Ca Concentration Research Articles

Organic matter is a predominant control on total mercury concentration of near-surface lake sediments across a boreal to low Arctic tundra transect in northern Canada

Mercury (Hg) is a bioavailable and toxic element with concentrations that are persistently high or rising in some Arctic and subarctic lakes despite reduced atmospheric emissions in North America. This is due to rising Hg emissions to the atmosphere outside of North America, enhanced sequestration of Hg to sediments by climate-mediated increases in primary production, and ongoing release of Hg from terrestrial reservoirs. To evaluate the influence of organic matter and other parameters on Hg accumulation in northern lakes, near-surface sediments were sampled from 60 lakes across a boreal to shrub tundra gradient in the central Northwest Territories, Canada. The organic matter of the lake sediments, assessed using programmed pyrolysis and petrology, is composed of a mixture of terrestrial, aquatic, and inert organic matter. The proportion of algal-derived organic matter is higher in sediments of lakes below treeline relative to shrub tundra sites. Total sedimentary Hg concentration is correlated to all organic matter constituents but is unrelated to latitude or lake position below or above treeline. The concentrations of Ag, Ca, P, S, U, Ti, Y, Cd, and Zn are also strong predictors of total sedimentary Hg concentration, indicating input from a common geogenic source and/or common sequestration pathways associated with organic matter. Catchment area is a strong negative predictor of total sedimentary Hg concentration, particularly in lakes above treeline, possibly due to retention capacity of Hg and other elements in local sinks. This research highlights the complexity of controls on Hg sequestration in sediment and shows that while organic matter is a strong predictor of total sedimentary Hg concentration on a landscape scale and across extreme gradients in climate and associated vegetation and permafrost, other factors such as catchment area and sources from mineralized bedrock are also important.

Comparative Effects of Calcium, Boron, and Zinc Inhibiting Physiological Disorders, Improving Yield and Quality of Solanum lycopersicum.

Localized calcium deficiency at the tomato flower end causes a physiological disorder called blossom end rot, resulting in yield losses of up to 50 percent. Fruit cracking is another physiological disorder of tomatoes that most often occurs when the movement of water and solutes to the tomato is protracted or rapid, but the underlying cause of fruit cracking is, again, calcium deficiency. Therefore, the present field experiment was conducted with the aim of increasing yield and reducing physiological disorders in tomatoes with a foliar application of calcium and micronutrients (zinc and boron). Four levels of calcium (0, 0.3, 0.6, and 0.9%), three levels of boron (0, 0.25, and 0.5%), and three levels of Zinc (0, 0.25, and 0.5%) were applied foliarly three times (starting at flowering, the 2nd application was repeated when the fruits set, and the 3rd after a period of 15 days from the fruits set). An addition of 0.6% calcium increased yield and associated traits with a decreased flower drop. Likewise, a 0.9% calcium addition increased fruit Ca content and decreased blossom end rot, fruit cracking, and Zn content. Foliar spraying with 0.25% boron (compound B) improved flowering and production while reducing flower drop and tomato fruit cracking. Similarly, an application of 0.5% B significantly increased Ca and B content with minimal blossom end rot and Zn content. Likewise, a 0.5% Zn application resulted in yield and yield-related traits with increased fruit B and Zn contents while blossom end rot, fruit cracking, and fruit Ca content were lower when 0.5% of foliar Zn was applied. Therefore, it is concluded that a foliar application of Ca, B, and Zn can be used alone or in combination to minimize the physiological disorders, increase production, and improve tomato fruit quality.

