Radiocarbon Values Research Articles

Validation and otolith-mass prediction of age and growth for cardinal snapper Pristipomoides macrophthalmus of the Caribbean Sea

Abstract Cardinal snapper Pristipomoides macrophthalmus is a commercially important, but commonly misidentified, deepwater species in artisanal and semi-industrial fisheries throughout the Caribbean Sea. As with many tropical deepwater fishes, little is known about the biology or ecology of the species. Bomb radiocarbon (14C) dating was applied to cardinal snapper sagittal otoliths collected from the waters of Belize and Honduras during 2015–2019 to investigate the lifespan of the species from thin-sectioned otoliths with an evaluation of otolith mass as a proxy for age. Ages estimated from 28 thin-sectioned otoliths ranged from 7 to 68 years for fish that covered the range lengths and otolith masses available. Radiocarbon values were measured for each cardinal snapper otolith core, and two fish (one each from Belize and Honduras) had 14C signatures consistent with pre-bomb values, effectively validating a lifespan of at least 60 years. A curvilinear relationship between otolith mass and estimated age was robust (r 2 = 0.95) and is likely to produce age estimates with similar margins of error to traditional, more labor-intensive methods, such as counting increments from thin-sectioned otoliths. The otolith mass-to-age relationship is a well-supported method that provides a simple, low-cost approach that can be used by fishers, managers, and other stakeholders to assess the age composition of the cardinal snapper stock in the western Caribbean Sea for present and long-term monitoring.

Mineral surface area of sinking particles in the deep ocean interior: Preliminary implications

AbstractMeasurement of the mineral surface area (MSA) of sedimentary particles is a traditional approach for studying the transport and protection of organic carbon (OC) in marine systems. We investigated the application of MSA on the biological carbon pump in the deep ocean interior in the Ulleung Basin (UB), East/Japan Sea. This is the second study of sinking particle MSA, and the first in an ocean with no major riverine (terrestrial) input. We measured seasonal and vertical variations in the MSA of sinking particles and adjacent surface sediments in the UB. Mineral surface area values exhibit seasonal variations associated with particle composition, with a negative correlation with OC content and a strong positive correlation with the content of lithogenic material and the radiocarbon values of sinking OC. Our results indicate that the MSA of sinking particles may provide clues to the processes of particle resuspension and decomposition.

A radiocarbon bomb pulse model for estimating the age of North Atlantic cetaceans.

The tusk of the male narwhal is a prolonged canine tooth, reaching a size of up to 3 m in length. The tusk erupts through the young narwhal's upper left lip and, over time, develops into an elongated structure composed of dentine growth layers with an outer coating of cementum. In this study, we utilized bomb radiocarbon (14C) to estimate the ages of three narwhal tusks, which allowed us to validate the assumption that one growth layer is deposited annually in narwhal tusks. We used radiocarbon values from samples collected from the annual growth layers along the lengths of the erupted tusks and from the tip and base of embedded teeth, together with published radiocarbon data from three North Atlantic whale species, for the purpose of building a model of the incorporation of bomb radiocarbon in marine mammal tissues. The results obtained contribute significantly to our understanding of narwhal growth and longevity, enhancing our comprehension of isotope flow in the Arctic marine environment and their incorporation into the living tissue of a marine top predator. The bomb radiocarbon model can serve as a valuable reference chronology for dating museum or field specimens of narwhals and other North Atlantic marine animals.

Mesolithic Burials of the Volga-Urals

For the Mesolithic era, experts have identified two zones of ritualism: the northern with an elongated posture of skeleton and the southern with a crouched posture. Until recently on the territory of the Volga-Urals, Mesolithic burials were almost unknown. Therefore, the purpose of the article is to analyze the complexes for their attribution to the Middle Stone Age. The paper relevance is due to the low degree of the Mesolithic burials study in the territory under consideration. Methods and materials. The objects of the study were the materials of the monuments Mayak I, Syezhe I, Chekalino IV and Davlekanovo. In order to achieve the goal, the archaeological context of each monument was analyzed. To identify several objects of study, planigraphic and stratigraphic methods were used. The typological analysis was applied when structuring the funeral rite and the inventory. Lack of inventory in some burials made cultural and chronological attribution difficult. The radiocarbon method was aimed at establishing the chronological framework of the burials. Anthropological analyses were aimed at identifying morphological characteristics of the buried. Outcomes. Based on the results of the study, two traditions of the burial rite were revealed. The Mayak I and Syezhee I monuments depict the pose of the buried stretched out on their backs, while the Chekalino IV and Davlekanovo monuments show a crouched position on the right side. Radiocarbon values record the chronological differences between these groups. Anthropological characteristics are included in a wide range of variants of the proto-Uraloid or the Old Ural type. These differences can be explained both by the territorial peculiarity of the Volga-Ural region and by the fact that the monuments belong to different periods of the Mesolithic.

