Radiocarbon (14C) generated by the thermonuclear tests in the late 1950s to early 1960s has been used as a tracer to study atmospheric and oceanic circulations, carbon exchange between different reservoirs, and fossil fuel emissions. Here we report the first measurements of 14C in atmospheric CO2 of maritime air collected over the South China Sea (SCS) during July 2014. We also present 14C of the dissolved inorganic carbon (DIC) in the sea surface water in the same region. Most of the Δ14C values of the atmospheric CO2 vary in the range of 15.6±1.6‰– 22.0±1.6‰, indicating that the central SCS maritime air is well-mixed and consistent with the clean background air in the Northern Hemisphere. The 14C values of the DIC (DI14C) in the surface seawater vary between 28.3±2.5‰ and 40.6±2.7‰, mainly due to the lateral mixing between the SCS and western Pacific. The average surface seawater DI14C is 15.4 ± 5.1‰ higher than that of the maritime air 14CO2. The reversal of the sea–air Δ14C gradient occurred at ∼2000, marking the start of the upper ocean transferring bomb 14C back to the atmosphere in the SCS.

Prince Rupert Harbour (PRH), on the north Pacific Coast of British Columbia, contains at least 157 shell middens, of which 66 are known villages, in an area of approximately 180 km2. These sites span the last 9500 yr and in some cases are immense, exceeding 20,000 m2 surface area and several meters in depth. Recent archaeological research in PRH has become increasingly reliant on radiocarbon dates from marine shell for developing chronologies. However, this is problematic as the local marine reservoir effect (MRE) remains poorly understood in the region. To account for the MRE and to better date the Harbour’s sites, we propose a ΔR of 273±38 for the PRH area, based on our work at the site of Kitandach (GbTo-34), a massive shell midden-village centrally located within the Harbour. We followed the multiple paired sample approach for samples from specific contexts and ensured contemporaneity within the groups of marine and terrestrial materials by statistically assessing for outliers using the χ2 test. Taking together, the results for this and previous studies, it appears the MRE was fairly constant over the past 5000 yr.

The Jomon culture is an ancient Japanese society that existed during approximately 14,000 to 400 BC and which is characterized by Jomon (cord pattern) pottery. To investigate the paleodiet of the people of northeastern Tohoku in Japan during the Final Jomon period (about 1000–400 BC), we studied three sites in Aomori Prefecture, the center of the Kamegaoka culture. The Fubinashi site is on the coast and was supported by a rich fishing culture. Imazu was a coastal salt-making site. Sugisawa is a mountainous inland site on the banks of a river. We determined the 14C ages of the interior and exterior surfaces of carbonized material on potsherds and compared the data with pottery typology and age to study the marine reservoir effect. We also analyzed the bulk carbon and nitrogen stable isotopes and C:N ratios to determine the presence of aquatic foodstuffs. The organic residues from pottery typology corresponding to the described analyses provided a general perspective of differences in the ancient diets at each site. When we recovered sufficient lipids, we analyzed compound-specific stable isotopes of fatty acids to obtain a multilateral view of those diets. Our findings indicate that the diets of inhabitants of both Fubinashi and Imazu consisted primarily of marine products and some terrestrial foodstuffs, whereas people from Sugisawa processed mainly C3 plants and some terrestrial animals and aquatic commodities.

We present a method for the extraction of dissolved organic carbon (DOC) from water. The method is adapted from Burr et al. (2001) using the basic steps: 1) sample filtration; 2) acidification to liberate and remove dissolved inorganic carbon (DIC); 3) evaporation of the sample to isolate salts that include trace quantities of carbon; 4) combustion of the salts; and 5) purification of the CO2. Two significant improvements have been made to the earlier method. The first is to use wet oxidation with potassium permanganate to oxidize organics in place of the combustion step and the second is the development of a reduction/oxidation purification procedure to remove sulfur and nitrogen oxides that may form during the oxidation step. Wet oxidation has a practical advantage over the previous method because it proceeds at low temperature (70 °C). The original method required quartz vessels to oxidize the salts at 900 °C. At this temperature, salts in the samples formed gases that interfered with the isolation of CO2 and the quartz vessels degraded with each combustion, affecting their structural integrity. The expensive quartz vessels could only be used for a limited number of samples, whereas Pyrex vessels used for wet oxidation are inexpensive and can be used indefinitely.

