Bulk Content Research Articles

Bio Fiber Odyssey

Abstract: Solid waste management presents a significant challenge for modern society. This research project aims to address this issue by utilizing agricultural waste—specifically, sugarcane bagasse, banana fibers, and dry leaves—to manufacture handmade paper. The fibers are collected, sun-dried, and cleaned in a water vat to remove dust and impurities. They are then cooked with a 10% caustic solution in a pressure cooker and subsequently blended for different time intervals. To achieve discoloration and further purification, a diluted Clorox solution is employed. Three types of paper are produced: one using only the raw fibers, another with the addition of 2% calcium carbonate and 2% starch, and a third with 5% of these additives. The papers are then dried and ironed to enhance smoothness. Various properties, including GSM, pH, thickness, bulk, and moisture content, are measured. Papers made from bagasse fibers are heavier and more suitable for rough use, while those made from banana fibers are softer and ideal for applications such as tissues and wipes. This eco-friendly process not only utilizes agricultural waste but also consumes minimal electricity.

A 56 ka eruptive history of Sartori Mud Volcano in the Calabrian Accretionary Prism, Mediterranean Sea

Mud volcanoes (MVs) are geological structures from which mud breccia consisting of fluids and solids from the Earth's sub-surface are typically discharged periodically. MVs are associated to converging plate boundaries such as the African-European collision zone in the Mediterranean Sea. While much research has been conducted on the global distribution, morphology and current activity of MVs, studies in distinguishing the history and periodicity of MV activities are limited. This study presents a comprehensive analysis of the chronology of mud eruptions of the submarine Sartori MV located in the Calabrian Accretionary Prism in the Central Mediterranean Sea at ∼1,900 m water depth. Seafloor bathymetry and backscatter mapping combined with multi-proxy sediment analysis of 16 sediment cores collected in the area of the MV indicate mud breccia deposits from six individual eruptive phases. Radiocarbon ages of planktonic foraminifera, ages of interbedded tephra layers, identification of the Holocene sapropel marker horizon S1, and correlation with calculated sedimentation rates of hemipelagic sediments revealed that these six mud eruption phases occurred during the last ∼56 ka. The mudflow deposits of the individual mud eruption phases differ slightly in their bulk contents of organic carbon and nitrogen, suggesting that the composition of the mud breccia varied between the individual eruptive phases to some extent. The duration of the quiescent phases between the individual eruptions varied from ∼1.4 ka to ∼12.2 ka. The seafloor backscatter data suggest that only the mudflows that were mobilized between ∼56 and 22 ka cover the surroundings of Sartori MV over a wide area. The mudflows generated during more recent eruptive phases remained confined to the central area and the immediate vicinity of the MV. This suggests that MV activity was attenuated, and smaller amounts of mud were produced, during the deglacial sea level rise and Holocene sea level high-stand. Eruptive phases of Sartori MV did not coincide with the eruptions of magmatic volcanoes in the region, and a correlation with earthquake events is also not evident due to the sparse documentation of historical events. It is proposed that internal processes such as pressure release from overpressured mud chambers are significant drivers of the periodic activity of Sartori MV. This study documents the periodicity and dynamic activity of a MV, and reveals the interplay between internal driving processes and external influencing factors over geological timescales.

Variations in mineral composition and the weathering crust zoning of the REE-Nb chuktukon deposit (Chadobetsky uplift, Krasnoyarsk region)