Rainfall Impacts Dissolved Organic Matter and Cation Export From Permafrost Catchments and a Glacial River During Late Summer in Northeast Greenland

ABSTRACTOngoing and amplified climate change in the Arctic is leading to glacier retreat and to the exposure of an ever‐larger portion of non‐glaciated permafrost‐dominated landscapes. Warming will also cause more precipitation to fall as rain, further enhancing the thaw of previously frozen ground. Yet, the impact of those perturbations on the geochemistry of Arctic rivers remains a subject of debate. Here, we determined the geochemical composition of waters from various contrasting non‐glacial permafrost catchments and investigated their impact on a glacially dominated river, the Zackenberg River (Northeast Greenland), during late summer (August 2019). We also studied the effect of rainfall on the geochemistry of the Zackenberg River, its non‐glacial tributaries, and a nearby independent non‐glacial headwater stream Grænse. We analyzed water properties, quantified and characterized dissolved organic matter (DOM) using absorbance and fluorescence spectroscopy and radiocarbon isotopes, and set this alongside analyses of the major cations (Ca, Mg, Na, and K), dissolved silicon (Si), and germanium/silicon ratios (Ge/Si). The glacier‐fed Zackenberg River contained low concentrations of major cations, dissolved Si and dissolved organic carbon (DOC), and a Ge/Si ratio typical of bulk rock. Glacial DOM was enriched in protein‐like fluorescent DOM and displayed relatively depleted radiocarbon values (i.e., old DOM). Non‐glacial streams (i.e., tributaries and Grænse) had higher concentrations of major cations and DOC and DOM enriched in aromatic compounds. They showed a wide range of values for radiocarbon, Si and Ge/Si ratios associated with variable contributions of surface runoff relative to deep active layer leaching. Before the rain event, Zackenberg tributaries did not contribute notably to the solute export of the Zackenberg River, and supra‐permafrost ground waters governed the supply of solutes in Zackenberg tributaries and Grænse stream. After the rain event, surface runoff modified the composition of Grænse stream, and non‐glacial tributaries strongly increased their contribution to the Zackenberg River solute export. Our results show that summer rainfall events provide an additional source of DOM and Si‐rich waters from permafrost‐underlain catchments to the discharge of glacially dominated rivers. This suggests that the magnitude and composition of solute exports from Arctic rivers are modulated by permafrost thaw and summer rain events. This event‐driven solute supply will likely impact the carbon cycle in rivers, estuaries, and oceans and should be included into future predictions of carbon balance in these vulnerable Arctic systems.

Mixing Dynamics Within the Kuroshio Area Are Reflected in Dissolved Inorganic Radiocarbon Values

AbstractKuroshio is an important western boundary current system in the North Pacific subtropical gyre. Mesoscale eddies play an important role in Kuroshio path variations, which significantly affect fisheries, marine navigation, and climate in regions along the Kuroshio path. However, the direct physical impacts of the Kuroshio variabilities on mixing dynamics within the water columns off the southern coast of Japan remain unclear due to the lack of observational records. The radiocarbon (Δ14C) in dissolved inorganic carbon (DIC) of seawater has been used as a reliable tracer of water circulation and mixing processes. Here, we present the high‐resolution dissolved inorganic radiocarbon (DIC ∆14C) measurements for water samples collected during the Kuroshio large‐meander (LM) period in March 2022 to observe the mixing dynamics within the Kuroshio area and elucidate the controls of mixing processes. In the present study, horizontal variations (12–175‰) in DIC Δ14C values were observed between 400 and 1,000 m and were attributed mainly to changes in the depth of isopycnal surfaces associated with mesoscale eddies and the position of the Kuroshio axis. Furthermore, fluctuations in DIC Δ14C values (10–25‰) were observed on the same isopycnal surfaces ( 25.5–27.0), suggesting the occurrence of diapycnal mixing. By comparing this newly obtained data with values previously reported at similar locations, variations in penetration depths of high bomb 14C signals from past observations are found to be mainly caused by changes in the depth of isopycnal surfaces associated with mesoscale eddies and Kuroshio path variations.