The blank fraction modern carbon (f) and its mass dependence for the refined technique was determined from repeat analyses of salicylic acid produced from petrochemicals. For samples with a mass m above 0.5 mg, F = 0.0083 ± 0.0011. For samples below 0.5 mg, the blank follows a 1/m dependence as observed for other accelerator mass spectrometry (AMS) 14C measurements (Donahue et al. 1990). The reproducibility of the method is demonstrated using repeat measurements from a variety of samples, including a sample measured with the former high-temperature 900 °C combustion technique. The virtues of the wet oxidation method are that it is economical, produces a low blank, and provides good reproducibility.

The area of Chroberz (southern Poland) poses questions of an interdisciplinary character comprising geomorphologic, sedimentation, and archaeological-historical problems. The main aim of this study was to identify the geomorphologic response to changes in the natural environment that took place in the area of the loess plateau (and its close vicinity) as a result of its settlement by man and of climate change. Periods of particularly intense human activity (land-use changes, deforestation, and agriculture) were recorded as changes in the type of sedimentation, i.e. organic sedimentation substituted for mineral one; it was extremely intensive during the Neolithic Age, Iron Age, and Early Middle Ages. The conducted fieldwork research, analysis of available archaeological materials, and radiocarbon dating results show that there is a direct connection between human economic activity in primeval and historic times and between soil erosion and accumulation of colluvial/alluvial fans in the surroundings of the locality of Chroberz. 14C dates documenting the age of colluvial sediment formation show that individual areas of the upland were settled by humans asynchronously. On the basis of a low facial variability, or, occasionally, even homogeneity, of individual colluvia (from soil erosion) and their considerable thickness, it can be concluded that the land was in constant use or that the intervals with no human activity were relatively short. The progressing human impact process is visible both in the form progradation recorded as the changes in 14C ages (e.g. from 1440 ± 100 to 780 ± 80 BP) and in textural (e.g. chemical) features of sediments of which the examined fans are composed.

Based on archaeological and radiometric constraints, previous studies have divided pre-Columbian times of Ecuador into a succession of cultural periods. The Paleoindian and Preceramic periods encompass the time from the first Amerindian occupation to about 4000 BC. The Formative period extends from ∼4000 to ∼300 BC, while the Regional Development (∼300 BC to ∼AD 700) and Integration periods predate the Columbian period, which starts in AD 1533 in Ecuador. The Formative cultural period is poorly known from earlier studies. Here, we bring the first documentation of Formative age occupation around Tungurahua Volcano, 120 km SW of Quito, and show that local settlements were devastated by a violent eruption around 1100 cal BC. Recent volcanological works combining lithostratigraphic, petrologic, and geochronologic analyses reveal that the steep-sloped Tungurahua edifice suffered a major Late Holocene flank failure. We show that the failure event resulted from a major explosive eruption triggered by massive magma intrusion inside the volcano. Decompression of the magma due to a flank collapse resulted in a violent, high-velocity directed blast explosion, which deposited charcoaland sherd-rich ash layers upon and near the volcano. Our 14C results range from 2225 ± 30 to 5195 ± 45 BP, but most cluster between 2640 ± 45 and 3195 ± 45 BP. A calibration analysis indicates that the event took place at ∼1100 cal BC, in the Formative period. We gathered 38 pottery sherds from 3 localities. The sherds show a diversity of size, shape, color, and ornamentation. Examination of pastes, surface finish, and firing indicates that our material shares many common features from site to site. The material from Tungurahua shares affinities with the Cotocollao tradition, which developed in the Quito region between 1500 and 500 BC, and with the Machalilla tradition (coastal region of Ecuador), with the occurrence of carinated bowls with punctuate decorations at 1500–1000 BC. Our study reveals that the ∼1100 cal BC Plinian eruption of Tungurahua Volcano is among the oldest known volcanic disasters in the Andes.

