Increase In Phosphate Concentration Research Articles

Assessing Present and Future Ecological Status of Ria de Aveiro: A Modeling Study

Coastal lagoons hold significant ecological value due to their rich biodiversity and essential roles in supporting ecosystems. However, they are increasingly threatened by accelerated climate change, and it is crucial to assess these environments’ ecological status for present and future conditions resulting from the impacts of climate change. In this context, the present work aims to evaluate the present and future ecological status of Ria de Aveiro through the application of the numerical model Delft3D. The model was validated, and the results demonstrate that it effectively captures the main characteristics of the lagoon dynamics, although achieving accurate water quality representation poses challenges due to interdependencies in solutions and the inherent complexity of associated processes. The model was explored to characterize the environmental factors of the lagoon and evaluate its ecological status through the computation of several indexes. According to the model results, the main environmental factors present seasonal variations consistent with temperate climates. Regarding the ecological status of Ria de Aveiro, the central channels of the lagoon mostly hold a Good/Moderate status, while regions near river inflows tend to exhibit Moderate to Poor conditions. In future conditions, water quality is expected to improve in winter and autumn due to reductions in river-borne pollutants resulting from the projected decrease in river flow. For spring and summer, a decline in water quality is projected mainly due to the increase in phosphate concentrations in the lagoon. This study provides valuable insights into the ecological dynamics of coastal lagoons under changing climatic conditions, contributing to improved management and mitigation strategies. The findings can guide future conservation efforts and help mitigate the adverse effects of climate change on these vital ecosystems.

Higher phosphate concentrations as in aqueous humor of diabetic patients increase intraocular lens calcification

BackgroundClinical evidence suggests an association between phosphate concentrations in aqueous humor and the risk of intraocular lens (IOL) calcification. To test this hypothesis the influence of different phosphate concentrations on IOL calcification was evaluated in an in vitro electrophoresis model.Methods20 IOLs of two hydrophilic IOL models (CT Spheris 204, Zeiss; Lentis L-313, Oculentis) and one hydrophobic control IOL model (Clareon CNA0T0, Alcon) were exposed to physiologic and elevated phosphate concentrations, similar to diabetic aqueous humor. IOL calcification was analyzed by alizarin red staining, von Kossa staining, scanning electron microscopy, energy dispersive x-ray spectroscopy and transmission electron microscopy with electron diffraction.ResultsHigher phosphate concentrations were associated with IOL calcification. Analyses of IOL surfaces and cross-sections documented calcification in no CT Spheris and 4 Lentis IOLs following exposure to 10 mM Na2HPO4, compared with 7 and 11 positive analyses following exposure to 14 mM Na2HPO4, respectively. Furthermore, a clear association between IOL calcification and the duration of electrophoresis was demonstrated, confirming increased phosphate concentrations and duration of exposure as risk factors of IOL calcification.ConclusionsFindings suggest that higher phosphate concentrations in aqueous humor, as seen in diabetic patients, contribute to an increased IOL calcification risk, potentially explaining clinical observations showing an increased risk of IOL calcification in patients with diabetes.

Hydrothermal mineral replacement in the apatite-rhabdophane-monazite system: Experiments, reaction mechanisms and geological implications

