bluuebunny/crossref_metadata_2025 huggingface dataset:
University of Cambridge Natural Radiocarbon Measurements IX
Authors: Switsur V. R. , Hall M. A. , West R. G.
Published: July 2016

The University of Cambridge Radiocarbon Dating Laboratory has been completely rebuilt and modernized, incorporating new techniques developed here for the various stages of measurements. Sample radioactivity is measured in gas proportional counters after conversion to highly purified CO2. Four counters are mounted within a single anticoincidence shield consisting of plastic scintillation material. This is surrounded by a graded cosmic ray shield of low radioactive steel, boron loaded wax, and finally, about 16 tons of ancient low radioactive lead blocks. The electronics are all solid state devices except for the stabilized high voltage supplies.
University of Rome Carbon-14 Dates VIII
Authors: Alessio M. , Bella F. , Improta S. , Belluomini G. , Cortesi C. , Turi B.
Published: July 2016

This list includes age measurements carried out from December 1968 to October 1969. Archaeologic samples are from Italian and Swat (W Pakistan) territories. All geologic samples come from Italian territory. Chemical techniques remain the same (Bella and Cortesi, 1960; Alessio, Bella, and Cortesi, 1964).
Pretoria Radiocarbon Dates I
Authors: Vogel J. C. , Marais M.
Published: July 2016

In 1969 radiocarbon dating facilities were established at the National Physical Research Laboratory of the C.S.I.R. in Pretoria (25° 43′ S Lat, 28° 21′ E Long; alt 1500 m). The counters are situated in an underground room built of selected concrete and covered by ca. 12 m earth. In this room, the nucleonic component of cosmic radiation is practically absent and the meson flux is reduced by a factor of 3.5 as compared to the surface at sea level in Groningen, Netherlands. A neutron monitor which registers 30 cpm on the surface, counts ca. 0.1 cpm in the underground room.
University of Georgia Radiocarbon Dates I
Authors: Noakes John E. , Brandau Betty Lee
Published: July 2016

The Geochronology Laboratory of the University of Georgia was established in the fall of 1969. The laboratory is housed in the basement of the Geology Building and is under the direction of the General Research Department. Radiocarbon dating facilities are the first to be developed in the laboratory. Other methods will be employed to date a wide spectrum of samples over extensive age ranges. Facilities of the laboratory are also available to colleges, universities, and institutions for teaching and research.
Glasgow University Radiocarbon Measurements VII
Authors: Baxter M. S. , Farmer J. G.
Published: July 2016

This list presents results obtained during 1971-1972 and is a continuation of research evaluating natural C14 levels for which data have been published previously (Baxter et al., 1969; Baxter and Walton, 1970; Farmer et al., 1972). The results of these studies are presented as δC14 and Δ values based on age-corrected activities, although this correction is very small. Errors quoted are lσ counting uncertainties only. Pretreatment procedures are outlined in the text and analytical methods are essentially unchanged. Gas proportional counting of CH4 in a 0.5L detector is employed (Baxter et al., 1969). Mass spectrometric analyses are performed to a precision of 0.1‰ (± 2σ) on a V.G. Micromass 602B stable isotope mass spectrometer.
Belfast Radiocarbon Dates VI
Authors: Smith A. G. , Pearson G. W. , Pilcher J. R.
Published: July 2016

The dating equipment and operating conditions remain essentially as previously described. This list includes some small samples counted at a filling pressure equivalent to 76cm Hg. at 20°C. Carbon isotope ratios were obtained and calculated as described (R., 1973, v. 15, p. 212). All samples are from Ireland.
University of Lund Radiocarbon Dates XI
Authors: Håkansson Sören
Published: July 2016

Most of the 14C measurements reported here were made between October 1976 and October 1977. Equipment, measurement, and treatment of samples are as reported previously (R, 1968, v 10, p 36-37; 1976, v 18, p 290).
Marine Resources Research Institute Radiocarbon Dates II
Authors: Mathews Thomas D
Published: July 2016

Samples reported in this date list are primarily geologic specimens collected from coastal locations in South Carolina and Florida. Sample material was predominantly shells, with emphasis on single shell dates rather than multiple shell dates. Archaeologic samples from sites either directly above or adjacent to the geologic sampling location were collected whenever possible to provide an upper time limit on the shell deposits.
Tartu Radiocarbon Dates VIII
Authors: Ilves E
Published: July 2016

The present list includes 66 dates of geologic samples determined using the liquid-scintillation 14C metod at the Geobiochemical Laboratory of the Institute of Zoology and Botany, Academy of Sciences, Estonian SSR. Benzene synthesized from wood dating from 1850 ± 10 yr served as a reference standard. All radiocarbon dates have been calculated using 5568 ± 30 yr before ad 1950 as the half-life of 14C.
Tallinn Radiocarbon Dates V
Authors: Punning J M , Rajamäe R , Ehrenpreis M
Published: July 2016

The following list comprises age measurements carried out during 1976 and 1977. The activity of14C was computed by one- and two-channel scintillation devices (Punninget al, 1976; 1977). Ages are calculated using a half-life of 5568 ± 30 years for14G with NBC oxalic acid as a reference standard. All dates are reported in years before 1950.12C/13C measurements were not performed and results are not corrected for13C fractionation.
University of Georgia Radiocarbon Dates VI
Authors: Brandau Betty Lee , Noakes John E
Published: July 2016