Low-temperature dechlorination methods for pyrolysis oil of municipal plastic waste

Pyrolysis oil produced from municipal plastic waste can be utilized as fuel and various valuable chemicals as an alternative to petroleum. However, pyrolysis oil usually contains a relatively high concentration of chlorinated compounds, obstructing its utilization in the chemical industry. The present research reveals that pyrolysis oil contains inorganic chlorine and organochlorine compounds, and differentiated approaches should be considered to remove Cl from covalent and ionic chlorine linkages. Transition metal-based ZSM-5 catalysts showed remarkable dechlorination performance via mild C-Cl cracking of 1-chlorooctane and 4-chlorotoluene at 180 °C or below. The neutralization method of mixing pyrolysis oil with an alkaline solution quickly eliminated ionic chlorine from inorganic chlorine compounds, reducing Cl concentrations by up to 70 % at temperature below 40 °C. Based on the different dechlorinating pathways, an ideal combination of these two methods was suggested to enhance chlorine removal efficiency from pyrolysis oil.

International Simple Glass (ISG) dissolution rate in a (Si, Ca)-rich environment at 90 °C and alkaline conditions

The dissolution of International Simple Glass (ISG) was investigated at 90 °C and alkaline conditions with various concentrations of dissolved Si and Ca to unravel the combined effects of those elements on ISG reactivity. Experiments were conducted over durations ranging from 20 days to 3 months. Through morphological, structural, and chemical characterizations, the glass dissolution rate was proven to be strongly correlated with the activity of dissolved silica in the solution. While dissolved calcium did not significantly impact the dissolution rate, precipitation of calcium silicate hydrates (CSH) during the experiments enhanced ISG dissolution rate, though to a modest extent. The 3-months experiments highlighted the strong correlation between the dissolution mechanism and the evolution of the nature of secondary phases in saturated solution. During the first 20 days and at high Si and Ca concentrations, CSH precipitated and aggregated, without preventing the passivating impact of the gel layer at the surface of the glass: the dissolution was controlled by diffusion. Then, a resumption of dissolution occurred between 19 days and 76 days, corresponding to the CSH growth, and a possible mechanistic switch to a hydrolysis-controlled reaction rate. Finally, in some experiments, a drop in pH due to carbonate precipitation was observed along with a decrease in the dissolution rate, falling back in a diffusion-limited regime. Overall, this study shows that at 90 °C, pH = 10 and concentrations of SiO2(aq) exceeding 50 % of saturation with respect to amorphous silica, irrespective of Ca concentration but in presence of CO2(aq), ISG exhibits a very good chemical durability.

Evaluating the effect of cupric sulphate on morphogenic structure induction and plant regeneration in spring barley anther culture in vitro

Aim. Investigation was aimed to ascertain possibility to increase the efficiency of spring barley haploid production in anther culture in vitro by addition of cupric sulphate to the solution for cut tiller cold pretreatment and by increase of cupric sulphate concentrations in the media for morphogenic structure induction and plant regeneration. Methods. Cut tillers were cold pretreated for 5 days at 4ºC in water and in the solutions contained 5 µM and 10 µM of cupric sulphate. Isolated anthers were cultivated on agar solidified nutrient medium containing N6 macro-and MS micronutrients, physiologically active substances, maltose (9.0 %) and on the media with increased (10 µM) content of cupric sulphate. Results. No effect of cupric sulphate addition on cut tiller viability and morphogenesis in anther culture in vitro was found. The lowest plant regeneration frequency was obtained when cupric sulphate was added both to inductive and regenerative media. Сonclusions. Addition of cupric sulphate to the pretreatment solution as well as increase of this microelement concentration (up to 10 µM) in the nutrient media can’t be considered as the methodological approach suitable to enhance the efficiency of spring barley haploid production in anther culture in vitro.

PVC Dechlorination for Facilitating Plastic Chemical Recycling: A Systematic Literature Review of Technical Advances, Modeling and Assessment

Polyvinyl chloride (PVC) resins are widely used in modern society due to their acid and alkali resistance, low cost, and strong insulation properties. However, the high chlorine (Cl) content in PVC poses significant challenges for its recycling. This study reviews the treatment processes, model construction, and economic and environmental assessments to construct a methodological framework for the sustainable development of emerging dechlorination technologies. In terms of treatment processes, this study summarizes three types of processes, pretreatment, simultaneous dechlorination during chemical recycling, product purification, and emphasizes the necessity of dechlorination treatment from a systematic perspective. Additionally, the construction of models for dechlorination processes is investigated from the laboratory to the industrial production system to macro-scale material, in order to evaluate the potential inventory data and material metabolism behaviors. This review also summarized the methodology framework of Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA), which can be applied for evaluation of the economic and environmental performance of the dechlorination processes. Overall, this review provides readers with a comprehensive perspective on the state-of-the-art for PVC dechlorination technologies, meanwhile offering sustainable guidance for future research and industrial applications of chemical recycling of PVC waste.

