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International audience; Weathering phenomena are ubiquitous in urban environments, where it is easy to observe severely degraded old buildings as a result of water penetration. Despite being an important part of any realistic city, this kind of phenomenon has received little attention from the Computer Graphics community compared to stains resulting from biological or flow effects on the building exteriors. In this paper, we present physically-inspired deep weathering effects, where the penetration of humidity (i.e., water particles) and its interaction with a building's internal structural elements result in large, visible degradation effects. Our implementation is based on a particle-based propagation model for humidity propagation, coupled with a spring-based interaction simulation that allows chemical interactions, like the formation of rust, to deform and destroy a building's inner structure. To illustrate our methodology, we show a collection of deep degradation effects applied to urban models involving the creation of rust or of ice within walls.

Article, 環境科学年報 45 : 13-16, (2023)

Microplastics are an emerging and persistent pollutant due to their threat to global ecological systems and human health. Recent studies showed that microplastics have infiltrated the remote Third Pole - the Tibetan Plateau. Here, we summarize the current evidence for microplastic pollution in the different environments (rivers/lakes, sediment, soil, ice/snow and atmosphere) of the Tibetan Plateau. We assess the spatial distribution, source, fate, and potential ecological effects of microplastics in this broad plateau. The integrated results show that microplastics were pervasive in biotic and abiotic components of the Tibetan Plateau, even at the global highest-altitude, Mt. Everest. Although the concentration of microplastics in the Tibetan Plateau was far below that found in the densely populated lowlands, it showed a higher concentration than that in the ocean system. Tourist populations are identified as a substantial source of anthropogenic plastic input rather than local residents due to the rapid development of the tourism industry. In the sparsely inhabited remote area of the Tibetan Plateau, long-range atmospheric transport facilitates allochthonous microplastic diffusion. Robust solar radiation in the Tibetan Plateau might enhanced production of secondary microplastics by weathering (UV-photooxidation) of abandoned plastic waste. A rough estimation showed that the microplastic export flux from melting glaciers was higher than that measured in most of the world's largest rivers, which affects local and downstream areas. Since the Tibetan Plateau is vital for Asian water supply and numerous endangered wildlife, the potential human and ecological risk of microplastics to these fragile ecosystems needs to be fully evaluated within the context of climate-change impacts.

This article presents a comprehensive vision of particularities and constraints of the Paja Formation in the Northern Andes of Colombia, supported by personal, institutional, and academic experiences, including a doctoral thesis in completion (geomorphology and risks research line). Such fine-grained marine rocks cause severe damage in diverse zones, with little spread, and are very unfavorable, especially within the Eastern Cordillera (departments of Santander and Cundinamarca), whose socio-environmental problems motivated a popular legal action in the municipality of Vélez due to the cracking and collapse of houses, damage to roads and landslides in the urban area, as well as flows, subsidence, and high hydrogeochemical dynamism or rare earths, although they also presented spontaneous ignition at the rural area. Understanding how these problems originate and interrelate is the main objective of the work. At the beginning, we include some brief definitions, terms, and key approaches to understand the consolidated geomaterials, location, and background of the problem; then, the results of meso–macro–micro studies, obtained by combining the field techniques and conventional instrumental laboratory analyses (tests on the chemistry of water and soil, description of samples with magnifying glasses, petrography with a polarized light microscope, micromorphology of regoliths–colluvions) of nanoscientists (emphasizing RXD-RXF, SEM, IR-Raman spectroscopy, TOC-TS) are presented. These characterizations and new knowledge must be socially and institutionally appropriated and applied in land use planning and risk management for the sustainability of challenging environments with the stratiforms of Lower Cretaceous rocks and associated Quaternary deposits in populated mountainous areas and contrasting intertropical hydroclimatological regimes, geologically active, so unstable and insecure.

Data on the mineralogy and geochemistry of rare earth elements (REE + Y) in water, suspended matter and stratified sediment cores from different parts of Lake Onego are presented. The study finds that the dissolved REE + Y in the water from different areas of Lake Onego have common features: (1) a maximum in the area of middle rare earth elements (MREE), (2) a distinct negative Ce anomaly and (3) a positive Eu anomaly. Comparison of the average concentration of elements in the stratified core of the bottom sediments and particulate matter (from the filters and sedimentation traps) from different parts of Lake Onego and the distribution of REE + Y do not reveal any significant differences. The trend of the REE + Y distribution for samples from the South Onego completely coincide the REE + Y distribution in siltstones and sandstones of the Russian Platform Scale Composite (RPSC). In the water area of Lake Onego from south to north, a well-defined trend of changes in REE + Y patterns relative to the RPSC is revealed, with depletion by heavy REE + Y and gradual enrichment by light rare earth elements (LREE). Geochemical and mineralogical data confirm our hypothesis of a significant reformatting of the catchment basin of the Onego Ice Lake in the Late Pleistocene. During the formation of the preglacial lake, a significant part of the catchment area was located south of Lake Onego and is mainly represented by Russian Platform sedimentary rocks. Due to the degradation of the Last Glacier from the Lake Onego depression and the nearby territories, the catchment area changed of its southern and south-eastern sections. Today the composition of the modern sedimentary matter entering Lake Onego is determined by mixing clusters from two geochemically contrasting feeding areas: loose sediments formed by the repeatedly re-deposited products of the weathering of the Fennoscandian Shield's crystalline rock massifs, including Phanerozoic sediments; and to a lesser extent the sediments of the sedimentary cover of the Russian Platform, except the bottom sediments of the South Onego, in which Phanerozoic sedimentary formations have completely predominated throughout the lake's development.

広島県東広島市の七ツ池では，排水時の池底で赤色風化した堆積物を観察できる。この池底堆積物の柱状試料を4 本採取し，各柱状試料について層相，pH，酸化還元電位測定，色彩測定，及び赤色部の詳細観察を行った。その結果，（1）風化層の多くは，砂層の上位に位置し，地下水面の変動帯に位置していること，（2）赤色化メカニズムのモデルについては，砂層の間隙水中での拡散供給のプロセスが適用できたが，無機的な酸化還元反応だけではなく，硫酸還元菌や鉄酸化細菌などの微生物の関与を考慮する必要があること，（3）色彩データのうち，彩度が化学的風化（鉄酸化物生成）の進行状況の指標として有用性があることが明らかとなった。また，これらの結果に基づいて七ツ池の堆積物の地学の学習素材としての可能性を考察した。, During drainage, reddish weathered sediments can be observed at the bottom of Nanatsu-ike Pond in Higashihiroshima City, Hiroshima Prefecture. Four columnar samples of this reservoir-bottom sediment were collected. Each columnar sample was subjected to facies, pH, redox potential measurement, color measurement, and detailed observation of the red part. The results showed the following: (1) most weathered layers were located above the sand layer and in the zone of groundwater-surface fluctuation; (2) for the model of the reddening mechanism, the process of diffusion-supply in the pore water of the sand layer could be applied, but it was necessary to consider the involvement of microorganisms such as sulfate-reducing bacteria and iron-oxidizing bacteria in addition to the inorganic redox reaction; and (3) among the color data, chroma was found to be a useful indicator of the progress of chemical weathering (iron oxide formation). Based on these results, the potential of the Nanatsu-ike Pond sediments for geoscience educational materials is discussed.

This research evaluates the behavior of plaster with a water-repellent additive when submitted to a natural aging process. Casting plaster and silane/siloxane-based water-repellent were used as materials. The water/plaster ratio was set at 0.7 and the contents of 0.2% and 0.4% of water-repellent were used, in relation to the plaster mass. Plaster pastes without water-repellent (reference) and containing mass water-repellent were evaluated at ‘zero’ age and after 30, 60, 90, 120, and 150 days of natural aging. After 150 days of natural aging, it was observed that the mechanical properties of the material (compressive strength and hardness) did not undergo significant variations and remained above the minimum required by a standard. The addition of water-repellent resulted in a considerable reduction in water absorption, demonstrating the water repellency capacity of the material, compared to the reference specimen.

