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Inorganic carbon is the largest source of carbon in terrestrial surface, particularly in arid and semiarid regions, including the Chahardowli Plain in western Iran. Inorganic carbon plays an equal or greater role than organic soil carbon in these areas, although less attention has been paid in quantifying their variability. The objective of this study was to model and map calcium carbonate equivalent (CCE) presenting inorganic carbon in soil using machine learning and digital soil mapping techniques. Chahardowli Plain in foothills of the Zagros Mountains in the southeast of Kurdistan Province in Iran was taken as a case study area. CCE was measured at 0–5, 5–15, 15–30, 30–60, and 60–100 cm depths following GloalSoilMap.net project specifications. A total of 145 samples were collected from 30 soil profiles using the conditional Latin hypercube (cLHS) method of sampling. Relationships between CCE and environmental predictors were modeled using random forest (RF) and decision tree (DT) models. In general, the RF model performed slightly superior than the DT model. The mean value of CCE increased with soil depth, from 3.5% (0–5 cm) to 63.8% (30–60 cm). Remote sensing (RS) variables and terrestrial variables were equally important. The importance of RS variables was higher at the surface than terrestrial variables, and vice versa. The most significant variables were Channel Network Base Level (CNBL) variable and Difference Vegetation Index (DVI) with the same variable importance value (21.1%). In areas affected by river activities, the use of the CNBL and vertical distance to channel networks (VDCN) as variables in digital soil mapping (DSM) could increase the accuracy of soil property prediction maps. The VDCN played a principal role in soil distribution in the study area by affecting the rate of discharge and, thus, erosion and sedimentation. A high percentage of carbonate in parts of the region could exacerbate nutrient deficiencies for most crops and provide information for sustainably managing agricultural activity.

Soils play an important role in the balance of carbon on the global scale. The study of the carbon cycle in Calcareous soils has received less attention, while Calcareous soils cover a third of the world’s soils and most croplands of Iran. The aim of this study was to investigate soil organic carbon fractions and the relationship of soil organic carbon (SOC) with soil properties in 30 wheat farms of Calcisols of Alborz, Iran. To study the effects of soil geochemical properties, the data were subjected to cluster analysis to select samples with similar texture and low salinity. We applied a densimetric method using sodium iodide (NaI) to isolate light fraction (LF < 1.6 g/cm 3 ), occluded fraction (OF < 1.8 g/cm 3 ), and mineral-associated organic matter (MAOM > 1.8 g/cm 3 ) of selected soils. Results showed that SOC decreased up to 61% throughout the soil profile. Mineral-associated organic matter had the highest proportion (more than 75%) of SOC in agricultural soils. The mean value of C/N reduced in mineral-associated organic matter compared to that of bulk soil, which indicates nitrogen concentration in this fraction. The study of soil properties suggested that calcium carbonate equivalent (CCE) could explain SOC content in calcareous soils, while extracted metals (iron, magnesium, and calcium) had a significant relationship with the organic carbon content of heavy fraction.

The purpose of this study was to predict the percentage and yield of chamomile essential oils using the artificial neural network system based on some soil physicochemical properties. Several habitats of chamomile cultivation were investigated and 100 soil samples were shipped to the greenhouse. The maximum and minimum of pH, EC, K, OM (organic matter), CCE (calcium carbonate equivalent), and clay in soils were 8.75-7.94, 1.6-1.0, 381-135, 2.30-0.22, 69-16, and 55.6-32.0, respectively. Growth indices, essential oil percentage, and yield were measured. Artificial neural network modeling was carried out to predict the essential oil concentration and yield using three groups of soil properties as a predictor: 1- nitrogen (N), phosphorus (P), potassium (K), and clay; 2- pH, EC, organic matter (OM) and clay; 3- CCE, clay, silt, sand, N, P, K, OM, pH, and EC. So, three pedotransfer functions (PTFs) were developed using the multi-layer perceptron (MPL) with Levenberg-Marquardt training algorithm for estimating chamomile essential oil content. Results evaluation of the accuracy and reliability of showed that, the third PTF (PTF3) which developed by all independent variables had the highest accuracy and reliability. Results also showed that, it is possible to predict the concentration and yield of chamomile essential oil based on soil physicochemical properties. This issue is important in terms of land suitability, identify areas susceptible to chamomile cultivation and planning for essential oil yields.

