Monosilicic Acid Research Articles

Ammonium nutrition enhances rhizosphere mobilization and uptake of silicon in white lupin grown in low phosphorus soil

Abstract Background and Aims While nitrogen (N) supply can enhance plant silicon (Si) accumulation, the mechanisms by which different forms of N affect Si mobilization in the rhizosphere are not well understood. This study aims to elucidate how pH changes induced by ammonium (NH4+) and nitrate (NO3−) affect Si availability in the rhizosphere, especially under low phosphorus (P) conditions. Methods White lupin (Lupinus albus) plants were grown in non-fertilized low-P soil, supplied with a low dose of N, either as NH4+ or NO3−, with or without supply of monosilicic acid. We measured Si levels in various rhizosphere soil pools, along with different plant and rhizosphere soil parameters. Results The addition of NH4+ significantly lowered rhizosphere pH and decreased both Si adsorbed to pedogenic Fe/Mn oxides and amorphous phytogenic Si, resulting in higher concentrations of plant available Si in the white lupin rhizosphere. This led to greater Si uptake and improved plant growth compared to both the –N and + NO3− treatments. The supply of Si further enhanced these effects, with NH4+ showing a consistently different pattern of influence compared to NO3−. Additionally, –N white lupin plants accumulated more P than those treated with N, while Si supply significantly improved P acquisition across all treatments. Conclusions Our study demonstrates that rhizosphere acidification induced by NH4+ nutrition can significantly enhance Si mobilization from the rhizosphere soil in the absence of Si supply and reduce Si adsorption when Si is applied. These findings may have practical implications for improving both Si mobilization in the rhizosphere and the effectiveness of Si fertilizers.

Preparation of PU/SiO2 composite shell microencapsulated phase change materials with high thermal stability and thermal conductivity

To address the issues of poor thermal stability and thermal conductivity in polyurethane (PU) shell microencapsulated phase change materials (MEPCMs), this study prepared PU/SiO2-MEPCMs using an interfacial polymerization method combined with electrostatic self-assembly technology. First, the PU shell was synthesized via an interfacial polymerization reaction between isophorone diisocyanate (IPDI) and triethanolamine (TEA). Subsequently, the hydrolyzed product of tetraethyl orthosilicate (TEOS), monosilicic acid (Si (OH)4), was adsorbed onto the PU shell surface using electrostatic self-assembly technology and reacted with the –NCO groups to form an SiO2 shell. The effects of the PU/SiO2 composite shell on the surface morphology, chemical structure, compactness, thermal stability, phase transition performance, thermal conductivity, and thermal cycling stability of MEPCMs were investigated. The results showed that the formation of the PU/SiO2 composite shell significantly improved the thermal stability, compactness, thermal conductivity, and cyclic stability of MEPCMs. After continuous treatment at 150°C for 120 min, the leakage rate of the core material decreased from 12.13 % to 3.74 %, and the heat-resistant temperature (T95 %) increased by 30°C. Even after 1000 thermal cycles, MEPCMs still exhibited excellent heat storage performance. Additionally, even under high temperature conditions of 257°C (where pure butyl stearate completely decomposes), the PU/SiO2-MEPCMs still maintained a stable core-shell structure. The introduction of the SiO2 shell greatly enhanced the thermal conductivity of MEPCMs, aligning the phase change temperature more closely with that of the core material and effectively reducing the supercooling phenomenon. Furthermore, the stable energy storage system formed by MEPCMs on the finished fabric surface can endow it with excellent temperature regulation functionality.

Impact of silicon-enriched plant biostimulant treatment on shelf-life of baby spinach (Spinacia oleracea) crops

This research presents the findings from a series of experiments to assess and quantify the influence of compostable plastic packaging in combination with silicon biostimulant on waste produced in a typical leafy horticultural product. The research was conducted firstly by using an agricultural biostimulant consisting in varying supplementation with monosilicic acid, performed in 16 blocks with 3 different treatments and compared against the control samples. In addition, Equilibrium Modified Atmosphere Packaging (EMAP) packaging was designed using polypropylene (OPP) and compostable polylactic acid (PLA) films in order to assess the effect of potential mitigation of food waste production in combination with sustainable films. Storage studies were conducted to assess the amount of product that would run out of specification across a usability period of 7 days as an estimation of waste. The results show that 1 % waste was produced with OPP and no-mitigation, experiments showed a potential waste of 26 % using compostable films. The silicon-based supplementation managed to reduce waste by an average of 35 % in the case of the use with PLA. The results of this study establish a potential pathway for transition towards sustainable films in short shelf-life horticultural products using bio-stimulants with controlled dependents on EMAP.

