Decrease In Phosphate Concentration Research Articles

Laju Reaksi Penghilangan Fosfat pada Limbah Cair Artifisial NPK Menggunakan Sistem Floating Treatment Wetlands

Floating Treatment Wetland (FTW) is a form of wetland that functions to remove waste such as Nitrogen (N element) and Phosphorus (Phosphorous/P element) waste by utilizing plant roots as pollutant absorbers. This study aims to examine the reaction rate of phosphate removal from synthetic P waste through FTW. The water plants used were water jasmine (Echinodorus palifolius) and banana (Helliconia psittaforum). Four FTW ponds are filled with synthetic P waste. The first pond is a control pond, while the second pond is filled with FTW without plants, and the third and fourth ponds are filled with each of the aquatic plants mentioned above. The study was conducted from July to mid-August 2019. Water samples were taken in four pools five times in the first week, three times in the second week and twice in the third to sixth weeks. The parameters measured are water temperature, pH, Oxidative Reductive Potential (ORP) and phosphate. The data analysis carried out was calculating the phosphate reaction rate for each measured sample. The rate of phosphate decreases in proportion to the decrease in phosphate concentration in the test pond. Aquatic plants have been proven to remove phosphate from synthetic waste by using it as a nutrient for plant growth.

Variation in the fibroblast growth factor 23 (FGF23) gene associates with serum FGF23 and bone strength in infants.

Introduction: The effects of genetic variation in fibroblast growth factor 23 (FGF23) are unclear. This study explores the associations of single-nucleotide polymorphisms (SNPs) of FGF23 with phosphate and vitamin D metabolism and bone strength in early childhood. Methods: The study is part of the vitamin D intervention in infant (VIDI) trial (2013-2016), in which healthy term infants born to mothers of Northern European origin received vitamin D3 supplementation of 10 or 30μg/day from 2 weeks to 24months of age (ClinicalTrials.gov NCT01723852). Intact and C-terminal FGF23 (cFGF23), 25-hydroxyvitamin D (25-OHD), parathyroid hormone, phosphate, and peripheral quantitative computed tomography (pQCT)-derived bone strength parameters were analyzed at 12 and 24months. The study included 622 VIDI participants with genotyping data on FGF23 SNPs rs7955866, rs11063112, and rs13312770. Results: Rs7955866 minor allele homozygotes had lowest cFGF23at both time-points (mixed model for repeated measurements, pvariant = 0.009). Minor alleles of rs11063112 were associated with a greater age-related decrease in phosphate concentration (pinteraction = 0.038) from 12 to 24months. Heterozygotes of rs13312770 had the greatest total bone mineral content (total BMC), cross-sectional area (total CSA), and polar moment of inertia (PMI) at 24months (ANOVA p = 0.005, 0.037, and 0.036, respectively). Rs13312770 minor alleles were associated with a greater increase of total BMC, but a smaller increase of total CSA and PMI, during follow-up (pinteraction <0.001, 0.043, and 0.012, respectively). Genotype of FGF23 did not modify 25-OHD. Conclusion: The study finds that genetic variation in FGF23 modifies cFGF23, phosphate, and pQCT-derived bone strength parameters from 12 to 24months of age. These findings potentially promote an understanding of the regulation of FGF23 and its role in bone metabolism and temporal changes thereof during early childhood.

Prokaryotic Diversity and Dynamics during Dinoflagellate Bloom Decays in Coastal Tunisian Waters

(1) Background: Harmful algal blooms (HABs) can negatively impact marine ecosystems, but few studies have evaluated the microbial diversity associated with HABs and its potential role in the fates of these proliferations. (2) Methods: Marine prokaryotic diversity was investigated using high-throughput sequencing of the 16S rRNA gene during the bloom declines of two dinoflagellates detected in the summer of 2019 along the northern and southern Tunisian coasts (South Mediterranean Sea). The species Gymnodinium impudicum (Carthage, Tunis Gulf) and Alexandrium minutum (Sfax, Gabes Gulf) were identified using microscopy and molecular methods and were related to physicochemical factors and prokaryotic compositions. (3) Results: The abundance of G. impudicum decreased over time with decreasing phosphate concentrations. During the G. impudicum bloom decay, prokaryotes were predominated by the archaeal MGII group (Thalassarchaeaceae), Pelagibacterales (SAR11), Rhodobacterales, and Flavobacteriales. At Sfax, the abundance of A. minutum declined with decreasing phosphate concentrations and increasing pH. At the A. minutum peak, prokaryotic communities were largely dominated by anoxygenic phototrophic sulfur-oxidizing Chromatiaceae (Gammaproteobacteria) before decreasing at the end of the survey. Both the ubiquitous archaeal MGII group and Pelagibacterales were found in low proportions during the A. minutum decay. Contrary to the photosynthetic Cyanobacteria, the photo-autotrophic and -heterotrophic Rhodobacterales and Flavobacteriales contents remained stable during the dinoflagellate bloom decays. (4) Conclusions: These results indicated changes in prokaryotic community diversity during dinoflagellate bloom decays, suggesting different bacterial adaptations to environmental conditions, with stable core populations that were potentially able to degrade HABs.

