A few of our colleagues, upon receiving a radiocarbon date younger than they expected, have wondered if X-rays in airport security devices might have increased their 14C content. Unfortunately for them, our colleagues have been forced to find alternate explanations for the uncooperative dates. Airport X-rays simply cannot produce 14C. However, a new security technology is almost ready for installation at Kennedy Airport for some international flights, and, according to the Wall Street Journal, 100 additional units are planned for other high-risk airports. The new device will detect high concentrations of nitrogen (a component in explosives) by thermal neutron activation (TNA). Since TNA on a global scale is the process by which nature produces virtually all 14C in the atmosphere, some 14C must be produced in high-nitrogen materials, such as bones, as they pass through a neutron activation airport security device. The question important to the radiocarbon dating community is how much effect can the 14C thus produced have on the 14C date?

Timothy Weiler Linick died on June 4th, 1989. He was a dedicated researcher, and an important part of the NSF Accelerator Facility for Radioisotope Analysis at the University of Arizona. He will be remembered for his care and attention to details, especially in the calculation and reporting of radiocarbon dates. He made important contributions to the fields of oceanography and tree-ring calibration of the 14C time scale.

Edward Smith Deevey, Jr died on November 29, 1988, following a heart attack. He was Graduate Research Curator of Paleoecology at the Florida Museum of Natural History, University of Florida, Gainesville. As a reflection of his expertise in many academic disciplines, Ed held Graduate Research Professorships in four University of Florida departments: zoology, botany, geology and Latin American studies.

The “C14” data base, designed and implemented at the University of Arizona Radiocarbon Dating Laboratory, uses Q&A, an artificial intelligence data file management program. The data entered into this data base are easily retrievable and exportable for submission to RADIOCARBON, and to the International Radiocarbon Data Base (IRDB). The use of artificial intelligence allows both novice and experienced computer operators to search and retrieve data with few key strokes and normal English sentences.

Radiocarbon dating (Libby, 1955) has been an important tool in the marine sciences since the early 1950s (eg, Arrhenius, Kjellberg & Libby, 1951; Ericson et al, 1956; Broecker, Ewing & Heezen, 1960; Emery & Bray, 1962) and the basic principles and analytic procedures of the method have changed little. In the late 1970s, the Accelerator Mass Spectrometer (AMS) method of 14C dating was developed (Bennett et al, 1977, 1978), the major advantages being that samples several thousand times smaller than needed for beta-decay counting can be dated, and analysis time is reduced to ca 1 hr from the 1–6 days needed for beta-decay methods.

Modern bone contains ca 25% protein material, most of which is collagen. Amino acids separated from collagen isolated from bone are suitable for 14C dating of fossil bone, but attempts to carry out this procedure on bones seriously depleted in protein can yield erroneous 14C dates. Amino-acid analysis of fossil bone gives quantitative information on the degree of preservation of its organic component. Also, the relative abundance of the amino-acid components reveal the degree to which the collagen-like pattern has been altered. Alteration may be caused by addition of extraneous material. A 1mg sample of bone material is sufficient for this preliminary analysis. We have developed a series of acceptance criteria for whether a particular specimen is likely to yield the correct 14C age. 14C dating of fossil bones not seriously depleted in protein is a straightforward procedure and yields reliable dates.

Many 14C dating laboratories have established that coal samples exhibit a finite 14C age, apparently caused by contamination of the specimens before any laboratory preparation is undertaken. In this work, the possibility that the contamination is due to microbial and fungal activity in the coal substrate is considered and some suggestions are made for alternative sources of background test materials for 14C dating laboratories. Initial results indicate that geologically formed graphites contain little 14C and are likely to be good background test materials, especially in 14C AMS laboratories.

Collagen-based pretreatment methods for bone yield inconsistent results for those samples where protein preservation is low, as frequently found in bones from the semi-arid zones of Australia and North America. New methods for dealing with low collagen bones are needed, and this paper suggests that the non-collagenous proteins, particularly the blood proteins, may offer advantages for AMS dating because of their better preservation. Amino-acid profiles of collagen and non-collagenous proteins suggest that such differential preservation may be due to physico-chemical differences, and help to explain the poor results from dating low-collagen bones.

