Silicate Concentrations Research Articles

Scaling and cleaning of silica scales on reverse osmosis membrane: Effective removal and degradation mechanisms utilizing gallic acid

Silica scaling on membranes represents one of the most important issues in industrial water systems because of its complex composition and difficulty in removal. However, there is a lack of understanding of the mechanisms for cleaning silica scales from reverse osmosis (RO) membranes. To address this research gap, this study investigated the scaling and cleaning behavior of silica on RO membrane processes, with a specific focus on the silica scale cleaning mechanism using gallic acid (GA). The membrane flux continuously decreased with operation time, even at the lowest initial silicic acid concentration, owing to silica scale blockage. The GA solution exhibited a strong efficacy in cleaning silica-scaling RO membranes. The membrane flux returned to 89.7% of the initial value by removing 81.87% of the silica scale within the first 30 min of the study period. The cleaning mechanism of GA involved its adsorption onto the surface of silica scale particles to form a surface complex and subsequently transition into a water-soluble 1:3 complex within the solution. This complex interaction facilitated the gradual decomposition of the silica scales that adhered to the membrane surface. This study has valuable implications for the development of efficient and effective silica scale cleaning solutions, providing insights into the complex interplay between GA and silica scaling mechanisms.

The Effects of a Fishery Complementary Photovoltaic Power Plant on the Near-Surface Meteorology and Water Quality of Coastal Aquaculture Ponds

To date, most studies focus on the ecological and environmental effects of land-based photovoltaic (PV) power plants, while there is a dearth of studies examining the impacts of water-based PV power plants. The effects of a fishery complementary PV power plant, a kind of water-based PV technology, on the near-surface meteorology and aquaculture water environment were investigated in coastal aquaculture ponds in southeast China. The results showed that PV prevented 89~93% of the solar radiation on the surface of the pond, resulting in an average reduction in water temperature of 1.5 °C and a substantial decrease in light intensity of 94%. Furthermore, it weakened the wind speed by 41~50% and elevated the surface air temperature by an average of 0.6 °C. In addition, PV power results in an impressive decrease in chlorophyll-α of 72~94% and a notable increase in dissolved oxygen (DO) concentrations of 8~24%. PV power also reduced the concentration of labile phosphate, active silicate, total nitrogen, total phosphorus, and total organic carbon. However, the PV power did not have a substantial influence on the concentrations of nitrate and ammonium. Our results highlight that fishery complementary PV power plants may be able to improve water quality and benefit shade-loving species.

Water stratification alters phytoplankton assemblages in scallop farming waters of the North Yellow Sea in China

As evaluation indicators of the primary productivity, the phytoplankton biomass and community structure are of great significance to the fishery industry, which can be driven by ocean currents, nutrients and water stratification. In the present study, the characteristics of phytoplankton assemblages in different water layers of a typical Yesso scallop farming area in Zhangzi Island, the North Yellow Sea were investigated from March 2021 to January 2022. According to the vertical distribution of temperature, water stratification was observed from June to August (stratification period), and disappeared in March, October and the following January with vertical homogeneity (mixing period). 18S rRNA gene sequencing results revealed that Pyrrophyta was the most dominant phylum during the sampling period, with high gene proportions in the stratification (63.36%) and mixing periods (77.35%). The gene proportion of Bacillariophyta in the stratification period was 5.44%, which was significantly lower than that in the mixing period of 8.93% (p < 0.05). Moreover, Pseudo-nitzschia, a toxin-producing taxon affiliated with Bacillariophyta, exhibited a significantly higher proportion in the stratification period than in the mixing period. During the stratification period, a number of toxin-producing taxa such as Pseudo-nitzschia and Karlodinium were enriched in the bottom layer, which was 1.29-fold and 1.37-fold of that in the surface layer, respectively. Redundancy analysis showed that phosphate and water temperature were major environmental factors driving the vertical distribution of phytoplankton assemblages. The phosphate (0.11 μM) and silicate (2.09 μM) concentrations in the surface layer approached the minimum threshold for phytoplankton growth, and the stoichiometric limitation of phosphate was detected in the surface and middle layers. Collectively, these results indicated that the decreased proportion ratio of Bacillariophyta to Pyrrophyta and unfavorable community composition of Bacillariophyta for scallops were observed during summer, which might result from the phosphate limitation driven by water stratification. The results will further our understanding of the dynamics of phytoplankton communities under the background of intensifying ocean stratification and provide ecological guidance for mollusc mariculture.