The Geochronology Laboratory has recently changed its name to the Center for Applied Isotope Studies to reflect its steady and diversified expansion since its conception in 1969. Initially the laboratory was set up to offer age dating services to personnel at the University of Georgia. Subsequently, the laboratory expanded its activities so as to enable it to participate in studies of an applied and basic research nature.
The Effect of Fossil Fuel and Biogenic CO2 on the 13C and 14C Content of Atmospheric Carbon Dioxide
Authors: Mook W G
Published: July 2016

The normalization of a measured δ14C value of atmospheric CO2 to a δ13C value of − 25‰ does not take into account the presence of fossil fuel and biogenic CO2. In this paper, we try to assess these contaminations as well as the proper 14C content of “clean air”.
Some Possibilities for the Development of 14C Measurements by Liquid Scintillation Counting
Authors: Rajamäe R , Punning J M
Published: July 2016

The possibilities of widening the ranges of usage of scintillation counters are studied. As a result of the introduction of the active guard, the background in 14C channel reduces 30 to 75 percent and the stability of background increases. The application of quartz vials and a plastic scintillator as an active guard establishes 14C activity in small amounts of scintillation cocktail (up to 0.1g C) and dates samples with older ages (up to 57,000 years). The parameters of devices are given in case of different amounts of scintillation cocktail.
Radiocarbon Activity Measurements of Oolitic Sediments from the Persian Gulf
Authors: Šilar Jan
Published: July 2016

Radiocarbon activity of successive parts of Pleistocene and Holocene ooids and mollusk shells from the Persian Gulf, Kuwait, was measured. The inner part of the ooids showed the lowest activity and the cement between grains the highest. Radiocarbon activities correspond to the general stratigraphy and to the position of the sediments. Radiocarbon ages of Pleistocene sediments seem to be very low due to recrystallization of aragonite. Higher radiocarbon activity of cement indicates that atmospheric carbon dioxide was involved in the subaerial diagenetic process. The radiocarbon age of well-preserved mollusk shells seems to be lower than their allegedly Pleistocene geologic age.
Gas Exchange Rate Measurements in Natural Systems
Authors: Broecker W S , Peng T-H , Mathieu G , Hesslein R , Torgersen T
Published: July 2016

Rates of CO2 exchange across the air-water interface in oceans and lakes measured to date by the L-DGO group are summarized. They range from 3 to 38 moles/m2/yr. The possible causes for this range include the differences in salinity, mean wind speed, and pH. Wind tunnel studies comparing fresh water and sea water are required before a satisfactory explanation can be found.
Climate Periods in Trees and A Sea Sediment Core
Authors: Pandolfi Louis J , Kalil Emil K , Doose Paul R , Levine Lawrence H , Libby Leona Marshall
Published: July 2016

Chemical components in a sea sediment core from the Santa Barbara Basin show the same periodic variations as do stable isotope variations in a Japanese cedar.
Radiocarbon Dating of Earthquakes
Authors: Berger Rainer , Kaufman Thomas S
Published: July 2016

Within the United States, the State of California ranks first in recorded earthquake frequencies. Annually, thousands of shocks are registered on seismometers and many hundreds are actually noticed directly by Californians. In modern times, about one quake per year, destructive to property, has occurred, yet the very large and disastrous events approaching magnitude 8 and higher on the Richter scale are spaced a few decades apart: 1857 in Southern California centered on Tejon Pass, 1872 in the Owens Valley, and 1906 in San Francisco. Unfortunately, the historical record for earthquakes is short in California when compared with accounts for Europe or China, both of which list quakes over a time period of some 2000 to 3000 years. In California, the first historically noted event dates to barely 200 years ago, when in 1769, members of an expedition of the Spanish explorer Gaspar de Portola were knocked to the ground along the Santa Ana River during a large earthquake.
Macs: An Accelerator-Based Radioisotope Measuring System
Authors: Purser Kenneth H , Liebert Reuel B , Russo Carl J
Published: July 2016

A description is given of an accelerator-based radioisotope measuring system, being supplied to the Universities of Arizona and Toronto and in part to the University of Oxford. This system will be capable of measuring 14C/12C and 13C/12C ratios in milligram samples of cracked acetylene. At present 200µg of carbon obtained from cracked acetylene appears to be adequate for an isotopic ratio determination. Previous performance and new calculations indicate that a precision better than 1 percent will be achieved in a half-hour period only limited by counting statistics. A precision of 0.2 percent will be obtained in a ten-hour period. Using a carbon sample with an age greater than 60,000 years, the measured background 14C/12C ratio will be less than 0.07 percent of modern.
Soil Dating By Fractional Extraction of Humic Acid
Authors: Kigoshi Kunihiko , Suzuki Nobuko , Shiraki Mari
Published: July 2016

The addition of organic materials derived from the upper soil layer yields, for samples at greater depth, younger 14C dates than the date of deposition. To find a criterion for the contamination with younger carbon in a soil sample, we examined the radiocarbon concentrations in two humic acid fractions and humin taken from the same sample. The humic acid extracted from a soil sample was divided into two fractions HA1 and HA2. HA1 is the first fraction extracted by 30 minutes' heating with 2 percent NaOH solution, and HA2 is the second fraction extracted by 2 hours' heating with 2 percent NaOH solution after the extraction of HA1. The residue was assumed as the humin (HM).

