bluuebunny/crossref_metadata_2025 huggingface dataset:
US Geological Survey, Menlo Park, California, Radiocarbon Measurements I
Authors: Robinson Stephen W
Published: July 2016

A radiocarbon laboratory at the US Geological Survey Western Regional Headquarters in Menlo Park, California was established in temporary rooms in March, 1976. In August, 1976 the laboratory was dismantled and moved into a new building that was designed specifically for the facility. This list contains results of operations in the temporary laboratory, which was located in the basement of a two-story building. The counter shield was 15cm lead and 5cm borated paraffin with an additional 5cm of lead above the counters. The anticoincidence ring consisted of copper tubes, 5cm in diameter, mounted around a copper tube with an inside diameter of 15cm. Installed in the anticoincidence ring were the four sample counters, whose characteristics are shown in Table 1. The counting electronics unit, which is designed to service five sample counters, follows the design of Gulliksen (1972) in most respects. The sample counters were constructed of copper and quartz; their design is described in detail by Robinson (1977). The CO2 counting gas was purified by recirculation over copper and silver at ca 450°C. Wood samples were typically pretreated by leaching for 24 hours alternately in 1N sodium hydroxide and hydrochloric acid solutions at 70°C.
Trondheim Natural Radiocarbon Measurements VIII
Authors: Gulliksen Steinar , Nydal Reidar , Skogseth Fred
Published: July 2016

Most dates in this list were obtained between 1972 and 1976. Treatment of samples has remained essentially the same as described previously (R, 1975, p 364).
US Geological Survey Radiocarbon Dates XIII
Authors: Spiker Elliott , Kelley Lea , Rubin Meyer
Published: July 2016

This list contains the results of some measurements made between 1965 and 1973. Samples are counted in the form of acetylene gas, as previously, and ages computed on the basis of the Libby half-life, 5568 ± 30 years. The dates have not been corrected for fractionation by a δ13C measurement. The error listed, always larger than the one-sigma statistical counting error commonly used, takes into account possible fractionation in the laboratory and in nature and the variability experienced with replicate samples. We wish to thank Charles Oman for his technical assistance.
US Geological Survey, Reston, Virginia, Radiocarbon Dates XIV
Authors: Kelley Lea , Spiker Elliott , Rubin Meyer
Published: July 2016

This list contains the results of some measurements made between 1966 and 1975, and includes some earlier unpublished dates. Samples are counted in the form of acetylene gas, as previously, and ages computed on the basis of the Libby half-life, 5568 ± 30 years. The dates have not been corrected for fractionation by making a 13C measurement. The error listed, always larger than the one-sigma statistical counting error commonly used, takes into account possible fractionation in the laboratory and in nature and variability experienced with replicate samples. We thank Linda Wilt for helping in the preparation of the manuscript and Charles Oman for his technical assistance.
The Quaternary Isotope Laboratory Thermal Diffusion Enrichment System: Description and Performance
Authors: Grootes Pieter M , Stuiver Minze
Published: July 2016

The thermal diffusion enrichment system of the Quaternary Isotope Laboratory consists of 23 hot wire columns of 3m effective length combined to 2 separate systems of 3 and 3 separate systems of 4 columns at the top, each system in series with 1 bottom column. From ≈ 130 L NTP of CO (∼ 65g of carbon) it produces ≈ 8 L NTP of CO (~ 4g of carbon) enriched in12C18O by a factor 6 to 7 and in14C16O by a factor 7 to 8 in about 5 weeks. For12C18O the system has a theoretical equilibrium separation factor of about 250 and a theoretical equilibrium enrichment of about 15. For14C16O these values are 1300 and 16, respectively. The dependence of thermal diffusion transport on gas exchange between top and bottom section and between columns and reservoirs and on wire temperature is given. Forced gas exchange and a higher wire temperature gave a more rapidly increasing enrichment without substantially increasing its final value of 6 to 7 for12C18O. A comparison with the Groningen enrichment system shows that the two systems behave very similarly and that not the system geometry but individual column parameters and the ratio total sample mass/enriched sample mass are the dominant factors determining the enrichment.
Vienna Radium Institute Radiocarbon Dates IX
Authors: Felber Heinz
Published: July 2016

Measurements have continued with the same proportional counter system, pretreatment procdure, methane preparation, measurement, and calculation, as described previously (R, 1970, v 12, p 298-318). Uncertainties quoted are single standard deviations originating from standard, sample, background counting rates and half-life. No 13C/12C ratios were measured.
ANU Radiocarbon Date List VII
Authors: Polach H A , Thom B G , Bowman G M , Wilkie Stella
Published: July 2016

Along SE coast of Australia a variety of Holocene barriers composed of siliceous sand and shell detritus occur within bedrock-confined embayments. On basis of morphostratigraphy 4 barrier types are recognized: prograded, stationary, receded and episodic transgressive dunes. Several subtypes are also distinguished. Composite bay barriers involving partial eolian reworking of a prograded barrier constitute most complex examples of Holocene depositional sequences on this coast. The present list is a preliminary attempt at defining the age structure of a group of such barriers (excepting receded type). Ages are reported inconventional yearsbp. Text references to ages and age ranges areenvironmental effect correctedages bp*and yr*(as recommended by Stuiver and Polach, 1977), using 450 ± 35 yr as postulated by Gillespie and Polach (in press) in order to relate Australian oceanic environment shells to terrestrial environment wood. δ13C errors, where based on measurement, are always ± 0.2% and are not shown in the text; when based on estimated values (Est) the error is given.
Florence Radiocarbon Dates IV
Authors: Azzi C M , Gulisano F
Published: July 2016