Apatite, rhabdophane and monazite are actinide- and rare-earth element (REE)-bearing phosphate minerals with diverse geoscientific applications. However, their mineral-fluid reaction mechanisms below 200 °C are understudied. Insufficient understanding as to how these minerals behave during hydrothermal alteration impedes useful interpretations of REE-U-Th mobilisation in regolith profiles, diagenetic environments and low-temperature hydrothermal systems. This work experimentally investigates the replacement of apatite by rhabdophane in a Ce-doped acidic fluid at 30 °C, and of rhabdophane by monazite in REE-barren acidic fluids at 180 °C. Rhabdophane replaced apatite via the coupled dissolution-precipitation mechanism, forming nanoscale prisms clustered into spherulitic aggregates. Interstitial voids that formed between rhabdophane and apatite indicate how rhabdophane precipitation was the rate-limiting step. Void widths varied in response to apatite's anisotropic dissolution; rapid dissolution parallel to the c-axis formed the widest voids (50–125 μm) and thickest rhabdophane layers (20–50 μm), while slow dissolution perpendicular to the c-axis formed narrower voids (< 1 μm) and thinner layers (< 5 μm). At 180 °C, monazite also replaced rhabdophane via the dissolution-precipitation mechanism. Replacement rates increased with increasing phosphate concentrations, implying that monazite precipitation was the rate-limiting step. However, microscale rhabdophane aggregates were pseudomorphically preserved. This is attributed to the shared orientation of rhabdophane prisms (not pseudomorphically preserved) and their intergranular boundaries which, as microreactors, guided monazite precipitation. Both replacement reactions were accompanied by a loss of U to solution, which is attributed to the stabilisation of uranyl-phosphate complexes under acidic conditions. Results indicate that: 1) anisotropic dissolution can govern the extent of rate coupling between dissolution and precipitation during mineral replacement; 2) the pseudomorphic replacement of mineral aggregates can occur when precipitation is the rate-limiting step; 3) rhabdophane is a feasible (and perhaps necessary) metastable precursor to authigenic monazite precipitation in low temperature hydrothermal systems; 4) highly porous aggregates of both rhabdophane and monazite generate insufficient EPMA totals, such that they cannot be differentiated by EPMA alone, and; 5) phosphate complexes can mobilise U under certain hydrothermal conditions, with implications for geochronology, nuclear waste management and the formation of REE deposits.

Antifungal activity of Neowestiellopsis persica against Rhizoctonia solani in root and crown of Faba bean cultivated under modified BG-110 medium composition

Rhizoctonia solani, a fungal pathogen, affects the quality and yield of Faba bean crops and hinders plant export. Chemical fungicides effectively control fungal pathogens, but their long-term use harms the environment, soil properties, and human health. Cyanobacteria, a promising source of natural bioactive compounds, have shown efficacy against the fungal colony growth of various plant pathogens, highlighting the need for sustainable practices. As a result, this study examined the biological control of the Rhizoctonia solani disease that affects the Faba bean's root and crown. Disease assessments were then done in five groups: (1) healthy control; (2) control infected with Rhizoctonia solani and not treated with cyanobacterial extract; (3) plant infected with Rhizoctonia solani and treated with cyanobacterial extract suspension of 0.02, (4) 0.04, and (5) 0.08 g/L phosphate during 20 and 34 days. The results of the antioxidant activity by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay showed that with increasing phosphate concentration, the activity increased significantly. The results of enzymatic activity indicated that time did not significantly impact the enzymatic activity of glutathione peroxidase (GPx), catalase (CAT), and guaiacol peroxidase (GPX), with the highest and lowest activity being related to codes 2 and control, respectively. However, time had a significant effect on superoxidase dismutase (SOD) activity, with the highest activity reported on day 35. Moreover, the results showed that increasing the concentration of the extract significantly decreased cell viability in hepatoblastoma (HepG-2) cell lines. The cyanobacterial extract treatment caused over 66 % damage to plants infected with Rhizoctonia solani. The overall results indicated that Neowestiellopsis persica, grown under higher phosphate concentrations, can be used as an effective antifungal biocontrol against Rhizoctonia solani in Faba bean roots and crowns.

#1288 Bioinformatic analysis of phosphate transporters in peritoneal cells and tissues and phosphate transport kinetics in vitro

