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Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an ecosystem, soil contains myriads of living organisms and it serves as a substrate for humans to obtain their sustenance from plants. Plants derive their nutrients and water from the soil. Soil facilitates the essential requirements for the survival of plants. The health of the soil is crucial for maintaining the overall health of the ecosystem. Healthy soil ensures the sustenance of a thriving ecosystem and facilitates the survival of creatures. As a result of natural or human actions, the characteristics of the soil gets deteriorated and become inhospitable for plant growth and survival. Such soils are considered as problem soils, which include salt-affected, calcareous, acidic, and acid-sulfate soils. To avoid soil degradation and retain its properties, remedial measures including the addition of organic manures, have been implemented. Yet these inputs exhibit a slower recovery rate, and in some cases, they fail to achieve their maximum potential. Due to the growing necessity to mitigate the impacts caused by problem soil, biofertilizers derived from various beneficial microorganisms are regarded as a viable solution. Microbial inoculants, through their biological and chemical interactions, support the maintenance of the ecosystem. Microbial inoculants modify the soil’s characteristics, thereby counteracting the negative impacts of problem soils. This article provides a concise explanation of the impact of chemically problem soils and the contribution of microbial inoculants in enhancing soil characteristics, promoting plant development, and eventually augmenting food supply. [ABSTRACT FROM AUTHOR]

The Paris Agreement to limit global warming to well below 2°C requires drastic reductions in greenhouse gas emissions and the balancing of any remaining emissions by carbon dioxide removal (CDR). Due to uncertainties about the potential and durability of many land-based approaches to deliver sufficient CDR, marine CDR options are receiving more and more interest. We present the current state of knowledge regarding the potentials, risks, side effects as well as challenges associated with technical feasibility, governance, monitoring, reporting and accounting of marine CDR, covering a range of biotic and geochemical approaches. We specifically discuss to what extent a comparison with direct injection of CO2 into seawater, which had been proposed decades ago and is now prohibited by international agreements, may provide guidance for evaluating some of the biotic marine CDR approaches. [ABSTRACT FROM AUTHOR]

Ocean alkalinity enhancement (OAE), one of the marine carbon dioxide removal strategies, is gaining recognition in its ability to mitigate climate change and ocean acidification (OA). OAE is based on adding alkalinity to open-ocean and coastal marine systems through a variety of different approaches, which raises carbonate chemistry parameters (such as pH, total alkalinity, aragonite saturation state) and enhances the uptake of carbon dioxide (CO2) from the atmosphere. There are large uncertainties in both short- and long-term outcomes related to potential environmental impacts, which would ultimately have an influence on the social license and success of OAE as a climate strategy. This paper represents a synthesis effort, leveraging on the OA studies and published data, observed patterns, and generalizable responses. Our assessment framework was developed to predict the sensitivity of marine calcifiers to OAE by using data originating from OA studies. The synthesis was done using raw experimental OA data based on 68 collected studies, covering 84 unique species and capturing the responses of 11 biological groups (calcifying algae, corals, dinoflagellates, mollusks, gastropods, pteropods, coccolithophores, annelids, crustacean, echinoderms, and foraminifera), using regression analyses to predict biological responses to NaOH or Na2CO3 addition and their respective thresholds. Predicted responses were categorized into six different categories (linear positive and negative, threshold positive and negative, parabolic and neutral) to delineate responses per species. The results show that 34.4 % of responses are predicted to be positive (N=33), 26.0 % negative (N=25), and 39.2 % (N=38) neutral upon alkalinity addition. For the negatively impacted species, biological thresholds, which were based on 50 % reduction of calcification rate, were in the range of 50 to 500 µ mol kg−1 NaOH addition. Thus, we emphasize the importance of including much lower additions of alkalinity in experimental trials to realistically evaluate in situ biological responses. However, it is important to note our results do not consider equilibration with the atmosphere and are thus only applicable to short-term and near-field application. The primary goal of the research was to provide an assessment of biological rates and thresholds predicted under NaOH / Na2CO3 addition that can serve as a tool for delineating OAE risks. This will help guide and prioritize future OAE biological research and regional monitoring efforts and will also aid in communicating risks to stakeholders. This is important given the fact that at least some of the current OAE approaches do not always assure safe biological space. With 60 % of responses being non-neutral, a precautionary approach for OAE implementation is warranted, identifying the conditions where potential negative ecological outcomes could happen, which is key for scaling up and avoiding ecological risks. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to evaluate the effect of a solid slow-release carbon source (3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV) on heterotrophic and sulfur autotrophic cooperative denitrification (HAD) of aquaculture wastewater. Batch tests were carried out to analyze the effect of different PHBV/S volume ratios in the range of 30–70% on the denitrification of synthetic aquaculture wastewater under a short hydraulic retention time (HRT). The performance of the HAD process showed that the NO3−-N removal was increased with an increase in the PHBV/S volume ratio. When the PHBV/S ratio reached 70%, the average NO3−-N concentration of effluent was 0.38 mg/L in the stable phase. The variation in pH and alkalinity showed that the average pH value and residual alkalinity were above 7.03 and 57.63 mg/L at the PHBV/S ratio of 50%. Based on the relationship between sulfate generation and nitrate removal under different ratios of PHBV/S, analysis of the proportion of autotrophic and heterotrophic denitrification (HD) showed that sulfur autotraophic denitrification (SAD) was enhanced at a PHBV/S ratio of 50%, and competition for nitrate substrates occurred between autotrophic and heterotrophic at a PHBV/S ratio of 70%. [ABSTRACT FROM AUTHOR]