The Samoan Archipelago occupies a critical position for understanding the dispersal of early Austronesian-speaking peoples into the southwestern Pacific, including the initial colonization by humans of the Polynesian triangle. To date, the most easterly reported site of the Lapita cultural complex (Green, 1979; Kirch, 1984; Kirch & Hunt, 1988) is the Mulifanua site on Upolu Island, Western Samoa (Green & Davidson, 1974). Lapita colonists settled the larger, western Samoan Islands by the end of the second millennium bc. Archaeologic and linguistic evidence also suggest that the islands of Eastern Polynesia (eg, Marquesas, Society and Cook Islands) were settled, at least in part, from Samoa. However, the timing of this movement into Eastern Polynesia has not yet been dated to earlier than ca 150 bc on the basis of radiocarbon dating of cultural materials from the Marquesas Islands (Kirch, 1986; Ottino, 1985). This has raised the issue of whether there was a “long pause” between the settlement of Samoa (and the other islands of Western Polynesia, such as Tonga, Futuna, and ‘Uvea) and that of Eastern Polynesia (Irwin, 1981; Kirch, 1986; Terrell, 1986).

The importance of chronometric dating in archaeology cannot be overemphasized. Indeed, most chronologies developed throughout the world during the past three decades have depended on radiocarbon age determinations to provide a temporal framework for examining change over time in cultural sequences during the late Pleistocene and Holocene. With the advent of legislation in the mid-1960s designed to protect archaeological sites in the United States threatened by increased urban development or government sponsored projects, archaeological surveys and excavations were mandated as a means for preserving information otherwise destroyed. As a result, thousands of projects have contributed to a growing body of “gray literature,” ie, unpublished proprietary or manuscript reports with very limited circulation. Within these reports are hundreds, if not thousands, of 14C age determinations, most of which are not accessible in published form. One objective of this paper is to present all the 14C age determinations for the island of Moloka'i, Hawai'i as of December 1988, including 41 dates never before published with stratigraphic details.

A semi-automated continuous-flow system used to process archaeological bone to purified gelatin or amino acids for 14C dating is described. Powdered bone is retained in flow cells specifically designed to permit the sequential leaching of the bone with acid, alkali and water. Crude collagen obtained by this process is gelatinized, and than either purified directly using a macroporous cation exchange resin (BioRad AGMP-50), or hydrolyzed and the amino acids desalted on BioRad 50W-X8 resin. When compared with previous methods used by the laboratory, the new method allows more samples to be treated to a higher degree of purification. Examples of dates obtained on “standard” bones are presented, and confirm that no contamination is introduced from the components used in the new process.

The following list consists of dates obtained by liquid scintillation counting of benzene for archaeologic samples mostly measured between June 1986 and June 1987.

Radon gas is a serious contaminant in radiocarbon dating by radiometry. The low specific ionizations associated with the α-particle emitting radon and its β-particle emitting daughters overlap within the 14C counting window. Elimination of radon is therefore imperative for precise 14C age determinations. This paper deals with the sources and mechanism of incorporation of radon affecting 14C dating by liquid scintillation (LS) counting, and reviews conventional radon elimination practices in 14C laboratories. It demonstrates, based on rigorous multichannel and multiparameter α- and β-particle spectral analyses of some 1000 benzene samples, that parent radium is not present and that its daughter radon is quantitatively eliminated during dynamic vacuum recovery of benzene at −78°C. However, the radon-free benzene can be recontaminated by exposure to air containing traces of radon, such as is common in concrete or low-lying laboratories. The use of radon-free air, when exposing the benzene to the atmosphere, and the monitoring of radon counts from the environment and sample benzene in a fixed ‘radon window', are essential prerequisites to the quality control of 14C age determinations in very low background systems.

The Krakow Radiocarbon Laboratory is part of the Environmental Physics Department headed by T Florkowski and belongs to the Institute of Physics and Nuclear Techniques, The Academy of Mining and Metallurgy. A 3H and 14C laboratory was built primarily for the assessment of natural radioactivity in groundwater. In 1982, 14C preparation facilities were extended to include a combustion system for organic samples. The 14C measurement method is liquid scintillation counting on synthesized benzene in an LSC spectrometer TRI-CARB model 3320 (Packard International).