Abstract Background and Aims Hyperphosphatemia is frequent in peritoneal dialysis (PD) patients due to limited dialytic clearance, and significantly increases cardiovascular risk. Molecular mechanisms of phosphate removal across the peritoneal membrane remain unclear, PD specific in vitro models for phosphate transport and modulator studies are not established. Method Phosphate transporter expression was assessed by RNAseq in mesothelial cells (HPMC, MeT5A) and human venous and microvascular endothelial cells (HUVEC, HCMEC). Transcriptome profiles of microdissected omental arterioles from 10 children with normal kidney function (NKF), 15 with chronic kidney disease (CKD5), and 10 children on PD were analyzed for phosphate transporter expression. Specific phosphate transporter localization and abundance in parietal peritoneum membranes and in the cell lines were assessed by immunostaining. In Transwell system, a phosphate transport model across polarized monolayers was established. Cell viability and integrity were verified by MTT assay and transepithelial resistance measurement (TER). Results Out of nine identified phosphate transporters, PiT1 (SLC20A1) and PiT2 (SLC20A2) exhibited high expression in all four cell lines, while SLC34A2 was specific in HPMC and SLC34A3 in MeT5A. In human arterioles, four phosphate transporters, SLC34A1, PiT1, PiT2, and SLC17A1, were detected. Arteriolar PiT1 was two-fold more abundant in PD patients treated with low glucose degradation product (GDP) fluids compared to those with CKD5 and NKF. In parietal peritoneal membranes, PiT1 was abundant in mesothelial and endothelial cells, with no difference between children with NKF, CKD5 and low GDP PD treatment. Concentration and time dependent phosphate kinetics across polarized mesothelial cells were studied in Transwells. Upon increased phosphate concentration in medium (1 mM and 2 mM vs. 0.1 mM), cells didn´t show signs of impaired viability, reduced TER or junction dysregulation (ZO-1 abundance) for up to 12 h. Independent of the added phosphate concentration, 60% of expected equilibrium was achieved after 12 h. Addition of PFA (SLC20/34 sodium-phosphate cotransporter inhibitor) alone or in combination with Tenapanor (an NHE3 blocker inhibiting paracellular phosphate transport) reduced phosphate transport across mesothelial cells by 10% and 20%, respectively. Conclusion We describe phosphate transporter expression and localization in peritoneal cells, in arterioles and parietal peritoneal tissues, and the impact of CKD5 and PD. The Transwell system allowed for quantification of phosphate transport across cell barriers and demonstrated the role of peritoneal sodium-phosphate cotransporter and of the paracellular route for phosphate transport across the mesothelial cell barrier. Further, yet unknown phosphate transport mechanisms should be active.

Influence of operation sequences on phosphorus recovery by polyphosphate-accumulating organisms biofilm: Performance, kinetics and metabolic response

Two biofilm sequencing batch reactors (BSBRs) were conducted under alternating aerobic/anaerobic (Ae/An) sequence and alternating anaerobic/aerobic (An/Ae) sequence to investigate the effects of operation sequences on phosphorus removal and recovery performance. The Ae/An BSBR had advantages in phosphate enrichment, phosphorus concentration of enrichment solution can reach 99.08 mg/L. While An/Ae BSBR exhibited a higher kinetic rate for phosphate uptake and release up to 0.48 mmol/gVSS. In An/Ae BSBR, the remarkable increase of phosphate concentration in aerobic stage put a great strain on the phosphate uptake of biofilms that led to an increase of phosphorus accumulation in the biofilm (Pbiofilm). However, the poly-P proportion in TPbiofilm decreased which triggered the metabolisim of polyphosphate accumulating organisms (PAOs) shifting from polyphosphate accumulating metabolism (PAM) to glycogen accumulating metabolism (GAM) and suppressed the phosphorus enrichment performance of the An/Ae BSBR. The phosphate uptake rate (PUR) of biofilms was in alignment with the bulk phosphate concentration. PAOs were dominated by Rhodoplanes and Saprospiraceae in the Ae/An BSBR, whereas Thiothrix was predominant in the An/Ae BSBR. Notably, the Candidatus Competibacter, considered as a denitrifying glycogen accumulating organisms (DGAOs), showed a dominant proportion in the microbial community of both BSBRs. The higher expression of actP in the An/Ae system indicated a greater capacity for the uptake of acetate, while the Ae/An system was is more adept for degrading acetate represented by the higher relative abundance of ackA, pta and acsA genes The high phosphorus loading in the An/Ae system suppressed the ppk expression but enhanced the ppx expression.