SOIL CARBON STOCKS NOT LINKED TO ABOVEGROUND LITTER INPUT AND CHEMISTRY OF OLD-GROWTH FOREST AND ADJACENT PRAIRIE

ABSTRACT The long-standing assumption that aboveground plant litter inputs have a substantial influence on soil organic carbon storage (SOC) and dynamics has been challenged by a new paradigm for SOC formation and persistence. We tested the importance of plant litter chemistry on SOC storage, distribution, composition, and age by comparing two highly contrasting ecosystems: an old-growth coast redwood (Sequoia sempervirens) forest, with highly aromatic litter, and an adjacent coastal prairie, with more easily decomposed litter. We hypothesized that if plant litter chemistry was the primary driver, redwood would store more and older SOC that was less microbially processed than prairie. Total soil carbon stocks to 110 cm depth were higher in prairie (35 kg C m−2) than redwood (28 kg C m−2). Radiocarbon values indicated shorter SOC residence times in redwood than prairie throughout the profile. Higher amounts of pyrogenic carbon and a higher degree of microbial processing of SOC appear to be instrumental for soil carbon storage and persistence in prairie, while differences in fine-root carbon inputs likely contribute to younger SOC in redwood. We conclude that at these sites fire residues, root inputs, and soil properties influence soil carbon dynamics to a greater degree than the properties of aboveground litter.

RADIOCARBON AND URANIUM PROFILES IN MARINE GASTROPODS AROUND THE JAPANESE ARCHIPELAGO

ABSTRACT In this study, we investigate the distribution of radiocarbon and uranium in the calcified opercula of Turbo sp. collected from Ryukyu region and Chiba, Japan, to explore the potential of U/Th dating using mollusks collected from the Japanese archipelago. We acquired high-resolution radiocarbon and uranium concentration measurements using single-stage accelerator mass spectrometry and laser ablation−inductively coupled plasma−mass spectrometry. Our results show that uranium in the opercula of modern Turbo sp. is unevenly distributed at concentrations 1000 times less than those in coral skeletons. Radiocarbon found in the calcified opercula samples record ambient seawater radiocarbon values as well as coral skeletons. Uranium in the calcified opercula of Holocene Turbo marmoratus were also unevenly distributed and concentrated within the opercula in a different manner than observed in modern samples, suggesting uranium exchange after death. Our results suggest variable uptake of uranium isotopes into mollusk shells and highlights the need for rigorous sample selection criteria when choosing mollusks species for U/Th dating around Japan.

Новые данные по радиоуглеродной хронологии неолитических комплексов Виловатовской стоянки

Introduction. The article presents some latest absolute dates for Neolithic pottery from the Vilovatoye site, the latter being characterized by a most impressive pottery collection from the Middle and Late Neolithic across the forest-steppe Volga River basin. Goals. The work shall introduce a series of radiocarbon dates for Neolithic patterns of the Vilovatoye site. To facilitate this, the paper shall describe the vessels that yielded such radiocarbon dates, analyze and interpret the absolute values, compare the latter to those of the Middle Volga culture. Materials and methods. In 2018–2019, shards from a total of fourteen Neolithic vessels excavated in the site of Vilovatoye were selected. Four of them were decorated with pricks of different shapes, one bore pricks combined with blackened lines, and nine vessels had comb stamps. Radiocarbon dating by liquid scintillation was conducted at the Radiocarbon Laboratory of Herzen University. Results. The pricked vessels of the Vilovatoye site dated from the third quarter of the 6th millennium BC to the second quarter of the 5th millennium BC. These results tend to well correlate with dates yielded by pricked pottery of the Middle Volga culture. The shards of the vessel decorated with pricks and blackened lines were dated to the first half of 5th millennium BC. The absolute dates for the comb-imprinted pottery cluster within a vast interval — from the last quarter of the 6th millennium BC to the third quarter of the 5th millennium BC. So, the latter dates also well correlate with available radiocarbon values for comb-ornamented pottery of both the Vilovatoye site and the Middle Volga culture. Conclusions. The newly obtained radiocarbon values shall significantly add to the set of dates for the Middle Volga culture. Those are evidence that the traditions of pricked and comb-stamped pottery somewhat co-existed — on the Vilovatoye site in particular, and within the Middle Volga culture at large.

