Mixed Water Research Articles

Proposal for formulation of blocks to guarantee the sustainability of buildings in the Abidjan real estate park

A recurring fall of buildings in recent years (2013-2023) in the city of Abidjan has caused enormous material and human damage. This study was initiated in order to propose a formulation for the development of concrete blocks to guarantee the sustainability of buildings in the Abidjan real estate. The raw materials used are aggregates composed of sand, granite powder and a hydraulic binder (portland cement) then water for mixing. The aggregates were characterized before being used for the manufacture of the various FSB, FPS and FPG concrete blocks. The materials were subjected to physical and mechanical tests. The results showed that the sand and granite powder aggregates have a granular class of 0/1 and 0/2 respectively. Concerning concrete blocks, the density increases with the maturation time, namely 28 days maximum and when they are composed of both sand and granite powder (FPS). This significantly reduces the number of pores in the material. The compressive strength test showed that at 28 days of maturation, the FPS are more resistant than the FPG and FSB with respective values of 6.50 MPa; 5.31 MPa and 3.10 MPa. It appears that the addition of granite powder to the composition of the concrete blocks improves the density, porosity and compressive strength of the latter. The promotion of this formulation among concrete block manufacturers would make it possible to improve real estate construction, guarantee the durability of buildings in the Abidjan real estate park and thus avoid the possible fall of buildings.

Aquifer Leakage Recharge Controls on CBM Production: A Case Study in the Sanjiao Block, Eastern Ordos Basin, China.

Aquifer leakage recharge poses a prevalent challenge in coalbed methane (CBM) development, severely impeding its efficient production. This study focuses on the Sanjiao Block, located on the eastern margin of the Ordos Basin, and provides a comprehensive evaluation of the impact of aquifer leakage recharge on CBM well productivity, employing hydrochemical characteristics and numerical simulation. Fisher's discriminant analysis reveals a close association between external water sources for CBM wells in the Taiyuan Formation and the hydrodynamic environment: in the western stagnant zone, hydrochemical characteristics resemble those from the Shanxi Formation; in the eastern strong runoff zone, water from the Taiyuan Formation directly contributes to CBM well development; in the central weak runoff zone, hydrochemical characteristics suggest mixed water sources from the Shanxi Formation and Taiyuan Formation. The numerical simulation employs orthogonal experiments to quantify the sensitivity of aquifer geological parameters to CBM production, ranked from strong to weak for aquifer types, leakage channel properties, and aquifer physical properties. The fundamental reason for disparities in the efficacy of leakage recharge lies in categorizing aquifers into finite and infinite recharges based on their water supply capacity. The properties of leakage channels, including the location and scale, manifest as effects on the magnitude and shape of gas production characteristics in infinite and finite recharge aquifers, respectively. Furthermore, a discriminant flowchart of CBM production is presented, delineating the production characteristics of CBM wells under the influence of aquifer leakage recharge into six patterns and illustrating their distribution in the study area. This discriminant process provides scientific guidance for analyzing CBM production characteristics and evaluating potential under the influence of aquifer leakage recharge.

PSX-27 Growth performance and immune response dynamics in weaned lambs with subclinical Haemonchus contortus parasite infection