Biogeochemical dynamics in a marine storm demonstrates differences between natural and anthropogenic impacts

This study explores the impact of a wind storm on sediment resuspension and marine biogeochemical dynamics. Additionally, the storm took place during an expedition researching bottom trawling, enabling the direct comparison of certain natural and fisheries-related disturbances. The storm was initiated by a decline in atmospheric pressure and a 2 h period of gale force winds, which was followed by over 40 h of elevated bottom currents. Storm induced turbidity, potentially a cumulative post-fishing impact, was remarkably higher compared to what was observed in a recent trawling event. Storm-induced mixing and movement of water masses led to decreased silicate and increased phosphate concentrations in the water column, accompanied by lower salinity and higher fluorescence. The erosion depth of the seabed averaged around 0.3 cm during the peak turbidity period. Trawl-induced erosion in the area has been measured at over twice that depth, and has been linked to intermittent reductions in near-bed oxygen levels. In contrast, storm-induced turbidity coincided with increased oxygen due to wave mixing, suggesting inherent differences in how trawling and storms can oxidize reduced substances. These findings suggest that storms have a greater regional impact, whereas the local impacts of bottom trawling on biogeochemistry can be more significant.

Citizen scientists filling knowledge gaps of phosphate pollution dynamics in rural areas

In situ monitoring is fundamental to manage eutrophication in rivers and streams. However, in recent decades, the frequency and spatial coverage of regulatory monitoring have often been reduced due to funding and infrastructure limitations. This reduction has made it impossible to provide adequate coverage for most water bodies. In this study, trained citizen scientists filled spatial and temporal gaps in agency monitoring across a major catchment in rural England. By integrating data from citizen scientists, regulatory agencies, and the local water company, it was possible to demonstrate the opportunities for hypothesis-based citizen scientist monitoring to identify continuous and event-driven sources of phosphate pollution. Local citizen scientists effectively covered important spatial gaps, investigating river conditions both upstream and downstream of suspected pollution point sources, improving the identification of their temporal dynamics. When combined with long-term monitoring data from regulatory agencies, it became possible to identify areas within the catchment that exhibited increased phosphate concentrations during periods of low river discharge (summer). Inter-annual trends and anomaly detection suggested that continuous pollution sources dominated over event-driven sources in many sub-basins, allowing for the prioritisation of mitigation actions. This study highlights the opportunity for citizen scientists to fill gaps in regulatory monitoring efforts and contribute to the improved management of eutrophication in rural catchments.

Growth and phosphate uptake of microalgae under different phosphate conditions

Microalgae could utilize the nutrients in the environment and therefore are widely used in wastewater treatment. The variety and complexity of phosphates in the water column and different types of wastewater can affect the growth of microalgae, which further affects the treatment efficiency of phosphorus- containing wastewater. In this study, phosphate uptake and microalgal growth were investigated under different phosphate conditions. The results showed that the increase of phosphate concentration could promote the growth of microalgae. Phosphate species affected the phosphate uptake and transformation process. Orthophosphate and polyphosphate were first adsorbed on the surface of microalgae and then transported inside the cell. Polyphosphates produce desorption in the early stages of uptake. The adsorbed polyphosphates were released back into the culture medium and were taken up and utilized again in the later stages of incubation. Polyphosphates were taken up and utilized by microalgae for a longer period of time than orthophosphates. It was also found that orthophosphate was more readily utilized by microalgae compared to polyphosphate. An increase in phosphate concentration promotes the growth of microalgae.

Effect of electrolyte composition on the formation of PEO coatings on AA2024 aluminium alloy

Since the electrolyte composition plays a crucial role in the plasma electrolytic oxidation (PEO) coating formation process, a systematic and in-depth study was proposed to identify an electrolyte composition for fast PEO coating growth on AA2024 alloy. Different concentration ratios of mixed alkaline electrolytes (hydroxide, silicate and phosphate) were investigated. PEO process was conducted at low constant current density of 50 mA/cm2, which is intended for lowering the energy consumption. Results demonstrated that the breakdown voltage of PEO coatings is directly proportional to the logarithm of electrolyte resistivity. The coating growth mechanism showed two main directions. The thickening of the coating mainly depends on the rapid deposition of electrolyte compounds in Si-based electrolyte, and the coating growth occurs mainly towards the electrolyte/coating interface. Contrary, in OH-, and P-based electrolytes, the inward coating growth was dominating mainly by substrate oxidation. A variety of phases as a function of different electrolyte compositions and final voltages were observed. With high final voltages (over 470 V) for coatings produced in mixed electrolytes with low concentrations of hydroxide, silicate or phosphate (2 and 6 g/L), γ-Al2O3 crystalline phase predominates in the PEO layer composition. However, only a low efficiency of coating growth can be reached. In the electrolytes with high silicate concentrations accompanied by an increase of phosphate concentration, the final voltage is around 455 V and the coating composition is dominated by an amorphous phase in combination with crystalline mullite and γ-Al2O3. High silicate-phosphate contents (18–24 g/L) in mixed electrolytes with low final voltages of about 360 V results in a fully amorphous PEO layer and significantly increases coating thickness. A combination of low content of hydroxide, high silicate with increasing content of phosphate in mixed electrolyte increases the coating thickness, and improves the density and uniformity of the overall PEO layers.