Rocks and minerals buried in the earth’s surface usually undergo weathering processes and change color in the burying environment. A kind of yellow Chinese stamp stone named “Lumu stone”, which is buried in a yellowish weathering crust (yellowish soil), was selected to investigate its color changes in the weathering processes. In this study, the appearance features, mineral components, micromorphology, spectroscopy characteristics, and color causation of the “Lumu stone” were studied by using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), an electron probe microanalyzer (EPMA), a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS), and a UV-Visible (UV-Vis) spectrum. The “Lumu stone” usually exhibits a darker yellow outer layer and a lighter yellow core, suggesting that yellow color permeated into the stone from the surface to the core gradually and the color is secondary forming. The results from XRD and SEM show the studied samples are mainly composed of dickite and illite. The individual particles of the dickite and illite are about 2–5 μm, randomly distributing in the three-dimensional space and constituting voids among the particles. The acid pickling experiments using HCl coupled with KSCN confirmed that the mineral phases that caused the yellow color of the matrix are iron oxide and hydroxide. On the other hand, goethite and hematite were observed gathering in the yellow and brown-red cracks on the “Lumu stone” by SEM study. However, iron oxide and hydroxide in the matrix were difficult to observe and detect among the dickite and illite aggregates by SEM and XRD methods. It indicates that they may be nanoscale in size and very low in content. According to the calculation of the second derivative of Kubelka-Munk (K-M) transformed diffuse reflection spectroscopy (DRS) curves obtained from UV-Vis, the characteristic peaks of goethite and hematite were found in the yellow matrix, and their contributions to the color were confirmed. The concentrations of goethite and hematite were calculated to be 0.32 to 1.87 g/kg and 0.22 to 0.93 g/kg in the studied samples, respectively. In this study, a series of methods were employed to detect very low levels of goethite and hematite in the samples undergoing weathering processes. Additionally, nanoscale goethite and hematite were considered newly formed minerals when buried in the weathering processes and may gradually move into the voids among phyllosilicate particles. Therefore, they turned the “Lumu stone” yellow.

Understanding how sediment is produced, transported and weathered remains a key area of study within geomorphology. Much of this occurs in upland landscapes of interconnected hillslopes and fluvial systems where material is originally sourced from the bedrock underlying hillslopes and transported throughout the system. This conveyor belt like process combines the competing effects of erosion and weathering at the landscape scale. Erosion is required to separate bedrock and export it away allowing fresh material to subsequently be disintegrated. Weathering acts on these particles once in the soil column to transform parent material in to secondary weathering products. This gives a steady supply of secondary weathering products, often clay minerals, which provide a number of functions within the landscape. Namely the stabilisation and export of organic carbon from the hillslopes to deep oceanic sinks. However this stable flux is still poorly understood and quantified, particularly in terms of how it may vary with changing erosion rate. Constraining and exploring this relationship is therefore of prime interest in a rapidly changing world. This thesis is focused on the development of a new numerical model (LSDMxingModel) coupling a particle based geomorphological model with a reactive transport geochemical model in order to better understand these upland conveyor belts. Alongside this, existing field data and topographic analysis methods are used in order to test the model and see if the theoretical relationships can be observed at the landscape scale. To begin with I do this with a series of USA wide datasets encompassing erosion rate, soil pedon, climate, and elevation data and use topographic analysis techniques to link erosion rate with pedon data for the clay particle size fraction. Across five different landscapes in the continental USA I find three that this linkage can occur in (and two where it does not to demonstrate the results are not spurious). In them the clay particle size fraction has a negative correlation with erosion rate, expected since more erosion results in less time for parent material to breakdown in to clays within the soil. Combining this data allows the estimation for clay flux to be obtained in these landscapes for the first time and find that an optimum erosion rate exists to maximise clay flux. From this I move onto using the LSDMixingModel for further exploration of the effects of mixing and hillslope transience. Firstly I present the rationale and equations behind it followed by a series of analytical tests involving Cosmogenic Radionuclides (CRN). CRN are a common tool used to calculate erosion rate and provide a proxy for the amount of time spent within the soil column so are a useful proxy for the extent of weathering. I then present findings from a series of model runs exploring transient hillslope conditions before moving on to analysing three hillslopes with CRN soil data from the Feather River, California. I use DEM data and a new algorithm to help convert these hillslopes to the LSDMixingModel domain. I successfully apply the model to demonstrate the effects of transient conditions caused by a change in fluvial incision in both real and theoretical landscapes. Alongside this I show the effects of partial and full mixing on soil CRN concentrations and how they may have to be considered when calculating basinal erosion rates. Finally I incorporate the geochemical side of the LSDMixingModel (in the form of CrunchFlow) to model a series of theoretical scenarios to explore the potential effects of mixing, transience, and erosion on both simple and more complex parent mineralogy. I find that increasing soil mixing can have the effect of smearing or stalling the reaction front of primary Albite weathering into secondary Kaolinite. Likewise I confirm some of the theoretical ideas on optimum clay fluxes using a series of transient hillslope runs. Alongside this I attempt to isolate the effect of inheritance on the clay flux along with demonstrating that the clay fraction change propagate upslope from a base level change in a similar manner to the hillslope steepness and soil thickness. Finally I explore how erosion and mixing may affect the competing production of 2 types of clay mineral (Illite and Kaolinite) and how erosive conditions can keep the soil young enough for Illite to dominate the clay mineral fraction whereas otherwise it weathers out over time. This supports theoretical and field based findings on how the clay mineralogy might change with 2:1 clays (Illite) giving way to 1:1 clays (Kaolinite) over time.

Facial prostheses are created from special elastomers modified for their specific physical and mechanical properties; however, they also show two common major clinical problems: gradual discolouration of the prosthesis over time in service environment and deterioration of static, dynamic, and physical properties. As a result of external environmental factors, facial prostheses may become discoloured and discolour by changing colour from intrinsic and extrinsic colouring, and this is associated with the intrinsic colour stability of elastomers and colourants. Thus, in this in vitro study, a comparative evaluation of the effect of outdoor weathering on the colour stability of A-103 and A-2000 room-temperature vulcanised silicones used for maxillofacial prosthesis was conducted. To accomplish this study, a total of 80 samples were fabricated, 40 samples of each material were grouped as clear (20) and pigmented (20). These samples were mounted on wooden board and the assembly was placed on the roof of the dental school from October 2021 to March 2022. To maximise the amount of sunlight on the specimens, the exposure rack was set on five 68° angles from horizontal and also to prevent standing water. The specimens were left uncovered during exposure. The testing of samples was conducted with the help of a spectrophotometer. The colour values were recorded in the CIELAB colour system. It describes the three colour coordinates (colour values) x, y, and z in three new reference values of L, a, and b, aiding in numerically classifying colour differences. After 2, 4, and 6 months of weathering, testing was conducted using a spectrophotometer and the colour change (ΔE) was calculated. The A-103 RTV silicone group with pigmentation showed the maximum change in colour after six months of environmental conditioning. The data for colour difference within groups were analysed using a one-way ANOVA test. Tukey’s post hoc test assessed the pairwise mean comparison’s contribution to the overall significant difference. The nonpigmented A-2000 RTV silicone group showed the maximum change in colour after six months of environmental conditioning. After 2, 4, and 6 months of environmental conditioning, pigmented A-2000 RTV silicone showed better colour stability than A-103 RTV silicone. The patients requiring facial prosthesis do need to work on outdoor fields, and thus weathering will have deleterious effects on such prosthesis. Hence, the selection of appropriate silicone material with respect to the Al Jouf province region is crucial, which includes economic, durable, and colour stability.

