Residual Mineral Research Articles

Cysteine-Facilitated Cr(VI) reduction by Fe(II/III)-bearing phyllosilicates: Enhancement from In-Situ Fe(II) generation

Structural Fe in phyllosilicates represents a crucial and potentially renewable reservoir of electron equivalents for contaminants reduction in aquatic and soil systems. However, it remains unclear how in-situ modification of Fe redox states within Fe-bearing phyllosilicates, induced by electron shuttles such as naturally occurring organics, influences the fate of contaminants. Herein, this study investigated the processes and mechanism of Cr(VI) reduction on two typical Fe(II/III)-bearing phyllosilicates, biotite and chlorite, in the presence of cysteine (Cys) at circumneutral pH. The experimental results demonstrated that Cys markedly enhanced the rate and extent of Cr(VI) reduction by biotite/chlorite, likely because of the formation of Cr(V)-organic complexes and consequent electron transfer from Cys to Cr(V). The concomitant production of non-structural Fe(II) (including aqueous Fe(II), surface bound Fe(II), and Cys-Fe(II) complex) cascaded transferring electrons from Cys to surface Fe(III), which further contributed to Cr(VI) reduction. Notably, structural Fe(II) in phyllosilicates also facilitated Cr(VI) reduction by mediating electron transfer from Cys to structural Fe(III) and then to edge-sorbed Cr(VI). 57Fe Mössbauer analysis revealed that cis-coordinated Fe(II) in biotite and chlorite exhibits higher reductivity compared to trans-coordinated Fe(II). The Cr end-products were insoluble Cr(III)-organic complex and sub-nanometer Cr2O3/Cr(OH)3, associated with residual minerals as micro-aggregates. These findings highlight the significance of in-situ produced Fe(II) from Fe(II/III)-bearing phyllosilicates in the cycling of redox-sensitive contaminants in the environment.

Low N2O emissions induced by root-derived residues compared to aboveground residues of red clover or grass mixed into soil

The default The Intergovernmental Panel on Climate Change (IPCC) guidelines assume a constant N2O emission factor (EFN2O) for both belowground crop residues (BGR) and aboveground residues (AGR), and that ∼70 % of total N2O emissions following renewal of temporary grasslands come from BGR. However, empirical evidence is lacking, which motivated this study. BGR-free and BGR-rich clay loam collected in grass or red clover leys were incubated alone or mixed with AGR and different doses of nitrate over 107 days. The average EFN2O of BGR was around 18 % of that of AGR, and remained low even when soil nitrate concentration was very high, whereas EFN2O of AGR varied largely and rocketed even with a small increase in soil nitrate. The decomposition of the carbon present in crop residues was critical for N2O emissions. Lower EFN2O of BGR relative to AGR were related to slower C decomposition, which was not predicted by the biochemical characteristics. It is also likely that BGR were less conducive than AGR to develop into hotspots for N2O emission because of the roots’ finer distribution and closer contact with soil particles. Differences in EFN2O among AGR were mostly linked to the availability of N, either derived from residue mineralization or present in the soil. In conclusion, N2O accountings based on present IPCC default methodology likely overestimate the contribution by crops’ BGR.

Impact of winter coverage crops and nitrogen fertilization on soil respiration and nitrogen mineralization in no-tillage systems

Microbiological activity in soil is crucially important to maintaining soil quality. Soil is sensitive to management practices, and microbiological activity plays a crucial role in processes like transforming organic N into inorganic fractions. The objective of this study was to assess how winter coverage crop residues influence soil respiratory activity and N mineralization during successive corn crop developments under a no-tillage regime. We employed a randomized block experimental design with subdivided plots and three replications. The main plots comprised various coverage crops (Black Oats, Ryegrass, Rye, White Lupin, Common vetch, Turnip, consortia of Oats + Vetch and Oats + Vetch + Turnip, while subplots received doses of N-mineral (0 and 180 kg ha-1) during the corn growth stage. We evaluated the respiratory activity of microorganisms and levels of inorganic N in the soil throughout the corn crop cycle. The consortia of coverage crops exhibited distinct responses in respiratory rates, with Oats + Vetch having superior results compared to Oats + Vetch + Turnip. We observed positive responses in nitric N (N-NO3-) due to the mineralization of common vetch residues within the first fifteen Days After Sowing (DAS). However, N-mineral doses from nitrogen fertilization during the corn coverage age phase did not alter the respiratory of the microorganisms nor did it alter the concentrations of N-NH4+ in the soil. Mineral fertilization resulted in the immediate availability of N in the form of N-NO3-.

