Increase In Phosphorus Content Research Articles

Abiotic processes control carbon dioxide dynamics in temperate karst lakes.

Inland waters are crucial in the carbon cycle, contributing significantly to the global CO2 fluxes. Carbonate lakes may act as both sources and sinks of CO2 depending on the interactions between the amount of dissolved inorganic carbon (DIC) inputs, lake metabolisms, and geochemical processes. It is often difficult to distinguish the dominant mechanisms driving CO2 dynamics and their effects on CO2 emissions. This study was undertaken in three groundwater-fed carbonate-rich lakes in central Spain (Ruidera Lakes), severely polluted with nitrates from agricultural overfertilization. Diel and seasonal (summer and winter) changes in CO2 concentration (CCO2) DIC, and CO2 emissions-(FCO2)-, as well as physical and chemical variables, including primary production and phytoplanktonic chlorophyll-a were measured. In addition, δ13C-DIC, δ13C-CO2 in lake waters, and δ13C of the sedimentary organic matter were measured seasonally to identify the primary CO2 sources and processes. While the lakes were consistently CCO2 supersaturated and FCO2 was released to the atmosphere during both seasons, the highest CCO2 and DIC were in summer (0.36-2.26 µmol L-1). Our results support a strong phosphorus limitation for primary production in these lakes, which impinges on CO2 dynamics. External DIC inputs to the lake waters primarily drive the CCO2 and, therefore, the FCO2. The δ13C-DIC signatures below -12‰ confirmed the primary geogenic influence on DIC. As also suggested by the high values on the calcite saturation index, the Miller-Tans plot revealed that the CO2 source in the lakes was close to the signature provided by the fractionation of δ13C-CO2 from calcite precipitation. Therefore, the main contribution behind the CCO2 values found in these karst lakes should be attributed to the calcite precipitation process, which is temperature-dependent according to the seasonal change observed in δ13C-DIC values. Finally, co-precipitation of phosphate with calcite could partly explain the observed low phytoplankton production in these lakes and the impact on the contribution to increasing greenhouse gas emissions. However, as eutrophication increases and the soluble reactive phosphorus (SRP) content increases, the co-precipitation of phosphate is expected to be progressively inhibited. These thresholds must be assessed to understand how the CO32- ions drive lake co-precipitation dynamics. Carbonate regions extend over 15% of the Earth's surface but seem essential in the CO2 dynamics at a global scale.

The urgent need to reduce phosphorus discharges for sustainable mangrove wetland management

Phosphorus affects microbial metabolic activity, nitrogen and carbon cycling in mangrove sediment, but its influence on carbon stability and greenhouse gases emission remains unclear. This study compared greenhouse gases (CO2, N2O, and CH4) emissions from mangrove sediment receiving wastewater containing various phosphorus concentrations, and evaluated its long term effect on sediment carbon flux when phosphorus pollution is eliminated. Significant increases in greenhouse gases flux and decrease of total organic carbon and readily oxidizable organic carbon in the sediment were observed after phosphorus discharge. Specifically, the N2O flux was reduced significantly at high phosphorus levels while the CO2 flux and the microbial biomass organic carbon was increased. The copy numbers of ammonia oxidation (AOA-amoA, AOB-amoA) gene, denitrification (narG, nirK) gene and methanogenesis (mcrA) gene increased with the increasing phosphorus concentration. During the wastewater discharge period for 70 days, the global warming potential of sediment flux at high phosphorus discharge condition was more than 4 times that of the control group, and the loss of total organic carbon and readily oxidizable organic carbon was 4.66 % and 7.1 %, respectively. During the remediation period (71–101 days), the greenhouse gases flux decreased rapidly, ends up with a similar level of the control group. Our results indicate that using mangrove wetland for pollution minimization in the coastal aquaculture industry could increase greenhouse gases emisison significantly, it is therefore essential to reduce phosphorus discharges from various anthropogenic activities, and local authorities must set up more stringent discharge standards in the future.