This list comprises age measurements carried out from May 1977 to July 1978. Nearly all the samples are of prehistoric and archaeologic interest. All samples are from Italian territory.
Birbal Sahni Institute Radiocarbon Measurements II
Authors: Rajagopalan G , Mittre Vishnu , Sekar B
Published: July 2016

The radiocarbon dates covered in this list were measured during 1978. Chemical and counting procedures are as reported previously (R, 1978, v 20, p 398-404). Age calculations are based on the conventional 14C half-life (5570 yr) and on the contemporary value of 95% of the activity of NBS oxalic acid. Errors quoted correspond to 1σ value which takes into account the counting statistics, the uncertainty in the half-life, and the instability of the counting system. The ages are not corrected for isotopic fractionation in nature.
Köln Radiocarbon Measurements II
Authors: Freundlich J C , Schwabedissen H , Wendt W E
Published: July 2016

Since the publication of our first date list (R, 1966, v 8, p 239-247), our 14C laboratory has produced about 1500 radiocarbon dates, including several hundreds of concordant double determinations, the majority of which were on archaeologic samples. The greater part of the other dates concerned dendrochronologic samples from our Tree Ring Laboratory (Schmidt, 1977; Freundlich, 1977). Several archaeologic dates have already been published in articles on archaeology, preferentially by the respective excavators, in a few instances also by us (eg, Schwabedissen and Freundlich, 1968; Faruggia et al, 1973; Kuper, 1975; Lüning and Zürn, 1977; Hohenschwert, 1978). An extensive compilation of Neolithic dates is in preparation.
Tallinn Radiocarbon Dates VI
Authors: Punning J M , Rajamäe R , Joers K , Putnik H
Published: July 2016

The following list includes samples dated at the Institute of Geology, Academy of Sciences of the Estonian SSR in 1978. The measurement of natural 14C activity is performed by 1-channel and 2-channel scintillation devices (Punning & Rajamäe, 1977). Ages are calculated using the half-life of 5568 ± 30 years and 0.95 NBS oxalic acid modern standard with ad 1950 as reference year.
University of Waterloo Radiocarbon Dates I
Authors: Berry Jeanne C , Drimmie Robert J
Published: July 2016

The radiocarbon dating laboratory is part of the Department of Earth Sciences, University of Waterloo. The natural level radio-isotope facility, built in the spring of 1974, was built primarily for dating groundwater and a combustion line for organic samples was added in 1975.
Gliwice Radiocarbon Dates VIII
Authors: Pazdur Mieczysław F , Awsiuk Romuald , Bluszcz Andrzej , Pazdur Anna , Walanus Adam , Zastawny Andrzej
Published: July 2016

The following list sums up the results of radiocarbon dating of geologic samples obtained mostly during 1978 and 1979. Measurements have continued with the same proportional counters, pretreatment procedures, carbon dioxide purification, measurement and calculation as described previously (Pazdur et al, 1982). Ages are reported as conventional radiocarbon dates in years before ad 1950. No corrections for 13C/12C ratio were made for samples reported in this date list. Infinite dates are based on a 2-sigma criterion (Pazdur and Walanus, 1979). Sample descriptions and comments are based on information provided by the submitters.
British Museum Natural Radiocarbon Measurements XIV
Authors: Burleigh Richard , Matthews Keith , Ambers Janet
Published: July 2016

The following list consists of dates for archaeologic and some geologic samples, mostly measured from January 1978 to December 1979. The dates were obtained by liquid scintillation counting of benzene using the laboratory procedures outlined in previous lists (see, eg, BM-VIII, R, 1976, v 18, p 16). The dates are expressed in radiocarbon years relative to ad 1950 based on the Libby half-life for14C of 5570 yr, and are corrected for isotopic fractionation (δ13C values are relative to PDB). No corrections have been made for natural14C variations. The modern reference standard is NBS oxalic acid (SRM 4990). Errors quoted with the dates are based on counting statistics alone and are equivalent to ± 1 standard deviation (± 1σ). Dates in this list reported to submitters or published elsewhere before the introduction of the new guidelines for rounding of computed figures have deliberately been left unrounded. From BM-XV onwards all BM dates will be rounded before publication in conformity with the recently recommended procedures (R, 1977, v 19, p 362). Descriptions, comments, and references to publications are based on information supplied by submitters.
University of Wisconsin Radiocarbon Dates XX
Authors: Steventon Raymond L , Kutzbach John E
Published: July 2016

Procedures and equipment have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH–Na4P2O7 and dilute H3PO4 before conversion to the counting gas methane; marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCl for 15 minutes, then dilute NaOH–Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCl, NaOH–Na4P2O7, and then dilute HCl again.
Atmospheric Radiocarbon: Implications for the Geomagnetic Dipole Moment
Authors: Sternberg R S , Damon P E
Published: July 2016