L’altération des ossements face à l’exposition aux agents atmosphériques est aujourd’hui bien connue, mais il faut envisager que les os brûlés ne subissent pas les mêmes modifications puisque leurs propriétés physico-chimiques sont modifiées par la combustion. C’est dans la perspective de mieux appréhender ces réactions qu’une série d’expériences a été réalisée. Elles s’inscrivent dans un cadre plus large qui tend à mieux appréhender l’impact des agents taphonomiques sur les os brûlés afin d’estimer les distorsions qui existent entre le matériel osseux provenant de combustions expérimentales et le matériel fossile. Cinq séries expérimentales issues de combustions réalisées à partir d’humérus frais de bœuf ont été exposées pendant dix-huit mois aux agents atmosphériques, en contexte méditerranéen. Plusieurs critères ont été observés pour mettre en évidence l’impact de cette exposition sur les ossements brûlés : degré de fragmentation, perte de masse osseuse, altération des surfaces osseuses, influence du degré de combustion (carbonisé vs calciné) et du tissu osseux (spongieux vs compact) sur la conservation du matériel. Les résultats de cette expérimentation mettent en exergue une forte fragmentation du matériel (les os brûlés de petite dimension sont majoritaires), associée à une réduction de la masse osseuse. De plus, les os spongieux et calcinés ont une sensibilité accrue à l’action des agents atmosphériques, qui entraîne leur destruction. Ainsi, à terme, une conservation préférentielle de l’os compact carbonisé est attendue.

The alteration of bones following exposure to weathering is today well known, but it is possible that burned bones do not suffer the same type of changes since their physicochemical properties are modified by combustion. A series of experiments has been carried out with the aim of better understanding these reactions. These experiments form part of a more widespread attempt to better understand the impact of taphonomic agents on burned bones in order to estimate the distortions between bone material originating from experimental combustion and the fossil material.Five experimental series resulting from the combustion of fresh cow humeri were exposed for eighteen months to weathering in a Mediterranean context. Several criteria were observed in order to highlight the impact of this exposure on the burned bones: degree of fragmentation, loss of bone mass, alteration of bone surface, influence of the degree of combustion (carbonised vs charred) and of the bone tissue (spongy vs compact) on the preservation of the material. The results of these experiments mainly show a high fragmentation of the material (the small burned bones being in the majority), associated with a reduction in bone mass. In addition, spongy and charred bones have an increased sensitivity to the action of weathering, leading to their destruction. A preferential preservation of charred compact bone is thus expected.

International audience; During serpentinite rock weathering, Ni is concentrated in the regolith owing to residual and secondary enrichment, forming a Ni-rich deposit under tropical conditions. This study presents geochemical, isotopic, and mineralogical data for Ni from the Serra do Puma Complex (SPC) weathering profile in Carajas (Brazil). The Ni fluxes, redistribution, and Ni isotopic fractionation magnitudes were quantified along the entire weathering profile: rock, saprock, lower and upper saprolite, and limonite. The results show that chlorite and serpentine are the primary Ni-scavenging phases in saprolite, whereas Fe oxyhydroxides are the main Ni-hosting minerals in the limonite unit. The mass balance model confirmed a global Ni gain at the weathered profile scale, with larger Ni enrichment in the upper saprolite. The isotopic dataset obtained in this study contributes greatly to the knowledge of the current Ni cycle on regional and global scales. The detailed insights into Ni isotopes in the SPC, coupled with chemical and mineralogical composition, allow for the first time a Ni mass balance and Ni isotopic values for an entire weathering profile in an Amazonian context. The Ni isotopic profile agrees with the preferential retention of light Ni isotopes in the residual material relative to the parent rock during weathering processes, with the Δ60Ni limonite-saprock of −0.72‰. In the SPC, major isotopic fractionation was notably recorded during saprolitization, while limonitization was accompanied by an overall Ni loss without significant Ni isotopic fractionation. As already observed in previous studies, heavier Ni isotopes, preferentially leached during weathering processes, can be further mobilized downward and lost from the profile or incorporated in secondary minerals in the saprolite and limonite sections. The Ni isotopic mass balance model indicated that the Ni loss from the weathered serpentinite profile was isotopically heavy, in agreement with the isotopically heavier composition of the dissolved load of Amazonian rivers. The isotopically light Ni pool, associated with the significant Ni gain encountered in the upper saprolite, is notable in the SPC weathering profile and confirms the existence of a light Ni isotope reservoir in the continent.

Rare earth elements (REEs) mobilize, fractionate, and are re-distributed during supergene processes, and thus provide a powerful tool with which to quantitatively reconstruct the effects of chemical weathering. Moreover, under certain conditions, the REEs can concentrate to levels in the regolith sufficient to form giant regolith-hosted REE deposits, that are now responsible for much of the World’s production of heavy REEs (HREEs). Understanding the supergene behavior of the REEs is an important first step towards applying the REEs as a geochemical tool and meeting the growing global demand of the REEs. Thermodynamic calculations predict that dissolution of the main REE minerals in REE-rich protoliths, namely synchysite-(Y), gadolinite-(Y), hingganite-(Y), yttrialite-(Y), allanite-(Ce), eudialyte, chevkinite-(Ce), britholite, euxenite and loparite-(Ce), should occur spontaneously during weathering. It therefore follows that a high abundance of these minerals in the protolith implies high mobility of the REEs during weathering and consequently a high potential for the discovery of economic REE resources. Dissolution of apatite is promoted by metamictization or structural distortion and could be also important at low pH. In contrast, some LREE-fluorocarbonate minerals, notably bastnasite-(Ce) and parisite-(Ce), and monazite-(Ce) are likely thermodynamically stable in acidic environments. Thus, they would be preserved in the regolith. Zircon, titanite, aeschynite, fergusonite, and xenotime-(Y) are resistant to acidic dissolution, consistent with their common occurrence as residual minerals. In the cases of the world-class regolith-hosted REE deposits in South China, the groundwater is mildly acidic to circumneutral and carbonate-rich. The REEs are consequently transported dominantly as hydrated cations and carbonate complexes, depending on the pH. The general inheritance of the REE pattern of the regolith groundwater in the clay-sorbed fraction in the regolith indicates that the REEs in regolith are scavenged from the regolith groundwater. Elemental anomalies of specific REEs in the clay-sorbed fraction are very likely caused by an anomalously high REECO3+ fraction in the corresponding regolith groundwater, suggesting a preferential uptake of the REECO3+ complexes by the clay minerals, feasibly by halloysite through intercalation as interlayer complexes. This reaction is expected to be particularly important for the sorption and enrichment of the HREEs in the regolith. Depending on the pH and carbonate concentration of the water, surface complexation on clay minerals or interlayer intercalation particularly in halloysite control the pattern of REE enrichment. Mixing of the regolith groundwater with the alkaline and carbonate-rich aquifer groundwater increases the pH and carbonate concentration and, in turn, affects the ability of the mixed water to transport the HREEs. Interplay of aqueous complexation with the regolith mineralogy significantly affects the REE fractionation and re-distribution during groundwater-regolith interaction.

本研究では，沖縄島本部半島山里の円錐カルスト地域を対象に，コックピット内の 4 地点（空中と土層）において石灰岩の溶食速度を明らかにするための野外実験を実施した．34 日間の実験の結果，石灰岩の初期段階における溶食率（%）は，コックピット内の地点ごとに異なる．すなわち，土層における溶食率（%）は設置地点の土壌含水比が高いほど大きい．これは，土層構造や基盤岩の地形の影響を受けて土壌の含水比が異なり，石灰岩の溶食に影響を与えているものと推察する．また，空中と土層に設置した石灰岩を比較すると，土層において空中よりも約 3 ～ 10 倍の速さで溶食が進行している．

Statement of problem The climate of tropical Southeast Asia includes high humidity and ultraviolet radiation that reduce the lifespan of silicone prostheses by inducing changes in their mechanical properties and color stability. Studies on the surface roughness (SR) and mechanical properties of different silicone elastomers (SEs) subjected to the natural tropical weather of Southeast Asia are lacking. Purpose The purpose of this in vitro study was to evaluate the SR, tensile strength (TS), and percentage elongation (% E) of different SEs subjected to outdoor weathering in the Malaysian climate. Material and methods Type-II dumbbell-shaped specimens (N-120) (nonweathered=15, weathered=15) were made from 3 room-temperature vulcanized (A-2000, A-2006, and A-103) and 1 heat-temperature vulcanized (M-511) silicone (Factor II). For 6 months, weathered specimens were subjected to outdoor weathering inside a custom exposure rack. Simultaneously, the nonweathered specimens were kept in a dehumidifier. Subsequently, the SR was measured with a profilometer; TS and % E were measured by using a universal testing machine. Two-way ANOVA was used to compare the means of the tested properties of the nonweathered and weathered specimens, and pairwise comparison was carried out between the silicones (α=.05). Results After outdoor weathering, the SR, TS, and % E were adversely affected by weathering in the Malaysian environment. Among the silicone materials, A-2000 showed the least TS changes (2.51 MPa), while A-2006 demonstrated significant changes in percentage elongation after outdoor weathering (266.5%). M-511 exhibited the highest mean value (2.50 μm) for SR changes. In addition, A-103 SE showed statistically significant differences in most pairwise comparisons for all 3 dependent variables. Conclusions Based on the evaluation of mechanical properties, A-103 can be suggested as a suitable silicone for maxillofacial prostheses fabricated for tropical climates. However, A-2000 can be a suitable alternative, although significant changes to surface roughness were detected after outdoor weathering.

