bluuebunny/crossref_metadata_2025 huggingface dataset:
Tbilisi Radiocarbon Dates III
Authors: Burchuladze A A , Gedevanishvili L D , Togonidze G I
Published: July 2016

The Radiocarbon Laboratory under the Chair of Nuclear physics of Tbilisi State University is engaged in studies of radiocarbon variation in the atmosphere and mineral waters and determination of the absolute age of archaeologic, geologic, botanical, and other samples. This list reports dates of archaeologic and geologic specimens only. Gas counting and liquid scintillation methods are used for dating.
Laboratory of Cosmochemistry Radiocarbon Measurements I
Authors: Lavrukhina A K , Alexeev V A
Published: July 2016

The 14C dates listed in this report on archaeologic and geologic samples were obtained mainly from 1969 to 1974. Pretreatment of wood charcoal and carbonized fossil soil by boiling in acid, alkali, and acid, again, is standard procedure. The method employed is liquid scintillation counting of synthesized benzene using the basic techniques described by Arslanov and Gromova (1968) converting sample → Li2C2 → C2H2 → C6H6 with an overall yield to ca 90%. A vanadium-alumina catalyst is used at reduced temperature for the acetylene to benzene conversion. Anthracite coal was used for the dead carbon run.
Monaco Radiocarbon Measurements V
Authors: Rapaire J L , Hugues G
Published: July 2016

Most of the 14C measurements reported here were made between October 74 and March 76. The usual procedures and methods of sample preparation are those described in R, 1964, v 6, p 194-196. The electronic apparatus was constructed by J Galliot from results of studies on background of proportional counters (Delibrias & Rapaire, 1967) and was described briefly in R, 1966, v 8, p 286-291.
University of Wisconsin Radiocarbon Dates XIV
Authors: Bender Margaret M , Bryson Reid A , Baerreis David A
Published: July 2016

Procedures and equipment of the laboratory have been described in previous date lists. Wood, charcoal, and peat samples are pretreated with dilute NaOH and dilute H3PO4 before conversion to the counting gas methane; marls and lake cores are treated with acid only. Very calcareous samples are treated with dilute HCl instead of H3PO4.
British Museum Natural Radiocarbon Measurements IX
Authors: Burleigh Richard , Hewson Andrew , Meeks Nigel
Published: July 2016

The following list consists of dates for archaeologic samples from countries other than the British Isles measured with a few exceptions over the period of mid-1970 to June 1974. The dates were obtained by liquid scintillation counting of benzene using a Model 3315 Packard Tricarb Liquid Scintillation Spectrometer. The laboratory procedures used were those outlined in the previous date list (R, 1976, v 18, p 16). As before, the dates, relative to ad 1950, are based on the Libby half-life for 14C of 5570 years, are corrected for isotopic fractionation (relative to the PDB standard) and are expressed in radiocarbon years uncorrected for natural 14C variations. NBS oxalic acid is used as the modern reference standard.
Hamburg University Radiocarbon Dates II
Authors: Scharpenseel H W , Schiffmann H
Published: July 2016

Radiocarbon measurements mainly on soil samples and soil organic matter fractions are being continued. Sample benzene preparation follows Scharpenseel & Pietig (1969; 1970a). Radioactivity is measured in single screw cap quartz vials using a Packard Tri-Carb 3075 as well as a Berthold Betaszint BF 5000.
Most Radiocarbon Dates I
Authors: Neustupny E F , Vesely K
Published: July 2016

The Laboratory of Applied Nuclear Physics of the Brown Coal Research Institute in Most started the radiocarbon dating of archaeologic samples in 1972. Dates presented in this list were obtained from 1973 to 1974.
US Geological Survey Radiocarbon Dates XII
Authors: Spiker Elliott , Kelley Lea , Oman Charles , Rubin Meyer
Published: July 2016

This list contains the results of some measurements made between 1968 and 1974. Samples were counted in the form of acetylene gas, as previously, and ages were computed on the basis of the Libby half-life, 5568 ± 30 years. The error listed, always larger than the 1σ statistical counting error commonly used, takes into account variable laboratory factors but does not include external (field or atmospheric) variations or fractionation.
Bratislava Radiocarbon Measurements II
Authors: Usačev S , Chrapan J , Oravec J , Sitár B
Published: July 2016

Radiocarbon dating facilities were built at the Department of Nuclear Physics, Comenius University in 1967 (Usačev et al, 1973). Initially, sample pretreatment and combustion systems for a proportional counter filled with CO2 were installed (Chrapan, 1966). One group adopted methods based on the use of methane (Usačev et al, 1973), a second group continued radiocarbon dating using an Oeschger-type proportional counter filled with CO2 (Chrapan, 1968). Later a modified Oeschger-type proportional counter with 1L active volume and with a background of approximately 8.10–2 bq was built (Schmidt and Chrapan, 1970). The pressure used in this counter is 105 Pa. 0.95 NBS oxalic acid is used as a standard of the present biosphere and the year 1950 refers to the zero year. Calculated radiocarbon ages are based on a 5568 ± 30 year half-life as recommended by the 8th International Radiocarbon Dating Conference. Statistical errors are calculated as a combination of the 3σ standard deviations of the sample count and the background. Samples were treated by HCl, NaOH or other chemicals according to their initial conditions.
Quebec Radiocarbon Measurements II
Authors: Barrette L , Lasalle P , Samson C
Published: July 2016

