Search Results (265)

Cilantro (Coriandrum sativum L.) is a popular annual culinary herb grown for its leaves or seeds. With the increase in hydroponic herb production in controlled environments, a need exists for leaf tissue nutrient standards specific to this production system. The objective of this study was to develop comprehensive foliar mineral nutrient interpretation ranges for greenhouse-grown cilantro. Cilantro plants were grown in a hydroponic sand culture system to induce and document nutritional disorders. Plants were supplied with a modified Hoagland’s solution, which was adjusted to individually add or omit one nutrient per treatment while holding all others constant. Deficiency and toxicity symptoms were photographed, after which the plant tissue was collected to determine plant dry weight and critical tissue nutrient concentrations. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), iron (Fe), and zinc (Zn) deficiencies, as well as B toxicity, were induced. Deficiencies of copper (Cu), manganese (Mn), and molybdenum (Mo) were not observed during the experiment. Additional foliar tissue analysis data (n = 463) were compiled to create nutrient interpretation ranges for 12 essential elements based on a hybrid meta-analysis Sufficiency Range Approach (SRA). This approach defines ranges for deficient, low, sufficient, high, and excessive values. For each element, the optimal distribution was selected according to the lowest Bayesian Information Criterion (BIC) value. A Normal distribution best represented K and S. A Gamma distribution best represented P, Ca, Mn, and Mo, whereas a Weibull distribution best represented N, Mg, B, Cu, Fe, and Zn. These interpretation ranges, along with descriptions of typical symptomology and critical tissue nutrient concentrations, provide useful tools for both diagnosing nutritional disorders and interpreting foliar nutrient analysis results of greenhouse-grown cilantro. Full article

Understanding the differences in the adsorption behaviors of tetrabromobisphenol A (TBBPA) and tetrabromobisphenol S (TBBPS) on soils is critical for assessing their environmental mobility and risks. This study investigated the adsorption characteristics and patterns of TBBPA/S across various soil types. Adsorption kinetics analysis indicated that the adsorption of TBBPA/S on soils followed pseudo-secondary-order kinetics. Isotherm results revealed that the Langmuir model described TBBPA adsorption more accurately, while the Freundlich model was a better fit for TBBPS adsorption, suggesting distinct adsorption mechanisms due to their differing properties. Correlation analysis and principal component analysis (PCA) were performed to identify the key soil physicochemical properties influencing TBBPA/S adsorption. The results showed that TBBPA adsorption was inversely correlated with soil pH and positively correlated with clay content. In contrast, TBBPS adsorption displayed negative correlations with soil pH and sand content, and positive correlations with amorphous iron, amorphous aluminum, and free iron content. Further analysis of different treated soil fractions demonstrated that soil organic matter dominated the adsorption of TBBPA/S, with humic acid playing a more significant role than humin. The adsorption behavior characteristics of TBBPA/S on different soils provide fundamental data for understanding their environmental fate in soil systems. Full article

Effective arsenic removal is a challenge when smelting high-arsenic copper minerals (HACMs, As > 3.0 wt%). Current arsenic-removal methods for HACM smelting cannot effectively remove arsenic and do not satisfy environmental requirements. This study argues that two-stage filtration based on Fe-25Al porous material and oxygen-controlled roasting is an effective technique for HACM arsenic removal (As = 11.8 wt%). The use of two-stage filtration facilitated double interception: particles larger than 10 μm were mechanically intercepted by the pore channels, and submicron particles (0.1–10 μm) were intercepted by the filter cake. Specifically, in the second stage, the flue gas underwent gradient rapid cooling, and the arsenic in the flue gas rapidly condensed, resulting in efficient arsenic removal. The purity of the condensed product, As₂O_3, was greater than 99%. Moreover, adding sand to the roasted mineral increased the specific surface area from 0.484 m²/g to 0.590 m²/g, reducing the “bottleneck effect” of pores; the addition of carbon further increased the surface area to 2.457 m²/g, inhibiting the formation of arsenate. When the mineral feed rate increased from 50 kg/h to 80 kg/h, the oxygen partial pressure decreased; this effectively inhibited the formation of iron arsenate, and the arsenic removal efficiency increased from 70.20% to 95.61%. The optimized process achieved ≥94% arsenic removal efficiency and ≥76% sulfur-fixation efficiency, with low energy cost. Material balance analysis showed that after arsenic removal, the Cu/Si to Fe/Si ratio of the copper mineral reached 1.5, which is appropriate for immediate subsequent smelting. This study provides a new technological strategy for HACM arsenic removal. Full article