The precipitation mechanisms of scheelite from CO2-rich hydrothermal fluids: Insight from thermodynamic modeling

Scheelite and wolframite are two main tungsten-bearing ore minerals in tungsten deposits. Compared to wolframite formed mostly by NaCl–H2O fluids, scheelite in many but not all tungsten deposits is associated with CO2–bearing hydrothermal fluids, but its precipitation mechanisms from these fluids are poorly understood. The replacement of wolframite by scheelite is common among tungsten deposits where these two tungstates coexist, but how CO2, as the pH-buffering agent, affects their replacement remains unclear. To answer these questions, we first tested the pH-buffering effect of CO2 by comparing available experimental pH values of H2O–CO2±NaCl solutions at 200–280 °C and the corresponding thermodynamic modeling results. The mean absolute errors between the calculated and experimental pH values are 0.14 log units in H2O–CO2 solutions and 0.13 log units in H2O–CO2–NaCl solutions, indicating that the calculated acitivities of H+ in CO2-bearing solutions are reliable. Then, the solubilities of scheelite, scheelite-ferberite, and scheelite-hübnerite in NaCl–H2O–CO2 systems were modeled in this study. Our modeling results suggest that scheelite solubility in CO2-rich fluids is highly dependent on fluid pressure but is insensitive to fluid temperature. A decrease in fluid pressure from lithostatic to hydrostatic levels at a depth of 3–8 km causes CO2 escape and pH rise and precipitates over 70 % of tungsten contents in fluids on average. Therefore, CO2 escape is an efficient mechanism for precipitating scheelite from CO2–rich hydrothermal fluids. The independence of scheelite solubility on temperature at high pressures and the slightly retrograde solubility at low pressures allows CO2–rich hydrothermal fluids to carry a great amount of tungsten far away from its sources. This may be one of reasons why some scheelite deposits occur at greater distances (>500 m) from the granite or extend along its strike for several kilometers. Similar to the cases in NaCl–H2O systems, two mechanisms for scheelite replacing wolframite in CO2–rich fluids are identified, a single decrease in fluid pressure or simple cooling plus an increase in the ratios of total Ca contents to total Fe (or Mn) contents in fluids.

Biodiesel production, calcium recovery, and adsorbent synthesis using dairy sludge

Dairy sludge (DS) consists of organic compounds such as lipids and valuable inorganic elements. Biodiesel recovery from dairy sludge extract (DSE), using conventional acid (trans)esterification yielded only 16.5 wt%. In contrast, non-catalytic (trans)esterification generated a substantially higher biodiesel yield of approximately 74.0 wt% due to the method’s tolerance for impurities. Defatted dairy sludge (DDS) contained a higher Ca concentration than DS. DDS-produced biochar (DDSB) increased its Ca concentration predominantly in the form of CaO. 91.1% of the Ca was recovered from the DDSB containing Ca. The Ca remaining in the biochar residue (DDSBR) after Ca recovery was in the form of CaCO3. The porous structure developed as the Ca dissolved, implying that DDSBR could be an effective pollutant adsorbent. In this study, a method is proposed to maximize the utilization of DS by producing biodiesel, recovering Ca content, and using it as a pollutant adsorbent.

