Charcoal Layers Research Articles

Flame retardant polyvinyl alcohol film with self‐releasing carbon dioxide and ammonia from phytic acid and urea

AbstractThis paper utilizes the reaction of phytic acid (PA) and urea (UM) in polyvinyl alcohol (PVA) solution to synthesize flame retardant gasses (CO2, NH3) for the preparation of PVA composite films containing flame retardant microbubbles. The flame retardancy of PVA composite films was assessed using methods including limiting oxygen index (LOI), vertical burning (UL 94), and cone calorimetry. The results indicated an increase in the LOI of the PVA composite film containing flame retardant microfoam from 20% to 30% compared with the pure PVA film, and that UL 94 reached VTM‐0. Furthermore, its peak exothermic rate and total exothermic amount were reduced by 36.25% and 38.92%, respectively, compared with the pure PVA film. The investigation of the flame‐retardant mechanism employed thermogravimetric‐infrared (TG‐IR), scanning electron microscopy (SEM), Raman spectroscopy, and infrared spectroscopy. The results demonstrate that the CO2 and NH3 flame retardant microbubbles within the composite film render it less ignitable at the initial stage, and that the internal UM of the composite film continues to decompose, releasing CO2 and NH3 upon heating. In addition, the acidic substances decomposed by PA during combustion promote the dehydration, cross‐linking, and cyclization of PVA, generating chemical structures such as POC, POP, and PO4 with enhanced thermal stability. This encourages the formation of a continuous, dense charcoal layer and impedes the transfer of oxygen and heat into the interior.

The Effect of Expanded Vermiculite on the Fire Resistance of Waterborne Acrylic Coatings.

Due to their ability to prevent or slow the spread of fires, fire-retardant coatings are utilized as the main means of fire protection for steel structures, combining easy application and high economic efficiency. This study investigates the effects of the particle size and dosage of expanded vermiculite (EV) on the fire resistance and application performance of coatings. Ammonium polyphosphate, melamine, and pentaerythritol were used as intumescent fire-retardant systems, along with waterborne hydroxyl-modified acrylic resins as the film-forming substances. The properties of fire resistance coatings were tested via scanning electron microscope (SEM), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and cone calorimetry. The excellent fire performance of the coatings with 3 wt.% 300-mesh EV was proven, exhibiting a relative expansion of 30.43 times. Moreover, the surface structure of the charcoal layer was dense. The total smoke production (TSP) and smoke concentration (TSR) were only 0.18 m2 and 0.25 m2/m2.

Flame-Retardant Coating on Wood Surface by Natural Biomass Polyelectrolyte via a Layer-by-Layer Self-Assembly Approach

In this study, environmentally friendly and low-cost biomass materials were selected as wood flame retardants. Three polyelectrolyte flame-retardant coatings made from chitosan (CS), tea polyphenols (TP), soybean isolate protein (SPI), and banana peel powder (BBP) were constructed on wood surfaces by layer-by-layer (LBL) self-assembly. The results of SEM-EDS and FT-IR analyses confirmed the successful deposition of CS-TP, CS-SPI, and CS-BPP on the wood surface, and the content of N element increased. The TG results showed that the initial decomposition temperature and the maximum thermal decomposition temperature of the coated wood specimens decreased, while the char residue increased significantly. This is due to the earlier pyrolysis of CS-TP, CS-SPI, and CS-BBP. This shows that the three polyelectrolyte flame-retardant coatings can improve the thermal stability of wood. The combustion behavior of the wood specimen was observed by exposure to combustion; the coated wood could self-extinguish within a certain period of time after ignition, and the flame-retardant performance was improved to a certain extent. SEM and EDS characterization analyses of the carbon residue after combustion showed that the coated wood charcoal layer was denser, which could effectively block heat and combustible gas.

Microcapsule Modification Strategy Empowering Separator Multifunctionality to Enhance Safety of Lithium-Metal Batteries.

