Iron Carbon Research Articles

Effect of Different Multipurpose Tree Species on Physico-chemical Properties of Loamy Sand Soil Under Rainfed Conditions

A field experiment was conducted at Agroforestry Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, during 2019-20. The soils of the experimental field was low in organic carbon (0.24 per cent), available nitrogen (143.50 kg N/ha) and DTPA extractable iron (3.18 mg/kg), medium in available phosphorus (Olsen’s P 48.90 kg P2O5/ha), available potash (180.00 kg K2O/ha), manganese (7.8 mg/kg) and zinc (0.79 mg/kg) and high in copper content (0.61 mg/kg). An experiment consisting of six years old Agroforestry tree plantation which consisted of five multipurpose tree species (MPTs) viz., Tectona grandis, Eucalyptus camaldulensis, Gmelina arborea, Casuriana equstifolia and Melia azadiracht were designed in CRD with four replications. The experiment consisting of 96 trees per species with a plot size of 24 m × 16 m under 4 m × 4 m tree spacing. Among the above six tree species significantly the lowest BD (1.56 Mg/m3), higher WHC (27.87 per cent) and soil porosity (38.03 per cent) was recorded under Casuarinas equisetifolia tree species. Similarly the maximum mean organic carbon (0.445 per cent), available N (165.17 kg/ha), available K2O (196.26 kg/ha) and DTPA extractable iron (4.22 mg/kg) and copper (1.05 mg/kg) content were noted under Casuarina equisetifolia tree species. Whereas, the mean maximum available P2O5 (57.92 kg/ha) was noted under Tectona grandis. The mean maximum DTPA extractable manganese (8.34 mg/kg) and zinc (0.925 mg/kg) was noted under Eucalyptus camaldulensis and Melia azadiracht tree species, respectively.

Accelerated removal of organic pollutants by biochar-based iron carbon granule-activated periodate in chloride-containing water: The role of active chlorine

Ubiquitous in water environments, the chloride ion (Cl−) can impact the decontamination capacity of an oxidation system. However, minimal studies are available on its effects in periodate (PI)-based advanced oxidation processes. In this study, a novel biochar-based iron-carbon (FeBC) granule was synthesized to activate PI and remove organic pollutants from water containing Cl−. The FeBC/PI/Cl− system (FeBC: 0.5 g/L; PI: 0.5 mM; AO7: 20 mg/L; NaCl: 50 mM) exhibited excellent performance on various organic pollutants, with ＞ 85 % of Acid Orange (AO7) removal over a pH range of 3–10. Within 20 min after the tenth run, approximately 80 % of AO7 was removed. Inorganic ions and natural organic matter had a negligible effect on AO7 removal. Characterization results confirmed that the presence of Cl− enhanced Fe corrosion, thereby improving PI activation efficiency for removing AO7. Electron paramagnetic resonance spectroscopy and active species trapping experiments verified that radicals (•OH and O2•−) and nonradical (1O2, Fe(IV), and electron transfer) oxidation processes participated in the FeBC/PI system. Moreover, the presence of Cl− accelerated •OH, O2•−, 1O2, and Fe(IV) formation and generated active chlorine, such as HOCl. The main pathways involved in the generation of multiple reactive species were evaluated. AO7 degradation pathways were proposed, and numerous intermediates exhibited decreased toxicity. These findings provide new insights for the decontamination of organic contaminants in water containing Cl−.

Remote sensing inversion on heavy metal content in salinized soil of Yellow River Delta based on Random Forest Regression—a case study of Gudao Town