Chronic increasing nitrogen and endogenous phosphorus release from sediment threaten to the water quality in a semi-humid region reservoir

The water quality in the drinking water reservoir directly affects people's quality of life and health. When external pollution input is effectively controlled, endogenous release is considered the main cause of water quality deterioration. As the major nitrogen (N) and phosphorus (P) sources in reservoirs, sediment plays a vital role in affecting the water quality. To understand the spatial and temporal variation of N and P in the sediment, this study analyzed the current characteristics and cumulative effects of a semi-humid reservoir, Yuqiao Reservoir, in North China. The N and P concentrations in the reservoir sediment were decreased along the flow direction, while the minimum values were recorded at the central sediment profile. External input and algal deposition were the main factors leading to higher sediment concentrations in the east (Re-E) and west (Re-W) areas of reservoir sediment profiles. According to the long-term datasets, the peaks of both sediment total nitrogen content and deposition rate were observed in the 2010s, which has increased about three times and six times than in the1990s, respectively. Therefore, the increase in phosphorus concentration may be the main reason for eutrophication in water in recent years. The mineralization of organic matter has a significant promoting effect on releasing N and P from sediments, which will intensify eutrophication in water dominated by P and bring huge challenges to water environment management. This study highlights that the current imbalance in N and P inputs into reservoirs and the endogenous P release from sediment will have a significant impact on water quality.

Short-term effect of no-tillage management on the chemical attributes and bacterial diversity in soils in an organic production system

No-tillage (NT) has been adopted in organic agriculture as an alternative to conventional tillage (CT) for improving soil conservation. Cover crops (CC) play a vital role in this process by providing straw and releasing nutrients into the soil. Therefore, in this study, we aimed to evaluate the effects of NT and CT management on the chemical properties and bacterial diversity of soil following the cultivation of diverse CC in an organic system. The experiment was conducted using a randomized block design with subdivided plots, wherein the plots represented CT and NT, and the subplots represented the diverse CC tested, including pearl millet, sunn hemp, jack bean, seed mixes 1 and 2 (containing 100 % and 50 % of the recommended seeding rates for each crop), and spontaneous plants. The evaluations were conducted one year after the experiment was conducted. The results demonstrated that NT promoted increases in soil magnesium, phosphorus, and organic carbon contents, including increased bacterial richness. Moreover, NT resulted in a higher abundance of Bacteroidetes, GAL15, and Myxococcota. Conversely, CT favored a greater relative abundance of Actinobacteria, in addition to the members of Bacteroidetes. Regarding the influence of CC, no significant differences were observed in the diversity and structure of the bacterial communities, except for subgroup 17, which was more abundant in spontaneously grown plants. NT proved to be more effective than CT in improving soil chemical properties and bacterial diversity, implying its potential to contribute to sustainable agricultural systems.

The Enhanced Adsorption Capacity of Ziziphus jujuba Stones Modified with Ortho-Phosphoric Acid for Organic Dye Removal: A Gaussian Process Regression Approach

Here, the chemical modification of Ziziphus jujuba stones (ZJS) treated with ortho-phosphoric acid (ZJS-H3PO4) is investigated to enhance its adsorption properties for organic dyes. The physicochemical properties of ZJS-H3PO4 reveal increased porosity (87.29%), slightly higher bulk density (0.034 g mL−1), and enhanced acidity (31.42 m eq g g−1) compared to untreated ZJS. XRF analysis confirms the successful incorporation of orthophosphoric acid during treatment due to a significant increase in phosphorus content. The maximum adsorption capacity of methylene blue on ZJS-H3PO4 is found to be 179.83 mg g−1, demonstrating its efficacy as a potential adsorbent for organic dyes. These findings suggest that modifying ZJS with orthophosphoric acid could be a promising strategy to enhance its adsorption performance in various environmental applications. Furthermore, Gaussian process regression (GPR) is employed to model MB adsorption by ZJS-H3PO4. Optimization of the GPR model involves evaluating different kernel functions and meticulously adjusting parameters to maximize its ability to capture complex relationships in the data. The obtained GPR model demonstrates remarkable performance with high correlation coefficients (R) and low root mean square errors (RMSEs) across all study phases. Model validation is performed through residual analysis, confirming its effectiveness and accuracy in predicting MB adsorption. Finally, a user-friendly interface is developed to facilitate the usage of the GPR model in future applications, representing a significant advancement in environmental process modeling and ecosystem management.