The Chuktukon REE-Nb deposit occurs within the carbonatite laterite supergene zone Chadobets upland, South of the Siberian craton. A unique laterite profile up to 600 m thick was identified by deep drilling. The laterite developed upon ultramafic lamprophyres and Ti-Th-REE-rich carbonatites. Here we report new mineralogical and geochemical data on carbonatites and laterites that reveal the evolution of supergene processes in the Chuktukon deposit within vertical zonation: (from top to bottom): 1) laterite horizon or ferruginous cap rock (ferricrete); 2) loose ochreous weathering products (ochre zone or regolith zone); 3) secondary phosphate enrichment horizon (apatite-rich zone); 4) unevenly altered disintegrated carbonatites. The bulk contents of CaO and P2O5 increases from primary carbonatite upwards due to the crystallization of carbonate-fluorapatite, and decrease in near-surface horizon due to the high leaching of rocks. The total REE2O3 content is highest in the rocks of the regolith zone and the enriched zone due to the redistribution and concentration of these elements both in the form of impurities and as a result of the redeposition of their own mineral phases. The variations in compositions of apatite, pyrochlore and monazite from different horizons of laterite profile were chosen as a proxy for the REE distribution in the supergene zone. Fluorapatite is gradually being replaced by hydroxyl-fluorapatite and carbonate-hydroxyl-fluorapatite, as the degree of weathering of primary carbonatites increases. Pyrochlore-Ca-Na-F is being replaced by the (BaSr)-variety (with Ce and Pb) during the same processes. Monazite changes from (Ce)-dominated to (La)-dominated. This is influenced by the oxidation factor, the consequence of which is also the formation of cerianite in the upper horizon. The study of the mineral and geochemical features of such an object as Chuktukon provides an improved understanding of the patterns of redistribution of the main and ore components of carbonatites in the supergene zone and can be useful in the study of other supergene deposits and delineation of dispersion halos of ore components.

Enhancing Stability of Surface Au under Oxidizing Conditions through Reduced Bulk Au Content.

Contrary to the common assumption that a higher bulk content of precious metals facilitates the preservation of more surface noble metal by serving as a reservoir for surface enrichment, we demonstrate that a lower bulk content of Au results in a more stable arrangement of Au atoms at the surface of Cu-Au nanoparticles when exposed to an O2 atmosphere. Using ambient pressure X-ray photoelectron spectroscopy, we investigate the surface segregation and oxidation behavior of Cu-Au nanoparticles across various compositions. Our results reveal that in Au-rich nanoparticles exposed to an H2 atmosphere, surface segregation prompts the formation of a continuous Au-enriched shell, which subsequently oxidizes into a complete CuOx shell upon transitioning to an O2 atmosphere. Conversely, in Au-poor nanoparticles during H2 treatment, segregation results in the emergence of Au clusters embedded within the surface layer, persisting upon exposure to O2. This unexpected phenomenon shows that reducing the bulk content of precious metals can enhance the surface stability of noble atoms under oxidizing conditions, as further demonstrated by comparing the catalytic performance of Cu-Au nanoparticles with varying Au bulk contents in CO oxidation.

Interlaboratory Evaluation of Bretziella fagacearum Molecular Detection Assays to Guide the eDNA Monitoring of Oak Wilt Disease

ABSTRACTOak wilt disease, caused by the fungus Bretziella fagacearum, can kill mature red oaks within months of infection, severely affecting biodiversity, landscapes, and industries. The disease, originally only present in the United States, was officially reported for the first time in Canada in June 2023. The aim of this study was to suggest a standardized assay and sample processing method to optimize oak wilt detection both in infection centers and ahead of the disease front. Two previously published molecular assays, a Nested PCR and a TaqMan qPCR, were compared to detect B. fagacearum in a variety of samples in a ring trial across five laboratories. Sample types investigated included eDNA from trapped insect vectors (sorted insects and bulk content from traps), infested and healthy oak wood chips, and B. fagacearum conidia dilutions. Results demonstrated that both Nested and TaqMan assays can be used for molecular confirmation of oak wilt, and results are reproducible across different labs. There is a general agreement between both detection assays when testing true‐positive and true‐negative samples. Both methods demonstrated overall good accuracy. The TaqMan assay was more sensitive and detected lower amounts of DNA target. Both tests were 100% specific to oak wood samples, which was the best sample type to use for detection. In general, samples with high Cts were more prompted to yield false negative Nested results. Detecting oak wilt from bulk insect samples was by far more rapid than sorted sap beetles, but resulted in lower detection signals, especially with the Nested assay. The time‐period when the insect traps were set up also had considerable influence on detection results. We hope this study helps to formulate guidelines in oak wilt detection and biosurveillance management.