The usage of silicon-humic preparations in the potato cultivation

One of the ways to increase crop yields is the use of foliar treatments with humic preparations. The purpose of the research is to study the effect of silica-humic preparations on the yield of potatoes and changes in soil characteristics. In the experiment, the effect of the humic preparation BoGum and the silicic-humic preparations BoGum-S and nanoBoGum-S obtained on its basis on the yield of potatoes of the Skarb variety and the agrochemical parameters of the soil was studied. The experiment was carried out on soddy-podzolic soil in 2020-2022. at the Gubino VNIIMZ agricultural polygon in the Tver region. The preparations were used for the treatment of tubers and double foliar feeding of vegetative potato plants. Background - mineral fertilizers (N65P65K65). It was shown that all preparations contributed to the increase in the yield of potato tubers, mainly due to an increase in the mass of marketable tubers. The increase in potato yield from the use of BoGum and BoGum-S was almost the same and averaged 4.5% over three years, the use of nanosized nanoBoGum-S gave an increase of 10.6%. The years of research were distinguished by unfavorable weather conditions (2020 - excessively humid, 2021 - dry, 2022 - slightly dry). The increase in potato yield showed that the preparations reduced the impact of unfavorable abiotic factors. In the flowering phase of potatoes, a decrease in the content of monosilicic acids and an increase in polysilicic acids in the soil were noted in the variants with the use of silicic preparations compared with the control. In addition, when using all preparations, the accumulation of mobile phosphorus in the soil was observed on average by 9-19 mg/kg of soil.

The mechanism of silica and transparent exopolymer particles (TEP) on reverse osmosis membranes fouling

Dissolved silica and transparent exopolymer particles (TEP) are the primary foulants in reverse osmosis (RO) desalinated brackish water and wastewater. In this study, we investigated the fouling properties of varying silica concentrations with TEP on the membrane surface and discovered a synergistic fouling effect between the silanol group (Si–OH) and the TEP carboxyl group (-COOH). The membrane fouling experiments showed that silica fouling approached saturation at 6 mM, with little variation in membrane flux as the silica concentration increased. Furthermore, the –OH functional group of the monosilicate molecule can chemically react with the -COO- functional group on the membrane surface to create hydrogen bonds, allowing monosilicate deposition directly on the membrane. Silica-silica interactions reacted with aggregates at high silica concentrations and joined with TEP to create a more substantial, more complex cross-linked network, resulting in severe membrane fouling. At pH 9, silica fouling was most severe due to the dramatic increase in the solubility of monosilicic acid dissolution in solution and the decreased polymerization rate. This work reveals the essential process of membrane fouling induced by silica and TEP, significantly increasing knowledge on silica-TEP fouling.

Geochemical study on the deposition of silica scale at Olkaria well OW-35: A key to understanding the formation mechanisms of silica scale at the Olkaria Geothermal Field, Kenya

In the Olkaria geothermal field, Kenya, a silica scale formed from geothermal water at the OW-35 production well was geochemically investigated. The geothermal water is highly alkaline, with a pH of 10.13, while the salinity is low, with a total Cl concentration of 432.4 ppm. The silica scale was precipitated from geothermal water with a high temperature (150–190 °C) in the OW-35 separator. For the mineral composition of the scale sample, it is mainly amorphous Opal-A and crystalline quartz. The SiO2 content was 85.47 wt.%, and the Al2O3 and Fe2O3 contents were high at 3.16 and 1.11%, respectively, despite the fact that Al and Fe concentrations in the geothermal water were low. Based on the enrichment factor, Al was extremely concentrated from the geothermal water onto the silica scale during the formation, suggesting that Al may participate in the formation of the silica scale. For Fe, there was no contribution of Fe to the formation of silica scale, which was present as magnetite. This silica scale is a mixture of crystalline quartz and amorphous opal-A. The deposition mechanism was considered as follows. The quartz was formed by continuous and slow adsorption of monosilicic acid on the surface of the solid due to the slight supersaturated condition. On the other hand, opal-A was formed by a reaction between aluminate ion and monosilicic acid or monosilicate ion on the solid surface.