Abstract Parasite infections, particularly from Haemonchus contortus, hinder sheep production in Canada by reducing weight gain and immunity. Current diagnosis and treatment methods rely on observing symptoms and the blind administration of anthelmintic drugs, resulting in escalating costs and the development of drug-resistant parasites. This study aimed to identify the exact time-point when subclinical H. contortus parasite infection affects growth performance and triggers an immune response. A total of 60 Rideau Arcott ewe lambs (~7-8 mo old), confirmed to be parasite-free, were randomly assigned in a 2 x 2 factorial design assessing inoculation treatment (TRT): oral inoculation (IN) with a solution containing 5,000 L3 strain of H. contortus or sham inoculation (CT) using water solution as control; and drench (DRENCH) administration: oral drench (D), 28-days post-inoculation, with a combination of 0.08% ivermectin solution (200 mcg per kg of BW; Durvet®) and 10% oral suspension of fenbendazole (2.5 mL per 50 kg of BW; Safe-guard®), or water solution (non-drenched, ND), resulting in four treatment groups: IN-D, IN-ND, CT-D, and CT-ND (n=15/treatment). Lambs were equally assigned to four feedlot pens (two replicates/treatment) for 57 days (d) with ad libitum access to a grain-based total mixed ration and water. Animals were individually weighed (BW) and blood sampled on days -1 and 0 (baseline), as well as on days 7, 21, 28, 35, 42, 56, and 57 post-inoculations (DAY); average daily gain (ADG) was calculated for the entire experimental period. White blood cells count (WBC) was used as an indicator of infection and red blood cell count (RBC) as indicator of anemia. Data was analyzed using a mixed-effects model including TRT, DRENCH, DAY (and their interactions) as fixed effects. Overall, CT lambs were heavier (TRT effect; P < 0.05) and had a tendency of greater (TRT effect; P = 0.08) ADG than IN lambs. The IN lambs had a tendency of greater (TRT*DAY; P = 0.07) WBC on d 7 than CT lambs. Additionally, IN-ND had lower (TRT*DRENCH; P < 0.05) WBC than IN-D lambs (1.9 and 2.0 ± 0.042 x 109/L, respectively). A significant (TRT*DRENCH*DAY; P < 0.01) interaction was found on RBC. The CT-D had lower (P < 0.05) RBC on d 7 and greater (P < 0.05) on d 28, 35, 42, and 57 than IN-ND as well as on d 28 than IN-D. Furthermore, CT-ND had greater (P < 0.05) RBC on d 21, 28 and 35 than IN-D and from d 21 to 57 than IN-ND. The IN-D had greater (P < 0.01) RBC from d 35 to 57 than IN-ND. These findings suggest compromised growth in both drenched and non-drenched infected groups. Infection slightly peaked in the infected lambs on d 7 post-inoculation, but drench administration was effective at mitigating overall infection by day 21 and the anemia by day 35.

The use of graphene nanoplatelets for enhancement of the compressive strength of mortar containing high-levels of natural Pozzolan

High Pozzolan concrete has an extended setting time and inhibits early-age compressive strength development, which can cause construction delays and limit its application in the concrete industry. The main aim of this study is to evaluate the effectiveness of graphene nanoplatelets (GNPs) in enhancing the mechanical properties of mortar containing high levels of natural Pozzolan. In the beginning, a relatively simple ultrasonication treatment process produced an almost uniform dispersion of GNPs in the mixing water to avoid agglomeration which limits the efficiency of GNPs. Tests on engineering properties indicated that the compressive strength of mortar containing 40 and 60 % natural Pozzolan as a partial replacement of cement was enhanced with the addition of the optimum content of graphene nanoplatelets which was found to be 0.03 % and 0.01 % by weight of binder at 40 % and 60 % cement replacement levels, respectively. The compressive strength was enhanced by 29.6 %, 27.4 %, and 27.5 % at 40 % cement replacement level, and by 86.3 %, 23.7 %, and 25.8 % at 60 % cement replacement level at 7, 28, and 56 days of curing, respectively. SEM investigations indicated that the addition of GNPs densified the structure thus enhancing the performance of mortar.

Effect of CO2 Nanobubble Water on the Fracture Properties of Cemented Backfill Materials under Different Aggregate Fractal Dimensions

In order to cope with climate change and achieve the goal of carbon neutrality, the use of carbonization technology to enhance the performance of cement-based materials and achieve the purpose of carbon sequestration has become a very promising research direction. This paper considers the use of CO2NBW as mixing water for cement-based materials, aiming to improve the carbonization efficiency of materials to achieve the goal of carbon neutrality. This time, the effect of CO2NBW on cementitious filling materials under different aggregate fractal dimensions was studied through uniaxial compression tests and acoustic emission technology. The effect of CO2NBW on the mechanical properties and crack evolution of the material was discussed. The results showed that CO2 nanobubbles significantly improved the strength of cemented filling materials under different fractal dimensions, and the uniaxial compressive strength was most significantly improved by 23.04% when the fractal dimension was 2.7824. In addition, the characteristics of acoustic emission ring counts and energy parameters indicate that CO2 nanobubbles help improve the overall pore structure of the sample, affecting the macroscopic strength. However, the addition of CO2 nanobubbles reduces the limit energy storage ratio of elastic strain energy, which indicates that excessive CO2 concentration may affect the hydration reaction of the cementing material.