Retardation mechanism of phosphogypsum in phosphogypsum-based excess-sulfate cement

The effect of phosphogypsum (PG) on the hydration and retardation mechanism of phosphogypsum-based excess-sulfate slag cement (PESC) was mainly investigated. Based on the natural characteristics of PG, such as low pH value and the presence of soluble phosphorus impurities, the content of PG passing the 4.75 mm standard sieve was used as a variable to study the retardation mechanism of PG on PESC. It can be inferred from the heat flow and cumulative heat flow that the induction period is significantly prolonged with the content of PG, which is also reflected in the increase of the setting time of PESC. In the early period of hydration, as the content of PG increases, the soluble phosphorus concentration increases, and the pH value decreases. The changes in soluble phosphorus concentration and pH value affect the microstructure and amount of hydrates. Combined with experimental results, it has been demonstrated that the delay in the hydration of PESC by PG content is mainly due to: the excessive dissolution of Ca2+ and SO42- promotes the recrystallization of dihydrate gypsum; the dissolution of soluble phosphorus reduces the pH value in the pore solution and forms precipitates of calcium phosphate and hydroxyapatite; in the initial reaction period, a large amount of ettringite and C-S-H gel precipitate to form a protective film; the decrease in pH value leads to a decrease in carbonization resistance, and CO2 in the air is more likely to attack the PESC paste, react with alkaline substances in PESC, or degrade hydrated C-S-H and ettringite. The above factors all lead to a decrease in exchangeable ions during the hydration, thereby prolonging the setting of PESC.

Graphene promotes the growth of Vigna angularis by regulating the nitrogen metabolism and photosynthesis.

Graphene has promising applications in agriculture and forestry. In the current study, six different concentrations of graphene (0mg/L, 0.01mg/L, 0.10mg/L, 1.00mg/L, 10.00mg/L, and 100.00mg/L) were used to investigate its effect on the growth and development of V. angularis plants in soil culture. The results showed that the group treated with 1.00mg/L graphene (G-1) had significantly increased plant height (19.86%), stem diameter (24.33%), and leaf area (13.69%), compared to the control group (CK). Moreover, all concentrations of graphene had positive effects on the total root length, total root surface area, and the number of root tips of V. angularis. Compared to the CK group, the G-1 group had significantly increased leaf water potential (37.89%), leaf conductivity (2.25%), and SOD, POD, and CAT activities (47.67%, 35.22%, and 199.3%, respectively). The G-1 group also showed improved leaf net photosynthetic rate, chlorophyll content, and soluble sugar content (51.28%, 24.25%, and 38.35%, respectively), compared to the CK group. Additionally, 1.00mg/L graphene led to a 23.88% increase in the podding rate and a 17.04% increase in the yield of V. angularis plants. The rhizosphere soil of V. angularis treated with 1.00mg/L graphene had a 25.14% increase in hydrolyzable nitrogen content and a 66.67% increase in available phosphorus content. RNA-seq data indicated that 1.00mg/L graphene induced the expression of photosynthesis and nitrogen transmembrane transport genes, including ATP synthase subunit b, photosystem I reaction center subunit XI, photosystem I reaction center subunit IV A, ferredoxin, and psbP-like protein 1, as well as genes for photosynthesis antenna proteins, glutamine synthetase, glutamate dehydrogenase 1, cyanate hydratase, protein fluG-like, and NRT1/PTR family, suggesting that graphene promoted the growth and development of V. angularis by enhancing the photosynthesis and nitrogen metabolism processes in V. angularis plants. Our results indicated that a suitable concentration of graphene could significantly promote the growth of V. angularis plants in soil.