Evaluation of Properties of Concrete Without Cement Produced Using Fly Ash‐Based Geopolymer

AbstractThe use of ordinary Portland cement (OPC) in the construction industry is inevitable. The huge production of OPC and its use in infrastructural development pose an environmental impact. Greenhouse gas emitted increases the global temperature and it is an alarming sign to everybody on the planet. Concrete is the most consuming material which is produced by using OPC and it is proven that OPC contributes a lot to CO2 emission. Hence in this study attempt is made to produce concrete by using environment‐friendly material like fly ash along with alkaline activators, which is termed Geo polymer concrete. The by‐product fly ash is widely available worldwide. It is a by‐product of thermal power plants. The use of fly ash in concrete produces less expensive and more cost‐effective concrete than concrete made up using OPC. Due to its high silicate and alumina content, fly ash reacts with an alkaline solution to create an aluminosilicate gel that binds the aggregate and results in high‐quality concrete. Fly ash is finer than cement, it occupies the pores of cement after hydration. This would result in denser concrete which gives higher strength. In comparison to ordinary concrete, fly ash‐based geopolymer concrete offers better resistance to aggressive environments and high temperatures. In the present study, an alkaline activator of molarity 8 is used to prepare geopolymer concrete. The test specimens are cast and cured for 28 days. Test results indicate that an alkaline liquid fly‐ash ratio (0.4) produces higher mechanical properties. Hence, geopolymer concrete produced in this study is found to be cost‐effective and environment friendly.

Tuning biodegradability, bone-bonding capacity, and wear resistance of zinc-30% magnesium intermetallic alloy for use in load-bearing bone applications

This work aimed to improve the rapid biodegradation, poor wear resistance properties, and lack of bioactivity of metallic biomaterials to be used in orthopedic applications. In this context, zinc–magnesium (Zn–Mg) alloy with successive contents of calcium silicate (CaSiO3) and silicon nitride (Si3N4) was prepared using powder metallurgy technique. After sintering, their phase composition and microstructure were investigated using the X-ray diffraction technique and scanning electron microscopy (SEM), respectively. Furthermore, their degradation behavior and ability to form hydroxyapatite (HA) layer on the sample surface after immersion in simulated body fluid (SBF) were monitored using weight loss measurements, inductively coupled plasma-atomic emission spectroscopy, and SEM. Moreover, their tribo-mechanical properties were measured. The results obtained showed that the successive contents of CaSiO3 were responsible for improving the bioactivity behavior as indicated by a good formation of the HA layer on the samples’ surface. Additionally, ceramic materials were responsible for a continuous decrease in the released ions in the SBF solution as indicated by the ICP results. The tribology properties were significantly improved even after exposure to different loads. Based on the above results, the prepared nanocomposites are promising for use in orthopedic applications.