Grain boundary segregation for the Fe-P system: Insights from atomistic modeling and Bayesian inference

In this work we re-assess experimental data for grain boundary (GB) segregation of P in bcc Fe with thermodynamic and statistical methods. The data are based on Auger-Electron-Spectroscopy (AES) measurements which have provided P GB concentrations for various bulk contents and temperatures for ferrite. While in the previous investigations of this system a single-site McLean equation was used to extract segregation enthalpy and entropy, we employ multi-site segregation models as suggested by atomistic simulations. We use a recently introduced methodology based on inter-atomic potentials to calculate the segregation energy spectrum, as well as vibrational entropy and solute-solute interactions of P in polycrystalline Fe, thereby obtaining a three-dimensional distribution of energy, entropy and interactions. Using this trivariate distribution we predict P GB concentrations and compare them to the experimental measurements. Furthermore, we calibrate the parameters of physical models of increasing complexity to the experimental data with an inverse modeling approach based on Bayesian inference. While it is not possible to seamlessly link the results from AES to atomistic modeling, our investigation provides significant new insights for thermodynamic modeling of GB segregation. The vibrational entropy deduced from experiment differs from physics based atomistic simulations even when taking the spectral nature of energy, entropy and interactions into account. However, the correlations of the quantities are in good agreement when considering the trivariate model. Our investigation highlights the need for new and more accurate experimental datasets of GB segregation.

Towards detailed combustor wall kinetics: An experimental and kinetic modeling study of hydrogen oxidation on Inconel

Gas-phase hydrogen combustion is ubiquitous in industrial processes, and the associated surface kinetics on heat-resistant alloys plays a crucial role in designing efficient low-carbon technologies. We conducted new temperature programmed reduction experiments to determine the reducibility of materials following an oxidation cycle. These experiments were modeled using a thermoconsistent multi-site microkinetic model for H2 heterogeneous oxidation on Inconels, which was validated against literature experiments. This competitive adsorption model considers iron bulk content, hydrogen spillover and subsurface oxygen migration on hydrogen surface oxidation kinetics. New X-ray diffraction experiments confirmed the postulated crystallographic structures in the Inconel samples, suggesting their presence on the surface scale. The phenomenological model was coupled with several state-of-the-art gas-phase oxidation mechanisms to assess gas/surface reactions interaction as a function of material and temperature. The results reveal a complex interaction in which surface removes H radicals from the gas-phase, while the Bradford (H2+OH) reaction converts OH into H2O, promoting water adsorption on Inconel. This interaction was found to give rise to gas-phase thermokinetic oscillations. The model predicts a non-monotonous effect of reactor area-to-volume ratio on reactivity and emphasizes the impact of Inconel composition on product selectivity. Overall, the multi-site model provides new insight into the contrasting reactivities among active sites, bridging the gap between material science and heterogeneous combustion modeling.

Broadening the Realm of Nanoporous Gold Catalysts: Preparation and Properties When Emanating from AuCu as Parent Alloy

AbstractNanoporous gold (npAu) attracted increasing attention over the last 20 years as a highly active and selective oxidation catalyst in particular at low temperatures. Previous research mainly focused on npAu that was fabricated by corrosive dealloying of AuAg parent alloys. Yet, the use of other binary alloys, such as AuCu, promises interesting variations of the catalytic properties, when considering that residual amounts of the less noble metal were shown to be co‐catalytically involved. Aiming at providing a platform for systematic studies in this direction for Cu, we not only dealt with strategies for a reliable and reproducible preparation of npAu(Cu) catalysts from AuCu, but also with their potential for CO oxidation in comparison to npAu(Ag). We were able to develop an approach based on thermally quenched Au0.3Cu0.7 alloys, providing distinct synthetic advantages as a starting material for the catalyst fabrication versus the thermodynamically more stable AuCu3 intermetallic compound. Using PCD (potentiostatically controlled dealloying), well‐defined pore structures with ligament diameters of ∼40 nm and variable residual Cu concentrations in the range between ∼0.6 at % and ∼1.2 at % could be straightforwardly obtained. After activating such catalysts at 150 °C, they reproducibly showed catalytic activity for aerobic CO oxidation in a broad temperature window between 40 °C and 250 °C. As opposed to npAu(Ag), the activity increased with decreasing residual Cu content, outperforming the former at temperatures above ∼60 °C not only with respect to CO2 formation rates but also with respect to thermal stability. Based on X‐ray photoelectron spectroscopic and transmission electron microscopic results, it was possible to conclude that Cu segregates to the surface and, with rising Cu bulk content, increasingly occurs in form of Cu2+ species at the surface. While the latter are expected to be catalytically inactive, Cu and Cu+ species are likely candidates for the activation of oxygen being not possible on pure Au.

