An ancient pottery workshop belonging to the Han Dynasty was excavated in Caoxie village, Hepu County. Caoxie village is an important archaeological site in Hepu County, Beihai City, in south China's Guangxi Zhuang Autonomous Region. It is believed that Hepu County was the oldest departure point on the ancient maritime trading route during the Han Dynasty (206 BC to AD 220) due to the ideal natural geographical conditions and the existence of a large number of Han tombs. Radiocarbon measurements on wood and charcoal samples from the Caoxie village site were performed at the Peking University AMS facility (PKU-AMS), Beijing, and the Centre for Isotopic Research for Cultural and Environmental Heritage (CIRCE) at Naples Second University, Italy. Calibrated ages were obtained with code CALIB 5 (Stuiver and Reimer 1993). The results of these measurements are presented and the related chronology is discussed.

We report radiocarbon dates for ∼150 archaeological sites in Korea belonging to the Neolithic-Bronze Age transition period. From the present compilation, we find that the Neolithic-Bronze Age transition in Korea started as early as ∼2300 BC and continued over the course of 800–900 yr with peaks representing population increases occurring 2–3 times. Compared with cases in other regions of the world, the Neolithic-Bronze Age transition in Korea was similar in both magnitude and transition time. However, the process in Korea appears to have occurred about 2000 yr later. Further, we find that the attempt to explain the Neolithic-Bronze Age transition in Korea as a migration hypothesis based only on a sudden population increase is not tenable.

New ΔR values are presented for 10 known-age shells from the Kimberley region of northwest Australia. Previous estimates of ΔR for the Kimberley region are based on only 6 individual shell specimens with dates of live collection known only to within 50 yr (Bowman 1985a). Here, we describe the results of our recent attempts to constrain ΔR variability for this region by dating a suite of known-age pre-AD 1950 shell samples from the Australian Museum and Museum Victoria. A regional ΔR of 58 ± 17 14C yr for open waters between Broome and Cape Leveque is recommended based on 7 of these specimens. The criteria used to select shells for dating and inclusion in the regional mean are discussed.

The application of chronometric dating studies in Korean archaeology has lagged behind similar research in China and Japan. The focus of this article is to provide an update on the accelerator mass spectrometry (AMS) radiocarbon dates derived from Korean Paleolithic and Early Neolithic sites. One of the major highlights from recent AMS 14C studies in Korea is that blade (and microblade) technologies may have diffused directly from Siberia, rather than through northern China as originally thought. In addition, a Neolithic wooden boat has been discovered in Korea that is as old as, if not older than, similar discoveries from eastern China. More detailed archaeological and chronometric studies in Korea in the coming years will certainly clarify many of the points mentioned here. In particular, through more detailed studies, we will be able to further evaluate the causal factors that provided the impetus for the Late Paleolithic-Neolithic transition in Korea.

The marine radiocarbon reservoir effect (MRE) occurs as a spatially and temporally dependent variable owing to localized changes in oceanic water composition. This study investigates ΔR values (deviations from the global average MRE whose ΔR = 0) during the period 500–1350 BP for the east coast of Scotland, where a complex estuarine system exists that drains into the semi-enclosed North Sea basin. Due to the availability of suitable archaeological samples, the data set has a distinct Medieval focus that spans the area from Aberdeen in the north to East Lothian in the south. Many of the ΔR values are not significantly different from 0 (the global average), but there are occasional excursions to negative values (max –172 ± 20) indicating the presence of younger water. These values show greater variability compared to other published data for this general region, suggesting that considerable care must be taken when dating marine derived samples from archaeological sites on the east coast of Scotland.

The Mogao Grottoes site at Dunhuang is one of the largest stone cave temples in China. The site features 735 caves with Buddhist mural paintings. To investigate the chronology of early caves of the Mogao Grottoes, radiocarbon dates were measured by accelerator mass spectrometry (AMS) on plant remains collected from 4 caves: 268, 272, 275, and 285. Caves 268, 272, and 275 are regarded (by archaeological analysis) to be the earliest existing caves in the Mogao Grottoes. The fourth cave, 285, features inscriptions on the north wall mentioning the oldest dates of the Chinese Mogao era. Plant materials, taken from the plaster layer of mural paintings and core materials from statues, were collected as samples (n = 11) for AMS 14C dating at Nagoya University. Two samples from cave 275 gave calibrated 14C ages of cal AD 380–430 (1 σ). The other samples resulted in a time interval of cal AD 400–550. The calibrated 14C ages obtained for the samples taken from painted murals and the statues in cave 285 are consistent with the date given by the inscription remaining on the cave's north wall.