Macronutrients and their ratios in different plant species growing in solonchaks of Western Transbaikalia

The macroelement composition and ratios of macroelements in dominant and co-dominant plants growing on lakeside solonchaks of Western Transbaikalia: from salt-sandy strips on dried shoals with pioneer groupings, side slopes to plains with cheieves, irises and leymus communities were studied for the first time. General regularities characterizing their macroelement composition were established for annual halophytes of salt-sand strips of the Beloe Lake shoreline. It has been revealed that pioneer perennials are formed on the mortmass of annuals. Mortmass of different duration of formation was characterized by high silicic content and concentrations of S, Fe, and Mg with a minimal amount of K, and the K : Na ratio was 0.03–0.04. Biological productivity of lakeside saltmarsh communities was determined to be normal and elevated, 1490–3080 g dry mass/m2/year. Species differed significantly in the macroelement composition depending on the conditions of growing in the coastal zone of brackish lakes. Common for the chemical composition of plants was a relatively high content of nitrogen and ash. It was found that by the total concentration of K, Ca, Mg, Na, Si in the dry matter, annuals of the Chenopodiaceae family dominated due to the high amount of sodium. In spite of non-compliance with the norms of the ratios of most macronutrients in the dry matter of plants, especially by K : (Ca + Mg) and K : Na, all species are used as fodder in different periods of the year.

Effect of Na2S+NaOH Pre-Identification Leaching on Oxidized Refractory Au-Ag Ores

This study was conducted to investigate the effect of the alkaline sulfide (Na2S+NaOH) pre-identification process on cyanide leaching performance in oxidized refractory gold-silver ores. The ore has intensive oxide, carbonate, and silicate content, and contains Au/Ag minerals containing electum, acanthite, and silver-bearing FePbZn Sulphate-Arsenate/Hydroxide minerals together with Fe, Pb, and Zn minerals. Niğde Ulukışla refractory Au/Ag ore has 8-9 g/T gold and 170-180 g/T silver grades. In mineralogical examinations, it was found that these metals were closed in minerals such as iron oxy/oxyhydroxide, calcite, and quartz or neighboring these minerals. In the cyanide soluble process after alkali sulfide preliminary procedure at room temperature, metal extraction yields were obtained as 62% for gold and 7% for silver. It is seen that silver is adversely affected by this process compared to the direct cyanidation process. However, after the hot alkali treatment process, metal extractions improved by approximately 25% of gold and 74% of silver. This increase in yield can be considered as converting Ag-oxyhydroxide into soluble Ag forms as a result of the effect of hot alkaline sulfur leaching on the cyanide process. The most important advantage of this decomposition process is to achieve high metal extraction efficiency in lower alkali concentrations.

Effects of large dams on the aquatic food web along a coastal stream with high sediment loads

The contribution of two basal energy sources – detrital organic matter and primary producers – as part of aquatic food webs varies typically along river continua. A host of barriers to river flow increase the water residence time and sediment and nutrient retention in reservoirs worldwide, and potentially alter the balance between detritus-based and algae-based energy pathways in the downstream food webs. We explored this issue on the Sélune River (Normandy, France), a small coastal stream that drains an agricultural catchment with high sediment runoff. Seasonal measurements of the following parameters were compared upstream and downstream of the reservoirs of two large dams (16 m and 36 m high): sediment fluxes, nutrient and chlorophyll a concentrations, algal communities in the epilithic biofilm (taxonomic composition, biomass and growth), and benthic invertebrate communities (abundance and trophic guild structure). As anticipated, annual sediment fluxes were much lower downstream of the reservoirs, where significant decreases in water turbidity, phosphate and silicate concentrations were recorded. A higher chlorophyll a concentration in water and a higher contribution of pelagic algae taxa to the photosynthetic biofilm suggested drifting and deposition of reservoir-borne phytoplankton downriver. Photosynthetic biofilm growth was higher downstream of the reservoirs in spring and fall, and so was the abundance of herbivores in the invertebrate community, notably scrapers and algae eaters. Energy pathways within riverine food webs were traced using stable isotope analyses of carbon (C) and nitrogen in the tissues of aquatic consumers (invertebrates and fish). Mixing models revealed a discontinuity in the origin of the C entering the food webs along the river continuum, confirming a greater contribution of algal C to aquatic consumers downstream of the reservoirs. These results illustrate mechanisms whereby large reservoirs can modulate C flow in food webs along a small coastal river with high sediment loads, and make it possible to anticipate the effects of dam removal on the future river ecosystem.