Co-application of biochar and salt tolerant PGPR to improve soil quality and wheat production in a naturally saline soil

Soil salinity is a global problem that drastically reduces crop productivity. Therefore, there is a need to make saline soils productive. Plant growth promoting rhizobacteria (PGPR) and biochar have been shown to increase crop productivity and soil fertility when applied separately. However, their co-application in this regard has not been studied extensively. In this study, a biochar was co-applied with Bacillus thuringiensis or Bacillus tropicus, characterized as P-solubilizing and salt-tolerant PGPR, to wheat grown in a naturally saline soil (EC 8.12 dS m−1). Co-application of biochar with PGPR increased the number of tillers & spikes, straw yield, and 100-grain weight by 16–28.57%, 26.9–36.6%, 18–21.8%, and 34–37.9% respectively. This led to a 37% and 34% increase in grain yield in the case of co-application with B. thuringiensis and B. tropicus respectively. The higher growth and yield were thanks to better plant nutrition and mitigated salinity stress under co-application. Briefly, the co-application increased phosphorus content in grain, straw, and roots by up to 9–43%, 45–69%, and 5–21.5% respectively, which was higher than that in individual applications of biochar or any PGPR. In addition, co-application increased microbial biomass by 61–77% and soil available phosphorus by 37–53% across two PGPR. Evidently, the co-application contributed to increased P nutrition in two ways. Firstly, the biochar itself served as a source of available P. Secondly, the PGPR solubilized it more abundantly when biochar was there. As far the salinity stress, biochar, its co-application with B. thuringiensis, and with B. tropicus increased soil K+/Na+ by 36%, 72% and 44% respectively leading to 40%, 63%, and 55% higher K+/Na+ in grain, straw, and roots respectively. Overall, our results indicate that biochar and PGPR worked in tandem to substantially improve soil quality and wheat production compared to their sole applications. We conclude that co-application of salt tolerant PGPR and biochar is a more sustainable and better technology to produce wheat in a naturally saline soil compared to their sole applications.

Flood irrigation increases the release of phosphorus from aquifer sediments into groundwater

Nonpoint source pollution caused by agricultural activities has long attracted widespread attention from people in society and academia. Many studies have found that human activities not only convey exogenous pollutants into aquifers but also affect the mobilization and transport of geogenic pollutants in aquifers. Geogenic groundwater with high phosphorus concentrations has been found, but it is unclear whether the changes in hydrogeochemical conditions caused by flood irrigation in paddy fields affect the fate of phosphorus. We investigated the temporal and spatial distribution characteristics of phosphorus in groundwater under the influence of flood irrigation through laboratory experiments, proved its impact on phosphorus in groundwater, and explored the mechanisms influencing P concentrations. The results show that flood irrigation can increase the release of phosphorus in the aquifer media and greatly increase the phosphorus concentration in the groundwater of the study area, which has a negative impact on groundwater quality. The main mechanism of increase in phosphorus concentration in groundwater involves an increase in the reducibility of the aquifer via flood irrigation; as a result, iron oxides are reductively dissolved and iron-bound phosphorus is released into the groundwater. Changes in pH also result in the dissolution of calcium phosphate minerals and the release calcium-bound phosphorus. This study not only advances the theory of multielement-coupled hydrogeochemistry but also provides a reference for agricultural planning and groundwater pollution prevention and control in rice-growing areas.

Effect of phytic acid on the structure, properties and oil absorption of wheat flour

With the different amount (0%, 0.25%, 0.5%, 1%, 1.5%, 2%) of phytic acid (PA) added, the changes of structure, properties and oil absorption characteristics of wheat flour (WF) were studied. First of all, the phosphorus content in flour increased after PA treatment, which proved that the modification was successful. SEM images showed there were aggregation in the WF modified by PA (PA-WF). The surface of starch showed gradually rough, but the shape of starch particles remained relatively intact. Moreover, XRD and FTIR patterns of all samples showed no significant difference. It was proved that the degree of structural modification of flour by PA was small in the non-gelatinizing system, and it mainly occurred in the non-crystalline region. In terms of properties, the thermal stability and hydrophilicity of PA-WF were improved because the phosphate groups of PA reacted with the hydroxyl groups on the starch to form more stable covalent bonds instead of the hydrogen bonds, and the phosphate groups were hydrophilic. Not only that, the peak viscosity of PA-WF-1.5% was higher than that of the control group, and the other PA-WF were the opposite. With the increase of phosphorus content, the peak viscosity were lower than that of the control group, suggesting that the system mainly consisted of crosslinked starch rather than esterified starch. In terms of oil absorption characteristics, the total oil absorption and surface oil distribution of PA-WF were decreased after frying, which proved that using PA to modify WF was beneficial to reduce oil absorption.