Transduction of Amine-Phosphate Supramolecular Interactions and Biosensing of Acetylcholine through PEDOT-Polyamine Organic Electrochemical Transistors.

Organic electrochemical transistors (OECTs) are important devices for the development of flexible and wearable sensors due to their flexibility, low power consumption, sensitivity, selectivity, ease of fabrication, and compatibility with other flexible materials. These features enable the creation of comfortable, versatile, and efficient portable devices that can monitor and detect a wide range of parameters for various applications. Herein, we present OECTs based on PEDOT-polyamine thin films for the selective monitoring of phosphate-containing compounds. Our findings reveal that supramolecular single phosphate-amino interaction induces higher changes in the OECT response compared to ATP-amino interactions, even at submillimolar concentrations. The steric character of binding anions plays a crucial role in OECT sensing, resulting in a smaller shift in maximum transconductance voltage and threshold voltage for bulkier binding species. The OECT response reflects not only the polymer/solution interface but also events within the conducting polymer film, where ion transport and concentration are affected by the ion size. Additionally, the investigation of enzyme immobilization reveals the influence of phosphate species on the assembly behavior of acetylcholinesterase (AchE) on PEDOT-PAH OECTs, with increasing phosphate concentrations leading to reduced enzyme anchoring. These findings contribute to the understanding of the mechanisms of OECT sensing and highlight the importance of careful design and optimization of the biosensor interface construction for diverse sensing applications.

Research of phosphate removal from water on reverse osmotic filters

Eutrophication of natural water bodies caused by an excess of biogenic substances is one of the global environmental problems of modern times. Usually, phosphorus is a limiting biogenic element, the concentration of which determines the intensity of eutrophication processes in water bodies. Therefore, it is important to develop methods aimed at preventing excessive amounts of phosphates from entering the environment. To remove phosphates from water, typically used biological degradation technologies, which usually proceed very slowly and depend on the conditions under which the process takes place. Also, Biogenic elements can be removed by using ion exchange, reverse osmosis, and chemical methods. However, the disposal of concentrated solutions becomes an issue with these methods. Baromembrane purification methods, particularly reverse osmosis, are becoming increasingly important in the field of water treatment and purification and are essential in creating efficient and low-waste complex technologies for water purification from biogenic compounds. The study investigated the processes of removing orthophosphates from distilled and artesian water using a low-pressure reverse osmosis membrane Filmtec TW30-1812-50. The dependence of membrane productivity and selectivity on the concentration of phosphates and the degree of permeate rejection was determined. Was found that residual concentrations of phosphates in the permeate increase with the increase in the degree of permeate rejection. The lowest residual concentrations of phosphates were observed at the initial concentration of up to 10 mg/dm3. The highest residual phosphate concentrations were observed at initial concentrations above 900 mg/dm3. At the same time, the membrane productivity constantly decreased with increasing feed concentration and degree of permeate recovery due to the increased osmotic pressure on the membrane. The selectivity of the membrane was highest at an initial concentration of up to 10 mg/dm3 and slightly decreased at a rejection rate of 20-50% for initial phosphate concentrations of 100-900 mg/dm3. At the maximum degree of permeate rejection (90%), the selectivity of the membrane reached 97-99 % and decreased with an increase in phosphate concentrations, which is due to a change in the pH of the medium, hydrolysis of phosphates, hydration of ions, and concentration polarization. The membrane selectivity for phosphates in solutions in artesian water was slightly lower (95-99 %), which was due to the competing influence of chlorides, sulfates, and bicarbonates, as well as a decrease in the pH of the solution to 7.52-7.67, which promotes the hydrolysis of o-phosphates.

Overexpression of ClWRKY48 from Cunninghamia lanceolata improves Arabidopsis phosphate uptake.

