• Radioactive Graphite Dispersion in the Environment in the Vicinity of the Chernobyl Nuclear Power Plant

      Buzinny, Michael (Department of Geosciences, The University of Arizona, 2006-01-01)
      This paper estimates the radioactive graphite dispersion on the land surface (forest litter and soil) as a result of the Chernobyl Nuclear Power Plant (NPP) release. Graphite mass was calculated using an estimated average concentration of 2.5 x 10^7 Bq/kg C (carbon). The sample collection method, sample origin and its mass, and sample preparation procedure used for preparation of benzene were taken into account to obtain the optimum sensitivity of the method. Thus, the sensitivity of the corresponding method for graphite detection in forest litter was estimated to be 0.2 mg/m2. All analyses gave a range of deposited graphite from 0.12 to 52.6 mg/m2. The maximum value was observed at a site located 9 km west of the Chernobyl NPP. The results of the study indicate the importance of studying the upper layer of soil (05 cm) in addition to the lower layer of forest litter.
    • Climate in the Great Lakes Region Between 14,000 and 4000 Years Ago from Isotopic Composition of Conifer Wood

      Leavitt, Steven W.; Panyushkina, Irina P.; Lange, Todd; Wiedenhoeft, Alex; Cheng, Li; Hunter, R. Douglas; Hughes, John; Pranschke, Frank; Schneider, Allan F.; Moran, Joseph; et al. (Department of Geosciences, The University of Arizona, 2006-01-01)
      The isotopic composition of ancient wood has the potential to provide information about past environments. We analyzed the d13C, d18O, and d2H of cellulose of conifer trees from several cross-sections at each of 9 sites around the Great Lakes region ranging from ~4000 to 14,000 cal BP. Isotopic values of Picea, Pinus, and Thuja species seem interchangeable for d18O and d2H comparisons, but Thuja appears distinctly different from the other 2 in its d13C composition. Isotopic results suggest that the 2 sites of near-Younger Dryas age experienced the coldest conditions, although the Gribben Basin site near the Laurentide ice sheet was relatively dry, whereas the Liverpool site 500 km south was moister. The spatial isotopic variability of 3 of the 4 sites of Two Creeks age shows evidence of an elevation effect, perhaps related to sites farther inland from the Lake Michigan shoreline experiencing warmer daytime growing season temperatures. Thus, despite floristic similarity across sites (wood samples at 7 of the sites being Picea), the isotopes appear to reflect environmental differences that might not be readily evident from a purely floristic interpretation of macrofossil or pollen identification.
    • Coastal Upwelling and Radiocarbon—Evidence for Temporal Fluctuations in Ocean Reservoir Effect off Portugal During the Holocene

      Monge Soares, António; Alveirinho Dias, João M. (Department of Geosciences, The University of Arizona, 2006-01-01)
      This paper focuses on the use of the radiocarbon content of marine shells collected along the Portuguese coast as a proxy for the intensity of coastal upwelling off of Portugal. Differences in the 14C ages of closely associated marine mollusk shells and terrestrial material (charcoal or bones) from several Portuguese archaeological contexts seem to be significant throughout the Holocene. Delta-R values range from 940 +/50 to 160 +/40 14C yr. Five of these values are significantly higher than the modern value (250 +/25 14C yr), while the remaining values are lower. The modern value was calculated by measuring the 14C content of live-collected, pre-bomb marine mollusk shells. This value is in accordance with an active upwelling of strong intensity that currently occurs off of Portugal. Some primary observations based on data presented here can be made: i) during the Holocene important changes have occurred in the ocean reservoir effect off the Portuguese coast; ii) these fluctuations may be correlated with regional oceanographic changes, namely with changes in the strength of coastal upwelling; and iii) these changes suggest some sort of variability of the climatic factors forcing coastal upwelling off of Portugal.
    • Comments on Sveinbjörnsdóttir et al. (2004) and the Settlement of Iceland