Gas–Liquid Reactions to Synthesize Positively Charged Fe3O4 Nanoparticles on Polyurethane Sponge for Stable and Recyclable Adsorbents for the Removal of Phosphate from Water

The application of most current phosphate adsorbents is limited by their high cost, low removal capacity, difficulty of recovery, and short lifetime. In this study, we developed a gas–liquid reaction assisted by a coordination method to prepare highly positively charged ferroferric oxide (Fe3O4) nanoparticles loaded on polyurethane sponge. It was found that the gas–liquid reaction drastically decreases the size and increases the loading capacity of Fe3O4 nanoparticles as compared with the conventional liquid method. Further, the use of trimethylamine vapor induced the coordination of Fe3+, facilitated the formation of free Cl ions, and inhibited the hydrolysis of Fe–Cl bonds, thus greatly decreasing the amount of hydroxyl groups and increasing the surface positive charge on Fe3O4 nanoparticles. As a result, the Fe3O4 nanoparticles in this study have a saturated PO43– adsorption capacity of 229.8 mg·g–1, which was appreciably higher than that of conventional Fe3O4 adsorbents (57.8 mg·g–1). Our study further revealed that the introduction of a thin layer of polyurethane coating on the surface of Fe3O4 nanoparticle-composited adsorbents could drastically improve their stability while preserving the adsorption capacity under the impact of water (500 rpm stirring for 72 h). The composited adsorbents also preserve the adsorption capacity after recycling three times. Finally, the adsorption experiment on real river wastewater indicated that the composited adsorbents enable the decrease of phosphate concentration from 0.6 to 0.02 ppm, reflecting the application potential for relieving phosphate pollution in neutral waters.

Early hypophosphatemia in critically ill children and the effect of parenteral nutrition: A secondary analysis of the PEPaNIC RCT

Hypophosphatemia during critical illness has been associated with adverse outcome. The reintroduction of enteral or parenteral nutrition, leading to refeeding hypophosphatemia (RFH), has been presented as potential risk factor. We investigated the occurrence of early RFH, its association with clinical outcome, and the impact of early parenteral nutrition (PN) on the development of early RFH in pediatric critical illness. This is a secondary analysis of the PEPaNIC randomized controlled trial (N=1440), which showed that withholding supplemental parenteral nutrition (PN) for 1 week (late-PN) in the pediatric intensive care unit (PICU) accelerated recovery and reduced new infections compared to early-PN (<24h). Patients with renal replacement therapy or unavailable phosphate concentrations were excluded from this analysis. Early RFH was defined as serum/plasma phosphate <0.65mmol/L and a drop of >0.16mmol/L within 3 days of admission to the PICU. The association between baseline characteristics and early RFH, and the association of early RFH with clinical outcome were investigated using logistic and linear regression models, both uncorrected and corrected for possible confounders. To examine the impact of nutritional intake on phosphate concentrations, structural nested mean models with propensity score and censoring models were used. A total of 1247 patients were eligible (618 early-PN, 629 late-PN). Early RFH occurred in 40 patients (3%) in total, significantly more in the early-PN group (n=31, within-group occurrence 5%) than in the late-PN-group (n=9, within-group occurrence 1%, p<0.001). Patients who were older (OR 1.14 (95% CI 1.08; 1.21) per year added, p<0.001) and who had a higher Pediatric Risk of Mortality (PIM3) score had a higher risk of developing early RFH (OR 1.36 (95% CI 1.15; 1.59) per unit added, p<0.001), whereas patients in the late-PN group had a lower risk of early RFH (OR 0.24 (95% CI 0.10; 0.49), p<0.001). Early RFH was significantly associated with a 56% longer PICU stay (p=0.003) and 42% longer hospital stay (p=0.007), but not with new infections (OR 2.01 (95% CI 0.90; 4.30), p=0.08) or length of mechanical ventilatory support (OR 1.05 (95% CI-3.92; 6.03), p=0.68), when adjusted for possible confounders. Increase of parenteral nutrition intake (in % kcal of predicted resting energy expenditure) decreased phosphate concentrations (c=-0.002 (95% CI -0.002;-0.001). Early RFH occurred in 3% of critically ill children. Patients randomized to late-PN had a lower chance of developing early RFH, which may be explained by the more gradual build-up of nutrition. As early RFH might impact recovery, it is important to closely monitor phosphate concentrations in patients, especially of those at risk for early RFH.