Multidisciplinary hydrogeochemical and isotopic assessment of the Pordenone Plain (Northeastern Italy) for water resources sustainability

This study aims to comprehensively characterize the hydro-geochemical and isotopic features of the complex groundwater system in the Pordenone Plain (northeastern Italy). The area is an important industrial and agricultural area exposed to severe anthropogenic pressure and climate change, which put its water resources at risk in terms of quantity and quality, making it of high scientific and social interest. The hydrogeological setting of the Pordenone Plain has been previously simplified as a phreatic continuous aquifer in the High Plain that changes into a multilayered aquifer system towards the Low Plain. However, this study reveals significant lithological and structural heterogeneities in the High Plain that exert a strong influence on its subsurface hydrodynamics. All waters exhibit a Ca(Mg)–HCO3 composition with relatively high Na–K values in the aquifers of the Low Plain likely related to cation exchange processes. Water stable isotopes (δ2H–H2O and δ18O–H2O) indicate that the deep aquifers in the Low Plain are confined by impermeable geological formations, such as clays and siltstones, which entirely restrict water mixing with shallower aquifers. Concurrently, tritium analysis provides evidence of slow recharge and flow rate. Three primary groundwater flows have been identified within the plain, as follows: 1) a surface flow that affects the unconfined or semi-confined aquifers of the High Plain hosted in gravelly sediments; 2) an intermediate flow fed by the pedemontane zone, which includes unconfined deep aquifers of the High Plain, semi-confined/shallow aquifers (at a depth of 40–50 m) located near the resurgence belt area and karst springs located in eastern pedemontane of the Cansiglio Plateau; 3) a deep flow fed by the mountainous zone that affects the deep confined aquifers of the Low Plain. A reliable hydrogeochemical conceptual model has been developed to explain the compositional variability of the studied waters, providing valuable insights for the sustainable management of groundwater resources in the Pordenone Plain.

Method for introducing carbon nanotubes into fine-grained concrete

This work discusses the use of a modifying complex additive to concrete with the inclusion of carbon nanotubes “Taunit-M” and the SP-3 plasticizer. Two methods of introducing nano-sized additives into the composition of fine-grained concrete, as well as their combination, are considered. The results of a series of tests of beam samples aged 28 days are presented using two methods of introducing nanotubes, namely: the use of an ultrasonic dispersant and the use of a linear induction rotator (LIR). The positive effect of introducing nanotubes on the strength characteristics of concrete has been established. It has been determined that the use of LIR technology provides an increase in strength due to a double effect: activation of the cement binder and distribution of the nanoadditive using active mixing due to vortex action. Ultrasonic dispersion, in turn, ensures the effective introduction of the plasticizer into the mixing water.

Episodic fluid charging and mixing triggers calcite-bearing agates in the Permian Emeishan Basalt, SW China

ABSTRACT Agate, a distinctive form of banded chalcedony, derives its characteristic appearance from the deposition of silica and the presence of impurities. A significant variety of agate-bearing calcite was identified in the Permian Emeishan Basalt located in the southwestern Sichuan Basin. This calcite-bearing agate provides valuable insights into the complex interplay and evolution of fluids and minerals. This study aims to provide a detailed description and analysis of the microscopic textural and geochemical characteristics of the agate, while elucidating the sequence of mineral deposition, fluid properties, and the genetic mechanism underlying its formation. The findings reveal that the agate primarily consists of lamellar calcite and banded chalcedony, exhibiting a variety of textures, thicknesses, and colours. Through the analysis of the transformation and precipitation of epidote and allanite, and the identification of four types of calcites and five micro-silica textures, it has been confirmed that the early stage of fluid in geodes involved the mixing of meteoric water with post-magmatic hydrothermal fluid. The middle and late stages involve the mixing of magmatic-hydrothermal fluid with organic-acid fluid. The charging of silica-rich hydrothermal fluids and the generation of hydrocarbons from organic matter cause fluctuations in SiO2 concentration, pH, and crystallization rates, contributing to the diversity of silica minerals, such as chalcedony and quartz. The interlayered growth observed between chalcedony and calcite is attributed to secondary metasomatism, which occurs after the dehydration and transformation of chalcedony due to increasing temperatures. Notably, the internal texture of the agate is somewhat influenced by pressure variations caused by the episodic charging of the fluid.