The uncontrollable growth of lithium dendrites and the flammability of electrolytes are the direct impediments to the commercial application of high-energy-density lithium metal batteries (LMBs). Herein, this study presents a novel approach that combines microencapsulation and electrospinning technologies to develop a multifunctional composite separator (P@AS) for improving the electrochemical performance and safety performance of LMBs. The P@AS separator forms a dense charcoal layer through the condensed-phase flame retardant mechanism causing the internal separator to suffocate from lack of oxygen. Furthermore, it incorporates a triple strategy promoting the uniform flow of lithium ions, facilitating the formation of a highly ion-conducting solid electrolyte interface (SEI), and encouraging flattened lithium deposition with active SiO2 seed points, considerably suppressing lithium dendrites growth. The high Coulombic efficiency of 95.27% is achieved in Li-Cu cells with additive-free carbonate electrolyte. Additionally, stable cycling performance is also maintained with a capacity retention rate of 93.56% after 300 cycles in LFP//Li cells. Importantly, utilizing P@AS separator delays the ignition of pouch batteries under continuous external heating by 138s, causing a remarkable reduction in peak heat release rate and total heat release by 23.85% and 27.61%, respectively, substantially improving the fire safety of LMBs.

Real-time monitoring of charcoal layer resistance for investigating the synergistic flame retardant mechanism of zinc oxide and intumescent flame retardants in SBS

Metal oxides as synergists of intumescent flame retardant (IFR) lead to an extremely complex formation process of intumescent char layers. The lack of means to detect the evolution of the char layer in real time makes it challenging to investigate the synergistic flame retardant mechanism between metal oxides and IFR. Herein, an innovative method of detecting real-time changes in the resistance of the char layer under flame ablation is used to investigate its changes in morphology, thus assisting in revealing the synergistic flame retardant mechanism of zinc oxide (ZnO) in IFR/SBS. ZnO showed a significant synergistic flame retardant effect with IFR without MEL and no synergistic effect with MEL-containing IFR. The analysis of the char layer structure revealed that ZnO played a role in promoting gas release and char layer formation and increasing the viscosity of the molten char layer regardless of the presence or absence of MEL.The difference in the morphology of the char layer could not reveal the experimental phenomenon that there is no synergistic flame retardant effect between ZnO and MEL-containing IFR. The analysis of the real-time resistance of the charcoal layer reveals that ZnO achieves its synergistic flame retardation with the MEL-free IFR by increasing the expansion of the charcoal layer at the initial stage of its formation. For MEL-containing IFR, 0.5% ZnO inhibits the rupture of the char layer by promoting its formation in the early stages of ablation, and 1% ZnO leads to the rupture of the char layer instead, due to the promotion of gas release. Excess ZnO (2%) caused pyrolysis gases to escape from the voids of the char layer rather than allowing it to expand. The analysis of the real-time resistance of the charcoal layer can help to accurately reveal the flame retardant mechanism.

Combined optically stimulated luminescence and radiocarbon dating of aeolian dunes in Arctic Sweden

AbstractMultiple parabolic sand dune fields formed in Arctic Sweden after the last deglaciation, facilitated by an abundance of loose glaciofluvial sediment, limited vegetation cover and strong winds. Following initial stabilisation, these dunes underwent repeated reworking after fire events, as evidenced by the presence of buried soils, charcoal layers and redeposited sands in the dune stratigraphy. These reworking events may be driven by wider climate forcing; however, to date, no chronological framework exists for this activity in Sweden. As such, here, we apply quartz optically stimulated luminescence (OSL) dating of Arctic Swedish sand dunes using two dunes at the sites of Vastakielinen and Jorggástat. Resultant double‐SAR (single aliquot regenerative dose) quartz OSL ages are in good agreement with independent ages provided by 14C dating of charcoal fragments recovered from charcoal layers within the dunes, and we conclude that the chosen protocol is generally well suited for dating aeolian reworking of dune sediments in Arctic Sweden. While feldspar contamination limits precise age assignment for initial dune movement, our results nonetheless suggest repeated and long‐lasting aeolian activity in Arctic Sweden throughout the Holocene and, although there are differences in detail, further suggest some general trends in terms of dune stability and reworking over Arctic Fennoscandia.