Effects of biostimulants on the morphological growth of cocoa seedlings at the nursery stage

Biostimulants help cocoa plants to improve vegetative development and nutrient uptake, therefore, the objective was to evaluate the effects of biostimulants on morphological growth in cocoa seedlings in nursery stage, through a completely randomized experimental design with four treatments (T1: control, T2: humic acids + fulvic acids, T3: silicon oxide + monosilicic acid; and T4: marine algae + humic and fulvic acids) and four replicates. The results showed no significant differences in variables such as plant height (T4: 29.63 cm), number of leaves (T2: 25.19) and root length (T2: 37.23 cm). Significant differences were found in stem diameter (T3: 7.08 cm) and root dry mass (T4: 8.67 g). The biostimulants showed positive results in nutritional elements at foliar level, improving the values of N, P, K, Zn, Mn, Mg, Ca and Fe. Likewise, there was a decrease in Cu and Na values. These results support the hypothesis that biostimulants help cocoa plants to improve vegetative development and nutrient uptake, reducing plant losses and improving plant nutrition at the nursery stage.

Effect of Iron and Silicon on Growth and Yield of Sorghum (Sorghum bicolor L.)

The present study highlights the effect of Iron and Silicon on growth and yield of Sorghum (Sorghum bicolor L.). Si occurs primarily in soil solution as monosilicic acid (H4SiO4) at concentrations ranging from 0.1 to 0.6 mm and is taken up by plants in this form. Silicon can mitigate the negative effects of abiotic stresses such as high temperature, freezing, drought, lodging, radiation, irradiation, and UV, as well as chemical stresses such as salt, nutrient imbalance, and metal toxicity. A field experiment was conducted during Zaid season 2022 at experimental field of Crop Research Farm, Department of Agronomy, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India. The soil at the test site had a sandy loam texture, a pH of 7.3 that was almost neutral, and low levels of available potassium (215.4 kg/ha), nitrogen (230 kg/ha), phosphorus (13.60 kg/ha), and organic carbon (0.48%). The treatments consist of foliar spray of iron (0.5, 1.0, 1.5 %) at 35, 45 DAS and Foliar spray of Silicon (0.5, 1.0, 1.5 ml/L) at 50 DAS along with control (RDF: 80:40:40 NPK Kg/ha). The experiment was layout in Randomized Block Design with ten treatments each replicated thrice. Significantly higher plant height (205.66 cm), maximum plant dry weight (133.2 g) and the yield attributes namely test weight (25.82 g), grains/earhead (2368.33), grain yield (2850.00 Kg/ha), stover yield (4004.67 Kg/ha), maximum gross return (84645.00 INR/ha), net return (52313.00 INR/ha) and benefit cost ratio (1.61) were obtained in the treatment 9 with the application of 1.50% Iron along with 1.50ml/L Si.

ROLE OF ENVIRONMENTAL SILICA IN BIOLOGICAL AND MICROBIAL STRESS MANAGEMENT FOR CROP PRODUCTION

The most prevalent mineral in the earth's mantle is silicon, which ranks second only to oxygen, but unlike oxygen, it has not been shown to be necessary for plant development. Plants can only absorb silicon in one of two forms: silicic acid (Si (OH) 4) or mono silicic acid (H4 SiO4), neither of which is found in the planet's crust as silicon dioxide (SiO2). Silicon fertilizer has been shown toboost agricultural output and sustainability, and its use has been met with widespread praise. When water is lost via the stomata of a plant, the gel that has been polymerized from the silicon solution in the roots is precipitated out of solution. It has been shown that polymerized gel has no significant part in the physical functions of the plant system. This article reviews the function that silicon in soil, water, and plants plays in protecting ecosystems against abiotic and biotic pressures. The interplay between silicon, plant species, and environments is nuanced.