The significance of calcium and magnesium content in drinking water for arterial stiffness among residents of the Slovak Republic

ABSTRACT Arterial stiffness (AS) is a significant risk factor for cardiovascular diseases, which are the leading cause of death in developed countries. Based on the measurement of AS among residents supplied with soft drinking water (100 respondents) and hard water (100 respondents), a significant difference was found in the pulse wave velocity (PWVao), arterial age, and the difference between arterial and actual age (delta – Δ age). Among respondents consuming soft drinking water, PWVao was higher by 1.9 m s−1, arterial age was higher by 23 years, and Δ age was higher by 14.5 years. As an intervention, originally soft drinking water was treated to increase calcium (Ca) and magnesium (Mg) content by approximately 10–15 mg l−1. After 18 months of consuming water with elevated Ca and Mg content, PWVao decreased by 0.93 m s−1, arterial age decreased by 10.42 years, and Δ age decreased by 11.79 years among respondents originally consuming soft drinking water. Thus, their risk of developing CVD was significantly reduced.

Late Holocene geochemical signature of inter reef mixed sediments on the northeastern Brazilian outer shelf

The northeastern outer shelf in Brazil is a complex ecotone that holds significant information on Holocene sedimentary processes and evolution. X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) were employed to investigate bioclastic sedimentary facies and patches of relict siliciclastic sands. Radiocarbon dating (AMS) indicates that the carbonate sediments and corals formed in the past millennium. The sediment samples were divided into two groups using a multivariate analysis of XRD and XRF. The first group consists of siliciclastic materials, characterized by Si, Al, Fe, K, Zr, and Ti, and has low levels of carbonate and organic matter. The second, bioclastic and mixed facies, has a high carbonate content and exhibits elevated concentrations of Ca, Sr, and Mg, indicating authigenic processes. The EDS data revealed that the shells predominantly consisted of Cl, Cu, Al, Fe, and Ca. The terrigenous sites are detached from the coastal sources and are mainly located within the reef areas of the outer shelf. The erosion processes in these areas were inefficient to eliminate the siliciclastic sediments. This deposit trapped in inter reef sediments holds the key to understanding the timing and interactions between past coastal processes, shelf valley incision, and reef evolution during the Late Holocene transgression.

Geochemical characteristics of olivine and clinopyroxene in parental mafic–ultramafic rocks from the Yuanshishan Ni-Co laterite deposit in Qinghai Province, NW China

Yuanshishan is a Ni-Co laterite deposit that occurs in the Lajishan tectonic zone of the South Qilian orogenic belt, NW China. Ni–Co mineralization took place during the weathering of the parental mafic–ultramafic rocks. Little is known about the petrogenesis of these parent rocks. Therefore, field and petrographic investigations, together with in situ major and trace element analyses, were carried out on olivine and clinopyroxene from unweathered mafic–ultramafic rocks in the Yuanshishan Ni-Co deposit. The results show that olivine (Ni 963–2674 ppm, Co 52.7–245 ppm) is richer in Co and Ni than clinopyroxene (Ni 155–203 ppm, Co 23.1–32.5 ppm) in the Yuanshishan mafic–ultramafic rocks. The chromite (Ni 98.8–892 ppm, Co 836–1062 ppm) show higher Co and Ni than clinopyroxene, but has lower Ni but higher Co than olivine. Therefore, olivine and chromite are two main Co and Ni rich minerals in the parent rocks of Yuanshishan. A compositional comparison of olivine and clinopyroxene from the Yuanshishan deposit to those from other magmatic sulfide deposits reveals that the Yuanshishan parent magma is relatively poor in Ni and rich in Co. Olivine in the dunite of Yuanshishan has a quite high Fo value (95.2–98.3). The Yuanshishan olivine grains also show a positive correlation between Ni content and Ni/Co or Co content, and the correlation with Fo value is not obvious. The Co content shows a negative correlation with the Ni content and Fo value, which are consistent with the mantle olivine characteristics. Furthermore, the Li, Sc, V contents in olivine are lower than 10 ppm, indicating that the magma originated from the mantle. The Al, Si, Ti, Ca, and Na contents in clinopyroxene indicate that the original magma may have been subalkaline basaltic melt. Using an olivine-spinel thermometer, the Yuanshishan magma crystallization temperatures are calculated to be 1256–1376 °C. The AlⅣ:AlⅥ ratio (0.7–6.0) and Eu/Eu* value (0.9–1.4) of the clinopyroxene indicate that the Yuanshishan mafic–ultramafic rocks were formed under conditions of low to medium pressure and high oxygen fugacity. Moreover, the geochemical discriminant diagrams of clinopyroxene indicate that these rocks possibly formed in an island arc setting.