The Strength and Fire Properties of Paper Sheets Made of Phosphorylated Cellulose Fibers.

Phosphorylated cellulose can be an intrinsic flame retardant and a promising alternative for halogenated fire inhibitors. In this study, the mixture of di-ammonium hydrogen phosphate (DAP) and urea (U), containing phosphate and nitrogen groups, was applied to attain fire inhibitor properties. Functional groups of cellulose were grafted with phosphorous by keeping the constant molar ratio of 1/1.2/4.9 between anhydroglucose units of cellulose/DAP/U in different concentrations of bleached kraft pulp. Phosphorus concentrations were determined using the ICP hrOES method, and paper sheets were made using the Rapid Köthen apparatus. The tensile strength of phosphorylated cellulose increased twice compared with unmodified cellulose when the phosphorous concentration increased to 10,000 g/kg. An increase in the tensile index comes from the higher freeness of pulp and cross-linking of the phosphorous group between cellulose fibers. Remarkable fire retardancy effects were achieved in cellulose concentrations above 5 wt%. The raised phosphorous concentration above 10,000 g/kg due to the phosphorylation process caused the formation of a char layer on a cellulose surface and the nonflammable gas emission. That effect was indirectly confirmed by reducing the combustion temperature and HRR by 50 and 45%, respectively. Due to increasing phosphorus concentration in cellulose sheets, cellulose's fire and strength properties increased significantly.

Adubação orgânica e mineral determina o desempenho agronômico de cultivares de girassol e atributos químicos do solo

ABSTRACT This study aimed to verify the effect of the application of filter cake, via soil and in association with mineral fertilization, on sunflower cultivars (Helianthus annuus L.) and the chemical properties of the soil. The experimental design used was randomized blocks in a 3 × 2 factorial scheme with six replicates, totaling 36 experimental units. Three sunflower cultivars (Sany 66, Nusol 4140, and Nusol 4170) and two fertilization strategies (mineral fertilization with and without filter cake) were used. Resorting to the filter cake increased the oil concentration in Sany 66. Mineral fertilization did not significantly affect achene production, with mean values being 2561.58 kg ha-1. However, including filter cake resulted in a 21% increase in phosphorus (P) content in the 0-0.20 m soil layer in sunflower crops of the Nusol 4140 variety. Therefore, fertilization with filter cake, in combination with chemical fertilizers or alone, can be an effective strategy to increase soil P content and oil concentration in sunflower cultivation.

The role of bioturbation triggered by benthic macroinvertebrates in the effectiveness of the Floc & Lock technique in mitigating eutrophication