      Olsson, Ingrid U. (Department of Geosciences, The University of Arizona, 2006-01-01)
      Radiocarbon dates on samples aimed to date the settlement of Iceland are given together with comments by the laboratory, since many of the results and descriptions given by Sveinbjörnsdóttir et al. (2004) in Radiocarbon, together with new results, are in error. The intention of this paper is to present correct dates and further relevant information regarding samples used earlier and to discuss possible complications inherent in the method of Sveinbjörnsdóttir et al. (2004). Examples are given of how critical the collection, treatment, and interpretation of samples may be. An age difference between birch charcoal and grains for a site is expected due to various reasons. If the difference amounts up to ~100 yr, as reported by Sveinbjörnsdóttir et al. (2004), it must only to a small degree be due to biological age. Reference to an excavation report, details regarding stratigraphy, and discussions of the risk for displacement and contamination are missing in their paper. A final evaluation of the time for settlement should not be done until more research is completed and other possible or earlier suggested or even dated sites are discussed. A summary is given of the research on the island and volcanic effects on the 14C activity of the atmospheric CO2, especially over Iceland.
    • Comment On “Diet-Derived Variations in Radiocarbon and Stable Isotopes: A Case Study from Shag River Mouth, New Zealand”

      Beavan Athfield, Nancy (Department of Geosciences, The University of Arizona, 2006-01-01)
    • Dilemma of Dating on Lacustrine Deposits in an Hyperarid Inland Basin of NW China

      Zhang, H. C.; Ming, Q. Z.; Lei, G. L.; Zhang, W. X.; Fan, H. F.; Chang, F. Q.; Wünnemann, B.; Hartmann, K. (Department of Geosciences, The University of Arizona, 2006-01-01)
      Conventional and accelerator mass spectrometry (AMS) radiocarbon, TL, OSL, and IRSL dating results on samples from the cores D100 and I70 from Ejina Basin, one of the most important inland basins in arid-hyperarid NW China, show that it is difficult to determine the ages of sediments at different depths. AMS ages of core D100 samples demonstrate that the sediments at depths from 10 to 90 m were formed between 14 to 30 kyr BP. The inverted ages from both the D100 and I70 cores imply that there was a strong reworking of the sediments during and after deposition processes. The inverted ages also indicate drastic fluctuations of groundwater bearing soluble organic matters, which might be related to neotectonic activities and climate changes during the period. Consequently, it is impossible to establish an accurate and reliable chronology for the cores based only on these dates. All AMS ages, if they are reliable and acceptable, indicate a high deposition rate (5~8 mm/yr), and since all TL, OSL, and IRSL ages are much older than those given by AMS, it makes these methods questionable for determining the ages of lacustrine-fluvial-alluvial deposits.
    • Southern Palestinian Chronology: Two Radiocarbon Dates for the Early Bronze Age at Tell El-Hesi (Israel)

      Anderson, Roger W. (Department of Geosciences, The University of Arizona, 2006-01-01)
      Several articles reporting radiocarbon dates of Early Bronze Age (EB) material from excavations in the southern Levant have been published over the last 30 yr. The excavations conducted at Tell el-Hesi have produced material from which 2 additional 14C dates have been extracted to date. The 2 samples confirm the EB dating of Field VI material and suggest EB III settlement at Hesi might be earlier than previously reported based on pottery typology.
    • Seoul National University Accelerator Mass Spectrometry (SNU-AMS) Radiocarbon Date List I

      Kim, J. C.; Youn, M. Y.; Kim, I. C.; Park, J. H.; Song, Y. M.; Kang, J.; Cheoun, M. K. (Department of Geosciences, The University of Arizona, 2006-01-01)
      The accelerator mass spectrometry facility at Seoul National University (SNU-AMS) began functioning in December 1998 and was first reported at the Vienna AMS conference in October 1999 and at the 17th International Radiocarbon Conference in Israel in June 2000. At the Vienna conference, we reported our accelerator system (Kim et al. 2000) and details of the basic sample preparation system (Lee et al. 2000), such as the combustion line to produce CO2 ; the catalytic reduction line for the graphitization of CO2 ; and the pretreatment procedures for wood, charcoal, and peat samples. The recent progress of the AMS facility (Kim et al. 2001) and the extension of the sample pretreatment system to iron and bone samples were reported at the 17th International Radiocarbon Conference (Cheoun et al. 2001). In the meantime, extensive testing of accuracy and reproducibility has been carried out, and ~1000 unknown archaeological and geological samples have been measured every year. In this report, the archaeological, geological, and environmental data carried out in 1999 are presented in terms of yr BP.
    • Seoul National University Accelerator Mass Spectrometry (SNU-AMS) Radiocarbon Date List II

