Thermally activated palygorskite and sepiolite clays are commonly used for the bleaching of edible oils and fats. However, their bleaching capacity can vary depending on physicochemical clay characteristics. The present study focused on the impact of thermally treated palygorskite and palygorskite-smectite clays on bleaching performance and showed a correlation between bleaching performance and the physicochemical characteristics of the clays. The mineralogical and chemical composition, along with certain physicochemical characteristics of thermally treated (heated at 300°C) palygorskite and palygorskite-smectite clays, were assessed for their effect on bleaching performance. The samples were collected from exploratory boreholes from four currently exploited clay deposits, namely Knidi, Pilori, Harami, and Velanida of the Upper Pliocene-Lower Pleistocene Ventzia Basin, west Macedonia, Greece. Palygorskite was formed diagenetically from smectite precursors of lateritic origin and deposited in a fluvial-palustrine environment. Clay minerals were characterized by X-ray diffraction (XRD), near-infrared spectroscopy (NIR), inductively coupled plasma optical emission spectrometry (ICP-OES) analysis, and gas porosimetry. The bleaching ability of the samples was evaluated by measuring the absorption of visible light through standard bleached rapeseed oil. Results revealed that the bleaching performance was superior in mixed palygorskite-smectite clays and was directly proportional to the palygorskite content and to both the apparent bulk density and external surface area of the clays. By contrast, bleaching ability was inversely proportional to the amount of non-clay minerals, but independent of the small variance in Al, Fe, and Mg contents of the clays or the octahedral composition of palygorskite. The presence of smectite in smaller amounts promoted to a small extent the efficiency of the palygorskite-rich clays from the Ventzia Basin.

Radiocarbon (14C) measurements on dissolved inorganic carbon (DIC) are a powerful tool to trace water masses and carbon cycling in the ocean. Existing methodologies to determine the 14C content of seawater DIC requires large volumes of sample (usually >100 mL) and specialized graphitization techniques to achieve the accuracy and precision needed for meaningful data interpretation. The advancement of the CO2 gas ionization accelerator mass spectrometry (AMS) technique today allows routine 14C measurements on small samples (<100 µgC) and may thus permit reducing the sample volumes needed to determine 14C content of seawater DIC to ∼2 mL. The proposed method utilizes the carbonate handling system (CHS), gas interface system (GIS) and MICADAS AMS, and provides good accuracy but reduced precision compared to established methods. Good accuracy is shown by comparing results for a marine in-house DIC standard and a DIC seawater profile from Antarctica between the proposed CHS-GIS-MICADAS approach and reference measurements conducted on the same material at established laboratories (ETH and NOSAMS). Further, two sedimentary porewater profiles from a fjord system in Svalbard are presented. Despite good agreement, the precision of the CHS-GIS-MICADAS approach is reduced, potentially limiting possible interpretations on seawater DIC. Nonetheless, the reduction of sample volumes proves particularly helpful to analyze porewater DIC from sediment cores, where sample material is notoriously limited, reduces the required amounts of toxic HgCl2 and simplifies expedition logistics.

Mass extinctions are natural experiments on the short- and long-term consequences of pushing biotas past breaking points, often with lasting effects on the structure and function of biodiversity. General properties of mass extinctions—exceptionally severe, taxonomically broad, global losses of taxa—are starting to come into focus through comparisons among dimensions of biodiversity, including morphological, functional, and phylogenetic diversity. Notably, functional diversity tends to persist despite severe losses of taxonomic diversity, whereas taxic and morphological losses may or may not be coupled. One of the biggest challenges in synthesizing and extracting general consequences of these events has been that they are often driven by multiple, interacting pressures, and the taxa and their traits vary among events, making it difficult to link single stressors to specific traits. Ongoing improvements in the taxonomic and stratigraphic resolution of these events for multiple clades will sharpen tests for selectivity and help to isolate hitchhiking effects, whereby organismal traits are carried by differential survival or extinction of taxa owing to other organismal or higher-level attributes, such as geographic-range size. Direct comparative analyses across multiple extinction events will also clarify the impacts of particular drivers on taxa, functional traits, and morphologies. It is not just the extinction filter that deserves attention, as the longer-term impact of extinctions derives in part from their ensuing rebounds. More work is needed to uncover the biotic and abiotic circumstances that spur some clades into re-diversification while relegating others to marginal shares of biodiversity. Combined insights from mass extinction filters and their rebounds bring a macroevolutionary view to approaching the biodiversity crisis in the Anthropocene, helping to pinpoint the clades, functional groups, and morphologies most vulnerable to extinction and failed rebounds.