To explore the potential of using the mineral alteration information extracted by remote sensing technology to indirectly estimate the heavy metal content of salinized soil, 23 sampling points were uniformly set up in the town of Gudao in the Yellow River Delta as the research area in 2022. The concentrations of seven heavy metals, Cr, Cu, Pb, Zn, As, Mn and Ni, at the sampling points were determined in laboratory tests. Spectral derivative indices, topographic factors, and mineral alteration information (iron staining, hydroxyl, and carbonate ions) were extracted and screened as modeling factors using Sentinel 2 imagery. An inverse model of heavy metal content was constructed using the random forest algorithm, and the model accuracy was evaluated using the cross-validation method. The results of the study show that: (1) Hydroxyl and carbonate ion alteration can be effectively used for the inversion of soil As and Ni content in this study area. Iron-stained alteration can be used as a modeling factor in the inversion of Cr, Cu, Pb, Zn, and Mn concentrations. (2) The inclusion of alteration information improves the accuracy of heavy metal content inversion. The Cu concentration was verified to be the best predictor, with an RMSE of 3.309, MAPE of 11.072%, and R2 of 0.904, followed by As, Ni, and Zn; the predictive value of Mn, Cr and Pb was average. (3) Based on the results of concentration inversion, the high concentration areas of As, Ni, and Mn are primarily distributed on both sides of the river and around lakes and ponds. The high-concentration areas of Zn were mainly distributed in the farmland areas on both sides of the river. Areas with high concentrations of Cu were mainly distributed in the eastern oil extraction area, both sides of the rivers, and around lakes.

Facile fabrication of 3D-α-Fe2O3@2D-g-C3N4 heterojunction composite materials: Effect of iron oxide loading on the electrochemical performance

Designing heterojunction nanocomposites is crucial for optimizing supercapacitor electrodes. This study addresses the challenge by introducing a facile synthesis method for creating 3D-α-Fe2O3@2D-g-C3N4 heterojunctions through a bulk carbon nitride-assisted hydrothermal process. During this process, the growth of ferric oxide particles coincides with the exfoliation and deposition of carbon nitride, leading to simultaneous structural changes in both iron oxide and carbon nitride phases. The resulting composite's properties strongly correlate with the iron oxide loading. Comprehensive characterization using XRD, FTIR, SEM-EDAX, XPS and TEM identified three distinct structures for α-Fe2O3/g-C3N4 composites based on iron oxide loading: low, medium, and high. The medium-loaded sample demonstrated superior electrochemical performance, attributed to better interfacial contact and the formation of 3D-Fe2O3@2D-g-C3N4 heterojunctions. This composite, with an optimized 22 wt% iron oxide loading, exhibited a maximum specific capacitance of 925.1 Fg−1 at 5 mVs−1 and 498.6 Fg−1 at 6 Ag−1 in charge-discharge analysis, with stable performance over 2000 cycles. Overall, this research presents an enhanced hydrothermal method for facile preparation of effective α-Fe2O3/g-C3N4 heterojunction materials.

Free and Combined Carbon in Iron Using CH4 as Carburizing Gas, in the Temperature Range from 900 °C to 1050 °C

Free and Combined Carbon in Iron Using CH4 as Carburizing Gas, in the Temperature Range from 900 °C to 1050 °C

ZIF-8 derived iron-, sulphur-, and nitrogen-doped catalysts for anion-exchange membrane fuel cell application

This study presents the preparation of tridoped Fe, N, S carbon-based catalysts using ZIF-8 as the main carbon source and iron(II)acetate, 1,10-phenanthroline, ammonia gas and thiourea as precursors for Fe, N and S elements. Thiourea was mixed via planetary ball-milling with a Fe–N–C catalyst prepared by inert gas pyrolysis, and different pyrolysis conditions were applied thereafter. The main goal of the work is to synthesise active non-precious metal electrocatalysts for oxygen reduction reaction (ORR). High electrocatalytic ORR activity in alkaline media was observed for the two materials obtained after thiourea addition and subsequent pyrolysis. Physico-chemical characterisation revealed successful S- and N-doping for all three catalysts with enhanced porosity for the two materials that were subjected to additional pyrolysis after the thiourea addition. The sulphur doping was highest for the FeNSC3 material that was subjected to a second pyrolysis in N2 and a third pyrolysis in NH3, compared to the FeNSC2 material that was subjected to a single pyrolysis in NH3 flow after thiourea addition. The ORR activity of FeNSC2 with half-wave potential of 0.88 V was slightly higher than that of FeNSC3, and the former was selected for evaluation as a cathode catalyst in an anion-exchange membrane fuel cell.

Assessment of soil fertility and nutrient management strategies in calcareous soils of Khuzestan province: a case study using the Nutrient Index Value method.