Ecosystem and soil respiration radiocarbon detects old carbon release as a fingerprint of warming and permafrost destabilization with climate change.

The permafrost region has accumulated organic carbon in cold and waterlogged soils over thousands of years and now contains three times as much carbon as the atmosphere. Global warming is degrading permafrost with the potential to accelerate climate change as increased microbial decomposition releases soil carbon as greenhouse gases. A 19-year time series of soil and ecosystem respiration radiocarbon from Alaska provides long-term insight into changing permafrost soil carbon dynamics in a warmer world. Nine per cent of ecosystem respiration and 23% of soil respiration observations had radiocarbon values more than 50‰ lower than the atmospheric value. Furthermore, the overall trend of ecosystem and soil respiration radiocarbon values through time decreased more than atmospheric radiocarbon values did, indicating that old carbon degradation was enhanced. Boosted regression tree analyses showed that temperature and moisture environmental variables had the largest relative influence on lower radiocarbon values. This suggested that old carbon degradation was controlled by warming/permafrost thaw and soil drying together, as waterlogged soil conditions could protect soil carbon from microbial decomposition even when thawed. Overall, changing conditions increasingly favoured the release of old carbon, which is a definitive fingerprint of an accelerating feedback to climate change as a consequence of warming and permafrost destabilization. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'.

Testing the potential of Serpulidae tubes as an indicator of past relative sea-level collected from shored wave dissipating blocks along the Pacific and Japan sea coast of northeastern Japan

Relative sea-levels (RSL) in the past can be used to understand crustal movements, as paleo-shoreline elevations can be modified by seismic activities [1]. To assess short-term crustal movements, reliable RSL proxies are key in age determination to derive precise tectonic activities. The Tohoku region in northern Japan has complex oceanographic setting since two currents, cold Oyashio and warm Kuroshio being merged in the region. Here, we assessed the potential of Hydroides ezoensis (HE), as a new proxy of RSL. The 14C concentrations of HE collected in the Tohoku region were measured and compared with previous studies that reported radiocarbon values of the surface ocean. Results showed HE possesses summer surface 14C. This suggests that HE is suitable to be used as a reliable RSL proxy that can reliably provide age information without having influences from radiocarbon depleted Oyashio. Thus, HE could be used as a reliable proxy to understand paleo-RSL.

Carbon mobilization in response to the 2021 Mw 7.4 Maduo earthquake: Constraints from carbon isotope systematics of subsurface fluids

Active fault zones provide favorable channels for the discharge of carbon-bearing fluids from Earth’s interior. Earthquakes, as a common fault-related dynamic process, can disturb the circulation of subsurface fluids and their interactions with country rocks and sediments on short timescales, which may cause changes in carbon mobilization processes and carbon sources of the discharged fluids. However, quantitative research on earthquake-induced changes in carbon mobilization at deep and shallow levels remains lacking. Here, we present a quantitative study on stable carbon isotopes (δ13C) and radiocarbon values (Δ14C) of dissolved inorganic carbon (DIC) in subsurface fluid samples from the surface rupture zone formed by the Mw 7.4 Maduo earthquake (22 May 2021) and the East Kunlun fault, NE Tibetan Plateau. Our results show that δ13CDIC values vary from –11.6‰ to 0.1‰, while Δ13CDIC values have a range of –980‰ to –46‰. Using a mass balance model based on δ13CDIC and DIC concentrations, we calculated the proportions of source components involved in DIC, including organic carbon, carbonates, and deeply-sourced carbon. On average, waters discharging from the surface rupture zone have higher inputs from organic carbon (28.1%) than those from the East Kunlun fault (18.6%), with the latter showing higher deeply-sourced carbon contributions (45.7% vs. 30.7%). This is consistent with the lower average Δ14CDIC value (–544‰) observed from the East Kunlun fault, suggesting more inputs from carbon source components that are devoid of 14C (i.e., deeply-sourced carbon and carbonates). These findings indicate that seismic events can significantly affect the carbon mobilization processes at variable depths, especially the shallow soil organic carbon in the case of the 2021 Maduo earthquake. The potential effects of earthquake-induced changes in carbon mobilization processes should be taken into account in the modeling of tectonic carbon dioxide degassing and carbon cycle on longer timescales.