Tailoring the Surface Enrichment of a Pt Catalyst in Ionic Liquid Solutions by Choice of the Solvent

AbstractThe so‐called buoy‐effect, that is, the targeted surface enrichment of a Pt catalyst dissolved in ionic liquids (ILs), is achieved by attaching perfluorinated alkyl chains to the ligand system, which drags the metal complex toward the interface. Using angle‐resolved X‐ray photoelectron spectroscopy, it is demonstrated how this surface enrichment can be tailored by variation of the solvent IL. In [CnC1Im][PF6] ILs (n = 2, 4, 8), the surface is fully saturated with the complex at 10%mol bulk content, while in [C4C1Im][Tf2N] only at 20%mol saturation is observed. At low catalyst concentrations of 1%mol, where saturation is not yet reached, the enrichment increases with decreasing length of the IL alkyl chain. As a general rule, the degree of surface enrichment decreases with the decrease in surface tension of the solvent IL, that is, in the order [C2C1Im][PF6] > [C4C1Im][PF6] > [C8C1Im][PF6] > [C4C1Im][Tf2N]. In ILs with very low surface tension, enrichment is even suppressed. These results reveal the surface tension of the solvent IL as rational parameter for tailoring the interfacial structure of IL‐based catalyst systems, such as supported ionic liquid phase (SILP) catalysis, where the nature of the IL/gas interface is expected to strongly influence the performance of the process.

Scallop shells as biosorbents for water remediation from heavy metals: Contributions and mechanism of shell components in the adsorption of cadmium from aqueous matrix

To ascertain their potential for heavy metal pollution remedy, we studied the adsorption mechanism of cadmium onto scallop shells and the interactions between the heavy metal and the shell matrix. Intact shells were used to investigate the uptake and diffusion of the metal contaminant onto the shell carbonatic layers, as well as to evaluate the distribution of major and trace elements in the matrix. LA-ICPMS measurements demonstrate that Cd is adsorbed on a very thin layer on the inner and outer surfaces of the shell. Structural and thermal analyses showed the presence of 9 wt.-% of a CdCO3 phase indicating that the adsorption is mainly a superficial process which involves different processes, including ion exchange of Ca by Cd. In addition, organic components of the shell could contribute to adsorption as highlighted by different metal uptake observed for shells with different colours. In particular, darker shells appeared to adsorb more contaminant than the white ones. The contribution of the organic shell components on the adsorption of heavy metals was also highlighted by the element bulk content which showed higher concentrations of different metals in the darker specimen. Raman spectroscopy allowed to identify the pigments as carotenoids, confirmed by XRD measurements which highlighted the presence of astaxanthin phases. The results presented here provide new insights into the Cd adsorption mechanism highlighting the important contribution given by the organic components present in the biogenic carbonate matrix. Furthermore, the high efficiency of Cd removal from water by scallop shells, supported by adsorption kinetic and isotherm studies, has been demonstrated.

Hawaiian Volcanic Ash, an Airborne Fomite for Nontuberculous Mycobacteria.

Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that can cause chronic lung disease. Within the U.S., Hawai'i shows the highest prevalence rates of NTM lung infections. Here, we investigated a potential role for active volcanism at the Kīlauea Volcano located on Hawai'i Island in promoting NTM growth and diversity. We recovered NTM that are known to cause lung disease from plumbing biofilms and soils collected from the Kīlauea environment. We also discovered viable Mycobacterium avium, Mycobacterium abscessus, and Mycobacterium intracellulare subsp. chimaera on volcanic ash collected during the 2018 Kīlauea eruption. Analysis of soil samples showed that NTM prevalence is positively associated with bulk content of phosphorus, sulfur, and total organic carbon. In growth assays, we showed that phosphorus utilization is essential for proliferation of Kīlauea-derived NTM, and demonstrate that NTM cultured with volcanic ash adhere to ash surfaces and remain viable. Ambient dust collected on O'ahu concurrent with the 2018 eruption contained abundant fresh volcanic glass, suggestive of inter-island ash transport. Phylogenomic analyses using whole genome sequencing revealed that Kīlauea-derived NTM are genetically similar to respiratory isolates identified on other Hawaiian Islands. Consequently, we posit that volcanic eruptions could redistribute environmental microorganisms over large scales. While additional studies are needed to confirm a direct role of ash in NTM dispersal, our results suggest that volcanic particulates harbor and can redistribute NTM and should therefore be studied as a fomite for these burgeoning, environmentally acquired respiratory infections.

Effects of TiO2 ultraviolet filter and sunscreens on coastal dune plant performance and competitive interactions

Ultraviolet filters (UVFs) added to sunscreens (SS) are emerging contaminants in marine environments due to their adverse effects on organisms and ecosystems. UVFs have also been detected in beach-dune systems, but their influence on resident organisms has not been explored yet. Native plants are fundamental components of coastal dunes, and these ecologically/economically important systems are currently among the most threatened globally. Thus, understanding whether UVFs may act as threats to dune plants is crucial. This field study evaluated and compared the effects of titanium dioxide nanoparticles (nTiO2), one of the inorganic UVFs most commonly added to sunscreens, and those of a commercial sunscreen product containing it (SS-nTiO2) on the performance of adult dune plants of a native (Thinopyrum junceum) and a non-native invasive species (Carpobrotus sp. pl.) and their competitive interactions at environmentally realistic concentrations. The effects of nTiO2, SS-nTiO2 and of a sunscreen product containing just organic UVFs (SS-OF) on early life stages of T. junceum were also examined. Ti bulk content in sand and plants at the study site ranged from 970 to 1069 mg kg−1 and from 2 to 7.9 mg kg−1, respectively. Thinopyrum junceum adult plants periodically exposed during the summer season to seawater contaminated by SS-nTiO2 produced less biomass than un-exposed plants and nTiO2 exposed plants. nTiO2 and SS-nTiO2 reduced the capacity of T. junceum to control the spread of Carpobrotus. Both SS-nTiO2 and SS-OF reduced seedling emergence in T. junceum whereas nTiO2 did not. These results demonstrated that the periodical exposures of native dune plants to sunscreens could reduce their establishment success and growth and favor invasive plant spread potentially resulting in community structure changes. They also emphasize the need to assess the phytotoxicity not only of single UVFs but especially that of complete sunscreen products to design more eco-friendly formulations in the future.

GEMAS: Chemical weathering of silicate parent materials revealed by agricultural soil of Europe

The chemical composition of soil represents to a large extent the primary mineralogy and geochemistry of the source bedrock, the effects of pre- and post-depositional weathering and element mobility, either by leaching or mineral sorting with the addition of secondary products such as clays. Agricultural soil in Europe (0–20 cm, 33 countries, 5.6 million km2) was sampled during the continental-scale soil mapping project (GEochemical Mapping of Agricultural and grazing land Soil - GEMAS). Total element concentrations were determined by wavelength dispersive X-ray fluorescence spectrometry. Bulk content of major elements (SiO2, TiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, P2O5) in soil has been used to calculate weathering indices such as chemical index of alteration (CIA), reductive and oxidative mafic indices of alteration (MIA), the change in mass balance (τ calculation relative to immobile Nb) for soil derived from silicate bedrocks (granite, gneiss and schist) at the European continental-scale, which are useful tools for evaluating chemical weathering trends.The greatest variation of CIA values is exhibited by soil derived from granite, followed by soil derived from schist. The CIA results show clearly that Ca and Na are removed from agricultural soil (0–20 cm) during soil development. Geographical distribution of weathering indices shows that weak chemical weathering of agricultural soil samples, sourced from gneissic and granitic bedrock, occurs in the Fennoscandian Shield; intermediate chemical weathering in granite, schist and gneiss occurring in the Iberian Peninsula and France, and intense chemical weathering in schist sourced agricultural soil occurring in areas with intense rainfall and moderate temperature (Wales, England, Ireland and western Iberia). In addition, values of CIA and MIA, higher than those for standard rock compositions, suggest more active enrichment/depletion processes during soil formation and subsequent soil weathering/maturation.The range of the elemental mass transfer coefficient τ is wide for agricultural soil derived from gneiss and granite, and narrow for agricultural soil sourced from schist parent rocks. The weathering behaviour of chemical elements, assessed by using the τ mass transport model, suggests an order of susceptibility of K ≈ Na > Al > Fe > Ca > Mg > Ti.Weathering indices and gain-loss mass transfer coefficients, tested on agricultural soil samples, provide an insight to the weathering processes affecting the silicate parent rocks and their impact on soil development at the European scale. This can have further implications for evaluation of soil nutritional conditions and mitigating of soil erosion and deprivation.

