for inbuilt ages of more than 400 years in this forest type. This level of inbuilt age is large enough such that the actual age of a fire may not occur within the 2σ confidence interval of a calibrated charcoal14C age determination, and thus significantly affect the interpretation of fire dates. A method is presented to combine the error of a calibrated14C age determination with the error due to inbuilt age such that the larger adjusted error encompasses the actual age of the fire.
Data Analysis and Calibration of Radiocarbon Dating Results from the Cemetery of the Marquises of Jin
Authors: Lu Xiangyang , Guo Zhiyu , Ma Hongji , Yuan Sixun , Wu Xiaohong
Published: July 2016

The chronology study of the cemetery of Marquises of Jin is valuable to improving the chronological table of Marquis of Jin family. It is also helpful for improving the chronological table of the Zhou Dynasty. The samples were measured at Peking University (PKUAMS). We also made an interlaboratory check with Isotrace to ensure the accuracy. By careful analysis of archaeological information, we built different models and calibrated by OxCal. The calibration results, both sampling contexts and estimations, are in very good agreement with the historical record. Because the dates of some events correspond to the special part of the curve, the calibration gets very high precision. The calibration result of tomb M93 suggests that its host is Marquis Shangshu instead of Marquis Wen.
AMS Radiocarbon Dating of a Shell Fishhook from Santa Rosa Island, California
Authors: Rick Torben C
Published: July 2016

Several single-piece shell fishhooks from CA-SRI-43 on Santa Rosa Island were dated by association to roughly 5500 cal BP and were argued to be among the oldest specimens in the region. Direct accelerator mass spectrometry (AMS) radiocarbon dating of one of these hooks provided a date of 560 cal BP, however, making it about 5000 yr younger than originally presumed. This younger date is more consistent with the regional shell fishhook chronology and demonstrates the importance of obtaining direct AMS 14C dates to refine artifact and site chronologies.
Reservoir Offset Models for Radiocarbon Calibration
Authors: Jones Martin , Nicholls Geoff
Published: July 2016

The purpose of a reservoir offset is to enable the application of calibration data (μ(θ), e.g. Stuiver et al. 1998) developed for one reservoir (primary reservoir) to CRAs from another (secondary reservoir), for example the use of a hemispheric offset for terrestrial samples (Barbetti et al. 1995; McCormac et al. 1998; Sparks et al. 1995; Vogel et al. 1986, 1993). The usual approach has been to define the activity of the secondary reservoir as some form of constant offset (with error) from the primary reservoir (e.g. Higham and Hogg 1985; McFadgen and Manning 1990). In this case, all CRAs from a secondary reservoir are given the same offset. The value of this common offset is not known exactly, but any uncertainty in the measured value of the offset corresponds to uncertainty in the common offset for all CRAs. However, the standard procedure for incorporating offset error into CRAs incorrectly allows a different offset for each CRA. The offset for each CRA is incorrectly allowed to vary by the measurement error reported for the offset value. Technically, the offset is incorrectly treated as varying independently from one CRA to the next, when in fact it is a single parameter for the secondary reservoir in question. In light of this, the calibrated date distributions will be incorrect for CRAs where an offset has been applied and the standard approach to offset error treatment has been used. In many cases, the differences between correct and incorrect calibrated date distributions will be insignificant. However, in some cases significant differences may arise and other approaches to treating the error associated with offsets need to be adopted.
Initial Human Colonization of the Americas: An Overview of the Issues and the Evidence
Authors: Fiedel Stuart J
Published: July 2016

Ever since José de Acosta's prescient speculation, in 1590, that Native Americans were descended from “savage hunters” who had followed game animals across a land bridge from northeastern Asia into northwestern America (Acosta 1604), most serious scholars have assumed that this was the migration route. The main point of dispute has been the date when the ancestral Asians made the crossing. After many nineteenth-century claims of the discovery of stone tools or bones of “early man” failed to withstand scientific scrutiny, a conservative reaction set in, embodied by the hyper-skeptical Aleš Hrdlička of the Smithsonian Institution. Hrdlička dismissed all claims of a human presence in the Americas prior to about 5000 years ago.
Radiocarbon-Based Chronology of the Paleolithic in Siberia and Its Relevance to the Peopling of the New World
Authors: Vasil'ev Sergey A , Kuzmin Yaroslav V , Orlova Lyubov A , Dementiev Vyacheslav N
Published: July 2016

The territory of Siberia is of crucial importance for the study of early human dispersal and the peopling of the New World. A Siberian Paleolithic Radiocarbon Database has been compiled. The Database allows us to compile a chronolgical framework for human colonization of Northern Asia. There are 446 14C dates for 13 Middle and 111 Upper Paleolithic sites older than around 12,000 BP. Seventeen percent of the dates were obtained by the accelerator mass spectrometry (AMS) technique, and the remaining 83% are conventional. From the viewpoint of the spatial distribution of the 14C-dated sites, the majority of these are located at the Yenisey River Basin, Transbaikal, and the Altai Mountains. The general outline of the Upper Paleolithic colonization of Siberia is given here. The earliest traces of modern human occupation are dated to around 43,000–39,000 BP in the southern part of Siberia. It seems that by around 13,000 BP, almost all of northern Asia, including the extreme northeastern Siberia had been colonized by modern humans. We discuss some controversial problems that have provoked heated debates in current Russian archaeology. Notable among these are the surprisingly early AMS dates for the Early Upper Paleolithic, the age of the Dyuktai culture of Yakutia, the problem of human presence in Siberia at the time of the Last Glacial Maximum (20,000–18,000 BP), and the timing of the initial settling of the Chukchi Peninsula and northeastern Siberia.