Ocean alkalinity enhancement (OAE) and direct ocean removal (DOR) are emerging as promising technologies for enacting negative emissions. The long equilibration timescales, potential for premature subduction of surface water parcels, and extensive horizontal transport and dilution of added alkalinity make direct experimental measurement of induced CO2 uptake challenging. Therefore, the challenge of measurement, reporting, and verification (MRV) will rely to a great extent on general circulation models, parameterized and constrained by experimental measurements. A number of recent studies have assessed the efficiency of OAE using different model setups and different metrics. Some models use prescribed atmospheric CO2 levels, while others use fully coupled Earth system models. The former ignores atmospheric feedback effects, while the latter explicitly models them. In this paper it is shown that, even for very small OAE deployments, which do not substantially change atmospheric pCO2 , the change in oceanic CO2 inventories differs significantly between these methods due to atmospheric feedback causing some ocean CO2 off-gassing. An analogous off-gassing occurs during direct air capture (DAC). Due to these feedback effects, care must be taken to compute the correct metrics when assessing OAE efficiency with respect to determining negative emissions credits, as opposed to determining the effect on global temperatures. This paper examines the commonly used metrics of OAE efficiency, their exact physical meanings, the assumptions inherent in their use, and the relationship between them. It is shown that the efficiency metric η(t) , used in prescribed p CO 2atm simulations, equals the equivalent schedule of a gradual DAC removal and storage in a fully coupled system. [ABSTRACT FROM AUTHOR]

Copyright of Special Steel is the property of Daye Special Steel Co. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study compared the supplementation of Litopenaeus vannamei tanks with inoculums generated by different nitrogen sources (NH4Cl or feed). The interactions of inoculums and C/N adjustment strategies on water quality and growth performance were also investigated. After preparation of inoculums, shrimp juveniles were reared for 39 days at 142 shrimps/m3 in four treatments: T1, NH4Cl-based inoculum + heterotrophic C/N adjustment; T2, NH4Cl-based inoculum + mixotrophic C/N adjustment; T3, feed-based inoculum + heterotrophic C/N adjustment; and T4, feed-based inoculum + mixotrophic C/N adjustment. At the end, two-way ANOVA analysis showed significant interactions of time × inoculum or time × C/N adjustment strategy on dissolved oxygen, pH, and settleable solids. Alkalinity was significantly affected by the time × C/N adjustment strategy interaction, while inorganic nitrogen species (TAN, NO2-N, and NO3-N) were altered depending on the time × inoculum effect. Inoculum and C/N adjustment strategy significantly altered alkalinity and TAN levels. TAN levels in T1 and T2 treatments accumulated for 2 weeks, and organic carbon addition was not effective in mitigating high TAN levels. The mixotrophic strategy significantly reduced solids levels, while enhancing DO levels. No significant interactive effects of inoculum × C/N adjustment strategy were detected on the water quality indicators. The final body weight (FBW), feed conversion ratio (FCR), and weekly growth rate (WGR) of shrimp were significantly improved in tanks supplied with feed-based inoculum. Also, the inoculum × C/N adjustment strategy led to significantly higher FBW, weight gain, specific growth rate, and WGR in tanks supplied with feed-based inoculum and heterotrophic C/N adjustment. In conclusion, feed-based inoculum prevented the accumulation/peak of nitrogen species, reduced the nitrification establishment time, and enhanced growth performance. In addition, inoculum effectiveness was affected by the C/N adjustment strategy, highlighting the advantageous performance of mixotrophic approach. This information can develop efficient management practices for biofloc systems. [ABSTRACT FROM AUTHOR]

Despite the advantage of high carbon utilization, CO2 electroreduction (CO2ER) in acid is challenged by the competitive hydrogen evolution reaction (HER). Designing confined catalysts is a promising strategy to suppress HER and boost CO2ER, yet the relationship between the confined structure and catalytic performance remains unclear, limiting rational design. Herein, using Cu2O@mesoporous SiO2 core‐shell catalysts as a well‐defined platform, a volcano‐shaped relationship is found between the thickness of mesoporous SiO2 layer and productivity of multicarbon (C2+) products in CO2 electroreduction. The optimal shell thickness of 15 nm is identified, with in situ spectroscopies and theoretical simulations attributing this to the trade‐off between the local alkalinity and CO2 concentration, arising from the nanoconfinement effect. At this optimal thickness, the Cu2O@ mesoporous SiO2 catalyst achieves a C2+ Faradaic efficiency of 83.1% ± 2.5% and partial current density of 687.8 mA cm−2 in acidic electrolytes, exceeding most reported catalysts. This work provides valuable insights for the rational design of confined catalysts for electrocatalysis. [ABSTRACT FROM AUTHOR]