Two principal reasons for the inherent uncertainty in 14C dating of calcareous sediments such as tufa or those of lacustrine origin are the unknown initial 14C activity (Ao) of the sediment, mainly affecting younger (Holocene) samples, and contamination of older sediments with recent carbonate, causing 14C ages to be excessively young. To assess the contamination effect, samples of old tufa from the Riss/Würm interglacial were examined. These sediments contain essentially no 14C except that contributed by surface contamination. Tufa samples were crushed and grains ranging in size from <1 mm, 1 to 2mm, up to 4 to 5mm were separated for analysis; 2M HCl was then used to dissolve the samples in successive steps. 14C measurements indicated that each subsequent soluble fraction obtained from porous tufa gave a successively older age, indicating that the surface of the sample was contaminated by younger carbonates. No consistent effect of grain size on the 14C age was observed. Compact tufa proved to be less subject to contamination. 14C ages obtained on this material were also too young, yet older than the age obtained from porous tufa samples.

14C ages of interglacial tufa were cross-checked with the 230Th/234U dating method, using samples of very clean calcite which overlies the tufa blocks. Inferred 230Th/234U ages of the interglacial tufa (which had yielded 14C dates ranging from 25,000 to 37,000 yr) coincided with the last interglacial (Riss/Würm, Stage 5). Samples of Holocene tufa, in which contributions of recent 14C from surface contamination would pose less of a problem, yielded 14C and 230Th/234U dates which were in excellent agreement.

Time series of annual Δ14C and δ13C in tree rings of Sequoiadendron giganteum, AD 998–1510, are similar in form. The Δ14C series completes, with data of Stuiver and Braziunas (1993), a 957-yr time-series. Discrete Fourier transformation of detrended Δ14C reveals periods of 126, 91, 56, 17.6, 13.6, 10.4, and 7.1 yr. Non-random differences exist between decadal averages of the Sequoiadendron Δ14C data and data of Stuiver and Becker (1993). Periods of 7–17 yr may correspond to Schwabe or related climatic cycles; these have 10–17-yr periods and amplitudes < 6‰ (AD 1100–1250), and periods near 7 yr with amplitudes up to 10‰ (AD 1380–1420). Abrupt increases in Δ14C are mainly less than 5‰, and do not constitute convincing evidence of increased 14C production from supernovae or solar proton events. The δ13C time-series is likely to reflect climate change, and for centennial periodicity lags behind Δ14C by 20–40 yr (centennial time-scale) and 25–50 yr (millennial). Phase-shifts between solar luminosity and surface Δ14C are 125–175 yr and 20 yr for millennial and centennial cycles, respectively. The study suggests that strongest climate effects may therefore follow peak luminosity by 125–175 yr for millennial cycles and 20–40 yr for centennial cycles.

An age-depth model based on radiocarbon dates was produced from a Holocene profile collected from a rich fen situated in the Beskid Sądecki Mountains (the Outer Western Carpathians, southern Poland). The model is compared against the results of palynological and loss on ignition (LOI) analyses supplemented by the identification of organic deposits. Five distinct palynological episodes are detected. These potential palynological age markers are critically compared with the results of age-depth modeling and other dated profiles. The results presented distinctly show that using palynological episodes as age markers for age-depth construction may be highly misleading.

In conformance with the request of the editors, ages in this date list have been calculated with the Libby half life value, 5568 ± 30 yr. We should like to mention, however, that the “effective” and, possibly, the true value may differ from this by several hundred years (see discussion by Kohler and Ralph, 1961). The measurements of samples of known age indicate that the “effective” half life value is close to 5800 yr, except for specific recent periods.