Experimental procedures and calculation remain almost as previously described in R, 1977, v 19, p 326-331. The only difference is in the counting equipment. We now use a Beckman LS-230 counter where samples are counted for a total count of about 30,000.
University of Wisconsin Radiocarbon Dates XV
Authors: Bender Margaret M , Bryson Reid A , Baerreis David A
Published: July 2016

Procedures and equipment of the laboratory have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH 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.
US Geological Survey, Denver, Colorado Radiocarbon Dates II
Authors: Schroder L J , Emerson R L , Beetem W A
Published: July 2016

This list includes all measurements made between 1969 and 1973 that represent natural samples. Physical and chemical treatment of samples and counting technique remain as previously reported (R, 1973, v 15, p 469-478). Calculations of dates are made with the radiocarbon half-life of 5568 ± 30 years; plus or minus numbers quoted herein are the standard errors for the counting of radioactive disintegrations.
British Museum Natural Radiocarbon Measurements X
Authors: Burleigh Richard , Hewson Andrew , Meeks Nigel , Sieveking Gale , Longworth Ian
Published: July 2016

The following list consists entirely of dates for archaeologic samples from the prehistoric flint mining site of Grime's Graves, Weeting, Thetford, Norfolk, England (52° 30' N, 0° 40' E, Natl Grid Ref TL 816898), measured over the period from August 1973 to December 1977,*all the samples having been excavated between 1972 and 1976. The dates were obtained by liquid scintillation counting of benzene using a Model 3315 Packard Tricarb Liquid Scintillation Spectrometer linked to a Hewlett Packard 2100A computer system for on-line processing of counting data (Hall & Hewson, 1977). The laboratory procedures used were those outlined in the two previous lists (R, 1976, v 18, p 16; 1977, v 19, p 143).
University of Saskatchewan Radiocarbon Dates VIII
Authors: Rutherford A A , Wittenberg J , Wilmeth R
Published: July 2016

This series reports some of the measurements made since publication of the previous list. Methods essentially remain as described in Saskatchewan II (R, 1960, v 2, p 73). The laboratory now joins operation with the National Museum of Canada, Ottawa. The prime purpose is to provide radiocarbon dating service for Canadian archaeologists through the National Museum, although commercial services are available to others as analytical capacity permits.
Gliwice Radiocarbon Dates V
Authors: Pazdur Anna , Pazdur Mieczyslaw F , Zastawny Andrzej
Published: July 2016

Most of the dates reported in this list were obtained between November 1975 and December 1976. All samples were subjected to standard de Vries pretreatment. Age calculations are based on a contemporary value equal to 0.95 of the activity of NBS oxalic acid standard and on the Libby value for the half-life of radiocarbon. Results are reported as conventional radiocarbon dates in years before ad 1950. All measurements were made with our L1 counter (Mościcki & Zastawny, 1976). Counting rates of all samples were normalized to the standard value of CO2 pressure and corrected for the counting efficiency (Pazdur et al, 1978). Errors quoted (±1σ) include estimated overall standard deviations of count rates for the unknown sample, contemporary standard and background (Pazdur, & Walanus, in press). No corrections for 13C/12C ratio were made for measurements reported in this list. The value of δ13C for our NBS oxalic acid standard is equal to — 19.41% relative to the PDB standard. The descriptions of the samples are based on information provided by the submitters.
La Jolla Natural Radiocarbon Measurements VIII
Authors: Linick T W
Published: July 2016

The following date list covers certain samples dated by this laboratory from Nov 1975 through December 1977. All archaeological, all geological, and some of the geochemical samples measured during that period are included here. Measurements of tree-ring samples analyzed through Sept 1977 have been published previously (Suess, 1978); later measurements of wood samples will be included in the next list. Data and interpretation of14C in the CaCO3of annual coral growth have been published (Druffel & Linick, 1978) with further coral data to be published in the future.
Scottish Universities Research and Reactor Centre Radiocarbon Measurements III
Authors: Harkness D D , Wilson H W
Published: July 2016

Results reported here are for samples of geologic context. Throughout the period of these analyses, viz, 1973 through 1975, the preparation of samples and operation of counting systems remained essentially as described in Radiocarbon, 1973, v 15, p 554 to 565.
University of Miami Radiocarbon Dates XVI
Authors: Introne D S , Johnson R , Stipp J J
Published: July 2016

Radiocarbon measurements have been continued on a variety of projects and materials. Chemical and counting procedures remain the same as indicated in R, v 20, p 274-282. Dates are calculated using the Libby 14C half-life of 5568 years; errors are reported as one-standard deviation (1σ) based only on statistical counting uncertainties in background, modern standard, and sample activities. All samples for which 13C/12C ratios are available are corrected for isotopic fractionation by normalizing to —25‰. A 400-year reservoir age correction has been applied to marine carbonates.
Vienna Radium Institute Radiocarbon Dates X
Authors: Felber Heinz
Published: July 2016

Measurements have continued with the same proportional counter system, pretreatment procedure, methane preparation and 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 IX
Authors: Polach H A , Rhodes E G , Head John , Gower John
Published: July 2016