We report and compare radiocarbon observations made on 2 meridional oceanographic sections along 150°W in the South Pacific in 1991 and 2005. The distributions reflect the progressive penetration of nuclear weapons-produced 14C into the oceanic thermocline. The changes over the 14 yr between occupations are demonstrably large relative to any possible drift in our analytical standardization. The computed difference field based on the gridded data in the upper 1600 m of the section exhibits a significant decrease over time (approaching 40 to 50‰ in Δ14C) in the upper 200–300 m, consistent with the decadal post-bomb decline in atmospheric 14C levels. A strong positive anomaly (increase with time), centered on the low salinity core of the Antarctic Intermediate Water (AAIW), approaches 50–60‰ in Δ14C, a clear signature of the downstream evolution of the 14C transient in this water mass. We use this observation to estimate the transit time of AAIW from its “source region” in the southeast South Pacific and to compute the effective reservoir age of this water mass. The 2 sections show small but significant changes in the abyssal 14C distributions. Between 1991 and 2005, Δ14C has increased by 9‰ below 2000 m north of 55°S. This change is accompanied overall by a modest increase in salinity and dissolved oxygen, as well as a slight decrease in dissolved silica. Such changes are indicative of greater ventilation. Calculation of “phosphate star” also indicates that this may be due to a shift from the Southern Ocean toward North Atlantic Deep Water as the ventilation source of the abyssal South Pacific.

This study aimed to investigate the paleoenvironment of 2 Medieval archaeological sites, Onigashioya and Ooke, in central Japan, by assemblage analyses of insect fossils preserved in sediments at the sites. In the Onigashioya site located in Mie Prefecture, the sclerites of insect fossils classified as the “village” type were detected, which indicates that human activities, and in particular farming, were taking place there. Rice paddies and fields existed near the site, which explains why many insects harmful to rice plants and crops were detected in the area. The radiocarbon date for sclerite remains of Hydrophilus acuminatus, an aquatic beetle that live in rice paddy fields, was calibrated to be cal AD 1010–1155. Analysis of sclerite remains of Craspedonotus tibialis, a ground beetle that typically inhabits seashore environments, resulted in a date of cal AD 1020–1155. This finding suggests that human settlements existed in the seaside areas of the Onigashioya site in the 11th century AD. In the Ooke site located in Aichi Prefecture, “insect pits” were found, which are structural remains containing a large number of Anomala rufocuprea, an insect that preys on field crops. Farmers would have gathered the insects from the fields and buried the dead remains in the pits. Accelerator mass spectrometry (AMS) 14C dates on sclerite remains of A. rufocuprea ranged from cal AD 1264 to 1385. It should be noted that fruit trees and vegetable crops were planted widely around the site in the 13th century AD. As the result, A. rufocuprea propagated greatly around the site in that period. It is probable that many insects harmful to field crops multiplied largely in this region due to the development of local woods and plains into farming fields. This type of development occurred throughout Japan during the Medieval period.

Radiocarbon was measured in the surface seawater dissolved inorganic carbon (DIC) of the Bay of Bengal during November 2006. A meridional transect of the Δ14C in DIC was obtained from measurements in closely spaced samples collected roughly along 88°E. The Δ14C of these samples ranged from 44‰ to 57.7‰ (mean 51.8 ± 1.1‰, n = 12), and 38‰ at one station in the northern Bay of Bengal. The overall pattern of 14C distribution in DIC of surface Bay of Bengal during 2006 was roughly similar to that during the WOCE expedition of 1995. These results indicate a Δ14C decline rate of ∼4‰ per decade since WOCE in the surface Bay of Bengal, which is much smaller compared to a decline rate of ∼25‰ per decade observed in the 2 decades between the GEOSECS and WOCE expeditions, due to the smaller atmosphere-ocean Δ14C gradient.

Genji monogatari emaki and Ban-dainagon ekotoba are Japanese national treasures. Although the periods in which they were painted have not been accurately determined, radiocarbon dating cannot be applied to these priceless artifacts because of the destructive nature of 14C dating. In this study, the periods of their origin were determined by 14C dating the kohitsugire calligraphy. Kohitsugire are ancient paper sheets containing graceful calligraphy. They originally were part of ancient manuscripts. Two kohitsugire named Imaki-gire and Kingin-kirihaku-wakanroeishu-gire are written in the same style as Genji monogatari emaki and Ban-dainagon ekotoba. Although Imaki-gire and Kingin-kirihaku-wakanroeishu-gire had been attributed to Asukai Masatsune (AD 1170–1221) on the basis of the kiwamefuda certificates, recent calligraphical and paleographical studies suggest that they are genuine handwritings of Fujiwara no Norinaga (AD 1109–1180?). We applied 14C dating by accelerator mass spectrometry (AMS) to Imaki-gire and Kingin-kirihaku-wakanroeishu-gire. The calibrated 14C ages of both the kohitsugire indicated timing close to the peak of Fujiwara no Norinaga's career as a calligraphist. Based on the associations between the dated texts and the 14C results, it is concluded that the Genji monogatari emaki and Ban-dainagon ekotoba paintings could have been created in the middle of 12th century.

