At a time when exchange between scientific and non-scientific disciplines was uncommon, Willard F Libby broke through conventional barriers. Early influences prepared him for a career marked by its interdisciplinary approach, and for a discovery with far-ranging applications to many diverse branches of knowledge.

Diet can play a significant role in anomalous radiocarbon ages derived from bone and other tissues when the food web incorporates depleted 14C reservoirs, such as the marine environment. Dietary effects from a post-bomb carbon variation have also been found in modern invertebrates and populations of Rattus exulans (Beavan and Sparks 1998). We now present the effect on absolute percent modern (pMC) and the conventional radiocarbon age (CRA) of a modern aquatic/terrestrial food web in a volcanic zone of the North Island, New Zealand. At Lake Taupo, geothermal venting transfers 14C depleted carbon to lake waters, which aquatic plants fix into the food chain; depleted 14C is shown to then pass on to shellfish, waterfowl, and Norway rat (Rattus norvegicus). The geothermally induced 14C variations from modern atmospheric pMC and CRA can increase apparent 14C ages by >2000 years.

We show that high-precision radiocarbon (Δ14C) measurements from annual bands of a Hawaiian surface coral decreased by 7‰ from AD 1893 to 1952. This decrease is coincident with the Suess Effect, which is mostly due to the dilution of natural levels of 14C by 14C-free fossil fuel CO2. This decrease is equal to that expected in surface waters of the subtropical gyres, and indicates that the surface waters of the North Pacific were in steady state with respect to long term mixing of CO2 during the past century. Correlation between Δ14C and North Pacific gyre sea surface temperatures indicates that vertical mixing local to Hawaii and the North Pacific gyre as a whole is the likely physical mechanism to result in variable Δ14C. Prior to 1920, this correlation starts to break down; this may be related to the non-correlation between biennial Δ14C values in corals from the southwest Pacific and El Niño events observed during this period as well.

Radiocarbon age determinations of wood charcoal are commonly used to date past forest fire events, even though such ages should be greater than the fire event due to the age of the wood at the time of burning. The difference in the 14C-derived age of charcoal and the time-since-fire (the “inbuilt age”) may be considerable in some vegetation types and thus must be estimated before interpreting fire dates. Two methods were used to estimate the potential range of inbuilt age of soil charcoal dated to determine ages of forest fires on the west coast of Vancouver Island (Canada). First, 26 14C ages on charcoal in surficial soil were compared directly with ages of forest fire determined by tree-ring counts, suggesting inbuilt ages of 0–670 years. Second, a simulation model that uses estimated fuel loads, fuel consumption, charcoal production, and the ages of charred wood (time since wood formation), suggests that the combination of slow growth rates and slow decay rates of certain species can account for inbuilt ages of more than 400 years in this forest type. This level of inbuilt age is large enough such that the actual age of a fire may not occur within the 2σ confidence interval of a calibrated charcoal 14C age determination, and thus significantly affect the interpretation of fire dates. A method is presented to combine the error of a calibrated 14C age determination with the error due to inbuilt age such that the larger adjusted error encompasses the actual age of the fire.

Lynch's Crater in northeastern Australia provides a long, continuous record of environmental change within the Late Quaternary. Here, we present newly determined radiocarbon ages, using acid-base-acid stepped combustion (ABA-SC) and acid-base-wet oxidation stepped combustion (ABOX-SC) pretreatment strategies. The new results largely confirm the original untreated radiocarbon results for the uppermost 9 m of sediments, (ca. 35 ka BP). Below this depth, results from both pretreatment methods are in stratigraphic agreement and extend the dating of the record from 38 ka BP to about 48 ka BP, although an apparent increased sedimentation rate below 12 m is questionable. The scarcity of “charcoal” in several of the samples raises questions regarding the application of ABOX-SC to lake or swamp sediments, with evidence for contributions from younger, chemically resistant bacterial carbon along with fine “charcoal” in some samples. However, the extent to which this phenomenon is significant to the final age estimate appears to be sample specific, and is probably dependent upon the length of the wet oxidation step in the pretreatment.

The chronology study of the cemetery of Marquises of Jin is valuable to improving the chronological table of Marquis of Jin family. It is also helpful for improving the chronological table of the Zhou Dynasty. The samples were measured at Peking University (PKUAMS). We also made an interlaboratory check with Isotrace to ensure the accuracy. By careful analysis of archaeological information, we built different models and calibrated by OxCal. The calibration results, both sampling contexts and estimations, are in very good agreement with the historical record. Because the dates of some events correspond to the special part of the curve, the calibration gets very high precision. The calibration result of tomb M93 suggests that its host is Marquis Shangshu instead of Marquis Wen.

The Mulifanua ferry berth has the distinction of being the only site in Samoa with dentate-stamped Lapita wares, and is the most easterly Lapita site in the Pacific. Two new radiocarbon determinations of material associated with Lapita pottery found at Mulifanua are presented. The accuracy of this data is evaluated according to the results of recent reassessment of pottery from the site, and current theories regarding the age of Lapita settlement in the eastern Pacific. The resulting calibrated radiocarbon ages put occupation of the Mulifanua Lapita site at around 2880–2750 cal BP (930–800 BC). This conclusion is in agreement with the pottery chronology and supports recent hypotheses of rapid Lapita settlement in the Fiji/Tonga region around 2850–2700 cal BP (900–750 BC).