      Kim, J. C.; Youn, M. Y.; Kim, I. C.; Park, J. H.; Song, Y. M.; Kang, J. (Department of Geosciences, The University of Arizona, 2006-01-01)
      The accelerator mass spectrometry facility at Seoul National University (SNU-AMS) began functioning in December 1998 and was first reported at the Vienna AMS conference in October 1999 and at the 17th Radiocarbon Conference in Israel in June 2000. At the Vienna conference, we reported our accelerator system (Kim et al. 2000) and the basic sample preparation system (Lee et al. 2000), including the combustion line to produce CO2 ; the catalytic reduction line for the graphitization of CO2 ; and also pretreatment procedures for wood, charcoal, and peat samples. Recent progress of the AMS facility (Kim et al. 2001) and extension of the sample pretreatment system to iron and bone samples were reported at the 17th Radiocarbon Conference (Cheoun et al. 2001). In the meantime, extensive testing of accuracy and reproducibility has been carried out, and ~1000 unknown archaeological and geological samples have been measured every year. A report of data carried out in 1999 is presented by Kim et al. (this issue). In this report, the archaeological, geological, and environmental data carried out in 2000 are presented in terms of yr BP.
    • Society Islands (Central Eastern Polynesia) Chronology: 11 Radiocarbon Dates for the Late Prehistoric Expansion and Proto-Historic Periods in the Opunohu Valley, Moorea

      Kahn, Jennifer G. (Department of Geosciences, The University of Arizona, 2006-01-01)
      The chronology of residential site construction and occupation in the upper reaches of the Opunohu Valley, Moorea, Central Eastern Polynesia, has been debated over the last 15 yr. This paper reports a suite of 11 radiocarbon age determinations from excavations at 5 house sites and a simple temple structure (marae). Direct accelerator mass spectrometry (AMS) dating of wood charcoal identified to short-lived taxa confirms site construction and occupation during the mid-15th to 17th centuries, supporting that maximal population density was in the centuries immediately prior to European contact. The study demonstrates that targeted dating of multiple structures within residential complexes allows for multiple phases of site construction and use to be discriminated. These data are critical for adequately assessing site contemporaneity and the development, maintenance, and expansion of residential groups and their house clusters through time.
    • Testing the Limits: Radiocarbon Dating and the End of the Late Bronze Age

      Hagens, Graham (Department of Geosciences, The University of Arizona, 2006-01-01)
      Archaeometry is becoming an increasingly important tool in chronological research related to events in the Ancient Near East during the 2nd millennium BCE. This paper is a review of recently published radiometric results in an attempt to establish the probable dating range for one particular event that occurred during the last quarter of that millennium, the end of the Late Bronze Age. The conclusion is that in spite of significant improvements in methodology in recent years, the quantity and quality of radiocarbon data are still insufficient to define the range of that date to much better than a century. It is concluded that the most likely date of the Late Bronze/Iron Age transition (here defined by the arrival of Mycenaean LH IIIC:1b pottery in the Levant) is somewhere in the 8-decade range between ~1170 to 1100 BCE. A comparative study of archaeological and historical evidence would appear to favor the lower value.
    • Letter to the Editor

      Harbottle, Garman (Department of Geosciences, The University of Arizona, 2006-01-01)
    • The 3MV Multi-Element AMS in Xi'an, China: Unique Features and Preliminary Tests

      Zhou, Weijian; Zhao, Xiaolei; Xuefeng, Lu; Lin, Liu; Zhengkun, Wu; Peng, Cheng; Wengnian, Zhao; Chunhai, Huang (Department of Geosciences, The University of Arizona, 2006-01-01)
      A 3MV multi-element accelerator mass spectrometer (AMS) has been installed in Xian, China, and preliminary tests have been completed. The results of both background and precision tests for 4 nuclides are 3.1 x 10^-16, 0.2% (14C); 1.8 x 10^-14, 1.4% (10Be); 2.3 x 10^-15, 1.14% (26Al); and 2.0 x 10^-14, 1.75% (129I). The unique features of this facility are the newly developed ion source accepting solid and CO2 samples; the specially designed low-energy injector, including a beam blanking unit and Q-snout; the acceleration tube structure with the combined magnetic and electrostatic suppression; and the function of the slit stabilization in the post-acceleration system. These features are discussed in terms of the end-users point of view.
    • Radiocarbon Determination of Particulate Organic Carbon in Non-Temperated, Alpine Glacier Ice