The Combustion and Mechanical Properties of Guanidine Phosphate-Boron Compound-Silica Sol Composite Flame Retardant on Wooden Structure Building Components

ABSTRACT In order to develop a kind of wood with excellent flame retardancy properties, guanidine phosphate, boron compounds and silica sol were used as the main materials to formulate flame retardant solutions with different mass fractions, and to study the fire performance of wood structural building components after impregnation treatment with different flame retardant. The results showed that the LOI values of GPBS-4 and GPBS-5 increased by 82.22% and 97.78%, respectively, compared with that of the natural wood, and the residual charcoal rate of the wood was enhanced by 14.26% and 10.29% at 700°C, indicating that the composite flame retardants have high thermal stability. The results of cone calorimeter test showed that GPBS-4 had the most significant reduction of pHRR1, pHRR2 and THR, which were reduced by 43.01%, 41.06% and 36.97%, respectively, compared with the natural wood. The macroscopic morphology of the charcoal layer showed that the integrity of the charcoal layer of GPBS-4 was better, and the R-value of residual charcoal of GPBS-4 was reduced by 47.92% compared with that of the natural wood obtained by Raman spectroscopy, which indicated that the composite flame retardant effectively promoted the conversion of amorphous carbon into graphite structure, and facilitated charcoal formation in wood. In addition, the addition of silica sol in the flame retardant improved the effect on the mechanical properties of wood.

Effect of microencapsulation flame retardant on flame retardancy and mechanical properties of rigid polyurethane foams

AbstractA microencapsulated flame retardant PMDOPO was synthesized by solution blending method using EGDMA as initiator and AIBN as cross‐linking agent. Rigid polyurethane foams were prepared in a one‐step process. PMDOPO was incorporated into the foams by blending with polycarbonate diols (PCDL) and foaming additives. The results of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) showed that PMDOPO was well formed and uniformly dispersed in the foam. The pore size and density of the foams first increased and then decreased with the addition of PMDOPO. X‐ray photoelectron spectroscopy (XPS), vertical combustion test, and thermogravimetric analysis (TGA) showed that the PMDOPO content was directly proportional to the flame retardancy and the thermal stability. The major weight loss shifted to higher temperature intervals. The amount of residual char of RPUF/PMDOPO‐25 was enhanced 50 times to 10.63% compared to pure RPUF. In addition, SEM and Raman analyses of the combustion residual char revealed that a phosphorus‐containing char layer was formed during thermal degradation. The dense charcoal layer helps to insulate heat and suppress combustion. The universal testing machine showed that RPUF with 15 wt% content had the best compression resistance, with an enhancement of 1.8 MPa over pure RPUF.

Enhanced machine learning for nanomaterial identification of photo thermal hydrogen production

Instead of using temperature via an outside source, using energy created inside is the most effective method to improve the efficiency of catalysis. In this research, a novel hollowed TiO2 photothermal nano catalyst (referred to as RuO2/TiO2/Pt/Carbon) for enzymatic production of hydrogen under ultraviolet irradiation is used. It resembles a hedgehog and contains regionally dispersed Pta and RuO2 double co-catalysts. The ultraviolet (UV) thermos kinetic efficacy of the converters that were made was evaluated according to architectural characteristics and the heat influence of the carbon-based surface. There are several inherent benefits for photocatalysis with heterogeneity exist in multi-layered hollowed hetero structures having extremely thin two-dimensional (2D) nanosheet subunits of the including improved sunlight gathering, accelerated separation of charged particles and disposal, and accelerated interface oxidation reactions. The sandwich-like nanotechnology of the charcoal layer, silver tiny particles, and TiO2 surface effectively supports and protects Pt Micro particle against the accumulation and breaking down of Platinum sites that are active. Moreover, the electricity production of the reaction involving hydrogen evolution is nonetheless in its infancy, and there is tonnes of untapped potential for the use of Machine Learning (ML). The following perspective focuses on new developments in the detection of outstanding performance Hydrogen Evolution Reaction (HER) catalysts using Artificial Intelligence (AI) in an effort to stimulate more broad proposals for research. In the course of the research, an Artificial Neural Network (ANN) strategy was created and validated in order to forecast the results of the hydrogen assessment. The analysis of the dataset's test results demonstrates that the ANN technique can reliably and accurately estimate the generation of hydrogen.