Observation of thin sections of the WAIS (West Antarctic Ice Sheet) Divide ice core in cross-polarized light reveals a wealth of microstructures and textural characteristics indicative of strain and recovery in an anisotropic crystalline substance undergoing high-temperature plastic deformation. The appearance of abundant subgrain domains—relatively strain-free regions inside crystals (grains) surrounded by walls of dislocations across which small structural orientation changes occur—is particularly noticeable in the depth range associated with the brittle ice (∼650–1300 m). Here we describe a subgrain texture, not previously reported in ice, that resembles chessboard-pattern subgrains in β-quartz. This chessboard texture at WAIS Divide is strongly associated with the presence of bubbles. We hypothesize that chessboard-subgrain development may affect grain-size evolution, the fracture of ice cores recovered from the brittle ice zone and perhaps grain-boundary sliding as well.

Loess, a geologic record of dust, is an optimal archive for exploring paleoclimate and the paleo-dust path from source to sink. The dust path for the Songnen Plain, NE China, during the last glacial period has not been established. To address this, 63 surface sediment samples from the Northeast China Sandy Lands, i.e., Onqin Daga Sandy Land (OD), Horqin Sandy Land (HQ), Hulun Buir Sandy Land (HL), and Songnen Sandy Land (SN), and six samples from the last glacial loess in the Harbin area were collected for elemental geochemical analysis of the <10 μm fraction to quantitatively reconstruct the dust pathway using a frequentist model. The results show that these sandy lands have a distinct geochemical composition due to a control from markedly different provenances. The quantitative results indicate that the dust contribution of the southwestern SN to the Harbin loess is as high as 50.4–77.2%, followed by the OD and HQ (3.3–34.8%), the northwestern SN (0–36.8%), and the HL (0–8%). Notably, the dust contribution to the Harbin loess began to change considerably after ~46–41 ka BP, with a significant increase from 1.1% to 41.2% from the northwestern direction. Some ecological safety strategies are proposed to address dust pollution in the Harbin area.

A 350 14C yr discrepancy was found between dates on postcranial remains and mandibular teeth on what was thought to be the same individual from the Early Neolithic cemetery of Shamanka II, Lake Baikal. Stable nitrogen isotope results suggested a major shift in diet between childhood (when the teeth formed) and adulthood (represented by the postcrania), which could have resulted in different 14C ages through a freshwater reservoir effect. Subsequent additional dating on the mandible and postcranial elements, however, indicated that the mandible actually belonged to a different individual. More subtle reservoir effects can be seen on the sequentially forming teeth and mandible. The practice by prehistoric hunter-gatherers of Lake Baikal of re-opening graves and removing cranial elements has long been known, but this is the first evidence for the inclusion of a mandible from a separate individual, though whether it was intentional or incidental is uncertain. As well as providing new insights into mid-Holocene mortuary practices in the region, our findings raise a cautionary note for the examination of disturbed graves.

Passive microwave measurements of Arctic sea ice have been conducted over the last 50 years from space and during airborne, ship- and ground-based measurement campaigns. The different radiometric signatures of distinct surface types have led to satellite retrievals of, e.g., sea-ice concentration. In contrast, ground-based upward-viewing radiometers measure radiation emitted from the atmosphere and are used to retrieve atmospheric variables. Here, we present results from a ship-based radiometer setup with a mirror construction, which allows us to switch between atmospheric and surface measurements flexibly. This way, in summer 2022, surface observations in the Arctic marginal sea-ice zone could be performed from the research vessel Polarstern by two radiometers covering the frequency range from 22 to 243 GHz. At low frequencies, the brightness temperatures show clear signatures of different surface conditions. We estimate emissivities at 53∘ zenith angle from infrared-based skin temperatures. Predominantly vertically polarized 22–31 GHz emissivities are between 0.51 and 0.55 for open ocean and around 0.95 for sea ice. Predominantly horizontally polarized 243 GHz ocean emissivities are around 0.78 and ice surfaces exhibit a large variability from 0.67 to 0.82. Our results can improve the characterization of surface emissions in satellite retrieval algorithms.