During the last seven years, there has been a concerted effort in eastern Australia to obtain14C ages from detrital shell samples of prograded sand barriers composed of beach ridges and chenier deposits (Cook and Polach, 1973; Cook and Mayo, 1977; Thom, Polach, and Bowman, 1978; Thomet al, 1981). These ages were used to establish the age sequence of deposition and rates of progradation. This date list is the result of work in two areas of the Gulf of Carpentaria, Queensland, Australia, where 57 shell samples were collected for14C dating. For details of this research, see Rhodeset al(1980).
Gliwice Radiocarbon Dates VII
Authors: Pazdur Anna , Awsiuk Romuald , Bluszcz Andrzej , Pazdur Mieczysław F , Walanus Adam , Zastawny Andrzej
Published: July 2016

The following list contains the measurements of archaeologic samples made during 1978 and 1979 using carbon-dioxide-filled proportional counters. Most of the samples were dated with counter No. 3 (L3) filled to 1 or 2 atm pressure (Mościcki and Zastawny, 1977). Our counter No. 1 (L1) previously described (Mościcki and Zastawny, 1976) has been remounted and is now operating at 2 atm pressure of carbon dioxide. Samples measured with this counter have date numbers starting with Gd-1000. Parameters of proportional counters are listed in Table 1. Our transistorized electronics is being gradually replaced by more compact integrated-circuit electronics in CAMAC system (Bluszcz and Walanus, 1980). Counts from proportional counter and guard counters are recorded in 5 channels and punched every 100 minutes. Typical measurement of any sample, including background and oxalic acid samples, consists of a series of 20 to 25 partial measurements. Partial results obtained in such series are analyzed on ODRA 1325 computer at the Computing Centre of the Silesian Technical University according to code C14C written in ALGOL (Pazdur and Walanus, 1979). Age calculations are based on contemporary value equal to 0.95 of the activity of NBS oxalic acid standard and on the Libby value for the half-life of radiocarbon. Ages are reported as conventional radiocarbon dates in years before ad 1950. Corrections for isotopic fractionation in nature are made only for some samples with indicated values of δ13C Errors quoted (±1σ) include estimated overall standard deviations of count rates of the unknown sample, contemporary standard, and background (Pazdur and Walanus, 1979).
US Geological Survey, Menlo Park, California Radiocarbon Measurements III
Authors: Robinson Stephen W , Trimble Deborah A
Published: July 2016

The analyses in this list were performed between 1977 and 1979. The laboratory utilizes gas counting of carbon dioxide in counters installed 9.5 meters below the ground surface for background reduction. The reported results closely follow the guidelines of Stuiver and Polach (1977), although the standard error for analyses earlier than USGS-500 are based solely upon counting statistics and do not include uncertainty in voltage, pressure, temperature, and δ13C.
Calibrated14C Dates in Central Europe - Same as Elsewhere?
Authors: Freundlich J C , Schmidt Burghart
Published: July 2016

14C dating results derived from an absolutely-dated 471-year tree-ring sequence from central European oak show a trend towards somewhat older dates than those for bristleconepine tree rings of the same age, but similar to those for Egyptian historical samples. Differences visible between these trend lines are not relevant considering the standard errors proposed by Clark (1975).
Long-Term Variability of Temperature and 14C in the Gulf Stream: Oceanographic Implications
Authors: Druffel Ellen M
Published: July 2016

Variability in temperature and 14C levels are recorded in coralline aragonite that grew in the Gulf Stream during the past four centuries. In particular, 18O/16O ratios reflect a decrease of ca 1°C in surface water temperature during the latter part of the Little Ice age. 14C levels also rose in the surface waters of the Gulf Stream and in atmospheric CO2 during the Maunder minimum. These observations indicate that ocean circulation may have been significantly different in the North Atlantic around the beginning of the 18th century.
Radiocarbon Dating of Millimole-Sized Gaseous Samples
Authors: Srdoč Dušan , Obelić Bogomil , Horvatinčić Nada
Published: July 2016

As an alternative to the accelerator technique, a simple, compact, small counter system has been developed and tested for routine 14C dating. Our small counter is an all-metal design made of the OFHC copper with quartz supports for the anode (25μm stainless steel). Careful selection of materials for the counter construction was made based on the measurements of the alpha contamination. Methane as the counter filling gave better resolution and gas gain stability, whereas CO2 gave lower background counting rate and it was easier to prepare and to handle. The long term run using CH4 showed that the gas gain remained stable within 1–2% for months after the initial drop which followed the counter filling. A 7-day counting period was sufficient to achieve a 3% relative standard deviation which was considered acceptable for routine dating of younger samples.
The Radon Problem in14C Dating
Authors: Nydal Reidar
Published: July 2016

Due to traces of radium and uranium in most14C samples, radon appears as a radioactive contamination in the CO2prepared by combustion. This contamination must be removed by an active purification prodecure or by storing the CO2prior to measurement. No effective electronic discrimination against radon and its daughter elements can be performed. The necessary storage time until radon has decayed varies widely, especially for marine shells. The latter material, collected from Norway and Svalbard, has been a main object for the present investigation. In a few cases, a measureable amount of radon may be left even after eight weeks. The behavior of radon and its daughter elements in a CO2proportional counter has been studied.
Stable Isotope Fractionation During Benzene Synthesis for Radiocarbon Dating
Authors: Panarello Hector O , Albero Miguel C , Angiolini Fernando E
Published: July 2016