Achieving superior fire safety for TPU 3D‐printed workpiece with EP/PBz/PDMS coating

AbstractTo reduce the possibility of the TPU 3D‐printed workpiece causing a fire, a flame‐retardant coating containing phosphorus, nitrogen, silicon, and benzene rings was fabricated on the TPU workpiece surface. When the MSDS content in the coating is 30 phr, the coated TPU composites LOL reached 29.5%, achieved V‐0 rating at the UL‐94 test and its peak heat release rate was reduced by 71.3% in the cone calorimeter test. When the MSDS content was increased to 20 phr, a continuous char layer was observed. Moreover, the EP/PBz/PDMS coating improved the thermal stability and tensile strength of TPU 3D‐printed workpiece. When the coating burns, it forms a dense charcoal layer, which isolates oxygen. The substrate wrapped by the charcoal layer undergoes a carbonization reaction when heated, preventing the substrate from burning further, resulting in improved flame retardancy, smoke suppression and dripping resistance of TPU.

Structure-property relationship of carbonized needlepunched nonwovens for electromagnetic interference shielding and ohmic heating applications

The structure-property relationship of acrylic and Kevlar fibre derived activated carbon fabrics was investigated for electromagnetic interference shielding and joule heating applications. The single stage carbonization and physical activation of acrylic and Kevlar needlepunched nonwoven fabric was carried out under the modified atmosphere of charcoal layer and nitrogen gas to have gradual reaction with atmospheric air. The effect of 800 °C, 900 °C and 1000 °C carbonization temperature on structural and functional properties was studied. The acrylic-derived activated carbon fabric was found to provide higher carbon yield, less dusting tendency, better mechanical and electrical properties; however poor flexibility and shrinkage properties as compared to Kevlar derived activated carbon fabrics. The formation of more micropores, higher graphitic structure, higher degree of crystallinity, and large surface area was observed in case of both the activated carbon fabrics with rise in carbonization temperature. Furthermore, the activated carbon fabrics derived at 1000 °C exhibited greater electromagnetic interference shielding in high as well as low frequency regions. Lastly, the ohmic heating of carbonized Kevlar fabric showed rapid heating, high electric heating efficiency and faster cooling performance but at increased voltage of 5 V than 3 V of carbonized acrylic fabric.

Architecture and function of salt-producing kilns from the 8th to 18th century in the coastal Sundarbans mangrove forest, Central Ganges-Brahmaputra Delta, Bangladesh

Subsidence along the central coast of the Ganges-Brahmaputra Delta and a subsequent rapid burial by mangrove mud have preserved a hundred earthen kilns at 11 localities, exposed due to recent coastal erosion. The associated pottery indicates that the kilns were used for salt crystallization in brine pots mounted on perforated hotplates. Four kiln varieties were found at successive elevations. The kiln chamber walls and the basal charcoal layers were dated using thermoluminescence and radiocarbon dating respectively. The oldest kilns with a round outline, found at the lowest elevations, were operating in the early 8th to middle 9th century. Oval-shaped kilns, found at a 1-m higher elevation, were used from the mid-9th to early 10th century. After a 600-year long period without documented kilns, rectangular kilns with a lateral slot were built again at a 1-m higher land surface in the 16th and 17th century. The youngest kiln type consists of rectangular twin chambers dating from the late 16th to mid-18th century and occurs at 1.5 m below the present sediment surface. Architecture and functioning of these rectangular kilns are reconstructed, showing a multi-step procedure. This technique had been improved in the 19th century when pyramidal kilns were described in historic records.

Evidence for the repeated occurrence of wildfires in an upper Pliocene lignite deposit from Yunnan, SW China

Charcoal remains and bulk lignites collected from the late Pliocene Jinsuo Basin in Yunnan, southwestern China, have been studied to reveal changes in the wildfire regime related to changes of the palaeoenvironment, palaeoclimate, and paleobotany. Different types of wildfire occurred in this paleomire with a predominance of low-temperature surface fires, as indicated by mean inertinite reflectance (Ro) values ranging from 1% to 2% in most samples. High-temperature fires are less recorded and occurred more frequently in dark layers compared with pale layers and charcoal layers, as deduced from the elevated proportion of high Ro values (>3%) produced by crown fires or high-temperature surface fires. Wildfire distribution in pale and dark layers was probably influenced by, changes of both plant community and of the depositional environment during their formation. Charcoal layers represent in situ surface and ground fires, whereas pale and dark layers probably record both in situ and remote fire events inside and/or around the basin. PAH were detected in all samples throughout the whole lignite seam, indicating that burning temperatures were low (<400 °C) in most cases in the peatland. Evidence of pre-charring decay observed in some macro-charcoal fragments and pyrogenic inertinite, along with the relatively high content of perylene, shows that decaying wood materials could be a part of the source fuel for the combustion during ground or surface fires. The occurrence and spread of wildfires in the basin during the formation of pale layers probably owe to the drought conditions driven by climate, whereas seasonality of precipitation and temperature was probably the major factor for the occurrence of wildfires recorded from dark layers. The distribution of wildfires within the profile may be relate to climate changes during the mid-Piacenzian.