The Physico-chemical and mineralogical properties of the Cretaceous shales of Calabar Flank southeastern Nigeria were examined for their Provenance, Paleo-weathering Conditions and Industrial Applications. Twenty samples of shale from Ekekpon and Nkporo Formations were analysed using X-Ray Fluorescence, X-ray diffraction (XRD), scanning electron microscopy (SEM) and geotechnical techniques. Results from the major oxides of elements revealed that the Nkporo Shale is enriched with SiO2 > Al2O3 > LOI > Fe2O3 > SO3 while the Ekepkon shale is also enriched in SiO2 > Al2O3 > LOI > Fe2O3 > CaO > K2O. The XRD revealed kaolinite as the major clay mineral, while other non-clay minerals are quartz, vallerite, mica, nacaphite, sodalite. The SEM shows that the Ekepkon Shale is enriched in calcium. The correlation matrix revealed SiO2 resides more in the quartz phase of the Nkporo Shales, while in the Ekekpon Shale the SiO2 is associated with the clay. The element ratios and discrimination diagrams revealed that the provenance of the shales is of intermediate to mafic igneous rocks and a tectonic setting of continental to oceanic arcs. The presence of kaolinite in the Nkporo Shale with the chemical index of alteration (CIA) values ranging from 83.58 to 96.93, indicated that the shale is derived from intensive chemical weathering in the source area. The low CIA values (37.90–76.96) in Ekenkpon Shale is attributed to CaO and calcium enrichment in the shale and the shale contains high quartz and kaolinite therefore the shale is suggested to have been derived from an intermediate to intense weathering activities in the source area. The geotechnical properties revealed that both shales are suitable for ceramic and refractory industries. The Ekenkpon Shale will be suitable for use as filling material and as raw material in cement industries. However, the shales do not meet the specifications for paper and rubber production due to the high contents of iron oxide, lime, magnesia, potash and soda.

The relationship between the Late Ordovician–Early Silurian sedimentary system, weathering, paleoclimate, and primary productivity in the Yangzi region is not well understood. In this study, by analyzing the sedimentation cycle and major trace elements of the Youc well 2 in the southeast Sichuan Basin, the coupling relationships of weathering indicators, terrigenous debris input indicators, paleoclimate, redox condition indicators, U-Mo covariance model, Mo/TOC relationship, and paleoproductivity indicators are investigated. The results show that single-well logs delineate four third-order sedimentary sequences (SS1, SS2, SS3, and SS4), two sedimentary subfacies, and four sedimentary microfacies in the Wufeng Formation–Longmaxi Formation. The weathering degree is stronger at the bottom where the climate shifts from warm–wet to cold–dry, and the seawater is in an oxidic–anoxic–oxidic–anoxic environment. While the primary productivity and material source input decreases gradually in the middle and upper part, the climate becomes dry and cold, and the seawater is in an anoxic–oxidic environment. Thus, a rock enrichment model for the organic matter shale of the Wufeng Formation–Longmaxi Formation in southeast Sichuan has been established. This provides more information on the control factors concerning organic matter enrichment and their interactions.

Currently, the overheating detection of electric system components is performed using thermal imaging devices, which depend on on-site regulation parameters, require skilled operators and suitable weather conditions. The development and application of innovative technologies to monitor hotspots has highlighted the use of sensors based on thermosensitive materials. In this study, a temperature sensor with thermochromic coating was developed. Thermochromic sensors covered with a varnish layer and nano-titanium oxide, in addition to thermochromic paint, were produced. A 23 experimental design was established to assess the performance of thermochromic sensors under artificial weathering conditions. Color measurements of the coatings were performed using the CIELAB method. Fourier-transform infrared (FTIR), UV-Vis (Ultraviolet-Visible), (thermogravimetric TGA, and Differential Scanning Calorimetry (DSC) analyses were performed on the sensors exposed to photodegradation to detect changes in the thermochromic coatings. The sensors exposed to thermodegradation, and salt spray weathering showed ΔE (total color difference) values below 1.50 points in the presence of TiO2. In comparison, the sensors exposed to photodegradation showed ΔE values above 10 points, and UV-Vis analysis revealed changes in the chemical structure of the coatings. These results demonstrate that the varnish layer and TiO2 can help minimize the degradation effects of temperature, light, and salinity.

En aquest treball s'investiga la fragmentació de blocs en despreniments rocosos, procés que influeix significativament en el risc d'aquest tipus de moviments de vessant, però que encara és poc conegut. Es parteix de dos *TFE previs sobre aquest tema. L'objectiu d'aquest treball és analitzar les condicions d'inici de la fragmentació; més concretament: 1) determinar si existeixen llindars d'energia cinètica, força normal o de pressió normal, i 2) analitzar si dits possibles llindars depenen de la geometria de l'impacte (cara, aresta, vèrtex). En este trabajo se investiga la fragmentación de bloques en desprendimientos rocosos, proceso que influye significativamente en el riesgo de este tipo de movimientos de ladera, pero que aún es poco conocido. Se parte de dos TFE previos sobre este tema. El objetivo de este trabajo es analizar las condiciones de inicio de la fragmentación; más concretamente: 1) determinar si existen umbrales de energía cinética, fuerza normal o de presión normal, y 2) analizar si dichos posibles umbrales dependen de la geometría del impacto (cara, arista, vértice). This paper investigates the fragmentation of blocks in rockfalls, a process that significantly influences the risk of this type of landslides, but which is still poorly understood. It starts from two previous TFE on this subject. The objective of this work is to analyze the fragmentation initiation conditions; more specifically: 1) determine if there are kinetic energy, normal force or normal pressure thresholds, and 2) analyze if said possible thresholds depend on the geometry of the impact (face, edge, vertex).

Natural building stones, used as floor cladding stones in outdoor applications in cold regions, are negatively affected by freezing and thawing processes, and this reduces the service life of the stone. The aim of this study is to reveal the change of abrasion resistance of natural stones determined by the wide wheel abrasion test (W-A) with laboratory freeze-thaw (FT) tests. For this purpose, FT tests were applied up to 84 cycles on 23 groups of samples, mainly consisted of carbonate rocks. According to the results, no significant decrease was determined in the dry unit weight (gamma(d)) value, but significant decreases were obtained in open porosity (n) and P-wave velocity (V-P) values. It has been revealed that W-A values are also significantly affected by increasing FT cycles and increased up to about 14%. It was concluded that the increase was evident up to 35 FT cycles, and after this level, the increase continued with a decrease.

Silicification in New Caledonian pseudo-karsts developed on peridotite was assessed using δ18O and δ30Si pairs on quartz cements. The objective was to document the chronology of pseudo-karst development and cementation relative to geomorphic evolution. The latter began at the end of the Eocene with the supergene alteration of peridotites and the subsequent formation of extended lateritic weathering profiles. Neogene uplift favoured the dismantling of these early lateritic profiles and valley deepening. The river incision resulted in (i) the stepping of a series of lateritic paleo-landforms and (ii) the development of a pseudo-karst system with subvertical dissolution pipes preferentially along pre-existing serpentine faults. The local collapse of the pipes formed breccias, which were then cemented by white quartz and Ni-rich talc-like (pimelite). The δ30Si of quartz, ranging between −5‰ and −7‰, are typical of silcretes and close to the minimum values recorded worldwide. The estimated δ18O of −6 to −12‰ for the fluids are lower than those of tropical rainfall typical of present-day and Eocene–Oligocene climates. Evaporation during drier climatic episodes is the main driving force for quartz and pimelite precipitation. The silicification presents similarities with silcretes from Australia, which are considered predominantly middle Miocene in age.