Physical and chemical characterization of chitin and chitosan extracted under different treatments from black soldier fly

The shell of Hermetia illucens L. contains considerable amounts of chitin, which has various biological activities. So far, few studies have focused on chitin of Hermetia illucens L. as a source of chitosan and oligosaccharides. There is great potential for utilizing Hermetia illucens L. chitin to produce chitosan films in biomaterials. We studied different extraction conditions for chitin and extracted it from black soldier fly (BSF) (Hermetia illucens L.). Three processing steps were adopted: (1) demineralization, (2) deproteinization, and (3) decolorization. The chemical components (moisture, ash, protein, fat, residual protein, and residual mineral contents) and physicochemical characteristics of the chitin and chitosan extracted under these three conditions were determined. In addition, Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the extracted chitin and commercial samples, and the results showed that demineralization–deproteinization–decolorization treatments could achieve the highest chitin yield (7.18 ± 0.11 %), chitosan yield (64.22 ± 0.79 %), and the best purity (residual protein 0.56 ± 0.01 % and residual ash 0.58 ± 0.04 %), making it the best treatment method. Using this method, the residues produced from farmed BSF can be recycled and used as a new source of chitin.

Enhanced mineralization of pharmaceutical residues at circumneutral pH by heterogeneous electro-Fenton-like process with Cu/C catalyst

Conventional electro-Fenton (EF) process at acidic pH ∼3 is recognized as a highly effective strategy to degrade organic pollutants; however, homogeneous metal catalysts cannot be employed in more alkaline media. To overcome this limitation, pyrolytic derivatives from metal-organic frameworks (MOFs) have emerged as promising heterogeneous catalysts. Cu-based MOFs were prepared using trimesic acid as the organic ligand and different pyrolysis conditions, yielding a set of nano-Cu/C catalysts that were analyzed by conventional methods. Among them, XPS revealed the surface of the Cu/C-A2-Ar/H2 catalyst was slightly oxidized to Cu(I) and, combined with XRD and HRTEM data, it can be concluded that the catalyst presents a core-shell structure where metallic copper is embedded in a carbon layer. The antihistamine diphenhydramine (DPH), spiked into either synthetic Na2SO4 solutions or actual urban wastewater, was treated in an undivided electrolytic cell equipped with a DSA-Cl2 anode and a commercial air-diffusion cathode able to electrogenerate H2O2. Using Cu/C as suspended catalyst, DPH was completely degraded in both media at pH 6–8, outperforming the EF process with Fe2+ catalyst at pH 3 in terms of degradation rate and mineralization degree thanks to the absence of refractory Fe(III)-carboxylate complexes that typically decelerate the TOC abatement. From the by-products detected by GC/MS, a reaction sequence for DPH mineralization is proposed.

Physical and numerical simulation of heat and mass transfer in the furnace of a thermogravimetric analyzer

A numerical study of the processes of heat and mass transfer in the furnace of a thermogravimetric analyzer was carried out, aimed at improving the accuracy of determining the kinetic characteristics of samples during their thermal transformations in different media. Validation of the model and prognostic estimates were carried out in relation to specially conducted thermogravimetric studies of the conversion of fossil and renewable carbon-containing raw materials in successive processes of decarbonization (combustion) and carbonation (mineralization of ash residue). The application of the study results allows to calculate the actual concentrations of the reagent over the sample uncontrolled by the device during pulsed switching of media and the actual temperatures of the sample during its thermochemical transformations.