Silicon-mediated regulation of cadmium transport and activation of antioxidant defense system enhances Pennisetum glaucum resistance to cadmium stress

Pennisetum glaucum is an important forage grass for livestock. However, the large accumulation of cadmium (Cd) in plant tissues increases the risk of heavy metals entering the food chain in Cd-contaminated soils. Silicon (Si) can inhibit cadmium (Cd) uptake and enhance tolerance of plant to Cd toxicity, but whether and how Si alleviates Cd toxicity in grass and the underlying mechanisms are unclear. The present study explored the differential mechanisms of silicon-induced Cd transport in apoplast and symplast, Cd distribution in root tissue and antioxidant defense system in P. glaucum under Cd stress through hydroponic and pot experiments. The present results showed that exogenous Si supply significantly reduced Cd concentrations in apoplast and symplast; Si treatment increased monosilicic acid concentration in apoplast and symplast of the roots and shoots under Cd stress. Elemental analysis of root microdomains showed that Si treatment increased the distribution of Cd and Si in the endodermis by 42.6% and 14.0%, respectively. Si alleviated the adverse influences of Cd on plant growth, which were manifested in root morphological traits and root activity. In addition, Si addition significantly increased the activities of catalase and superoxide dismutase by 37.0% and 72.7%, and improved the efficiency of the ascorbate-glutathione cycle in Cd-stress shoots. Furthermore, Si significantly reduced the contents of hydrogen peroxide and superoxide anion in Cd-stressed shoots by 16.6% and 48.7%, respectively. These findings demonstrate that Si enhances the resistance of P. glaucum to Cd stress through regulating Cd transport pathways and activating antioxidant defense systems.

Новые материалы на основе природных кремнийсодержащих минералов и их использование для ремедиации загрязненных углеводородами почв

Silicon (Si)-rich minerals are widely used in agriculture and ecology, in particular, for remediation of contaminated soils and restoration of soil fertility. But natural minerals are commonly low efficient, resulting in high application rate. The performance of Si-based materials is largely determined by the supply of active Si forms, primarily water-soluble monosilicic acid. The effect of different modes of heat treatment on the efficacy of zeolite, diatomite and marl as a source of active Si forms was studied. Heating at 500 – 700 °С provided sharp increase in the water- and acid-extractable Si. The highest increases were observed at 30 min heating at 500 °С and 15-min heating at 700 °С. A further increase in temperature up to 1000оС or at heating time more than 15 min at 700 °С led to decreasing active Si. In vegetation test conducted with sand polluted by mixture of used engine oil and diesel fuel, heat-activated marl (EcoFlora) facilitated a decrease in petroleum hydrocarbons from 3 to 0.5 % over 4 weeks. In addition, the wheat tolerance to hydrocarbon-induced toxicity was enhanced, which was evidenced by increased seed germination from 35 to 85 %, plant weight (by 200 – 500 %), and the content of photosynthetic pigments in wheat leaves (by 20 – 40 %).

Silicon and plant nutrition—dynamics, mechanisms of transport and role of silicon solubilizer microbiomes in sustainable agriculture: A review