The geomagnetic field is one of the major physical fields of the earth. Because its source is fluid motion in the outer core, it exhibits temporal changes, called secular variation, which are quite rapid compared to most geologic phenomena. The prehistoric secular variation is usually inferred from paleomagnetic data. We will discuss here how changes in the atmospheric 14C content can be used to gain additional insight into the behavior of the dipole moment over the past 8500 years. By rewriting the differential equations representing the 14C geochemical cycle in finite-difference form, we are able to convert the atmospheric 14C activity record into an equivalent radiocarbon dipole moment.
Mid-Wisconsinan Radiocarbon Dates from Mastodon- and Mammoth-Bearing Springs, Ozark Highland, Missouri
Authors: Haynes C V , Stuiver Minze , Haas Herbert , King J E , King F B , Saunders J J
Published: July 2016

From 1966 to 1979, the University of Missouri, the University of Arizona, and the Illinois State Museum conducted extensive interdisciplinary investigations of Late Pleistocene peat deposits associated with springs, some extinct, in the Pomme de Terre River Valley of the Ozark Highland, Missouri (fig 1). Most of the sites are now beneath the waters of the Harry S Truman reservoir. Archaeologic investigations in the area produced a remarkably long sequence of cultural change and development during the Holocene but produced no evidence of human presence in the area prior to 11,000 years ago despite diligent excavation of favorable bone-bearing deposits.
Radiocarbon Dating of Tufa in Paleoclimatic Studies
Authors: Srdoč Dušan , Horvatinčić Nada , Obelić Bogomil , Sliepčević Adela
Published: July 2016

Calcareous deposits known as tufa or travertine contain biogenic carbon and are a potential source of geochronologic information. Many dated samples from Karstic regions in Yugoslavia proved that 14C analyses of tufa can provide reliable data reflecting climatic conditions in the past. Systematic dating of tufa samples revealed two distinct groups of deposits: recent tufa deposits, with a sharp age limit of ∼6000 ± 500 years BP, and old tufa deposits with 14C age ranges from 25,000 ± 2300 years BP to the lowest limit of our 14C dating system (∼37,000 years). A histogram based on the initial activity AO = 0.85 shows the age distribution of randomly sampled tufas vs sample frequency. A time gap between ∼6000 BP and ∼23,000 BP is evident, reflecting cooler climatic conditions. The start of peat deposition is coincident with that of tufa growth in the Holocene.

Paleoclimatic implications of tufa growth periods obtained by 14C dating are as follows: climatic conditions that favor tufa formation at least in karstic regions, are very stringent. Therefore, climatic conditions, such as mean annual temperature and humidity, as well as hydrologic and vegetational conditions, must have been very similar in periods of tufa growth. While recent tufa deposits are coincident with the warm Holocene period, old tufa can be associated with warm interstadials in the Würm.
Radiocarbon Dating Archaeologic and Environmental Samples Containing 10 to 120 Milligrams of Carbon
Authors: Sheppard John C , Hopper J Fred , Welter Yvonne
Published: July 2016

A conventional 14C system with either a 15cm3 or a 100cm3 methane gas proportional counting tube, each constructed from high purity copper, has been used at the Washington State University 14C laboratory for three years (Sheppard, Hopper, Westberg, 1981). The electronic components of this system included highly stable (John Fluke) power supplies, modified pre-amplifiers (Canberra), and NIM amplifiers, single channel analyzers, scalers, timers, etc, (ORTEC). Modules were selected for a highly stable low-noise system. The system was designed to minimize problems generated by ground-loops, electromagnetic noise pick-up, and line noise. It operates in a copper-lined basement room of a four-story brick and concrete building along with a second and older gas proportional system which has three 500cm3 copper counting tubes operated at 2 or 3 atmospheres of methane. Analysis of the older system's background data indicates that the background counting rate of 0.8 counts per minute is virtually independent of atmospheric pressure. It has not been possible to determine the pressure dependence of the small counting tubes.
An International Reference Material for Radiocarbon Dating
Authors: Mann W B
Published: July 2016

In August 1980, the National Bureau of Standards (NBS) issued, in the form of oxalic acid, a new International Reference Material of contemporary 14C for use in radiocarbon dating laboratories. This reference material was to replace the 1975 oxalic-acid standard, supplies of which had been practically exhausted in 1978. The preparation of the new oxalic-acid standard was described in a preliminary report, as were, also, the results then available for the activity-concentration ratio of the new to the old standard obtained by a number of leading international laboratories.

With the recent completion of the analysis of all results submitted by the participating laboratories, NBS plans to issue these recently calibrated samples of oxalic acid as an NBS Standard Reference Material. There is, however, no significant difference in the reported value of its activity concentration, relative to that of the 1957 standard, from that given provisionally in 1980.