The Influence of Differences in Silicate Concentration on the Growth of Microalgae Thalassiosira sp. at the Laboratory Scale

Thalassiosira sp. is a planktonic microalga from the class Bacillariophyceae (diatom) used as natural feed in the cultivation of fish, shrimp, and mollusks. Some diatom species, including Thalassiosira sp., require silicate for the formation of their cell walls. This research aims to investigate the influence of different silicate concentrations on the growth of Thalassiosira sp. and determine the optimal silicate concentration for its growth. The method used is a laboratory experiment. Thalassiosira sp. microalgae were cultured with six different silicate concentration treatments: 0ppm, 5ppm, 10ppm, 15ppm, 20ppm, and 25ppm. The research results show that different silicate concentrations significantly affect (p&lt;0.05) the growth (cell density) of Thalassiosira sp. The optimal cell density of Thalassiosira sp. is observed at silicate concentrations of 15 ppm and 20 ppm, with peak densities of 70x105cells/mL and 75.7 x105 cells/mL on the 6th day, respectively. The lowest cell density is recorded at a silicate concentration of 0ppm, reaching a peak density of 42x105 cells/mL on the 6th day. Based on these results, it can be concluded that different silicate concentrations can be applied to enhance microalgal density. Throughout the study, water quality measurements were conducted, revealing temperature ranging between 22-25°C, salinity between 35-37ppt, and pH within the range of 8-8.5. The water quality used in the study remains optimal for the growth of Thalassiosira sp.

GIS-based hydrochemical assessment of groundwater in the Bakoya Massif, Northern Morocco

This research investigates the long-term and short-term toxicity of groundwater consumed by the population in a specific region, addressing the growing concern over groundwater pollution—particularly with heavy metals—as a significant environmental issue. The study conducts a comprehensive physicochemical analysis of water quality in the Bakoya massif, Al Hoceima, by examining thirty groundwater samples. Parameters such as pH, total dissolved solids (ranging from 559 to 3564 mg/l), and Electrical Conductivity (ranging from 747 to 4650 µS/cm) were measured. The fluoride concentration varied from 0.01 mg/l to 2.6 mg/l, surpassing the maximum allowable level of 1.5 mg/l for drinking water in Morocco in several samples. This study leverages GIS statistical analysis for hydrochemical distribution, providing insights into the mineralization processes affecting water quality. The findings highlight both natural and anthropogenic factors influencing the fluoride concentration, which remains within safe limits in most locations except for five wells. Additionally, arsenic and silicate concentrations were assessed, with arsenic exceeding the safe limit of 0.5 mg/l in two instances. This study underscores the critical need for ongoing monitoring and management of groundwater quality to safeguard public health and the environment.

Effect of silicon priming on germination and growth of rice (Oryza sativa L.) in drought condition

Drought in some agricultural areas due to global climate change is an obstacle in rice cultivation. ‘IR 64’ is one of the commonly grown rice cultivars but this cultivar is very susceptible to drought. Seed priming treatment with silicon is one way to increase rice resistance to drought stress. This study aimed to determine the effect of seed priming using calcium silicate on germination and growth responses of rice under drought condition. This study used two types of treatments. Silicon priming concentration and drought stress in a completely randomized experimental design. The concentration of calcium silicate (0, 1, 2 and 3 mM). Drought treatment with different field capacity (100%, 80%, 60% and 40%). The observed parameters were percentage and rate of germination, plant height, number of leaves and tillers, chlorophyll, and carotenoid levels. On the fifth day, the percentage of germination in the control, 1, 2 and 3 mM of silicon priming was 78.67%, 80%, 96% and 97.33%, respectively. Along with decreasing field capacity, rice plant growth decreases. Seed priming with calcium silicate showed a trend of increasing in percentage and rate of germination, plant height, number of leaves and number of tillers, chlorophyll dan carotenoid levels.