Silicon (Si) is the second most abundant element in the Earth's crust and has numerous roles in both soils and plants, although it is inaccessible to plants in its native state (insoluble silicate minerals). This inaccessibility can lead to insufficiency, which induces anomalies in plant growth and development. Specifically, Si alleviates various biotic and abiotic stresses in plants by enhancing tolerance mechanisms at different stages of uptake/deposition as a monosilicic acid. Exclusive utilization of conventional silicon (Si) fertilizers to boost agricultural productivity in an attempt to meet the world's ever-increasing food demand may result in surface and ground water pollution, waterway eutrophication, soil fertility depletion, and the accumulation of hazardous elements such as arsenic (As) in the soil. By addressing the drawbacks of chemical fertilizers, this review emphasizes an environmentally friendly alternative, namely , silicon-solubilizing microbiomes (SSMs), as bio-inoculants to liberate soluble Si and thus making it available to plants. A deep understanding of recent advances in the functional diversity, colonization patterns, modes of action, role in biogeochemical cycling, and phyto-stress tolerance for SSMs, and their implementation in Si-based agro-waste management through the fabrication of nanoparticles, could help to establish a reliable tool for economically and environmentally sustainable agriculture. From this perspective, in this review, we comprehensively summarize the latest methodologies for the isolation, screening, and characterization of SSMs, and Si solubilization mechanisms, including ligands (divalent cations), acids (inorganic and organic), alkali (nucleophilic attack), extracellular polysaccharides, and factors affecting them, as well as Si-mediated regulation of gene expression involved in Si uptake, transportation, and mineralization. We have critically revised the role of silicon-solubilizing microbes according to the current literature. The contributions of SSMs to bio-fertilization are still being explored; hence, we also discuss trajectories for future research in relation to SSM-mediated increases in bio-available Si. This will create new strategies by which to reduce the use of agrochemicals, improve plant health, and help us to globally gravitate towards more sustainable agricultural practices, based on the concept of a circular economy.

Silicon nanoparticles in higher plants: Uptake, action, stress tolerance, and crosstalk with phytohormones, antioxidants, and other signalling molecules

Silicon is absorbed as uncharged mono-silicic acid by plant roots through passive absorption of Lsi1, an influx transporter belonging to the aquaporin protein family. Lsi2 then actively effluxes silicon from root cells towards the xylem from where it is exported by Lsi6 for silicon distribution and accumulation to other parts. Recently, it was proposed that silicon nanoparticles (SiNPs) might share a similar route for their uptake and transport. SiNPs then initiate a cascade of morphophysiological adjustments that improve the plant physiology through regulating the expression of many photosynthetic genes and proteins along with photosystem I (PSI) and PSII assemblies. Subsequent improvement in photosynthetic performance and stomatal behaviour correspond to higher growth, development, and productivity. On many occasions, SiNPs have demonstrated a protective role during stressful environments by improving plant-water status, source-sink potential, reactive oxygen species (ROS) metabolism, and enzymatic profile. The present review comprehensively discusses the crop improvement potential of SiNPs stretching their role during optimal and abiotic stress conditions including salinity, drought, temperature, heavy metals, and ultraviolet (UV) radiation. Moreover, in the later section of this review, we offered the understanding that most of these upgrades can be explained by SiNPs intricate correspondence with phytohormones, antioxidants, and signalling molecules. SiNPs can modulate the endogenous phytohormones level such as abscisic acid (ABA), auxins (IAAs), cytokinins (CKs), ethylene (ET), gibberellins (GAs), and jasmonic acid (JA). Altered phytohormones level affects plant growth, development, and productivity at various organ and tissue levels. Similarly, SiNPs regulate the activities of catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), and ascorbate-glutathione (AsA-GSH) cycle leading to an upgraded defence system. At the cellular and subcellular levels, SiNPs crosstalk with various signalling molecules such as Ca2+, K+, Na+, nitric oxide (NO), ROS, soluble sugars, and transcription factors (TFs) was also explained.

The Cd sequestration effects of rice roots affected by different Si management in Cd-contaminated paddy soil

The application of exogenous silicon (Si) reportedly is one of the eco-friendly practices to mitigate cadmium (Cd) phytotoxicity and regulate the chemical behaviors of Cd in the soil-rice system. But the efficiency of Si on the Cd retention by rice root varies with the Si fertilizer management. The objective of this paper was to interpret the differences in Cd immobilization by rice roots and relevant mechanisms under different ways of Si application (T-Si, supplied at transplanting stage; TJ-Si, split at transplanting and jointing stage with the ratio of 50 % to 50 %; J-Si, supplied at jointing stage and CK, none of Si application) in Cd-contaminated paddy soils. The results showed that the Cd-retention capacity of rice root was increased by 0.60 % ~ 3.06 % under different Si management when compared to CK. The concentrations of monosilicic acid in soils and in apoplast and symplast of roots were increased significantly by Si application, while Cd concentrations in apoplast and symplast of root were decreased by 28.50 % (T-Si), 40.64 % (TJ-Si) and 30.26 % (J-Si), respectively. The distribution of Cd in rice cell wall was increased significantly by TJ-Si. The Cd concentrations of inert fractions (F3, F4 and F6) in root of TJ-Si were raised obviously. Si application downregulated the expression of OsIRT2 and OsNramp5 while upregulated OsHMA3, and the expression of OsHMA3 treated by TJ-Si was obviously higher than CK and J-Si. The distributions of the passive Cd in roots bound with thiol compounds (NPT, GSH and PCs) and polysaccharide components (pectin, hemicelluloses 1 and hemicellulose 2) were raised much more by TJ-Si than by T-Si and J-Si. On the whole, compared with T-Si and J-Si, TJ-Si could more easily replenish soil available Si and enhance Cd sequestration in roots as the result of the decrease of Cd transport factor in roots. This study unravels some mechanisms about different Si management on increasing Cd retention and decreasing Cd migration in rice roots, and TJ-Si is worthy of being recommended.