In this study, molluscan shells housed at the University Museum, the University of Tokyo, provided a new set of region-specific correction values (ΔR) for the western Pacific, in particular for the central part of the main islands in the Japanese Archipelago and the southwest islands of Japan. The values of 40 total samples were calculated from 11 regions. North of the main islands and in the Ryukyu Islands, the mean ΔR values showed comparatively small values, 5–40 14C yr; in the central part of the main islands, these values were 60–90 14C yr.

Mollusk shells provide brief (<5 yr per shell) records of past marine conditions, including marine radiocarbon reservoir age (R) and upwelling. We report 21 14C ages and R calculations on small (∼2 mg) samples from 2 Mesodesma donacium (surf clam) shells. These shells were excavated from a semi-subterranean house floor stratum 14C dated to 7625 ± 35 BP at site QJ-280, Quebrada Jaguay, southern Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 ± 60 to 730 ± 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty.

We compared 2 archaeological relics of different preservation environments, white substances adhering to a vessel from the Matsusaki site and to earthenware from Hirohata, by measuring their environmental radioactivity, 14C, 228Ra/226Ra, 234U/238U, and 87Sr/86Sr, and major element contents (Ca, Sr, Mg, Fe, and Mn). The results showed that the 2 materials were somewhat different and also reflected differences in their preservation environments. The chemical elements that were more abundant in the Matsusaki sample than in the Hirohata sample, Fe, Mn, 238U, and 232Th (parent of 228Ra), are also abundant in seaweed or seagrass. Contamination by 14C derived from rainwater after atmospheric nuclear tests was clearly observed in the white substance from Hirohata.

The traditional archaeological chronology in the Japanese Islands during the Jomon period was essentially based on the relative age given to cord-impressed patterns marked on pottery, as well as the shape of the pottery and the thickness of the cultural layers that were excavated. We aimed to correlate the classical archaeological chronology with calibrated radiocarbon dates, to posit a new chronology for the Jomon period in northeastern Japan. We calibrated 80 accelerator mass spectrometry (AMS) 14C dates from NE Japan and reconstructed a chronological timetable for Hokkaido and the Tohoku District. We collected 43 samples from 5 shellmounds and 2 archaeological sites on Hokkaido Island and 4 shellmounds in the Tohoku District in order to determine the calibrated age of their sites. ΔR values used on Hokkaido Island and the Tohoku District were between 282 and –158 yr and between ±0 and –40 yr, respectively. The large ΔR value for the eastern part of Hokkaido Island indicates the influence of the Oyashio Current, while an anomalous ΔR value was obtained from northern Hokkaido Island. These figures show larger apparent ΔR values than those from southwest Japan (Nakamura et al. 2007). The calibrated Jomon period in the investigated area was from 2000 to 200 yr younger than the previous chronology. Calibrated 14C ages of the shellmounds investigated ranged between ∼6000 and 3000 yr, correlating to the Early Jomon and Final Jomon periods as indicated by the former archaeological chronology of Honshu Island.

We report compound-specific radiocarbon analyses of organic matter in ocean sediments from the northeast Pacific Ocean. Chemical extractions and a preparative capillary gas chromatograph (PCGC) were used to isolate phospholipid fatty acids (PLFA) and n-alkanes from 3 cores collected off the coast of California, USA. Mass of samples for accelerator mass spectrometry (AMS) 14C analysis ranged from 13–100 μg C. PLFA extracted from anaerobic sediments in the Santa Barbara Basin (595 m depth) had modern Δ14C values (–20 to +54‰), indicating bacterial utilization of surface-produced, post-bomb organic matter. Lower Δ14C values were obtained for n-alkanes and PLFA from coast (92 m depth) and continental slope (1866 m) sediments, which reflect sources of old organic matter and bioturbation. We present a brief analysis of the blank carbon introduced to samples during chemical processing and PCGC isolation.