Targeted cultivation of diatoms in mariculture wastewater by nutrient regulation and UV-C irradiation.

Mariculture wastewater poses environmental challenges due to pollution and eutrophication. Targeted cultivation of diatoms in wastewater can help alleviate these issues while generating beneficial algae biomass, however reliable operating methods are lacking. We proposed a novel method for treating mariculture wastewater that employed UV-C irradiation and nutrient regulation to achieve targeted diatom cultivation. This study first examined growth of four diatom species (Nitzschia closterium, Chaetoceros muelleri, Cyclotella atomus, and Conticribra weissflogii) in mariculture wastewater. C. muelleri and C. weissflogii demonstrated better adaptability compared to N. closterium and C. atomus. Additionally, the growth and nutrient utilization of C. muelleri were studied under varying concentrations of silicate, phosphate, ammonium, and trace elements in wastewater. Optimal growth was observed at 500 μmol/L silicate, 0.6 mg/L phosphate, and 4 mg/L ammonium. Ammonium proved to be a more effective nitrogen source than urea and nitrate in promoting growth at this low level. Surprisingly, trace element supplementation did not significantly impact growth. Finally, this study utilized UV-C irradiation as a pre-treatment method for wastewater prior to nutrient adjustment, significantly enhancing the growth of C. muelleri. Overall, this study provides guidance on regulating key nutrients and pre-treatment method to optimize diatom biomass production from mariculture wastewater. This approach not only addresses environmental challenges associated with mariculture but also contributes to sustainable aquaculture practices through the recovery of valuable aquatic resources.

Inducing Fungal Pelletization Using Affordable Microparticle

Filamentous fungi have been known as one of the potential microorganisms in various industries. One of the isolates with great potential is Mucor irregularis that offer substantial potential to their growth characteristics. In submerged cultures, these microorganisms often aggregate into mycelia, enabling high-density cultivation and enhanced productivity. M irregularis have a high lipid content of 43.46% and a yield of 3.28 g/L. To further lipid-rich biomass production, pelletization is explored to involve the addition of microparticles like magnesium silicate and calcium carbonate. Microparticles have demonstrated the ability to control growth and enhance biomass in various strains. This study investigates the impact of microparticle addition on M. irregularis biomass production and pellet formation. Preliminary tests reveal that the addition of magnesium silicate microparticles (0, 1, 2, and 3 g/L) induces pellet formation, with the 2 g/L treatment yielding optimal results. Microscopic observations confirm that higher magnesium silicate concentrations result in more compact pellets. Biomass production peaks at 72 hours of incubation, reaching 3.09 ± 0.43 g/L, while the largest pellet diameter of 1.27 mm occurs at 48 hours of incubation. This research offers insights into enhancing biomass production and pellet formation in M. irregularis, holding promise for diverse applications.

LABORATORY INVESTIGATION OF THE EFFECT OF SODIUM SILICATE AND BENTONITE ON THE MECHANICAL PROPERTIES OF THE GROUT BEHIND THE SEGMENT IN MECHANIZED EXCAVATION

Nowadays, the use of Tunnel Boring Machines (TBM) in tunnelling has increased in urban environments. One of the effective parameters in the excavation process is the use of grout behind the segments to prevent ground settlement and penetration into the tunnel. The investigation of the effects of two-component grout (bentonite and sodium silicate) on the mechanical properties of the grout plays a crucial role in mechanized excavation. Therefore, this article aims to investigate the effect of various parameters on the properties of the two-component grout. Eight different mixing designs were considered in this research. Gel-time tests, viscosity test, water bleeding test, uniaxial compressive strength tests (UCS), and direct shear tests were conducted for each mixing design. The UCS tests were performed for eight mixing designs and at four different ages of the grout, while the direct shear test was conducted for five mixing designs at the age of one day. The results showed that increasing the sodium silicate content from 4% to 9.4% reduced the Gel-time to 7 seconds, and increasing the bentonite content from 2.3% to 4.58%, increased the marsh funnel time to 12 seconds. The uniaxial compressive strength of the grout increased to 0.682 MPa at the age of 28 days. Finally, by conducting the direct shear test on the grout and obtaining the parameters of cohesion and internal friction angle, it was determined that these two parameters depend on the values of bentonite and sodium silicate, and they change with the increase or decrease of these grout components.