The capacity of aquatic systems to buffer acidification depends on the sum contributions of various chemical species to total alkalinity (TA). Major TA contributors are inorganic, with carbonate and bicarbonate considered the most important. However, growing evidence shows that many rivers, estuaries, and coastal waters contain dissolved organic molecules with charge sites that create organic alkalinity (OrgAlk). This study describes the first comparison of (1) OrgAlk distributions and (2) acid–base properties in contrasting estuary‐plume systems: the Pleasant (Maine, USA) and the St. John (New Brunswick, CA). The substantial concentrations of OrgAlk in each estuary were sometimes not conservative with salinity and typically associated with very low pH. Two approaches to OrgAlk measurement showed consistent differences, indicating acid–base characteristics inconsistent with the TA definition. The OrgAlk fraction of TA ranged from 78% at low salinity to less than 0.4% in the coastal ocean endmember. Modeling of titration data identified three groups of organic charge sites, with mean acid–base dissociation constants (pKa) of 4.2 (± 0.5), 5.9 (± 0.7) and 8.5 (± 0.2). These represented 21% (± 9%), 8% (± 5%), and 71% (± 11%) of titrated organic charge groups. Including OrgAlk, pKa, and titrated organic charge groups in carbonate system calculations improved estimates of pH. However, low and medium salinity, organic‐rich samples demonstrated persistent offsets in calculated pH, even using dissolved inorganic carbon and CO2 partial pressure as inputs. These offsets show the ongoing challenge of carbonate system intercomparisons in organic rich systems whereby new techniques and further investigations are needed to fully account for OrgAlk in TA titrations. [ABSTRACT FROM AUTHOR]

Algae communities as primary producers are essential elements of aquatic ecosystems and contribute significantly to oxygen production, carbon dioxide fixation, and nutrient transport processes in water bodies. The use of algae-based carbon capture and storage technologies does not produce harmful by-products that require disposal, and the resulting algal biomass can be valuable across various industrial sectors. In this study, model experiments were conducted to develop sequential absorption–microalgae hybrid CO2-capture methods. To facilitate CO2 capture from flue gases, wood biomass ash (WBA), an agricultural by-product, was utilized for its alkaline properties, while the flue gas scrubbing medium was regenerated by algae that restored alkalinity during their growth. In our experiments, one of our goals was to determine the optimal conditions for achieving maximum algal biomass growth in the shortest possible time. The suitability of WBA for flue gas cleaning was tested via simulation of CO2 introduction. Moreover, a method was developed to determine the dissolved inorganic carbon content with the use of an OxiTop device monitoring the changes in pressure. The applied device was a closed, static, and pressure-based respirometer originally designed to determine the biological activity of microorganisms in both solid and liquid samples. In addition, the effects of CO2-enriched WBA extract on algae cultivation were also analyzed, confirming that it imposed no growth inhibition and identifying the concentration (10% WBA) that optimally promoted algal growth. The optimal initial algal concentration and nutrient conditions for maximum growth were also determined. [ABSTRACT FROM AUTHOR]

Ocean alkalinity enhancement (OAE) is a nature-based technology for CO2 removal and storage, but little is known about its environmental safety. We tested a CO2-equilibrated OAE deployment in a close-to-natural community using in situ mesocosms in the oligotrophic subtropical North Atlantic and assessed metazoan zooplankton to inform about food web stability, structure, and production. In addition, a literature review complemented experimental results by summarizing physiological responses of marine animals to decreasing proton concentrations, or increased pH. The food web studied proved resistant, and zooplankton physiologically tolerant, to the OAE tested. We observed short-term effects of OAE on zooplankton reproduction and productivity, which were likely trophically mediated. Yet, these did not affect zooplankton populations or their nutritional value as food for fish. Our study demonstrates an environmentally safe OAE application, but also stresses the risks of more intense OAE options, and the vulnerabilities of other marine ecosystems. [ABSTRACT FROM AUTHOR]

Context: Salt stress is one of the major, ever-increasing abiotic stresses that hinders rice production across arable land around the world. In order to sustain the production of rice (Oryza sativa) in these salt-affected areas, high-yielding stable salt tolerant genotypes must be identified. Aims: The additive main effects and multiplicative interaction (AMMI) model was carried out to identify high-yielding stable rice genotypes under both saline and alkali stress. Methods: Nineteen promising rice genotypes including five standard checks were evaluated using randomized block design under nine salt stress environments using three replications in 2017 and 2018. Key results: The AMMI model II is thought to be the best model for genotype identification based on prediction accuracy with high GEIS and low GEIN (genotype and environment interaction noise). According to AMMI model II, six genotypes were identified as the top performers under salt stress: one genotype (CSR RIL-01-IR 165) yielded the best in three environments; another genotype (CSR 2711-17) yielded highly in in two environments; and the remaining three genotypes (RP5989-2-4-8-15-139-62-6-9, RP 6188-GSR IR1-8-S6-S3-S1, RP6189-HHZ17-Y16-Y3-SAL1) as well as one control genotype (CHK2) yielded well in single environments. Conclusions: Based on AMMI stability study, genotypes RP5989-2-4-8-15-139-62-6-9, CSR2711-17, CSR RIL-01-IR 165, CSR-2748-4441-195, CSR-2748-4441-193), and CSRRIL-01-IR 75 were determined to be higher yielding and more stable than the national control genotype (CSR23). Implications: The high-yielding stable genotypes identified in this study could be planted for salt-affected areas to sustain the production of rice. Salt tolerant varieties with stable performance can be used to address productivity in salt-affected land. Five rice (Oryza sativa) genotypes (RP 5989-2-4-8-15-139-62-6-9, CSR RIL-01-IR 75, CSR-2748-4441-193, CSR-2748-4441-195, and CSR 2711-17) were highly stable across salt-affected environments with yielded 5% more than the national control genotype (CSR23). These high yielding genotypes identified could be used as potential parental lines for breeding varieties for salt-affected conditions to enhance the productivity of salt-affected soils. This article belongs to the collection: Abiotic Stress Tolerance vs Climate Change. [ABSTRACT FROM AUTHOR]