Soil fertility (SF) is a crucial factor that directly impacts the performance and quality of crop production. To investigate the SF status in agricultural lands of winter wheat in Khuzestan province, 811 samples were collected from the soil surface (0-25cm). Eleven soil properties, i.e., electrical conductivity (EC), soil organic carbon (SOC), total nitrogen (TN), calcium carbonate equivalent (CCE), available phosphorus (Pav), exchangeable potassium (Kex), iron (Fe), copper (Cu), zinc (Zn), manganese (Mn), and soil pH, were measured in the samples. The Nutrient Index Value (NIV) was calculated based on wheat nutritional requirements. The results indicated that 100%, 93%, and 74% of the study areas for CCE, pH, and EC fell into the low, moderate, and moderate to high NIV classes, respectively. Also, 25% of the area is classified as low fertility (NIV < 1.67), 75% falls under medium fertility (1.67 < NIV value < 2.33), and none in high fertility (NIV value > 2.33). Assessment of the mean wheat yield (AWY) and its comparison with NIV showed that the highest yield was in the Ramhormoz region (5200kg.ha-1), while the lowest yield was in the Hendijan region (3000kg.ha-1) with the lowest EC rate in the study area. Elevated levels of salinity and CCE in soils had the most negative impact on irrigated WY, while Pav, TN, and Mn availability showed significant effects on crop production. Therefore, implementing SF management practices is essential for both quantitative and qualitative improvement in irrigated wheat production in Khuzestan province.

Modeling remote-sensing and geophysical data to delineate the favorable mineralization localities at Semna area, Central Eastern Desert, Egypt

Semna area is located within the Golden Triangle district in the Central Eastern Desert of Egypt. The study maintains using multisource datasets of remote sensing, aero-spectrometry, aero-magnetic, and field investigations for unraveling the ambiguities associated with the alteration zones at the targeted area. Three remote sensing mapping techniques including; constrained energy minimization, linear spectral unmixing, and mineral indices, were adopted to delineate the alteration zones. The γ-ray spectrometry data of K (%), K/eTh, K/eU, and F-parameter enabled mapping the potassium-enriched localities as indication on possible potassic alteration zones. The surface and subsurface linear structural features were delineated from the digital elevation model and aero-magnetic data, respectively. The outcomes of all the implemented datasets were integrated using GIS overlay modeling, producing an integrated mineralization favorability/potentiality map. Eighteen localities with high potential for mineralization were highlighted. A field study was conducted to the investigated area during which, several alteration indicators were observed, including quartz veins, iron oxides staining, kaolinite, malachite, carbonate, and muscovite (sericite) alteration indicator minerals.

Integrated Remote Sensing for Geological and Mineralogical Mapping of Pb-Zn Deposits: A Case Study of Jbel Bou Dahar Region Using Multi-Sensor Imagery

This research applies remote sensing methodologies for the first time to comprehensively explore the geological and mineralogical characteristics of the Jbel Bou Dahar region. An integrated approach with multi-sensor satellite images, including ASTER, Landsat-8, and Sentinel-2 was applied with the aim to discriminate the different lithological units in the study area. We implemented a suite of well-established image processing techniques, including Band Ratios, Principal Component Analysis, and Spectral Angle Mapper, to successfully identify, classify, and map the spatial distribution of carbonate minerals, OH-bearing minerals, and iron oxide minerals. Due to its high spectral resolution in the short-wave infrared region (SWIR), the ASTER sensor provided the most accurate results for mapping carbonate and OH-bearing minerals compared to the Sentinel-2 and Landsat-8 sensors. Conversely, Sentinel-2 offers high spectral and spatial resolution in visible and near-infrared (VNIR) corresponding to the regions where iron oxide minerals exhibit their characteristic absorption peaks. The results confirm the advantages of remote sensing technologies in the geological and mineralogical exploration of the study area and the importance of selecting the appropriate sensors for specific mapping objectives.

Development of microfiltration membranes based on polysulfone and polyetherimide blends.