Evaluation of As-Received Green Liquor Dregs and Biomass Ash Residues from a Pulp and Paper Industry as Raw Materials for Geopolymers

This study aimed to investigate the impact of as-received biomass fly ashes (BFA) and green liquor dregs obtained from a pulp and paper plant in Brazil as substitutes for metakaolin in geopolymeric formulations. The properties of this type of waste material vary widely between different industrial plants. This study refrains from subjecting the waste materials to any form of pretreatment, taking into account their organic matter and particle size heterogeneity, requiring extensive characterization to evaluate their influence on the compressive strength, apparent open porosity, and water absorption of the geopolymeric samples. The objective was to assess their potential for upcycling purposes as an alternative to energy-intensive materials, such as ordinary Portland cement (OPC) and advanced ceramics. This potential arises from the ability of alkali-activated materials (AAM) to undergo curing at ambient temperatures, coupled with the possibility of compositions primarily derived from waste materials. To improve the sustainability of the products, the amorphous content of the raw material, which is more reactive than crystalline phases, was quantified and used as the base for mixture ratios. This approach aimed to reduce the requirement for alkaline activators, which have significant environmental impacts, while also increasing the waste content in the formulation. The incorporation of waste materials into the geopolymer matrix generally led to a reduction in the compressive strength compared to the benchmark metakaolin sample (19.4 MPa) but did not present a trend. The dregs led to values of 4.1 MPa at 25 wt% and 7.1 MPa at 50 wt%, a behavior that is somewhat counterintuitive, and BFA at 10 wt% presented 5.7 MPa. Nevertheless, the apparent open porosity remained at high levels for all the samples, close to 50%, and the compressive strength of most of them was over the values obtained for the metakaolin-only samples with mixture ratios calculated from the total composition instead of the amorphous composition. The decrease in strength and the increase in porosity were attributed to the specific characteristics of the waste materials, such as their high crystallinity, presence of organic matter, heterogeneous particle composition, and size. Overall, this study provides insight into the variations in geopolymerization based on the bulk and amorphous content of the aluminosilicate sources and how the characteristics of the waste materials influence the geopolymer matrix. It also highlights how calculating mixture ratios based on the amorphous composition improves the possibility of waste valorization through alkali activation. Additionally, it suggests that BFA and dregs might be effectively utilized in applications other than OPC substitution, such as adsorption, filtration, and catalysis.

Interpretation of uniaxial, confined compression test data for agricultural topsoils

Traditionally, soil strength is estimated from uniaxial, confined compression tests by procedures adopted from classical soil mechanics. The heterogeneity of agricultural topsoil calls for an alternative approach. Undisturbed soil cores were collected in the plough layer of 14 soils in arable agriculture. Soil texture ranged from coarse sandy to silty loam soils with a maximum of 20% clay. The samples were drained to either of six matric potentials in the range from − 30 to − 300 hPa. Uniaxial, confined compression was applied to ∼800 kPa with strain-controlled stress application (1 mm min−1). Measured strain was fitted to stress by the Morgan-Mercer-Flodin (MMF) model. The model fitted data remarkably well for all samples. Three fitting parameters of the model reflected physical characteristics of soil reaction to stress. The estimates of soil compressibility calculated from the model at 10 kPa (C10) correlated closely and linearly to the Cs index considered to reflect elastic deformation in classical studies of soil compression tests. Soil bulk density and content of soil organic matter decreased C10 as well as compressibility at 100 (C100) and 400 kPa (C400). A complex pattern in the effects of soil texture and soil moisture on compressibility was revealed. The pattern in strain-stress data is interpreted as a reflection of a gradual transition from elastic to plastic deformation of the mixture of structural units. The MMF model is suggested for interpretation of strain-stress data from uniaxial, confined compression tests. This implies use of stress in a linear scale.