Subsequent to our report (Cavallo and Mann, 1980) a further measurement of relative activity concentration was reported by the Radiocarbon Laboratory of Peking University. Their value, and that also for δ13C, is insignificantly different from the average value of the results submitted by the eleven laboratories that participated in the international comparison organized by NBS.
A Secondary Standard for Radiocarbon Dating
Authors: Angiolini Fernando E , Albero Miguel C
Published: July 2016

The preparation and calibration of a secondary standard for the INGEIS Radiocarbon Dating Laboratory are presented. This standard is barium carbonate with a specific activity almost twice that of NBS oxalic acid. It was prepared from BaCO3 with high specific activity and commercial potassium carbonate by an isotopic dilution technique. The advantages of this standard are: 1) the preparation is simple and can be achieved with ordinary labware; 2) the production of CO2 by acid attack from this carbonate shows minimum isotopic fractionation. At least, it has less fractionation than wet oxidation of oxalic acid, the problems of which are described in the literature. This standard ensures better reproducibility in activity measurements; 3) despite some problems of activity exchange with atmospheric CO2 concerning carbonates, measurements of activity over a period of about two years have shown no significant deviation from the mean value. A tentative explanation of this phenomenon is also given. The activity ratio between BaCO3 and NBS oxalic acid is given with its error, and the statistical tests used in the calibration are briefly explained. Finally, a control chart for the activity of the standard over a long period is drawn, showing non-significant deviation and supporting the usefulness of this standard.
Time History of Human Gallstones: Application of the Post-Bomb Radiocarbon Signal
Authors: Druffel Ellen M , Mok Henry Y I
Published: July 2016

Bomb-produced14C is a valuable tool for studying rates of short-term processes involving carbon cycling. This study shows that bomb14C is an excellent tracer of a biochemical process that takes place in the human body, namely the accretion of stones in the gallbladder. The methods developed for obtaining time histories of14C/12C and13C/12C in concentric layers from a large gallstone (30mm diameter) are reported. Formation times are assigned by matching the14C/12C obtained from individual layers with those found for known-aged tree rings. Results show that the gallstone grew over a period of 10 years and seems to have lain dormant within the gallbladder for a period of 11 years. The average growth rate was 1.5mm/year.
The Integration of Radiocarbon Dating in Archaeology
Authors: Waterbolk H T
Published: July 2016

In the past 30 years many hundreds of archaeologic samples have been dated by radiocarbon laboratories. Yet, one cannot say that 14C dating is fully integrated into archaeology. For many archaeologists, a 14C date is an outside expertise, for which they are grateful, when it provides the answer to an otherwise insoluble chronologic problem and when it falls within the expected time range. But if a 14C date contradicts other chronologic evidence, they often find the ‘solution’ inexplicable. Some archaeologists are so impressed by the new method, that they neglect the other evidence; others simply reject problematic 14C dates as archaeologically unacceptable. Frequently, excavation reports are provided with an appendix listing the relevant 14C dates with little or no discussion of their implication. It is rare, indeed, to see in archaeologic reports a careful weighing of the various types of chronologic evidence. Yet, this is precisely what the archaeologist is accustomed to do with the evidence from his traditional methods for building up a chronology: typology and stratigraphy. Why should he not be able to include radiocarbon dates in the same way in his considerations?
Database Management Systems, Radiocarbon and Archaeology
Authors: Moffett J C , Webb R E
Published: July 2016

An annotated card index of 14C dates directly relating to Old World cultural material of Palaeolithic and Mesolithic age (> 50,000 − ∼7000 BP) and New World material older than 7000 BP was compiled in 1972 to include all previously published dates. It is updated annually and currently correct to the end of 1981. The need for such an index to reduce duplication of research time spent in primary data acquisition has long been implicity recognized. Indeed, many such data files may already exist. We wish to discover the nature, scope, and intercompatibility of other lists both to improve our own system and to allow for an exchange of information without unnecessary duplication. Our sources include SCIENCE and NATURE but RADIOCARBON is the major source of information. The general scientific and archaeologic literature has not been systematically searched. Where possible, other published lists have been consulted and additional dates incorporated in our list.
Current 14C Measurements with the University of Washington FN Tandem Accelerator
Authors: Farwell G W , Grootes P M , Leach D D , Schmidt F H , Stuiver Minze
Published: July 2016

Our accelerator mass spectrometry (AMS) system shows a one-to-one relationship between sample 14C concentrations determined by AMS - and by β-counting. Measurements of unknown samples against a standard indicate that 14C concentration measurements to better than 2% can be made. For a 30-second data collection interval in a typical run of 100 intervals, the variability of the beam injected into the accelerator is ca 2%, that of the machine transmission is ca 4%, and counting statistics give 4.7% standard deviation for a sample of 80% of modern carbon.
Radiocarbon Dating with the Utrecht Tandem Accelerator
Authors: van der Borg K , Hoogenboom J A , Jelmersma R A , Vermeer Abraham , Hut Gert
Published: July 2016

In 1979 when accelerator mass spectrometry was started in the Netherlands, Gove (1978) and Litherland (1980) demonstrated that a tandem accelerator is eminently suited for this work. Isotope ratios below 10−15 could be determined and applications were stimulated on numerous fields of research. 14C dating in particular would become an important application because smaller samples could be employed and more complex dating problems could be attacked. However, the 5% accuracy reached at that time had to be improved towards the 0.5% obtained with the conventional method of counting decays. Purser and Hanley (1978) pointed out that this high accuracy could be reached in facilities especially dedicated to dating. Rapid switching between measurements on different isotopes turned out to be crucial (Suter et al, 1981). We decided to proceed in two phases. In the first phase, the existing EN-tandem facility would be used as before and modified for the detection of 14C ions. From measurements with 14C ions from different samples, information would be obtained about the limitations of the existing facility. In the second phase, this information would be used to develop a facility in which accurate measurements of isotope ratios can be performed for elements throughout the periodic system. Conventional 14C dating will be extended in collaboration with the Isotope Physics Laboratory in Groningen. Also, applications with other elements will be studied. The improved facility is scheduled for operation in the spring of 1983.
Moscow MV Lomonosov State University Radiocarbon Dates II: Sea Level Indicators from Coastal USSR
Authors: Glushankova N I , Parunin O B , Selivanov A O , Shlukov A I , Timashkova T A
Published: July 2016