Cyclicity of katatectic layers in anhydrite caprocks, U.S. Gulf Coastal Region

ABSTRACT An anhydrite caprock overlies 65% of the 329 onshore salt stocks of the U.S. Gulf Coastal Region, south-central U.S. The caprock consists of a succession of katatectic (downward-building) layers of anhydrite (typically 1–4 cm thick) each overlain by an upper, black pyrite lamina (∼ 0.1 mm thick). The older (upper) katatectic layers are usually highly deformed. During four stages, these fundamental layers formed at the crest of shallow (< 1,200 m) salt stocks. Repetition of sets of the stages resulted in the cyclicity. The closed stage A flush, nearly planar contact separated mature anhydrite caprock from an underlying salt-stock crest. As the diapir elevated by a few mm/yr, it arched the caprock; it also opened conduits at the stock’s uppermost anhydrite sheath, allowing NaCl-undersaturated water from outside the diapir to contact the salt stock. The open-dynamic stage: Along the perimeter of the uppermost salt stock, a narrow, annular halite cave advanced inward and upward directly below the slightly convex base of the anhydrite caprock. The most NaCl-aggressive water rose by free convection to the highest elevations and dissolved halite. The dense, solute-enhanced water then reversed direction and, again, by free convection, flowed past the stock’s margin into country rock; NaCl-undersaturated water replaced the departing brine. A water-filled, commonly ring-shaped, planar cave up to several meters high expanded over the stock’s crest. Sparse physical supports, buoyancy, arched caprock, and high artesian water pressure prevented the cave’s collapse. The cave’s halite floor dissolved vertically downward faster than it moved diapirically upward. As the crestal halite dissolved, a small amount of residual pyrite and, typically, a layer up to ∼ 10 cm thick of residual anhydrite (generally 3–8 wt % of the stocks) accumulated on the cave floor. The open-static stage: The persistent “attack” of halite highs by the NaCl-undersaturated water eventually caused the slope of the cave’s floor to approach horizontality. The density-driven flow slowed markedly, and a static cover of NaCl-saturated brine thwarted the dissolution of the halite floor. The downward movement of the cave’s floor reversed, and it moved slowly upward via diapirism. Concurrently, an anhydrite sheath evolved around the uppermost stock. The accretionary stage The cave closed in a few thousand years, and active diapirism underplated the admixed residual minerals onto the base of the caprock. The uppermost, now compact, residual anhydrite dissolved in the high-pressure environment, leaving the discrete, topmost, thin, black pyrite lamina. With the accretion of the residual minerals, a katatectic layer formed at the base of a succession of such layers. The closed stage recurred, and a new katatectic cycle began forming. Variations of the four genetic stages probably occurred during the formation of anhydrite caprocks in other worldwide salt-dome provinces, but because of insufficient data, they are usually unrecognizable.

Heavy magnesium isotopic signatures in arc lavas may be attributed to dehydration of subducting hydrated mantle

Fluids released from subducting slabs profoundly affect mantle composition, rock melting points, and arc magma generation. However, identifying fluid sources (sediments, crust, or mantle) and their ascent paths remains challenging. Magnesium isotopes are potential tracers for subduction-related fluids, though their behavior during hydrous peridotite dehydration remains unclear. Here we determined the equilibrium magnesium isotope fractionation factors between aqueous fluids and hydrous peridotitic minerals using first-principles calculations. Aqueous fluids prefer heavy magnesium isotopes relative to mantle silicate minerals, indicating that fluids released during hydrous peridotite dehydration are enriched in heavy magnesium isotopes relative to the residual minerals. Our simulations proposed that magnesium isotope variations in arc lavas from different subduction zones could be attributed to different dehydration reactions influenced by subduction zone thermal structures. This study highlights the potential of magnesium isotopes for tracing fluids originating from subducting hydrated mantle, providing insights into the thermal structure of various subduction zones.

