This study applied, radiocarbon dating to charcoal and mollusk samples from Sernambetiba and Amourins archaeological sites in the Northeast region of Guanabara Bay, in the state of Rio de Janeiro, Brazil, to assess the marine radiocarbon reservoir effect (MRE) of this area, being applied for the correction of the marine samples ages. The results for this estuarine system were ΔR = –87 ± 90 14C yr and ΔR = –244 ± 70 14C yr for 3970 ± 70 14C yr BP and 2357 ± 60 14C yr BP, respectively. Based on these findings, calibrated 14C ages were calculated for Sernambetiba and Amourins shell mound sites surrounding the bay. Marine samples from the Guapi site were analyzed and only their radiocarbon ages presented because there were no paired terrestrial samples for the MRE assessment. These results are coherent with previously published values also derived from archaeological samples for the Rio de Janeiro state coastal region and contribute to the interpretation of human occupation of the region during the Holocene.

We present new data on regional correction factor (ΔR) conducted for Chukotka, the Commander Islands, and the western Aleutian Islands and summarize data previously published for the other parts of the region. Paired radiocarbon dates of coeval marine and terrestrial materials from the archaeological site Kaniskak were obtained in Chukotka, and one such pair was analyzed from Shemya Island (western Aleutians). Three samples of sea otter (Enhydra lutris) bones of known collection date were used for the Commander Islands. In conjunction with previously published data, the new results showed that ΔR estimates conducted for the five regions of the northern Pacific do not differ statistically. ΔR assessments combined for archaeological sites resulted in probability density curves of the same shape as that of marine organisms. Comparison of ΔR estimates made with various species of marine animals showed that sea otters and small fishes residing within coastal waters throughout their life histories are better suited for ΔR measurements than migrating seals, on the one hand, and the shells of sedentary organisms, on the other. The study provides additional support to the hypothesis that the northern Pacific is characterized by the same reservoir offset, which we estimate as 525 ± 75 yr.

Direct dates of pottery obtained from food crusts or other organic residues on the vessel surfaces can be affected by a reservoir effect and/or an old wood effect and therefore be unreliable. Hence, there is a need for alternative ways to directly date pottery. Moss is used as temper by several cultural groups of the late 6th to early 4th millennium cal BC in northwestern Europe. After the pottery is fired, charred moss remains are often preserved in the clay, so that relatively short-lived plant material with a direct chronological link to the pottery and human occupation is available for radiocarbon (14C) dating. In this study, charred moss temper is extracted for accelerator mass spectrometry (AMS) 14C dating from pottery of the Swifterbant Culture and Spiere group in the Scheldt river valley (Belgium). The moss dates are then compared to reference dates of organic macro-remains from the same sites and food crust dates with or without a reservoir effect of the same pottery. Eleven out of 13 moss dates are in line with the expected pottery age. The paired dates of moss temper and food crusts from the same potsherds confirm a freshwater reservoir effect (FRE) for the latter. We conclude that moss temper has great potential as a sample material for direct pottery dating. However, more research on the extraction and pretreatment of moss temper as well as on the reliability of moss dates is necessary in the future.

Un trabajo de rescate arqueológico en la cuenca alta del Río Loa (norte de Chile) resultó en el hallazgo de una inhumación prehispánica de un infante asociado a variados atavíos y ofrendas, junto a los restos óseos parciales de una adolescente. Ambos individuos fueron sometidos a análisis de isótopos estables para establecer paleodieta (δ13C y δ15N) y movilidad (δ18O y 87Sr/86Sr). Además, se efectuaron dataciones radiocarbónicas pareadas de los restos bioantropológicos y culturales con el fin establecer la cronología de la inhumación y, a la vez, evaluar la existencia de un posible efecto reservorio marino. Los resultados isotópicos sugieren consumo de dieta principalmente terrestre y un origen local para los individuos, aunque con una ingesta moderada de recursos marinos. Los fechados radiocarbónicos presentan una inesperada diferencia entre las edades de las ofrendas y los restos humanos, indicando la existencia de un importante efecto reservorio. Dichos resultados dan nuevas luces sobre el consumo de alimentos marinos durante el Formativo temprano en la región, a la vez que permiten ejemplificar los alcances de efectuar dataciones pareadas de restos humanos y culturales.