Sedimentary Accumulation of Black Carbon on the East Coast of The United States

AbstractThe occurrence, trends and sources of soot black carbon (BC) in coastal sediments are poorly understood, particularly during the Anthropocene. Two sediment cores, covering the last ∼100 years from the US East Coast, off North Carolina and in the Florida Straits, were analyzed for organic carbon (OC), BC fluxes and BC sources. BC fluxes were 0.1 g cm−2 year−1 at both sites and accounted for 8%–22% of total OC. Carbon stable isotope values indicated OC to be of marine origin, while the BC was mostly terrestrially derived, C3‐plant material. Radiocarbon values revealed BC originating mostly from fossil fuels or pre‐aged carbon (fraction modern of 14%–31%) at North Carolina, while in the Florida Strait the BC was mostly derived from biomass burning (fraction modern of 70%–74%), in‐line with continental (NC) or marine (FS) air mass origins. Ratios of polycyclic aromatic hydrocarbons broadly supported different BC sources at the two sites.

Seasonal variation of surface seawater radiocarbon in the Andaman Sea as recorded in coral

Corals provide high-resolution radiocarbon record of the surface ocean. These high-resolution records can provide understanding of the surface ocean conditions and processes regulating these conditions. A Porites coral from the Andaman Sea was investigated for its high-resolution radiocarbon record between 2007 and 2014. The radiocarbon measurement of the coral shows a post-bomb period decline trend (2.7‰ yr−1) along with seasonal variations. A positive correlation is observed between the seasonal radiocarbon changes and the stable oxygen isotope values of the coral. The coral registers the seasonal changes in mixed layer depth and sea surface temperature between the monsoon and non-monsoon periods. Recent radiocarbon values of the Andaman Sea surface water have been found to be higher compared to the contemporary atmospheric radiocarbon values.

Development of graphitization method for low carbon aerosol filter samples with Automated Graphitization System AGE-3

The wide applications of the radiocarbon (14C) approach in environmental, archeological, and geological research often necessitates the analysis of microgram-sized samples. The ability to measure low carbon samples is particularly relevant for aerosol particle filters, especially for samples from pristine environments. For this purpose, we investigated the sample dilution method for graphitization of low-carbon samples (20–200 μg C) with an Automated Graphitization System (AGE-3), and applied a mass balance equation for the calculation of 14C values. Materials with known 14C values (standards NIST-OXII and IAEA-C7) were diluted with 14C-free phthalic anhydride (PhA) until sufficient mass (500 μg C) for graphitization with the AGE-3 system was acquired. Reliable 14C values were obtained for samples with carbon amount in the range of 40–200 μg. Next, we adapted the dilution method for estimation of aerosol sample 14C values. Using it, we attained a precision of 0.71 ± 0.83 pMC for 14C measurements of aerosol samples containing 40–200 μg C. A shift of radiocarbon values to 5.07 pMC (average 3.08 ± 1.7 pMC) was observed for samples with low carbon content (<20 μg C). We determined that a precision of 2–3 pMC is acceptable for aerosol particle source apportionment studies. Using the sample dilution method, graphitization with AGE-3 of aerosol samples with carbon content >40 μg becomes a viable and efficient way of sample preparation for 14C analysis.

Sources and Cycling of Particulate Organic Matter in Baffin Bay: A Multi-Isotope δ13C, δ15N, and Δ14C Approach

The Canadian Arctic is warming three times faster than the rest of the planet. The impact of climate change on the Arctic carbon cycle, and in particular for Baffin Bay, remains poorly constrained. Sinking particulate organic matter (POMsink) is a key component of the biological carbon pump and provides a direct linkage between surface productivity and the preservation of carbon in marine sediments. While POMsink provides a rapid POM shunt to the deep ocean (days) the majority of marine POM is suspended (POMsusp) persists for years in the water column. Stable carbon (δ13C), nitrogen (δ15N) and radiocarbon (Δ14C) measurements are powerful tools for evaluating sources and cycling of POM. In this study, we measure depth-integrated (0-400m) POMsusp stable carbon (δ13C), nitrogen (δ15N) and radiocarbon (Δ14C) values at 11 stations in Baffin Bay. We use POM C:Na ratios to evaluate its diagenetic state. POMsusp δ13C and δ15N values ranged from −21.6‰ to −29.5‰, and +3.84‰ to +7.21‰, respectively. POMsusp Δ14C values ranged from −41.8‰ to +76.8‰. Together, our results suggest Baffin Bay POMsusp has multiple carbon and nitrogen sources. POMsusp δ13C and Δ14C are strongly correlated to surface salinity, indicating surface water has a strong influence on POMsusp isotopic composition and 14C-age. POMsusp from coastal Greenland stations have similar Δ14C values to surface dissolved inorganic carbon (DIC) and POM concentrations, consistent with primary production as the predominant POMsusp source in Eastern Baffin Bay. Positive POMsusp Δ14C values in central Baffin Bay suggest an accumulation of atmospheric “bomb” 14C in the sub-polar gyre. POMsusp exiting Davis Strait via the Baffin Island Current was determined to have a significant degraded, resuspended sediment component. Finally, POMsusp δ15N values highlight two distinct N sources in Baffin Bay: Pacific and Arctic nutrients at Northern gateway stations vs. the influx of Atlantic nutrients via Davis Strait along coastal Greenland. Overall, these first Baffin Bay POMsusp Δ14C values provide useful baseline data for rapidly changing Arctic ecosystem.