Phosphate induced surface transformation alleviated the cytotoxicity of Y2O3 nanoparticles to tobacco BY-2 cells

The wide applications of rare earth oxide nanoparticles (REO NPs) in various fields and their subsequent release into the environment have attracted the research of their effects on organisms. In this study, the toxicity of yttrium oxide (Y2O3) NPs to tobacco BY-2 cells was evaluated and the importance of phosphate in the medium on the toxicity of Y2O3 NPs was revealed. 50 mg L−1 Y2O3 NPs induced 52.4% cellular growth inhibition after 24-h exposure. Phosphate inhibited the release of Y3+ from Y2O3 NPs from 6.00 to 0.04 mg L−1 at 24 h, thus reduced the toxicity of Y2O3 NPs. The surface charge of Y2O3 NPs changed from 24.0 mV (in deionized water) to −7.6 mV (in phosphate solution), which induced the aggregation of Y2O3 NPs. The change of surface properties reduced the direct nanotoxicity of Y2O3 NPs. High-resolution transmission electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and X-ray diffraction results demonstrated that phosphate transformed the surface of Y2O3 NPs to amorphous YPO4. This surface transformation decreased phosphate concentration in the medium. The dialysis membrane encapsulation experiment further identified the contribution percentage of direct nanotoxicity and indirect toxicity (i.e., phosphate depletion) of Y2O3 NPs to tobacco BY-2 cells in the presence of phosphate to be 68.3% and 31.7%, respectively. This study highlights the significant role of phosphate in altering the environmental behavior and toxicity of REO NPs.

Variable C∕P composition of organic production and its effect on ocean carbon storage in glacial-like model simulations

Abstract. During the four most recent glacial maxima, atmospheric CO2 has been lowered by about 90–100 ppm with respect to interglacial concentrations. It is likely that most of the atmospheric CO2 deficit was stored in the ocean. Changes in the biological pump, which are related to the efficiency of the biological carbon uptake in the surface ocean and/or of the export of organic carbon to the deep ocean, have been proposed as a key mechanism for the increased glacial oceanic CO2 storage. The biological pump is strongly constrained by the amount of available surface nutrients. In models, it is generally assumed that the ratio between elemental nutrients, such as phosphorus, and carbon (C∕P ratio) in organic material is fixed according to the classical Redfield ratio. The constant Redfield ratio appears to approximately hold when averaged over basin scales, but observations document highly variable C∕P ratios on regional scales and between species. If the C∕P ratio increases when phosphate availability is scarce, as observations suggest, this has the potential to further increase glacial oceanic CO2 storage in response to changes in surface nutrient distributions. In the present study, we perform a sensitivity study to test how a phosphate-concentration-dependent C∕P ratio influences the oceanic CO2 storage in an Earth system model of intermediate complexity (cGENIE). We carry out simulations of glacial-like changes in albedo, radiative forcing, wind-forced circulation, remineralization depth of organic matter, and mineral dust deposition. Specifically, we compare model versions with the classical constant Redfield ratio and an observationally motivated variable C∕P ratio, in which the carbon uptake increases with decreasing phosphate concentration. While a flexible C∕P ratio does not impact the model's ability to simulate benthic δ13C patterns seen in observational data, our results indicate that, in production of organic matter, flexible C∕P can further increase the oceanic storage of CO2 in glacial model simulations. Past and future changes in the C∕P ratio thus have implications for correctly projecting changes in oceanic carbon storage in glacial-to-interglacial transitions as well as in the present context of increasing atmospheric CO2 concentrations.