The elk/moose (Alces alces) was an important resource for prehistoric societies. In prehistoric art, it is often depicted in connection with water. Biologists find that elk spend much time in water and consume considerable amounts of aquatic plants. As freshwater plants can have reservoir ages of hundreds or even thousands of years, there is a risk of a significant reservoir effect in elk bones and antler, and artifacts made of these materials. This pilot study followed several approaches to investigate the possibility of a freshwater reservoir effect in elk. I analyzed modern, historical and archaeological bones and antler from several sites across Eurasia. Skull bone and antler of the same individual were radiocarbon dated, as antler is formed in summer, when the proportion of aquatic diet is supposed to be highest. Age offsets measured in this study were zero to about 500 years. A difference between bone and antler could not be determined. The reservoir effect appears to be smaller than estimated from accounts of elk diet, even in regions where a substantial freshwater reservoir effect is expected. Therefore, the hypothesis of a large proportion of aquatic diet can be rejected for several of the individuals studied here.

Coastal lake sediments are valuable paleoclimate archives provided that they can be accurately dated. Here, we report radiocarbon ages of bulk sediment organic matter (OM), plants, shells, particulate OM, and dissolved OM from coastal lakes in Florida. Bulk sediment OM yielded ages that are consistently older than contemporaneous plants and shells, indicating significant radiocarbon deficiencies in sedimentary OM in these lakes. The data show that the OM radiocarbon deficiency varies over time and with location, making it impossible to determine a proper correction factor for radiocarbon ages of bulk sediments from these lakes. As a result, we consider ages obtained from bulk sediment OM from these lakes unreliable. The age reversals in bulk sediment OM observed in the sediment cores are likely caused by rapid increases in erosion and sedimentation resulting from large storm events. The data also show that sedimentation rate can vary considerably within a given lake, implying that an age-depth model established for one core cannot be directly applied to other cores despite their close proximity. Analyses of shells from one of the lakes suggest that fresh/brackish-water shells may serve as a good substrate for radiocarbon dating owing to a small reservoir effect on inorganic carbon.

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.

Inland water bodies contain significant amounts of carbon in the form of dissolved inorganic carbon (DIC) derived from a mixture of modern atmospheric and pre-aged sources, which needs to be considered in radiocarbon-based dating and natural isotope tracer studies. While reservoir effects in hardwater lakes are generally considered to be constant through time, a comparison of recent and historical DI14C data from 2013 and 1969 for Lake Constance reveals that this is not a valid assumption. We hypothesize that changes in atmospheric carbon contributions to lake water DIC have taken place due to anthropogenically forced eutrophication in the 20th century. A return to more oligotrophic conditions in the lake led to reoxygenation and enhanced terrigenous organic matter remineralization, contributing to lake water DIC. Such comparisons using DI14C measurements from different points in time enable nonlinear changes in lake water DIC source and signature to be disentangled from concurrent anthropogenically induced changes in atmospheric 14C. In the future, coeval changes in lake dynamics due to climate change are expected to further perturb these balances. Depending on the scenario, Lake Constance DI14C is projected to decrease from the 2013 measured value of 0.856 Fm to 0.54–0.62 Fm by the end of the century.

We report new accelerator mass spectrometry radiocarbon (AMS 14C) dates of bones from humans, animals, and fish from grave 12 of the Lebyazhinka V Eneolithic burial ground in the middle Volga River region, Russia. Earlier conventional dates established a chronology. This has to be adjusted by new insights: the date has to be corrected for reservoir effects. For this purpose we redated bone from a human, and for herbivore and freshwater fauna from the same context, and included measurements of the stable isotopes δ13C and δ15N. The reservoir offset for the human appears to be about 700 14C yr.