Our findings suggested that ClWRKY48 promoted the expression level of Arabidopsis phosphate transporter genes, enhanced phosphate uptake, and delayed the transition from the vegetative stage to the reproductive phase in Arabidopsis. Phosphorus (P) is an essential mineral for plants that influences their growth and development. ClWRKY48, one of the most highly expressed genes in the leaf, was identified by RT-PCR from Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] (C. lanceolata). Furthermore, when treating C. lanceolata with increasing phosphate (Pi) concentration, the expression level of ClWRKY48 rose in leaves, the trends followed the increasing phosphate concentration treatment. ClWRKY48 is a transcription factor in C. lanceolata, according to the results of a yeast one hybridization experiment. Based on subcellular localization studies, ClWRKY48 is a nuclear-localized protein. Under Pi deficiency conditions, the phosphorus concentration of ClWRKY48 overexpressing Arabidopsis increased by 43.2-51.1% compared to the wild-type.Moreover, under Pi limiting conditions, the phosphate transporter genes AtPHT1;1 (Arabidopsis Phosphate transporter 1;1), AtPHT1;4, and AtPHO1 (Arabidopsis PHOSPHATE 1) were expressed 2.1-2.5, 2.2-2.7, and 6.7-7.3-fold greater than the wild-type in ClWRKY48 transgenic Arabidopsis, respectively. Under Pi-sufficient conditions, the phosphorus concentration and phosphate transporter genes of ClWRKY48 overexpression in Arabidopsis are not significantly different from the wild type. These findings indicated that ClWRKY48 increased phosphate absorption in transgenic Arabidopsis. Furthermore, compared to the wild type, the ClWRKY48 transgenic Arabidopsis not only had a delayed flowering time characteristic but also had lower expression of flowering-related genes AtFT (FLOWERING LOCUS T), AtFUL (FRUITFUL), and AtTSF (TWIN SISTER OF FT). Our findings show that ClWRKY48 enhances phosphate absorption and slows the transition from the vegetative to the reproductive stage in ClWRKY48 transgenic Arabidopsis.

The effects of temperature, salt, and phosphate on biofilm and exopolysaccharide production by Azotobacter spp.

Inoculation of agriculturally important biofilms to plants under stress conditions has been of great interest in recent years. Therefore, in this study, biofilm- and exopolysaccharide (EPS)-forming ability of Azotobacter spp. was examined under different temperatures, NaCl concentrations, and phosphate levels. Azotobacter strains formed varying levels of biofilm and EPS depending on the tested factors. The pattern of biofilm formation was similar to that of EPS production under the conditions tested. Biofilm and EPS production at 28°C was consistently higher than at either 18 or 37°C. Biofilm production significantly increased in A. chroococcum strains (SBS2, SBS4, and SBS12) and A. vinelandii SBS6 with increasing salinity. Furthermore, a strong negative correlation was observed between biofilm or EPS production and increasing phosphate concentrations. Higher phosphate concentrations decreased biofilm and EPS production. In conclusion, contrary to temperature and phosphate effect, salinity differently affected biofilm and EPS production by Azotobacter strains.

Kinetic studies on arsenic release from geogenically enriched soils under oxidized and reduced conditions

Arsenic (As) release under natural conditions controls As mobility, bioavailability, and toxicity in soils. However, batch kinetic investigations on As release are often done using As-spiked soils at wide soil to water ratios of 1: 10 to 1:50, which are far from the typical field conditions. In the present work, the kinetics of As release was studied in five naturally enriched soils under two moisture or redox regimes of oxidized (50 % of saturation moisture) and reduced (saturation moisture) using phosphate as an extractant over 60 days. The rate of As release was fast initially and then gradually decreased until the end of reaction time in all soils under both redox conditions, beyond 60 days in most soils. The cumulative amount of As released from soils under oxidized conditions ranged from 3.2 to 60.1 mg/kg. However, only a small fraction of total As (3.3 to 8.5 %) was released. Arsenic release increased significantly in soils with increasing phosphate concentration. Arsenic release under reduced conditions was much higher than under oxidized conditions, ranging from 8.0 to 21 % of total As. Among six kinetic models, the power function model best described As release from all soils under both redox conditions and under low or high concentration of extracting solution. Our results imply that extensive use of phosphate fertilizers in these soils would increase the release of As and augment its environmental cycling. The higher As release under reduced conditions also suggests that environmental risks of these soils will significantly increase if they are utilized under near-saturation conditions or if they are poorly drained.