Anthropogenic activities have led to excessive loading of phosphorus and nitrogen into water bodies, leading to eutrophication and promoting the growth of cyanobacteria, posing a threat to the health of humans and aquatic animals. Techniques such as Floc & Lock have been developed to mitigate eutrophication by reducing phosphorus concentrations in water and preventing algal blooms. However, little attention has been given to the impact of phosphorus resuspension by sediment-associated organisms such as benthic macroinvertebrates, on the effectiveness of this technique. Here, we experimentally evaluated whether the presence of snails Melanoides tuberculata (Müller, 1774) and larvae of Chironomus sancticaroli (Strixino and Strixino, 1981) affects the efficiency of the Floc & Lock technique. Snails and chironomid larvae are benthic macroinvertebrates commonly found in high abundance in eutrophic reservoirs. Specifically, we tested the hypotheses that (i) the presence of benthic macroinvertebrates reduces the efficiency of coagulants and clays in removing phosphorus and algal biomass from the water column, and (ii) this effect is species-dependent, as some organisms such as the snails, revolve the substrate and resuspend sedimented particles, while other ones, such as chironomid larvae, aid in the removal of phosphorus from the water column by depositing them in the sediment. Our findings revealed that the impact of benthic macroinvertebrates on the effectiveness of the Floc & Lock technique is species-dependent. Chironomid larvae positively influenced the efficiency of the technique by aiding in the removal of total phosphorus, soluble reactive phosphorus, and algal biomass from the water column, depositing them in the sediment. In contrast, the presence of snails had the opposite effect, resulting in increased phosphorus concentration and algal biomass in the water. Surprisingly, the snails consumed the flocs formed by the coagulant and clay within a short time interval of 72 h, raising concerns due to the presence of toxic cyanobacterial biomass in these flocs. Our study emphasizes the importance of considering benthic macroinvertebrates and their impact on the effectiveness of eutrophication management techniques.

Wetland productivity determines trade-off between biodiversity support and greenhouse gas production.

Establishing wetlands for nutrient capture and biodiversity support may introduce trade-offs between environmentally beneficial functions and detrimental greenhouse gas emissions. Investigating the interaction of nutrient capture, primary production, greenhouse gas production and biodiversity support is imperative to understanding the overall function of wetlands and determining possible beneficial synergistic effects and trade-offs. Here, we present temporally replicated data from 17 wetlands in hemi-boreal Sweden. We explored the relationship between nutrient load, primary producing algae, production of methane and nitrous oxide, and emergence rates of chironomids to determine what factors affected each and how they related to each other. Chironomid emergence rates correlated positively with methane production and negatively with nitrous oxide production, where water temperature was the main driving factor. Increasing nutrient loads reduced methanogenesis through elevated nitrogen concentrations, while simultaneously enhancing nitrous oxide production. Nutrient loads only indirectly increased chironomid emergence rates through increased chlorophyll-a concentration, via increased phosphorus concentrations, with certain taxa and food preference functional groups benefitting from increased chlorophyll-a concentrations. However, water temperature seemed to be the main driving factor for chironomid emergence rates, community composition and diversity, as well as for greenhouse gas production. These findings increase our understanding of the governing relationships between biodiversity support and greenhouse gas production, and should inform future management when constructing wetlands.

Arbuscular Mycorrhizal Fungi Restored the Saline-Alkali Soil and Promoted the Growth of Peanut Roots.

Peanut (Arachis hypogaea L.) is an important oil and cash crop. An efficient utilization of saline-alkali soil resources, the development of peanut planting in saline-alkali soil, and obtaining high and stable yield have become urgent needs to ensure peanut production. Arbuscular mycorrhizal fungi (AMF) have been reported to develop the potential productivity of host plants and improve their salt resistance and tolerance. However, there is still limited research on promoting the growth and morphology of peanut roots. Therefore, in this study, seeds of salt-tolerant peanut variety "HY 25" were coated with commercial AMF inoculant before being planted in saline-alkali and normal soils to investigate the effects of AMF on peanut root growth and rhizosphere soil. The results showed that root morphological characteristics were significantly increased by the use of AMF at the podding stage in saline-alkali soil and from the flowering and pegging stage to the maturity stage in normal soil. Of note, the total root volume of peanut inoculated with AMF significantly increased by 31.57% during the podding stage in saline-alkali soil. Meanwhile, AMF significantly increased the phosphatase and invertase activities in the peanut rhizosphere of saline-alkali soil from the flowering stage to maturity stage and soil CAT activity at the maturity stage (41.16~48.82%). In normal soil, soil phosphatase and urease activities were enhanced by AMF at the flowering stage and the podding stage, respectively. AMF also increased the contents of soil organic matter, available phosphorus, and hydrolysable nitrogen, but decreased soil EC in saline-alkali soil. In addition to the significant increase in soil available phosphorus content, AMF had no significant effect on the physical and chemical properties of the soil and other soil nutrients in normal soil. AMF significantly increased pod biomass and yield in saline-alkali soil and normal soil, and improved their agronomic characteristics. In conclusion, peanut seeds coated with AMF improved the root morphological characteristics of peanuts and improved the physical and chemical properties in peanut rhizosphere, especially in saline-alkali soil. The process of rhizosphere soil nutrient transformation was also enhanced. Finally, AMF improved plant agronomic traits to increase the pod yield (16.5~21.9%). This study provides the theoretical basis and technical support for the application of AMF in peanut production in saline-alkali soil.