Measuring pH of soil samples (at four to five depths down to 300 mm) collected three times from a long-term (16 years) field trial involving annual application of six forms of phosphate fertilizers at the rate of 30 kg P ha−1 yr−1 showed that soil acidity in all treatments, including the untreated control, increased with time. The rates of acidification (pH unit yr−1 during the first 10 years) in the topsoil (0–75 mm depth) were in the order, diammonium phosphate (0.038)>control, single superphosphate>Jordan partially acidulated phosphate rock (JPAPR)>North Carolina partially acidulated phosphate rock (NCPAPR), Jordan phosphate rock (JPR)>North Carolina phosphate rock (NCPR) (0.010). Of the 480 kg P ha−1 applied over the 16 year period, 71 and 57% of P from NCPR and JPR dissolved. The theoretical liming values derived from the dissolution of NCPR and JPR were 1698 and 1303 kg CaCO3 ha−1 respectively. Liming values of the two PRs calculated from the increase in soil pH over control treatment (ΔpH) down to 300 mm soil depth were 640 and 414 kg CaCO3 ha−1 for NCPR and JPR, respectively. The lower liming values estimated from the ΔpH method is probably due to proton transfer resulting from the secondary reactions of dissolved fertilizer phosphate with soil constituents, the unaccounted liming effect of the PRs below 300 mm soil depth and the lower soil pH buffering capacities measured from a short-term pH titration method used in the estimation of the liming values. The results of this long-term field study showed that continuous use of certain phosphate rocks (PRs) can significantly slow down the rate of acidification in pastoral soils.

This investigation is focused on evaluation of the corrosion behavior of embedded steel bars (SB) into concretes. Conventional and modified concretes with eggshell are prepared. Although the effect of calcium carbonate on mechanical behavior is recognized and reported, their effects as eggshell (ES) particles replacing portions of sand and cement contents are reasonably scarce. Corrosion behavior is evaluated by electrochemical impedance spectroscopy (EIS) and the potentiodynamic polarization technique. Equivalent circuit and porous electrode behavior are also considered. The novelty concerns a promising use of concrete with ES content to maintain corrosion resistance concatenated with reasonable structural properties. For this purpose, three distinct concrete mixtures are proposed, i.e., a reference and two modified concretes. One replaces 10 wt.% with cement and another 10 wt.% with sand content. It is found that porous electrode behavior helps to predict the corrosion mechanism. Finer ES particles in concrete mixture provides a rapidly passivation on rebar. This reflects positively in corrosion current density after long-term immersion. Additionally, an environmentally friendly aspect associated with economical factor constitutes a promise use of the concrete.

Breakfast cereal is one of the common foods for children’s nutrition. It is made from sugar, barley, calcium carbonate, salt, maize, peanuts, molasses, and honey. Therefore, assessing the levels of radioactivity in breakfast cereal is essential for children’s health. Gamma-ray spectrometry NaI(Tl) was used to measure the radiation hazard in ten samples collected from the Iraqi market. The corresponding radiation dose quantities and hazard indices were also calculated. The average concentrations of 226Ra, 232Th, and 40K were found to be 18.195, 20.965, and 796.500 (Bq.kg-1). The annual effective dose equivalent (AEDEin), annual ingestion dose (AID), and the risk of cancer incidence (ELCR) were all seen to be within the accepted levels, except the annual gonadal equivalent dose (AGED). Radiation hazard index values (i.e., Iγ, Iα, and Hin) were noticed to be lower than unity, except Iγ was much higher than the internationally permissible limits for the samples of BGF5, BGF6, and BGF7 recommended by UNSCER2000. Therefore, the study findings reveal that this type of cereal can be considered a safe feeding material for children’s health.