The current research with title on study on ichthyofaunal diversity and physiochemical assessment of the Baran dam, district Bannu. It was carried out between February to March and May to October 2022. A total of 27 species from 18 genera, 8 families, and 5 orders were gathered. With a percentile range of 81.85%, the cyprinidae family was the most prevalent and abundant, whereas the mastacembelidae family had a lower abundance of 0.92%. After examining their total dissolved solids (TDS), pH, oxygen, hardness, alkalinity, and temperature, the majority of physico-chemical parameters showed substantial regional variation (ANOVA, p < 0.05). Temperature and pH readings, however, did not show any differences between the sampling locations (p > 0.05). [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Salt-alkalization is becoming an increasingly challenging environmental and socioeconomic problem as it considerably reduces crop growth and productivity. However, studies have often skewed towards neutral salinity stress, hence plants' physiological responses to saline-alkalinity remain unclear. Here we unravel this gap by dissecting key physiological responses of rice, using cultivar Hinohikari under salinity stress, alkaline stress and saline-alkaline stress. Our results show that the sensitivity of rice to salt stress is aggravated under high pH than low pH conditions. For example, by day 16 of stress imposition, severe saline-alkalinity (SSA) and severe alkalinity (SA) had reduced shoot dry mass by 370 and 235%, respectively, whereas neutral salinity stress had reduced it by 59% only. Physiologically, saline-alkaline stressed plants were nearly 6 times more chlorotic in younger leaf blades, as a result of a 182% reduction in Fe concentration. In tandem, older leaf blades were 4 times more chlorotic as a result of Na+ toxicity induced senescence by accumulating 727% more Na+ under severe SSA than under salinity stress. This high rhizospheric pH induced Na+ hyperaccumulation was at the expense K+ that leaked excessively in the roots, resulting into improper K:Na balances. Furthermore, SSA exposed plants exhibited compromised membrane integrity particularly in leaves, which was associated with 4 times, and 2.6 times more H2O2 accumulation than control and neutral salinity stressed plants, respectively. These results are consistent with previous reports, and further accentuate the lethality of combined growth media high pH and Na for plant growth, and provides avenues for targeting useful traits for breeding and enhancing plants' tolerance to mixed saline-alkaline stress. Future research should further consider unravelling more on the molecular signatures underlying these physiological responses. [ABSTRACT FROM AUTHOR]

This investigation looked at the ameliorative role of camel whey protein hydrolysates-diet (PH) in Oreochromis niloticus stocked under alkaline conditions. One hundred sixty fish (16.02 ± 0.14 g) were allocated equally into four groups with four replications for 30 days. The first (control) and second (alkaline) groups were fed basal diets and maintained in fresh and alkaline water, respectively. The third and fourth groups were fed on a PH diet (basal diet containing 75 g PH/kg) and maintained in fresh water and alkaline water, respectively. The hematology, immune-antioxidant indices, immune-regulatory genes, histopathological investigation of the spleen, and resistance to Aeromonas sobria were investigated. The results showed that the alkaline condition induced hematological disorders (lowered red blood cells, hemoglobin, packed cell volume, and white blood cell count) and immunosuppression (lowered phagocytic activity and index, lysozyme, nitric oxide, and complement 3) in the exposed fish. Alkaline exposure induced oxidative stress through elevation of the malondialdehyde and reduction in the antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, glutathione S-reductase, and reduced glutathione). The immune modulatory genes (tolls like receptor-5, interleukin-1beta, interleukin-6, interleukin-8, interleukin-10, interleukin-17, nuclear factor kappa beta, and tumor necrosis factor-alpha) were down-regulated by exposure to alkaline conditions. The microscopic section of the spleen of the fish subjected to alkaline conditions showed notable hyperplasia of the melanomacrophage centers, besides vascular congestion, endothelial cell hypertrophy, and mild hypercellularity in the erythroid and lymphoid elements. In addition, few sections manifested more pronounced erythroid hyperplasia than the lymphoid one. The survival of the fish subjected to alkaline conditions was reduced during the A. sobria challenge. Feeding on a PH diet, the hematology was restored and the immune-antioxidant functions were modulated. Modulation of the immune-regulatory genes and increased survivability of the alkaline-exposed fish were noticed when fed on the PH diet. Consequently, we can recommend enriching the Nile tilapia diet with a 75 g PH/kg diet especially when reared under alkaline conditions to support the immune functions of the fish. [ABSTRACT FROM AUTHOR]