      Steier, Peter; Shah, Sunita R.; Drosg, Roswitha; Pearson, Ann; Fedi, Mariaelenea; Kutschera, Walter; Schock, Martin; Wagenbach, Dietmar; Wild, Eva Maria (Department of Geosciences, The University of Arizona, 2006-01-01)
      Dating ice samples from glaciers via radiocarbon is a challenge that requires systematic investigations. This work describes an approach for extraction and accelerator mass spectrometry (AMS) 14C analysis of the particulate organic carbon (POC) fraction in glacier ice samples. Measurements were performed at VERA (Vienna Environmental Research Accelerator) on ice samples obtained mainly from the non-temperated ablation zone of the Grenzgletscher (Grenz Glacier) system (Monte Rosa Massif, Swiss Alps). The samples were obtained from 2 sampling sites situated roughly on a common flow line. The sample masses used were between 0.3 and 1.4 kg of ice, yielding between 18 and 307 micrograms of carbon as POC. The carbon contamination introduced during sample processing varied between 5.4 and 33 micrograms C and originated mainly from the quartz filters and the rinsing liquids used in processing. Minimum sample sizes for successful graphitization of CO2 in our laboratory could be reduced to <10 micrograms carbon, with a background in the graphitization process of ~0.5 micrograms of 40-pMC carbon. Evaluation of the whole procedure via 11 Grenzgletscher samples revealed a surprisingly large scatter of pMC values. We obtain a mean calibrated age of 2100 BC to AD 900 (95.4% confidence level), which is not significantly different for the 2 sampling sites. Discussions of these results suggest that single 14C dates of glacial POC are presently of limited significance. Future improvements with respect to analytical precision and sample characterization are proposed in order to fully explore the POC dating potential.
    • 14C Dating of ~2500-Yr-Old Choukai Jindai Cedar Tree Rings from Japan Using Highly Accurate LSC Measurement

      Sakurai, Hirohisa; Kato, Wataru; Takahashi, Yosuke; Suzuki, Kayo; Takahashi, Yui; Gunji, Shuichi; Tokanai, Fuyuki (Department of Geosciences, The University of Arizona, 2006-01-01)
      Radiocarbon ages of 8 decadal tree rings and 66 single-yr tree rings have been measured with a highly accurate liquid scintillation counting (LSC) system (0.2% error) after synthesizing 10.5 g of benzene for each a-cellulose sample produced from tree rings of Choukai Jindai cedar in Japan (39 degrees N). The 14C ages were between 2449 and 2539 14C yr BP for the 21 samples. From the wiggle-matching of the data set using the IntCal04 (Reimer et al. 2004) calibration data in OxCal v 3.10 (Bronk Ramsey 2005), the estimated age of the outer edge of the Choukai tree rings was 477.5 BC (+/12.5 yr) with a confidence level of 95.5%; hence, the Choukai tree rings range from 2757 to 2437 cal BP. The age indicates an improved eruption date of the Choukai Volcano. The statistical errors at 1 sigma are approximately +/10 and +/7 14C yr for the 5-yr data and the decadal data from the single-yr measurements, respectively. For the interval between 2580 and 2520 cal BP, it is statistically significant that the Choukai 14C ages are ~16 14C yr older on average than both the IntCal04 and QL German oak (~50 degrees N) data sets. The ~2.0 offset is informative for the study of regional offset in the Far East.
    • A Direct Method to Measure 14CO2 Lost by Evasion from Surface Waters

      Billett, M. F.; Garnett, M. H.; Hardie, S. L. (Department of Geosciences, The University of Arizona, 2006-01-01)
      Recent methodological advances in the use of zeolite molecular sieves for measuring the isotopic signature of CO2 have provided the opportunity to make direct measurements of 14CO2 in various field situations. We linked a portable molecular sieve/pump/IRGA system to a floating chamber to demonstrate the potential of the method to quantify the isotopic signature (d13C and 14C) of CO2 lost by evasion (outgassing) from surface waters. The system, which was tested on a peatland stream in Scotland, involved 1) an initial period of scrubbing ambient CO2 from the chamber, 2) a period of CO2 build-up caused by surface water evasion, and 3) a final period of CO2 collection by the molecular sieve cartridge. The field test at 2 different sites on the same drainage system suggested that the results were reproducible in terms of d13C and 14C values. These represent the first direct measurements of the isotopic signature of CO2 lost by evasion from water surfaces.
    • In Memoriam: Henry N. Michael (1912-2006)