Role of minerals in regulating the mineralization of cover crop residue and native organic matter and the community and necromass of microbes in flooded paddy soils

Role of minerals in regulating the mineralization of cover crop residue and native organic matter and the community and necromass of microbes in flooded paddy soils

Adsorption Efficiency of Cadmium (II) by Different Alkali-Activated Materials.

The objective of this study was to demonstrate the potential utilization of fly ash (FA), wood ash (WA), and metakaolin (MK) in developing new alkali-activated materials (AAMs) for the removal of cadmium ions from waste water. The synthesis of AAMs involved the dissolution of solid precursors, FA, WA, and MK, by a liquid activator (Na2SiO3 and NaOH). In concentrated solutions of the activator, the formation of an aluminosilicate gel structure occurred. DRIFT spectroscopy of the AAMs indicated main vibration bands between 1036 cm-1 and 996 cm-1, corresponding to Si-O-Si/Si-O-Al bands. Shifting vibration bands were seen at 1028 cm-1 to 1021 cm-1, indicating that the Si-O-Si/Si-O-Al bond is elongating, and the bond angle is decreasing. Based on the X-ray diffraction results, alkali-activated samples consist of an amorphous phase and residual mineral phases. The characteristic "hump" of an amorphous phase in the range from 20 to 40° 2θ was observed in FA and in all AWAFA samples. By the XRD patterns of the AAMs obtained by the activation of a solid three-component system, a new crystalline phase, gehlenite, was identified. The efficiency of AAMs in removing cadmium ions from aqueous solutions was tested under various conditions. The highest values of adsorption capacity, 64.76 mg/g (AWAFA6), 67.02 mg/g (AWAFAMK6), and 72.84 mg/g mg/g (AWAMK6), were obtained for materials activated with a 6 M NaOH solution in the alkali activator. The Langmuir adsorption isotherm and pseudo-second kinetic order provided the best fit for all investigated AAMs.

Unraveling Parent Rock and Mineral Influences in Tropical Weathering Profiles: REE, Nd and Sr Isotopic Geochemistry

This study aims to investigate the effects of parent rock and minerals on lateritic weathering. The study presents X-ray diffraction (XRD), whole-rock geochemistry, and Nd-Sr isotopic data for examining two profiles, 10 and 12 m thick, respectively, that illustrate the regional tropical weathering status in the Midwest of Brazil. The profiles, developed from metasedimentary and sedimentary rocks, are constituted by saprolite, mottled horizon, lateritic duricrust, and oxisol. Across the profiles, the minerals controlling the weathering geochemistry are muscovite, microcline, quartz, kaolinite, hematite, goethite, and gibbsite. Red and yellow zones in the saprolite and mottled horizon as well as the lateritic duricrust with breccia/fragmental, pisolitic, and oolitic textures make profile 1 more complex. In contrast, profile 2 has an oxisol that mantles the homogeneous vermiform lateritic duricrust. Fe2O3, accumulated during surface weathering, is a potent element in the geochemical profile control since it forms the harder goethite to hematite lateritic duricrust, bearing most of the trace elements (As, Cu, Cs, Pb, Sc, Sr, Th, U, V, and Zn) with similar ionic radii and electrovalence. The LREE have affinity for the elements of the Fe2O3 group of the lateritic duricrust. On the other hand, the K2O group together with Zr and TiO2 e in the phyllite, saprolite, and mottled horizon of profile 1, are associated with the HREE. Additionally, in profile 2, the HREE are mostly associated with the Al2O3 group and the residual minerals in the oxisol. The indication that REE is associated with phosphates, zircon, rutile/anatase, cereanite, and muscovite/illite, which have variable weathering behavior, caused the REE fractionation to occur across and between the profiles. Despite the REE fractionation, the ƐNd(0) values along the profiles consistently maintain the signature of the parent rock. Muscovite and microcline weathering, in profiles 1 and 2, respectively, control the decrease in 87Sr/86Sr signatures of both profiles and the distinct radiogenic ratios. The development of lateritic duricrust in both profiles indicates a similar weathering intensity, although the gibbsite–kaolinite predominance in the oxisol of profile 2 highlights a geochemical reorganization under humid conditions, as well as near-intense soluble silica leaching.