We present 37 new radiocarbon (14C) measurements from mollusk shells fragments sampled along the Chilean continental margin and stored in museum collections with known calendar age. These measurements were used to estimate the modern pre-bomb regional marine 14C age deviations from the global ocean reservoir (∆R). Together with previously published data, we calculated regional mean ∆R values for five oceanographic macro regions along the coast plus one for a mid-latitude open ocean setting. In general, upwelling regions north of 42ºS show consistent although sometimes highly variable ∆R values with regional averages ranging from 141 to 196 14C yr, whereas the mid-latitude open ocean location of the Juan Fernández archipelago and the southern Patagonian region show minor, ∆R of 40±38 14C yr, and 52±47 14C yr respectively. We attribute the alongshore decreasing pattern toward higher latitudes to the main oceanographic features along the Chilean coast such as perennial coastal upwelling in northern zone, seasonally variable upwelling at the central part and the large freshwater influence upon the southern Patagonian channels.

We obtained over 200 archaeological wood specimens from the southeastern part of the Altai Mountains (Russia) to establish accurate calendar dates of the timbers using both radiocarbon and tree-ring analyses. Most timbers came from small and elite tombs of the Pazyryk culture (Siberian Scythians of the Iron Age period). Timbers from Hun-Sarmatian and Turk times (1st millennium AD) were studied for the first time. Three floating tree-ring width chronologies of larch (Larix sibirica) with lengths of 486 yr to 144 yr were developed from the tree-ring data. Tree rings of the composite 486-yr chronology of the Pazyryk culture represent the regional scale of Altai tree-ring width variability between about 720–240 BC. The composite chronology dates the earliest construction of Pazyryk culture tombs to ∼320 BC (ordinary tombs) and the latest ones at 240 BC (Pazyryk noble tomb #5). The composite chronology might be used for tree-ring dating wood from Scythian tombs in the region. It will also help confirm the precision of 14C dating of the Scythian tombs around the Hallstatt plateau of 14C calibration curves. We developed a 110-yr decadal 14C sequence from the Kurayka site that dates Kok-Pash culture timbers back to cal AD 240 (Hun-Sarmatian period). 14C dates of wooden poles from 3 sites of Turk stone enclosures suggested wood cutting dates between cal AD 470 and 830. The results demonstrate that crossdating tree rings along with 14C dating of crossdated rings provide the most reliable and highest precision dates for these archaeological sites.

The measurements presented in this list are part of the joint research program “Sonderforschungsbereich 95” of Kiel University for interdisciplinary research on problems of “Interaction Sea-Sea Bottom”, sponsored by the Deutsche Forschungsgemeinschaft. They are directed 1) to the study of the path of 14C from the atmosphere into argillaceous sediments, and 2) to date stratigraphic records within sediment. Associated problems are to identify sources of different 14C activity that contribute to recent deposits, and to learn about effects of morphologic and hydrographic factors, especially of bottom currents, on sedimentation sequence. Even short term processes can be successfully studied by analyses of bomb produced radiocarbon in the marine environment.

This article is a reply to the preceding rejoinder by Fantalkin et al., which they wrote in response to our article concerning radiocarbon dates of Iron Age sites in the Mediterranean region measured at Groningen (van der Plicht et al. 2009). We do not agree with much of their criticism. Our reply is presented in detail with new viewpoints and evaluations concerning a number of sites in the Levant, including Tel Dan, Megiddo Stratum VIA (= K/4), Horvat Haluqim, Tell el-Qudeirat, Khirbet en-Nahas, Tel Rehov, as well as sites in the central and western Mediterranean region, particularly Carthage and Huelva. Our main conclusions are that 14C dating supports an Iron Age High Chronology for the above sites, though more 14C dating is required, particularly in Greece and the central and western Mediterranean region, to substantiate and refine the current state of knowledge. We prefer detailed investigations per individual site, evaluating both 14C dates and site stratigraphy, rather than the wholesale averaging of strata over many sites, which may lead to oversimplification and erroneous results, also on stratigraphic grounds. Contrary to Fantalkin et al. (2011), we emphasize the importance of 14C dating as an independent methodology—chronostratigraphy—to evaluate site stratigraphy. The 14C dates of Megiddo Stratum VIA (=K/4) clearly indicate field-stratigraphic problems at this site.