Many of the peat or soil samples taken from the layer just above the nonpermeable layer contain appreciable amounts of organic materials transported from the upper layer after the sedimentation of the deposits. For the limited number of cases tested here, there is a trend in which the contaminants are selectively extracted by HA1 or HA2. When the soil samples are contaminated the ages of the HA1 and HA2 fractions appeared to differ widely in most cases. Agreement between the HA1, HA2, and HM ages may be used as a criterion for the reliability of the soil dating.
Radiocarbon Dating of Calcareous Tufa: How Reliable Data can we Expect?
Authors: Srdoč Dušan , Obelic Bogomil , Horvatinčic Nada , Sliepčevic Adela
Published: July 2016

Systematic dating of tufa samples has been undertaken to establish a chronology of tufa deposits in Plitvice National Park, Yugoslavia. We conclude that tufa samples give reproducible data within the time span of ≈ 40,000 years up to recent. The 14C/12C ratio of carbon in the ambient biosphere and hydrosphere gives a detailed picture of the distribution of carbon isotopes in the investigated system. Despite the susceptibility of calcareous material to ambient conditions in the hydrosphere, the original 14C composition of tufa has not been substantially changed. A vertical profile which was cut in tufa during pathway construction showed that the tufa isochrones run vertically in the investigated area. The vertical isochrones and the 14C gradient were horizontal due to tufa build-up in Plitvice National Park which occurs on vertical escarpments that have been flooded. The relatively uniform radiocarbon content of most tufa deposits indicates redistribution of radiocarbon during the formation period. While detailed stratigraphy is often obscured, a general chronology of tufa deposits in the investigated area has been established.
14C Interlaboratory Comparison in the UK: Experiment Design, Preparation and Preliminary Results
Authors: Otlet R L , Walker A J , Hewson A D , Burleigh R
Published: July 2016

An interlaboratory comparison experiment for 14C measurements has been organized jointly by the Harwell and British Museum laboratories to include the working radiocarbon laboratories of the United Kingdom. The experiment has been run along the lines of that organized by the IAEA for tritium and has explored the problems of sample preparation, verification of equivalent levels, and presentation of results. Samples of benzene representing 5 age equivalent levels between twice modern and 20,000 years old have been prepared and distributed for measurement either by direct counting (liquid scintillation) or full process tests. Preliminary results received show excellent agreement both between laboratories and in comparison with the known relative activities of the prepared solutions. The possibility of extending the experiment to cover different sample types and a wider distribution of testing laboratories is briefly discussed.
New National Bureau of Standards Contemporary Carbon-14 Standards
Authors: Cavallo L M , Mann W B
Published: July 2016

In 1957 the National Bureau of Standards (NBS) agreed, at the request of James R Arnold, to store and distribute an oxalic acid contemporary carbon-14 standard. In 1978 stocks of this standard were practically gone. We approached Chas Pfizer and Company, Inc, which had provided the original 1000 pounds of oxalic acid to Dr Arnold to see if they could provide another one-batch lot of 1000 pounds of oxalic acid to replace the old standard. This they did generously, at no cost to NBS. The oxalic acid was prepared by fermentation of French beet molasses from the 1977 spring, summer, and autumn harvest using Aspergillus niger var. The acid was separated from the broth as the insoluble calcium salt and reconverted to free acid using sulfuric acid. The free acid was then crystallized, redissolved, filtered, recrystallized, and dried.
Radiocarbon Dating of Ceramic Materials: Progress and Prospects
Authors: De Atley Suzanne P
Published: July 2016

Although initial studies in the 1960's established the feasibility of applying the radiocarbon technique directly to ceramics, subsequent analyses have revealed this category of materials to be more complex than previously believed. Consideration of the points at which various types of organic carbon are introduced into ceramic materials by natural or human agencies allows more effective screening of potential sherd samples. It also suggest ways to overcome some of the limiting factors involved in dating ceramics.
Southern Rhodesian Radiocarbon Measurements I
Authors: Robins P. A. , Swart E. R.
Published: July 2016

The first series of C14 dating measurements made in the Gulbenkian Radiocarbon Dating Laboratory, which came into operation in October 1962, are reported in the following list.
University of Texas Radiocarbon Dates II
Authors: Tamers M. A. , Pearson F. J. , Davis E. Mott
Published: July 2016

The Radiocarbon Dating Laboratory of the University of Texas was reorganized in late 1962. The dates reported in this list were obtained from February to November, 1963. The laboratory uses liquid scintillation counting with benzene solutions (Tamers, Stipp, and Collier, 1961; Noakeset al., 1963). The chemical synthesis has been modified and improved in several ways in order to permit one worker to produce a sample per day.
Miami Natural Radiocarbon Measurements III
Authors: Rusnak Gene A. , Bowman Albert L. , ӧstlund H. Gӧte
Published: July 2016

The list of dates grouped below is a continuation of work reported in our earlier lists. In one case (Core A 254-BR-C), an extensive sequence of dates is reported which, for completeness, includes some data presented in an earlier report (Miami II, 1963).

We continue to use a 1.0-L CO2 proportional counter operating a 3 atm pressure (see Stockholm V for details). Except for the early incorporation of a counter for tritium analyses within our present shielding house and switching over to transistorized electronics, we do not anticipate changes in our set-up.