To elucidate the effects of iron ore tailings (IOTs) and basalt fiber (BF) on the durability of recycled aggregate concrete (RAC) with different recycled aggregate replacement rates, this study used IOTs to replace natural sand at mass replacement rates of 0%, 20%, 40%, 60%, 80%, and 100% and incorporated BF at volume fractions of 0%, 0.1%, 0.2%, and 0.3%. Carbonation and freeze–thaw cycle tests were conducted on C30 grade RAC. The carbonation depth and compressive strength of RAC at different carbonation ages and the mass loss rate, relative dynamic elastic modulus, and changes in compressive strength of RAC under different freeze–thaw cycle times were determined. Scanning electron microscopy (SEM) was utilized to meticulously observe the micro-morphological alterations of BF-IOT-RAC before and after carbonation. We then investigated the mechanisms by which BF and IOTs enhance the carbonation resistance of RAC. Utilizing the experimental data, we fitted relevant models to establish both a carbonation depth prediction model and a freeze–thaw damage prediction model specific to BF-IOT-RAC. Furthermore, we projected the service life of BF-IOT-RAC under conditions typical of northwest China. The results showed that as the dosages of the two materials increased, the carbonation resistance and frost resistance of RAC initially improved and then declined. Specifically, the optimal volume content of BF was ascertained to be 0.1%, while the optimal replacement rate of IOTs was determined to be 40%. Compared to using BF or IOTs individually, the composite incorporation of both materials significantly improves the durability of RAC while simultaneously enhancing the reuse of construction waste and mining solid waste, thereby contributing to environmental sustainability. Full article

Industrial wastewater management remains a critical barrier to achieving Sustainable Development Goal 6 (SDG 6) in many developing countries, where regulatory frameworks exist but affordable and scalable treatment solutions are lacking. In Pakistan, the textile sector is a leading polluter, with untreated effluents routinely discharged into rivers and agricultural lands despite stringent National Environmental Quality Standards (NEQS). This study presents a pilot-scale case from Faisalabad’s Khurrianwala industrial zone, where a decentralized, nature-based bioreactor was piloted to bridge the gap between policy and practice. The system integrates four treatment stages—anaerobic digestion (AD), floating treatment wetland (FTW), constructed wetland (CW), and sand filtration (SF)—and was further intensified via nutrient amendment, aeration, and bioaugmentation with three locally isolated bacterial strains (Acinetobacter junii NT-15, Pseudomonas indoloxydans NT-38, and Rhodococcus sp. NT-39). The fully intensified configuration achieved substantial reductions in total dissolved solids (TDS) (46%), total suspended solids (TSS) (51%), chemical oxygen demand (COD) (91%), biochemical oxygen demand (BOD) (94%), nutrients, nitrogen (N), and phosphorus (P) (86%), sulfate (26%), and chloride (41%). It also removed 95% iron (Fe), 87% cadmium (Cd), 57% lead (Pb), and 50% copper (Cu) from the effluent. The bacterial inoculants persist in the system and colonize the plant roots, contributing to stable bioremediation. The treated effluent met the national environmental quality standards (NEQS) discharge limits, confirming the system’s regulatory and ecological viability. This case study demonstrates how nature-based systems, when scientifically intensified, can deliver high-performance wastewater treatment in industrial zones with limited infrastructure—offering a replicable model for sustainable, SDG-aligned pollution control in the Global South. Full article