Removal and biomineralization of Pb2+ in water by fungus Phanerochaete chrysoporium

The removal and biomineralization of Pb2+ (200 mg/L) in water were investigated utilizing mature mycelia of Phanerochaete chrysoporium. Mycelial dosage, initial Pb2+ concentration, solution pH and treatment time all were shown to have an influence on Pb2+ removal. Granular, lead-containing precipitation was formed on the fungal hyphae upon exposure to lead nitrate, which was confirmed from scanning electron micrograph/Energy Dispersive Spectrometer (SEM/EDS). Energy dispersive X-ray spectroscopic analysis revealed the presence of lead (48.5% by weight) along with phosphorus in the precipitate. This extracellular precipitate was further identified as pyromorphite lead hydroxyphosphate [Pb5(PO4)3OH] by X-ray powder diffraction (XRD) analysis. During Pb2+ removal, size-enlarged mineral precipitation, and clustered nanospherical particles formed on the hyphae were revealed by SEM/XRD. A remarkable increase of mycelial phosphatase activity of 1.5 times that of the control and decreased phosphate concentration in solution (16.76 mg/L to 1.39 mg/L) initially upon exposure to Pb2+ suggested that phosphatase may hydrolyze organic phosphorus into inorganic phosphate and release it into solution, participating in the biomineralization of Pb2+. Toxicity tests showed that the toxicity of Pb2+ polluted water decreased after treatment. The results clearly demonstrate previously unknown lead biomineralization as pyromorphite through fungal phosphatase.

Utilization of Aquatic Plants as Phytoremediation Agents of Tofu Liquid Waste

The tofu industry produces a lot of tofu liquid waste and has the potential to cause waters to be toxic and dangerous for the life of the biota aquatic. This research uses a phytoremediation method using floating water plants. The purpose of this research was to obtain water plants that have better absorption ability as phytoremediation agents for tofu liquid waste between Lemna and Kiapu aquatic plants. This research was conducted at the Laboratory of Aquatic Resources, Faculty of Fisheries and Marine Sciences, Padjadjaran University from March to September 2019. The method used in this research was an experimental method with a Completely Randomized Design (CRD) consisting of three treatments and five replications. Tofu liquid waste samples were obtained from the Tofu Factory in the Cibuntu Tofu Industry Center. Physical and chemical parameters observed include temperature, acidity, dissolved oxygen, BOD5, nitrate, and phosphate. The results showed that the Kiapu had better nitrate and phosphate absorption ability than Lemna and the combination treatments for 15 days of observation. The result showed that the decrease in nitrate concentration was 10.12-62.24% and the decrease in phosphate concentration was 6.67-54.23%. Kiapu can be recommended as phytoremediation agents for tofu liquid waste to remediate high organic matter before being discharged directly into water bodies.

Lake water phosphate reduction with advanced wastewater treatment in watershed, at Lake Hamana, Shizuoka Prefecture, Japan, from 1995 to 2016.

Lake Hamana is a semi-enclosed brackish lake amid agricultural and residential land. Monthly vertical profiles of nutrients, total phosphorus (TP), and total nitrogen (TN) at twelve sampling stations in the lake were obtained from 1995 to 2016. Freshwater samples were also obtained from five stations in the river flowing into the lake. Significant decreases were seen in phosphate, TP, and TN concentrations at most lake and all river stations. Decrease in phosphate concentration reflects reduced organic matter and nutrient load into the lake due to increased sewage coverage. Nitrate concentration significantly increased at four stations, whereas ammonium and TN concentrations significantly decreased. This could be due to inefficient nitrification/denitrification of wastewater. At all stations, the nitrogen to phosphate ratio in surface water was higher than 16 and increased significantly. Therefore, phosphate limitation could be strengthened by the decrease in phosphate and increase in nitrate concentrations in the lake.

Effect of phosphate variation on morphology and electrocatalytic activity (OER) of hydrous nickel pyrophosphate thin films

Simple, cost effective chemical bath deposition (CBD) method is used for synthesis of hydrous nickel pyrophosphate (Ni2P2O7·8H2O) thin films as an electrocatalyst on stainless steel (SS) substrate for OER application. The effect of phosphate variation is studied via preparing thin films with different nickel and phosphate molar weight ratio, as decreasing phosphate concentration in the reaction bath willow leaf like morphology changes to compact microflower with rectangular petals. As-prepared Ni2P2O7·8H2O at a molar weight ratio of 1:2 (nickel: phosphate) gives better results as an electrocatalyst with low overpotential of 308 mV at 25 mA cm−2 current density, as compare to other molar weight ratios (1:1 and 1:0.5). This excellent electrocatalytic performance of hydrous nickel pyrophosphate thin film electrodes is credited to high ECSA and low impedance of electrocatalyst. Also, it exhibits good stability over 9 h in 1 M KOH at constant potential.