The Obi-Rakhmat Grotto is one of the key Paleolithic sites in Central Asia. Archaeological excavations have revealed 22 strata containing archaeological materials. Lithic assemblages from all cultural layers display features similar to both late Middle Paleolithic blade industries and early Upper Paleolithic complexes in Southwest Asia and the Siberian Altai Mountains; this suggests a gradual Middle-to-Upper Paleolithic transition occurred in western Central Asia. Hominid remains found at Obi-Rakhmat (layer 16) show a mixture of archaic and modern traits. Different chronometric methods (radiocarbon, optically stimulated luminescence [OSL], U-series, and electron spin resonance [ESR]) were applied to the site's deposits. It appears that 14C dates are more reliable in terms of correspondence to the general framework of the Paleolithic of Central Asia and neighboring regions, and after critical analysis and the deletion of outliers, the upper part of the site's cultural sequence can be dated between 36,000–41,400 BP (layer 7) and ∼48,800 BP (layer 14.1). The U-series dating results are less secure due to the high uranium content and the presence of detritus, which contaminates dated sediments (travertine). The OSL dating gave uniform ages for all cultural succession (∼8 m of deposits), and confirms a very rapid sedimentation rate. Results of ESR dating depend greatly on the choice of uptake model. Dates calculated for the early uptake to some extent correspond to 14C data. The linear uptake chosen by Skinner et al. (2007) makes sediments very old (about 55,000–90,000 yr ago), which contradicts 14C dates and does not correspond well to the regional archaeological context.

We present a time-saving modification to the ultraviolet (UV) oxidation method for analyzing dissolved organic carbon (DOC) concentration, Δ14C, and δ13C measurements in seawater and standard materials. A low background (∼0.2 ± 0.2 μM) was reported for pre-irradiated Milli-Q (MQ) water that was used to dilute samples for DOC 14C analysis (Beaupré et al. 2007). We use MQ water without pre-irradiation (background ∼0.9 ± 0.2 μM) to dilute the sample. This method is suitable for small-volume, high-concentration samples (mass of sample DOC overwhelms mass of MQ water DOC). An acceptable precision of Δ14C measurements (5–9‰) is maintained. This revised method reduces the preparation time for diluted DOC Δ14C samples from 2 days to 1 day.

A sample preparation workshop was convened at the 20th International Radiocarbon conference, with about 30–40 attendees. The term “sample preparation” was not further specified to allow participants to address the laboratory issues most important to them. Given the short time available, the focus quickly narrowed to details of graphite preparation for accelerator mass spectrometry (AMS), with particular interest in procedures for small samples, and hence we have changed the title to reflect the focus. Here, we summarize the workshop discussion, adding additional background information and references to publications. Several aspects of graphite preparation are included: catalyst types and ratio of catalyst to carbon; optimal reaction temperatures for various sample sizes; methods for water removal; types of pressure transducers; preconditioning of catalyst; and problems with blank values in very small samples. The pros and cons of sample dilution were also discussed.

Changes of the Aral Sea level have been observed in 3 sediment boreholes, 2 outcrops, and associated archaeological sites. The obtained results are supported by 25 radiocarbon dates. Major trends of lake-level changes have been reconstructed in some detail for the last 2000 yr, and additional data provide an outline of fluctuations throughout the Holocene. Several distinct changes are shown to precede the modern, human-induced regression of the Aral Sea. These include: 1) the latest maximum in the 16th–20th centuries AD (53 m asl); 2) a Medieval “Kerderi” minimum of the 12th–15th centuries AD (29 m asl); 3) the early Medieval maximum of the 4th–11th centuries AD (52 m asl); and 4) a near BC/AD low-stand, whose level is not well established. Since then, events are only inferred from sparse data. The studied cores contain several sandy layers representing the lowering of the lake level within the Holocene, including the buried shore-bar of ∼4500 cal BP (38 m asl), and shallow-water sediments of ∼5600 cal BP (44 m asl), 7200 cal BP (28 m asl), and 8000 cal BP (26.5 m asl).

Prehistoric cultures in Armenia are still poorly known; thus, accelerator mass spectrometry (AMS) radiocarbon dates are invaluable in constructing an accurate chronology. Bone samples have been collected from sites representing the Middle Paleolithic, Chalcolithic, and Early Bronze periods. Most of the bone samples are poorly preserved. We describe the separation technique for the extraction of both the bioapatite and collagen fractions. In many cases where the bone had very low organic material content, the collagen fractions yielded a younger age, although the ages of bioapatite fractions were found to be in good agreement with associated archaeological artifacts. In cases where bone was well preserved, both fractions exhibited ages in good agreement with the artifacts. The accuracy of 14C dating of bone material always depends on its degree of preservation, and each case should be carefully evaluated to determine which fraction is less contaminated in order to accurately date a burial event.