Mining activities generate large volumes of tailings with significant environmental impact but also the potential for sustainable reuse in construction materials. This study evaluates the production of ceramic aggregates from mixtures of clay, sand, and iron ore waste subjected to thermal treatment at temperatures ranging from 600 to 1100 °C. The influence of calcination temperature on mineralogical transformations and mechanical integrity was investigated using X-ray diffraction (XRD) and the $\alpha$-Treton parameter, derived from standardized impact resistance testing. The results indicate that the formation of metakaolinite between 700 and 900 °C enhances mechanical resistance, while higher temperatures (>900 °C) lead to structural degradation, followed by partial recovery due to mullite crystallization. The $\alpha$-Treton curve exhibited clear correlation with the phase changes identified by XRD, demonstrating its applicability as a low-cost, sensitive proxy for optimizing thermal activation. A simplified methodology is proposed to optimize the thermal activation of such materials by correlating firing temperature with mineralogical evolution and mechanical integrity, contributing to the development of sustainable ceramic aggregates for pavement applications. Full article

The management of spent foundry sand (SFS) presents environmental and operational challenges for foundries. According to the European Union, European foundries generate approximately 9 million tonnes of SFS annually, mainly from the production of ferrous castings (iron and steel). Nowadays, around 25% of the spent foundry sand in Europe is recycled for specific applications, primarily in the cement industry. However, the presence of chemical residues limits the application of this solution. A possible alternative for reusing the spent foundry sand is its employment as a raw material in the production of compost. Studies in the literature indicate that the amount of chemical residue present in the sand can be reduced through the composting process, making the final product suitable for different purposes. However, information about the implementation of this technology in industrial contexts is lacking. To address this issue, this paper proposes a techno-economic analysis to assess the feasibility of composting SFS on a large scale, using information gathered during the testing phase of the Green Foundry LIFE project. This project explored the reuse of sand from organic and inorganic binder processes to create compost for construction purposes, which allowed for the final product. Since the new BREF (Best Available Techniques Reference Document) introduced by the European Union at the start of 2025 recommends composting SFS as a way to reduce solid waste from foundries, this initial study can represent practical guidance for both researchers and companies evaluating the adoption of this technology. Full article

Nickel aluminum bronze (NAB) and manganese aluminum bronze (MAB) are widely used in propulsion and seawater handling systems in naval platforms due to their attractive combination of mechanical strength, toughness, and very low susceptibility to marine corrosion. Nevertheless, it is well known that they can suffer from selective phase corrosion and erosion–corrosion, primarily caused by cavitation and sand erosion. Both alloys have a multiphase microstructure that governs their mechanical and chemical behavior. The tribocorrosion behavior of cast NAB and MAB alloys was studied in artificial seawater to analyze the effect on microstructure. The microstructure and nanohardness were evaluated and correlated with tribocorrosion test results conducted under two different loads (10 and 40 N) in a unidirectional sliding mode using a 1 M NaCl solution as the electrolyte. A significant increase in the corrosion rate due to the wear effect was observed in both alloys. MAB exhibited a slightly better tribocorrosion performance than NAB, which was attributed to significant differences in the shape, distribution, and size of the intermetallic kappa phases—rich in iron, aluminum, and nickel—within the microstructure. Pitting corrosion was observed in NAB, while selective corrosion of kappa phases occurred in MAB, highlighting the role of the protective layer in the tribocorrosion behavior of both alloys. These findings were supported by post-test solution analysis using ICP-AES and corrosion product characterization by EDX. A synergistic effect between wear and corrosion was confirmed for both alloys, as erosion removes the protective layer, exposing fresh material to continuous friction and favoring a progressive material loss over time. The practical impact of this study lies in improving the control and design of highly alloyed bronze microstructures under in-service corrosion–erosion conditions. Full article