Phosphate Limitation Susceptibility in Saccharomyces Cerevisiae

Phosphate is a protein vital for all organismal bodies and is a resource bacteria compete for. Bakers yeast activity under several concentrations of phosphate and an alkaline solution was observed through absorbance spectroscopy as a means of measuring the various levels of inhibition from several varying concentrations. This was expected to show increased bacterial activity to increased phosphate concentration. Under higher concentrations of phosphate, Saccharomyces Cerevisiae became inhibited. This study focused on determining if the activity of the yeast changes based on the varying concentrations of phosphate solutions.

Comparison of metabolic effects of mitochondrial dysfunctions in the context of vulnerability to fatigue: computer simulation study

In recent years, the accumulation of phosphate ions and the increase in acidity have been described as crucial metabolic fatigue-leading factors that disturb muscle fiber contractions. This fact is especially important in the context of mitochondrial dysfunctions in which excessive fatigue is one of the possible symptoms. However, little is known about the precise fatigue-inducing thresholds of work intensity in mitochondrial dysfunctions of various types and at various stages of their severity. Possible interactions of additional factors such as disturbances in electrolyte concentrations (i.e. magnesium ions) were also not precisely defined. One of the best-suited tools for this kind of problem is systems biology, which enables modeling of metabolic pathways. In this research, a computer model of working skeletal muscle was adapted. The relationship between the decrease in oxidative phosphorylation and the workload shows a linear dependence for dysfunctions that evenly disturb the activity of each element of the pathway (which is equivalent to the decrease in mitochondrial mass). In case of dysfunctions that disrupt only one element of the pathway, the relationship between fatigue threshold and exercise intensity is exponential, but with higher threshold deficiency values. Muscle phosphate levels were the most vulnerable to disruptions of complex III and ATP synthase. Surprisingly, disruptions of the ATP/ADP exchanger emerged as equally disruptive and capable of significantly increasing phosphate concentrations also in the rest state, whereas the impact of the impairment of the phosphate transporter was negligible. Perturbations in magnesium concentration also did not show a significant effect in any of these models.

Causes of the extensive hypoxia in the Gulf of Riga in 2018

Abstract. The Gulf of Riga is a relatively shallow bay connected to the deeper central Baltic Sea (Baltic Proper) via straits with sills. The decrease in the near-bottom oxygen levels from spring to autumn is a common feature in the gulf, but in 2018, extensive hypoxia was observed. We analyzed temperature, salinity, oxygen, and nutrient data collected in 2018, along with historical data available from environmental databases. Meteorological and hydrological data from the study year were compared with their long-term means and variability. We suggest that pronounced oxygen depletion occurred in 2018 due to a distinct development of vertical stratification. Seasonal stratification developed early and was stronger in spring–summer 2018 than on average due to high heat flux and weak winds. Dominating northeasterly winds in early spring and summer supported the inflow of saltier waters from the Baltic Proper that created an additional deep pycnocline restricting vertical transport between the near-bottom layer (NBL) and the water column above. The estimated oxygen consumption rate in the NBL in spring–summer 2018 was about 1.7 mmolO2m-2h-1, which exceeded the oxygen input to the NBL due to advection and vertical mixing. Such a consumption rate leads to near-bottom hypoxia in all years when vertical mixing in autumn reaches the seabed later than on average according to the long-term (1979–2018) meteorological conditions. The observed increase in phosphate concentrations in the NBL in summer 2018 suggests a significant sediment phosphorus release in hypoxic conditions counteracting the mitigation measures to combat eutrophication. Since climate change projections predict that meteorological conditions comparable to those in 2018 will occur more frequently, extensive hypoxia would be more common in the Gulf of Riga and other coastal basins with similar morphology and human-induced elevated input of nutrients.