The following list summarizes the post-1970 laboratory results of 14C dating of ancient sea-level indicators from the coasts of the Soviet Union. One of the aims of the International Geologic Correlation Programme Project No. 61 “Sea level movements during the last deglacial hemicycle” is the global cataloguing and mapping of ancient sea levels. The laboratory, which acts as the USSR National curator for these age measurements obtains dates sampled from its own expeditions and from other institutions of the country.
Selective Leaching of Shells for 14C Dating
Authors: Vita-Finzi Claudio , Roberts Neil
Published: July 2016

Although acid leaching of shell carbonates prior to 14C assay is usually desirable, under some circumstances it can worsen contamination by preferentially dissolving unaltered shell and thus increasing the proportion of secondary carbonate. The risk can be eliminated by monitoring the progress of leaching with the help of microscopy and x-ray diffraction.
University of Wisconsin Radiocarbon Dates XXI
Authors: Steventon Raymond L , Kutzbach John E
Published: July 2016

Procedures and equipment used in the University of Wisconsin laboratory have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH-Na4P2O7 and dilute H3PO4 before conversion to the counting gas methane; marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCl for 15 minutes, then dilute NaOH-Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCl, NaOH-Na4P2O7, and then dilute HCl again.
Institut Royal du Patrimoine Artistique Radiocarbon Dates X
Authors: Dauchot-Dehon Michèle , Van Strydonck Mark , Heylen Jos
Published: July 2016

This list contains the results of 14C determinations obtained at the laboratory in 1982–1983.
Compilation of Isotopic Dates from Antarctica
Authors: Stuiver Minze , Braziunas Thomas F.
Published: July 2016

This compilation of radiometric data from Antarctica contains abstracted information from 400 publications, resulting in nearly 2500 separate entries. Each entry, or “date listing”, gives basic information of the sample site as well as the dating method and the age(s) of the sample analysed. The date list differs from those routinely published in Radiocarbon because we included not only radiocarbon but all dating methods.
INGEIS Radiocarbon Laboratory Dates II
Authors: Albero Miguel C , Angiolini Fernando E
Published: July 2016

The following list consists of archaeologic and geologic dates from Argentina processed in the 14C laboratory of INGEIS. The ages presented were obtained by liquid scintillation counting of benzene, using the techniques outlined in a previous paper (Albero & Angiolini, 1983). The results are expressed in 14C years relative to 1950, using the Libby half-life of 5570 yr.
Measurement of 10Be and 26Al with a Tandetron Accelerator Mass Spectrometer Facility
Authors: Yiou Françoise , Raisbeck Grant , Bourles Didier , Lestringuez Jacques , Deboffle Dominique
Published: July 2016

A description is given of the use of a Tandetron accelerator mass spectrometer system for measuring the isotopes 10Be and 26Al.
Radiocarbon Dating with the University of Washington Accelerator Mass Spectrometry System
Authors: Grootes Pieter M , Stuiver Minze , Farwell George W , Leach Donald D , Schmidt Fred H
Published: July 2016

The University of Washington FN tandem accelerator mass spectrometry (AMS) system has been used in a series of 14C studies. 1) The 14C concentrations in annual growth rings for 1962, 1963, and 1964 of a Sitka spruce, each divided into ten sequential segments, were measured; a full and rapid response of tree-ring cellulose to atmospheric changes in 14CO2 is indicated, with a delay, if any, of not more than three weeks. 2) The C concentrations in two chemical fractions of dissolved organic carbon and in two fractions (by size) of particulate organic carbon were measured for Amazon River samples from several locations. All contain bomb carbon, but the amounts differ significantly. 3) Algae samples from lakes in the dry valleys of Antarctica were dated in order to assist in the reconstruction of the climatic history of Antarctica. 4) Background studies indicate that the contribution of the AMS system itself to the observed 14C concentrations is equivalent to an age of ca 60,000 14C yr BP; for a prepared sample of 5mg of carbon the background corresponds to ca 50,000 years.
Thin Layer δ13C and D14C Monitoring of “Lessive” Soil Profiles
Authors: Becker-Heidmann Peter , Scharpenseel Hans-Wilhelm
Published: July 2016

The natural 14C and 13C content of soil organic matter and their dependence on depth for two Alfisols are presented. This soil type which covers a large area of the earth's surface is characterized by clay migration processes (“Lessivé”). The samples were taken as successive horizontal layers of 2cm depth from an area of ca lm2 size as deep as the C content allows 14C analysis. The minima of the D14C distribution decrease with depth, while the maxima increase in the upper, leached horizon (A1) due to bomb 14C and decrease in the lower, clay illuviated (Bt). δ13C indicates proceeding decomposition in A1 and protection of carbon, probably due to the formation of clay humus complexes in Bt. δ13C values were also used for age correction of the 14C data due to isotopic fractionation. The D14C and δ13C depth distributions are characterized by sharp peaks at the boundaries of the horizons, probably caused by the influence of textural changes on the transport of C with percolating water.
Radiocarbon in Particulate Matter from the Eastern Sub-Arctic Pacific Ocean: Evidence of a Source of Terrestrial Carbon to the Deep Sea
Authors: Druffel Ellen R M , Honjo Susumu , Griffin Sheila , Wong C S
Published: July 2016