COMPOSITE MIXTURES OF LIGNOSULFONATE REAGENT SYSTEMS WITH SILICON COMPOUNDS

The relevance of the article is related to the study of the possibility of improving the quality of lignosulfonate systems used during the passage of intervals of swelling clay rocks. A feature of reagent systems based on lignosulfonates is their ability to inhibit the hydration processes of clay minerals and thereby reduce the risks of complications during the construction of oil and gas wells. The properties of the composition were studied on the basis of a mixture of lignosulfonate systems and silicon compounds using the example of ferrochromolignosulfonate (FHLS-M) and sodium silicate Na2SiO3 (SS). The objective of the study was to find optimal ratios of the components of the mixture by the method of experimental planning, as a means of constructing mathematical models and regression analysis to assess the magnitude and direction of the impact of various factors on the output parameters of the flushing fluid system. The research method consists in determining the stability of the solution parameters with varying temperatures from 20 to 190 °C in the aging cell for 5 h and conducting at least three parallel determinations for each ratio of reagents in the composition relative to the initial clay solution. The performed regression analysis of the composition of FHLS-M: SS showed that the greatest influence on the viscosity and filtration properties of the solution is exerted by the content of FHLS-M. However, in the temperature range of 80-190 °C, the ratio of FHLS-M: SS is justified, equal to 3%:5% (the addition of SS enhances the effect of the composition by more than 40%). In the temperature range of 20-120 °C, to maintain the conditional viscosity of the solution (CV) at least 60 s, a sodium silicate content of about 4 % is required, FHLS-M – within 3-5%. At temperatures of 80-120 °C and a value of CV = 60 s, the composition of the composition of FHLS-M: SS is 3%:4%, respectively; with an increase in temperature of more than 120 °C, there is a need to increase the consumption of FHLS-M. At the same time, in the temperature range of 80-190 °C, the ratio of FHLS-M: SS is justified at the level of 3%:4%, respectively. It was found that the optimal ratio in the temperature range of 20-190 °C, in the composition of FHLS-M: SS, is 0.75%:0.75 %, respectively, however, the conditional viscosity (CV) of the solution is no more than 35 s. A decrease in the filtration index (FI) of the solution at temperatures up to 80 °C is ensured by the use of less than 2% sodium silicate in the composition, and FHLS-M in the range of 2-5%.

Workability and durability analysis of waste based geopolymer concrete

GPC as a promising material, started gaining momentous attention from the researchers and construction specialists because of its advantages in using by-products from agriculture and industries to replace cement thereby reducing greenhouse gas emission. Workability and durability tests were carried out, so as ascertain the efficiency of the rice husk ash and rice husk as sodium silicate and super plasticizer, for solving efflorescence problem known with geopolymer concrete. The factory-made sodium silicate was also used and compared with laboratory-produced, before addition of other geopolymer binders such as kaolin clay and fly ash. Brunauer-Emmett-Teller (BET) scrutiny that delivers quantitative data on the specific surface area as well as porosity dispersal of solid materials revealed that correlation coefficient of RHA (0.994) was higher than that of cement (0.991). Besides, RHA has higher surface area (250.023 m3/g) than the cement utilized which stood at 211.49 m3/g. Though the c constant of cement exceeds the RHA values, RHA can serve as good pozzolanic material and cement substitute. It is seen that the workability of laboratory-produced sodium silicate and superplasticizer geopolymer concrete was enhanced significantly compared to that of prior geopolymer systems. It is observed that the workability of the geopolymer concrete was considerably enhanced compared to that of orthodox geopolymeric systems, especially at 2.5% rice-husk created superplasticizer and higher content of laboratory-produced sodium silicate.