A comprehensive laboratory assessment of the effects of sewer-dosed iron salts on wastewater treatment processes

The effect of iron-dosing in the sewer system, on wastewater treatment processes, was investigated using laboratory-scale wastewater systems comprising sewers, wastewater treatment reactors, sludge thickeners, and anaerobic sludge digesters. Two systems, fed with real domestic wastewater, were operated for over a year. The experimental system received ferric chloride (FeCl3) dosing at 10 mgFe L−1 in the sewer reactor whereas the control system received none. Wastewater, sludge and biogas were extensively sampled, and analysed for relevant parameters. The FeCl3-dosed experimental system displayed a decreased sulfide concentration (by 4.3 ± 0.5 mgS L−1) in sewer effluent, decreased phosphate concentration (by 4.7 ± 0.5 mgP L−1) in biological treatment reactor effluent, and decreased hydrogen sulfide concentration in biogas (911.5 ± 189.9 ppm to 130.0 ± 5.9 ppm), as compared with the control system. The biological nitrogen removal performance of the treatment reactor, and biogas production in the anaerobic digester were not affected by FeCl3-dosing. Furthermore, the dewaterability of the anaerobically digested sludge was enhanced by 17.7 ± 1.0%. These findings demonstrate that iron-dosing to sewers can achieve multiple benefits including sulfide removal in sewers, phosphorus removal during wastewater treatment, and hydrogen sulfide (H2S) removal during biogas generation. Therefore, an integrated approach should be taken when considering iron salts usage in an urban wastewater system.

Effects of human-driven water stress on river ecosystems: a meta-analysis

Human appropriation of water resources may induce water stress in freshwater ecosystems when ecosystem needs are not met. Intensive abstraction and regulation cause river ecosystems to shift towards non-natural flow regimes, which might have implications for their water quality, biological structure and functioning. We performed a meta-analysis of published studies to assess the potential effects of water stress on nutrients, microcontaminants, biological communities (bacteria, algae, invertebrates and fish), and ecosystem functions (organic matter breakdown, gross primary production and respiration). Despite the different nature of the flow regime changes, our meta-analysis showed significant effects of human-driven water stress, such as significant increases in algal biomass and metabolism and reduced invertebrate richness, abundance and density and organic matter decomposition. Water stress also significantly decreased phosphate concentration and increased the concentration of pharmaceutical compounds. The magnitude of significant effects was dependent on climate, rainfall regime, period of the year, river size and type of water stress. Among the different causes of water stress, flow regulation by dams produced the strongest effects, followed by water abstraction and channelization.

High-throughput optimization of the chemically defined synthetic medium for the production of erythromycin A.

Erythromycin A is an important antibiotic. A chemically defined synthetic medium for erythromycin production was systematically optimized in this study. A high-throughput method was employed to reduce the number of components and optimize the concentration of each component. After two round single composition deletion experiment, only 19 components were remained in the medium, and then the concentration of each component was optimized through PB experiment. The optimal medium from the PB experiment was further optimized according to the nitrogen and phosphate metabolic consumption in 5L bioreactor. It was observed that among the 8 amino acids concluded in the media, 4 amino acids were first consumed, when they are almost depleted, the other 4 amino acids were initiated their consumption afterwards in 5L bioreactor. The decrease of phosphate concentration would increase qglc and qery. However, when phosphate concentration was too low, the production of erythromycin was hindered. The positive correlation between intracellular metabolite pools and Yery/glc indicated that low phosphate concentration in the medium can promote cell metabolism especially secondary metabolism during the stationary phase; however, if it was too low (5mmol/L), the cell metabolism and secondary metabolism would both slow down. The erythromycin titer in the optimized medium (medium V) reached 1380mg/L, which was 17 times higher than the previously used synthetic medium in our lab. The optimized medium can facilitate the metabolomics study or metabolic flux analysis of the erythromycin fermentation process, which laid a solid foundation for further study of erythromycin fermentation process.

