Search Results (298)

Radiocarbon (¹⁴C) serves as a unique physical tracer for fossil fuel CO₂ (CO_2ff) owing to its absence in ancient fuels. This review synthesizes methodologies and applications of ¹⁴C in quantifying CO_2ff emissions from urban to regional scales. It outlines the theoretical framework for partitioning CO_2ff from other sources using Δ¹⁴C and summarizes advances in sampling strategies and accelerator mass spectrometry (AMS) analysis. Key methodological challenges—including disequilibrium fluxes from terrestrial and oceanic reservoirs, sparse observational networks, and uncertainties in atmospheric inversion models—are critically assessed. The review highlights the pivotal role of ¹⁴C in independently verifying rapid, policy-driven emission reductions during the COVID-19 lockdowns, which provided a clear signal distinct from natural variability. Case studies, with a particular focus on China, demonstrate its utility in tracking spatial gradients and long-term trends. Looking forward, synergistic pathways that integrate multi-tracer observations, expanded monitoring networks, and enhanced modeling are discussed to strengthen the role of ¹⁴C within a comprehensive CO_2ff monitoring and verification framework. Full article

Radiocarbon dating of lead white has progressed considerably in the last decade. Today, the protocol enables the analysis of various types of samples: pure lead white in cosmetics, ancient and modern paint layers containing lead white and oil, and mixtures of lead white and calcite. However, it has also been shown that the presence of a large amount of calcite in lead white paint can alter the radiocarbon result through contamination with dead carbon. To overcome this problem, careful characterization of samples must be carried out prior to dating. Lead white paint layers from the Queen’s apartment at the Palace of Versailles were observed by electronic microscopy and analyzed by Synchrotron X-ray-based diffraction to discriminate the different layers of paint in order to minimize contamination. Chemical analysis and ¹⁴C dating were used to document the implementation of the decorations in Queen Marie-Antoinette’s library. Full article

Relics and mortal remains attributed to saints and martyrs, long venerated within Christian tradition, represent a unique area of scientific inquiry conducted under canonical procedures aimed at verifying authenticity, ensuring preservation, and promoting public devotion. This study focuses on the canonical recognition of the bone remains preserved in the Specus Martyrum of Atripalda (ancient Abellinum), attributed to Saint Hipolystus and the martyrs Crescentius and Irenaeus. The investigation was promoted by the Diocese of Avellino in preparation for the Hipolystian Jubilee commemorating 1720 years since their martyrdom (1 May 303 A.D.). A multidisciplinary approach was applied, combining historical analysis of sources such as the Martyrologium Hieronymianum (5th century), the Passio Sancti Hipolysti (9th century, edited in the Acta Sanctorum) and another Passio written by the Bishop Ruggero (13th century), with anthropological, radiographic, and radiocarbon (¹⁴C) analyses. The skeletal remains were examined through recognition, lateralization, cataloging, and evaluation of morphological and anthropometric features. The results identified elements compatible with an elderly male and two subadult individuals, consistent with the traditional identities of the martyrs. Despite the challenges posed by commingling, fragmentation, and environmental degradation, the investigation demonstrated how scientific rigor can effectively support canonical processes, offering a methodological framework for the verification of relics and contributing to the preservation of religious and cultural heritage. Full article

Today’s fluvioscape of the Hessische Ried (Upper Rhine Graben) is the consequence of human intervention on the natural drainage system that has transformed a large floodplain into an intensively used cultural landscape. Already, the Romans carried out river regulation and water management to guarantee the transportation of material and troops, securing the territory of the Roman Empire. To secure the so-called Rhein-Limes, burgi (fortlets) were constructed along small tributaries of the River Rhine under Valentinian I. (364–375). The burgus at Trebur-Astheim represents such a military site. It is located at the Schwarzbach/Landgraben fluvial system, which was actively used as a waterway and connected important military sites such as the castra “Auf Esch” (Groß-Gerau) with the River Rhine and, thus, with the provincial capital Mogontiacum (Mainz). Using a combination of magnetic gradiometry, frequency domain electromagnetic induction (FDEMI), electrical resistivity tomography (ERT), direct push-sensing (DP), and sediment coring, we were able to detect a 15 m wide and 2.5 m deep Roman canal between the burgus at Trebur-Astheim and the River Rhine, opening the Hessische Ried hinterland to wider trade routes. Radiocarbon dating further reveals that after a final re-excavation, the channel started to silt up in the 7th/8th century AD and finally fell out of use. This last period of use may be associated with the activities of the Carolingian Königspfalz (royal palace) Trebur. Our study shows that the fluvioscape of the Hessische Ried dates back to Roman times and that the canal at Trebur-Astheim is one of the few navigable canals known to have existed north of the Alps during the Roman period and the Early Middle Ages. Full article