Linking recharge water sources to groundwater composition in the Hindon subbasin of the Ganges River, India

Groundwater resources of the densely populated Indo-Gangetic Basin are under increasing pressure, not only from extensive groundwater abstraction, but also from contamination. In this study we aim to better understand how different recharge sources affect the hydrochemical and isotope composition of groundwater. We used the Hindon subbasin in Northern India as a case study. Recharge water sources and groundwater were analysed for hydrochemical variables and stable isotopes along a 50 km transect between the Yamuna and Ganges rivers. Groundwater samples were statistically clustered based on hydrochemical variables, and the spatial variation of the groundwater clusters was compared with recharge sources.Groundwater quality could be linked to both recharge from irrigation canal water as well as recharge from polluted river water of the Hindon and its tributaries. We could not directly link groundwater outside these related zones to their recharge source. However, we suspect that shallow polluted groundwater (< 40 m depth) is affected by recharge from agricultural areas and infiltration of municipal wastewater, whereas deeper unpolluted groundwater (40–80 m depth) originates from recharge by rain and river water under more pristine conditions. Our findings show that human activities significantly impact the quality of groundwater, as we found vertical recharge of clean irrigation canal water and polluted municipal, agricultural and river surface water (up to 40 m depth). At one location, groundwater at 75 m depth shows increased Cl, NO3 and SO4 concentrations, suggesting accelerated downward displacement of polluted shallow groundwater by pumping. Limited horizontal displacement was found. We present a conceptual model demonstrating the evolution from a previously unpolluted groundwater system discharging to the river, to a contemporary system with infiltration dominance of polluted river, municipal and agricultural water and local clean irrigation canal water. This model may be relevant for large parts of the Indo-Gangetic Basin.

Influence of Spring Burns on the Properties of Humus Horizon of Chernozem in the Southeast of Western Siberia

On the example of soils of the Basic Experimental Complex of the Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences (Tomsk), the influence of spring grass burns on the properties of the upper layer of the humus horizon of Chernozems. In the areas that burned two months ago, 1, 2, 3 and 11 years ago, a total of 56 samples (5–9 replicates) were collected. We found a considerably high stability of the controlled properties of soils (cationic-anionic composition of water extract, content of grain-size fractions and mobile compounds of a wide range of elements, total C and N, organic carbon, pH value, basicity from carbonates) to pyrogenic effects from spring grass fires. Informative indicators reflecting a significant pyrogenic impact over the past 11 years were the content of mobile Ca, Mg and Sr, as well as water-soluble Mg2+ and basicity from carbonates. Their content is higher in the soils of young (0–3 years) burnt areas relative to the old (11 year old) burnt areas and unburnt areas. Among the studied parameters, the pH value, the content of mobile Ba and Sr, and grain-size fractions of 1–5, 5–10, and 10–50 µm, had the low coefficient of variation (20%), and content of water-soluble ammonium and mobile Li and Zn had the high coefficient of variation (70%).

Higher Plasma Copper Exposure was Adversely Associated with Skeletal Muscle Indicators in Chinese Children Aged 6-9 Years: A Cross-Sectional Study.