The interrelation between FGF23 and glucose metabolism in humans

AimsDifferent studies point to a link between glucose metabolism and Fibroblast Growth Factor 23 (FGF23), an osteocyte-derived phosphaturic hormone. We aimed to investigate in humans the effect of (I) a glucose load and (II) a hyperinsulinemic-euglycemic clamp on FGF23 concentrations and conversely (III) the effect of a diet-induced increase in FGF23 concentration on glucose and insulin concentrations. MethodsPlasma cFGF23 concentrations were measured during: I. an oral glucose tolerance test in eight adults with impaired glucose tolerance and vitamin D deficiency and II. a hyperinsulinemic-euglycemic clamp in nine healthy adults. III. Serum glucose and insulin concentrations were measured in nine healthy adults receiving a single-day phosphate-enriched or -restricted diet. ResultsI. A glucose load decreased FGF23 and phosphate concentrations. II. The hyperinsulinemic-euglycemic clamp decreased phosphate concentrations, but did not affect FGF23 concentrations. III. Fasting insulin and glucose concentrations remained unchanged after a diet-induced increase in FGF23 concentration. ConclusionsAn oral glucose load in vitamin D deficient patients with impaired glucose metabolism decreased FGF23 concentrations, which cannot be attributed to changes in insulin concentration. Thus, bone may react rapidly after glucose loading by alternating FGF23 secretion. A diet-induced increase in FGF23 concentrations did not affect fasting glucose or insulin levels.

The Importance of Mesodinium rubrum at Post-Spring Bloom Nutrient and Phytoplankton Dynamics in the Vertically Stratified Baltic Sea

The inter-annual dynamics of the photosynthetic ciliate Mesodinium rubrum in the central Gulf of Finland in spring-summer continuum during five years were followed. The analysis was mainly based on high-resolution measurements and sampling in the surface layer along the ferry route Tallinn-Helsinki. The main purpose was to analyze the dynamics of M. rubrum biomass, its contribution to the photosynthetic plankton biomass, and the influence of water temperature and variations of inorganic nutrients in the surface and sub-surface layer on its dynamics. The analysis revealed that the outcome of the M. rubrum bloom in spring was largely related to the surface layer water temperature – in the years of earlier warming, the higher biomass of this species was formed. The photosynthetic ciliate was an important primary producer in all studied years during the late phase or post-spring bloom period in the Gulf of Finland. The maximum proportion of M. rubrum in the photosynthetic plankton community was estimated up to 88% in May and up to 91% in June. We relate the observed post-spring bloom decrease of phosphate concentrations in the surface layer to the dominance and growth of M. rubrum. We suggest that this link can be explained by the vertical migration behaviour of M. rubrum and phosphate utilization in the surface layer coupled with inorganic nitrogen assimilation in the sub-surface layer. Thus, the dynamics of M. rubrum could strongly influence the amount of post-spring bloom excess PO43- in the euphotic layer and the depth of nitracline in the Gulf of Finland.

Ammonia removal from poultry manure leachate via struvite precipitation: a strategy for more efficient anaerobic digestion

To improve poultry waste management, the feasibility of enabling efficient anaerobic digestion of poultry manure through reduction of ammonia accumulation is examined. This study employs struvite precipitation to control ammonia accumulation, and focuses on the efficacy of ammonia removal under neutral reaction conditions (pH = 7). The impacts of phosphate and magnesium additives, pH, temperature and the N:Mg:P molar ratio are quantified. Magnesium chloride (MgCl2 • 6H2O) and monopotassium phosphate (KH2PO4) are shown to be the most efficient combination of additives for total ammoniacal nitrogen (TAN) reduction of poultry manure leachate under neutral reaction conditions (pH = 7), demonstrating a TAN reduction of 90.3%. Modification of molar ratios (NH4:Mg:PO4) evidenced no significant benefit with regard to TAN reduction. However, increasing the fraction of supplementary magnesium resulted in a statistically significant (p < 0.05) decrease in phosphate concentration within the leachate. This study demonstrates the advantages of struvite precipitation, as a method of ammonia control, to improve anaerobic digestion and hence management of poultry manure. Although an effective means of TAN control, struvite precipitation from poultry manure is an ineffective means of obtaining pure struvite due to the formation of co-precipitates.