13C isotope analyses of different stages of benzene synthesis have been made to study partial isotope fractionation. More than 60 analyses of carbonates, charcoal, carbon dioxide, and benzene were made in a double collector mass spectrometer. In the first stage of the synthesis (conversion to carbon dioxide) little or no fractionation was observed, beyond the analytical error of the method. Later stages of the process, show a greater and systematic fractionation. The experimental techniques are described.
An Evaluation of Shielding Characteristics Applicable to Mini-Gas Proportional-Counter-Based 14C Dating Systems
Authors: Kaihola Lauri , Kojola Hannu , Polach Henry , Soini Erkki , Otlet Robert
Published: July 2016

A mini-gas-proportional counter prototype of 10ml capacity (at NTP) was constructed of oxygen-free Finnish copper. The counter tube will be one of 16 equivalent tubes of a small-sample gas counting system, which is equipped with passive graded shield made of lead, cadmium, and copper and a dual active anticoincidence shield, consisting of an external cosmic gas-proportional and an internal plastic scintillation guard. The aim of this study was to evaluate the parameters leading to the design of a cost-effective and compact shielding package for mini-counters.
The Reliability of Archaeologic Interpretation of 14C Dates
Authors: Willkomm Horst
Published: July 2016

14C dates of a medieval settlement with archaeologically well-dated strata are compared with the true ages of the respective layers. The 14C values indicate that each layer may contain older material reaching up to the beginning of settlement. Therefore, the 14C measurement of only a few wood or charcoal samples may lead to age estimations several hundred years too old.
Radioisotope Dating with the ETHZ-EN-Tandem Accelerator
Authors: Woelfli Willy , Bonani Georges , Suter Martin , Balzer Richard , Nessi Marzio , Stoller Christian , Beer Juerg , Oeschger Hans , Andrée Michel
Published: July 2016

During the last three years the ETH-EN-tandem accelerator facility has been adapted for the quantitative determination of the rare isotopes 14C and 10Be in mg samples. The goal of this project is to routinely achieve a 1% accuracy when measuring 14C/12C ratios with a minimum expenditure of human resources and beam time. The concept is similar to that proposed by Purser and Henley (1978). The early evolution of this dating facility was described previously (Suter et al, 1981a,b). This paper is a brief report on the current status of the system and its development.
Survey of Simple Carbon Compounds for Use in a Negative Ion Sputter Source
Authors: Vogel J S , Nowikow I G , Southon J R , Nelson D E
Published: July 2016

We present a survey of carbon beam yields from 20 simple carbon compounds using a caesium sputter source and the McMaster University tandem accelerator. The carbon yield was measured as a 35MeV 12C4+ beam. We found that the beam intensities could be related to a grouping of the carbides according to the chemical bonding of the compounds. The usefulness of the compounds for accelerator 14C dating was further related to their preparation chemistries. Strontium carbide was the equal of graphite in negative carbon ion beam production and aluminum carbide was found to be a good candidate for further tests because of its good sputter yield and preparation chemistry. Charcoal was also tested with varying amounts of silver added as a heat conduction aid.
Bomb 14C in the Ocean Surface 1966–1981
Authors: Nydal Reidar , Gulliksen Steinar , Lövseth Knut , Skogseth Fred H
Published: July 2016

Bomb 14C has been used as a tracer for CO2 in ocean surface water to study CO2 exchange between atmosphere and ocean. Using ordinary cargo ships for sampling, we have been able to cover some parts of the Atlantic, Pacific, and Indian Oceans for certain periods. A total number of 520 samples from 89 locations were measured during the last 15 years. The data are presented both in tables and graphs. A maximum 14C concentration (Δ14C) of ca 20% was observed in temperate northern latitudes, and a few per cent lower at southern latitudes. A seasonal trend in the 14C variation, with summer maximum and winter minimum, was observed both in downwelling and upwelling areas.
Lodz Radiocarbon Dates I
Authors: Kanwiszer Andrzej , Trzeciak Pawel
Published: July 2016

The Radiocarbon Laboratory of the Archaeological and Ethnographical Museum in Lódź was established to meet the growing demand for radiocarbon dating of archaeologic and geologic samples. The liquid scintillation technique based on the Polish liquid scintillation counter with a single photomultiplier began operation in 1966. The base for the measurements was ethylbenzene. In 1974 new facilities for the determination of radiocarbon assays were installed. The proportional counter and the electronics supplied by Nuclear Enterprises became routine counting equipment two years later.
Museo De La Plata Radiocarbon Measurements I
Authors: Figini Anibal , Gomez Gabriel , Carbonari Jorge , Huarte Roberto , Zubiaga Alicia
Published: July 2016

The reinstallment, operation, and the14C measurements reported here were made since 1976 in the LATYR, the Radiocarbon Dating Laboratory of the Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata. Sample preparation is preceded by careful visual separation and hand removal of gross impurities. This is followed in all cases (charcoal, wood) with successive washings of the sample with boiling 2% HCl and 1% NaOH solution for removal of carbonates and humic acids. Thereafter, it is washed with distilled water and acidified to pH = 3. Individual variations in the pretreatment are not described in the date list, but they are usually reported directly to the collector together with the data obtained.
Geological Survey of Japan Radiocarbon Dates I
Authors: Togashi Shigeko , Matsumoto Eiji
Published: July 2016

This radiocarbon laboratory began operation in 1980 using the benzene scintillation method. The benzene synthesizer is essentially identical with that of Ikeda (1976). A liquid scintillation counter is Aloca LSC-LB1. Samples dated are wood, charcoal, shell, and coral.