Phosphate in Aqueous Solution Adsorbs on Limestone Surfaces and Promotes Dissolution

The use of large quantities of phosphorus-containing fertilizers has resulted in an increase in phosphorus content in the groundwater system, and phosphorus can be adsorbed on the surface of carbonate rocks, affecting their dissolution process and thus carbon sequestration and sink enhancement in carbonate rocks. Therefore, in this study, limestone was exposed to 2 mg/L and 100 mg/L phosphate solutions for 12 d through static batch adsorption experiments. The hydrochemical results showed that in 100 mg/L phosphate solution, a substitution reaction occurred to produce CaHPO4 precipitate, while the concentration of each ion in 2 mg/L phosphate solution was relatively stable and in dynamic equilibrium; combined with XRD and XPS analyses, the main mechanism of phosphate adsorption may be chemical precipitation, which is preferentially adsorbed to Ca sites on carbonate rocks, and the surface deposits are mainly CaHPO4 and a small amount of Mg2PO4(OH). The FTIR spectra were obtained in the range of 1040 cm−1–1103 cm−1 for observed phosphate vibrations, and the υ3 (asymmetric stretching) mode was more significant in the experimental group with a higher phosphate concentration. Raman spectra located near 149 cm−1 and 275 cm−1 involved Ca2+ or Mg2+ relative translations and vibrations, corroborating the FTIR spectroscopic results; a combination of XRD, XPS, FTIR, and Raman spectra confirmed that phosphate adsorption on limestone may be due to the interaction of electrostatic, chemical precipitation, and ligand exchange mechanisms. In addition, the SEM-EDS results showed that, with the combined effect of the water–rock chemical reaction and physical adsorption, metal–phosphorus phase precipitation was formed on the limestone surface, which promoted the dissolution of limestone and may have an unfavorable effect on the carbon sequestration and sinking of carbonate rocks.

Addressing Phosphorus Waste in Open Flow Freshwater Fish Farms: Challenges and Solutions

Legislation and interest exists to protect and restore freshwater and marine ecosystems from the environmental impact of aquaculture. However, aquaculture-induced eutrophication remains a major environmental concern. Water soluble phosphorus, uneaten feed, feces, and metabolic waste from farmed fish increase phosphorus concentrations in adjacent waters. In open freshwater fish farms, in particular, the effects can be more immediate, as excess phosphorus is introduced directly into ecosystems. Several intestinal enzymes, transporters, and regulating factors have been implicated in farmed fish dietary phosphorus retention. For example, alkaline phosphatase and other transporters aid in the absorption of phosphorus in the anterior intestine, while pH, calcium, and vitamin D influence these enzymes and transporters. This process may also be influenced by intestinal morphology and the gut microbiome. To reduce phosphorus pollution from open flow fish farms, a thorough understanding of the processes that affect nutrient retention and absorption, as well as the impact of dietary factors, anti-nutritional substances, and intestinal morphology, is required. Aquaculture can be made more sustainable by reducing phosphorus release. This can be achieved by optimizing feed composition, adding functional feed ingredients, managing gut health, and treating effluent aquaculture waters with bioremediation and absorbing materials. Anti-nutritional factors can be mitigated through processing and through the use of functional feed additives. Addressing these issues will reduce aquaculture’s environmental impact, ensuring aquatic ecosystem health and global food security. In addition, treating effluent aquaculture waters with bioremediation and absorbing materials can remove phosphorus from the water, preventing it from entering the environment. This can further reduce the environmental impact of aquaculture and help to ensure the sustainability of this sector.