Wherever possible we have entered the δC13 corrected date as well as the δC13 value determined from that sample. An apparent 400-yr sea-surface carbonate age is subtracted from the calculated age of marine carbonate materials, but not for organic material (Miami I and Miami II).
UCLA Radiocarbon Dates III
Authors: Fergusson G. J. , Libby W. F.
Published: July 2016

The measurements reported in this list have been made in the Isotope Laboratory of the Institute of Geophysics during 1963 and are a continuation of the work reported previously (UCLA I and UCLA II). The same counting procedure—CO2 proportional counting at 1 atm pressure in a 7.5 L counter with three energy channels—continues in use. No barometric effect on the background has been observed, presumably because of the combination of fairly constant barometric pressure in this area and the location of the equipment on the ground floor of a five storey building. Dates continue to be calculated on the basis of a C14 half life of 5568 yr according to the decision of the 1962 Cambridge Conference (Godwin, 1962). The modern standard has been taken as 95% of NBS oxalic acid for all organic samples, while for carbonate material such as shells and tufa, dates have been computed on the basis of estimates of the corresponding contemporary C14 activity (Broecker and Walton, 1959) as indicated in the description accompanying the results.
Geological Institute Radiocarbon Dates III
Authors: Cherdyntsev V. V. , Kind N. V. , Zavel'Skiy F. S. , Forova V. S. , Churikova I. V. , Sulerzhitskiy L. D.
Published: July 2016

Charcoal from campsite hearth from Zozov village, Rovno Oblast [Rovno city: 50° 30′ N Lat, 26° 12′ E Long], Ukrainian SSR. Kut hamlet, semi-subterranean Dwellings VII and VIII. Corded pottery culture; (cf. Gimbutas, 1956 [D.B.S.]). Subm, by I. K. Sveshnikov, Inst. of Social Studies, L'vov.
Birmingham University Radiocarbon Dates III
Authors: Shotton F. W. , Blundell D. J. , Williams R. E. G.
Published: July 2016

Measurements have continued with the 6 L counter. A counter of similar design but with 1 L volume has recently been brought into operation. Despite replacement of the teflon parts, the 1.5 L Oeschger-type counter has not worked consistently and has not been used for dating. Results are not corrected for δ C13. Errors quoted refer only to the standard deviation calculated from a statistical analysis of count rates and the Libby half-life of 5570 ± 30 yr.

Alkali pretreatment is used for all samples of charcoal, peat, wood, and plant material provided they are of sufficient quantity. It is now standard practice to boil the sample in 5% HCl solution and filter, both before and after boiling it in 2% NaOH solution. Between each treatment it is washed in boiling distilled water and is finally oven dried at 110°C. Concentrations of acid and alkalis are varied to suit each sample but the sequence of the pretreatment is always the same. In some cases a humate extract is obtained by precipitation with weak acid from the alkali solution filtrate.

The collagen fraction is obtained from samples of bone using the method of Krueger (1966) by treatment with dilute acid under reduced pressure. The gas evolved during the treatment is usually discarded but is occasionally retained and dated as the mineral fraction.

After mechanical cleaning, samples of shell are dissolved in stages with 6N HCl to divide them into two or three fractions corresponding to the outer, middle, and inner layers of the shell. Normally the outer fraction is discarded when three fractions have been prepared.
British Museum Natural Radiocarbon Measurements VI
Authors: Barker Harold , Burleigh Richard , Meeks Nigel
Published: July 2016

Dates listed below are based on measurements made up to May 1968, and cover a period during which the technique of gas proportional counting using CO2 was gradually replaced by liquid scintillation counting using benzene. The gas counting measurements were carried out by the method and techniques previously described (Barker and Mackey, 1968) the only modifications being the replacement of some old electronic units by more stable solid-state equipment; proportional counting results are indicated in the text by (P) at the end of the relevant sample descriptions. Liquid scintillation counting, which is now the preferred method in this laboratory, is carried out using a Packard Tri-Carb liquid scintillation spectrometer model 3315/AES fitted with selected low-noise quartz-faced photomultipliers. Normally 3 ml of benzene is prepared from each sample. This is dissolved in 12 ml of scintillation grade toluene containing 5 gm/liter of scintillator (PPO) and the solution is measured in a standard low-potassium glass vial at a temperature of 0°C. Photomultiplier E.H.T., amplifier, and channel width settings are optimized for C14, and measurements are carried out at ca. 65% efficiency of detection for C14 to eliminate interference from any tritium which may be present in the benzene. Under these circumstances the background is approx. 8.6 cpm and the modern (95% Aox) is approx. 24.0 cpm. Samples are counted in groups of 3 to 5 together with background and modern reference samples and are measured for at least one week, the instrument being set to cycle at 100 min intervals. In this period, the counts accumulated are such that the background is always measured to a statistical accuracy of better than 1% and most other samples to a higher accuracy than this. Background and modern counts used in the calculation of each result are only those relevant to the period of measurement of that particular sample. Statistical analysis of groups of replicate measurements made under these conditions over a very long period of time has demonstrated the excellent long-term stability of the equipment and indicates that the technique is quite capable of achieving results of very high statistical accuracy when required.
Gif Natural Radiocarbon Measurements III
Authors: Delibrias G. , Guillier M. T. , Labeyrie J.
Published: July 2016

The dates detailed below are a selection of C14 dates obtained from February 1966 to December 1967 for geologic samples. The method is essentially the same as described previously in Radiocarbon, 1966, v. 8 p. 74-95. All samples were subjected to pretreatment, differing in individual cases, to remove contamination. On one of our three installations, modern transistorized equipment replaced the original electronics.