Restoration of soil fertility and improvement of phytosanitary condition of soil in short rotation of crops in Polissia of Ukraine

With the intensification of agricultural land use and changes in natural conditions, soil quality in Ukraine is deteriorating, with a decrease in humus content, the average annual loss of which is about 0.6 t/ha. Therefore, its reproduction is now becoming increasingly important through the use of organic raw materials and the introduction of legumes into the crop rotation, which leads to a partial replacement of nitrogen from mineral fertilisers with biological nitrogen. The purpose of this study was to find ways to provide the topsoil with organic residues, develop soil microflora, and improve the activity of nitrogen-fixing bacteria in a short grain legume crop rotation. The study was conducted in 2019-2023 using the following methods: visual – to determine the stages of organogenesis; field – to determine the interaction of abiotic factors; physiological – to determine the symbiotic fixation of atmospheric nitrogen. It was found that due to mineralisation of organic residues of legume crop rotation, the amount of macro- and microelements in the soil layers 0-10 cm, 10-20 cm, and 20-30 cm increased by 45.1-46.9-43.1 mg/kg, respectively. It was found that saturation of short crop rotation by 50% with legumes, straw residues, and green manure contributed to the reduction of pathogenic microorganisms and the growth of suppressive ones. It was found that in a short rotation of crops, 10.3 t/ha of organic matter in the form of stubble and root residues, straw and green manure enters the soil, which contributed to the cultivation of environmentally friendly agricultural products with the restoration of soil fertility. The biological activity of the soil during the growing season in the layer of 10-20 cm reached 47.4%, and the content of alkaline hydrolysed nitrogen in the rhizosphere of the root system increased by 43.9 mg/kg. The value of the study lies in the fact that the introduction of short organic crop rotations in farms of various forms of ownership is an innovative approach to providing light grey soils with organic raw materials, restoring and maintaining their fertility, improving their phytosanitary condition, promoting biodiversity, achieving environmental sustainability and high yields

Maize productivity and nutrient status in response to crop residue mineralization with beneficial microbes under various tillage practices

The sustainable intensification of agriculture has become a paramount concern in ensuring global food security on a sustainable basis. Crop residue (CR) management plays a pivotal role in this context, as it influences soil health, nutrients cycling, and overall crop productivity. However, information about the intricate relationship between beneficial microbes (BM), crop residue mineralization, and maize production under various tillage systems is limited. Therefore, we conducted field trials over two years (2018 and 2019) to assess the availability of nutrients and maize yield in response to CR placed at different soil depths with and without BM application. The study consisted of three tillage implements [field cultivator (FC), mouldboard plough (MBP) and chisel plough (CP)], four N augmented CR [no residue (Ro), wheat residue (Rw), chickpea residue (Rc), and Rw+Rc] and two levels of beneficial microbes [BMw -With 250 L BM ton−1 of CR and BMo-without BM]. An in-situ mini litterbag experiment using the CR with and without BM placed up to soil depth of 15, 30, and 45 cm, corresponding to three tillage systems in nylon bags was also performed for C and N decomposition. The field experiment was carried out in randomized complete block design (RCBD) with split plot arrangement having four replications. Tillage implements were allotted to main plots while CR and BM were allotted to sub plots. However, the litterbag study was performed using RCB design. A total of 160 kg N ha−1 was derived as 50% each from CR and urea. The Rc increased the soil mineral N (25.37 and 23.84%) and decreased the SOC (34.45 and 40.56%) over the Rw in soil sampled at maize sowing and harvesting stages, respectively. Similarly, the BM improved the soil mineral N after sowing and/or harvesting stages. The MBP had 13.9% higher grain yield than FC. The Rc had resulted in more ear m−2 (7.2), grains ear−1 (442), 1000 grain weight (319.28 g), and grain yield (8993 kg ha−1) of maize than other CR treatments. Structural equation modelling suggested that dry matter was directly affected by growth contributing components and negatively affected by crop phenological observations. In conclusion, the chickpea crop residues decomposed faster with the addition of BM (BMw) under MBP with improved maize grain yield.