Comprehensive approach integrating water quality index and toxic element analysis for environmental and health risk assessment enhanced by simulation techniques

Due to water shortages and the potential impact of Ethiopia’s new dam on the Nile River, Egypt is seeking new water resources. This study assesses the drinking water quality and associated risks from potentially toxic elements (PTEs) in the Quaternary aquifer (QA) in Beni-Suef, Egypt. Using a comprehensive approach, including PHREEQC geochemical modeling, ionic ratios, multivariate statistical analyses, and the integrated weight water quality index (WQI), the study evaluated the sources of ion contamination and the mixing of Nile water with QA. Various indices, such as the Heavy Metal Pollution Index (HPI), ecological Risk Index (RI), Hazard Quotient (HQ), and Hazard Index (HI), were used to assess ecological and health risks. Monte Carlo simulations provided probabilistic assessments of non-carcinogenic risks for adults and children. GIS tools were used to map risk indices, identifying the most deteriorated locations for sustainable management. The hydrochemical analysis revealed water facies including Na–Cl, Ca–Mg–HCO3, and mixed types, influenced by carbonate dissolution, ion exchange, and silicate weathering. Contamination sources, particularly in the north and south, were linked to agricultural activities, irrigation return flow, municipal waste, and evaporation. The WQI indicated that 10.14% of samples were extremely poor, 21.7% were poor, 26% were medium, and 42% were good to excellent. PTE contamination varied, with HPI values indicating good water quality in the central area in 53.6% of the collected samples (HPI < 30), but contamination in the north and south is high (HPI > 51). Ecological Risk Index values were below the threshold in 100% of samples (RI < 30), confirming water safety regarding PTEs. In comparison, for hazard index (HI) through oral/ingestion, adults exhibited HI values ranging from 0.012 to 2.16, while children showed higher values, ranging from 0.045 to 8.25. However, the hazard index for oral/ingestion exceeded safe limits in the north and south (HI oral > 1), posing non-carcinogenic risks. Monte Carlo simulations revealed significant risks from oral exposure to manganese (HQ oral > 1), particularly in El-Wasta and El-Fashn, necessitating further treatment and management.

Feasibility Research on Surface Water Reinjection into the Sandstone Geothermal Reservoir of the Guantao Formation in Tianjin Based on Laboratory Experiments

Tianjin possesses abundant geothermal resources, and geothermal reinjection is an effective strategy for maintaining the sustainable development and utilization of these resources. However, several issues have arisen in the reinjection of sandstone geothermal reservoirs in the Tianjin area, including a mismatch between the reinjection capacity and effluent capacity, as well as challenges related to continuous reinjection. Therefore, it is crucial to investigate the reinjection of exogenous water into sandstone pore-type geothermal reservoirs. This study focuses on the geothermal reservoir of the Guantao Formation in the Binhai New Area. The surface water treatment process for reinjection into sandstone geothermal reservoirs was determined through water treatment simulation experiments. Additionally, experiments examining the interaction between the reinjected water and reservoir rock were conducted to assess the feasibility of using treated surface water for reinjection into sandstone geothermal reservoirs. The hydrogeochemical response mechanisms and the impact on the reservoir under reinjection conditions were also investigated. The results indicate that a nanofiltration module and tubular microfiltration membrane are essential to ensure the stability of the system. The pH and TDS of water samples decreased after reinjecting mixed water (HHS) into the sandstone reservoir. The hydrochemical type consistently remained Cl-Na. The conventional water chemistry components and trace elements were influenced by the corresponding water–rock reactions. The reservoir minerals exhibited minimal precipitation, primarily consisting of K-feldspar and Fe-dolomite. The minerals produced during the experiment accounted for only 0.08% of the total cuttings’ mass, indicating a negligible impact on the reservoir structure. PHREEQC was employed to simulate the changes in mineral saturation index before and after the reinjection of mixed water and geothermal water, respectively. Notably, similar hydrogeochemical changes were observed in the geothermal fluids. Thus, this study demonstrates the feasibility of reinjecting treated surface water into sandstone geothermal reservoirs from a hydrogeochemical perspective. This research provides valuable insights for the development of external water reinjection projects in hot spring health care units, contributing effectively to the achievement of carbon peaking and carbon neutrality goals.