Physical and foundry propertiesof Cu-Sn-Al system alloys

Tin-aluminum bronze containing Sn - up to 6.73% and Al - up to 7.53% (by weight) physical and casting properties determination. Methodology. Melting has been carried out in graphitecrucible in induction furnace under charcoal layer. Alloys liquidus and solidus temperatures have been investigated by thermography results of solidifying melt. Free (С) and absolutely difficult (АЗ) linear shrinkage values and alloy transition temperature from plastic to elastic state during cooling in mold have been studied by conventional methods. Bronzes fluidity has been estimated by the spiral sample filled channel length according to GOST 16438. Bronze BrO3A3 tendency to burn and to hot and cold cracks formation has been evaluated by samples surface visual examination results. Cast bronze specific density has been determined by calculation. Studied alloys mechanical properties have been calculated based on corresponding samples tests results at their impact bending at room temperature in accordance with actual standards. Alloys chemical composition control has been carried out on precision analyzer EXPERT 4L on specimens cut from club-shaped samples. Microstructural studies have been performed on metallographic microscopic samples prepared by standard methods on optical microscope Neophot-21. Approximation reliability value and corresponding dependences have been built using EXEL computer program. Results.According to qualitative and quantitative indicators and system Cu-Sn-Al bronzes with Sn content up to 6.73% and Al content up to 7.53% physical and foundry properties assessments, it has been determined that among possible tin and aluminum content in Cu-Sn- Al the most promising is bronze with 3...4% (by weight) of these alloying components each. Originality.For the first time number of physical and foundry properties of Cu-Sn-Al system bronze (with Sn content up to 6.73% and Al up to 7.53%) have been determined. It has been first established that such bronzes linear shrinkage, transition temperature from plastic to elastic state during cooling after solidifying and impact bending value at normal temperature depend on their structure, i.e. phase composition determined by its alloying elements content in bronze. Practical value.According to studies of physical and foundry properties results, bronze BrO3A3 has been recommended to be used as casting material

Mixed Characteristics of Activated Charcoal Ori Bamboo and Red Ginger as Air Purifier on Food Cabinets

Most of the community while preservation of food using refrigeration machines and chemicals, which less attention to hygiene. The storage space made of wood, glass or plastic where are almost airtight except the refrigerators which have poor air circulation and it cause of cross-contamination and also triggers bacteria growth, virus and fungi that cause decay and also disease source. These problems encourage the researchers to make a hygienic food storage space by consider the air circulation which is given an air purifier natural ingredients combinations that absorb pollutants, heavy metals, and anti-microbials. The air purifier ingredients which expected are original bamboo charcoal active, and red ginger. To make the air purifier can work effectively, a certain balanced composition is needed. The research method used is an experimental method where food ingredients are stored in a space where the air circulation is coated with a particle layer of original bamboo charcoal activate and red ginger rhizome with different compositions. The material used are mixture of charcoal and ginger rhizome by making an air purifier derived from activated charcoal from ori bamboo waste at a certain percentage of charcoal maturity. After that the product will be tested in food storage space with tofu for the food sample. In this research, the composition combination of ori bamboo charcoal active with red ginger extract was 4:0, 3:1, 2:2, 1;3, 0:4 where the ori bamboo charcoal active was used with a maturity percentage of 50%, 75%, 100 %. From the results of the research, it was found that the samples stored without using the filter grew with microbes after the second day, the samples that were filtered with the composition of activated charcoal only grew microbes on the third day and there was a change in the shape of the filter, namely the aqueous filter. Samples with a composition of activated charcoal with varying maturity and ginger extract began to grow with microbes after the fourth day. The best filter results using 100% mature activated charcoal with a composition of activated charcoal and ginger extract, which is 2:2. Microbes that can still grow in that composition are Bacillus substilis but in small quantities and no viruses or other microbes are found.