In this study, membranes blended with polysulfone (PSU) and polyetherimide (PEI) polymers in different ratios were fabricated. Their potential to remove pollutants from rivers, which are a potential drinking water source, was investigated. Scanning electron microscopy analysis revealed that the PSU membranes had a dense and homogeneous layer, whereas the addition of PEI formed a spongy substrate. The water content of the fabricated membranes varied between 5.37 and 22.42%, porosities 28.73-89.36%, contact angles 69.18-85.81%, and average pure water fluxes 257.25-375.32 L/m2 h. The blended membranes removed turbidity, chloride, alkalinity, conductivity, sulfate, iron, manganese, and total organic carbon up to 98.32, 92.28, 96.87, 90.67, 99.58, 94.63, 97.48, and 79.11%, respectively. These results show that when PEI was added to the PSU polymer, the filtration efficiency increased owing to an increase in the hydrophilicity of the membranes. Blending these two polymers enabled the optimization of membrane properties such as permeability, selectivity, and mechanical strength. In addition, membrane fabrication processes are simple and incur low costs.

ВПЛИВ РУДНОВУГІЛЬНИХ КОМПОЗИЦІЙ У СКЛАДІ ШИХТИ НА ФОРМУВАННЯ ТЕРМІЧНО РЕЗЕРВНОЇ ЗОНИ ДОМЕННОЇ ПЕЧІ

The object of research is the technology of iron smelting when using ore-coal compositions. The purpose of the work is the effect of changing the composition of the blast furnace charge on the thermal state of the formation of the thermal reserve zone. Research methods - theoretical studies are based on the basic principles of physical chemistry and the theory of metallurgical processes. Experimental studies were carried out in laboratory and industrial conditions. Scientific novelty - there is a "coupling phenomenon" between recovery and gasification - this is a close contact between small particles of iron oxides and carbon, which is formed in the ore-coal composite, which ensures an increase in the efficiency of blast furnace smelting. Reduction of fuel consumption and, accordingly, the amount of gases per unit charge of modern blast furnace smelting, the height of the reserve zone is reduced; this zone is not observed in the vertical elements of the furnace with the maximum ore load. Practical significance - the use of ore-coal composites provides a high speed of iron recovery and carbon gasification reactions and a low initial temperature of carbon gasification of 250-420ºС, which is ensured by gas recirculation in the under burden, due to the short distance between the parts of iron-containing and carbon composites and their sizes, where the distance between them is short and the limit of the reaction is "visible" to both.

Hydrogeochemical analysis of groundwater quality during the pre- monsoon season of Manipur, India

ABSTRACT The water quality index (WQI) and irrigational index for groundwater were studied in the northeastern section of the Manipur Valley in northeast India. Water samples were collected in 2022 during the pre-monsoon season. To compute the water quality index for drinking water, the basic chemical parameters of total hardness, pH, electrical conductivity, total dissolved solids, Calcium, Sodium, Iron, Magnesium, Manganese, Chlorine, and Hydrogen Carbonate were used. The assessment of bacteriological quality is also done, which is crucial for overall water quality evaluation, alongside physical and chemical analyze. For determining irrigation suitability, irrigational indices such as sodium absorption ratio, sodium percentage, and magnesium hazard were calculated. WQI, %Na+, Sodium Adsorption Ratio (SAR), magnesium hazard, permeability Index and total hardness indicate that most water samples are harmless for irrigation and drinking purpose. They have affirmative relationships indicating that these characteristics are interdependent. Approximately 25% of the Piedmont zone groundwater is found to be unfit for agricultural and drinking usage. The encrustation of gypsum, halite, and evaporation into the Disang shares accelerate the dissolution of ions in Piedmont water, resulting in quality degradation. According to Gibbs plots, Durov Scatter Plot, and Hill Piper Trilinear Diagram of water dominated the rock-weathering process, while hydrochemical facies progressed from the beginning to the intermediate stage of Chadha’s graphical representation illustrates the progression of hydrochemical processes in surface water. Therefore, proper integrated water resource management and development are required for effective water resource utilization, particularly around the Piedmont zone. In recent years, the quality of groundwater has caused a significant deal of alarm, and an increasing number of studies relating to it have been published. The geological, structural, and geomorphological features in the intermontane Imphal Valley in Manipur, India, were identified using SRTM DEM data by QGIS Software. This area has simple geology and structural elements, making it an appropriate site to evaluate the use of remote sensing and GIS tools in geological studies. To prevent a water crisis, groundwater resources must be managed sustainably. The current study also concentrated on a bibliometric examination of groundwater management and access to gauge the state of the field. A bibliometric examination of these papers may offer insight into current research and trends. We are the first to join Groundwater Quality Assessment with bibliometric analysis. This prediction, if taken into consideration strategically during the planning of preventive measures for groundwater quality can help to analyze future evaluation to a great extent.