Pretreatment of wood and charcoal is a standard acid-alkali procedure, using 2% HCl and 2% NaOH at elevated temperatures. Charcoal is further heated in concentrated HNO3 for one hour, diluted in water, stands one night, and is washed and dried. Pretreated wood and charcoal are carbonized before combustion. The combustion products are passed over CuO, and are collected in an ammonium hydroxide bubbler system, and precipitated with calcium chloride.
University of Saskatchewan Radiocarbon Dates X
Authors: Rutherford A A , Wittenberg Jurgen , Gordon B C
Published: July 2016

This series reports some of the measurements made since publication of the last list (R, 1981, v 23, p 94–135). Also included are a number of earlier dates previously withheld pending submitter evaluation. For some the authors have been unable to obtain appropriate comment. References to other publication of these dates are given where known.

Acetylene proportional gas counting methods essentially remain as described in Saskatchewan II (R, 1960, v 2, p 73). Bone dating is carried out on soluble collagen extract (Longin, 1971) since 1978.
Physical Research Laboratory Radiocarbon Date List V
Authors: Agrawal D P , Krishnamurthy R V , Kusumgar Sheela
Published: July 2016

We report here dates on archaeologic and geologic samples. The samples were counted as methane in gas proportional counters. The techniques used have been described earlier (R, 1971, v 13, p 442–449). Dates are expressed in years BP, taking AD 1950 as the reference year. Modern standard was NBS oxalic acid. Quoted errors are based on counting statistics alone and are equivalent to ±1 standard deviation for samples younger than 10,000 years and ± 2 standard deviations for older samples. Descriptions and references regarding the samples have been supplied by the submitters of the samples.
Amplitude of Sunspot-Dependent Radiocarbon Variations: Data from Corals and Wine
Authors: Magaritz Mordeckai , Carmi Israel , Sirkes Ziv
Published: July 2016

It has been suggested that the sunspot cycle modulates the production rate of radionuclides in the atmosphere and that these modulations can be traced in various parts of the earth surface system. On the basis of a theoretical analysis, Damon, Sternberg, and Radnell (1983) have concluded that the effects of the 11-yr cycle of sunspots should be observable in 14C data provided the measurements are done at a 2 permil (sd) level. This conclusion is based on calculations using models discussed by Lingenfelter and Ramaty (1970) and by O'Brien (1979) and on the 14C inventory modified from Damon, Lerman, and Long (1978). In this note we compare the amplitude estimate of Damon, Sternberg, and Radnell (1983), who calculated a representative peak-to-peak variation of 1.7‰ in 14C for the sunspot cycle between 1848 and 1856, with experimental values derived from recently published data. We find the experimental value to be larger by a significant factor from the theoretical calculation.
Progress at the Isotrace Radiocarbon Facility
Authors: Beukens Roelf P , Gurfinkel Debbie M , Lee Henry W
Published: July 2016

Since August 1984 over 100 samples have been analyzed. 12C, 13C, and 14C isotopes were measured after acceleration and all dates were corrected for natural and preparation-induced fractionation. A precision of better than 1.0% was obtained for samples 10,000 yr BP or less and these results were shown to be reproducible at precision levels as low as 0.3%. An accuracy of better than 1.0% was demonstrated for the same age range by analyzing samples which were previously dated with the conventional technique. The machine background, measured on blank sample holders in a clean ion source, yielded a count rate equivalent of 0.015 ± 0.007% modern.
Carbon Cycle: 1985 Glacial to Interglacial Changes in the Operation of the Global Carbon Cycle
Authors: Broecker Wallace S , Peng Tsung-Hung
Published: July 2016

The hottest topic for those interested in the earth's carbon cycles is the change in atmospheric CO2 content between glacial and interglacial time. What caused it? What is its role in glacial cycles? We evaluate here the hypotheses that have been put forward to explain the CO2 change with evidence from deep sea sediments. We conclude that all the hypotheses have serious drawbacks and that much effort will have to be expended in gathering more data from ice cores and ocean sediments before we will be pointed toward the correct scenario. Also, thoughtful modeling aimed at depicting the ties between pCO2, O2,13C/12C, 14C/12C, and nutrient constituents in the sea for various modes of circulation will have to be done before the evidence from ocean cores can be properly interpreted.
The Use of Natural and Anthropogenic 14C to Investigate the Dynamics of Soil Organic Carbon
Authors: O'Brien Bernard John
Published: July 2016

Radiocarbon has been measured in two soil profiles, one of which has been covered by a building since 1956. A comparison of the Δ14C values in horizons of each profile gives an estimate of the total input of atom bomb 14C into the soil profile. From the Δ14C and carbon density profile data, the carbon input rates, respiration rates, and diffusivity are calculated. The lack of vegetation on one soil affects the mobility and the respiration rate of the soil carbon in that soil. The data from this soil profile are also used to check the assumption, used in previous analyses, that there is a uniform distribution of ‘old’ carbon down the soil profile. The input rate, turnover time, and diffusivity parameters determined from the Δ14C profiles in these soils are compared with other published data on pasture and forest soils.
Trends of 13C/12C Ratios in Pinyon Tree Rings of the American Southwest and the Global Carbon Cycle
Authors: Leavitt S W , Long Austin
Published: July 2016