Precipitation behavior of iron and silicic acid when mixing acidic and weakly alkaline geothermal waters at the Hatchobaru geothermal power plant, Oita, Japan

This study investigated the precipitation behavior of silicic acid (Si) and iron (Fe) when acidic and weakly alkaline geothermal waters were mixed at various mixing ratios (R) (the proportion of the acidic geothermal water, which ranged from 1 to 9) at 85 ˚C under an oxidizing atmosphere at the Hatchobaru Geothermal Power Plant in Japan. The pH and total Fe concentration of the acidic and weakly alkaline geothermal waters were 2.8 and 8.7 at 25 ˚C and 6.5 and 0.5 ppm, respectively. The pH of the mixed geothermal waters at 85 ˚C ranged from 8.11 to 3.30. Although Si precipitated after they were mixed at R of 1 to 4, Fe precipitated immediately after mixing, independent of R. The amount of Fe precipitated also increased with increasing R (thus increasing the Fe initial concentration). The precipitates were divided into two groups based on their chemical composition: those with a high Si/Fe atomic ratio in the range of 100 to 150, found at R of 1 to 4, and those with a Si/Fe atomic ratio lower than 10, found at R of 5 to 9. Silicic acid polymerized after they were mixed at R between 1 and 3 and the polymerization was not observed at R above 4. Fe was present as colloidal hydrous ferric oxide (HFO) and hydrolyzed species of Fe3+ in the acidic geothermal water. From these results, it may be concluded that the precipitates with a high Si/Fe atomic ratio were formed due to the aggregation of polysilicic acid particles with Fe at R from 1 to 3, whereas the precipitates with low Si/Fe atomic ratios were formed owing to the aggregation of HFO bonding monosilicic acid because of the sudden increase in pH at all R. There was a large amount of precipitate (the sum of Fe and Si mmol) at R from 1 to 4, indicating that delaying the polymerization of the silicic acid is key in preventing large precipitation of Si and Fe. Judging from the saturation indices for minerals commonly found in geothermal fields, the amorphous precipitates with high and low Si/Fe atomic ratios may be precursors of silica polymorph and nontronite as a Fe(III) silicate because they can be formed at R from 1 to 9.

Co-treatment with silicon and quicklime in pig manure application as a promising option of environmnetal management

Manure utilization is the most important current practices economically and, ecologically. The combined use of active forms of silicon together with other types of soil amendments or fertilizers has been shown to reduce P, N and K leaching from upper soil horizon or fixation, which positively affect crop production. The present study evaluated the performance of pig manure co-treated with quicklime (calcium oxide - CaO) and monosilicic acid (Si(OH)4) as sources of nutrients for rice production conducted in greenhouse and field tests for the reduction of negative environmental effects through the soil-plant system. Results indicated that quicklime/monosilicic acid-treated pig manure reduced the phosphorus and potassium leaching and phosphorus fixation which resulted in an increase in the biomass of rice by 38.3–52.3% in greenhouse and rice yield in field increased by up to 17.4%. Phosphorus plant-availability in the soil and its uptake by rice plants were enhanced by the mixture of treatments. Furthermore, quicklime/monosilicic acid -treated pig manure enhanced the accumulation of potassium in rice leaves.