Organic amendments increased Chinese milk vetch symbiotic nitrogen fixation by enriching Mesorhizobium in rhizosphere.

Symbiotic nitrogen fixation of Chinese milk vetch (Astragalus sinicus L.) can fix nitrogen from the atmosphere and serve as an organic nitrogen source in agricultural ecosystems. Exogenous organic material application is a common practice of affecting symbiotic nitrogen fixation; however, the results of the regulation activities remain under discussion. Studies on the impact of organic amendments on symbiotic nitrogen fixation have focused on dissolved organic carbon content changes, whereas the impact on dissolved organic carbon composition and the underlying mechanism remain unclear. In situ pot experiments were carried out using soils from a 40-year-old field experiment platform to investigate symbiotic nitrogen fixation rate trends, dissolved organic carbon concentration and component, and diazotroph community structure in roots and in rhizosphere soils following long-term application of different exogenous organic substrates, i.e., green manure, green manure and pig manure, and green manure and rice straw. Remarkable increases in rate were observed in and when compared with that in green manure treatment, with the greatest enhancement observed in the treatment. Moreover, organic amendments, particularly pig manure application, altered diazotroph community composition in rhizosphere soils, therefore increasing the abundance of the host-specific genus Mesorhizobium. Furthermore, organic amendments influence the diazotroph communities through two primary mechanisms. Firstly, the components of dissolved organic carbon promote an increase in available iron, facilitated by the presence of humus substrates. Secondly, the elevated content of dissolved organic carbon and available iron expands the niche breadth of Mesorhizobium within the rhizosphere. Consequently, these alterations result in a modified diazotroph community within the rhizosphere, which in turn influences Mesorhizobium nodulation in the root and symbiotic nitrogen fixation rate. The results of the present study enhance our understanding of the impact of organic amendments on symbiotic nitrogen fixation and the underlying mechanism, highlighting the key role of dissolved organic carbon composition on diazotroph community composition in the rhizosphere.

Isothermal Reduction Kinetics of the Mixture of Iron Carbon Agglomerates and Sinter

Isothermal Reduction Kinetics of the Mixture of Iron Carbon Agglomerates and Sinter

Distinct photochemistry of adsorbed and coprecipitated dicarboxylates with ferrihydrite: Implications for iron reductive dissolution and carbon stabilization

Although ligand-promoted photodissolution of ferrihydrite (FH) has long been known for low molecular weight organic acids (LMWOAs), such as oxalate (Oxa) and malonate (Mal), photochemistry of coprecipitated FH with Oxa and Mal remains unknown, despite the importance of these mineral-organic associations in carbon retention has been acknowledged recently. In this study, ferrihydrite-LMWOAs associations (FLAs) were synthesized under circumneutral conditions. Photo-dissolution kinetics of FLAs were compared with those of adsorbed LMWOAs on FH surface and dissolved Fe-LMWOAs complexes through monitoring Fe(II) formation and organic carbon decay. For aqueous Fe(III)-LMWOAs complexes, Fe(II) yield was controlled by the initial concentration of LMWOAs and nature of photochemically generated carbon-centered radicals. Inner-sphere mononuclear bidentate (MB) configuration dominated while LMWOAs were adsorbed on the FH surface. MB complex of FH-Oxa was more photoreactive, leading to the rapid depletion of Oxa. Oxa can be readsorbed but in the form of binuclear bidentate and outer-sphere complexation, with much lower photoreactivity. While LMWOAs was coprecipitated with FH, the combination mode of LMWOAs with FH includes surface adsorption with a mononuclear bidentate structure and internal physical inclusion. Higher content of LMWOAs in the FLAs promoted the photo-production of Fe(II) as compared to pure FH, while it was not the case for FLAs containing moderate amounts of LMWOAs. The distinct photochemistry of adsorbed and coprecipitated Fe-LMWOAs complexes is attributed to ligand availability and configuration patterns of LMWOAs on the surface or entrapped in the interior structure. The present findings have significant implications for understanding the photochemical redox cycling of iron across the interface of Fe-organic mineral associates.