Removal of Phosphate by Adsorption with 2-Phenylimidazole-Modified Porous ZIF-8: Powder and Chitosan Spheres.

Due to rapid socioeconomic development, increased phosphorus concentrations can cause eutrophication of water bodies, with devastating effects on environmental sustainability and aquatic ecosystems. In this study, ZIF-8-PhIm was prepared for phosphorus removal using 2-phenylimidazole via the solvent-assisted ligand exchange (SALE) method. The structure and composition of ZIF-8-PhIm were characterized by various methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analysis. Compared to the ZIF-8 material, it exhibited a multistage pore structure with larger pore capacity and pore size, increased hydrophilicity, exposure of more adsorption sites, and also stronger electrostatic interaction. Under optimized conditions (T = 298 K, C0 = 150 mg/L, dose = 0.2 g/L), the adsorption capacity of ZIF-8-PhIm reached 162.93 mg/g, which was greater than that of the ZIF-8 material (92.07 mg/g). The Langmuir isotherm and pseudo-second-order kinetic models were suitable for describing the phosphate adsorption of ZIF-8-PhIm. The main effects of ZIF-8-PhIm on phosphate adsorption were Zn-O-P bonding and electrostatic interactions. It also had good regeneration properties. The ZIF-8-PhIm/CS spheres were prepared using chitosan (CS) as the cross-linking agent. The results of dynamic adsorption experiments on the spheres showed a saturation capacity of 85.69 mg/g and a half-penetration time of 514.15 min at 318 K according to the fitted results.

Gel properties of the gum from Chinese quince (Chaenomeles sinensis) seeds

The effect of pH and different types and concentrations of salt ions on the gel properties of gum extracted from Chinese quince seeds (CQSG) were investigated by analysing the texture, flow behaviour, water-holding capacity (WHC), zeta potential, and thermal and morphological properties of the gels formed by the gum. Results indicated that the pH and different types and concentrations of ions significantly affected the properties and microstructure of the CQSG gels. However, the various conditions had no obvious effects on the gelling and melting temperatures of the CQSG gels. The effects of the tested salt ions on the WHC of the CQSG gels exhibited different patterns. The zeta potential value increased continuously from -45 to -53 mV with increasing phosphorus concentration, while the presence of CaCl2 caused a continuous decrease in the zeta potential from -35 mV (0.2 wt%) to -22 mV (2 wt%). The present work provides fundamental data for designing novel gelling agents based on gum from Chinese quince seeds for use in processed food.

Feasibility of laser-induced breakdown spectroscopy to elucidate elemental changes in human tooth ankylosis

Tooth ankylosis is a pathological condition associated with the loss of physiological tooth mobility when the firm fusion between the alveolar bone and the tooth root occurs. Causes of dental ankylosis are uncertain, so the analysis of elemental distribution in ankylotic and surrounding tissues could provide additional information about its initiation and progression. Here, we used Laser-Induced Breakdown Spectroscopy (LIBS) to determine differences in the mineral composition among ankylotic tissue, bone, and dental tissue taking advantage of its high throughput and multi-elemental capability. Elemental imaging was performed with a spatial resolution of 30 μm to evaluate the distribution of carbon, calcium, magnesium, phosphorus, and strontium in human tooth. To further verify the difference in the mineral composition of ankylotic tissue, the semi-quantitative content of these elements was compared within the region of interest. We revealed a significant increase in calcium, magnesium, and phosphorus contents in the ankylotic tissues. However, the contents of magnesium and phosphorus were not significantly changed. This finding suggests a mineral disbalance only of just certain elements in the tooth-bone interface area during the spread of ankylosis associated with an intense calcification of connective tissue. This paper brings a feasibility study and shows the way of LIBS data interpretation. We propose that the LIBS analysis on a micro-scale can contribute to the understanding of ankylotic tissue composition and can distinguish even small differences of carbon, calcium, magnesium, phosphorus, and strontium contents on the tooth-bone boundary during the initiation of ankylosis. Therefore, it represents a new useful tool for their future, more extensive analyses.