Leaves, Infusion, and Grounds-A Three-Stage Assessment of Element Content in Yerba Mate (Ilex paraguariensis) Based on the Dynamic Extraction and Mineralization of Residues.

The more yerba mate infusions that are consumed, the larger the amount of grounds generated. What is more, both the infusion and the residues after brewing remain rich elements. Therefore, a strategy for the three-stage assessment of the element content was presented. A new brewing method was based on dynamic extraction, ensuring both the ease of preparing the infusion and recovering the grounds. In turn, microwave-assisted acid mineralization was used to decompose the leaves and twigs of yerba mate before and after brewing. In total, 30 products were analyzed by ICP OES in three fractions each, i.e., dry yerba mate, infusion, and grounds, to determine up to 25 elements. The elemental composition was considered in terms of the country of origin, type, or composition of yerba mate. The extraction percentages obtained with dynamic extraction were comparable to previously used ultrasound-assisted extraction, as well as data from the literature. The three-stage strategy is a novel approach in yerba mate studies, and it may be a model procedure for the laboratory preparation of yerba mate grounds (waste that can be re-used, e.g., a natural fertilizer).

Influence of hydro-cycloning, kiln and spray drying on the rheological properties of bentonite clays

Over the years, uncontrolled exploitation of bentonite clays in Boa Vista - PB has resulted in the exhaustion fat clay varieties. Bentonites with a high percentage of residual minerals - contaminants such as quartz - which negatively influence the rheological properties of the dispersions are the current norm. In order to obtain samples with rheological values that meet Petrobras standard EP-1EP-00011-A, this study recommends concentrating dispersions of the less fatty clays through a hydrocycloning, kiln and spray drying operation. Thus, prepared dispersions of two compositions of Bofe, Chocolate, Verde-Lodo and Chocobofe clays, with 4wt.% concentrations, were selected by experimental design to be concentrated through hydrocycloning. The concentrates were kiln and spray dried in two drying configurations. The results proved the efficacy of hydrocycloning and spray drying operations on these mixtures, with remarkable improvements in the rheological properties. Also, there was an increase in the quartz fraction in all wastes and a decrease in the clay mineral concentrates.

Enzyme-accelerated CO2 capture and storage (CCS) using paper and pulp residues as co-sequestrating agents.

In the present work, four CaCO3-rich solid residues from the pulp and paper industry (lime mud, green liquor sludge, electrostatic precipitator dust, and lime dregs) were assessed for their potential as co-sequestrating agents in carbon capture. Carbonic anhydrase (CA) was added to promote both CO2 hydration and residue mineral dissolution, offering an enhancement in CO2-capture yield under atmospheric (up to 4-fold) and industrial-gas mimic conditions (up to 2.2-fold). Geological CO2 storage using olivine as a reference material was employed in two stages: one involving mineral dissolution, with leaching of Mg2+ and SiO2 from olivine; and the second involving mineral carbonation, converting Mg2+ and bicarbonate to MgCO3 as a permanent storage form of CO2. The results showed an enhanced carbonation yield up to 6.9%, when CA was added in the prior CO2-capture step. The proposed route underlines the importance of the valorization of industrial residues toward achieving neutral, or even negative emissions in the case of bioenergy-based plants, without the need for energy-intensive compression and long-distance transport of the captured CO2. This is a proof of concept for an integrated strategy in which a biocatalyst is applied as a CO2-capture promoter while CO2 storage can be done near industrial sites with adequate geological characteristics.