      Department of Geosciences, The University of Arizona, 2006-01-01
    • Dating Paleosol and Animal Remains in Loess Deposits

      Zhang, H. C.; Li, B.; Yang, M. S.; Lei, G. L.; Ding, H.; Niu, Jie; Fan, H. F.; Zhang, W. X.; Chang, F. Q. (Department of Geosciences, The University of Arizona, 2006-01-01)
      Accurate and reliable dating of paleosols, animal remains, and artifacts is of crucial importance in reconstructing environmental change and understanding the interrelationship between human activities and natural environments. Dating different materials in the same sample can help resolve problems such as soil carbon sources and carbon storage state. Conventional radiocarbon dating of soil (inorganic and organic matter) and accelerator mass spectrometry (AMS) dating of animal remains (fossil bones and teeth) result in different ages for materials from the same sample position in a typical loess section at Xinglong Mountain, Yuzhong County, Gansu Province in NW China. Inorganic matter is ~3400 yr older than organic matter, 4175 +/175 cal BP to 3808 +/90 cal BP. A 1610-yr difference between the 14C ages of fossils (animal bones and teeth) and soil organic matter suggests that a depositional hiatus exists in the studied profile. The varying 14C ages of fossils and soil organic and inorganic matter have important implications for paleoclimate reconstructions from loess sections. It is critical to consider the meaning of the variable 14C ages from different material components from the same sample position in terms of soil organic and inorganic carbon storage, vegetation history reconstruction, archaeology, and the study of ancient civilizations.
    • Determination of 90Sr/90Y in Wheat Grains, Soil, and Deposition Samples by TBP Extraction and Cerenkov Counting

      Gertmann, Udo Ch; Tschöpp, Vlasta (Department of Geosciences, The University of Arizona, 2006-01-01)
      Within the framework of radioecological studies, 90Sr was determined in wheat grains, soil, and deposition samples. The radiochemical purification of 90Y consisted of liquid-liquid extraction by tributyl phosphate (TBP), followed by hydroxide and oxalate precipitations and, if necessary, the removal of thorium by anion exchange chromatography. The procedure proved to be very robust and reliable, having yttrium yields of 92.7 4.6% for 1-kg wheat samples, 90.9 4.2% for 50-g soil samples, and 90.6 3.2% for wet and dry deposition samples. 90Y was determined by Cerenkov counting and proportional counting. By optimizing the Cerenkov counting window, a figure of merit (FOM) of 4750 could be reached using a Quantulus 1220 system. Minimum detectable activities were in the range of 10 mBq.
    • Response to Beavan Athfield's “Comment on ‘Diet-Derived Variations in Radiocarbon and Stable Isotopes: A Case Study from Shag River Mouth, New Zealand’”

      Anderson, A.; Higham, Thomas (Department of Geosciences, The University of Arizona, 2006-01-01)
      Beavan Athfield (2006) has commented on our recent paper in this journal (Higham et al. 2005). In our opinion, both in her response and in Beavan Athfield (2004) she misrepresents the evidence and conclusions presented by Anderson (2000). She claims (Beavan Athfield 2006:117) that Andersons (2000) Figure 6, which is reproduced as Beavan Athfields (2004) Figure 1, shows that ages of ancient rat bone gelatin in 1995-1996 (NZA numbers 4000-6000) were exclusively earlier than about 1000 BP, while those from 1997 onward (NZA numbers 7000+) were exclusively later than about 1000 BP. Beavan Athfield asserts that this is the result of Anderson (2000) ignoring 9 published accelerator mass spectrometry (AMS) results from 1995-1996 that were younger than about 900 BP. These would be serious claims of poor scholarship, were they substantiated, but in fact, Anderson (2000, 2004) never asserted that the AMS results were distributed so exclusively, nor did he fail to take account of all published results.