• Five boiling point temperatures were conducted for ammonia stripping. • The ammonia removal rate reached 80% during the boiling point stripping process. • Temperature and vacuum mainly affect ammonia nitrogen mass transfer and removal velocity. • The pH and alkalinity mainly affect ammonia nitrogen dissociation and removal rate. • Water evaporation rate affects ammonia stripping efficiency. High ammonia-nitrogen digestate has become a key bottleneck limiting the anaerobic digestion of organic solid waste. Vacuum ammonia stripping can simultaneously remove and recover ammonia nitrogen, which has attracted a lot of attention in recent years. To investigate the parameter effects on the efficiency and mass transfer, five combination conditions (53 °C 15 kPa, 60 °C 20 kPa, 65 °C 25 kPa, 72 °C 35 kPa, and 81 °C 50 kPa) were conducted for ammonia stripping of sludge digestate. The results showed that 80% of ammonia nitrogen was stripped in 45 min for all experimental groups, but the ammonia transfer coefficient varied under different conditions, which increased with the rising of boiling point temperature, and reached the maximum value (39.0 mm/hr) at 81 °C 50 kPa. The ammonia nitrogen removal efficiency was more than 80% for 30 min vacuum stripping after adjusting the initial pH to above 9.5, and adjustment of the initial alkalinity also affects the pH value of liquid digestate. It was found that pH and alkalinity are the key factors influencing the ammonia nitrogen dissociation and removal efficiency, while temperature and vacuum mainly affect the ammonia nitrogen mass transfer and removal velocity. In terms of the mechanism of vacuum ammonia stripping, it underwent alkalinity destruction, pH enhancement, ammonia nitrogen dissociation, and free ammonia removal. In this study, two-stage experiments of alkalinity destruction and ammonia removal were also carried out, which showed that the two-stage configuration was beneficial for ammonia removal. It provides a theoretical basis and practical technology for the vacuum ammonia stripping from liquid digestate of organic solid waste. [Display omitted] [ABSTRACT FROM AUTHOR]

Mineral and rock additions to the environment have been proposed as a pathway to remove atmospheric CO2. This process occurs when hydrated minerals or rocks increase alkalinity, promoting the formation of bicarbonate. In this study, we evaluate the potential of commonly used hydrated rock and mineral powders to enhance alkalinity and react with both atmospheric and concentrated CO2. Silicate minerals and rocks exhibit minimal reactivity with atmospheric CO2 and provide moderate alkalinity enhancement. Volcanic rocks like basalt were shown to release CO2. Ground cement and Mg(OH)2, refined from CO2-free ultramafic rock, significantly increase alkalinity and mineralize both atmospheric and concentrated CO2. However, the effectiveness of cement waste is limit by its variable CaO content and potential heavy metal contributions. Overall, Mg(OH)2, derived from silicates, offers a promising pathway for the removal and storage of CO2. CO2 capture through enhanced rock weathering requires that rock and mineral soil additions promote CO2 to bicarbonate transformation, typically by increasing substrate alkalinity. Here, the authors evaluate the potential of commonly used hydrated rock and mineral powders such as cement waste to enhance alkalinity and react with both atmospheric and concentrated CO2. [ABSTRACT FROM AUTHOR]

Geopolymer concretes have shown better resistance against alkali–silica reaction (ASR) than ordinary Portland cement concretes, which was attributed to the low pore solution alkalinity of the geopolymer. However, the alkalinity of the geopolymer pore solution depends on the concentration and volume of the activating solutions used and age of the geopolymer. The main objective of this study was to investigate the effects of pore solution alkalinity on the ASR expansion of the metakaolin‐based geopolymer concrete. The chemistry of the pore solution of metakaolin‐based geopolymer was studied, and its reaction with reactive and non‐reactive aggregates was investigated. The concrete prism expansion tests showed no ASR‐induced expansion in geopolymer despite sufficient pore solution alkalinity to attack the reactive aggregates. The SEM and XRD characterizations confirmed that no ASR‐related gel was formed during the reaction between reactive aggregates and extracted pore solution. The chemical structure of the reaction product between aggregates and pore solution was characterized using MAS NMR and revealed no difference in the reaction products with reactive and non‐reactive aggregates. The results suggest that the pore solution alkalinity is not the sole governing parameter for ASR expansion in the geopolymer. [ABSTRACT FROM AUTHOR]

Rapid development and deployment of marine carbon dioxide removal (mCDR) approaches will be required to prevent the worst consequences of climate change and meet national treaty obligations under the Paris agreement. However, approaches to monitor the efficacy and environmental safety of mCDR are not being developed with the same intensity as the technology. Verification will be required to convince a sceptical public and regulatory community of the overall benefit of mCDR as well as provide the regulatory community a basis for risk assessments that will be required for at scale deployments. In this perspective, we posit that genomics-based approaches can be used to assess the efficacy of carbon sequestration and monitor for the possibility of unintended consequences. By adopting these approaches, it will be feasible to develop the evidence portfolio necessary to underpin assessments of the risks, benefits and trade-offs involved in responsible deployment of mCDR. [ABSTRACT FROM AUTHOR]