Carbon isotope ratios were measured in organic and inorganic carbon of settling particulate matter collected with a sediment trap at Ocean Station “P” in the Gulf of Alaska from March to October, 1983. Dissolved inorganic carbon (DIG) in surface sea water collected during two different seasons in 1984 were analyzed using large gas proportional counters and revealed a minimum seasonal Δ14C variation of 14‰. Results show that the Δ14C of calcium carbonate scdimenting to the deep sea is the same as that measured in surface water DIC. In contrast, particulate organic carbon (POC) had significantly higher Δ14C values (by 25–70‰) than that in surface water DIC. Also, the δ13C of the POC was markedly lower than previously reported values from other trap stations and marine particulate matter in general. Results from this study suggest that a significant amount of the POC settling to the deep sea at this pelagic station is of terrestrial origin, not strictly of marine origin as had previously been believed.
AMS Radiocarbon Dates on Foraminifera from Deep Sea Sediments
Authors: Andree Michael , Oeschger Hans , Broecker W S , Beavan Nancy , Mix Alan , Bonani Georges , Hofmann H J , Morenzoni Elvezio , Nessi Marzio , Suter Martin , Wölfli Willy
Published: July 2016

14C ages were determined on samples of foraminifera separated from cores from three areas of the tropical Pacific (East Pacific Rise, Oontong Java Plateau, and South China Sea). Analyses were made on four planktonic species and on mixed benthics. The purpose of the multiple analysis on planktonic species is to assess the importance of artifacts resulting from the bioturbation-abundance change couple, from the bioturbation-partial dissolution couple and from redeposition by bottom currents. The goal is to use the benthic-planktonic age difference as a means of establishing changes in deep sea ventilation rate over the past 25,000 years. Results of a part of this work are presented in this paper.
Dating of Holocene Stratigraphy with Soluble and Insoluble Organic Fractions at the Lubbock Lake Archaeological Site, Texas: An Ideal Case Study
Authors: Haas Herbert , Holliday Vance , Stuckenrath Robert
Published: July 2016

The Lubbock Lake site, on the Southern High Plains of Texas, contains one of the most complete and best-dated late Quaternary records in North America. A total of 11714C dates arc available from the site, determined by the Smithsonian and SMU Laboratories. Of these dates, 84 have been derived from residues (humin) and humates (humic acids) of organic-rich marsh sediments and A horizons of buried soils. Most of the ages are consistent with dates determined on charcoal and wood, and with the archaeologic and stratigraphic record. The dates on the marsh sediments are approximate points in time. Dates from the top of buried A-horizons are a maximum for burial and in many cases are close to the actual age of burial. Dates from the base of the A-horizons are a minimum for the beginning of soil formation, in some cases as much as several thousand years younger than the initiation of pedogenesis. A few pairs of dates were obtained from humin and humic acid derived from split samples; there are no consistencies in similarities or differences in these age pairs. It also became apparent that dates determined on samples from scraped trench walls or excavations that were left open for several years are younger than dates from samples taken from exactly the same locations when the sampling surfaces were freshly excavated.
Radiocarbon Dating of Lake Sediment from Two Karst Lakes in Yugoslavia
Authors: Srdoč Dušan , Obelić Bogomil , Horvatinčić Nada , Krajcar-Bronić Ines , Marčenko Elena , Merkt Joseph , Wong How Kin , Sliepčević Adela
Published: July 2016

Samples of sediment cores from two lakes in the karst area of northwest Yugoslavia were analyzed. Both Lakes Kozjak and Prošće are in the Plitvice National Park, Central Croatia. 14C dating, sedimentologic, seismic, and isotopic studies, and distribution of diatoms are presented.

14C dating of lake marl revealed a uniforn sedimentation rate in Lake Prošće as opposed to Lake Kozjak. Both lake sediments belong to the Holocene period. 14C dating of lake sediment is in agreement with seismic profiles, sedimentologic analysis, and diatom frequency measurements both in an undisturbed as well as in a disturbed lake sediment.
Multiple Dating of a Long Flowstone Profile
Authors: Geyh Mebus A , Hennig G J
Published: July 2016

Dense speleothem samples are considered as closed systems and are, therefore, possibilities for any dating method. Four dating methods (14C, U/Th, paleomagnetism, and electron spin resonance = ESR) were used for samples up to 1,000,000 yr old and taken along a vertical flowstone profile in the Heggen cave in West Germany. Also δ18O and δ13C analyses were carried out.