Carbon (C), nitrogen (N), and phosphorus (P) stoichiometry and their allometric relationships in soil and plants are hot topics that attract a lot of attention, while those rocks that form soils are often neglected. Weathering is a common geological phenomenon that may significantly influence the nutrient composition and release of nutrients from rock and its inherent soils. This study presents C, N, and P concentrations data as well as microscope petrological photographs of fresh and weathered sandstones from Longhushan World Geopark in SE China, in an attempt to investigate C, N, and P stoichiometry of rocks before and after weathering and discuss the driving mechanisms. The results show that weathering significantly decreased rock C, C/N, and C/P concentrations, slightly decreased N and N/P concentrations, and slightly increased P concentration. Microscope observations show that fresh sandstones contain calcite, apatite, microplagioclase, and organic matter, while weathered sandstones feature apatite and organic matter. The flexible allometric relationships and mineral changes before and after rock weathering indicate that chemical mechanisms, such as dissolution of carbonate and hydration of microplagioclase, have changed the existence form of C, N, P and, thus, significantly influence rock C, N, and P stoichiometry. This stoichiometry feature can be in turn used to reflect the regulation effect of rock weathering.

Clay-rich red soil profiles developed in different lithologies in Indonesia were assessed using geochemical evidence, the migration coefficient and elemental ratios. Our study aimed to ascertain the source of red soil materials and to investigate the elemental behavior in tropical soils. The results indicate carbonate profiles were derived from in situ weathering, while basalt profiles, even though having close affinity to their bedrock, also showed the contribution of external materials. Elemental behavior was dynamic with carbonate profiles indicating relatively constant depletion and even distribution. Basalt profiles indicated uneven distribution with enrichment and depletion. The variation in elemental behavior was linked to difference in lithologies, age and physiochemical conditions. Our findings support evidence of both residual and multiple source parent materials in red soil formation and provide insights into elemental behavior during weathering, while highlighting the influence of external materials’ contribution in deeply weathered tropical soils.

The demand for a load distributive compression anchor (LDCA) in construction sites has been increasing, owing to its high bearing capacity and removable steel strands. As an LDCA comprises multiple anchor bodies and unbonded steel strands, the load applied to the strands generates a distributive compressive stress in the grout, preventing high concentration of grout–ground shear stress. Unlike in the conventional anchors, in an LDCA, independent load transfer of each anchor body induces interference effect between adjacent anchor bodies. Therefore, for an efficient design of an LDCA, it is necessary to investigate the load transfer mechanism considering the effect of multiple anchor bodies. In this study, a series of anchor pull-out field tests was conducted for LDCAs consisting of a single anchor body, and double and triple anchor bodies spaced by 1, 2, and 3 m. According to the test results, the LDCA showed a stiffer load–displacement behavior with an increase in the number and spacing of the anchor bodies. The multiple anchor bodies of the LDCA generated an overlapping of the grout axial load and induced its rapid dissipation, increasing the grout–ground shear stress. This interference effect was more clearly observed with a decrease in the anchor body spacing.

The geochemical composition and magnetic susceptibility (MS) of three sections (Weinan, Jingchuan and Jingbian) in the central Chinese Loess Plateau, located along a north-south climate gradient, were analyzed at high resolution in order to reconstruct changes in weathering intensity and hence Asian monsoon evolution during the Holocene. The results show distinct differences in element composition between the loess and paleosol layer, as well as spatial differences which reflect changes in mean annual temperature and annual precipitation along the climatic gradient. The measured major element compositions, combined with the results of previous research, indicate that the provenance of the Holocene loess-paleosol sequences in the central Chinese Loess Plateau was constant over time and space. The degree of chemical weathering in the study area is relatively weak and at an intermediate weathering stage. Based on a magnetic susceptibility age model, the East Asian summer monsoon changes recorded by the loess-paleosol sequences show a distinct two-stage pattern of evolution, with a gradual increase during 13.1–8.5 ka and a gradual decrease thereafter. Comparison of the results with climate records from elsewhere indicates that the East Asian monsoon evolution was mainly controlled by changes in Northern Hemisphere summer insolation and ice sheets.

Water affects the susceptibility of stone to alteration by facilitating physical, chemical and biological weathering. Stone properties determine water transport and retention, but it is also expected that biofilms and extracellular polymeric substances could alter the water-stone relationship. A lot of research on this subject has been carried out on soils, but the effect on stones is understudied. For this reason, three sedimentary building stones, Ernzen, Euville and Savonnieres, each with a different pore size distribution, were biofouled with cyanobacteria. Their relationship with the stone material was investigated by optical and electron microscopy, and the effect of cyanobacterial biofilms on water transport and retention was studied. The results showed that the cyanobacteria primarily colonize the building stones on the outer surface and have a limited effect on the water transport properties. They slightly reduced the capillary coefficient and drying rate of the stones, but enhanced the water content in the stone and increased water vapour sorption. They induced (near) hydrophobic conditions, but had no measurable effect on the gas permeability and water vapour diffusion. Moreover, swelling and shrinkage of the biofilms were observed, which could potentially induce physical weathering. It is expected that these changes could influence other forms of weathering, such as freeze-thaw weathering and salt weathering.

Considerable research has been conducted over the past decade by oil sands mining companies to improve the dewatering and strength properties of fluid fine tailings deposits in an effort to meet the regulatory and closure requirements. Commercially employed dewatering treatment technologies (inline flocculation, thickening, and centrifugation) may not be sufficient to develop the strength for the creation of trafficable landscape without the use of soft soil capping technologies. These treated tailings are continuously deposited creating soft and saturated deep deposits. Seasonal weathering may be an additional promising technology to further dewater the treated tailings and promote the development of shear strength at the surface. This paper presents the effects of seasonal weathering on dewatering and strength that were investigated by performing multiple cycles of freeze–thaw and alternate drying–wetting cycles on two types of treated tailings deposit. The results indicate that multiple cycles of seasonal weathering significantly increased the dewatering and strength properties. However, different parameters such as freezing gradient, number of seasonal cycles, and pore water chemistry play an influential role in changing the magnitude of the strength. The results also suggest that a minimum threshold strength value is required where the effects of rainfall rewetting had a minimal impact on strength reduction (the strength corresponding to the moisture content approaching the plastic limit).

Fungi actively enhance the local dissolution of nutrient-bearing minerals through the combined biomechanical and biochemical actions of their hyphal tips to obtain mineral-bound inorganic nutrients (MINs). However, little is known about the dynamic processes underlying hyphal tip-mineral interactions. Here, we assess the adhesive force between a single hypha of the common fungus Talaromyces flavus and the Fe-bearing silicate lizardite and quartz (as a control), as well as hyphal tip-induced lizardite weathering and hyphal Fe uptake. We showed that T. flavus hyphae formed their maximal adhesive force with lizardite at the growing tips, reaching 6.11 ± 0.69 nN after a contact time of one minute. The adhesive forces of the tip-lizardite interface within two minutes were > 2.65 times stronger than those of the tip-quartz interface. Examination of the hyphal tip-lizardite interface after 18 h indicated the formation of dissolution channels with a depth of 27.7 ± 8.0 nm. Furthermore, the hyphal tips resulted in an altered lizardite up to 46 nm. The thickness of the altered lizardite increased to ∼130 nm after contact with the mature regions of the hyphae for ∼173 min. And the altered lizardite was found to have depleted Fe levels that increased with increasing contact time. The total content of Fe in T. flavus associated with the lizardite surface after 18 h was 52.98 ± 12.20 nmol mg-1, which was 6 times greater than the total amount of Fe in quartz surface-associated T. flavus after 24 h of culture. These results demonstrate that fungi access MINs by the active development of a strong adhesive force with target minerals through their hyphal tips, effectively enabling fungi to flourish in heterogeneous environments and be major geological agents for biogeochemical transformation.