Based on the passivation of iron in alkaline solutions, aqueous alkaline treatment has been taken as an effective desalination technique to increase the stability of archaeological iron. However, chlorides may destroy the passivation of iron artifacts, causing damage to the treated artifacts during desalination. In this study, electrochemical and microstructure analyses were carried out in alkaline solutions with known chloride content, using archaeological iron and pre-corroded iron coupons with varying chloride levels within the rust layer. The study revealed that alkalinity ensures passivation even in the presence of chloride within the rust layer. However, the passivation weakens as the concentration of ‘free’ chloride ions in the alkaline solution increases due to their migration from the rust layer, leading to active corrosion. A chloride threshold value (CTV) of 355 ppm in 0.1 mol/L NaOH solution was established as a chloride level for the replacement of the alkaline solution. The determination of CTV based on electrochemical measurements is intended to guide the timely replacement of the desalination solutions, thereby preventing chloride-induced iron corrosion during desalination treatments. [ABSTRACT FROM AUTHOR]

The rational design of MgO nanomaterials with rich oxygen vacancies has garnered significant attention. However, the influence of oxygen vacancies and alkalinity on the generation and stability of active oxygen, particularly regarding the antibacterial activity of MgO nanomaterials, remains uncertain. In this work, the defective MgO nanoplates with adjustable oxygen vacancy and alkalinity were successfully designed by thermal treatment in different atmospheres (air, vacuum, and N 2). MgO nanoplates calcined in N 2 atmosphere exhibited superior antibacterial activity against Escherichia coli (ATCC 25922), reducing colony counts from 571.5 to 53.5 CFU/mL at 750 μg/mL compared with MgO nanoplates calcined in air. At a low concentration (100 μg/mL), MgO nanoplates calcined in N 2 atmosphere exhibited remarkable antibacterial performance, achieving a colony survival ratio of only 6.8 %. This enhanced performance was correlated with a higher oxygen vacancy (O A) content (51.3 %) in MgO nanoplates calcined in N 2 compared to those calcined in air (26.5 %). Advanced characterization techniques and alkalinity measurements revealed that calcination in a N 2 atmosphere promoted oxygen vacancy formation on the MgO surface, accelerated MgO surface hydrolysis owing to oxygen vacancies, and increased OH− production. Consequently, this process enhances the participation of adsorbed oxygen in surface reaction, leading to the increased generation and stability of active oxygen in an alkaline environment. These findings provide valuable insights into the design of oxygen vacancies and offer a potential approach for constructing highly antibacterial nanomaterials. Such materials could find applications in personal protection and public health. [ABSTRACT FROM AUTHOR]

Carbonate alkalinity (CA) is the major toxic factor that interferes with the survival and growth of shrimp in saline–alkaline water. Gills are the main entry organ for CA toxicity in shrimp. In this study, low-salinity cultured Litopenaeus vannamei were exposed to 5 mmol/L CA stress for 7 days and then recovered for 7 days to explore the physiological changes in the gills under CA stress and recovery conditions at multiple biological levels. The results showed that CA stress increased the activities of antioxidative biochemical indexes (T-AOC, T-SOD, and POD) and the relative expression levels of romo1, nrf2, and gpx genes, while it decreased the relative expression levels of the sod and hsp70 genes. In addition, CA stress also increased the relative expression levels of genes involved in endoplasmic reticulum (ER) stress (bip, ire1, and xbp1), immunity (alf, crus, pen-3 and propo), apoptosis (casp-3), detoxification metabolism (cyp450 and gst), and osmotic adjustment (ca, nka-α, nka-β, vatp, nhe, clc, aqp, tip4, and ccp). Although changes in some of the physiological indexes were reversed after the CA stress was relieved, they still could not effectively recover to the control level. These results reveal that CA stress has a negative impact on physiological homeostasis in the shrimp gills by inducing oxidation and ER stress and by interfering with immunity, apoptosis, detoxification, and osmotic adjustment. [ABSTRACT FROM AUTHOR]

Riverine export of carbon (C) is an important part of the global C cycle; however, most riverine C budgets focus on individual forms of C and fail to comprehensively measure both organic and inorganic C species in concert. To address this knowledge gap, we conducted high frequency sampling of multiple C forms, including dissolved organic C (DOC), inorganic carbon (as alkalinity), particulate organic C (POC), coarse particulate organic C (CPOC), and invertebrate biomass C across the main run-off season in a predominantly rain-fed watershed in Southeast Alaska. Streamwater concentrations were used to model daily watershed C export from May through October. Concentration and modeled yield data indicated that DOC was the primary form of riverine C export (8708 kg C/km2), except during low flow periods when alkalinity (3125 kg C/km2) was the dominant form of C export. Relative to DOC and alkalinity, export of particulate organic C (POC: 992 kg C/km2; CPOC: 313 kg C/km2) and invertebrates (40 kg C/km2) was small, but these forms of organic matter could disproportionately impact downstream food webs because of their higher quality, assessed via C to nitrogen ratios. These seasonal and flow driven changes to C form and export likely provide subsidies to downstream and nearshore ecosystems such that predicted shifts in regional hydroclimate could substantially impact C transfer and incorporation into aquatic food webs. [ABSTRACT FROM AUTHOR]