Here we present the first high-resolution continuous palaeoecological study from Greece covering the Mesolithic–Neolithic transition at Limni Zazari, a small lake in western Macedonia. We study how interactions between vegetation and climate might have affected the introduction of agriculture to Europe ca. 8500 years ago. We found that mixed deciduous oak woodlands established around the lake once moisture availability began to increase at ~10,300 cal yr BP. Between 8600 and 8000 cal yr BP, climate change, causing drier conditions, led to the decline of the woodlands and the expansion of steppe and grassland vegetation. Concurrently, in agreement with the archaeological record, pollen indicative of arable and pastoral farming indicate the onset of Neolithic farming. After 8000 cal yr BP the forest composition changed, with a major expansion of pine forests and increases in disturbance-adapted trees like Ostrya and Fagus. This change might be linked to changes in moisture availability, but it is likely that land use also facilitated these shifts. We conclude that the introduction of Neolithic farming was advantaged by climate-induced vegetation changes. While the vegetation structure around Zazari was very sensitive to changes in moisture, early anthropogenic disturbances led to changes in the vegetation composition that are still important today.

Prehistoric humans seem to have preferred inhabiting small river basins, which were closer in distance to most settlements compared to larger rivers. The Holocene landscape evolution is considered to have played a pivotal role in shaping the spatiotemporal patterns of these settlements. In this study, we conducted comprehensive research on the relationship between landscape evolution and settlement distribution within the Huangshui River basin, which is a representative small river in Central China with numerous early settlements, including a prehistoric city known as the Wangjinglou site (WJL). Using geoarchaeological investigations, optically stimulated luminescence dating, pollen analysis, and grain-size analysis, we analyzed the characteristics of the Holocene environment. The results indicate the presence of two distinct geomorphic systems, namely the red clay hills and the river valley. The red clay hills, formed in the Neogene, represent remnants of the Songshan piedmont alluvial fan that was eroded by rivers. There are three grades of terraces within the river valley. T3 is a strath terrace and formed around 8.0 ka. Both T2 and T1 are fill terraces, which were developed around 4.0 ka and during the historical period, respectively. The sedimentary features and pollen analysis indicate the existence of an ancient lake-swamp on the platform during 11.0–9.0 ka. This waterbody gradually shrank during 9.0–8.0 ka, and ultimately disappeared after 8.0 ka. Since then, the development of large-scale areas of water ceased on the higher geomorphic units. River floods also cannot reach the top of these high geomorphic units, where numerous prehistoric settlements are located, including the Xia–Shang cities of the WJL site. Our research demonstrates that landscape stability supported the long-term and sustainable development of ancient cultures and facilitated the establishment of the WJL ancient cities in the region.

The new mineral tarutinoite, ideally Ag3Pb7Bi7S19, was found in a fragment of a drill core extracted at the 178.5 m level of borehole #4604 at the Tarutinskoe (Tarutino) copper-skarn deposit, Chelyabinsk Oblast, Southern Urals, Russia. It occurs as anhedral grains up to 0.10 × 0.05 mm intergrown with hessite and galena in magnetite and calcite. Tarutinoite is grey, opaque with metallic lustre, brittle tenacity and uneven fracture. No cleavage and parting are observed. The Vickers’ micro-indentation hardness (VHN, 25 g load) is 178 kg/mm2 (range 165–194, n = 4), corresponding to a Mohs’ hardness of 3.5–4, and calculated density is 7.180 g/cm3. In reflected light, tarutinoite is greyish-white, very weakly bireflectant and non-pleochroic. Under crossed polarisers the new mineral exhibits moderate anisotropy, in grey and dark grey tones with bluish tints. The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association are (Rmin/Rmax, %): 45.5/47.9 (470 nm), 43.5/45.0 (546 nm), 43.3/44.1 (589 nm) and 41.8/42.5 (650 nm). The chemical composition (wt.%, electron microprobe data, mean of 7 spot analyses) is Cu 0.30, Ag 8.33, Cd 0.04, Pb 37.12, Bi 37.52, S 15.15, Se 0.40, Te 0.66, total 99.52. The empirical formula calculated on the basis of 36 atoms per formula unit is (Ag3.01Cu0.18)Σ3.19(Pb6.98Cd0.01)Σ6.99Bi7.00(S18.42Se0.20Te0.20)Σ18.82. Tarutinoite is monoclinic, space group C2/m, with a = 13.5447(12), b = 4.1027(3), c = 32.481(4) Å, β = 96.433(9)°, V = 1793.6(3) Å3 and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 16.15 (48) (0 0 2), 3.407 (69) (1 1 –5), 3.328 (95) (2 0 –9), 3.042 (65) (2 0 –10), 2.941 (100) (3 1 2), 2.910 (55) (3 1 –4), 2.053 (44) (0 2 0). The crystal structure of tarutinoite was refined to R1 = 0.1349 for 2024 reflections with Fo > 4σ(Fo) and 84 refined parameters. The new mineral is the first 7,8L member of the lillianite homologous series. It is named after its type locality.