The reliability of the results of each method is dependent on the diagenetic processes that took place during the complex growth history of the flowstone. Speleothem growth was interrupted during glacial periods. During interglacial periods, at least the stalagmite growth rate was greater by one order of magnitude than during interstadial periods. During the periods of low interstadial growth rate various processes might have changed the 14C, 18O, and 13C concentrations, leaching might have removed uranium, recrystallization might have moved thorium several centimeters, and increased content of radon in the cave might have exaggerated the accumulated dose (AD) at the speleothem surface. As a result, 14C ages may be too small and U/Th as well as ESR data may be too large.
The Effects of Contamination of Calcareous Sediments on their Radiocarbon Ages
Authors: Srdoč Dušan , Horvatinčić Nada , Obelić Bogomil , Krajcar-Bronić Ines , O'Malley Peg
Published: July 2016

Two principal reasons for the inherent uncertainty in 14C dating of calcareous sediments such as tufa or those of lacustrine origin are the unknown initial 14C activity (Ao) of the sediment, mainly affecting younger (Holocene) samples, and contamination of older sediments with recent carbonate, causing 14C ages to be excessively young. To assess the contamination effect, samples of old tufa from the Riss/Würm interglacial were examined. These sediments contain essentially no 14C except that contributed by surface contamination. Tufa samples were crushed and grains ranging in size from <1 mm, 1 to 2mm, up to 4 to 5mm were separated for analysis; 2M HCl was then used to dissolve the samples in successive steps. 14C measurements indicated that each subsequent soluble fraction obtained from porous tufa gave a successively older age, indicating that the surface of the sample was contaminated by younger carbonates. No consistent effect of grain size on the 14C age was observed. Compact tufa proved to be less subject to contamination. 14C ages obtained on this material were also too young, yet older than the age obtained from porous tufa samples.

14C ages of interglacial tufa were cross-checked with the 230Th/234U dating method, using samples of very clean calcite which overlies the tufa blocks. Inferred 230Th/234U ages of the interglacial tufa (which had yielded 14C dates ranging from 25,000 to 37,000 yr) coincided with the last interglacial (Riss/Würm, Stage 5). Samples of Holocene tufa, in which contributions of recent 14C from surface contamination would pose less of a problem, yielded 14C and 230Th/234U dates which were in excellent agreement.
Use of AMS 14C Analysis in the Study of Problems in Aspartic Acid Racemization-Deduced Age Estimates on Bone
Authors: Ennis Paul , Noltmann E A , Hare P E , Slota P J , Payen L A , Prior C A , Taylor R E
Published: July 2016

Major discordances between AMS 14C- and aspartic acid racemization (AAR)-deduced age estimates on bone samples have led to an examination of factors other than time and temperature that can fundamentally influence the degree of racemization observed in fossil bone. Our studies support previous suggestions that for many bone samples the chemical state of amino acids must be routinely considered if AAR-deduced age estimates are to be used to make meaningful chronologic inferences.
A Low-Cost Miniature Counter System for Radiocarbon Dating
Authors: Jelen Kazimierz , Geyh Mebus A
Published: July 2016

Despite the great potential of the AMS technique for14C dating of milligram samples, the use of multiple miniature counter systems is still promising. Investment costs are relatively low and long-term financing of age determinations can be held within bounds. We have developed a14C dating system containing 10 miniature counters for $30,000, whereas commercial systems usually cost more than $ 150,000. Counting is not quite as good as that of the technically more sophisticated commercial systems, but the disadvantage for routine work is not significant. CO2preparation and purification take less than 30 minutes of active work including measurement and data evaluation. The cost of one age determination on a 22mg sample is about $35.00.
Optimization of Liquid Scintillation Counting for 14C Dating
Authors: Angiolini Fernando E , Albero Miguel C
Published: July 2016

The effects of different measurement conditions and sample preparation in liquid scintillation counting of benzene for 14C dating were tested. The goal of this work was to find the highest figure of merit through the variation of scintillation cocktail to benzene ratio, and measurement windows. Measurements were performed on 5ml of benzene plus increasing quantities of scintillation cocktail (7g of PPO and 0.5g of Me2POPOP in 1L of scintillation-grade toluene). Spectra of both background and standard were obtained and the counting windows selected for the highest figure of merit (Q). The best condition was 5ml of benzene plus 0.75ml of scintillation cocktail. This spectrum is compared with that of 1) pure toluene-14C plus cocktail, and 2) pure benzene-14C in which the equivalent amount of PPO and Me2POPOP present in 0.75ml of cocktail was dissolved. A correlation between the increase of the amount of cocktail and the broadening of the spectrum was observed. The effect of wrapping the upper part of the counting vial with aluminum foil to reduce background was also tested. A drastic background increment was observed in the low energy range, for unwrapped vials; the standard spectrum showed a broadening and a lower counting efficiency which reduced the figure of merit.
Environmental 14C Levels Around the 632 MWe Nuclear Power Plant Krško in Yugoslavia
Authors: Obelić Bogomil , Krajcar-Bronić Inks , Srdoč Dušan , Horvatinčić Nada
Published: July 2016

Measurements of 14C activity of atmospheric CO2, vegetables, and tree rings in the area of the 632 MWe power plant Krško in Slovenia, NW Yugoslavia, have been in progress since January, 1984. Sampling stations are located in the area ca 400km2 and are distributed in the direction of the prevailing westerly winds. The closest sampling point is 1.5km NE of the plant exhaust stack, the farthest sampling point is 30km E of the plant. A sampling site at National Park Plitvice in central Croatia was chosen as the 14C reference point not affected by the power plant.