Study of a New Photocatalytic Film Process Combined with a Constructed Wetland and an Analysis of Reoxygenation Pathways in a Water Body

Pollution in water environments hinders both social progress and economic development. Wastewater treatment and the sustainable use of water resources are important factors in solving this problem. In a previous study, the authors proposed a process that used photocatalytic film as a back-end treatment in a composite iron–carbon constructed wetland (WIC&amp;PF) to restore a mildly eutrophic water body. This method has strong reoxygenation effects, and can efficiently remove pollutants; these are qualities that have not been mentioned in previous studies regarding constructed wetlands. In this study, the authors further investigated the effectiveness of this process by using a photocatalytic film as a front-end treatment for a composite iron–carbon constructed wetland (PF&amp;WIC) to restore a mildly eutrophic water body. The results showed NH4+-N, TN, TP, COD, and chlorophyll a removal rates using PF&amp;WIC of 79.1 ± 6.6%, 76.8 ± 6.5%, 77.0 ± 5.4%, 77.3 ± 7.2%, and 91.7 ± 5.6%, respectively. The DO concentration of the water body increased compared with that of the effluent. The bacterial species and their abundance in the lake water also changed significantly, and photosynthetic autotrophic bacteria (Cyanobium PCC-6307) became the most dominant bacteria, and this played an important role in reoxygenating the water body. In comparing these results to those of our previous study, the removal of pollutants with PF&amp;WIC was close to that with WIC&amp;PF, but the reoxygenation effect of PF&amp;WIC on the water body was significantly worse than that of WIC&amp;PF; thus, WIC&amp;PF is the more reasonable choice for treating eutrophic water bodies.

Adsorption of Pyrene and Arsenite by Micro/Nano Carbon Black and Iron Oxide.

Polycyclic aromatic hydrocarbons (PAHs) and arsenic (As) are common pollutants co-existing in the environment, causing potential hazards to the ecosystem and human health. How their behaviors are affected by micro/nano particles in the environment are still not very clear. Through a series of static adsorption experiments, this study investigated the adsorption of pyrene and arsenite (As (III)) using micro/nano carbon black and iron oxide under different conditions. The objectives were to determine the kinetics and isotherms of the adsorption of pyrene and As (III) using micro/nano carbon black and iron oxide and evaluate the impact of co-existing conditions on the adsorption. The microstructure of micro/nano carbon black (C 94.03%) is spherical-like, with a diameter of 100-200 nm. The micro/nano iron oxide (hematite) has irregular rod-shaped structures, mostly about 1 µm long and 100-200 nm wide. The results show that the micro/nano black carbon easily adsorbed the pyrene, with a pseudo-second-order rate constant of 0.016 mg/(g·h) and an adsorption capacity of 283.23 μg/g at 24 h. The micro/nano iron oxide easily adsorbed As (III), with a pseudo-second-order rate constant of 0.814 mg/(g·h) and an adsorption capacity of 3.45 mg/g at 24 h. The mechanisms of adsorption were mainly chemical reactions. Micro/nano carbon black hardly adsorbed As (III), but its adsorption capability for pyrene was reduced by the presence of As (III), and this effect increased with an increase in the As (III) concentration. The adsorbed pyrene on the micro/nano black carbon could hardly be desorbed. On the other hand, the micro/nano iron oxide could hardly adsorb the pyrene, but its adsorption capability for As (III) was increased by the presence of pyrene, and this effect increased with an increase in the pyrene concentration. The results of this study provide guidance for the risk management and remediation of the environment when there is combined pollution of PAHs and As.