Activated Carbon Derived from Carbonization of Kevlar Waste Materials: A Novel Single Stage Method.

The augmented demands of textile materials over time have brought challenges in the disposal of substantial volumes of waste generated during the processing and end of life of such materials. Taking into consideration environmental safety due to discarding of textile waste, it becomes critical to recuperate useful products from such waste for economic reasons. The present work deals with the preparation of porous and electrically conductive activated carbon fabric by a novel single stage method of simultaneous carbonization and physical activation of Kevlar feedstock material procured from local industries, for effective electromagnetic (EM) shielding applications. The Kevlar fabric waste was directly carbonized under a layer of charcoal without any intermediate stabilization step at 800 °C, 1000 °C, and 1200 °C, with a heating rate of 300 °C/h and without any holding time. The physical and morphological properties of the activated carbon, influenced by carbonization process parameters, were characterized from EDX, X-ray diffraction, SEM analysis, and BET analysis. Furthermore, the electrical conductivity was analyzed. Finally, the potential application of the activated material for EM shielding effectiveness was analyzed at low (below 1.5 GHz) and high (2.45 GHz) frequencies. The phenomena of multiple internal reflections and absorption of electromagnetic radiations was found dominant in the case of activated carbon fabric produced at higher carbonization temperatures.

Latent Heat Flux (Evapotranspiration) in Summer Season on Rooftop Greening Soil with Bamboo Charcoal Sublayer at a Building in West Japan

The effect of a thin and light greening system with bamboo charcoal layer for water retention on heat fluxes, in particular latent heat flux (evapotranspiration rate), under no irrigation condition, on the rooftop of a building in Higashi-Hiroshima, West Japan, was investigated. In April 2019, lawn seeds (Zoysia tenuifolia) were sown which were germinated, reached a height of 70 mm by May when 100% of the vegetation area was covered. The air temperature and humidity at two different heights (0.3 m and 1.8 m) above greening soil surface, latent, and sensible heat fluxes were estimated. Bowen ratio was employed to collect the data on surface heat balance and soil water content during the summer season (June to September) in 2019 on the rooftop of a building in Higashi-Hiroshima, West Japan. The latent heat during daytime for a week without rainfall in each month was compared with the evapotranspiration rate. Owning to the vegetation development, the ground heat flux on greening soil surface decreased from -400 W/m2 to -200 W/m2 (flux from air to soil) during sunny daytime in July, and it was less than -100 W/m2 in August, although net radiation was maintained around 800 W/m2 over the season except in September. The monthly net radiation flux for an entire day (daytime and nighttime) ranged between 55 and 125 W/m2 (average: 95 W/m2) for the summer season of which 32-66% (average: 48%) was occupied by latent heat. Evapotranspiration from greening soil ranged between 1.24 and 1.82 mm/day, averaged at 1.51 mm/day throughout the season, which corresponded to about 26% of total rainfall over the season ( r 2 = 0.88 , p &lt; 0.01 ; S . E = 0.06 ) between the estimated and measured values. These observations suggested that the thin and bamboo coal light soil layer greening system, even without constant irrigation, could maintain the development of lawn grass and transformed more than half of net radiation to latent heat, i.e., evapotranspiration, insulating most ground heat in midsummer, which may be mostly due to bamboo charcoal sublayer.

High-resolution records of anthropogenic activity and geohazards from the reservoir of Sun Moon Lake, Central Taiwan