In this study, the impact of salinity and alkalinity on the volumetric deformation of the Opalinus Clay from the lower sandy facies (LSF ) of Mont Terri site was investigated. Series of samples were exposed in parallel to alkaline solutions at four different pHs ( 8.8 , 11.5 , 12.5 and 13.5 ) or to saline solutions at three different osmotic suctions (π = 10 , 15 and 34 MPa ). As a reference, samples were also exposed to synthetic water at pH 7.5 and π = 1 MPa . It was found that the protocol followed above ("parallel testing") was not suitable for the LSF Opalinus Clay due to the high mineralogy variability. Therefore, a new protocol ("gradual testing") consisting of gradually exposing the same sample to different saline or alkaline solutions was adopted. It was found that the volumetric swelling strain increased with alkalinity and decreased with salinity. In the first case, the acid-base attack resulted in a dispersed structure with higher repulsive forces. Also, the precipitation of new compounds composed of the products of the dissolution of clay minerals and the species present in the alkaline solution contributed to the observed increase in swelling strain. For the saline solutions, the decrease of the thickness of diffuse double layer and the osmotically induced consolidation explained the observed decrease of swelling strain. Highlights: Salinity decreases the volumetric swelling strain of Opalinus Clay. Alkalinity increases the volumetric swelling strain of Opalinus Clay. The "parallel testing" protocol is not suitable for the Opalinus Clay. A new protocol ("gradual testing" protocol) is developed. [ABSTRACT FROM AUTHOR]

Zeolites are widely used in fields such as separation and catalysis due to their unique pore structure. However, the complexity of its crystallization process and growth mechanism presents challenges for the research and exploitation of novel zeolites. In order to achieve the development of new zeolites with specific structures and properties, this study delves into the key factors in zeolite synthesis and dealumination processes, as well as their impact on zeolite synthesis, from the perspective of changes in silicon and aluminum. It was found that selecting silicon and aluminum sources with high activity and high specific surface area could achieve the best dissolution effect, and the suitable alkalinity could help to enhance the solubility and reactivity of silicon and aluminum sources, which in turn could improve the crystallinity and yield of zeolite. Prolonging the crystallization time and increasing the crystallization temperature can accelerate the nucleation and growth of aluminosilicate gel and reduce the anticrystallization phenomenon. In addition, precise control of the pore structure of zeolite can be achieved by controlling the selection of template agents and the conditions of dealumination treatment, thereby improving the application performance of zeolite. In this study, we reveal the deep connection between influence factors, zeolite synthesis, and silicon-aluminum variations, which provides new perspectives and methods for the exploitation and application of novel zeolites. Meanwhile, through a deep understanding of the mechanism of influence factors on zeolite synthesis, it is able to target and regulate the synthesis conditions to achieve the desired zeolite structure and properties, which not only improves the efficiency and cost effectiveness of the synthesis, but also establishes a solid foundation for the further development and wide application of zeolites. Highlights: Clarified the migration and conversion of silica-aluminum in zeolite synthesis Summarized the dealumination of zeolite by different post-treatment methods Coupled synthesis and post-treatment to construct high-silica zeolite with hierarchical pore [ABSTRACT FROM AUTHOR]

Acidogenic fermentation (AF) of wastes provides a biological route to volatile fatty acids (VFA) production as an alternative to fossil hydrocarbons. As VFA are acidic in nature, the pH in AF typically drops, affecting the fermentation performance. The effect of different alkaline substances such as urea, NaOH, or CaCO3 on AF of organic residual solids (ORS), a food waste-rich fraction of municipal solid waste (MSW), was studied. Enzymes were used as an additive in simultaneous hydrolysis and fermentation (SHF) experiments. Use of urea (66 mg Urea g−1 TS) in SHF resulted in a VFA yield of 0.14 g VFA g−1 VS after 6 days, 177% higher than the control (no urea addition). pH and ammonia concentrations significantly influenced the bacterial population distribution. In SHF using NaOH/CaCO3, added alkalinity of 11 g CaCO3 L−1 did not influence VFA yields or pH control with NaOH addition at pH 7 or higher. This study demonstrates that, while increasing pH up to 8.5 using different alkaline substances improves VFA production, higher pH is detrimental to SHF due to enzyme inhibition. Finally, the use of urea as an alkaline source must be considered carefully as the acidic pH naturally reached by AF can inhibit urea hydrolysis. [ABSTRACT FROM AUTHOR]

Introduction: Environmental stresses, such as soil salinity or alkalinity, usually affect crop growth and secondary plant metabolism, with follow on effects on foliar-feeding insects. Nevertheless, the underlying mechanism of how salinealkali stress affects the key cotton pest Aphis gossypii Glover is poorly understood. Methods: In this study, we first considered effects of three types of saline-alkali stress (i.e., salinity alone, alkalinity alone - both at different concentration - and their mixed effects) on cotton plants. We then measured impacts of stress on (1) above and below plant growth traits (e.g., plant height, leaf area, root volume), (2) levels of nutrients and secondary metabolites in cotton leaves, and (3) feeding behavior, life-table parameters, and population growth of A. gossypii. We then used a path analysis to evaluate cascading effects of changes in plant growth (due to stress) and changes in levels of nutrients or secondary metabolites on growth of individual cotton aphids and aphid populations. Results: We found either salinity or alkalinity stresses significantly reduced cotton growth, increased the content of tannin, soluble sugars, and proline in the leaves, and suppressed aphid growth and development, (including longevity, fecundity, and intrinsic rate of increase) and aphid population growth. Alkalinity had stronger effects on these traits than did salinity. Discussion: This work provides insights into the bottom-up interaction mechanism by which these environmental stresses mediate aphid infestation levels in the cotton agricultural ecosystem. [ABSTRACT FROM AUTHOR]