Using Radiocarbon Measurements of Dissolved Inorganic Carbon to Determine a Revised Residence Time for Deep Baffin Bay

The Canadian Arctic is warming at three times the rate of the rest of the planet and the effects of climate change on the Arctic marine carbon cycle remains unconstrained. Baffin Bay is a semi-enclosed, Arctic basin that connects the Arctic Ocean to the north to the Labrador Sea to the south. While the physical oceanography of surface Baffin Bay is well characterized, less is known about deep water formation mechanisms within the Basin. Only a few residence-time estimates for Baffin Bay Deep Water (BBDW) exist and range from 20 to 1450 years. Better residence time estimates are needed to understand the oceanographic significance of Baffin Bay. Here we report stable carbon (δ13C) and radiocarbon (Δ14C) values of dissolved inorganic carbon (DIC) collected aboard the CCGS Amundsen in 2019. DIC δ13C and Δ14C values between ranged between -0.7‰ to +1.9‰ and -90.0‰ to +29.8‰, respectively. Surface DIC δ13C values were between +0.7‰ to +1.9‰, while deep (&amp;gt;100m) values were 0.0 to -0.7‰. Surface DIC Δ14C values ranged between -5.4‰ to +22.9‰, while deep DIC (&amp;gt;1400m) DIC Δ14C averaged -82.2 ± 8.5‰ (n = 9). To constrain natural DIC Δ14C values, we quantified the amount of atmospheric “bomb” 14C in DIC (Δ14Cbomb; using the potential alkalinity method; Palk) and anthropogenic DIC (DICanth; using the ΔC* method). Both proxies indicate an absence of Δ14Cbomb and DICanth below 1000m. Using two previously proposed deep water formation mechanisms and our corrected DIC Δ14Cnatural values, we estimated a 14C-based residence time of 360-690 years for BBDW. Based on these residence times, we infer carbon is likely stored for centuries in deep Baffin Bay.

Lag time of modern bomb-pulse radiocarbon in human bone tissues: New data from Brazil

Radiocarbon analysis with reference to the modern bomb-curve was conducted using 68 bone samples of a vertebral body, femoral diaphysis, occipital bone, and parietal bone of 17 adults from Brazil. All individuals were born in 1963, thus analysis focused on the correlation with atmospheric values during the more recent, falling portion of the curve. Ages at death ranged from 43 to 54 years with representation of both sexes. Lag time (difference between the actual death date and the year of correspondence of the radiocarbon value with the curve) was evaluated for each individual and each tissue. The mean of the lag time values was 20.2 years, and the median was 22.0 years. The femur had the highest lag time median (29.5 years) among the bone groups, followed by the occipital (25.5 years), parietal (23.5 years) and the vertebra (8.0 years). The same pattern was observed for both sexes, but females tended to have lower lag time values than males. Different tissues presented considerable variation in lag time with vertebral bodies the least and the femoral diaphysis the greatest. These data suggest that individual age at death and the associated lag time must be considered in estimating the approximate death date. The lag time values for vertebral bodies were lower and with less variability in comparison with values for the occipital, parietal, and femur indicating greater consistency of that bone group for time since death estimation in the studied sample.