All dates reported have been calculated on the assumed half-life of 5568 yr for C14, and of 1950 as the reference year.
Age Reporting of Very Old Samples
Authors: Walanus Adam , Pazdur Mieczysław F
Published: July 2016

Problems of the statistical interpretation of radiocarbon age measurements of old samples are discussed, based on the notion of fiducial probability distribution. A probability density function of age has been given. A detailed discussion of different facets of the probability distribution of age has led us to the confirmation of the use of 2σ as the best limiting value between the regions of finite and infinite dates. It has been proposed to make use of the principle of constant probability P = 0.68 in the regions of both finite and infinite ages instead of the criterion N + kσ.
University of Miami Radiocarbon Dates XVIII
Authors: Johnson R A , Stipp J J
Published: July 2016

The following radiocarbon dates are a partial list of samples measured for a variety of projects and materials since August 1979. Chemical and counting procedures remain the same as indicated in R, v 20, p 274-282.
Studies Towards a Method for Radiocalcium Dating of Bones
Authors: Kutschera Walter , Ahmad Irshad , Billquist P J , Glagola B G , Furer Karen , Pardo R C , Paul Michael , Rehm K E , Slota P J , Taylor R E , Yntema J L
Published: July 2016

We made preliminary AMS measurements of 41Ca/Ca ratios in bone and limestone specimens with the Argonne Tandem-Linac Accelerator System (ATLAS). We were able to avoid pre-enrichment of 41Ca used in previous experiments due to a substantial increase in Ca-beam intensity. Most of the measured ratios lie in the 10-14 range, with a few values below 10-14. In general, these values are higher than the ones observed by the AMS group at the University of Pennsylvania. We discuss possible implications of these results. We also present the current status of half-life measurements of 41Ca and discuss 41Ca production processes on earth.
Liquid Scintillation Counting in the London Underground
Authors: Bowman Sheridan
Published: July 2016

At the 12th International Radiocarbon Conference held in Trondheim, the potential of the London Underground as a site for liquid scintillation counting was considered (Bowman, 1986). This was discussed in light of a survey of three possible locations using a portable gamma-ray spectrometer. Two liquid scintillation counters, a Packard 3255 and an LKB “Kangaroo”, have now been successfully installed in a vault which is some 30m below ground. The reduction in background count rates achieved is discussed, together with other improvements made to the counting system.
The Continental European Suess Effect
Authors: Levin Ingeborg , Schuchard Joachim , Kromer Bernd , Münnich K O
Published: July 2016

Observations of 14C in atmospheric CO2 at four different sites in central Europe, Heidelberg, Westerland, Schauinsland and Jungfraujoch have enabled us to determine individual fossil-fuel contributions to atmospheric CO2 concentration. The data clearly show a decrease of fossil-fuel CO2 with distance from anthropogenic source regions. At Heidelberg during winter we observe 14C/12C ratios up to 10% lower than at the clean air mountain station Jungfraujoch in the Swiss Alps, corresponding to an anthropogenic CO2 contamination level of ca 10% at the Heidelberg site. The Schauinsland and Westerland winter fossil-fuel CO2 concentrations are only ca 1.5 and 2% of the mean concentration, respectively. Our results indicate a strong seasonality in the European fossil-fuel CO2 source with ca 50% lower CO2 emissions during summer if compared to winter fossil-fuel CO2 release. This effect may significantly contribute (by 1–2 ppm) to the observed annual cycle of atmospheric CO2 concentration in northern mid-latitudes.
Radiocarbon Dating of Travertine Deposits, Arbuckle Mountains, Oklahoma
Authors: Srdoč Dušan , Chafetz Henry , Utech Nancy
Published: July 2016

Travertine deposits occur abundantly at past and present sites of waterfalls in the Arbuckle Mountains region of Oklahoma. This area (1600km2) consists of folded and faulted Prepaleozoic and Paleozoic rocks, with abundant outcrops of Paleozoic carbonate rocks. Samples of recently deposited and old travertine from the Turner Falls area were collected during a 1987 field trip and analyzed for 13C, 14C and 18O content. The aquatic chemistry of travertine depositing creeks was investigated systematically and compared with those of similar areas in SE and central Europe.
Anthropogenic 14C Variations in Atmospheric CO2 and Wines
Authors: Burchuladze A A , Chudý Martin , Eristavi I V , Pagava S V , Povinec Pavel , Šivo Alexander , Togonidze G I
Published: July 2016

As an extension of the Bratislava – Tbilisi collaboration, thermonuclear bomb-produced 14C variations in atmospheric CO2 of Bratislava (1967–1987) and in annually produced Georgian wines (1950–1987) are discussed. 14C produced in bomb tests performed in the atmosphere has considerably modified the natural 14C levels in the atmosphere and biosphere. Measurements of 14C in monthly samples of atmospheric CO2 show typical seasonal variations with maxima in summers and deep minima in winters. There is very good agreement between 14C measured in CO2 and in wine samples. Four maxima (1959, 1964, 1970 and 1978) were identified in the wine data. Our results confirm that wines prepared from annually grown grapes without any addition of other substances are good indicators of the 14C content of atmospheric CO2.
Carbon Uptake in Aquatic Plants Deduced From Their Natural 13C and 14C Content
Authors: Marčenko Elena , Srdoč Dušan , Golubić Stjepko , Pezdič Jože , Head M J
Published: July 2016