An average excess of 2.2% above the reference point activity during normal periods of reactor operation was observed 1.5km from the plant smokestack. Calculations of the 14C release from the power plant was estimated at 0.1 TBq/a. The tree ring activity near the plant followed the 14C activity of the Northern Hemisphere in the past decade. No influence of the power plant release was observed on the tree ring activity.
Anthropogenic Radiocarbon: Past, Present, and Future
Authors: Povinec Pavel , Chudý Martin , Šivo Alexander
Published: July 2016

14C is one of the most important anthropogenic radionuclides released to the environment by human activities. Weapon testing raised the 14C concentration in the atmosphere and biosphere to +100% above the natural level. This excess of atmospheric C at present decreases with a half-life of ca 7 years. Recently, a new source of artificially produced 14C in nuclear reactors has become important. Since 1967, the Bratislava 14C laboratory has been measuring 14C in atmospheric 14CO2 and in a variety of biospheric samples in densely populated areas and in areas close to nuclear power plants. We have been able to identify a heavy-water reactor and the pressurized water reactors as sources of anthropogenic 14C. 14C concentrations show typical seasonal variations. These data are supported by measurements of 3H and 85Kr in the same locations. Results of calculations of future levels of anthropogenic 14C in the environment due to increasing nuclear reactor installations are presented.
Standardizing Procedures for Collecting, Submitting, Recording, and Reporting Radiocarbon Samples
Authors: Kra Renee
Published: July 2016

A new radiocarbon sample record form has been compiled for consensus among radiocarbon daters and users. The form is designed to obtain comprehensive standardized documentation of radiocarbon dates for reporting and disseminating valuable data. This method of reporting 14C dates will help resolve problems which include: 1) publication of all dated samples, 2) selection of significant samples, 3) interpretation of data, 4) recognition of problematic dates, 5) maintenance of an active archive of 14C dates, and 6) implementation of an international retrieval system for dates.
Groningen 14C Data Base
Authors: Engelsman F M R , Taayke E , Mook W G
Published: July 2016

Since May 1952 the Isotope Physics Laboratory in Groningen has dated ca 13,000 14C samples. Due to lack of time the publication of date lists in Radiocarbon ceased in 1971 and probably will not be resumed in the standard way. Most dates have been published but they are scattered over a great variety of books and articles.
Instituto Venezolano de Investigaciones Cientificas Natural Radiocarbon Measurements V
Authors: Tamers M. A.
Published: July 2016

The laboratory has been operating more than five years, supported entirely from Venezuelan government funds. Approximately 530 samples have been dated to the end of 1969. Of these, 40% are archaeologic specimens, the majority (141 samples) from Venezuela. Materials from most other countries of Latin America have been processed. The rest of the samples are from research programs of the Radiocarbon Laboratory itself. Thirty per cent of the total are measurements on carbonate species extracted from Venezuelan ground water aquifers.
Louvain Natural Radiocarbon Measurements IX
Authors: Gilot E.
Published: July 2016

The C14 dates given below have been obtained by counting CH4 at 3 atm pressure in a 0.6 L stainless steel counter. Details of procedure are given in the previous lists. Dates are reported in terms of the Libby half-life, 5570 ± 30 years; the errors quoted are based on the standard deviations in counting rate of samples and standards.
University of Pennsylvania Radiocarbon Dates XIII
Authors: Lawn Barbara
Published: July 2016

This date list includes those series of samples completed in this laboratory as of November 1969. The b.p. ages are based upon a.d. 1950, and are calculated with a half-life value of 5568 yr. All samples were counted at least twice for periods of not less than 1000 minutes each. Errors quoted are derived from measurement of samples, background, and modern-age calibration, but do not include any half-life error. All samples were pretreated with 3N HCl, and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic contaminants.
University of Pennsylvania Radiocarbon Dates XIV
Authors: Lawn Barbara
Published: July 2016

This date list includes those series of samples completed in this laboratory as of December 1970. The B.P. ages are based upon A.D. 1950, and are calculated with a half-life value of 5568 yr. All samples were counted at least, twice for periods of not less than 1000 minutes each. Errors quoted are derived from measurement of samples, background, and modern-age calibration, but do not include any half-life error. All samples were pretreated with 3N HCI, and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic contaminants.
Rehovot Radiocarbon Measurements I
Authors: Carmi I. , Noter Y. , Schlesinger R.
Published: July 2016

The Rehovot Radiocarbon Laboratory was established in 1968, as an extension of a low-level tritium laboratory, which has been in operation many years. Intended to be a supporting facility in geohydrological studies, the laboratory now offers general services in carbon dating.
Rhodesian Radiocarbon Measurements IV
Authors: Sheppard J. G. , Swart E. R.
Published: July 2016

The following list of dates was compiled since 1967 (R., 1967, v. 9, p. 382-386). Procedures of measurements are essentially unchanged from those reported previously (R., 1964, v. 6, p. 31-36; 1966, v. 8, p. 423-429). The only major change in procedure is that the practice adopted in previous date lists of widening the errors due to fluctuations in C14 content of the exchange reservoir has been discontinued. This leaves the users free to apply the necessary corrections as they become available, e.g., Stuiver and Suess (1966) and Ralph and Michael (1969). The two gas proportional counters were rebuilt in 1968. It was found that outgassing the polytetrafluoroethylene insulators at 100°C under vacuum for 48 hours prior to reassembling the counters considerably hastened attainment of stable operating conditions.