REAL BURIALS OR CENOTAPHS? A STUDY OF THE MYSTERIOUS UNDER-MOUND FUNERARY CONSTRUCTIONS OF THE TRZCINIEC CULTURAL CIRCLE

The purpose of this article is to present a complex analysis of recently recognised funeral structures discovered in Trzciniec Cultural Circle barrows. These features are rectangular and stones are typically situated in the corners, in the middle of the sides, or along the walls, creating unique structures with clearly delineated interior spaces. However, the function of these features is not well understood. This feature form is fragile and slight, which makes them difficult to record using traditional excavation methods. The majority of these features have been discovered over the last decade now that new documentation and exploration tools are available to archaeologists. These constructions are only known from barrow cemeteries and the remains of in situ cremation were also documented in their context. Their occurrence confirms the variety and complexity of funeral rites of the Trzciniec Cultural Circle community. To date, eight structures of this type are known. Four (Barrow 1/I/2010 — Feature 3; Barrow 7/I/2014 — Features 6 and 7; Barrow 2/I/2010/2012 — Feature 1) were registered in the Bukivna cemetery during the Polish-Ukrainian expedition realized by scholars from Adam Mickiewicz University in Poznań, the National Academy of Sciences of Ukraine in Kiev, and Vasyl Stephanyk Precarpathian University in Ivano-Frankivsk. The study of archival materials from pre-war excavations conducted by T. Sulimirski and J. Grabowski in Komariv revealed another three features of this type (Barrow 34 — Features A and B; Barrow 45 — Feature 1). One structure of this type (Grave 2) was also excavated in Nieciecz Włościańska in the northeast enclave of the Trzciniec Cultural Circle during recent investment research.&#x0D; Due to radiocarbon analysis, the authors have securely established the chronology of these features. The obtained radiocarbon values indicate that these constructions were erected during the classic stage of the Trzciniec Cultural Circle, attributable to the 18 to 16th centuries BC, which was confirmed by archaeological material found within these features.&#x0D; The discussion of the function and symbolism of these constructions suggest that they could play the role of burials. This is also suggested by geochemical analysis of soil samples from the Bukivna cemetery. However, due to the lack of osteological material in most of these features, this aspect remains shrouded in mystery and requires additional studies. Regardless, the form, location in barrows, and funerary inventory of these features suggest that they played important role in funeral rites of the Trzciniec Cultural Circle society.

The Reservoir Age Effect Varies With the Mobilization of Pre-Aged Organic Carbon in a High-Altitude Central Asian Catchment

Lake sediments provide excellent archives to study past environmental and hydrological changes at high temporal resolution. However, their utility is often restricted by chronological uncertainties due to the “reservoir age effect” (RAE), a phenomenon that results in anomalously old radiocarbon ages of total organic carbon (TOC) samples that is mainly attributed to the contribution of pre-aged carbon from aquatic organisms. Although the RAE is a well-known problem especially in high altitude lakes, detailed studies analyzing the temporal variations in the contribution of terrestrial and aquatic organic carbon (OC) on the RAE are scarce. This is partially due to the complexity of isolating individual compounds for subsequent compound-specific radiocarbon analysis (CSRA). We developed a rapid method for isolating individual short-chain (C16and C18) and long-chain (&amp;gt;C24) saturated fatty acid methyl esters (FAMEs) by using high-pressure liquid chromatography (HPLC). Our method introduces only minor contaminations (0.50 ± 0.22 µg dead carbon on average) and requires only few injections (≤10), therefore offering clear advantages over traditional preparative gas chromatography (prep-GC). Here we show that radiocarbon values (Δ14C) of long-chain FAs, which originate from terrestrial higher plant waxes, reflect carbon from a substantially pre-aged OC reservoir, whereas the Δ14C of short-chain FAs that originate from aquatic sources were generally less pre-aged.14C ages obtained from the long-chain FAs are in closer agreement with14C ages of the corresponding bulk TOC fraction, indicating a high control of pre-aged terrestrial OC input from the catchment on TOC-derived14C ages. Variations in the age offset between terrestrial and aquatic biomarkers are related to changes in bulk sediment log(Ti/K) that reflect variations in detrital input from the catchment. Our results indicate that the chronological offset between terrestrial and aquatic OC in this high-altitude catchment is mainly driven by temporal variations in the mobilization of pre-aged OC from the catchment. In conclusion, to obtain accurate and process-specific lake sediment chronologies, attention must be given to the temporal dynamics of the RAE. Variations in the apparent ages of aquatic and terrestrial contributions to the sediment and their mass balance can substantially alter the reservoir age effect.