An accurate atmospheric 13C/12C chronology can provide important constraints to models of the global carbon cycle. Trees accumulate carbon from atmospheric CO2 into growth rings and offer potential for 13C/12C reconstructions, but results have not been reproducible. This paper presents δ13C curves from 5 sites, representing 20 pinyon (Pinus edulis) trees, where cores of 4 trees from each site have been pooled into a composite sample. Isotopic analysis of cellulose in 5-yr ring groups produces curves with a general trend of decreasing δ13C after 1800, but with pronounced short-term fluctuations superimposed upon the trend. Evidence indicates the fluctuations are strongly related to moisture availability (drought). A mean curve of the 5 δ13C chronologies from which the fossil-fuel component is subtracted suggests a substantial biospheric CO2 contribution to the atmosphere since 1800.
14C in the Deep Water of the East Atlantic
Authors: Schlitzer Reiner
Published: July 2016

The renewal of east Atlantic deep water and its large-scale circulation and mixing have been studied in observed distributions of temperature, silicate, ΣCO2, and 14C. 14C variations in northeast Atlantic deep water below 3500m depth are small. Δ14C values range from − 100‰ to −125‰. 14C bottom water concentrations decrease from Δ14C =−117‰ in the Sierra Leone Basin to Δ14C = − 123‰ in the Iberian Basin and are consistent with a mean northward bottom water flow. The characteristic of the water that flows from the west Atlantic through the Romanche Trench into the east Atlantic was determined by inspection of θ/Δ14C and θ/SiO2 diagrams. A mean potential temperature of θ = 1.50 ± .05°C was found for the inflowing water. A multi-box model including circulation, mixing, and chemical source terms in the deep water has been formulated. Linear programing and least-squares techniques have been used to obtain the transport and source parameters of the model from the observed tracer fields. Model calculations reveal an inflow through the Romanche Trench from the west Atlantic, which predominates over any other inflow, of (5 ± 2) Sv (potential temperature 1.50°C), a convective turnover of (150 ± 50) years and a vertical apparent diffusivity of (4 ± 1) cm2/s. Chemical source terms are in the expected ranges.
Revealing Histories of Exposure Using In Situ Produced 26Al and 10Be in Libyan Desert Glass
Authors: Klein Jeffrey , Giegengack Robert , Middleton Roy , Sharma Pankaj , Underwood J R , Weeks R A
Published: July 2016

We present the results of measurements of 26Al and 10Be produced in situ in 12 samples of Libyan Desert Glass by cosmic rays during the last ten million years. Based on the variability of the concentrations of 10Be and of the 26Al/10Be ratios we measured, we conclude that individual fragments of glass have experienced different exposure histories, implying several major redistributions of the glass within the past 106 years. The 26Al and 10Be concentrations are inconsistent with the theoretical estimates of the rates of in situ production. We estimate minimum production rates of 70 atoms g-1 yr-1 and 10 atoms g-1 yr-1 for 26Al and 10Be, respectively, produced in quartz at sea level between 60–90° latitude. Despite the present uncertainty in the rates of production, we feel that these results show clearly the effectiveness of in situ produced 26Al and 10Be in studying earth-surface processes.
The Potential of the London Underground for Liquid Scintillation Counting
Authors: Bowman Sheridan
Published: July 2016

A portable gamma spectrometer has been used to survey three locations that are part of the London Underground Transport System (the “tube”). Up to an order of magnitude reduction in the cosmic ray flux was observed relative to the laboratory level. The likely reduction in background count rate achievable by underground siting of currently used Packard and LKB liquid scintillation counters is considered. It is noted that in the present, surface usage for radiocarbon dating, the background count rate of low-potassium glass vials in the LKB is not substanially higher than that of PTFE vials.
Archaeologic Sherd Dating: Comparison of Thermoluminescence Dates with Radiocarbon Dates by Beta Counting and Accelerator Techniques
Authors: Johnson R A , Stipp J J , Tamers M A , Bonani Georges , Suter Martin , Wölfli Willy
Published: July 2016

Sherds can be dated by four independent methods: 14C beta counting on associated material, accelerator mass spectrometry on carbon traces on and within the sherd, thermoluminescence studies on minerals within the sherd, and stylistic form. Age analyses of materials and sherds from several sites are shown in this work. Each technique has its own frequently encountered non-laboratory sources of error. A combination of at least two independent techniques is indispensable for the highest level of confidence.
Is Radiocarbon Dating Obsolescent for Archaeologists?
Authors: Ottaway Barbara S
Published: July 2016

This paper will deal with two major points: 1) the lack of feedback between archaeologists supplying samples and using radiocarbon dating, and physicists carrying out 14C dating measurements; and 2) the problem of calibrating groups of 14C dates in a statistically meaningful way.
Toward a Thesaurus of Radiocarbon Dating and Related Terms
Authors: Polach Dilette
Published: July 2016

The development of a Thesaurus of Radiocarbon Dating and Related Terms was undertaken to provide a basic common vocabulary of terms for the purpose of indexing an Annotated Bibliography of Radiocarbon Dating (1948–68) and form the basis of a language for information storage and retrieval in 14C dating and related term areas. The interdisciplinary nature of 14C dating dictates that selected terms have meanings in the context of archaeology, geology, earth sciences, oceanography, and environmental sciences, to name but a few, as well as chemistry and nuclear instrumentation on which the technique of 14C determinations is based. This paper describes the method used for selection of terms and explains the structure of the proposed thesaurus. A limited edition Draft Thesaurus was distributed to a selected panel of colleagues for critical evaluation.
Atomic Energy Research Institute of Korea Radiocarbon Measurements I
Authors: Yang Kyung Rin
Published: July 2016