This research provides a new comprehensive assessment of Pikimachay Cave fossil remains of extinct fauna from the Late Pleistocene and Early Holocene, curated in the Florida Museum of Natural History’s Environmental Archaeology Program collections. The collection is the result of excavations carried out by Richard MacNeish during the 1960s and 1970s, during which he proposed pre-Clovis dates for human occupation in South America. Archival records housed across three institutions were compiled to reconstruct the spatial distribution of megafauna within the cave. Taphonomic observations of the bone assemblage were conducted to better understand depositional processes and cave conditions. Based on the spatial distribution of fossil evidence mapped and documented by layer and the taphonomic evidence of the bone assemblage, we conclude that the cave functioned primarily as a giant ground sloth burrow, also used by humans and carnivores. Future research, including additional radiocarbon dates and better contextualization of the deposits, will be essential for better understanding the fossil fauna represented in the cave and the ecological relationships among humans, carnivores and extinct species in the highlands of Perú. Full article

This study re-evaluates the hydrogeological framework of the Bohemian Cretaceous Basin (Czech Republic), where preliminary surveys unexpectedly identified old groundwater in several springs and abstraction wells. Traditional distinction into a Cenomanian (A) and a single Turonian (C) aquifer failed to explain the observed hydraulic head discrepancies and the occurrence of old groundwater. By integrating the spatial correlations of hundreds of well logs with hydraulic head data, environmental tracers (chemistry, ²H, ³H, ¹³C, ¹⁴C, ¹⁸O, ³⁹Ar, ⁸⁵Kr, CFCs, SF₆, and noble gases), and field measurements, we objectively delineated the hydrostratigraphic architecture of the basin. The results demonstrate three distinct aquifers (A, Ca, and Cb), challenging long-standing interpretations. Several flow systems were identified, with mean residence times of the old water exceeding 300 years. The hydrogeochemical and isotopic evidence confirmed mixing of Holocene groundwater between Ca and Cb aquifers while excluding Last Glacial Period fossil groundwater that is typical of the A aquifer. These findings highlight the necessity of a multi-proxy approach to validate conceptual models in seemingly “well-understood” regions. The newly characterized subdivision of Turonian aquifers is critical for protecting old groundwater resources, optimizing the design of geothermal and water supply wells to prevent hydraulic short-circuiting, and identifying previously unrecognized groundwater resources currently discharging to the Jizera River. Full article

This study explores the hydrochemical and thermal characteristics of a fault-controlled geothermal field within the Northern Qinghai Lake Coalfield Area on the northeastern Qinghai–Tibetan Plateau (QTP). This research integrates hydrochemical analyses, isotopic tracers, and the regional geological framework to define hydrochemical signatures, identify recharge sources and flow paths, assess cold–hot water mixing, estimate reservoir temperatures, determine circulation depths and residence times, and explain the geothermal system’s formation. Systematic sampling included geothermal waters, cold springs, and surface waters, followed by laboratory analysis of major ions, stable isotopes (δ²H, δ¹⁸O), radiocarbon (¹⁴C), and tritium (³H). The geothermal water is categorized as a low-temperature, weakly acidic to near-neutral HCO₃-Ca•Mg type, exhibiting temperatures from 35.6 to 46.2 °C. Isotopic analyses indicate that cold spring and river waters align with the local meteoric water line, while geothermal waters display distinct isotopic signatures, suggesting deeper circulation. A silica–enthalpy mixing model reveals substantial cold-water mixing during upwelling, with mixing ratios between 74.5% and 85.6%. The corrected recharge elevation is estimated to be 4378–4456 amsl, implying a primary recharge zone in the branch of the Qilian mountains—the middle section of Datong Mountain to the northeast. Geothermometry, employing quartz and chalcedony temperature scales and accounting for mixing, estimates reservoir temperatures of 150–202 °C. The calculated circulation depth spans 3211–4291 amsl. Low tritium levels and carbon dating suggest a deep-cycling system predating 1952, characterized by deeply circulating “ancient water”. The geothermal system’s development is associated with regional tectonics, fault systems, and the Kesuer Formation (J_xk) acting as the reservoir. This study provides a scientific foundation for the development and sustainable use of geothermal resources in the northern Qinghai Lake region and offers insights applicable to comparable fault-controlled geothermal systems across the QTP. Full article