Highly Anion‐Conductive Viologen‐Based Two‐Dimensional Polymer Membranes as Nanopower Generators

AbstractTwo‐dimensional polymers (2DPs) and their layer‐stacked 2D covalent organic frameworks (2D COFs) membranes hold great potential for harvesting sustainable osmotic energy. The nascent research has yet to simultaneously achieve high ionic flux and selectivity, primarily due to inefficient ion transport dynamics. This is directly related to ultrasmall pore size (&lt;3 nm), much smaller than the duple Debye length in the diluted electrolyte (6–20 nm), as well as low charge density (&lt;4.5 mC m−2). Here, we introduce a π‐conjugated viologen‐based 2DP (V2DP) membrane possessing a large pore size of 4.5 nm, strategically enhancing the overlapping of the electric double layer, coupled with an exceptional positive surface charge density (~6 mC m−2). These characteristics enable the membrane to facilitate high anion flux while maintaining ideal selectivity. Notably, V2DP membranes realize an impressive current density of 5.5×103 A m−2, surpassing benchmarks set by previously reported nanofluidic membranes. In the practical application scenario involving the mixing of artificial seawater and river water, the V2DP membranes exhibit a considerable ion transference number of 0.70 towards Cl−, contributing to an outstanding power density of ~55 W m−2. Theoretical calculations reveal the important role of the large quantity of anion transport sites, which act as binding sites evenly located in the positively charged N‐containing pyridine rings. These binding sites enable kinematic coupling and decoupling between anions and the V2DP skeleton, establishing a continuous Cl− ion transport pathway. This work demonstrates the great promise of large‐area ultrathin 2DP membranes featuring highly organized charged ion transport networks when applied for osmotic energy conversion.

A Mathematical Model of Diel Activity and Long Time Survival in Phototrophic Mixed-Species Subaerial Biofilms

Subaerial biofilms (SAB) are intricate microbial communities living on terrestrial surfaces, of interest in a variety of contexts including cultural heritage preservation, microbial ecology, biogeochemical cycling, and biotechnology. Here we propose a mathematical model aimed at better understanding the interplay between cyanobacteria and heterotrophic bacteria, common microbial SAB constituents, and their mutual dependence on local environmental conditions. SABs are modeled as thin mixed biofilm-liquid water layers sitting on stone. A system of ordinary differential equations regulates the dynamics of key SAB components: cyanobacteria, heterotrophs, polysaccharides and decayed biomass, as well as cellular levels of organic carbon, nitrogen and energy. These components are interconnected through a network of energetically dominant metabolic pathways, modeled with limitation terms reflecting the impact of biotic and abiotic factors. Daily cylces of temperature, humidity, and light intensity are considered as input model variables that regulate microbial activity by influencing water availability and metabolic kinetics. Relevant physico-chemical processes, including pH regulation, further contribute to a description of the SAB ecology. Numerical simulations explore the dynamics of SABs in a real-world context, revealing distinct daily activity periods shaped by water activity and light availability, as well as longer time scale survivability conditions. Results also suggest that heterotrophs could play a substantial role in decomposing non-volatile carbon compounds and regulating pH, thus influencing the overall composition and stability of the biofilm.

Climate Change Adaptation Information Usability Among Maize Farmers in Ido Local Government Area of Oyo State, Nigeria

The availability of climate change information has not always led to more successful adaptation; even when climate change adaptation information is available, there are still obstacles to its efficient use. Furthermore, the tactics required to communicate climate information to end-users for successful adaptation have received less attention. This study focuses on utilization of available climate change adaptation information among maize farmers in the study area. Simple random sampling technique was used to select 203 respondents for data collection. The data were collected using a questionnaire and analysed through the use of the standard statistical package for social sciences. The communication strategies used include inter-personal, audio, visual and social media. The results revealed that the strategies used in communicating climate change adaptation information to maize farmers in the study area yielded great influence in terms of benefits to the farmers such as the increase in income, prevention of yield loss, reduced soil degradation, maintaining good human health status, and improved weed management. The information that is popularly utilised is mixed cropping (61.6%), water management (58.1%), and early warning (58.1%). A significant relationship existed between communication channels (r=0.8, p&amp;lt;.05) and respondents’ climate change adaptation information utilization. Poor understanding of the message and lack of funds to put the information into practice hinders some respondents from utilising adaptation information. Hence, extension agents need to locate these category farmers and link them with service providers that could provide incentives or credit facilities for sustainable utilisation of available information to combat climate change.