This article presents a case study of Lower Lough Erne, a humic, alkaline lake in northwest Ireland, and uses the radiocarbon method to determine the source and age of carbon to establish whether terrestrial carbon is utilized by heterotrophic organisms or buried in sediment. Stepped combustion was used to estimate the degree of the burial of terrestrial carbon in surface sediment. Δ14C, δ13C, and δ15N values were measured for phytoplankton, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and particulate organic carbon (POC). Δ14C values were used to indicate the presence of different sources of carbon, including bedrock-derived inorganic carbon, “modern,” “recent,” “subsurface,” and “subfossil” terrestrial carbon in the lake. The use of 14C in conjunction with novel methods (e.g. stepped combustion) allows the determination of the pathway of terrestrial carbon in the system, which has implications for regional and global carbon cycling.

The La Jolla Radiocarbon Laboratory has measured carbon-14 concentrations in seawater samples collected from 1957 through 1972. The dissolved inorganic carbon in seawater was extracted on board research vessels and was returned to the laboratory for processing and measurement. Both surface and sub-surface samples were collected, primarily from the Pacific Ocean, but also from the Indian Ocean. The purpose of the seawater measurements was to determine the distribution of bomb-produced radiocarbon in the surface water of the Pacific and Indian Oceans, the sub-surface penetration of bomb 14C, the change in 14C/12C ratios with depth, and thus the rate of uptake of bomb 14C by the oceans. This project was the basis of the author's doctoral dissertation (Linick, 1975).

The first results of radiocarbon dating of the ancient sites in the Russian Far East were published early in the 1960s (Okladnikov 1964). We now have enough data to establish the main features in the 14C chronology of the Stone and Bronze Age cultures in Primorye, one of the archaeologically well-studied regions of the Russian Far East.

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.

Reliable radiocarbon dating depends upon well-defined samples. We have been investigating whether or not reliable 14C dates can be obtained directly from sub-fossil insect cuticle or biochemical fractions derived from it. Initial carbon and nitrogen stable isotope measurements on sub-fossil insect chitin from species with known feeding behaviors found within a single site (St Bees, Cumbria) clustered in a manner reminiscent of trophic level effects seen in terrestrial ecosystems. Although this finding implied some chemical stability, the measurement of CN ratios from the same samples indicated compositional variability. In addition, 14C dates obtained from these same samples were different from dates obtained from plant macrofossils found at the same depth. We have experimented with protocols designed to biochemically reduce chitin to its principle carbohydrate component glucosamine with the aim of using this compound to generate reliable 14C dates. Solvent extractions of sub-fossil chitin were carried out to remove both endogenous and exogenous lipid-soluble materials. Base hydrolysis reactions designed to extract polypeptides retained surprisingly high levels of contaminating amino acids. Proteinase K enzyme treatment had little affect on the level of amino acid contamination. Strong acid hydrolysis reactions designed to depolymerize chitin to glucosamine yielded only 5% glucosamine. Clearly alternative methods of chitin depolymerization must be identified before the purification and 14C dating of glucosamine from sub-fossil chitin becomes practical.

This list contains results obtained between 1981 and 1985. Since the first description of the laboratory (Carmi, Noter & Schlesinger, 1971) the following changes were made. Two proportional counters are now used: 1) 0.5L volume, 0.865 ± 0.023 cpm background, 12.830 ± .134 cpm NBS oxalic acid standard (old); 2) 0.25L volume, 0.484 ± 0.023 cpm background, 6.185 ± .123 cpm NBS oxalic acid standard (old). The passive shield has been increased by 2cm of mercury next to the counters. For anticoincidence, a modular, hand-made gas counter is used. The laboratory was transferred to the ground floor of a 7-storey building. Data acquisition and processing are done with a sealer/buffer built at the institute and an IBM PC computer. Samples are filled into the counters and counted for ca 1000min at least twice. The sample preparation method and counter filling pressure have not been changed.