This radiocarbon dating laboratory was established to complement the research activities in the field of archaeology and geology in Korea. The benzene liquid scintillation counting method (Noakes, Kim, and Stipp, 1965; Noakes, Kim, and Akers, 1967) is employed in this laboratory because of its compatibility with other dating methods and future possibility in application of this procedure to the biomedical research field. The chemical process for converting carbon from a sample to benzene used by this laboratory is briefly outlined below.
University of Wisconsin Radiocarbon Dates VIII
Authors: Bender Margaret M. , Bryson Reid A. , Baerreis David A.
Published: July 2016

Radiocarbon dates obtained since August 1969 are included in this report. The procedures followed and equipment used have been described previously (Radiocarbon, 1966, v. 8, p. 522-533).
University of Bonn Natural Radiocarbon Measurements IV
Authors: Scharpenseel H. W. , Pietig F.
Published: July 2016

Radiocarbon measurements, mainly on soil and water samples have been continued. Sample preparation is carried out following methods described by the authors elsewhere (Scharpenseel and Pietig, 1968/69; 1970a, b).
University of Kiel Radiocarbon Measurements VI
Authors: Erlenkeuser H. , Willkomm H.
Published: July 2016

This list contains data obtained during 1970. Age calculations are based on 95% of NBS oxalic acid standard activity with modern value A.D. 1950. Results are calculated using the Libby half-life and are given in the B.P. scale. They are not corrected for δC13 variations. Errors correspond to 1σ variation of sample net counting rate including statistics of modern standard and background.
Louvain Natural Radiocarbon Measurements XI
Authors: Gilot E. , Capron P. C.
Published: July 2016

The following list comprises selected measurements obtained by counting methane at 3 atm pressure in a 0.6 L stainless steel counter. Sample preparation, counting procedure, and calculation method are described in previous lists. Dates are reported in terms of the Libby half-life. The quoted errors are the experimental standard deviations including uncertainty on samples and standards.
University of Wisconsin Radiocarbon Dates IX
Authors: Bender Margaret M. , Bryson Reid A. , Baerreis David A.
Published: July 2016

Radiocarbon dates obtained since December, 1969, are summarized here. Procedures and equipment have been described previously (R., 1966, v. 8, p. 522). Wood, charcoal, and peat samples are pretreated with dilute NaOH 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.
Tata Institute Radiocarbon Date List X
Authors: Agrawal D. P. , Kusumgar Sheela
Published: July 2016

In this date list we present dates from some very important archaeologic and Quaternary sites. For the first time the temporal spread of the Neolithic cultures of Bihar and the transformation of the Harappa culture in Gujarat has been dated. Some of the sites of controversial antiquity in Pakistan and India also have now been unambiguously dated.
University of Wisconsin Radiocarbon Dates XI
Authors: Bender Margaret M. , Bryson Reid A. , Baerreis David A.
Published: July 2016

This report includes radiocarbon dates obtained since December 1971. Procedures and equipment have been described previously (R., 1966, v. 8, p. 522).
Berlin Radiocarbon Dates V
Authors: Kohl G , Quitta H
Published: July 2016

The dates presented in this paper comprise results of determinations made on archaeologic and geologic material from Socialist Republic Vietnam since 1969. Radioactivity was measured twice for 48 hours with gas proportional counters of Houtermans-Oeschger type, using methane at 1000mm Hg pressure as filling gas. Influence of cosmic and local environmental radiation on the counters was reduced with 30 tons of shielding material as described earlier (R, 1970, v 12, p 400-420).
Gliwice Radiocarbon Dates IV
Authors: Moscicki Wlodzimierz , Pazdur Anna , Pazdur Mieczyslaw F , Zastawny Andrzej
Published: July 2016

All samples described in this date list have been measured since July 1973 to Oct 1975 using carbon dioxide filled proportional counters. Most of samples have been dated with Counter No. 1 (LI) as in our previous list (Mościcki and Zastawny, 1976). Some samples were measured with Counter No. 3 (L3), with a total volume of 1.51 and background and NBS oxalic acid standard counting rate of respectively, 3.50 or 4.00 cpm and 10.05 or 20.40 cpm when filled to 1 or 2 atm pressure (Mościcki and Zastawny, 1977).
Uppsala Natural Radiocarbon Measurements XII
Authors: Olsson Ingrid U , Farid M , El-Daoushy A F
Published: July 2016

The following list covers all bone sample measurements finished since the last list (R, 1972, v 14, p 247-271) until the end of 1977; the Egyptian samples were measured as an interlaboratory project and all shells were closely related to some of the bone samples.
University of Miami Radiocarbon Dates XIII
Authors: Calvert P M , Introne D S , Stipp J J
Published: July 2016

The following radiocarbon dates are a partial list of samples measured since Sept 1977. The chemical and counting procedures are the same as indicated previously (R, 1978, v 20, p 134-138).
14C Variations Caused by Changes in the Global Carbon Cycle
Authors: Siegenthaler Ulrich , Heimann Martin , Oeschger Hans
Published: July 2016

A box-diffusion model for the carbon cycle is used to estimate the magnitude of 14C variations caused by changes of reservoir sizes and exchange fluxes in the global carbon system. The influence of changes in atmospheric CO2 concentration, biomass, CO2 exchange rate between atmosphere and ocean, and ocean mixing is considered. Steady-state 14C concentrations as well as the transients are calculated. For changing biomass, atmospheric CO2 levels and 13C/12C ratios are also calculated.