Fabrication and analysis of a novel and sustainable set-up for safe and economic hydrotherapy

Hot water immersion therapy has been found a promising therapy that offers several potential benefits to the human body, including pain relief, wound healing, improved blood circulation, stress relief, and improved sleep. However, the therapy is not widely used by the general population, especially the middle-class and lower-middle-class populations. The reasons for this could be the accessibility and cost of the therapy. This article introduces an innovative hot water immersion therapy set-up designed to increase the therapy's accessibility to a broader audience. The proposed set-up is engineered for easy home fabrication and installation without requiring special tools or skills, ensuring user safety through the use of electrically leak-proof components. A significant benefit of this set-up is its integration with a standard household geyser for water heating, which obviates the need for a dedicated geyser typically associated with commercial hot water immersion therapy systems, thereby reducing the overall initial, operational, and maintenance costs. The set-up has been successfully fabricated, installed, and tested, proving its effectiveness and efficiency. Among the four modes experimentally analyzed, Mode 4, a mix of regular and hot water with a combined flow rate of 8.06 L/min, leads to minimum waiting and geyser on-time of 19.85 min. In addition to the direct benefit of reduced liquid petroleum gas consumption, choosing Mode 4 contributes to an overall lower environmental footprint. This study aims to raise awareness of hydrotherapy and make it accessible to the general public.

Improved Low-field NMR porosity characterization of cementitious materials containing water-soluble organic admixtures

Water-soluble organic admixtures (WSOAs) are widely used in cementitious materials, and may affect the porosity, but their effects on low-field nuclear magnetic resonance (LF-NMR) measurement are often overlooked. Using viscosity modifying admixture (VMA) as an example, this study demonstrates the presence of WSOAs would lead to an overestimation of porosity and a leftward shift of pore size distribution using LF-NMR. This is attributed to the formation of hydrogen bonds between polymer and water molecules, and the decreased distance between nuclear spins, respectively. A strategy is proposed to improve the accuracy of the porosity characterization by eliminating the additional effects of WSOAs in LF-NMR testing. The results show that the addition of small molecular mass non-ionic VMAs replacing mixing water (within a 20 % replacing rate) does not alter the porosity of the paste. This method can be extended to characterize the porosity of various porous materials containing WSOAs.

Machine Learning-Guided Cycle Life Prediction for Electrochromic Devices Based on Deuterium and Water Mixing Solvent.

Electrochromic devices have demonstrated considerable potential in a range of applications, including smart windows and automotive rearview mirrors. However, traditional cycle life testing methods are time-consuming and require significant resources to process a substantial amount of generated data, which presents a significant challenge and remains an urgent issue to be addressed. To address this challenge, we proposed the use of Long Short-Term Memory (LSTM) networks to construct a prediction model of the cycle life of electrochromic devices and introduced an interpretable analysis method to further analyze the model's predictive capabilities. The original dataset used for modeling was derived from preliminary experiments conducted under 1000 cycles of six devices prepared with varying mixing ratios of heavy water (D2O). Furthermore, validation experiments confirmed the feasibility of the D2O mixing strategy, with 83% of the devices exhibiting a high initial transmittance modulation amplitude (ΔT = 43.95%), a rapid response time (tc = 7 s and tb = 8 s), and excellent cyclic stability (ΔT = 44.92% after 1000 cycles). This study is the first to use machine learning techniques to predict the cycle life of electrochromic devices while proposing performance enhancement and experimental time savings for inorganic all-liquid electrochromic devices.

Surface carbonate dynamics in a temperate coastal system in the Northern Yellow Sea, China

The carbon sink/source in estuaries and coastal seas may have significant implications for regional climate change. This study investigated seawater carbon dioxide partial pressure (pCO2), aragonite saturation state (Ωarag), and related carbonate parameters in the Yalu River estuary and the adjacent Northern Yellow Sea, China, in September 2023. The results indicate that seawater pCO2 ranged from 261 to 1121 μatm, while Ωarag ranged from 0.49 to 3.34 in the study area. High pCO2 were observed in the estuarine and northwestern areas, whereas low pCO2 were found in the southern offshore area. In the estuarine area, high pCO2 levels were attributed to the input of diluted water from the Yalu River. In the southern areas, low pCO2 were a result of primary production, while community respiration played an important role in increasing seawater pCO2 in the northwestern area. On the other hand, seawater Ωarag was extremely low in the estuarine area, and greater than 1.5 in the southern offshore area. Ωarag in the study area was mainly controlled by water mixing and temperature. The study area acted as a source of atmospheric CO2 with an average air-sea CO2 flux of 6.2 mmol m−2d−1 in autumn, which was relatively high compared with other marginal seas. The high pCO2 and low Ωarag associated with diluted water inputs and community respiration could weaken the ability of coastal oceans to uptake CO2. Therefore, it is crucial to explore ways to reduce CO2 levels in riverine and adjacent coastal seas.