Degraded water quality and environmental impacts caused by weathering of sulfide-bearing mine wastes are a legacy remaining at many historical mine sites. Release and mobilization of toxic metals (e.g., Zn and Cd) in mine drainage are often associated with weathering of primary sulfide minerals and precipitation and dissolution of secondary minerals. This study aims to couple field-scale measurements of physicochemical parameters with μm- and nm-scale mineralogical characterization to investigate sphalerite weathering and controls on Zn and Cd migration in an uncovered mine waste-rock pile. Elevated concentrations of Zn and Cd, potentially harmful to the receiving environment, were detected in waste-rock pore water and seepage. A suite of analytical techniques, including scanning electron microscopy – energy dispersive X-ray spectroscopy (SEM-EDS), scanning transmission electron microscopy (STEM) with EDS, electron microprobe analysis (EMPA), and synchrotron-based micro X-ray fluorescence (μ-XRF) mapping and micro X-ray absorption near edge structure (μ-XANES) spectroscopy were utilized in a high-resolution investigation of elemental- and secondary-mineral associations with sphalerite grains. EMPA and μ-XRF elemental maps and STEM investigations show depletion of Zn, Fe, S, and Cd, local enrichment of Cu, and distinct dissolution pits at the margins of sphalerite grains. Using μ-XANES, the speciation of solid phases containing Zn, Cu, Fe, and S indicates the dominance of primary sphalerite with microscopic inclusions of chalcopyrite, along with sparse occurrence of secondary Cu-bearing sulfides formed during weathering. These results suggest sphalerite oxidation leads to congruent dissolution without formation of distinct secondary-mineral coatings. Sphalerite weathering significantly contributes to elevated aqueous concentrations of Zn and Cd. Field-scale observations and mineralogical investigations indicate common occurrence of Fe-oxyhydroxides in the waste-rock pile. Seepage chemistry and surface complexation modeling results suggest that pH-dependent variations in reactions on the surfaces of the Fe-oxyhydroxides control aqueous concentrations of Zn and Cd, and the Zn/Cd ratio in the seepage. This work highlights the importance of understanding the mechanisms of sulfide-mineral oxidation and subsequent surface precipitation and adsorption, such that appropriate remediation action can be implemented to limit mobilization of metals to sensitive ecosystems.

Subaerial physical, chemical and biological weathering processes are significant contributors to mountain landscape development worldwide, and over long time scales. This paper reports on pseudokarst features formed by different subaerial weathering processes on a high-elevation basalt plateau surface in the Maloti–Drakensberg mountains of eastern Lesotho, southern Africa. Different mesoscale landforms identified on this plateau surface include enclosed depressions (containing seasonal pools) that are morphologically similar to karstic solutional features. Such basalt pseudokarst landforms have not been previously described. This study uses field data on depression morphometry, sediments, water chemistry and rock surface hardness to explore the varied subaerial weathering and erosion processes contributing to pseudokarst depression development. Results show that physical, chemical and biological weathering and erosion processes in combination can impact on the basalt land surface in widening and deepening these depressions. An evolutionary model for pseudokarst depression development proposes that different weathering processes in combination within the ‘critical zone’ cause changes in depression morphology, and that there are significant feedbacks between bedrock, weathering, and the development of distinctive micromorphological forms. It is likely that similar pseudokarst landforms from other locations with non-carbonate substrates have been under-reported in the literature.

International audience; AimsRare earth elements (REEs) and normalized REE patterns determined in plant and soil samples represent powerful tools to trace biogeochemical processes during weathering, soil genesis and processes in the rhizosphere, and thus publications reporting REE concentrations and normalized REE patterns in soil systems and plants are rapidly increasing.MethodsA normalized REE pattern allows for the recognition of anomalous concentrations of an individual REE. In the literature, anomalies are predominantly reported/focused for/on the redox-sensitive elements cerium (Ce) and europium (Eu) that can shift their oxidation state during interactions with organic and inorganic soil phases and the biological processes affecting their mobility in soil and uptake by plants. Thus positive Eu anomalies in plants are often interpreted as a consequence of reduction of Eu3+ to Eu2+ in the rhizosphere followed by a preferential uptake of Eu2+.ResultsDue to an analytical artefact in ICP-MS analysis, a false Eu anomaly may be reported. This can be avoided by using a barium (Ba) interference correction. We draw attention to the possibility of this problem and to being aware of its potential occurrence when Eu anomalies are reported.ConclusionsWe recommend (i) including information on how this potential problem was dealt with in the Materials and Methods section of articles and (ii) how to implement Findable Accessible Interoperable and Reusability (FAIR) guiding principles in that section (including data availability in an open repository).

This work presents the systematic investigation of K contents and stable K isotopic compositions of surface waters, groundwater, wastewaters, suspended particles, bed sediments, and fertilizers in the Upper Mun Rive catchment, northeast Thailand. This area is of particular interest because its abundant potash deposits and intensive agricultural activities and urbanization, therefore this will improve our understanding whether the K isotope is robust enough to resist evaporite dissolution and anthropogenic disturbances on tracing silicate weathering in the highly weathered tropical region. The dissolved loads in surface waters and shallow groundwater display the large variation in δ41Kdiss values from −0.54‰ to +0.09‰ relative to suspended particles (−0.60‰ to −0.41‰), river bed sediments (−0.54‰ to −0.47‰), the upper continental crust (UCC, −0.44 ± 0.05‰), which agrees with the fact that 39K is preferentially retained in weathering products during silicate weathering. The wet and dry seasons difference ranging from −0.05‰ to +0.10‰ δ41K, which is slightly greater than our long-term analytical uncertainty of ±0.06‰. There is likely a limited K input from evaporites dissolution due to weak correlation between δ41Kdiss values and Cl concentrations or Cl/K ratios in the UMR and world rivers, while a major tributary Takhong River is clearly influenced by the contribution of domestic sewage with lower δ41K and higher δ15N values. Based on a mass balance of K budge, the dissolved K in the UMR is mostly (>90%) derived from silicate weathering in the unpolluted area, this is consistent with previous studies of large river basins, and the evaporite dissolution and other non-silicate sources may not strongly influence dissolved K and δ41Kdiss values in rivers, even in evaporite-rich catchment. Therefore, K isotopes cannot be used as lithological tracers in catchments, rather the K isotopic fractionation mainly occurs during silicate weathering, such as the formation of secondary minerals which favor light isotope. Hence, the mechanism of K isotopic fractionation linked to secondary minerals K uptake needs further consideration. Overall, these results clearly show that K isotopes could be an ideal indicator to constrain silicate weathering processes and anthropogenic inputs at catchment scale.

Pliocene-aged carbonaceous rocks of varying thicknesses, alternating with siliciclastic and carbonate rock units, are located on the northern border of the Çameli-Acıpayam basin (in southwestern Turkey), which is filled with thick Neogene sediments. Organic and inorganic geochemical properties of carbonaceous rocks were examined to evaluate their hydrocarbon production potential and paleo-depositional conditions (provenance, paleoclimate, paleosalinity, paleoredox, weathering, heavy metal contents, etc.). Based on organic geochemical analysis, carbonaceous rocks show good to excellent source rock potential and have gas production potential. Organic substances are mostly of allochthonous origin, and their thermal maturity degree is quite low. Carbonaceous rocks have a high amount of inorganic substance (minerals) composed of quartz, clay + mica minerals (mostly illite and a lesser amount of smectite, chlorite, and kaolinite), feldspar, and opaque minerals (pyrite and ilmenite). Although carbonaceous rocks have similar major oxide and trace element concentrations, they show clear differences in terms of Fe2O3, MgO, and some heavy metals (such as Ni, Cr, Co, V, and Sc). The major oxide, trace element concentrations, various element ratios of carbonaceous rocks bear the characteristics of mafic/ultramafic magmatic rocks formed on the active continental margin. In addition, carbonaceous rocks were precipitated in a brackish water environment under oxic conditions. The sediments, which were rapidly stored without recycling in the deposition environment where hot/humid climatic conditions are effective, did not undergo intense decomposition in the source area.