Terrestrial plant remains in the sediments of lakes from semi-arid and arid regions are rare and therefore the establishment of a sediment chronology depends on accurate assessment of the reservoir effect of the lake water. In a study of Genggahai Lake in the Gonghe Basin, northeastern Qinghai-Tibetan Plateau, we used accelerator mass spectrometry radiocarbon (AMS 14C) dating to determine the age of (1) dissolved inorganic carbon in the water (DICLW), (2) macrophyte remains in the uppermost samples of core sediments, (3) living P. pectinatus in the lake, and (4) dissolved inorganic carbon of spring water in the catchment. The results show that the ages of the DICLW (910 14C yr BP on average) were much younger than the ages of the groundwater (6330 14C yr BP on average), which may result mainly from CO2 exchange between the lake water and the atmosphere. In addition, the 14C ages of DICLW and macrophyte remains in the uppermost core sediments varied from site to site within the lake, which we ascribe to the different photosynthesis rates of Chara spp. and vascular plants. The higher photosynthesis rate of Chara spp. decreases lake-water pCO2, which leads to more atmospheric CO2 being absorbed by the lake water, and thereby greatly reducing the age of carbon species in areas dominated by Chara spp. Although Genggahai Lake is well mixed, the differences between the apparent ages of the lake water are significantly modulated by the photosynthesis intensity of submerged plants.

To measure chronological changes in the marine reservoir effect in western Japan, 47 marine shells and 35 terrestrial plants from the same horizons in two cores of Holocene sediments were radiocarbon dated by the KIGAM AMS facility. These cores were obtained from the central and northern parts of Hakata Bay using a Geoslicer device. This drilling tool provided us continuous coverage and many samples. In order to determine the species effects on the marine reservoir effect, both filter feeders and a deposit feeder were selected for study. Based on the analysis of lithology, mollusk assemblage, and 14C dating, two sedimentary units were determined: the upper bay floor sediment and lower estuarine sediment. Reservoir ages of 280±150 yr (n=17) and 340±140 yr (n=18) were obtained from the central and northern parts of Hakata Bay during 2000 to 10,000 cal BP, respectively. Based on these results, it is clear that a paleoenvironmental change occurred here as a result of sea-level rise during the deglacial period.

Fruit carbonate of Buglossoides arvensis (syn. Lithospermum arvense) is a valuable dating and paleoenvironmental proxy for late Quaternary deposits and cultural layers because CaCO3 in fruit is assumed to be accumulated from photosynthetic carbon (C). However, considering the uptake of HCO3– by roots from soil solution, the estimated age could be too old depending on the source of HCO3– allocated in fruit carbonate. Until now, no studies have assessed the contributions of photosynthetic and soil C to the fruit carbonate. To evaluate this, the allocation of photo-assimilated carbon and root uptake of HCO3– was examined by radiocarbon (14C) labeling and tracing. B. arvensis was grown in carbonate-free and carbonate-containing soils (sand and loess, respectively), where 14C was provided as (1) 14CO2 in the atmosphere (5 times shoot pulse labeling), or (2) Na214CO3 in soil solution (root-labeling; 5 times by injecting labeled solution into the soil) during one month of fruit development. Distinctly different patterns of 14C distribution in plant organs after root- and shoot labeling showed the ability of B. arvensis to take up HCO3– from soil solution. The highest 14C activity from root labeling was recovered in roots, followed by shoots, fruit organics, and fruit carbonate. In contrast, 14C activity after shoot labeling was the highest in shoots, followed by fruit organics, roots and fruit carbonate. Total photo-assimilated C incorporated via shoot labeling in loess-grown plants was 1.51 mg lower than in sand, reflecting the presence of dissolved carbonate (i.e. CaCO3) in loess. Loess carbonate dissolution and root-respired CO2 in soil solution are both sources of HCO3– for root uptake. Considering this dilution effect by carbonates, the total incorporated HCO3– comprised 0.15% of C in fruit carbonate after 10 hr of shoot labeling. However, if the incorporated HCO3– during 10 hr of shoot labeling is extrapolated for the whole month of fruit development (i.e. 420-hr photoperiod), fruit carbonate in loess-grown plants incorporated approximately 6.3% more HCO3– than in sand. Therefore, fruit carbonates from plants grown on calcareous soils may yield overestimated 14C ages around 500 yr because of a few percentage uptake of HCO3– by roots. However, the age overestimation because of HCO3– uptake becomes insignificant in fruits older than approximately 11,000 yr due to increasing uncertainties in age determination.