Effects of terrestrial dissolved organic matter on a bloom of the toxic cyanobacteria, Raphidiopsis raciborskii

The concentration of coloured terrestrial dissolved organic matter (tDOM) from vegetation appears to be increasing in lakes in some regions of the world, leading to the term brownification. The light attenuating effect of coloured tDOM on phytoplankton growth has been a major focus of attention, but the phytotoxic effects of tDOM, particularly on cyanobacterial blooms, are less well understood. This mesocosm study tested whether coloured tDOM, leached from the leaves of a Eucalyptus tree species, inhibited a naturally occurring bloom of the toxic cyanobacterium, Raphidiopsis raciborskii, in a reservoir over a 10 day period. The study found that tDOM leachate, measured as dissolved organic carbon (DOC), inhibited photosynthesis and growth of both R. raciborskii, as well as species present at lower densities, i.e. other cyanobacteria and diatoms. However, the effect was greater at higher tDOM input loads. The photosynthetic yield (Fv/Fm) of cyanobacteria decreased rapidly in treatments with 5.9 and 25 mg L−1 DOC addition, compared to the control (reservoir water with background DOC concentration of 6.85 ± 1.09 mg L−1). tDOM had no measurable effect in the 2 and 3.3 mg L−1 DOC addition treatments. By day 5, cell densities of cyanobacteria, including R. raciborskii, and diatoms, in treatments with 5.9 and 25 mg L−1 DOC addition were significantly lower than the control with no tDOM addition, and this effect continued throughout the experiment. This is despite the leachate addition increasing phosphate concentrations which counteracted the low background concentrations of phosphate. Light attenuation and dissolved oxygen (DO) levels were also affected by the tDOM addition, but were only significantly lower in the 25 mg L−1 DOC treatment compared with the control. DOC, dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) concentrations all decreased in the tDOM addition treatments over the first 3 days, as the microbial cell densities increased. The components of the tDOM that decreased over time were determined by 1H NMR spectroscopy in the 25 mg L−1 DOC treatment. After 5 d, the relative concentrations of fatty acids, sugars and gallic acid decreased by around 60%, while concentrations of flavonoids and myo-inositol decreased by 45 and 35% respectively. This study suggests that phytotoxic compounds in tDOM can suppress cyanobacterial blooms, despite the increased nutrient inputs. This has implications for predicting the future likelihood of cyanobacterial blooms in lakes and reservoirs with climate-change driven changes in flow events, and other changes in the amount and types of vegetation cover. Revegetation of riparian zones, resulting in increased tDOM into waterways, may also be beneficial in reducing cyanobacterial blooms.

Mg-Al Layered Double Hydroxide Doped Activated Carbon Composites for Phosphate Removal from Synthetic Water: Adsorption and Thermodynamics Studies

Increased phosphate concentration in water bodies has led to eutrophication, and its removal is an inevitable requirement of sustainable wastewater purification systems. In this study, MgAl layered doubled hydroxide (LDH) composites doped on the surface of activated carbon (AC/MgAl LDH) with various (Mg + Al) total metal loading (5 wt%, 10 wt%, and 15 wt%) were prepared by the co-precipitation method. The influence of (Mg + Al) total metal loading onto AC was examined to remove phosphate ions from aqueous solutions. The effect of adsorption parameters, including adsorbent dosage, initial solution pH, initial phosphate concentration, contact time, and experiment temperature, were investigated via batch adsorption experiments. The adsorption results demonstrated that the phosphate adsorption capacity significantly improved with increasing the (Mg + Al) metal loading on the surface of AC. The maximum Langmuir phosphate adsorption capacity was 337.2 mg phosphate per gram of AC/MgAl-3 LDH composite (15 wt% Mg + Al) composite at pH ~6.3, 22 °C, and 1 g/L of adsorbent. The kinetic data were best fitted with the pseudo-second order model. The initial solution pH notably influenced the phosphate removal by AC/MgAl-3 LDH composite with a maximum removal at pH 2.3. According to the spent adsorbent characterization results, the dominant mechanisms of phosphate removal by AC/MgAl-3 LDH were electrostatic interactions, ion exchange, and inner-sphere complexation. The phosphate adsorption capacity was gradually increased with increasing the experiment temperature, suggesting an endothermic adsorption process. Overall, the AC/MgAl LDH composites pave the way for an effective strategy for phosphate removal from aqueous solutions.