This study investigates hazardous emissions from foundry binder systems, comparing organic resins (phenolic urethane, furan, and alkaline-phenolic) and clay-bonded green sand with inorganic alternatives (sodium silicate and geopolymer). The research was conducted at the Fundaciόn Azterlan pilot plant (Spain), involving controlled chamber tests for the production of 60 kg iron alloy castings in 110 kg sand molds. The molds were evaluated under two configurations: homogeneous systems, where both mold and cores were manufactured using the same binder (five trials), and heterogeneous systems, where different binders were used for mold and cores (four trials). Each mold was placed in a metallic box fitted with a lid and an integrated gas extraction duct. The lid remained open during pouring and was closed immediately afterward to enable efficient evacuation of casting gases through the extraction system. Although the box was not completely airtight, it was designed to direct most exhaust gases through the duct. Along the extraction system line, different sampling instruments were strategically located for the precise measurement of contaminants: volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), phenol, multiple forms of particulate matter (including crystalline silica content), and gases produced during pyrolysis. Across the nine trials, inorganic binders demonstrated significant reductions in gas emissions and priority pollutants, achieving decreases of over 90% in BTEX compounds (benzene, toluene, ethylbenzene, and xylene) and over 94% in PAHs compared to organic systems. Gas emissions were also substantially reduced, with CO emissions lowered by over 30%, NO_x by more than 98%, and SO₂ by over 75%. Conducted under the Greencasting LIFE project (LIFE 21 ENV/FI/101074439), this work provides empirical evidence supporting sodium silicate and geopolymer binders as viable, sustainable solutions for minimizing occupational and ecological risks in metal casting processes. Full article

This study presents a simulation modeling of the gravity filling of a sand casting mold with gray cast iron EN-GJL-250. An analysis of the fluid flow, the nature of the filling of the casting mold, and the possibility of forming defects, such as voids and porosity due to metal shrinkage during the crystallization process, was performed. The simulation was performed using specialized software for simulating metal casting processes. The software allows the modeling of fluid dynamics and thermal conditions during the filling of the casting mold. The results obtained show the influence of the design of the sprue system, pouring temperature, and casting geometry on the movement of the fluid flow and the crystallization of the metal. The simulation also allows the visualization of turbulence and temperature gradients, helping to localize areas prone to defects. The results of this study could improve the quality of the specific casting and aid in selecting appropriate technology for the casting of a small series of high-quality castings. Full article

A core tertiary wastewater reactive filtration technology, where continuously renewed hydrous ferric oxide coated sand is created in an upflow continuous backwash filter, has been adopted in about 100 water resource recovery facilities in several countries. Primarily focused on ultralow phosphorus discharge requirements to address nutrient pollution impacts and harmful algae blooms, the technology has also demonstrated the capacity to address high-efficiency removals of Hg, As, Zn, N, and other pollutants of concern, in addition to water quality needs met by common sand filtration, including total suspended solids. Recent work has demonstrated the capability of an additive iron–ozone catalytic oxidation process to the core reactive filtration technology platform to address micropollutants such as pharmaceuticals. Most recently, direct injection of frangible biochar into the reactive sand filter bed as a consumable reagent demonstrates a novel biochar water treatment technology in a platform that yields dose-dependent carbon negativity. In this work, the reactive filtration technology performance is reviewed from field pilot-scale to full-scale installation scenarios for nutrient removal and recovery applications. We also review the potential of the technology for nutrient recovery with the addition of biochar and micropollutant destructive removal with catalytic oxidation. Research exploration of this reactive filtration technology includes life cycle assessment (LCA) and techno-economic assessment to evaluate the environmental and economic impacts of this advanced water treatment technology. A recent LCA study of a pilot-scale field research and full-scale municipal system with over 2200 inventory elements shows a dose-dependent carbon negativity when biochar is injected into the process stream of reactive filtration. In this study, LCA demonstrates that reactive filtration has the potential as a negative emissions technology with −1.21 kg CO₂e/m³, where the negative contribution from the dosed biochar is −1.53 kg CO₂e/m³. In this biochar water treatment configuration, the system not only effectively removes pollutants from wastewater but also contributes to carbon sequestration and nutrient recovery for agriculture, making it a potentially valuable approach for sustainable water treatment. Full article