It is unclear whether blood concentrations of copper (Cu), magnesium (Mg), and calcium (Ca) influence skeletal muscle mass and strength in children. We aimed to explore the associations between plasma Cu, Mg, and Ca and skeletal muscle indicators in Chinese children. A total of 452 children aged 6 to 9 years old were recruited for this cross-sectional study. Whole body lean soft tissue mass (WLSTM), trunk lean soft tissue mass (TLSTM), and appendicular skeletal muscle mass (ASMM) were measured using dual-energy X-ray absorptiometry. Parameters of these indicators divided by Height2 (Ht2) and Weight (Wt) at the corresponding sites were calculated. Handgrip strength was also measured. Parameters of skeletal muscle indicators and handgrip strength that were below the sex-specific 20th percentile were considered low levels. Plasma concentrations of Cu, Mg, and Ca were measured using ICP-MS. After adjusting for several potential covariates, among the total subjects, for every one standard deviation increase in Cu concentrations, there was a 0.939% decrease in WLSTM/Wt, a 0.415% decrease in TLSTM/Wt, and a 0.47% decrease in ASMM/Wt. For every one standard deviation increase in Cu concentrations, there was a higher odd (OR: 1.36, 95%CI 1.06, 1.75) of low WLSTM/Wt, TLSTM/Wt (OR: 1.33, 95%CI 1.03, 1.71), ASMM/Ht2 (OR: 1.32, 95%CI 1.02, 1.69), as well as ASMM/Wt (OR: 1.56, 95%CI 1.23, 1.99). No significant associations were found between Mg, Ca, and most skeletal muscle indicators. Higher plasma Cu concentrations were adversely associated with skeletal muscle indicators at multiple sites in Chinese children.

The effect of various Sn and Ca equal proportional addition on the microstructure, mechanical behavior and corrosion performance of Mg alloys

In the present study, the effects of various Sn and Ca equal proportional addition (0.3:0.1, 0.6:0.2, 1.2:0.4, wt%) on the microstructure, mechanical properties and corrosion behavior of Mg-Sn-Ca alloys were systematically investigated. With the increase of Sn and Ca content, microstructure uniformity of the Mg-Sn-Ca alloy was improved, the average grain size was refined (from 34.4 μm to 21.62 μm, 13.47 μm), and more CaMgSn phases were generated (from 0.39 % to 1.64 %, 4.53 %). With increasing Sn and Ca content, the tensile yield strength (TYS) and ultimate tensile strength (UTS) of Mg-Sn-Ca alloys were gradually increased (TYS: from 91.8 MPa to 98.24 and 125.05 MPa; UTS: from 187.48 MPa to 190.73 and 214.58 MPa), mainly due to the contribution of grain refinement. The electrochemical tests revealed that the corrosion resistance of the Mg-Sn-Ca alloy initially decreases and then increases with the increase of Sn and Ca contents. The hydrogen evolution volume of Mg-0.3Sn-0.1Ca alloy was 41.91 mL cm−2, and the corrosion current density was −1.54 × 10−3 A/cm2. As for Mg-0.6Sn-0.2Ca alloy, deteriorated corrosion resistance compared to the Mg-0.3Sn-0.1Ca alloy was mainly ascribed to the micro-galvanic corrosion between the CaMgSn phase and Mg-matrix. The Mg-1.2Sn-0.4Ca alloy had the best corrosion resistance, with the lowest hydrogen evolution volume of 34.09 mL cm−2 and a minimum current density of −1.15×10−3 mA cm−2, its high corrosion resistance could be attributed to the grain refinement and homogenous distributed CaMgSn phase and more generated Ca(OH)2 product film with dense-structure.

Geothermal ecosystems on Mt. Erebus, Antarctica, support diverse and taxonomically novel biota.

Mt. Erebus, Antarctica, is the southernmost active volcano in the world and harbors diverse geothermally unique ecosystems, including 'Subglacial' and 'Exposed' features, surrounded by a vast desert of ice and snow. Previous studies, while limited in scope, have highlighted the unique and potentially endemic biota of Mt. Erebus. Here, we provide an amplicon-based biodiversity study across all domains of life and all types of geothermal features, with physicochemical and biological data from 48 samples (39 Exposed and 9 Subglacial) collected through various field seasons. We found potentially high taxonomic novelty among prokaryotes and fungi, supporting past hypotheses of high endemism due to the distinctive and isolated environment; in particular, the large number of taxonomically divergent fungal sequences was surprising. We found that different site types had unique physicochemistry and biota; Exposed sites were warmer than Subglacial (median: 40 vs 10°C for Exposed and Subglacial, respectively) and tended to have more photosynthetic organisms (Cyanobacteria and Chlorophyta). Subglacial sites had more Actinobacteriota, correlated with greater concentrations of Ca and Mg present. Our results also suggest potential human impacts on these remote, highly significant sites, finding evidence for fungal taxa normally associated with wood decay. In this study, we provide a blueprint for future work aimed at better understanding the novel biota of Mt. Erebus.