Effects of Road Dust Particle Size on Mineralogy, Chemical Bulk Content, Pollution and Health Risk Analyses.

Because of the rising environmental and health concerns associated with atmospheric pollution caused by potentially toxic elements (PTEs), several road dust studies have been performed across the world in recent decades. This paper illustrates the effects of particle size on the PTE contents, mineralogical composition, environmental pollution and health risk assessments in road dust from Barcelona (Spain). The samples were sieved into five size fractions ranging from <45 to 500-800 µm. Although the major mineral contents (tectosilicates, phyllosilicates, and carbonates) were profuse in all fractions, the identified inhalable PTE particles (e.g., Fe, Cr, Cu, Zn, Ni, and REE), with size < 10 µm, were more pervasive in the finest fraction (<45 μm). This is consistent with the concentrations measured: the finest fractions were richer in PTEs than the coarser ones, resulting in a direct correlation with the enrichment factor (EFx), geo-accumulation (Igeo), and non-carcinogenic (HI) and carcinogenic (CRI) values. Igeo and EFx values can be appropriate tracers for some common elements (e.g., Zn, Sb, Sn, Cu, and Cr), but they do not seem adequate for anthropogenic particles accumulated at concentrations similar to the geogenic background. Overall, the HI and CRI values obtained in Barcelona were acceptable, reflecting no serious health impacts in the study area, except for Cr. Our results suggest that fine dust particles are a more suitable fraction to conduct pollution and health risk assessments than coarser ones, although the EFx, Igeo, HI, and CRI threshold values should be redefined in the future to include all emergent pollutants as well. In summary, monitoring programs should include at least the road dust evaluation of <45 µm particles, which can be performed with a simple sieving method, which is both time- and cost-effective.

Biogeochemical State of Salinized Irrigated Soils of Central Fergana (Uzbekistan, Central Asia)

The Central Fergana region is one of the overpopulated regions of Central Asia, which includes parts of Uzbekistan, Kyrgyzstan, and Tajikistan. Here, in the dry subtropical climate are the most ancient, irrigated oases used for agriculture. Fergana valley is the key to the food security of the region as a whole. The article provides information on diversity and chemical composition of newly developed, new and old-irrigated Calcisols soils formed on alluvial and alluvial–prolluvial sediments. Soils are poor with organic matter (0.37–0.81% of organic carbon), with high nitrogen content (C/N ratio is 4.92–5.79), and with neutral (7.01–7.30) pH values. Data on the content and the ratio of the key components of soil salinity (Na2CO3, Ca(HCO3)2, CaSO4, MgSO4, Na2SO4, NaCl) and the bulk content of salts in soils under different irrigation regimes are presented. It was shown that Na2CO3 concentration is minimal in all the soils, and this salt presents only in ground waters (0.100–0.135 g L−1). Newly irrigated soils are characterized by higher content of salts than old irrigated soils. All the soils investigated are characterized by increasing salinity rate within the soil depth with the highest content of all salts in ground waters. This chloride–sulfate type of salinization is most pronounced in all the soils studied. Gypsum content in agricultural soils results in limited water and nutrient retention and the potential for dissolution, primarily in response to irrigation. The soils of the Fergana Valley are also subjected to polychemical pollution, so the content of trace elements in them was studied. Irrigated meadow-takyr and meadow-saz soils show low levels of environmental hazard, but irrigation results in accumulation of such trace elements as nickel (30 mg kg−1), arsenic (11.75 mg kg−1), bromine (5.00 mg kg−1), antimony (1.48 mg kg−1), cesium (5.00 mg kg−1), and hafnium (2.97 mg kg−1). Irrigation also affects the soil texture and thus increases fine particle percentages in the superficial soil horizons. Thus, the complex chemical characteristics of salinized soils are presented for numerous irrigated landscapes of the region.