Microbial Growth in Shrimp Ponds as Influenced by Monosilicic and Polysilicic Acids

In order to increase shrimp production and minimize detrimental environmental impacts of aquaculture, the maintenance and regulation of the growth and composition of phytoplankton communities and nutritional balance are critical. Silicon (Si) is an essential nutrient for diatoms and other types of microorganisms, but the information about the Si impact on their growth is extremely scarce. Monosilicic and polysilicic acids were tested in several shrimp cultivation systems in Jiangsu Province, China. In pond waters, the concentrations of monosilicic and polysilicic acids were sharply reduced by 36-95% and 35-75%, accordingly, as compared with those in supply water sources. The microbial cell abundance was strongly dependent on monosilicic acid. In laboratory experiments, monosilicic acid added to pond water or probiotic solutions at 1- and 2-mM Si had a significant positive effect on cell abundance. Over three days, the concentrations of monosilicic acid decreased by 81 to 91% in pond water and by 11 to 24% in probiotic solution. In probiotic solutions, the degree of polymerization of silicic acid was more intensive than that in shrimp pond waters. The data obtained demonstrates the importance of systematic studies related to the functions of Si in shrimp aquaculture.

Impact of the application of monosilicic acid to grapevine (Vitis vinifera L.) on the chemical composition of young red Mencia wines

Impact of applying monosilicic acid to grapevines during ripening on chemical composition of Mencía red wines in an area where fungal diseases during summer are common was examined. The foliar application of monosilicic acid to grapevines led to a less oxidized wine, with lower levels of acetic acid, acetaldehyde, ethyl acetate and diacethyl; this should be considered as positive from a sensory point of view. Wines made with silicon-treated grapes also contained lower levels of gluconic acid and glycerol, which are chemical markers of wines made with botrytized grapes, as well as higher contents of total phenols, anthocyanins and tannins. Furthermore, the contents of several mid-chain alcohols were higher (p < 0.05) in wines made with grapes from silicon-treated plants.

Synthesis of mesoporous silica from geothermal water

Mesoporous silica was successfully synthesized for the first time using geothermal water from the Onuma Geothermal Power Plant, Akita Prefecture, Japan. Cetyltrimethylammonium bromide (CTAB) was used as an organic template for the synthesis. CTAB with a concentration of 2.4 × 10–4 mol/L was reacted for 30 min with geothermal water at a temperature of 90 °C, which had a total silicic acid concentration of 475 mg/L (SiO2), at pH 7.0, pH 8.2 (raw water) and pH 9.0. By calcination of the resulting precipitate at 550 °C, mesoporous silica with a pore size of about 2.8 nm and a specific surface area of > 800 m2/g was formed. The total silicic acid concentration in the solution after formation of the mesoporous precipitates was reduced to < 280 mg/L, indicating efficient recovery of supersaturated silicic acid from geothermal water. The monosilicic acid in geothermal water plays an important role in the formation of mesoporous silica. Production of mesoporous silica by our method will contribute not only to prevention of silica scale formation in the piping systems of geothermal power plants but also to its use as an industrial resource.

Silicon substances for restoration of oil-contaminated areas

Numerous investigations demonstrate that active forms of silicon (Si) enhance the plant tolerance against abiotic stresses by several mechanisms, including increasing the antioxidant activities and minimizing oxidative damage. Soil contamination with oil and oil products relates to abiotic stress that detrimentally affects soil microbial population and plant growth. Considering the crucial role of microorganisms and plants in bioremediation of oil-polluted areas, Si substances can be beneficial to acceleration of soil reclamation. In greenhouse experiment, wheat was grown in Grey Forest Soil contaminated with used motor oil. The effect of fumed silica and monosilicic acid on soil enzymatic activity and plant growth was studied. Both Si substances provided increasing the plant biomass and the activities of catalase and dehydrogenase. As regards the plant growth, the effect of Si was more pronounced in polluted soil, while the enzyme activity was higher affected in unpolluted soil. The activities of catalase and dehydrogenase were closely correlated to the water-soluble Si in soil (R=0.91-0.92). Silicon substances with high content of, plant-and microorganism-available Si might be promising for involvement in bioremediation technology for oil-contaminated soil.