This article presents new values for the Scottish marine radiocarbon reservoir effect (MRE) during the Mesolithic at 4540–4240 BC (6490–6190 BP) and the Medieval period at AD 1460–1630 (490–320 BP). The results give a ΔR of –126±39 14C yr for the Mesolithic and of –130±36 14C yr for the Medieval. We recalculate previously published MRE values for the earlier Holocene in this region, at 6480–6290 BC (8430–8180 BP). Here, MRE values are slightly elevated, with a ΔR of 64±41 14C yr, possibly relating to the 8.2ka BP cold event. New values for the Mesolithic and Medieval indicate lower MRE values, broadly consistent with an existing data set of 37 mid- to late Holocene assessments for Scottish waters, indicating stable ocean conditions. We compare the intercept and probability density function (PDF) methods for assessing ΔR. The ΔR values are indistinguishable, but confidence intervals are slightly larger with the PDF method. We therefore apply this more conservative method to calculate ΔR. The MRE values presented fill important gaps in understanding Scottish marine 14C dynamics, providing confidence when calibrating material from critical periods in Scotland’s prehistory, particularly the Mesolithic, when the use of marine resources by coastal populations was high.

We recently started a systematic approach to determine the reservoir age in southeast Arabia and its dependence on mollusk species and their environment. This part of the study concentrates on local reservoir age and stable isotopes of the lagoonal species Terebralia palustris and Anadara uropigimelana at Khor Kalba, Oman Sea. Environmental and nutritive influences on mollusks are reflected in the radiocarbon and stable isotope signal. We found a local reservoir age of A. uropigimelana of about 940 yr and that of T. palustris as 800 yr. Sclerochronological analyses yielded information about seasonality of growth and death in A. uropigimelana. The modern shell of Periglypta reticulata shares food resources and habitat with Anadara sp., of which we did not find a modern specimen. It provided information on response to changes in temperature in the lagoonal system needed for suitability as reflecting climatic conditions. We were interested in carbon pathways of the mangrove in Kalba and a mangrove planted anew on a former mangrove sediment in Ajman. Being an obvious source of charcoal and food of T. palustris makes this information necessary. Further analyses will be performed to interpret changes in reservoir age in complex lagoonal systems as reaction to environmental variability.

Reservoir age offsets are widely used to correct marine and speleothem radiocarbon age measurements for various calibration purposes. They also serve as a powerful tracer for carbon cycle dynamics. However, a clear terminology regarding reservoir age offsets is lacking, sometimes leading to miscalculations. This note seeks to provide consistent conventions for reporting reservoir 14C disequilibria useful to a broad range of environmental sciences. This contribution introduces the F14R and δ14R metrics to express the relative 14C disequilibrium between two contemporaneous reservoirs and the R metric as the associated reservoir age offset.

It is widely recognized that when marine resources form a significant proportion of the human diet, this results in radiocarbon ages for human remains that are significantly older than the contemporary atmosphere. While there has been widespread assessment of marine 14C reservoir ages, there has been little study of the freshwater equivalent. However, recent analyses of human bone from archaeological sites in the Danube Valley have confirmed the existence of a large freshwater 14C reservoir effect.