Maize residue input rather than cover cropping influenced N2O emissions and soil–crop N dynamics during the intercrop and cash crop periods

The well-known benefits of cover cropping for mitigating climate change and improving soil quality could be threatened by increased greenhouse gas emissions. Therefore, such practices could have negative consequences in the context of global climate change. The present year-long field experiment, carried out under irrigated semiarid conditions, evaluated the effect of returning maize crop residues at two topsoil input levels in combination with bare fallow, a cereal (barley, Hordeum vulgare L.) and a legume (vetch, Vicia sativa L.) as cover crops as part of an annual cover crop–cash crop (maize, Zea mays L.) rotation. In addition, control plots, without the addition of nitrogen fertilizer (either in the previous cropping season or during the experiment), were established following the same experimental design in order to assess the carry-over impact of residual nitrogen from prior crops. Nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) fluxes were measured together with soil mineral nitrogen and crop yields and nitrogen use efficiency. The significant effect of maize residue input on N2O emissions during the cover crop phase (this was 43% greater for the lower maize residue input than for the higher) was offset after subsequent maize fertilization (there was a 170% increase following the higher maize residue input compared to the lower). Although no differences in soil mineral nitrogen content were reported between treatments before maize fertilization, N2O emissions were 72% higher on the fertilized plots than on the control plots. Before maize fertilization, N2O emissions were increased by the incorporation of cover crop residues and soil rewetting after irrigation, with the highest N2O fluxes being reported for the cereal crop. Cumulative CO2 fluxes were higher in the plots with cover crops (cereal and legume) than in bare fallow plots, while CH4 sink was not affected by cover cropping or maize residue input. The grain yield penalty for maize production (a 7% decrease) with the legume cover crop on the nitrogen fertilized plots (the opposite of what was observed in the control area) highlights the need for an accurate estimation of the nitrogen supply from the mineralization of legume residues. Overall, cover crop and maize residue input did not have any significant effect on annual cumulative N2O emissions, so the positive effects of these practices should be considered to recommend them under semiarid conditions for climate change mitigation and adaptation.

Efficiency of using UAN-32 and Sternifag biopreparation on spring wheat grown with No‑till technology

The results of joint application of the biopreparation Sternifag, SP based on the fungus Trichoderma harzianum and urea ammonium nitrate (UAN-32) on spring wheat cultivated using the No-till technology in the northern forest-steppe of the Priobie region are presented. This zone is characterized by a short growing season and a mean annual moisture coefficient of 1.04–1.08. Under such conditions, No-till, or direct seeding, technology can minimize the cost of grain production. When growing crops according to this technology in the conditions of the northern forest-steppe, the sowing dates are postponed, which actualizes the use of biopreparation to accelerate the mineralization of straw residues. In production and stationary experiments on leached chernozem, the joint application of Sternifag and nitrogen fertilizer in autumn of the previous year activated decomposition of plant residues on second wheat by 33.0–49.0%. Application of the biopreparation together with UAN-32 allowed to obtain in the years of research additional 1 ha 1.5 and 0.96 tons of spring wheat grain (43.7–44.4%) due to an increase in the weight of 1000 grains, ear fineness and better preservation of plants for harvesting. Application of biopreparation Sternifag and UAN-32 on spring wheat grown on the basis of No-till technology in the northern forest-steppe of Priobie is economically beneficial. It is accompanied by an increase in profit by 2.0–2.4 times and an increase in the level of profitability of grain production by 27.0–36.0%. Effectiveness of cultivation of the crop on the background of liquid nitrogen fertilizer UAN-32 is lower. In this variant, grain productivity of spring wheat relative to the control increased in 2018, characterized by high humidity, by 1.1 t/ha, in 2020, characterized by June drought, by 0.74 t/ha. The level of profitability of grain production at application of UAN-32 is higher than in the control by 15.0–17.2%.