Carbonation resistance of alkali-activated GGBFS/calcined clay concrete under natural and accelerated conditions

The carbonation resistance of alkali-activated materials (AAMs) is a crucial parameter for their applicability in concrete construction, yet the parameters influencing it are insufficiently understood to date. In the present study, the carbonation resistance of alkali-activated concretes with varying fractions of ground granulated blast furnace slag (GGBFS) and calcined clay (i.e., high, intermediate, and low Ca contents) were assessed under natural and accelerated conditions. Corresponding hardened AAM pastes were studied using X-ray diffraction, thermogravimetry, Raman microscopy, and mercury intrusion porosimetry. The carbonation resistance of the concretes at natural CO2 concentration depended principally on their water/(CaO + MgOeq + Na2Oeq + K2Oeq) ratio. The remaining variability for similar ratios was caused by differences between the pore structures of the AAMs. For concrete with favorable water/(CaO + MgOeq + Na2Oeq + K2Oeq) ratio and pore structure, the carbonation resistance was comparable to that of Portland cement concrete. The relationship between carbonation coefficients obtained under accelerated and natural conditions differed for concretes with high and low fractions of calcined clay, indicating that accelerated carbonation testing is less suitable to study the carbonation of low-Ca AAMs.

Potential of kaempferol and caffeic acid to mitigate salinity stress and improving potato growth

Salinity stress adversely affects plant growth by disrupting water uptake, inducing ion toxicity, initiating osmotic stress, impairing growth, leaf scorching, and reducing crop yield. To mitigate this issue, the application of kaempferol (KP), caffeic acid (CA), and plant growth-promoting rhizobacteria (PGPR) emerges as a promising technology. Kaempferol, a flavonoid, protects plants from oxidative stress, while caffeic acid, a plant-derived compound, promotes growth by regulating physiological processes. PGPR enhances plant health and productivity through growth promotion, nutrient uptake, and stress mitigation, providing a sustainable solution. However, combining these compounds against drought requires further scientific justification. That’s why the current study was conducted using 4 treatments, i.e., 0, 20 µM KP, 30 μM CA, and 20 µM KP + 30 μM CA without and with PGPR (Bacillus altitudinis). There were 4 replications following a completely randomized design. Results showed that 20 µM KP + 30 μM CA with PGPR caused significant enhancement in potato stem length (14.32%), shoot root, and leaf dry weight (16.52%, 11.04%, 67.23%), than the control. The enrichment in potato chlorophyll a, b, and total (31.86%, 46.05%, and 35.52%) was observed over the control, validating the potential of 20 µM KP + 30 μM CA + PGPR. Enhancement in shoot N, P, K, and Ca concentration validated the effective functioning of 20 µM KP + 30 μM CA with PGPR evaluated to control. In conclusion, 20 µM KP + 30 μM CA with PGPR is the recommended amendment to alleviate salinity stress in potatoes.

Biochars from chlorine-rich feedstock are low in polychlorinated dioxins, furans and biphenyls