A date of 4300 ± 90 BP for extinct megafauna in Argentina is discussed. The fossil remains come from the Guerrero Member (area) of the Luján Formation near the city of Luján, Buenos Aires Province. The age of the top of the Guerrero Member is constrained by more than 60 radiocarbon dates obtained from the overlying Río Salado Member of Luján Formation, Las Escobas Formation, and Puesto Callejón Viejo Soil, most of them older than 4300 BP. In view of its low collagen content, the 14C measurement of bone sample from Luján should not be accepted uncritically. Because of the poor bone preservation and the possible introduction of “young” contaminants that were not completely eliminated, the 14C date of 4300 ± 90 BP is not reliable. Both biostratigraphic and 14C dating evidence indicates that the date of 4300 BP for the last representative of extinct megafauna in South America is unsupported.

The glyptodont (Glyptodontidae Burmeister 1879, in Ameghino 1889), a giant cousin of the armadillo, has long been thought to have disappeared in South America at least 10,000 years ago at the end of the Pleistocene. There are indications that the glyptodont had some interaction with ancient hunter-gatherers peoples (Politis et al. 1987; Politis 1995), but the precise time of its extinction has never been well established. Most recently, a brief mention of 14C dates of 7500 to 6500 BP (Geotimes 1996) for glyptodont remains discovered at La Moderna (Azul Department, Buenos Aires province, Argentina), has aroused excitement because the new younger dates have changed the traditional idea about the survival and extinction of this beast.

Several single-piece shell fishhooks from CA-SRI-43 on Santa Rosa Island were dated by association to roughly 5500 cal BP and were argued to be among the oldest specimens in the region. Direct accelerator mass spectrometry (AMS) radiocarbon dating of one of these hooks provided a date of 560 cal BP, however, making it about 5000 yr younger than originally presumed. This younger date is more consistent with the regional shell fishhook chronology and demonstrates the importance of obtaining direct AMS 14C dates to refine artifact and site chronologies.

Smoothed curves are least-squares fitted to three sets of decadal radiocarbon calibration data from New Zealand and British Isles (AD 1725–1935) and western North America (AD 1145–1945). The curves are compared with each other and with a curve previously calculated from New Zealand data (AD 1335–1745). The smoothing procedure results in reduced standard deviations of the curves, but at the expense of time resolution. The comparison shows a variable 14C offset between the northern and southern hemispheres of 0–70 years (Southern Hemisphere older), and a Northern Hemisphere longitudinal variation of −20 to +60 years (British Isles generally older than western North America).

The purpose of a reservoir offset is to enable the application of calibration data (μ(θ), e.g. Stuiver et al. 1998) developed for one reservoir (primary reservoir) to CRAs from another (secondary reservoir), for example the use of a hemispheric offset for terrestrial samples (Barbetti et al. 1995; McCormac et al. 1998; Sparks et al. 1995; Vogel et al. 1986, 1993). The usual approach has been to define the activity of the secondary reservoir as some form of constant offset (with error) from the primary reservoir (e.g. Higham and Hogg 1985; McFadgen and Manning 1990). In this case, all CRAs from a secondary reservoir are given the same offset. The value of this common offset is not known exactly, but any uncertainty in the measured value of the offset corresponds to uncertainty in the common offset for all CRAs. However, the standard procedure for incorporating offset error into CRAs incorrectly allows a different offset for each CRA. The offset for each CRA is incorrectly allowed to vary by the measurement error reported for the offset value. Technically, the offset is incorrectly treated as varying independently from one CRA to the next, when in fact it is a single parameter for the secondary reservoir in question. In light of this, the calibrated date distributions will be incorrect for CRAs where an offset has been applied and the standard approach to offset error treatment has been used. In many cases, the differences between correct and incorrect calibrated date distributions will be insignificant. However, in some cases significant differences may arise and other approaches to treating the error associated with offsets need to be adopted.

The first measurements of the fluorescence of liquid organic compounds after excitation with nuclear radiation were published 1948 in a thesis of L Herforth and a paper by Herforth and Kallmann (1949).

Some fragments of the Dead Sea Scroll manuscripts were contaminated with castor oil in the late 1950s. We have conducted experiments in order to establish if the AAA pretreatment cleaning procedures conducted on Dead Sea Scroll manuscript samples in the last two dating series (Bonani et al. 1992; Jull et al. 1995) were effective in removing oil contamination. Our experiments show that not all oil contamination can be expected to have been removed by the acid-alkaline-acid (AAA) pretreatment, and that the radiocarbon ages previously reported therefore cannot be guaranteed to be correct. Any samples contaminated with castor oil were most likely reported with ages that are too young by an unknown amount.

Ostrich eggshell from archaeological sites remains largely free of more recent carbon contamination and as such is suitable material for radiocarbon dating. The carbonate fraction of the shell does, however, display an initial deficit in 14C, which causes the ages to appear 180 ± 120 yr too old.

The 47th Annual Conference on Bioassay, Analytical & Environmental Radiochemistry. 3–8 November 2001, Honolulu, Hawaii. The conference will consist of a series of vendor workshops and displays, oral presentations, and technical workshops. Abstracts are due by 15 July 2001. A limited number of abstracts will be assigned to oral sessions. For more information, contact Bill Burnett (wburnett@mailer.fsu.edu) or Kenneth G W Inn (kenneth.inn@nist.gov).