Rumen Biogeographical Regions and Microbiome Variation.

The rumen is a complex organ that is critical for its host to convert low-quality feedstuffs into energy. The conversion of lignocellulosic biomass to volatile fatty acids and other end products is primarily driven by the rumen microbiome and its interaction with the host. Importantly, the rumen is demarcated into five distinct rumen sacs as a result of anatomical structure, resulting in variable physiology among the sacs. However, rumen nutritional and microbiome studies have historically focused on the bulk content or fluids sampled from single regions within the rumen. Examining the rumen microbiome from only one or two biogeographical regions is likely not sufficient to provide a comprehensive analysis of the rumen microbiome and its fermentative capacity. Rumen biogeography, digesta fraction, and microbial rumen-tissue association all impact the diversity and function of the entirety of the rumen microbiome. Therefore, this review discusses the importance of the rumen biographical regions and their contribution to microbiome variation.

Pyrolysis Atmospheres and Temperatures Co-Mediated Spectral Variations of Biochar-Derived Dissolved Organic Carbon: Quantitative Prediction and Self-Organizing Maps Analysis.

Biochar-derived dissolved organic carbon (BDOC), as a highly activated carbonaceous fraction of biochar, significantly affects the environmental effect of biochar. This study systematically investigated the differences in the properties of BDOC produced at 300-750 °C in three atmosphere types (including N2 and CO2 flows and air limitation) as well as their quantitative relationship with biochar properties. The results showed that BDOC in biochar pyrolyzed in air limitation (0.19-2.88 mg/g) was more than that pyrolyzed in N2 (0.06-1.63 mg/g) and CO2 flows (0.07-1.74 mg/g) at 450-750 °C. The aliphaticity, humification, molecular weight, and polarity of BDOC strongly depended on the atmosphere types as well as the pyrolysis temperatures. BDOC produced in air limitation contained more humic-like substances (0.65-0.89) and less fulvic-like substances (0.11-0.35) than that produced in N2 and CO2 flows. The multiple linear regression of the exponential form of biochar properties (H and O contents, H/C and (O+N)/C) could be used to quantitatively predict the bulk content and organic component contents of BDOC. Additionally, self-organizing maps could effectively visualize the categories of fluorescence intensity and components of BDOC from different pyrolysis atmospheres and temperatures. This study highlights that pyrolysis atmosphere types are a crucial factor controlling the BDOC properties, and some characteristics of BDOC can be quantitatively evaluated based on the properties of biochar.

Origin of enhanced passivity of Cr–Fe–Co–Ni–Mo multi-principal element alloy surfaces

Surface analysis by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry was applied to investigate the origin of the enhanced surface passivity and resistance to a chloride-induced breakdown provided by the protective ultrathin oxide films formed on Cr–Fe–Co–Ni–Mo single-phase fcc multi-principal element alloys. A bilayer structure of the oxide films is observed with the inner barrier layer mostly constituted of Cr(III) oxide and the outer layer enriched in Cr(III) hydroxides and Mo(IV,VI) oxides. The Mo(VI) and Mo(IV) species are mainly located in the outer and inner parts of the outer layer, respectively. Anodic passivation promotes mainly the growth of the inner layer on the alloy of higher Cr bulk content and the outer layer on the alloy of higher Mo bulk content. Passivation also promotes the enrichment of Cr(III) hydroxide and Mo(IV) and Mo(VI) oxides in the outer layer. Depth distribution analysis suggests that the ultra-thin protective inner barrier contains Cr(III)-depleted heterogeneities acting as weak sites for chloride attack, which are reinforced by the Mo(IV) oxide species concentrated close to the inner barrier layer. This elemental distribution provides an explanation for the reinforcement of the resistance to localized corrosion observed on these Cr–Fe–Co–Ni–Mo alloys.