Chlorinated aromatic hydrocarbons like polychlorinated dibenzo-p-dioxins and -furans (PCDD/F) and polychlorinated biphenyls (PCB) are omnipresent in the environment due to historic production, use, and (unintended) release. Nowadays, their emission and maximum concentration in environmental compartments is strictly regulated. During biochar production, PCDD/F and PCB may be formed and retained on the solid pyrolysis product. Industrial biochars certified, e.g., under the European Biochar Certificate (EBC), exhibit concentrations that were always well below threshold values for soil application and even animal feed. However, this has not been sufficiently tested for chlorine (Cl) rich organic material such as marine biomass or polyvinyl chloride (PVC) contaminated feedstock. Here, we analyzed PCDD/F and PCB contamination in biochars produced at different temperatures from different biomasses with comparatively high Cl contents in the range from 0.2 % to 3.8 % (w/w, seagrass, two types of saltwater macroalgae, tobacco stalks, and PVC contaminated wood). All of the biochars produced showed PCDD/F and PCB contents well below the applicable threshold values given by the EBC (< 20 ng TEQ kg−1 for PCDD/F and < 2×105 ng kg−1 for PCB). The EBC thresholds were undershot by a minimum of factor 1.5 for PCDD/F (mostly factor 20) and by a minimum of factor 90 for PCB. Between 1 and 27 ppb of feedstock Cl were transformed to Cl bound in PCDD/F and PCB in the biochars. No consistent correlation between biomass Cl contents and contents of PCDD/F and PCB were found but higher Cl contents in the feedstock led to a more diverse PCDD/F congener pattern in the biochars. Pyrolysis of PVC-amended wood resulted in consistently higher contamination of PCDD/F and PCB in the biochars compared to pyrolysis of the other biomasses, potentially due to differences in Cl speciation in the feedstocks i.e., Cl in PVC is already covalently bound to an organic carbon backbone. A high contamination in PCDD/F and PCB in biochar was intentionally triggered by separation of pyrogas and biochar in the reactor at < 300 °C to promote condensation of contaminants on the solid product. Between 20 % and 80 % of feedstock Cl was released via the pyrogas, i.e., neutralization of HCl in burnt pyrogas might be necessary when pyrolyzing Cl-rich feedstock in industrial biochar production. Our results indicate that biochars produced from Cl-rich feedstocks with proper biochar production process control are conform with European certification guidelines for PCDD/F and PCB contamination. The results open the opportunity to exploit and valorize so far non-used marine or otherwise Cl enriched biomasses for the production of biochar and carbon sinks.

Determination of sodium, chlorine, and bromine concentrations in breast milk using neutron activation: Correlation, regression, and machine learning predictions

Breast milk plays a vital role in infant health, providing essential nutrients that directly impact nutrition and development. Understanding its elemental composition, as well as the relationships among these elements, is crucial for assessing its nutritional adequacy. This study focused on determining the concentrations of sodium (Na), chlorine (Cl), and bromine (Br) in the breast milk of lactating mothers in Tehran, Iran, during early lactation. The primary objectives were to analyze the concentrations of these elements, investigate their interrelationships, and employ machine-learning techniques to predict their concentrations in breast milk. Neutron activation analysis (NAA) was used to precisely measure the levels of Na, Cl, and Br, while statistical methods, including correlation and regression analyses, were applied to further explore these relationships. Machine-learning models, specifically Random Forest and Linear Regression, were utilized to predict the concentrations of these elements based on their interdependencies. The study revealed mean concentrations of 5.12 mg/g for Na, 8.14 mg/g for Cl, and 11.84 mg/kg for Br in the breast milk samples. A strong positive correlation was observed between Na and Cl (r = 0.976, p < 0.001), while moderate positive correlations were found between Na and Br (r = 0.558, p < 0.001) and Cl and Br (r = 0.606, p < 0.001). Multiple regression models showed that 94.7 % of the variance in Na concentration could be explained by Cl and Br levels (R-squared = 0.947), with a strong positive association between Cl and Na, and a slight inverse relationship between Br and Na. A similar model for Cl concentrations showed strong predictive power, with Na being a significant predictor. However, the model for Br concentrations explained a smaller proportion of variance (R-squared = 0.318), suggesting that additional factors influencing Br levels were not captured in this study. Furthermore, multicollinearity was observed between Na and Cl (VIF = 20.675), indicating potential interactions between these elements. This study highlights the significant correlations between Na, Cl, and Br in breast milk, with particularly strong predictive models for Na and Cl concentrations. The findings also suggest the need for further investigation into the factors affecting Br concentrations. Overall, this research provides valuable insights into the elemental composition of breast milk and its implications for infant nutrition and health.