This study presents a multiproxy paleoecological reconstruction from Laguna El Cacahuate, located ~180 km inland in the floodplain of Tabasco, southeastern Mexico, where red mangrove (Rhizophora mangle L.) forms persistent forest stands under freshwater conditions. We analyzed a 180 cm sediment core using pollen analysis, X-ray fluorescence geochemistry, and radiocarbon dating to investigate the environmental drivers of inland mangrove expansion. The core spans the last ~5200 years, capturing major shifts in vegetation and hydroperiod change. During the mid-Holocene, herbaceous freshwater taxa (Poaceae, Cyperaceae) dominated the floodplain under variable hydroclimatic conditions and high clastic input. The appearance of Rhizophora mangle pollen around 750 cal yr BP marks a significant ecological transition coinciding with geochemical indicators of stabilized flooding and reduced sedimentation. This inland colonization aligns temporally with increased regional precipitation and possible hydrogeomorphic changes following the 13th-century Plinian eruption of El Chichón. Unlike coastal mangroves, the persistence of Rhizophora under freshwater conditions supports the interpretation of this species as a facultative halophyte and indicates high resilience to long-term hydrological shifts. These findings provide critical insight into the ecological plasticity of mangroves, the paleoenvironmental history of the lower Usumacinta–San Pedro Basin, and the importance of integrating long-term records for wetland conservation strategies under future climate scenarios. Full article

Saltmarshes have emerged as important sinks for microplastic (MP) pollution, yet little is known about the long-term accumulation and retention mechanisms of MPs in these environments. This study presents the first chronological record of MPs in Mediterranean saltmarsh sediments, using sediment cores dated via a combination of AMS radiocarbon (¹⁴C) and radionuclide (²¹⁰Pb, ¹³⁷Cs, ²⁴¹Am) from two saltmarshes located on the Adriatic Sea coast of Croatia (Blace and Jadrtovac). MPs were extracted and analysed across core depths and assessed in relation to geochemical parameters (organic matter (OM), carbonates, organic carbon (C-org), total nitrogen (TN), phosphorus (P) forms’ content, and grain size distribution). Results show that MPs first appear in sediments dated to 1950 in Jadrtovac and post-1960 in Blace, with concentrations increasing markedly in more recent surface layers. Jadrtovac exhibited higher MP concentrations (up to 0.5 MPs g⁻¹), dominated by fibres (86%) associated with urban and maritime sources, while Blace showed lower concentrations, dominated by fragments (60%), likely from localised sources such as agriculture or single-use packaging. Polymer analysis confirmed contrasting source profiles, with rayon and cellophane dominating in Jadrtovac, and polypropylene and olefin in Blace. MPs positively correlated with OM, C-org, P, TN and sand content, and negatively with clay and carbonate content. Principal component analysis (PCA) confirmed that MPs were associated with organic-rich, sandy sediments. These findings demonstrate that OM composition and sediment texture significantly influence MP retention and highlight the role of saltmarshes as long-term archives of plastic pollution in low-energy coastal settings. Full article

The exploration of Doggerland, the prehistoric landscape that once connected Britain to the continent, remains one of Europe’s most significant archeological challenges. This paper presents a study into the palaeolandscape and the paleoenvironmental development of Doggerland, through the geochemical analyses of a core (ELF019) taken from the southern North Sea. The thermal properties divided the core into three sedimentary zones based on the variations in organic matter and carbonate content. Organic biomarkers were used to distinguish between terrestrial and aquatic vegetation inputs, revealing alternating freshwater, terrestrial, and marine input influences. Chemostratigraphy defined six depositional zones that corresponded with the identified thermal and biomarker data. Radiocarbon dating of peat-derived humic fractions anchored the key environmental transition between freshwater and saline deposition to the Greenlandian period of the Lower Holocene (10,243–10,199 Cal BP). The integrated geochemical evidence suggests a transformation from freshwater silts, low organic content, and sandy clay deposit to saline clay marine deposit. The progressive transformation may reflect the inundation sequence that led to the final submergence of Doggerland. Full article

This commentary re-evaluates the study by Makó et al. which reconstructs dust accumulation rates from loess–paleosol sequences in the Carpathian Basin. Several methodological and factual issues substantially limit the reliability of their interpretations. The study reports linear sedimentation rates (mm a⁻¹) as mass accumulation rates (MARs) without accounting for bulk density, rendering their values non-comparable with established MAR datasets. It also overlooks a documented systematic bias between ¹⁴C and luminescence-derived MARs which are shown to differ by a factor of nearly three in Perić et al., a directly relevant synthesis that is not cited. Furthermore, the conflation of distinct sites (Surduk and Veliki Surduk) and the incorrect attribution of the Surduk section’s location indicate errors in basic site metadata. Together, these issues suggest that the reported “high accumulation axis” may reflect methodological artefacts rather than genuine environmental gradients. Improved methodological transparency and consistency are essential for robust regional reconstructions. Full article