Carbon-cycle-induced 14C variations may have been significant in the transition period from Glacial to Postglacial when drastic changes in environmental conditions took place within short time periods, while they were probably less important during the climatically more stable Postglacial.

Changes of the oceanic circulation, as supposedly occurred, are considered the most important factor, besides variations of the production rate, affecting the global distribution of 14C. 14C variations due to changes of the atmospheric CO2 level or the air-sea-exchange probably did not exceed one to a few percent. Fluctuations of the forest biomass, which may have occurred between Glacial and Postglacial, hardly affected the 14C concentration over a long term.

Responses of the atmospheric 14C concentration are also calculated for variations of the 14C production rate by cosmic radiation. The following cases are considered: a step change, square-wave changes producing “wiggles”, and sinusoidal variations.
Accuracy of the Radiocarbon Time Scale Beyond 15,000 BP
Authors: Vogel J C
Published: July 2016

Ionium dates for the Upper Lisan Formation in the Dead Sea valley average (10 ± 3) percent higher than a set of radiocarbon dates from the same profiles. No analytical explanation can be found so that the discrepancy may be real for the period 15,000 BP to 35,000 BP (conventional radiocarbon years). This would have implications for the chronology of the Upper Pleistocene.
Temporal Variations in Cosmogenic 10BE Production: Implications for Radiocarbon Dating
Authors: Raisbeck G M , Yiou Françoise
Published: July 2016

A procedure is outlined for using cosmogenic 10Be variations in polar ice cores and lake or inland sea sediments to correct for 14C production variations in the past. Some of the requirements and problems associated with such a procedure are discussed.
Medium-Term Atmospheric14C Variations
Authors: De Jong A F M , Mook W G
Published: July 2016

High-precision14C measurements are presented, carried out on single tree rings from a section of the floating South German Neolithic tree-ring chronology. They confirm the existence of pronounced medium-term variations in the order of 2 percent during the 33rd to 38th centuries BC.

These variations turn out to be very regular while the precision of 1.5‰ allows a comparison with a geochemical model calculation. Good agreement is acquired for an input function with a periodicity of about 150 years and an amplitude of approximately 30 percent in the14C production rate.
Comparison of14C Dates and Other Age Estimations Between 2000 BC and AD 1000
Authors: Willkomm Horst
Published: July 2016

The14C age of charcoal and wood from Lebanon and central Europe is compared partly with the dendrochronologically determined age of the samples and partly with the archaeologically expected value. While the dendrologic values approximately confirm the correction curve of Ralph, Michael, and Han (1973), charcoal of burned layers seemes to be generally 2 to 3 centuries older than expected from contemporary archaeologically retrieved materials.
14C and Other Parameters During the Younger Dryas Cold Phase
Authors: Oeschger Hans , Welten Max , Eicher Ulrich , Möll Markus , Riesen Trudi , Siegenthaler Ulrich , Wegmüller Samuel
Published: July 2016

Pollen analysis as well as18O/16O results on lake marl show that the Younger Dryas climatic period, between about 11,000 and 10,300 bp, was the last vigorous cold phase of the Würm Glacial. Detailed14C analyses from a peat bog near Wachseldorn (Switzerland) point to a14C anomaly in this period. Further indication of a14C anomaly is given by the observation that, during the Younger Dryas period, the sedimentation rates in several lakes apparently were higher than in adjacent periods; an explanation might be that the14C time scale was compressed between 11,000 and 10,000 bp,ie, the atmospheric14C/C ratio varied. If real, this suggested14C variation would probably be connected to the climatic events during this transition period from Later Glacial to Postglacial.
High Precision Radiocarbon Dating by Liquid Scintillation Counting Applied to Radiocarbon Time-Scale Calibration
Authors: Pearson Gordon W
Published: July 2016

The precision quoted on a radiocarbon date is often misleading. Improvement in the accuracy of measurement is discussed together with the use of appropriate precisions. The effect of high accuracy in 14C dating and meaningful precisions are illustrated and applied to radiocarbon time-scale calibration. Intercomparison of such calibrations reveals a significant continuous saw-tooth pattern of short-term periodicity.
Variations of 14C in Oats Grown from 1957 to 1978 in Quebec
Authors: Barrette Louis , Lasalle Pierre , Martel Yvon , Samson Claude
Published: July 2016

Annual atmospheric radiocarbon concentrations for the year 1957 to 1978 are measured through oat seeds grown in the rural region of La Pocatière, Québec (70° W, 47° N). Results follow the general pattern of other curves obtained from grains elsewhere in the northern hemisphere. Some disagreements suggest a non-uniform mixing process with faster response to stratospheric contamination in definite regions.
A Multi-Counter System for High Precision Carbon-14 Measurements
Authors: Schoch Hildegard , Bruns Michael , Münnich Karl Otto , Münnich Marianne
Published: July 2016

A new 14C detector system containing nine, independently working, CO2 proportional counters is described. The system is designed for a sufficient measuring capacity at a precision level better than σ = ± 2‰, which requires a counting time of about one week per sample. The size of the installation requires a simple and economic design of counters and electronics. A single anticoincidence shield for all counters consists of five newly developed flat counters. The modern counting rate (52cpm) is sensitively checked by running Heidelberg sodium carbonate standard samples wth a counting rate of about 10 times modern. A microcomputer (DEC PDP-11 /03) is used for data acquisition. Recent developments in laboratory techniques (preparation and gaschromatographic purification of samples) are also reported.