δ13C and 14C activity measurements were made on terrestrial, marsh and aquatic plants growing in their natural habitat of the Plitvice Lakes in northwest Yugoslavia. δ13C values were ca −47 for aquatic mosses, which indicate that the carbon source was dissolved inorganic carbon (DIC) from alkaline karst waters, following a C3 pathway, and ca −25 for marsh plants, indicating the carbon source was atmospheric CO2. 14C activity of true aquatic plants and submerged parts of helophytes was close to 14C activity of DIC, whereas that of emergent parts of helophytes and terrestrial plants was similar to atmospheric CO2 activity. Aquatic plants which use DIC in freshwater for their photosynthesis are not suitable for 14C dating, unless the initial activity of incorporated carbon is known. δ13C values of plant material also depend on the carbon source and cannot be used for 14C age correction.
Radiocarbon Chronology and Magnetic Susceptibility Variation in Kumaon Lake Sediments
Authors: Kusumgar Sheela , Agrawal D P , Sharma Prabhakar
Published: July 2016

This study was carried out to determine time controls of erosion and sedimentation in the catchment area and lakes of the Naini Tal district in the Kumaon Himalayas. We present here our preliminary data from five lakes, Beon Tal, Garud Tal, Sukha Tal, Bhim Tal and Kamal Tal (Naukuchia Tal). A number of 14C dates are now available to estimate the sedimentation rate of the five lakes and magnetic susceptibility (xL; xfd) variation to determine the signature of sediment source. High xfd values indicate a higher proportion of soil component generally characterized by a slower rate of deposition, and low xfd values with a higher rate of sedimentation indicate rock-debris-derived sediment. A 14C chronology enables us to estimate the mean sedimentation rate whereas rock magnetic properties help us to characterize the type of source responsible for sedimentation.
Dating of the Upper Pleistocene Lithic Industry of Sardinia
Authors: Hofmeijer G Klein , Alderliesten C , Van Der Borg K , Houston C M , de Jong A F M , Martini Fabio , Sanges Mario , Sondaar P Y , de Visser J A
Published: July 2016

During an excavation of 1986 and 1987, a joint team from Utrecht, Siena and the Soprintendenza di Sassari e Nuoro, found a pre-Neolithic lithic industry in Corbeddu Cave, Oliena, Sardinia, which was dated to 8000–17,000 bp. The artifact typology is different from that of the mainland of the same period. The lithic and bone artifacts suggest an endemic isolated economy of the Upper Pleistocene in Sardinia.
Systematic Biases in Results of the International Collaborative Study and Their Probable Sources
Authors: Pazdur Mieczysław F , Awsiuk Romuald , Goslar Tomasz , Pazdur Anna
Published: July 2016

Results of the International Collaborative Study show an unexpectedly large scatter of individual dates as well as systematic biases. Very high values of linear correlation coefficients are observed for all results of Stage 2 and for benzene samples of Stage 1. We observed moderate correlations for carbonate samples and the lowest for natural samples of wood and peat of Stage 3. The correlation is practically negligible among results obtained in different stages. The probable reasons for such effects are seen in medium-term changes in the calibration of the counting systems.
High-Precision Intercomparison at Isotrace
Authors: Beukens Roelf P
Published: July 2016

I conducted a high-precision comparison at the 0.2% to 0.3% level with samples supplied by the radiocarbon laboratory of the Quaternary Research Center at the University of Washington (QRC). Four samples with ages ranging from modern to > 50,000 BP were dated in a blind test. The absence of cosmic-radiation background in AMS dating is a major advantage for dating samples > 35,000 BP. The reliability of AMS dates > 35,000 BP depends entirely on understanding the contamination processes. By comparing results with laboratories capable of sample enrichment, such as QRC, it is possible to identify and estimate the intrinsic 14C in the background samples as well as the contamination introduced by sample preparation.
Harwell Radiocarbon Measurements X
Authors: Walker A J , Young A W , Otlet R L
Published: July 2016

This is the third of the series of lists of English archaeologic dates submitted to Harwell for measurement by the Historic Buildings and Monuments Commission for England and Wales within a prescribed contractual period. This list of 155 dates covers the period April 1987 to March 1988 and results are reported whether the associated projects are completed or on-going.
Liquid Scintillation Counter Characterization, Optimization and Benzene Purity Correction
Authors: McCormac F. G.
Published: July 2016

In liquid scintillation counting (LSC), small variations in benzene purity can cause 14C pulse-height spectra to move with respect to the counting window. Thus, one must carefully monitor the purity of each benzene sample and apply corrections for spectral shifts. I describe here the techniques used at Queen's University Belfast for deriving correction factors for observed small variations in benzene purity. I also describe the methods used at our laboratory to fine-tune our Quantulus LS counters for high-precision dating. The tuning of the instruments minimizes the effect of fluctuations in gain that may occur during the long counting periods required for high-precision dating. Any remaining influences on efficiency owing to gain changes are corrected for, along with the purity correction, by continuous monitoring of the spectrum produced by the external source.
A Tandem Mass-Spectrometric Method of Cosmogenic Isotope Analysis
Authors: Pavlov A. K. , Kogan V. T. , Gladkov G. Y.
Published: July 2016

We propose an original method for analysis of low-concentrations of stable and long-lived radioactive nuclides. We discuss the parameters of the main features of the “Trace” spectrometer (a multicharged-ion laser source, a highly sensitive time-of-flight mass spectrometer, a charge-exchange chamber and a mass spectrometer for positive and negative single-charged ion analysis). We also compare these features with conventional AMS devices.
High-Precision Bidecadal Calibration of the Radiocarbon Time Scale, 500–2500 BC
Authors: Pearson Gordon W. , Stuiver Minze
Published: July 2016