Research on the Transformation Mechanism of Soil Cadmium Fractions under the Conditions of Freeze-thaw and Crude Oil Contamination in Wetlands in the Songnen Plain, China

Environmental changes can significantly affect heavy metals behave in soil. Currently, we know little about the impact of crude oil contamination on heavy metal fractions in soil, with few studies available on heavy metal fraction transformation under the composite action of freeze-thaw and crude oil contamination. In this study, soil samples were collected from the Momoge Wetland in the Songnen Plain. Properties including pH, cation exchange capacity, calcium carbonate, free iron oxide, dissolved organic carbon, microbial biomass carbon, and cadmium (Cd) fractions under freeze-thaw, crude oil contamination, and the two combined (composite action) were analysed. The results show that under freeze-thaw, crude oil contamination, and composite action, soil properties changed significantly; soil water-soluble Cd content significantly increased by 54.17%, 62.50%, and 33.33% from control levels, respectively; soil ion-exchangeable Cd content decreased significantly by 10.90%, 23.73%, and 18.64% from control levels, respectively; soil residual Cd content significantly increased by 80.36%, 94.64%, and 132.14% from control levels, respectively; carbonate-bound, humic acid-bound, Fe-Mn oxide-bound, and strongly organic-bound Cd did not change significantly. Soil dissolved organic carbon, pH, CaCO3, and free iron oxide were significantly correlated with water-soluble, ion-exchangeable, carbonate-bound, and Fe-Mn oxide-bound Cd, respectively. This study provides a theoretical basis for evaluating soil Cd behaves in crude oil contaminated wetlands in cold regions.

Mapping Dissolved Organic Carbon and Organic Iron by Comparing Deep Learning and Linear Regression Techniques Using Sentinel-2 and WorldView-2 Imagery (Byers Peninsula, Maritime Antarctica)

Byers Peninsula is considered one of the largest ice-free areas in maritime Antarctica. Since 2006, the Spanish Polar Program has taken part in a large number of environmental studies involving the effects of climate change on biological life cycles, limnology, and microbiology. Soils from maritime Antarctica are generally weakly developed and have chemical, physical, and morphological characteristics that are strongly influenced by the parent material. However, biological activity during the short Antarctic summer promotes intense transference of nutrients and organic matter in areas occupied by different species of birds and marine mammals. Mapping and monitoring those areas that are highly occupied by various species could be very useful to create models prepared from satellite images of the edaphic properties. In this approach, deep learning and linear regression models of the soil properties and spectral indexes, which were considered as explicative variables, were used. We trained the models on soil properties closely related to biological activity such as dissolved organic carbon (DOC) and the iron fraction associated with the organic matter (Fe). We tested the best approach to model the spatial distribution of DOC, Fe, and pH by training the linear regression and deep learning models on Sentinel-2 and WorldView-2 images. The most robust models, the pH model built with the deep learning approach on Sentinel images (MAE of 0.51, RMSE of 0.70, and R2 with a residual of −0.49), the DOC model built with linear regression on Sentinel images (MAE of 189.39, RMSE of 342.23, and R2 with a residual of 0.0), and the organic Fe model built with deep learning (MAE of 116.20, RMSE of 209.93, and R2 of −0.05), were used to track possible areas with ornithogenic soils, as well as areas of Byers Peninsula that could be supporting the highest biological development.

The role of intrinsic soil properties in the compressive strength and volume change behavior of unstabilized earth mortars

Despite the growing interest in earthen construction, there is critical lack of reliable experimental data on the soil properties which mostly affect the engineering characteristics of the dried building material. Therefore, the main objective of this research was to explore the influence of some of these properties, namely clay fraction content, Specific Surface Area (SSA), Cation Exchange Capacity (CEC), chemical and mineralogical composition and various forms of iron and calcium carbonate on earth mortars. The initial trigger for this research was the extraordinary compressive strength of four earth mortars prepared with different soils. So, these four soils, along with seven others from previous research, were thoroughly examined using soil science techniques to investigate the link between soil properties and compressive strength and linear shrinkage of earth mortars. A relationship between the compressive strength to CEC ratio and dry density was found, highlighting the decisive role of clay activity as expressed by CEC, in earthen materials properties. According to linear regression and dominance analysis, the strongest correlation was exhibited by SSA followed by CEC, demonstrating that compressive strength is largely dependent on these two properties. Less strong correlation was found for clay fraction content, while poorly ordered/amorphous iron oxides were found to correlate with strength and shrinkage, but their contribution requires further research. Regarding the mineralogical properties, it was found that the mortars that achieved the highest strengths contained poorly crystalline smectite clays. Finally, even significant differences in soil chemical composition did not necessarily lead to different mortar properties.