To ensure the safe and efficient application of ocean alkalinity enhancement (OAE), it is crucial to investigate its impacts on the carbonate system. While modeling studies reported a sequestration potential of 3–30 Gt carbon dioxide (CO2) per year (Oschlies et al., 2023), there has been a lack of empirical data to support the applicability of this technology in natural environments. Recent studies have described the effect of runaway carbonate precipitation in the context of OAE, showing that calcium carbonate (CaCO3) formation was triggered if certain Ωaragonite saturation thresholds were exceeded. This effect could potentially lead to a net loss of the initially added alkalinity, counteracting the whole concept of OAE. The related precipitation can adversely affect the carbon storage capacity and may in some cases result in CO2 emissions. Experiments at the Espeland marine biological station (Bergen, Norway) were conducted to systematically study the chemical consequences of OAE deployment. The experiments lasted for 20–25 d to monitor the temporal development of carbonate chemistry parameters after alkalinity addition and the subsequent triggered carbonate precipitation process. Identified uniform patterns before and during the triggered runaway process can be described by empirical functional relationships. For approaches equilibrated to the CO2 concentration of the atmosphere, total alkalinity (TA) levels of up to 6500 µmolkg-1 remained stable without loss of total alkalinity (TA) for up to 20 d. Higher implemented TA levels, up to 11 200 µmolkg-1 , triggered runaway carbonate formation. Once triggered, the loss of alkalinity continued until the Ωaragonite values leveled out at 5.8–6.0, still resulting in a net gain of 3600–4850 µmolkg-1 in TA. The non- CO2 -equilibrated approaches, however, only remained stable for TA additions of up to 1000 µmolkg-1. The systematic behavior of treatments exceeding this level allows us to predict the duration of transient stability and the quantity of TA loss after this period. Once triggered, the TA loss continued in the non- CO2 -equilibrated approaches until Ωaragonite values of 2.5–5.0 were reached, in this case resulting in a net loss of TA. To prevent a net loss of TA, treated water must be diluted below the time-dependent critical levels of TA and Ωaragonite within the identified transient stability duration. Identified stability and loss patterns of added TA depend on local environmental conditions impacting the carbonate system, such as salinity, temperature, biological activity, and particle abundance. Incorporating such stability and loss patterns into ocean biogeochemical models, which are capable of resolving dilution processes of treated and untreated water parcels, would, from a geochemical perspective, facilitate the prediction of safe local application levels of OAE. This approach would also allow an accurate determination of the fate of added alkalinity and a more realistic carbon storage potential estimation compared to the assessments that neglect carbonate system responses to OAE. [ABSTRACT FROM AUTHOR]

The article focuses on evaluating the water quality in and around the tea gardens of Lakhimpur District, Assam, India with respect to key water indices like the Langelier Saturation Index (LSI), Ryznar Stability Index (RSI), and Practical Scale Index (PSI). It aims to assess the impact of these indices on water quality and public health, providing practical recommendations for managing corrosion and scale formation.

To enhance our understanding of the carbon cycle in the Arctic Ocean, comprehensive observational data are crucial, including measurements from the underlying ice water. This study proposed a practical method for calibrating pCO2 sensor using measured dissolved inorganic carbon and total alkalinity. Our findings suggested the minimum number of bottle samples needed for calibration to ensure 1% accuracy. Additionally, we identified the significant role of a decrease in dissolved inorganic carbon due to photosynthesis and the increase in buffer capacity of the seawater from the release of excess alkalinity by sea ice in regulating pCO2. The mean air–sea CO2 fluxes were −48.9 ± 44.6, −7.3 ± 14.6, and −1.4 ± 2.8 mmol m−2 d−1 in the southern Chukchi Sea, northern Chukchi Sea, and northern East Siberian Sea, respectively. We found a robust negative correlation between the flux and sea ice concentration in the Arctic Sea ice regions. [ABSTRACT FROM AUTHOR]

Context: Otitis externa is the infection of epithelial lining of the external auditory canal (EAC). Cerumen has an acidic potential of hydrogen (pH) which accounts for its bactericidal and fungicidal property. The acidity of the EAC decreases due to high humidity, bathing, swimming, and frequent ear cleansing, which can lead to otitis externa. Aims: To study and compare the pH of EAC in patients with otitis externa and healthy individuals. Settings and Design: Tertiary care center and prospective, observational, and comparative study. Methods: This study includes 60 subjects with 30 diagnosed with otitis externa in diseased group and 30 in nondiseased group. pH of the EAC was evaluated by placing pH strips in outer one-third of EAC for 1 min. Statistical Analysis Used: Independent sample t -test was calculated using the Statistical Package for the Social Sciences version 24.0, IBM Corporation, USA for MS Windows. Results: Of the 60 subjects, 24 out of 30 subjects in diseased group had pH more than 5.6 and no subjects had pH more than 5.6 in nondiseased group. The average pH in diseased group was 8.73 ± 1.57 and nondiseased group was 5.13 ± 0.43. Conclusion: A change toward alkalinity of EAC is an important factor for the pathogenesis of otitis externa. Treatment of otitis externa should include acidification of the EAC with treatment with antibiotics and antifungals. [ABSTRACT FROM AUTHOR]