The environmental availability of mineral nutrients plays a role in the adaptation and evolution of soil fungi and fungus-plant symbiotic systems. As nutrient availability is different from soil to soil, it is expected that the most adapted fungi can express multiple genes to promote different mechanisms of mineral attack and of metabolic routes to maximize the use of nutrient resources at the lowest energy cost. Microcosm experiments of Paxillus involutus growing on muscovite, phlogopite and K-exchanged vermiculite as K sources were carried out for 21 days. Gene expression analysis indicated that the level of K-deprivation stress was muscovite > phlogopite >> K-vermiculite. Genes and functions overexpressed in the experiments indicated meaningful metabolic activities including K extraction and transport. SEM-EDS and micro-XRD (∼1.15 mm resolution) analysis of mineral surfaces and chemical analysis of agar and mycelium indicated weathering processes and K uptake in good agreement with gene expression analysis. In many areas, P. involutus caused physical damage to the minerals without any apparent chemical attack, consisting of tracks of different depth, from

Flame treatment is an ancient technique for surface protection of wood. Further processing of charred wood elements depends on aesthetic and protective requirements. This study presents some general properties and weathering behaviour of the Norway spruce (Picea abies (L.) Karst.) and the European larch (Larix decidua Mill.), protected by variations of sanding, charring, charring + brushing, and coating treatments. Charring and charring + brushing reduced the original mass of the samples by up to 8% and notably changed their colour (ΔE* ≤ 75). A study of chemical properties showed that charring dehydrated the wood and degraded lignin and hemicelluloses. The surface roughness of the wood after charring and charring + brushing increased by as much as 560%, while coating with waterborne acrylic high build stain had no effect on the roughness of these surfaces. The type of surface treatment of the wood did not affect the uptake of the coating in the wood samples, but the uncoated and coated spruce wood absorbed more water than larch wood. Higher water absorption was observed in the samples treated by charring, and it decreased when the char layer was removed by brushing. The film of a waterborne high build stain reduced water uptake only for surfaces treated by sanding and charring + brushing. Larch wood exhibited higher surface hardness (EHz ≤ 1.70 MPa) than spruce wood (EHz ≤ 0.89 MPa), with the brittle char layer reducing the determined hardness of the tested surfaces. During two years of natural weathering, the char layer was removed from the wood surface, even if the samples were additionally coated. The greatest colour changes during weathering were observed on samples treated by sanding (ΔE* ≤ 60) and sanding + coating (ΔE* ≤ 33), followed by samples treated with charring + brushing (ΔE* ≤ 10) and samples treated with charring (ΔE* ≤ 9). In summary, treating wood by charring in combination with brushing was the best wood protection technique.

This paper presents the results of a laboratory simulation of a subarctic climate carried out in climatic chamber. Realistic daily and seasonal cycles of temperature of a regular subarctic continental climate without dry seasons (Dfc) were simulated and the physical/mechanical properties and performance of the slates were assessed. The slate was selected because of its use as cladding and roofing material in cold regions. Mechanical performances before and after Dfc climate simulation were evaluated through point load index, uniaxial compression, flexural strength and anchor rupture load. A decrease in these mechanical features between 9 and 50% with respect to the initial strengths has been registered. Other physical parameters such as apparent density, open porosity and water absorption were evaluated. The tests showed an increase in open porosity (+72%) and a decrease in bulk density (−0.7%). The results highlighted a predominantly physical decay and mechanical performance decreasing with a relevant lowering in strength without the detection of chemical–mineralogical alterations. Moreover, artificial sun exposure reproduced the weak solar radiation that characterizes the Dfc climate. This was carried out to assess the aesthetic characteristics of the slate, since discoloration under sun exposure was supposed to occur but the slates did not exhibit substantial color changes.

Once discharged into the environment, plastics debris are unavoidably subjected to natural weathering processes. Unfortunately, the impact of weathering on the aggregation tendency and kinetics of nanoplastics in complex environmental matrices is poorly understood. Here, we investigated the influence of weathering as induced by UV and O3 treatments, on the aggregation of polystyrene nanoparticles (PSNPs) in simulated waters containing representative organic molecules (humic acid, lysozyme, and alginate) and in natural waters. Results showed that UV/O3 weathering-induced physicochemical transformations of PSNPs, particularly the formation of oxygen-containing functional groups and the increase in hydrophilicity, altered the aggregation state of PSNPs to different extents. The presence of organic molecules destabilized the UV-aged PSNPs with strength of lysozyme > alginate > humic acid, owing to the decrease of sorption of macromolecules on their surface. Differently, the O3-aged PSNPs displayed strong stability in the absence or presence of organic molecules (except for lysozyme), probably due to steric repulsion arising from the leakage of endogenous organic matters. This work demonstrates that the aggregation behavior of PSNPs is determined by the complex interplays among weathering, natural organic matter, and solution chemistry, and provides significant insights into the fate and transport of PSNPs in realistic scenarios.

The effects of lignin on soybean seed quality have been studied since the early 1990s. Initially, higher lignin content in the seed coat was associated with greater resistance to mechanical damage by the seeds. Later, positive relationships of lignin content in the seed coat were associated with tolerance to stresses caused by weathering in pre-harvest, resulting in improved seed quality. Additional studies have shown that higher lignin content in the pod wall of soybean is also related to production of seeds with high physiological and sanitary qualities. Colored soybean seeds (black or brown) are known to have higher seed quality due to higher lignin content in the seed coat; in addition, the presence of anthocyanin in the seed coat of colored seeds also contributes to improve seed quality. Finally, the effects of boron on lignin synthesis are also highlighted in this review article. As demonstrated in this review article, lignin content in the seed coat and pod wall of soybean plays an important role in relation to physical, health, and physiological seed qualities. These parameters should be considered in studies related to evaluation of the quality of soybean seeds as affected by genetic factors. These parameters should also be strongly considered for inclusion in breeding programs to improve soybean seed and grain quality. Resumo: Os efeitos da lignina na qualidade da semente de soja vêm sendo estudados desde os primeiros anos da década de 1990. Inicialmente, verificou-se que maiores teores de lignina no tegumento da semente estavam associados a maior resistência a danos mecânicos pelas sementes. Posteriormente, relações positivas do teor de lignina no tegumento das sementes foram associadas à tolerância aos estresses causados pelo intemperismo na fase de pré-colheita, resultando em melhor qualidade das sementes. Estudos adicionais mostraram que maiores teores de lignina na parede da vagem da soja também estão relacionados à produção de sementes com altas qualidades fisiológicas e sanitárias. Sementes de soja coloridas (pretas ou marrons) são conhecidas por possuírem sementes de maior qualidade devido ao maior teor de lignina no tegumento; além disso, a presença de antocianina nos tegumentos das sementes coloridas também contribui para a melhoria da qualidade das sementes. Finalmente, os efeitos do boro na síntese de lignina também são destacados neste artigo de revisão. Conforme demonstrado neste artigo de revisão, o teor de lignina no tegumento e na parede da vagem da soja desempenha um papel importante relacionado às qualidades físicas, sanitárias e fisiológicas das sementes. Esses parâmetros devem ser considerados em estudos relacionados à avaliação da qualidade de sementes de soja, afetadas por fatores genéticos, pois também devem ser fortemente considerados para serem incluídos em programas de melhoramento, para melhorar a qualidade de sementes e grãos de soja.