The study analyses in situ CO2 mole fraction, 14CO2, and fossil based excess CO2 mole fraction (Cfoss) data at Hegyhátsál (HUN) rural monitoring station (Central Europe) supplemented by passive monitoring of 14C content of tree-rings. Through the observed period (2014–2020) we focused on revealing trends in atmospheric CO2 and 14C levels, particularly during the year of the first COVID lockdown, in comparison to the preceding five years. In addition, monthly integrated samples of atmospheric CO2 and tree-rings from the six years were subjected to 14C analysis. The passive tree-ring measurements focuses on two major urban areas (Budapest and Debrecen) in Hungary, along with the rural monitoring site. Results show a steady increase in CO2 levels at HUN between 2014 and 2020. The calculated fossil based excess CO2 concentrations for the initial year of COVID are in good agreement with the previous five-year averages both at 115 m and 10 m elevations. These results also show seasonal variations of CO2 mole fractions, peaking in winter and decreasing in summer. Tree-ring results from Debrecen show a good alignment with the results of the atmospheric monitoring station, and it does not show a significant fossil contribution in the urban background area during the vegetation periods. Tree-ring results from Budapest show a stronger fossil contribution compared to the Debrecen ones. Our atmospheric CO2 results do not show a large decrease in fossil CO2 atmospheric contribution during the first lockdown. We found that the use of this passive CO2 monitoring technique can provide a valuable tool for investigating such differences.

This work reports the first data on the Variscan metamorphic evolution of the Marmarosh/Maramuresh massif in the Outer Eastern Carpathians. Geothermobarometry determinations coupled with U-Th-Pb dating of monazite, apatite, titanite and rutile were used to construct P-T-t paths and refine the geodynamic evolution of the pre-Alpine crystalline basement. These clockwise P-T-t paths evolve from 560–630 MPa and 515–535 °C to c. 900–1180 MPa in the north (Ukraine), while in the southern nappe (Romania), the P-T-t conditions evolve from 455–620 MPa and 545–555 °C, through to 670–745 MPa and 540–560 °C, to 910–965 MPa and 645–660 °C. The northernmost nappes were likely structurally lower relative to the southern nappes. Variscan progressive metamorphism related to nappe stacking climaxed at 350–340 Ma, as documented by U-Pb rutile and U-Th-Pb monazite dating.

In both regions, post-kinematic exhumation to 700–500 MPa, 550–630 °C MPa and then to the titanite stability field was dated at 317–327 Ma, using the U-Pb system on apatite and titanite. Subsequent Permian retrogression and exhumation was constrained to 280–290 Ma by U-Pb rutile and apatite and U-Th-Pb monazite dating. These data link the massif to the external zone of the Central European Variscides. We infer that all Variscan crystalline basement fragments in the Alps and Carpathians probably represent remnants of the same microcontinent, which was dismembered during Alpine orogenesis.

Two-dimensional (2D) views dominate the application of linear elastic fracture mechanics to problems in ice-shelf rift propagation, yet from the perspective of fracture mechanics, processes at the rift front are inherently three-dimensional (3D). 2D simplifications are nevertheless desirable for their efficiency and apparent compatibility with shallow-shelf approximation (SSA) ice flow models. Here, the implications of flattening the ice-shelf rift problem are investigated and a theoretical foundation is established to support using a plane stress approximation. In this way, we verify compatibility between 2D simplifications for rifts and for ice-shelf flow, which is a requirement for situations in which SSA-derived stresses are used to study rift propagation. Comparing the plane problem to a 3D counterpart, we show that the 2D results at rift tips are a good estimate for mean rift front stress conditions. Mode I (opening mode) stress intensity factors exhibit a depth-dependence that implies that rifts should be longer at the ice base than at sea level. Other minor 3D effects, which also involve Modes II and III, arise where the rift front intersects the upper and lower ice surfaces.

Iceland was one of the last places in Europe to be settled. It thus has a relatively short population history as it was completely depopulated until about 871. Harsh climatic conditions, periodic epidemics, and numerous natural disasters were not conducive to robust population growth on the island. This article traces the demographic transition of Iceland’s population from the initial settlement to the present. This is the transition from high to low birth and death rates as a population modernises. Iceland has an impressive literary and historical record-keeping tradition beginning with the Saga Age in the 900s. It also has long had a well-developed statistical system which allows the study of population trends much further back in time than many countries. The results show slow population growth for much of Iceland’s history with many episodes of steep population decline. A series of technological innovations in the 19th century allowed the country to modernise, the population to grow, and its demographic situation to improve. Iceland has completed the demographic transition, the population is growing, in part due to high immigration, and it has some of the best demographic indicators in the world. Despite these favourable trends, the country faces some demographic challenges.