The sole purpose of this paper is to present a previously published 14C data set to which minor corrections have been applied. All basic information previously given is still applicable (Pearson & Stuiver 1986). The corrections are needed because 14C count-rate influences (radon decay in Seattle, a re-evaluation of the corrections applied for efficiency variation with time previously unrecognized in Belfast) had to be accounted for in more detail. Information on the radon correction is given in Stuiver and Becker (1993). The Belfast corrections were necessary because the original correction for efficiency variations with time was calculated using two suspect standards (these were shown to be suspect by recent observations) that overweighted the correction. A re-evaluation (Pearson & Qua 1993) now shows it to be almost insignificant, and the corrected dates (using the new correction) became older by about 16 years.
Pretoria Calibration Curve for Short-Lived Samples, 1930–3350 BC
Authors: Vogel J. C. , Fuls AnneMarie , Visser Ebbie , Becker Bernd
Published: July 2016

The high-precision radiocarbon calibration curve for short-lived samples (1–4 yr) of the early historical period (3rd millennium BC) presented previously (Vogel et al. 1986) has been further substantiated and extended to link with a similar curve produced by de Jong for part of the 4th millennium BC (de Jong & Mook 1980). The precise dendrochronological age of the sample set measured by de Jong has finally been fixed (de Jong, Mook & Becker 1989), so that the two sets now cover the period 1930–3900 BC, i.e., the Early Bronze Age and Late Chalcolithic periods of the Middle East. The standard calibration curve for the two sets is presented by Vogel and van der Plicht (1993).
An 11,000-Year German Oak and Pine Dendrochronology for Radiocarbon Calibration
Authors: Becker Bernd
Published: July 2016

Sequences of dendrodated tree rings provide ideal sources for radiocarbon calibration. The wood structure of trees consists of continuous series of annual growth layers, the carbon content of which can be 14C-dated and calibrated to calendar yr. The cellulose and lignin of trees deposited in river gravels or peat-bog sediments below the water table are often very well preserved, even after several millennia. Such tree-trunk deposits are well protected from contamination by younger or older organic materials. Further, the physical and chemical structure of wood allows a strong chemical pretreatment of samples for 14C analysis.
How Smooth Should Curves Be for Calibrating Radiocarbon Ages?
Authors: Törnqvist Torbjörn E. , Bierkens Marc F. P.
Published: July 2016

We show that smoothed versions of the high-resolution calibration curve should be used when 14C ages are calibrated with large (> ∼30 14C yr) measurement errors (represented by standard deviation δm) or are mixtures of elements of variable age (natural sample error with standard deviation δn). The degree of smoothing should agree with the standard deviation of total sample error, δt, the square root of the quadratic sum of δm and δn. However, in most cases, δt is not well known, especially due to difficulties in quantifying δn. We present an inverse method that gives a measure of mean δt, for different materials that are widely used in (conventional) 14C dating. Calculations with large (>100) data sets of wood, charcoal, ombrotrophic peat and minerotrophic peat/gyttja samples indicate that δt of such materials is generally much larger than previously assumed, mainly because of large values of δn. This means that particularly in organic deposits, strongly smoothed calibration curves should be used where medium-term 14C variations (wiggles) are completely straightened. This has especially major consequences for calibrating 14C histograms for natural 14C variations. We conclude that 14C histograms consisting of samples of organic deposits do not require correction for medium-term 14C variations and that uncalibrated 14C histograms need not be as suspect as is usually believed.
Small Sample Dating in China
Authors: Zhou Weijian , Head M. J. , Kaihola Lauri
Published: July 2016

The Xi'an Laboratory of Loess and Quaternary Geology has developed a small sample 14C dating facility consisting of a Wallac 1220 Quantulus™ liquid scintillation spectrometer, and a miniature benzene synthesis line based on the synthesis procedures used at the Australian National University (ANU). This line can produce ca. 0.3-ml benzene samples, which are then measured for 14C activity using 0.3-ml Teflon vials developed by Wallac Oy. The counting performance of the Quantulus™ spectrometer using 0.3-ml vials has been evaluated, and a potential age limit of ca. 45,000 BP has been obtained for samples containing up to 250 mg carbon. This dating facility fills the gap between large sample (2.4–6 g carbon) and microsample (<1 mg carbon) handling to form a 14C dating method sequence.
The Chronology of Coastal Morphogenesis and Human Settlement on Aitutaki, Southern Cook Islands, Polynesia
Authors: Allen Melinda S.
Published: July 2016

Twenty-seven 14C determinations from Aitutaki, southern Cook Islands inform on human settlement and Holocene coastal processes. I examine sedimentary, radiometric and archaeological data from Aitutaki with reference to regional evidence for a minor Holocene sea-level regression, which are in general agreement. Related processes of shoreline progradation and aggradation created near-shore environments conducive to human habitation, directly evidenced by ca. AD 900–1200. Nevertheless, biotic materials associated with this early cultural stratum suggest human colonization prior to this time. Archaeological preservation and recovery also may have been affected by changing sea level and related sedimentary processes.
ANU Radiocarbon Date List XI: Radiocarbon Dates from Lakes Barrine and Eacham, Atherton Tableland, North Queensland, Australia
Authors: Head M. J. , Taylor L. J. , Walker D.
Published: July 2016