Carbon steel B450C and low-chromium stainless steel SS430 were exposed for 30 days to supersulfated “SS1” cement extract solution, considered as a “green” alternative for partial replacement of the Portland cement clinker. The initial pH of 12.38 dropped since the first day to 7.84, accompanied by a displacement to more negative values of the free corrosion potential (OCP) of the carbon steel up to ≈−480.74 mV, giving the formation of γ-FeOOH, α-FeOOH and Fe2O3, as suggested by XRD and XPS analysis. In the meantime, the OCP of the SS430 tended towards more positive values (+182.50 mV), although at lower pH, and XPS analysis revealed the presence of Cr(OH)3 and FeO as corrosion products, as well the crystals of CaCO3, NaCl and KCl. On both surfaces, a localized corrosion attack was observed in the vicinity of local cathodes (Cu, Mn-carbides, Cr-nitrides, among others), influenced by the presence of Cl− ions in the “SS1” extract solution, originating from the pumice. Two equivalent circuits were proposed for the quantitative analysis of EIS Nyquist and Bode diagrams, whose data were correlated with the OCP values and pH change in time of the “SS1” extract solution. The thickness of the corrosion layer formed on the SS430 surface was ≈0.8 nm, while that on the B450C layer was ≈0.3 nm.

This study provides methodological aspects on the equivalent dose estimation for travertine samples, namely heated calcium carbonate, using the TL multiple-aliquot additive-dose approach. Large equivalent doses (EDs), within the range 750–1300 Gy, were calculated using the plateau method based on the NTL glow curve. Moreover, a component resolved TL glow-peak analysis was carried out, using the integrated intensity of the NTL glow peaks for the ED estimation after deconvolution based on the OTOR model. Three different TL peaks were used, termed P4, P5 and P6. The integrated intensity of TL glow peak P4 resulted in age overestimation (15–26%), compared to the age provided using the plateau method. This overestimation could be attributed to the fact that the temperature range of P4 does not coincide with the plateau region of each sample. Milder overestimation (8–14%) was noticed using the integrated intensity of TL glow peak P6, mostly due to the poor deconvolution resolution. Only the integrated intensity of TL glow peak P5 after deconvolution provides ED values compatible with those yielded using the plateau method, with good accuracy. The present study suggests not using the TL intensity (neither in terms of integrated intensity nor of peak height intensity) for ED estimation; instead it is highly recommended to use either the plateau method, or alternatively integrated intensity of TL peak P5 after deconvolution. Unfortunately, using the peak height of TL P5 is not recommended, due to overlapping with P6.

Waste recycling and reuse is an important component of sustainability. Extensive research is being conducted to address this issue by incorporating industrial by-product such as steel slag, copper slag, fly ash, ferro-chrome slag, and so on into the construction industry. Steel slag, which is mostly calcium carbonate, is created as a by-product of the steel oxidation process, whereas copper slag is created as a by-product of the metal smelting process and copper refining, with annual production of 12 and 2 million tonnes, respectively. The percentage of aggregates used in concrete is more than 70%, and the augmentation of construction has compelled suppliers and scholars to use alternate aggregate materials that could protect natural resources and the environment. Various studies on the possible use of copper and steel slag in concrete have been conducted in the literature, but studies using a combination of copper and steel slag including ecological and environmental aspects are few. The objective of this investigation is to produce concrete by replacing fine aggregate and coarse aggregate with copper slag and steel slag. After 7, 28 and 56 curing days, the mechanical properties of the various proportions were found and an analogy was drawn with conventional concrete. The experimental findings reveal that the concrete blend with 75% and 25% replacement of fine and coarse aggregate with copper and steel slag, respectively, shows better results in comparison with other mixes. This mix provides 48% lesser cost than control concrete and has 34.9% less embodied carbon dioxide emission, and hence it is recommended as most sustainable and cost-effective concrete. Utilization of copper slag and steel slag in making this sustainable concrete blend will pave path to a safe environment and protection of natural resources.

This study compares corrosion activities of carbon steel B450C and SS 430 (Mn in low content) exposed for 30 days in cement extract solution. Iron oxide and hydroxide were formed as corrosion products, in addition to CaCO3, in the presence of Cr2O3 on SS 430. Because of the decrease in pH, B450C lost the passive state when OCP shifted to negative values, while SS 430 showed positive OCP values, maintaining its passive state. The SEM images confirmed that the corrosion attack on the surface was less aggressive for SS 430. The Nyquist plots of EIS initially showed capacitive behavior and later changed to semi-linear diffusion impedance, which SS 430 maintained firmly. The phase angle Bode diagrams confirmed these changes. Two equivalent circuits were applied. The calculated values of Rp for SS 430 increased over time (protective passive layer mainly of Cr2O3 oxide), while for carbon steel, Rp reached maximum value after 168 h and then decreased, maintaining minimum values approximately five orders lower than those of the stainless steel.