Deep atmospheric convection in the Indo-Pacific Warm Pool (IPWP) represents a major source of heat and moisture, thereby affecting the global climate, but its past changes remain debated. Here, we present sub-millennial clay mineralogy and elemental records spanning the last 40 kyr from within the IPWP. From these data, we infer millennial-scale fluctuations in precipitation, with generally lower precipitation during Heinrich Stadials 1-4, corresponding to El Niño-like conditions. Higher precipitation coincided with the warm interstadials, accompanied by La Niña-like conditions. Moreover, our record indicates the lowest precipitation occurred during the late Holocene, supporting the hypothesis of a stronger-than-modern Walker circulation during the Last Glacial Maximum. In combination with other proxy records and TraCE-21 modelling results, we recognize a distinct spatial heterogeneity of precipitation within the IPWP, resulting from the dominant influences of the ENSO-like system and migration of the Intertropical Convergence Zone in the eastern and western IPWP, respectively. Key Points We present sub-millennial clay mineral and elemental records from the Indo-Pacific Warm Pool spanning the last 40 kyr Our records indicate higher precipitation during La Niña-like conditions and lower precipitation during El Niño-like conditions Different patterns and controls on precipitation variability between the eastern and western Indo-Pacific regions are revealed Plain Language Summary Tropical rainfall systems in the Indo-Pacific Warm Pool (IPWP) play a significant role in transferring energy and moisture. However, their millennial-scale variabilities in precipitation during remains poorly understood. Here, we provide sub-millennial sediment mineralogy and elemental reconstructions spanning the last 40,000 years from a sediment core in the IPWP. We infer that variability in precipitation induced by atmospheric convection in the IPWP is the main factor controlling the variability in our data through time. Hence, we interpret our records to reflect sub-millennial fluctuations in precipitation, with lower precipitation during cool stadial periods and higher precipitation during warm interstadials. Such variability corresponds to the changing zonal state of the tropical Pacific atmosphere-ocean system, in a pattern similar to the modern-day. Additionally, our record indicates that precipitation was weaker during the late Holocene than during the Last Glacial Maximum (LGM), suggesting that the Pacific atmospheric zonal circulation was stronger during the LGM than today. Furthermore, a model-data comparison reveals distinct spatial heterogeneity in the precipitation changes, with precipitation in the eastern IPWP (West Pacific) likely controlled mostly by the tropical Pacific atmosphere-ocean system, whereas precipitation in the western IPWP (Indian Ocean) was driven by latitudinal movement of the Intertropical Convergence Zone.

Vegetation plays a key role in the hydrological and biogeochemical cycles. It can influence soil water fluxes and transport, which are critical for chemical weathering and soil development. In this study, we investigated soil water balance and solute fluxes in two soil profiles with different vegetation types (cushion-forming plants vs. tussock grasses) in the high Ecuadorian Andes by measuring soil water content, flux, and solute concentrations and by modeling soil hydrology. We also analyzed the role of soil water balance in soil chemical weathering. The influence of vegetation on soil water balance and solute fluxes is restricted to the A horizon. Evapotranspiration is 1.7 times higher and deep drainage 3 times lower under cushion-forming plants than under tussock grass. Likewise, cushions transmit about 2-fold less water from the A to lower horizons. This is attributed to the higher soil water retention and saturated hydraulic conductivity associated with a shallower and coarser root system. Under cushion-forming plants, dissolved organic carbon (DOC) and metals (Al, Fe) are mobilized in the A horizon. Solute fluxes that can be related to plant nutrient uptake (Mg, Ca, K) decline with depth, as expected from biocycling of plant nutrients. Dissolved silica and bicarbonate are minimally influenced by vegetation and represent the largest contributions of solute fluxes. Soil chemical weathering is higher and constant with depth below tussock grasses but lower and declining with depth under cushion-forming plants. This difference in soil weathering is attributed mainly to the water fluxes. Our findings reveal that vegetation can modify soil properties in the uppermost horizon, altering the water balance, solute fluxes, and chemical weathering throughout the soil profile.

The development of porosity during rock weathering is a key process controlling nutrients release, water holding capacity available for plants and water flow. Here we used X-ray Computed Tomography (XRCT) and 14C PolyMethylMethAcrylate (PMMA) autoradiography to show how cracks are created and enlarged during initial weathering stages (saprock and saprolite) of granodiorite in southern Brazil (Viama similar to o - RS). The physical evolution is characterized by imaging the pore network, using 14C-PMMA and XRCT methods. Combined with bulk porosity measurements, they highlight the increase in porosity with the degree of weathering (un-weathered rock phi = 1.66 %, saprolite phi = 11.7 %). This increase is related to the joint increase of the density of the cracks (unweathered rock D = 0.28 mm-1, saprolite D = 0.94 mm-1) and of the average opening of the microcracks (unweathered rock w = 2.4 mu m, saprolite w = 3.9 mu m) and macrocracks (un-weathered rock w = 176 mu m, saprolite w = 400 mu m). However, these average crack openings do not account for the variability of the openings that govern the flows, characterized here by specific distribution ranging from the submicrometre to the centimetre scale. The results highlight that the pore network of the un-weathered rock plays a key role in the initial stages or incipient weathering. The density and aperture and cracks increase following the subcritical cracking concept and new pores are formed by chemo-mechanical processes. The presence/absence of initial fractures in the regolith is certainly a key parameter controlling the weathering of different rock types (mafic vs felsic).

This thesis project revolves around the last days of an abandoned building in decay, facing demolition. It is situated in Värtahamnen, a harbor area in Stockholm. The area is the subject of a major urban planning project in the upcoming decade. In my project my aim is to contemplate this condition of of a building and how to approach and use the ephemerality of architecture and design in the creative process. By extracting different material behaviors caused by decay and exploring them experimentally, a diverse “buffet” of design concepts and methods are presented. The project also orbits around the subject of preservation, a topic commonly debated during interventions in the built heritage. Instead of taking a stand for or against the demolition of the building, the field of experimental preservation is used as a theoretical and methodological background in the design process, as a way to expand the scope on how to navigate and work artistically with preservation. In conclusion, this project tries to revise our perspective on the concept of decay as something destructive and instead suggest the creative potential in understanding it. It also contributes with reflections and speculations on how we can find new creative strategies for taking the whole lifespan of a design project into account already from the beginning.

Weathering of wood surfaces remains a major problem when timber is used in exterior exposures. Surface degradation starts almost immediately, mainly induced by ultraviolet light (UV). This surface deterioration often leads to a series of physical, microscopic, and chemical changes that cause dramatic declines in surface appearance. Although traditional surface protection systems can limit UV degradation, all existing surface treatments have drawbacks. Opaque coatings such as paint totally mask the natural appearance of wood, which is not desirable when the purpose of treatment is to maintain the natural wood appearance. Less robust clear coatings often provide only 12 to 24 months of protection and must be reapplied to provide continued protection. The desire to prolong wood performance in exterior applications has created continuing interest in developing more effective additives and treatments to reduce wood weathering. One alternative approach to wood surface modification for UV protection is the use of nanotechnology. Nano-particles have unique properties that may have promise for surface protection, but our understanding of the mechanisms by which these materials perform remains limited. This study was performed using only nano-particles to simplify the experiments and help delineate the direct role of the nano-particles. The characteristics of nano-particles in relation to wood protection against UV light were explored. The most effective nano-particles were conducted to evaluate the nano-particle/wood interactions.

This thesis deals with the question of the influence of climate on archaeological monuments beneath the pavement of the III. courtyard of Prague Castle. The complex archaeological site is threatened by the effects of several climatic factors, especially water and temperature changes, which cause weathering processes, and the historical building material in this area is subsequently degraded. The theoretical part of this thesis first deals with the study of historical building materials in the excavation area, with a focus on marlstone and clay slate, which are most susceptible to various types of weathering. Subsequently, degradation processes that affect the state of the present material are discussed, particularly processes related to water penetration through the material, chemical weathering caused by salt crystallization, and swelling of clay minerals, a process that often occurs in clay slate. The last chapter of the theoretical part outlines the impact of future climate change on the action of these processes. The practical part of this thesis focuses on research into frost and salt weathering cycles, particularly the determination of the frequency of cycles in one year of continuous measurement. Moisture and temperature values over time from sensors that are evenly distributed throughout...

Industrialization and changes in the landscape have disturbed natural geochemical cycles of carbon and other elements significantly for several centuries. Fossil fuel emissions are the main contributor, along with deforestation and cement production. Projection of future trends in atmospheric CO2 and global carbon flows, under human disturbance, requires understanding of the natural exchanges between atmosphere, marine and terrestrial ecosystems, and geosphere pools. Regulation of the rates of flux in the global carbon cycle occur in enumerable biogeochemical processes, but overall through major feedbacks in the biogeochemical cycle of carbon through weathering, photosynthetic fixation, respiratory metabolism, and the ocean calcium carbonate buffering system. Mathematical computer models have become the means by which the complex, biogeochemical processes of atmosphere, land, and oceans can be represented, quantified, and used to describe the past, present, and future dynamics of the Earth's carbon cycle.