Lithology and oil content of the Bazhenov Formation in the central part of the Mansi Syneclise (Russia)

The article presents the results of studying four sections of the Bazhenov Formation and the overlying sediments in the central part of the Mansi syneclise, which are based on a comprehensive analysis of the results laboratory lithological and geochemical studies of core material and data from a wide range of geophysical studies of wells. For lithological characteristics, the section of the Bazhenov Formation was divided into five members, which differ in the ratio of carbonaceous, clayey, siliceous contents and carbonate component of rocks. The boundaries of the units were determined by their lithological composition, and then the velocity rectified taking into account GIS. The first two members are characterized by high contents of siliceous and clayey material, the third – a significant increase in the siliceous component, the fourth – increased concentrations of organic matter, which indicates its higher compared to the lower part section oil generation potential. In the fifth member, the content of carbonate material increases, the “coccolithic” interval is divided, and numerous fragments of bivalves are noted. Throughout the section minerals (strontianite, witherite) were discovered in the Bazhenov Formation, indicating that they occurred in diagenesis hydrothermal processes. In the section of one of the studied wells in the middle part of the Bazhenov formation, a reservoir interval was identified. High variability of reservoir properties of Bazhenov rocks was noted even within one oil-field, which is associated with their secondary transformations of rocks in dia- and catagenesis. It is substantiated, that materials of geophysical studies of wells that does not contain nuclear magnetic resonance data can only be used to identify possible productive intervals, the study of which by laboratory methods will allow establish the presence or absence of collectors in them.

Pore system and methane adsorption capacity features of marine and marine-continental transitional shale in the Sichuan Basin, SW China

Recently, significant achievements have been made in the gas exploration of marine Longmaxi shale in China. As exploration efforts have advanced, the exploration targets have gradually expanded to other sedimentary systems (marine-continental transitional and lacustrine). Compared with marine shale, shale in other sedimentary systems shows stronger heterogeneity, rendering previous exploration experiences of marine shale ineffective in guiding exploration efforts. Therefore, there is a pressing need for comparative studies to support future exploration practices. In this paper, the marine Longmaxi Formation and the marine-continental transitional Longtan Formation shales in the Lintanchang area of the southeastern of the Sichuan Basin are selected as the research objects. The study aims to compare the mineralogical characteristics, pore systems, and methane adsorption capacities of these two sets of shales, thereby revealing the differences in controlling factors that affect their physical properties and methane adsorption capacities. Our results show that the Longtan shale exhibits a higher clay mineral content, while the Longmaxi shale demonstrates significantly higher siliceous mineral content. Compare with Longmaxi shale, the Longtan shale exhibits a wider distribution range and higher average value of TOC content. The pore system in the Longmaxi shale is primarily dominated by organic matter-related pores, whereas the Longtan shale is characterized by clay mineral-related pores as the primary pore type. Given the variance in sedimentary environments, the controlling factors of physical properties differ significantly between the two sets of shales. In the case of the Longmaxi shale, TOC content is the most influential factor governing physical properties, while clay mineral content exerts the most significant influence on physical properties in the Longtan shale. Furthermore, TOC content emerges as the primary factor affecting methane adsorption capacity in both the Longmaxi and Longtan shales, despite the presence of significant variations in their pore systems. Nevertheless, the specific mechanisms through which TOC content impacts methane adsorption capacity exhibit variations between the two distinct shale types under investigation. The difference in sedimentary environment leads to various effects of mineral composition on methane adsorption capacity. Therefore, in the future research, the influences of different factors on methane adsorption capacity should be studied in combination with the sedimentary background.