As an endogenous hormone, auxin plays a crucial role in regulating plants’ growth and development, and also in the responses to abiotic stresses. However, the effects and mechanism of auxin and its inhibitors on plant growth and mineral nutrient absorption in citrus have not been thoroughly studied. Therefore, we used trifoliate orange (citrus’s rootstock, Poncirus trifoliata) as the experimental material to supplement the research content in this area. The trifoliate orange seedlings were treated with exogenous auxin (indolebutyric acid, IBA) and auxin inhibitor (2-naphthoxyacetic acid, 2-NOA) in a sand culture system. The results showed that compared to the control, exogenous auxin (1.0 µmol L⁻¹ IBA) significantly enhanced the taproot length, lateral root length, and lateral root number by 17.56%, 123.07%, and 88.89%, respectively, while also markedly elevating the levels of nitrogen (N), phosphorus (P), potassium (K), copper (Cu), and zinc (Zn) by 14.29%, 45.61%, 23.28%, 42.86%, and 59.80%, respectively. Again compared to the control, the auxin inhibitor (50.0 µmol L⁻¹ 2-NOA) dramatically reduced the taproot length, lateral root length, and lateral root number by 21.37%, 10.25%, and 43.33%, respectively, while also markedly decreasing the levels of N, magnesium (Mg), iron (Fe), Cu, and Zn by 7.94%, 10.42%, 24.65%, 39.25%, and 18.76%, respectively. Furthermore, IBA increased auxin accumulation in the root hair, stele, and epidermal tissues of citrus taproots, and promoted the up-regulation of auxin synthesis genes (TAR2, YUC3, YUC4, YUC6, YUC8) and transport genes (ABCB1, ABCB19, AUX1, LAX1, LAX2, PIN1, PIN3, PIN4). In contrast, 2-NOA decreased auxin levels in the root hair, stele, and epidermal tissues of citrus taproots, and was involved in the down-regulation of auxin synthesis genes (TAR2, YUC3, YUC4, YUC6) and transport genes (ABCB1, AUX1, LAX1, LAX2, LAX3, PIN3). Interestingly, 2-NOA dramatically elevated auxin level specifically in the root tip of citrus taproot. Therefore, 2-NOA disrupts auxin reflux from the root tip to root hair and epidermal tissues in citrus taproot through down-regulation of auxin transport genes, thereby creating localized (i.e., root hair zone and epidermal tissues) auxin deficiencies that compromise root system architecture and nutrient acquisition capacity. According to the results of this study, exogenous auxin analogs could regulate citrus growth and mineral nutrient absorption through the auxin synthesis and transport pathways. Full article