Electrochemical In Situ Hydrogen Peroxide Production Can Reduce Microbial Load in Bioponic Nutrient Solutions Derived from Organic Waste

Technological advancement in recent decades has allowed for crop cultivation in soilless controlled environments, known as hydroponics, and this is being employed in an increasing number of factories worldwide. With continued local and regional disruptions in the supply chain to provide mineral fertilizers, new pathways to generate nutrient solutions are being developed. One potential approach is the recovery of nutrients from organic waste and wastewater using bioponics. Bioponics refers to the biological mineralization of organic residues through processes such as anaerobic and aerobic digestion and the use of such organically produced nutrient solutions in hydroponic systems. However, without disinfection of the nutrient solution, the high microbial loads increase the risk of pathogens affecting plant and consumer health. In this work, electrochemical hydrogen peroxide (H2O2) demonstrated success in reducing microbial loads. Different scenarios of application were considered: (1) variation in the H2O2 concentration in the nutrient solution by dosing H2O2 from ex situ electrochemical production, (2) variation in the dosing time-dependent reaction between the nutrient solution and H2O2 produced ex situ, and (3) the in situ production of H2O2 of the organic nutrient solution. The highest tested H2O2 concentration of 200 mg L−1 showed a microbial load reduction of bacteria at 93.3% and of fungi at 81.2%. However, the in situ production showed the highest reduction rate for bacteria and fungi in bioponic nutrient solutions, where longer reaction times also impact microbial concentrations in situ. Final microbial reductions of 97.8% for bacteria and of 99.1% for fungi were determined after a H2O2 production time of 60 min. Overall, our results show that electrochemical H2O2 production can be used to disinfect bioponic nutrient solutions, and the production cell can be implemented in bioponic systems in situ.

Geochemical variations of anatectic melts in response to changes of P–T–H2O conditions: Implication for the relationship between dehydration and hydration melting in the Himalayan orogen

The anatectic mechanism is the most fundamental criterion in determining the petrogenetic relationship between migmatite, granulite and granite at convergent plate margins. Although two main anatectic mechanisms, namely water-absent (dehydration) and water-fluxed (hydration) melting, have been identified in many collisional orogens, their spatiotemporal relationship and genetic connection remain obscure. To address this issue, we conduct an integrated study of forward phase equilibrium and trace element modelling for partial melting of metapelite in the Himalayan orogen. The results are used to decipher changes of phase relation and melt composition in response to changes of temperature, pressure and water content. Pressure and water content mainly affect the solidus and evolving residual mineral assemblages, whereas temperature controls the anatectic reaction. Hydration melting at lower pressure and temperature would produce anatectic melts with relatively high SiO2, FeOT + MgO, CaO, K2O, and Ba contents and SiO2/Al2O3 ratios, but low Al2O3 and Na2O contents and Na2O/K2O and Rb/Sr ratios. In contrast, dehydration melting at higher pressure and temperature would generate anatectic melts with relatively high Al2O3 and Na2O contents and Na2O/K2O and Rb/Sr ratios, but low SiO2, FeOT + MgO, CaO, K2O, and Ba contents and SiO2/Al2O3 ratios. A comparison of geochemical compositions between the modelled melts and the two groups of well-characterized leucogranites in the Himalayan orogen indicates that the coeval dehydration and hydration melting would likely occur at the deeper and shallower crustal levels, respectively. In combination with the secular evolution of metamorphic facies series in the Himalayan orogen, we propose a spatiotemporally coupled dehydration-hydration melting mechanism. The early metamorphism at lower geothermal gradients would result in metamorphic dehydration in the lower crust and hydration in the upper crust during the syn-collisional period in the Early Cenozoic. As a result, the later metamorphism at higher geothermal gradients would lead to dehydration melting in the lower crust and hydration melting in the upper crust during the post-collisional period in the Late Cenozoic. This study highlights the applicability of phase equilibrium and trace element modelling to reveal the geochemical variations of anatectic melts in response to changes of P–T–H2O conditions. This provides new insights into the relationship between dehydration and hydration melting in collisional orogens.