Sun Moon Lake is the first dam reservoir constructed in Taiwan with the capability of generating hydroelectricity satisfying the whole Taiwan need during the Japanese colonial period since 1934 CE. Now, the Sun Moon Lake is one of the biggest hydropower stations in Taiwan and has become an important touring area. During World War II (1944–1945 CE), the hydroelectric power plant at Sun Moon Lake was bombed by the U.S. air force, which caused severe damage to the dam structure. More recently, the dam structure was also damaged during the 1999 CE Chi-Chi earthquake whose epicenter is nearby in the Nantou County. A suite of cores were taken from both Sun Lake and Moon Lake, and two selected cores, Sun 2–1 and SM 16 4–3, from Sun Lake were detailed studied with multiple analyses, including X-ray imaging, magnetic susceptibility, visible spectrophotometry, X-ray fluorescence (XRF) scanning, and mineral analysis. We discovered that the increase of Ca content in the sediments not only clearly indicates when the dam was constructed at Sun Moon Lake but also records evidence of structure repairs after both the World War II bombing and the Chi-Chi earthquake. Additionally, the yellow turbidite, X-ray image, and low-Ca signals in Core Sun 2–1 strongly correlate to the typhoon events that caused severe floods in the watershed of Zhuoshui River. The turbidite layers caused by the 1963 Gloria Typhoon are also characterized by conspicuous high peak of Fe/Mn in both cores. This study shows that XRF scanning results are useful for recognition of human activity and for high precipitation event correlation. Moreover, the appearance of charcoal layers shows evidence of forest burning and slash-and-burn activities by humans during the past 4,000 years back to the Middle Neolithic Age.

Fiery rituals among the Alanian population of the Saltov culture of the Seversky Donets Basin (based on materials from catacomb cemeteries)

One of the typical features of the funeral rite of the Alanian population of the Saltov culture is the sprinkling of the burial chamber floor with a layer of charcoal. Paired (male + female) burials on coal bedding S. A. Pletneva considered as burials of couples in which coal was a symbol of “posthumous marriage”. The presence of coal bedding in solitary burials in the catacombs Nos. 6, 9, 11, 13, 17 of Rubizhan and the catacombs Nos. 1, 10 of the Staro-Saltov burial grounds allows us to offer a different interpretation of this feature of the Alanian funeral rite. At these cemeteries, the dominant type of burial structure was the catacombs with a longitudinal chamber in relation to the dromos, which were used by the Sarmatian-Alans often for one-time rather than family burials. Thus, taking into account ethnographic materials on Ossetians, it can be suggested that the initial sprinkling of charcoal on the floor of the burial chamber was associated with the rite of endowing the dead person with a “part of the family fire”, which was to ensure the unity of the dead people with their living relatives. In this context, the sprinkling of charcoal from the family hearth on the floor of the burial chamber should be considered as a desire to provide the deceased with the necessary heat and light, and thus turn the grave into a full-fledged otherworldly home, which, if necessary, could accept new deceased relatives. This assumption is confirmed by paired and collective burials at the Upper-Saltov burial ground, in which coal bedding was made only under one of the people buried in the chamber. At the same time, bodies of people were laid on the coal bedding, regardless of their gender (male, female) and age (children, adults). The use of charcoal to dry the chamber floor in adverse weather conditions before placing the bodies of a deceased person cannot be excluded.

Soils in Karst Sinkholes Record the Holocene History of Local Forest Fires at the North of European Russia

Despite the abundance of charcoal material entrapped in soils, they remain relatively less studied pyrogenic archives in comparison to the sedimentary paleofire records (e.g., lacustrine and peat deposits), and that is especially the case in most of Russia’s territory. We report here on the deep soil archives of the Holocene forest fires from the Pinega District of the Arkhangelsk region (64.747° N, 43.387° E). Series of buried soil profiles separated by charcoal layers and clusters were revealed in specific geomorphological traps represented by the active and paleokarst subsidence sinkholes on sulfate rocks overlaid by glacial and fluvial deposits. We combine the study of soil morphology and stratigraphy with a set of radiocarbon data on charcoal and soil organic matter, as well as the anthracomass analysis, to extract a set of paleoenvironmental data. A total of 45 radiocarbon dates were obtained for the macrocharcoal material and the soil organic matter. The maximum temporal “depth” of archives estimated from the radiocarbon dating of macrocharcoal reached 10,260 ± 35 cal yr BP. Soil formation with Podzols established at the inter-pyrogenic stages repeatedly reproduced within the period of ten thousand years, while the dominant tree species was Pinus sp. According to the macrocharcoal data, the intervals between fires have shortened in the last thousand years. Dendrochronological estimates suggest the occurrence of fires in almost every decade of the 20th and early 21st centuries. This is the first study of the millennia-scale soil record of forest fires in this particular region of Russia.