Impact of Sodium Silicate Supplemented, IR-Treated Panax Ginseng on Extraction Optimization for Enhanced Anti-Tyrosinase and Antioxidant Activity: A Response Surface Methodology (RSM) Approach.

Ginseng has long been widely used for its therapeutic potential. In our current study, we investigated the impact of abiotic stress induced by infrared (IR) radiations and sodium silicate on the upregulation of antioxidant and anti-tyrosinase levels, as well as the total phenolic and total flavonoid contents of the Korean ginseng (Panax ginseng C.A. Meyer) variety Yeonpoong. The RSM-based design was used to optimize ultrasonic-assisted extraction time (1-3 h) and temperature (40-60 °C) for better anti-tyrosinase activity and improved antioxidant potential. The optimal extraction results were obtained with a one-hour extraction time, at a temperature of 40 °C, and with a 1.0 mM sodium silicate treatment. We recorded maximum anti-tyrosinase (53.69%) and antioxidant (40.39%) activities when RSM conditions were kept at 875.2 mg GAE/100 g TPC, and 3219.58 mg catechin/100 g. When 1.0 mM sodium silicate was added to the media and extracted at 40 °C for 1 h, the highest total ginsenoside content (368.09 mg/g) was recorded, with variations in individual ginsenosides. Ginsenosides Rb1, Rd, and F2 were significantly affected by extraction temperature, while Rb2 and Rc were influenced by the sodium silicate concentration. Moreover, ginsenoside F2 increased with the sodium silicate treatment, while the Rg3-S content decreased. Interestingly, higher temperatures favored greater ginsenoside diversity while sodium silicate impacted PPD-type ginsenosides. It was observed that the actual experimental values closely matched the predicted values, and this agreement was statistically significant at a 95% confidence level. Our findings suggest that the application of IR irradiation in hydroponic systems can help to improve the quality of ginseng sprouts when supplemented with sodium silicate in hydroponic media. Optimized extraction conditions using ultrasonication can be helpful in improving antioxidant and anti-tyrosinase activity.

Impact of anthropogenic accumulation on phytoplankton community and harmful algal bloom in temporarily open/closed estuary

Spatio-temporal variation in phytoplankton community dynamics in a temporarily open/closed Swarnamukhi river estuary (SRE), located on the South East coast of India was investigated and correlated to that of the adjacent coastal waters. Understanding the seasonal variability of the phytoplankton community and influencing factors are essential to predicting their impact on fisheries as the river and coastal region serve as the main source of income for the local fishing communities. Downstream before the river meets the sea, an arm of the Buckingham Canal (BC), carrying anthropogenic inputs empties into the Swarnamukhi River (SR1). The impact of anthropogenic effects on the phytoplankton community at BC was compared to other estuarine stations SR2 (upstream), SR1 (downstream), SRM (river mouth) and coastal station (CS). In BC station, harmful algal blooms (HABs) of Chaetoceros decipiens (2940 × 103 cells L−1) and Oscillatoria sp. (1619 × 103 cells L−1) were found during the southwest monsoon and winter monsoon, respectively. These HABs can be linked to the anthropogenic input of increased nutrients and trace metals. The HABs of Oscillatoria sp. were shown to be induced by elevated concentrations of nitrate (10.18 µM) and Ni (3.0 ppm) compared to ambient, while the HABs of C. decipiens were caused by elevated concentrations of silicate (50.35 µM), nitrite (2.1 µM), and phosphate (4.37 µM). Elevated nutrients and metal concentration from the aquaculture farms, and other anthropogenic inputs could be one of the prime reasons for the recorded bloom events at BC station. During this period, observed bloom species density was found low at other estuarine stations and absent at CS. The formation of bloom events during the closure of the river mouth could be a major threat to the coastal ecosystem when it opens. During the Osillatoria sp. bloom, both the Cu and Ni levels were higher at BC. The elevated concentration of nutrients and metals could potentially affect the coastal ecosystem and in turn fisheries sector in the tropical coastal ecosystem.