Long‐term decrease in phosphate concentrations in the surface layer of the southern Japan Sea

AbstractTo identify possible causes for the long‐term trends in nutrient concentrations in the southern Japan Sea (JS), we studied nutrient concentrations that were obtained by the Japan Meteorological Agency. Our evaluation shows that phosphate concentrations declined in the surface layers in summer (0–20 and 21–50 m depth) and winter (0–20, 21–50, and 51–100 m depth) over the last 40 years, while no significant linear trend was observed for nitrate concentrations. The declining trend in the phosphate concentration was quantified as 1.8–3.3 nM yr−1. The increase in atmospheric nutrient deposition to the JS could not explain the decline in phosphate concentration. In addition, the mixed‐layer depth during winter did not demonstrate any significant trend, and an increase in phosphate concentrations was not observed in any layers; therefore, the decrease in nutrient supply from deep JS water was not considered a major possible cause for the decline in the phosphate concentration. In contrast, the phosphate concentration in the surface of the southern JS during winter showed a significant positive correlation with the concentration in the 21–50 m depth layer of the saline East China Sea (ECS) water in the preceding summer, and the surface water of the southern JS was almost entirely replaced by water originating from the ECS during May–October. Therefore, it is concluded that the declining trend in the phosphate concentrations in the southern JS is caused by horizontal advection of ECS water.

In vitro phosphate-binding ability of calcium-based agents is augmented by co-administration of activated charcoal

Calcium carbonate is widely used as a phosphate binder in patients on maintenance hemodialysis. An unwanted side effect of calcium carbonate is hypercalcemia and vascular calcification. Oral activated charcoal (AC) is a non-selective and highly effective adsorbent. We hypothesized that AC augments the phosphate binding capacity of calcium-based agents. We performed an in vitro study to test this hypothesis. Simulated gastric fluid and intestinal fluid were prepared with a phosphate concentration of 10 mmol/l. Different dosages of calcium chloride (0.083 g, 0.167 g, and 0.250 g), AC (0.15 g, 0.30 g, and 0.45 g) or a combination of both were added to either gastric or intestinal fluid for phosphate binding. After a reaction time of 2 hours, phosphate concentrations in the supernatant were measured, and absolute reduction and percent reduction of phosphate were calculated. The phosphate-binding abilities of calcium chloride, AC, and a combination of both were compared. In simulated intestinal fluid there was no significant difference in the percent reduction of phosphate concentrations among the different calcium chloride concentration groups (28.90 ± 2.04 vs. 33.33 ± 3.90 vs. 31.86 ± 5.23) and there was still no significant difference in phosphate concentrations among the different AC groups (3.33 ± 0.08 vs. 3.26 ± 0.01 vs. 3.36 ± 0.11). In simulated gastric fluid phosphate concentrations at each of the time points (before the reaction, 1 hour after calcium chloride was added, and 2 hours after AC was added) were not significantly different. In simulated intestinal fluid the percent decrease in phosphate concentration in the calcium chloride + AC group was significantly higher than that in the calcium chloride group (48.23 ± 5.55 vs. 30.72 ± 6.11). AC alone had no phosphate-binding ability in either gastric or intestinal fluid. The phosphate-binding ability of calcium chloride was improved by AC in intestinal fluid.

Phosphorus stress of microphytoplankton community in the western subtropical North Pacific

Phosphorus stress in microphytoplankton (diatoms, dinoflagellates, Trichodesmium spp.) and small-sized unicellular cyanobacteria was assayed using a single-cell assay [enzyme-labelled fluorescence (ELF)]. The fractions of ELF-labelled cells varied within and between taxonomic groups along the 141.5°E transect between 20.47°N and 31.6°N. High percentages of ELF-labelled dinoflagellates (66―89%) and Trichodesmium spp. (∼100%) were consistently observed at the surface over the study area. In contrast, the fractions of ELF-labelled diatoms increased in the surface layer from north to south (10―83%), along with the decrease in phosphate concentrations (96 nM to 4 nM). Phosphate amendment experiments conducted in the phosphate-depleted southernmost station showed that phosphorus stress of diatoms and dinoflagellates was alleviated following phosphate addition. In contrast to the microphytoplankton communities, low percentages of ELF-labelled small-sized cyanobacteria were observed throughout the study area, suggesting that these cells were not P-limited. Our results revealed that dissolved organic phosphorus utilization could potentially be important for microphytoplankton in the western subtropical North Pacific.