In the present study, sedimentation conditions and rates in Lake Pleshcheyevo (Yaroslavl region, Central part of the East European Plain) over the past 3600 years were reconstructed based on lithological, geochronological, isotopic, and paleobiological studies of bottom sediments from the deep part of the lake. C/N ratio analysis was used to identify the sources of organic carbon in the lake bottom sediments. Studies of anthropogenic indicators in pollen spectra provided a qualitative comparison of the two age–depth models. Deepwater mesotrophic to eutrophic sedimentation conditions were established during the epoch of cattle farming, 3600–2700 cal yr BP (1600–750 BCE), with relatively high (up to 0.04–0.05 g cm−2 year−1) mass accumulation rates (MAR) corresponding to period of high fluvial activity on the East European Plain. About 1900 cal yr BP (since the beginning of the 1st century CE), with the spread of slash-and-burn agriculture, lake eutrophication occurred, with an increase in sedimentation rates associated with deforestation and ploughing of territories. From 1300 to 200 cal yr BP (7th to the 19th century CE), sedimentation rates decreased. A sharp (up to 0.07 g cm−2 year−1) increase in MAR from the end of the 19th century to the middle of the 20th century was established. Similar trends are typical of lakes within the developed areas and are associated with expansion of cultivated agricultural land.
The subsistence economy of Early Iron Age communities in the Lower Danube remains insufficiently documented despite the large number of settlements attributed to the Babadag culture. This study examines subsistence practices at the eponymous Babadag settlement by combining archaeozoological, carpological, phytolith, and radiocarbon evidence from legacy excavation materials. The chronological framework includes 14 radiocarbon determinations, which broadly support an occupation between the end of the 11th/beginning of the 10th century BC and mid-8th century BC. The analysed assemblages comprise 11,475 faunal remains, two samples of charred plant macroremains, and nine sediment samples for phytolith analysis. Domestic mammals dominate the faunal assemblage, especially cattle and sheep/goat, with fishing providing an important supplementary food resource while hunting remained limited. Age-at-death data, together with the limited sex-ratio evidence, are consistent with mixed livestock exploitation, which may have included meat production, dairying, traction, wool production, and reproduction. Carpological remains document hulled barley, emmer, spelt wheat, and common millet, while phytoliths indicate repeated inputs of grass material into archaeological deposits. Overall, the evidence indicates a diversified subsistence economy based primarily on animal husbandry and cereal cultivation and processing, supplemented by fishing and the limited use of wild resources.
The Stone Age marked the extensive use of rocks for tool-making, with flint as the primary material. However, prehistoric communities, ranging from the Early Lower Paleolithic to the Holocene, also utilized other stones like quartz due to their availability and suitability for manufacturing tools. Quartzose raw materials (quartz and quartzite) were widely exploited during prehistory, particularly in contexts where flint or other sources were scarce or unavailable. However, there are recorded findings of quartz tools from sites located in areas where flint sources were effectively accessible and exploited, such as at the Early Middle Paleolithic (EMP) site of Coudoulous I. This site presents a good opportunity to discuss the subsistence strategies and raw material procurement of Neanderthals in southwestern France and to explore methodological considerations related to the analysis of quartz assemblages. We examined 79 quartz and quartzite artifacts from layer 4 of a bone bed dating back to Marine Isotope Stage 6 (MIS 6), employing optical and digital microscopy along with a comprehensive reference collection. As a result, it was the most commonly identified activity. The hunting-oriented nature of the site is further supported by the limited evidence of other activities, apart from a few instances of scraping or cutting wood and dry hide, which are likely associated with the creation and maintenance of the tools used for hunting. Additionally, some quartz and quartzite artifacts with convergent edges display wear patterns consistent with their use as spear points. Therefore, the lithic industry at Coudoulous I highlights the significance of quartz and quartzite in EMP subsistence strategies and indicates that quartzose materials should not be undervalued or dismissed as opportunistic behavior.
Quaternary carbon-budget reconstructions combine gas observations with groundwater chemistry and dated carbonate deposits, which record different compartments and timescales. We examine the equilibrium partitioning step underlying such interpretations using an independent ideal-dilute calculation and 95 PHREEQC (pH–redox–equilibrium in C) cases in synthetic gas–water–calcite systems. At 25 ∘C, changing the headspace-to-water ratio from 0.01 to 10 L kg−1 changed the gas fraction of a 10 mmol carbon input in 1 kg water from 0.0118 to 0.9214. A strong-base-to-carbon ratio of one reduced the 1 L-headspace gas fraction from 0.5436 to 0.00892. At that ratio, increasing calcium availability could raise both mineral storage and residual gas expression. A non-limiting CO2 reservoir and a finite pressure-constrained bubble produced aqueous states indistinguishable at the reported precision under different carbon-budget constraints; the same finite inventory partitioned differently at fixed volume. Four selected phase classifications persisted across three databases. These results identify conditional limits of gas-only inventory inference, not corrections to published palaeofluxes. Application to dated travertines additionally requires water throughput, source attribution, preservation and chronology. The calculations provide reproducible equilibrium benchmarks and a framework for identifying missing constraints before phase-selective observations are combined into Quaternary carbon budgets.
Channel erosion and sediment entrainment amplify rainstorm-triggered debris flows, but their interaction with topographic constraints remains poorly quantified. To reveal the controlling mechanism of erosion amplification on the disaster-forming process of rainstorm-type debris flows, using the 2016 Zhangba Xiaosha River event in Yunnan, China, we reconstructed debris-flow motion, erosion, and deposition with RAMMS::DEBRISFLOW. Five bed-erosion scenarios (0, 0.25, 0.50, 0.75 and 1.0 m) were used to assess changes in deposit thickness, runout, velocity, impact pressure, and volume amplification. The 1.0 m baseline scenario successfully reproduced the observed path, depositional extent, and representative deposit thickness. Increasing the equivalent erosion depth from 0 to 1.0 m increased the total debris-flow volume from 2.0 × 104 to 4.27 × 104 m3, yielding an amplification factor of 2.14; without erosion, maximum runout was 44.2% shorter. Along-channel erosion supply increases the mass, flow depth and momentum of the moving mass, forming an amplification chain of “sediment supply−scale amplification−momentum maintenance−frontal propagation”. Feedback may exist between actual erosion intensity, flow velocity and flow depth, but the equivalent erosion depth in RAMMS scenarios in this study is a predefined parameter. Topography exerted reach-specific controls: steep upstream channels promoted initiation and acceleration, the middle reach dominated erosional bulking, and the wider, gentler downstream reach enhanced dissipation and deposition. Within the erosion scenarios of 0.75–1.0 m set in this study, when the equivalent erosion depth increased further, the newly entrained sediment mainly increased deposit thickness and inundation extent, while the increment of maximum runout distance was limited. The event disaster scale resulted from coupled erosion-induced amplification and longitudinal topographic constraints. Hazard assessments should integrate initial initiation volume, erodible channel sediment, and local reach-scale topography.