The Luhai uranium deposit is a large-scale uranium deposit newly discovered in recent years through comprehensive prospecting methods. It is located in the Basaiqi Paleochannel Uranium metallogenic belt of the Erlian Basin and is characterized by its shallow burial and large scale. This paper provides new data on the genetic processes of sandstone-type uranium mineralization through sedimentological and geochemical environmental indicators (such as Fe³⁺/Fe²⁺, organic carbon, total sulfur, etc.), analysis of C-O isotopes of carbonate cements and H-O isotopes of groundwater, and geochemical and mineralogical studies of uranium minerals, iron–titanium oxides (involving backscatter analysis, micro-area chemical composition determination, and elemental surface scanning), and organic matter. Sedimentological analysis shows that the ore- bearing layer in the upper member of the Saihan Formation developed a braided channel within floodplain subfacies, which control the distribution of uranium ore bodies. Uranium mineralogical observations, geochemical environmental indicators, and organic geochemical data indicate that the main reducing agents related to mineralization are pyrite, terrestrial plants, and deep-sourced oil and gas. The δD values of groundwater in the ore-bearing layer range from −95.34‰ to −90.68‰, and the δ¹⁸O values range from −12.24‰ to −11.87‰. For calcite cements, the δ¹⁸O_V-PDB values range from −24‰ to −11.5‰, and the δ¹⁸_OV-SMOW values range from 6.2‰ to 19‰. It was determined that the ore-forming fluid is mainly surface fresh water that entered the strata during the tectonic uplift stage, with local mixing of deep-sourced brine. Based on these data, the main modes of uranium mineralization in the paleochannel were obtained as follows: (1) Redox mineralization occurs due to the reducing medium within the sand body itself and the reduction caused by deep- sourced oil and gas generated from the Tengge’er and Arshan Formations. (2) Mineralization is achieved through the mixing of fluids from different sources. Furthermore, a genetic model related to uranium mineralization in the paleochannels of the Luhai area has been established: favorable uranium reservoirs were formed during the sedimentary period, and during the post-sedimentary stage, reverse structures promoted redox reactions and fluid-mixing-induced mineralization. The research findings can provide guidance for the exploration of paleochannel sandstone-type uranium deposits in other areas of the Erlian Basin. Full article

This study investigates the influence of casting thickness on the cooling rate of gray cast iron using metal molds and compares it to the cooling rate achieved with traditional sand molds. Sand molds represent the oldest and most widely used method in metal casting, while metal molds are a relatively newer application for gray cast iron. The cooling rates during solidification were monitored using thermocouples connected to a data logger. The smelting of gray cast iron was performed in an induction furnace, with some samples inoculated using FeSi and FeMn additions, while others were cast without inoculation. This study analyzed the chemical composition, microstructure, hardness, and surface morphology of gray cast iron through SEM-EDS for both inoculated and non-inoculated samples. The results indicate that FeSi and FeMn inoculation enhanced the carbon content of the cast iron. Additionally, while the differences in cooling rate due to the casting thickness in permanent metal molds were not substantial, a distinct pattern emerged. The mid-thickness regions exhibited the highest cooling rates, which influenced the hardness distribution across the castings. This research highlights the nuanced effect of the mold type and casting thickness on the cooling dynamics and mechanical properties of gray cast iron. Full article

The Lhasa River, as one of the major rivers on the Tibetan Plateau, is of great value for the study of climate and environmental changes on the Tibetan Plateau. In this paper, the grain size and the mineralogical and geochemical characteristics of the sediments from the Lhasa River were investigated. The results show the following: (1) The average grain size of the Lhasa River sediments is coarse (65.5% sand, 23.6% silt), and the sorting is overall poor; the skewness is mostly positive, and the kurtosis is wide, which reflects the obvious characteristics of river sand deposition. (2) The mineral composition of the Lhasa River sediments is dominated by quartz (38.4%), feldspar, and plagioclase feldspar, followed by clay minerals, and the content of carbonate minerals is relatively low; the content of clay minerals in the illite content is as high as 83.3%, while the chlorite content is slightly higher than kaolinite, and smectite content is very low. The chemical index of illite is less than 0.4, indicating that illite is mainly iron-rich magnesium illite. (3) The value of the chemical weathering index (CIA) of the sediments is low, implying that the sediments are in a weak–moderate chemical weathering state and dominated by physical weathering. Comprehensive analyses further revealed that the weathering process of the sediments in the Lhasa River was influenced by both climate and lithology, i.e., sediment composition is influenced not only by chemical weathering in a dry, cold climate but also by physical weathering of granites exposed over large areas. The results of this study can provide scientific references for further in-depth research on the environmental and climatic effects of the Tibetan Plateau. Full article