This research investigates ten sediment cores extracted from Holocene deposits in Labu, northern Temburong District, Brunei Darussalam, to provide an initial inventory of the encountered peat-forming environments. Proximate, ultimate, and geochemical analyses were performed, along with mineralogical characterisations and ¹⁴C radiocarbon dating, as well as preliminary palaeontological and palynological examinations of the peat and underlying substrate layers. Localised organic deposits, termed “peat pockets”, were identified, with the oldest found to have begun accumulating under topogenous-mire conditions during the Middle Holocene. This coincides with the Mid-Holocene sea-level rise, which is thought to have peaked at 6000–4500 years BP. However, our data suggest that sea level may have continued rising until approximately 2500 years BP, peaking between 2500 and 1700 years BP, followed by delta progradation in Temburong. These “peat pockets” gradually coalesced into larger topogenous mires associated with estuarine environments. Over time, they became less influenced by marine conditions and increasingly shaped by a freshwater regime, resembling an upper delta system, similar to the present-day landscape observed in Temburong. It is proposed that these mires transitioned from a topogenous to an ombrogenous phase approximately 250 to 320 years BP, as inferred through forward age extrapolation based on a constant accumulation rate. The findings support the hypothesis of inland coastline migration during the Middle Holocene, followed by retraction due to deltaic progradation in the Late Holocene. These fluctuations align with well-established sea-level changes driven by climatic variability. Full article

The Archaic period in the Maya lowlands of Mesoamerica emerged around 8000 BCE and likely lasted until about 1000 BCE; however, both the development and complex cultural adaptations representative of Archaic peoples present challenges for archaeologists. In central Belize, archaeological evidence for Archaic people is limited, especially when compared to northern and southern Belize. Nevertheless, our knowledge of Archaic lifestyles in this part of the world has substantially increased over the last twenty years or so. This paper reviews the current understanding of the Archaic period in central Belize based primarily on radiocarbon dates from stratigraphic excavations, diagnostic lithic artifacts, and both faunal and floral remains recovered from excavations, and compares these data to archaeological evidence from northern and southern Belize for regional contextualization and synthesis. Although some aspects of Archaic lifestyles in central Belize appear quite clear based on the available archaeological evidence, others remain elusive. More regional surveys to find sites and an increased number of excavations with datable stratigraphic contexts are needed to more accurately reconstruct the lives of the people who initially inhabited central Belize prior to the emergence of the first culturally recognizable Maya. Full article

This study presents a comprehensive digital workflow for the archaeological investigation and heritage enhancement of the Coëby megalithic necropolis (Brittany, France). Dating to the Middle Neolithic, between the 4th and 3rd millennia BC, this chronology is established through stratigraphy, material culture, and radiocarbon dating. Focusing on cairns TRED 8 and TRED 9, which are two excavation units, we combined field archaeology, photogrammetry, and topographic data with open-source 3D geometric modeling to reconstruct the monuments’ original volumes and test construction hypotheses. The methodology leveraged the free software Blender (version 3.0.1) and its Bagapie extension for the procedural simulation of lithic block distribution within the tumular masses, ensuring both metric accuracy and realistic texturing. Beyond static reconstruction, the research explores innovative dynamic and narrative visualization techniques. We employed the FILM model for smooth video interpolation of the construction sequences and utilized the Wan 2.1 AI model to generate immersive video scenes of Neolithic life based on archaeologically informed prompts. The entire process, from data acquisition to final visualization, was conducted using free and open-source tools, guaranteeing full methodological reproducibility and alignment with open science principles. Our results include detailed 3D reconstructions that elucidate the complex architectural sequences of the cairns, as well as dynamic visualizations that enhance the understanding of their construction logic. This study demonstrates the analytical potential of open-source 3D modelling and AI-based visualisation for megalithic archaeology. Full article

The age of the first construction of the churches of Nuestra Señora de las Viñas (Quintanilla de las Viñas, Burgos), Santa María de Rute (Ventas Blancas, La Rioja), and San Juan Bautista (Barbadillo del Mercado, Burgos) of the northern Iberian Peninsula has been subject to debate for decades. Some scholars date the construction of the churches to the Visigothic period (6th and 7th centuries), while others attribute them to the early Middle Ages (9th and 10th centuries). To shed light on this controversy, the ¹⁴C dating of the binder fraction of mortars of the earliest construction phases was carried out. To determine the suitability of the mortars for ¹⁴C dating, the mineral composition of the binder was determined by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Samples were dated using ¹⁴C Accelerator Mass Spectrometry (AMS). Binder mineralogy precludes some samples from radiocarbon dating. Radiocarbon dating of the Nuestra Señora de las Viñas mortars yielded ages of 534–640 cal AD and 584–658 cal AD. Santa María de Rute yielded ages of 564–650 cal AD, corresponding to Visigothic ages. The San Juan Bautista sample yielded an age of 876–995 AD, although a mortar stratigraphically below results was not suitable for dating. Full article