Modal Decomposition of Internal Tides in the Luzon Strait through Two-Dimensional Fourier Bandpass Filtering

Internal tides are pivotal dynamic processes enhancing the mixing of oceanic waters and facilitating energy transfer across various scales within the ocean. In recent years, the proliferation of satellite altimetry observations has enabled global predictions of the elevation and phase of internal tides. This study, leveraging the advanced global internal tide prediction model known as the Multivariate Inversion of Ocean Surface Topography-Internal Tide Model (MIOST-IT), employs a two-dimensional Fourier bandpass filtering approach to decompose the internal tides in the Luzon Strait, thereby addressing the east–west directional blind zones inherent in along-track satellite altimetry-based modal decomposition. To further elucidate the propagation trajectories of individual tidal modes in different directions, we introduce the directional Fourier filter method to characterize the spatial distribution features of each modal internal tide in the vicinity of the Luzon Strait. This work significantly enhances the accuracy and reliability of extracting parameters for distinct modal internal tides, furnishing a scientific basis for subsequent studies on internal tide dynamics and model refinement.

Advancing the Sustainability of Geopolymer Technology through the Development of Rice Husk Ash Based Solid Activators

Rice husk ash (RHA), an agricultural waste byproduct, has already been tested as a component in geopolymeric binders, typically as part of the precursor solid mix, alongside materials like fly ash (FA), slag, and cement. This study presents a novel approach where RHA is employed to create a solid activator, aimed at entirely replacing commercial sodium silicates. The synthesis process involves mixing RHA, NaOH (NH), and water by applying a SiO2/Na2O molar ratio equal to 1, followed by mild thermal treatment at 150 °C for 1 h, resulting in the production of a solid powder characterized by high Na2SiO3 content (60–76%). Additionally, microwave treatment (SiO2/Na2O = 1, 460 W for 5 min) increases the environmental and economical sustainability of alkali silicates production from RHA since this processing is 12 times faster than conventional thermal treatment reducing at the same time the final product’s embodied energy. The efficacy of this new material as a sole solid activator for the geopolymerization of Greek FA is investigated through various techniques (XRD, FTIR, SEM). One-part geopolymers prepared with RHA-based solid activators demonstrated mechanical performance comparable to those prepared with commercial products (~62 MPa at 7 days). This research contributes to the advancement of sustainable construction practices emphasizing the importance of local materials and reduced environmental impact in achieving long-term sustainability goals.

A comparative study of wet-mix vs. dry-mix to prepare geopolymer artificial aggregates utilizing municipal solid waste incineration bottom ash (IBA) via crushing technique

The demand for sustainable alternatives to utilize incinerator bottom ash (IBA) alongside the current scarcity of natural aggregates drives the construction industry to seek innovative solutions, among which cold bonding geopolymer artificial aggregates (GPA) have tremendous leverage. This study suggests combining dry-mix and crushing techniques for producing IBA-GPA, aiming to overcome the challenges of volume instability related to metallic aluminum. The materials used as precursors include IBA, CFA, and GGBS, with anhydrous sodium metasilicate as the activator. The mixing method, water content, and IBA content are key parameters examined in this research, using characterization techniques such as XCT, TCLP, XRD, FTIR, and SEM. The results show that a proper balance between water and IBA contents is crucial for producing high-quality IBA-GPA cubes, at which the proposed technologies successfully mitigate volume instability and enhance the reliability of IBA-GPA. The dry-mix samples were less porous and more compact, with irregularly shaped pores, while the wet-mix samples had a foam-like structure with more uniformly spherical pores. Adding IBA increased pore sizes in both samples, with a more pronounced effect in the wet-mix samples. The findings provide insights into the impact of mixing methods on the properties of IBA-GPA.