Lakes Barrine and Eacham and their small, discrete, forested catchments are sites of intensive sedimentological, palynological and ecological research. The studies that we present here concentrate on integrating population statistics of tree species of the living forest with their histories, as documented by fine-resolution pollen analysis (Green and Dolman 1988). Most of the work has been undertaken at Lake Barrine, where the last 5 ka is recorded in laminated sediments. Additional information about these sites and about aspects of the project is contained in Chen (1986, 1987, 1988), Goodfield (1988), Grindrod (1979), Timms (1976, 1979) and Walker (1988).
British Museum Natural Radiocarbon Measurements XXIII
Authors: Ambers Janet , Bowman Sheridan
Published: July 2016

The following list consists of dates for archaeological samples measured mostly between October 1989 and November 1990. Charcoal and grain samples were pretreated with 1M HC1 followed by washing in water and, in the majority of cases, with dilute alkali for the removal of humic acids. Wood samples were treated in the same way, or, if large enough, reduced to cellulose with chlorine dioxide produced in situ. Antler and bone samples were treated with cold dilute acid. We use the term “collagen” to mean the acid-insoluble organic fraction produced by this treatment rather than the true biochemical definition.
Human Settlements and the Last Deglaciation in the French Alps
Authors: Evin Jacques , Bintz Pierre , Monjuvent Guy
Published: July 2016

According to most geological and geomorphological studies, the maximal advance of the Würmian glaciers in the French Alps occurred at least before 40 ka bp and cannot be dated by 14C. Scientists believed that this dating method could be used for dating the last glacial advance and late deglaciation in the region. The scarce and scattered 14C dating results available from geological samples do not confirm an early (ca. 18 or 20 ka bp) age for the total cooling of the ice nor do they prove that residual ice sheets remained at low elevations. Attempting to solve this chronological problem, we compiled current archaeological knowledge of the oldest Late Paleolithic sites. A review of their 14C results shows that no site older than 15 ka bp (with Gravettian, Solutrean or early Magdalenian industries) can be found east of the Saône-Rhône Valley, even at low elevations. Only rare sites, dated to ca. 14.5 ka bp, may be found close to the mountain regions that were suddenly occupied around the beginning of the Bølling period (ca. 13.5 ka bp). Thus, it seems that the eastern Alps offer no evidence for direct association between glacial retreat and human settlement or simultaneous occurrence in early or late deglaciated areas.
A Note on Calibration Curves
Authors: van der Plicht J. , McCormac F. G.
Published: July 2016

Following the 12th International Radiocarbon Conference in Trondheim, a special calibration issue was published (Stuiver and Kra 1986) carrying a bidecadal calibration curve from 1950 cal ad–2500 cal bc (Stuiver and Pearson 1986; Pearson and Stuiver 1986) that was recommended at the conference (Mook 1986).
The Use of Carbon Isotopes (13C,14C) in Soil to Evaluate Vegetation Changes During the Holocene in Central Brazil
Authors: Pessenda L. C. R. , Aravena Ramon , Melfi A. J. , Telles E. C. C. , Boulet René , Valencia E. P. E. , Tomazello Mario
Published: July 2016

This paper presents carbon isotope data measured in three soil profiles from the Salitre area, Central Brazil. The study forms part of a research project on tropical and subtropical soils in Brazil, in which the main objective is to use carbon isotopes to provide information about vegetation changes that have occurred in relation to climate changes during the Holocene.14C data from charcoal samples and soil organic matter (SOM) indicate that the organic matter in the soils studied is of Holocene age at least. Furthermore, the presence of a significant amount of charcoal in the soils suggests that forest fire was a significant ocurrence during the Holocene and probably had an important role in determining the dynamics of forest vegetation in the study area. Correspondingly,13C data indicate that C3plants provided the dominant vegetation of the study area, even during the dry periods when savanna vegetation is supposed to have replaced the forest communities. This study contributes to our better understanding of the relation between climatic changes and vegetation in the subtropical region of Brazil.
14C Dating and Soil Organic Matter Dynamics in Arctic and Subarctic Ecosystems
Authors: Cherkinsky A. E.
Published: July 2016

The carbon content, pH and 14C concentration of humic acids were determined for three soil series of Arctic and Subarctic ecosystems. The measured 14C ages were interpreted in the light of an equilibrium model of humus formation and of mineralization processes in recent soils, and the coefficient of renovation, Kr, was calculated for humic acids. The comparison of Kr for series formed under different climatic conditions suggested that global warming could accelerate decomposition of soil organic matter and possibly increase productivity of ecosystems of the Arctic region.
Hamburg Radiocarbon Thin Layer Soils Database
Authors: Becker-Heidmann Peter , Scharpenseel Hans-Wilhelm , Wiechmann Horst
Published: July 2016

We report here the remainder of the Hamburg University dates on thin soil layers (HAM 1652–3129).
Evaluation of Wood Pretreatments on Oak and Cedar
Authors: Hoper S. T. , McCormac F. G. , Hogg A. G. , Higham T. F. G. , Head M. J.
Published: July 2016

In a separate study, we conducted a series of high-precision radiocarbon measurements using wood from Britain and New Zealand to investigate interhemispheric offsets and possible temporal variations. To minimize variability associated with different species, the pretreatment of the oak (Quercus patraea) and cedar (Librocedrus bidwilli) was to α-cellulose for both. This study investigates the thoroughness of a range of pretreatment processes by the stable isotope analysis of the products.